release: 0.3.1

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/fpkg/app.go

@@ -4,12 +4,15 @@ import (
 	"encoding/json"
 	"log"
 	"os"
+	"path"
 
 	"git.gensokyo.uk/security/fortify/dbus"
+	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
-type bundleInfo struct {
+type appInfo struct {
 	Name    string `json:"name"`
 	Version string `json:"version"`
 
@@ -20,13 +23,15 @@ type bundleInfo struct {
 	// passed through to [fst.Config]
 	Groups []string `json:"groups,omitempty"`
 	// passed through to [fst.Config]
-	UserNS bool `json:"userns,omitempty"`
+	Devel bool `json:"devel,omitempty"`
+	// passed through to [fst.Config]
+	Userns bool `json:"userns,omitempty"`
 	// passed through to [fst.Config]
 	Net bool `json:"net,omitempty"`
 	// passed through to [fst.Config]
 	Dev bool `json:"dev,omitempty"`
 	// passed through to [fst.Config]
-	NoNewSession bool `json:"no_new_session,omitempty"`
+	Tty bool `json:"tty,omitempty"`
 	// passed through to [fst.Config]
 	MapRealUID bool `json:"map_real_uid,omitempty"`
 	// passed through to [fst.Config]
@@ -36,13 +41,11 @@ type bundleInfo struct {
 	// passed through to [fst.Config]
 	SessionBus *dbus.Config `json:"session_bus,omitempty"`
 	// passed through to [fst.Config]
-	Enablements system.Enablements `json:"enablements"`
+	Enablements system.Enablement `json:"enablements"`
 
-	// passed through inverted to [bwrap.SyscallPolicy]
-	Devel bool `json:"devel,omitempty"`
-	// passed through to [bwrap.SyscallPolicy]
+	// passed through to [fst.Config]
 	Multiarch bool `json:"multiarch,omitempty"`
-	// passed through to [bwrap.SyscallPolicy]
+	// passed through to [fst.Config]
 	Bluetooth bool `json:"bluetooth,omitempty"`
 
 	// allow gpu access within sandbox
@@ -59,8 +62,64 @@ type bundleInfo struct {
 	ActivationPackage string `json:"activation_package"`
 }
 
-func loadBundleInfo(name string, beforeFail func()) *bundleInfo {
-	bundle := new(bundleInfo)
+func (app *appInfo) toFst(pathSet *appPathSet, argv []string, flagDropShell bool) *fst.Config {
+	config := &fst.Config{
+		ID:   app.ID,
+		Path: argv[0],
+		Args: argv,
+		Confinement: fst.ConfinementConfig{
+			AppID:    app.AppID,
+			Groups:   app.Groups,
+			Username: "fortify",
+			Inner:    path.Join("/data/data", app.ID),
+			Outer:    pathSet.homeDir,
+			Sandbox: &fst.SandboxConfig{
+				Hostname:      formatHostname(app.Name),
+				Devel:         app.Devel,
+				Userns:        app.Userns,
+				Net:           app.Net,
+				Dev:           app.Dev,
+				Tty:           app.Tty || flagDropShell,
+				MapRealUID:    app.MapRealUID,
+				DirectWayland: app.DirectWayland,
+				Filesystem: []*fst.FilesystemConfig{
+					{Src: path.Join(pathSet.nixPath, "store"), Dst: "/nix/store", Must: true},
+					{Src: pathSet.metaPath, Dst: path.Join(fst.Tmp, "app"), Must: true},
+					{Src: "/etc/resolv.conf"},
+					{Src: "/sys/block"},
+					{Src: "/sys/bus"},
+					{Src: "/sys/class"},
+					{Src: "/sys/dev"},
+					{Src: "/sys/devices"},
+				},
+				Link: [][2]string{
+					{app.CurrentSystem, "/run/current-system"},
+					{"/run/current-system/sw/bin", "/bin"},
+					{"/run/current-system/sw/bin", "/usr/bin"},
+				},
+				Etc:     path.Join(pathSet.cacheDir, "etc"),
+				AutoEtc: true,
+			},
+			ExtraPerms: []*fst.ExtraPermConfig{
+				{Path: dataHome, Execute: true},
+				{Ensure: true, Path: pathSet.baseDir, Read: true, Write: true, Execute: true},
+			},
+			SystemBus:   app.SystemBus,
+			SessionBus:  app.SessionBus,
+			Enablements: app.Enablements,
+		},
+	}
+	if app.Multiarch {
+		config.Confinement.Sandbox.Seccomp |= seccomp.FlagMultiarch
+	}
+	if app.Bluetooth {
+		config.Confinement.Sandbox.Seccomp |= seccomp.FlagBluetooth
+	}
+	return config
+}
+
+func loadAppInfo(name string, beforeFail func()) *appInfo {
+	bundle := new(appInfo)
 	if f, err := os.Open(name); err != nil {
 		beforeFail()
 		log.Fatalf("cannot open bundle: %v", err)

cmd/fpkg/main.go

@@ -12,13 +12,11 @@ import (
 
 	"git.gensokyo.uk/security/fortify/command"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
 	"git.gensokyo.uk/security/fortify/internal"
-	init0 "git.gensokyo.uk/security/fortify/internal/app/init"
-	"git.gensokyo.uk/security/fortify/internal/app/shim"
+	"git.gensokyo.uk/security/fortify/internal/app"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
 )
 
 const shellPath = "/run/current-system/sw/bin/bash"
@@ -37,10 +35,10 @@ func init() {
 }
 
 func main() {
-	// early init argv0 check, skips root check and duplicate PR_SET_DUMPABLE
-	init0.TryArgv0()
+	// early init path, skips root check and duplicate PR_SET_DUMPABLE
+	sandbox.TryArgv0(fmsg.Output{}, fmsg.Prepare, internal.InstallFmsg)
 
-	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
+	if err := sandbox.SetDumpable(sandbox.SUID_DUMP_DISABLE); err != nil {
 		log.Printf("cannot set SUID_DUMP_DISABLE: %s", err)
 		// not fatal: this program runs as the privileged user
 	}
@@ -58,18 +56,13 @@ func main() {
 		flagDropShell bool
 	)
 	c := command.New(os.Stderr, log.Printf, "fpkg", func([]string) error {
-		fmsg.Store(flagVerbose)
-		if flagVerbose {
-			seccomp.CPrintln = log.Println
-		}
+		internal.InstallFmsg(flagVerbose)
 		return nil
 	}).
 		Flag(&flagVerbose, "v", command.BoolFlag(false), "Print debug messages to the console").
 		Flag(&flagDropShell, "s", command.BoolFlag(false), "Drop to a shell in place of next fortify action")
 
-	// internal commands
-	c.Command("shim", command.UsageInternal, func([]string) error { shim.Main(); return errSuccess })
-	c.Command("init", command.UsageInternal, func([]string) error { init0.Main(); return errSuccess })
+	c.Command("shim", command.UsageInternal, func([]string) error { app.ShimMain(); return errSuccess })
 
 	{
 		var (
@@ -126,10 +119,10 @@ func main() {
 				Parse bundle and app metadata, do pre-install checks.
 			*/
 
-			bundle := loadBundleInfo(path.Join(workDir, "bundle.json"), cleanup)
+			bundle := loadAppInfo(path.Join(workDir, "bundle.json"), cleanup)
 			pathSet := pathSetByApp(bundle.ID)
 
-			app := bundle
+			a := bundle
 			if s, err := os.Stat(pathSet.metaPath); err != nil {
 				if !os.IsNotExist(err) {
 					cleanup()
@@ -142,39 +135,39 @@ func main() {
 				log.Printf("metadata path %q is not a file", pathSet.metaPath)
 				return syscall.EBADMSG
 			} else {
-				app = loadBundleInfo(pathSet.metaPath, cleanup)
-				if app.ID != bundle.ID {
+				a = loadAppInfo(pathSet.metaPath, cleanup)
+				if a.ID != bundle.ID {
 					cleanup()
 					log.Printf("app %q claims to have identifier %q",
-						bundle.ID, app.ID)
+						bundle.ID, a.ID)
 					return syscall.EBADE
 				}
 				// sec: should verify credentials
 			}
 
-			if app != bundle {
+			if a != bundle {
 				// do not try to re-install
-				if app.NixGL == bundle.NixGL &&
-					app.CurrentSystem == bundle.CurrentSystem &&
-					app.Launcher == bundle.Launcher &&
-					app.ActivationPackage == bundle.ActivationPackage {
+				if a.NixGL == bundle.NixGL &&
+					a.CurrentSystem == bundle.CurrentSystem &&
+					a.Launcher == bundle.Launcher &&
+					a.ActivationPackage == bundle.ActivationPackage {
 					cleanup()
 					log.Printf("package %q is identical to local application %q",
-						pkgPath, app.ID)
+						pkgPath, a.ID)
 					return errSuccess
 				}
 
 				// AppID determines uid
-				if app.AppID != bundle.AppID {
+				if a.AppID != bundle.AppID {
 					cleanup()
 					log.Printf("package %q app id %d differs from installed %d",
-						pkgPath, bundle.AppID, app.AppID)
+						pkgPath, bundle.AppID, a.AppID)
 					return syscall.EBADE
 				}
 
 				// sec: should compare version string
 				fmsg.Verbosef("installing application %q version %q over local %q",
-					bundle.ID, bundle.Version, app.Version)
+					bundle.ID, bundle.Version, a.Version)
 			} else {
 				fmsg.Verbosef("application %q clean installation", bundle.ID)
 				// sec: should install credentials
@@ -275,9 +268,9 @@ func main() {
 
 			id := args[0]
 			pathSet := pathSetByApp(id)
-			app := loadBundleInfo(pathSet.metaPath, func() {})
-			if app.ID != id {
-				log.Printf("app %q claims to have identifier %q", id, app.ID)
+			a := loadAppInfo(pathSet.metaPath, func() {})
+			if a.ID != id {
+				log.Printf("app %q claims to have identifier %q", id, a.ID)
 				return syscall.EBADE
 			}
 
@@ -285,7 +278,7 @@ func main() {
 				Prepare nixGL.
 			*/
 
-			if app.GPU && flagAutoDrivers {
+			if a.GPU && flagAutoDrivers {
 				withNixDaemon(ctx, "nix-gl", []string{
 					"mkdir -p /nix/.nixGL/auto",
 					"rm -rf /nix/.nixGL/auto",
@@ -293,11 +286,11 @@ func main() {
 					"nix build --impure " +
 						"--out-link /nix/.nixGL/auto/opengl " +
 						"--override-input nixpkgs path:/etc/nixpkgs " +
-						"path:" + app.NixGL,
+						"path:" + a.NixGL,
 					"nix build --impure " +
 						"--out-link /nix/.nixGL/auto/vulkan " +
 						"--override-input nixpkgs path:/etc/nixpkgs " +
-						"path:" + app.NixGL + "#nixVulkanNvidia",
+						"path:" + a.NixGL + "#nixVulkanNvidia",
 				}, true, func(config *fst.Config) *fst.Config {
 					config.Confinement.Sandbox.Filesystem = append(config.Confinement.Sandbox.Filesystem, []*fst.FilesystemConfig{
 						{Src: "/etc/resolv.conf"},
@@ -309,7 +302,7 @@ func main() {
 					}...)
 					appendGPUFilesystem(config)
 					return config
-				}, app, pathSet, flagDropShellNixGL, func() {})
+				}, a, pathSet, flagDropShellNixGL, func() {})
 			}
 
 			/*
@@ -318,63 +311,19 @@ func main() {
 
 			argv := make([]string, 1, len(args))
 			if !flagDropShell {
-				argv[0] = app.Launcher
+				argv[0] = a.Launcher
 			} else {
 				argv[0] = shellPath
 			}
 			argv = append(argv, args[1:]...)
 
-			config := &fst.Config{
-				ID:      app.ID,
-				Command: argv,
-				Confinement: fst.ConfinementConfig{
-					AppID:    app.AppID,
-					Groups:   app.Groups,
-					Username: "fortify",
-					Inner:    path.Join("/data/data", app.ID),
-					Outer:    pathSet.homeDir,
-					Sandbox: &fst.SandboxConfig{
-						Hostname:      formatHostname(app.Name),
-						UserNS:        app.UserNS,
-						Net:           app.Net,
-						Dev:           app.Dev,
-						Syscall:       &bwrap.SyscallPolicy{DenyDevel: !app.Devel, Multiarch: app.Multiarch, Bluetooth: app.Bluetooth},
-						NoNewSession:  app.NoNewSession || flagDropShell,
-						MapRealUID:    app.MapRealUID,
-						DirectWayland: app.DirectWayland,
-						Filesystem: []*fst.FilesystemConfig{
-							{Src: path.Join(pathSet.nixPath, "store"), Dst: "/nix/store", Must: true},
-							{Src: pathSet.metaPath, Dst: path.Join(fst.Tmp, "app"), Must: true},
-							{Src: "/etc/resolv.conf"},
-							{Src: "/sys/block"},
-							{Src: "/sys/bus"},
-							{Src: "/sys/class"},
-							{Src: "/sys/dev"},
-							{Src: "/sys/devices"},
-						},
-						Link: [][2]string{
-							{app.CurrentSystem, "/run/current-system"},
-							{"/run/current-system/sw/bin", "/bin"},
-							{"/run/current-system/sw/bin", "/usr/bin"},
-						},
-						Etc:     path.Join(pathSet.cacheDir, "etc"),
-						AutoEtc: true,
-					},
-					ExtraPerms: []*fst.ExtraPermConfig{
-						{Path: dataHome, Execute: true},
-						{Ensure: true, Path: pathSet.baseDir, Read: true, Write: true, Execute: true},
-					},
-					SystemBus:   app.SystemBus,
-					SessionBus:  app.SessionBus,
-					Enablements: app.Enablements,
-				},
-			}
+			config := a.toFst(pathSet, argv, flagDropShell)
 
 			/*
 				Expose GPU devices.
 			*/
 
-			if app.GPU {
+			if a.GPU {
 				config.Confinement.Sandbox.Filesystem = append(config.Confinement.Sandbox.Filesystem,
 					&fst.FilesystemConfig{Src: path.Join(pathSet.nixPath, ".nixGL"), Dst: path.Join(fst.Tmp, "nixGL")})
 				appendGPUFilesystem(config)

cmd/fpkg/proc.go

@@ -11,14 +11,14 @@ import (
 
 func mustRunApp(ctx context.Context, config *fst.Config, beforeFail func()) {
 	rs := new(fst.RunState)
-	a := app.MustNew(std)
+	a := app.MustNew(ctx, std)
 
 	if sa, err := a.Seal(config); err != nil {
 		fmsg.PrintBaseError(err, "cannot seal app:")
 		rs.ExitCode = 1
 	} else {
 		// this updates ExitCode
-		app.PrintRunStateErr(rs, sa.Run(ctx, rs))
+		app.PrintRunStateErr(rs, sa.Run(rs))
 	}
 
 	if rs.ExitCode != 0 {

cmd/fpkg/test/configuration.nix

@@ -32,7 +32,7 @@
       echo 'output Virtual-1 res 1680x1050') > ~/.config/sway/config
 
       sway --validate
-      systemd-cat --identifier=sway sway && touch /tmp/sway-exit-ok
+      systemd-cat --identifier=session sway && touch /tmp/sway-exit-ok
     fi
   '';
 

cmd/fpkg/test/test.py

@@ -62,8 +62,8 @@ def check_state(name, enablements):
 
     config = instance['config']
 
-    if len(config['command']) != 1 or not (config['command'][0].startswith("/nix/store/")) or f"fortify-{name}-" not in (config['command'][0]):
-        raise Exception(f"unexpected command {instance['config']['command']}")
+    if len(config['args']) != 1 or not (config['args'][0].startswith("/nix/store/")) or f"fortify-{name}-" not in (config['args'][0]):
+        raise Exception(f"unexpected args {instance['config']['args']}")
 
     if config['confinement']['enablements'] != enablements:
         raise Exception(f"unexpected enablements {instance['config']['confinement']['enablements']}")

cmd/fpkg/with.go

@@ -6,18 +6,19 @@ import (
 	"strings"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
 )
 
 func withNixDaemon(
 	ctx context.Context,
 	action string, command []string, net bool, updateConfig func(config *fst.Config) *fst.Config,
-	app *bundleInfo, pathSet *appPathSet, dropShell bool, beforeFail func(),
+	app *appInfo, pathSet *appPathSet, dropShell bool, beforeFail func(),
 ) {
 	mustRunAppDropShell(ctx, updateConfig(&fst.Config{
-		ID: app.ID,
-		Command: []string{shellPath, "-lc", "rm -f /nix/var/nix/daemon-socket/socket && " +
+		ID:   app.ID,
+		Path: shellPath,
+		Args: []string{shellPath, "-lc", "rm -f /nix/var/nix/daemon-socket/socket && " +
 			// start nix-daemon
 			"nix-daemon --store / & " +
 			// wait for socket to appear
@@ -34,11 +35,11 @@ func withNixDaemon(
 			Inner:    path.Join("/data/data", app.ID),
 			Outer:    pathSet.homeDir,
 			Sandbox: &fst.SandboxConfig{
-				Hostname:     formatHostname(app.Name) + "-" + action,
-				UserNS:       true, // nix sandbox requires userns
-				Net:          net,
-				Syscall:      &bwrap.SyscallPolicy{Multiarch: true},
-				NoNewSession: dropShell,
+				Hostname: formatHostname(app.Name) + "-" + action,
+				Userns:   true, // nix sandbox requires userns
+				Net:      net,
+				Seccomp:  seccomp.FlagMultiarch,
+				Tty:      dropShell,
 				Filesystem: []*fst.FilesystemConfig{
 					{Src: pathSet.nixPath, Dst: "/nix", Write: true, Must: true},
 				},
@@ -61,19 +62,20 @@ func withNixDaemon(
 func withCacheDir(
 	ctx context.Context,
 	action string, command []string, workDir string,
-	app *bundleInfo, pathSet *appPathSet, dropShell bool, beforeFail func()) {
+	app *appInfo, pathSet *appPathSet, dropShell bool, beforeFail func()) {
 	mustRunAppDropShell(ctx, &fst.Config{
-		ID:      app.ID,
-		Command: []string{shellPath, "-lc", strings.Join(command, " && ")},
+		ID:   app.ID,
+		Path: shellPath,
+		Args: []string{shellPath, "-lc", strings.Join(command, " && ")},
 		Confinement: fst.ConfinementConfig{
 			AppID:    app.AppID,
 			Username: "nixos",
 			Inner:    path.Join("/data/data", app.ID, "cache"),
 			Outer:    pathSet.cacheDir, // this also ensures cacheDir via shim
 			Sandbox: &fst.SandboxConfig{
-				Hostname:     formatHostname(app.Name) + "-" + action,
-				Syscall:      &bwrap.SyscallPolicy{Multiarch: true},
-				NoNewSession: dropShell,
+				Hostname: formatHostname(app.Name) + "-" + action,
+				Seccomp:  seccomp.FlagMultiarch,
+				Tty:      dropShell,
 				Filesystem: []*fst.FilesystemConfig{
 					{Src: path.Join(workDir, "nix"), Dst: "/nix", Must: true},
 					{Src: workDir, Dst: path.Join(fst.Tmp, "bundle"), Must: true},
@@ -97,7 +99,7 @@ func withCacheDir(
 
 func mustRunAppDropShell(ctx context.Context, config *fst.Config, dropShell bool, beforeFail func()) {
 	if dropShell {
-		config.Command = []string{shellPath, "-l"}
+		config.Args = []string{shellPath, "-l"}
 		mustRunApp(ctx, config, beforeFail)
 		beforeFail()
 		internal.Exit(0)

dbus/dbus_test.go

@@ -1,14 +1,21 @@
 package dbus_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"fmt"
+	"os"
+	"os/exec"
 	"strings"
 	"testing"
 	"time"
 
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/helper"
+	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/sandbox"
 )
 
 func TestNew(t *testing.T) {
@@ -100,15 +107,20 @@ func TestProxy_Seal(t *testing.T) {
 }
 
 func TestProxy_Start_Wait_Close_String(t *testing.T) {
-	t.Run("sandboxed", func(t *testing.T) {
+	oldWaitDelay := helper.WaitDelay
+	helper.WaitDelay = 16 * time.Second
+	t.Cleanup(func() { helper.WaitDelay = oldWaitDelay })
+
+	t.Run("sandbox", func(t *testing.T) {
+		proxyName := dbus.ProxyName
+		dbus.ProxyName = os.Args[0]
+		t.Cleanup(func() { dbus.ProxyName = proxyName })
 		testProxyStartWaitCloseString(t, true)
 	})
-	t.Run("direct", func(t *testing.T) {
-		testProxyStartWaitCloseString(t, false)
-	})
+	t.Run("direct", func(t *testing.T) { testProxyStartWaitCloseString(t, false) })
 }
 
-func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
+func testProxyStartWaitCloseString(t *testing.T, useSandbox bool) {
 	for id, tc := range testCasePairs() {
 		// this test does not test errors
 		if tc[0].wantErr {
@@ -125,14 +137,33 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 		})
 
 		t.Run("proxy for "+id, func(t *testing.T) {
-			helper.InternalReplaceExecCommand(t)
-			overridePath(t)
-
 			p := dbus.New(tc[0].bus, tc[1].bus)
+			p.CommandContext = func(ctx context.Context) (cmd *exec.Cmd) {
+				return exec.CommandContext(ctx, os.Args[0], "-test.v",
+					"-test.run=TestHelperInit", "--", "init")
+			}
+			p.CmdF = func(v any) {
+				if useSandbox {
+					container := v.(*sandbox.Container)
+					if container.Args[0] != dbus.ProxyName {
+						panic(fmt.Sprintf("unexpected argv0 %q", os.Args[0]))
+					}
+					container.Args = append([]string{os.Args[0], "-test.run=TestHelperStub", "--"}, container.Args[1:]...)
+				} else {
+					cmd := v.(*exec.Cmd)
+					if cmd.Args[0] != dbus.ProxyName {
+						panic(fmt.Sprintf("unexpected argv0 %q", os.Args[0]))
+					}
+					cmd.Err = nil
+					cmd.Path = os.Args[0]
+					cmd.Args = append([]string{os.Args[0], "-test.run=TestHelperStub", "--"}, cmd.Args[1:]...)
+				}
+			}
+			p.FilterF = func(v []byte) []byte { return bytes.SplitN(v, []byte("TestHelperInit\n"), 2)[1] }
 			output := new(strings.Builder)
 
-			t.Run("unsealed behaviour of "+id, func(t *testing.T) {
-				t.Run("unsealed string of "+id, func(t *testing.T) {
+			t.Run("unsealed", func(t *testing.T) {
+				t.Run("string", func(t *testing.T) {
 					want := "(unsealed dbus proxy)"
 					if got := p.String(); got != want {
 						t.Errorf("String() = %v, want %v",
@@ -141,16 +172,16 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 					}
 				})
 
-				t.Run("unsealed start of "+id, func(t *testing.T) {
+				t.Run("start", func(t *testing.T) {
 					want := "proxy not sealed"
-					if err := p.Start(context.Background(), nil, sandbox); err == nil || err.Error() != want {
+					if err := p.Start(context.Background(), nil, useSandbox); err == nil || err.Error() != want {
 						t.Errorf("Start() error = %v, wantErr %q",
 							err, errors.New(want))
 						return
 					}
 				})
 
-				t.Run("unsealed wait of "+id, func(t *testing.T) {
+				t.Run("wait", func(t *testing.T) {
 					wantErr := "dbus: not started"
 					if err := p.Wait(); err == nil || err.Error() != wantErr {
 						t.Errorf("Wait() error = %v, wantErr %v",
@@ -168,7 +199,7 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 				}
 			})
 
-			t.Run("sealed behaviour of "+id, func(t *testing.T) {
+			t.Run("sealed", func(t *testing.T) {
 				want := strings.Join(append(tc[0].want, tc[1].want...), " ")
 				if got := p.String(); got != want {
 					t.Errorf("String() = %v, want %v",
@@ -176,17 +207,20 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 					return
 				}
 
-				t.Run("sealed start of "+id, func(t *testing.T) {
+				t.Run("start", func(t *testing.T) {
 					ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 					defer cancel()
 
-					if err := p.Start(ctx, output, sandbox); err != nil {
+					if err := p.Start(ctx, output, useSandbox); err != nil {
 						t.Fatalf("Start(nil, nil) error = %v",
 							err)
 					}
 
-					t.Run("started string of "+id, func(t *testing.T) {
-						wantSubstr := dbus.ProxyName + " --args="
+					t.Run("string", func(t *testing.T) {
+						wantSubstr := fmt.Sprintf("%s -test.run=TestHelperStub -- --args=3 --fd=4", os.Args[0])
+						if useSandbox {
+							wantSubstr = fmt.Sprintf(`argv: ["%s" "-test.run=TestHelperStub" "--" "--args=3" "--fd=4"], flags: 0x0, seccomp: 0x3e`, os.Args[0])
+						}
 						if got := p.String(); !strings.Contains(got, wantSubstr) {
 							t.Errorf("String() = %v, want %v",
 								p.String(), wantSubstr)
@@ -194,7 +228,7 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 						}
 					})
 
-					t.Run("started wait of "+id, func(t *testing.T) {
+					t.Run("wait", func(t *testing.T) {
 						p.Close()
 						if err := p.Wait(); err != nil {
 							t.Errorf("Wait() error = %v\noutput: %s",
@@ -207,10 +241,10 @@ func testProxyStartWaitCloseString(t *testing.T, sandbox bool) {
 	}
 }
 
-func overridePath(t *testing.T) {
-	proxyName := dbus.ProxyName
-	dbus.ProxyName = "/nonexistent-xdg-dbus-proxy"
-	t.Cleanup(func() {
-		dbus.ProxyName = proxyName
-	})
+func TestHelperInit(t *testing.T) {
+	if len(os.Args) != 5 || os.Args[4] != "init" {
+		return
+	}
+	sandbox.SetOutput(fmsg.Output{})
+	sandbox.Init(fmsg.Prepare, internal.InstallFmsg)
 }

dbus/proc.go

@@ -0,0 +1,178 @@
+package dbus
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"slices"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"git.gensokyo.uk/security/fortify/helper"
+	"git.gensokyo.uk/security/fortify/ldd"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+)
+
+// Start launches the D-Bus proxy.
+func (p *Proxy) Start(ctx context.Context, output io.Writer, useSandbox bool) error {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	if p.seal == nil {
+		return errors.New("proxy not sealed")
+	}
+
+	var h helper.Helper
+
+	c, cancel := context.WithCancelCause(ctx)
+	if !useSandbox {
+		h = helper.NewDirect(c, p.name, p.seal, true, argF, func(cmd *exec.Cmd) {
+			if p.CmdF != nil {
+				p.CmdF(cmd)
+			}
+			if output != nil {
+				cmd.Stdout, cmd.Stderr = output, output
+			}
+			cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+			cmd.Env = make([]string, 0)
+		}, nil)
+	} else {
+		toolPath := p.name
+		if filepath.Base(p.name) == p.name {
+			if s, err := exec.LookPath(p.name); err != nil {
+				return err
+			} else {
+				toolPath = s
+			}
+		}
+
+		var libPaths []string
+		if entries, err := ldd.ExecFilter(ctx, p.CommandContext, p.FilterF, toolPath); err != nil {
+			return err
+		} else {
+			libPaths = ldd.Path(entries)
+		}
+
+		h = helper.New(
+			c, toolPath,
+			p.seal, true,
+			argF, func(container *sandbox.Container) {
+				container.Seccomp |= seccomp.FlagMultiarch
+				container.Hostname = "fortify-dbus"
+				container.CommandContext = p.CommandContext
+				if output != nil {
+					container.Stdout, container.Stderr = output, output
+				}
+
+				if p.CmdF != nil {
+					p.CmdF(container)
+				}
+
+				// these lib paths are unpredictable, so mount them first so they cannot cover anything
+				for _, name := range libPaths {
+					container.Bind(name, name, 0)
+				}
+
+				// upstream bus directories
+				upstreamPaths := make([]string, 0, 2)
+				for _, as := range []string{p.session[0], p.system[0]} {
+					if len(as) > 0 && strings.HasPrefix(as, "unix:path=/") {
+						// leave / intact
+						upstreamPaths = append(upstreamPaths, path.Dir(as[10:]))
+					}
+				}
+				slices.Sort(upstreamPaths)
+				upstreamPaths = slices.Compact(upstreamPaths)
+				for _, name := range upstreamPaths {
+					container.Bind(name, name, 0)
+				}
+
+				// parent directories of bind paths
+				sockDirPaths := make([]string, 0, 2)
+				if d := path.Dir(p.session[1]); path.IsAbs(d) {
+					sockDirPaths = append(sockDirPaths, d)
+				}
+				if d := path.Dir(p.system[1]); path.IsAbs(d) {
+					sockDirPaths = append(sockDirPaths, d)
+				}
+				slices.Sort(sockDirPaths)
+				sockDirPaths = slices.Compact(sockDirPaths)
+				for _, name := range sockDirPaths {
+					container.Bind(name, name, sandbox.BindWritable)
+				}
+
+				// xdg-dbus-proxy bin path
+				binPath := path.Dir(toolPath)
+				container.Bind(binPath, binPath, 0)
+			}, nil)
+	}
+
+	if err := h.Start(); err != nil {
+		cancel(err)
+		return err
+	}
+
+	p.helper = h
+	p.ctx = c
+	p.cancel = cancel
+	return nil
+}
+
+var proxyClosed = errors.New("proxy closed")
+
+// Wait blocks until xdg-dbus-proxy exits and releases resources.
+func (p *Proxy) Wait() error {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	if p.helper == nil {
+		return errors.New("dbus: not started")
+	}
+
+	errs := make([]error, 3)
+
+	errs[0] = p.helper.Wait()
+	if p.cancel == nil &&
+		errors.Is(errs[0], context.Canceled) &&
+		errors.Is(context.Cause(p.ctx), proxyClosed) {
+		errs[0] = nil
+	}
+
+	// ensure socket removal so ephemeral directory is empty at revert
+	if err := os.Remove(p.session[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+		errs[1] = err
+	}
+	if p.sysP {
+		if err := os.Remove(p.system[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+			errs[2] = err
+		}
+	}
+
+	return errors.Join(errs...)
+}
+
+// Close cancels the context passed to the helper instance attached to xdg-dbus-proxy.
+func (p *Proxy) Close() {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	if p.cancel == nil {
+		panic("dbus: not started")
+	}
+	p.cancel(proxyClosed)
+	p.cancel = nil
+}
+
+func argF(argsFd, statFd int) []string {
+	if statFd == -1 {
+		return []string{"--args=" + strconv.Itoa(argsFd)}
+	} else {
+		return []string{"--args=" + strconv.Itoa(argsFd), "--fd=" + strconv.Itoa(statFd)}
+	}
+}

dbus/proxy.go

@@ -5,10 +5,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"os/exec"
 	"sync"
 
 	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
 )
 
 // ProxyName is the file name or path to the proxy program.
@@ -19,15 +19,18 @@ var ProxyName = "xdg-dbus-proxy"
 // Once sealed, configuration changes will no longer be possible and attempting to do so will result in a panic.
 type Proxy struct {
 	helper helper.Helper
-	bwrap  *bwrap.Config
 	ctx    context.Context
 	cancel context.CancelCauseFunc
 
 	name    string
 	session [2]string
 	system  [2]string
+	CmdF    func(any)
 	sysP    bool
 
+	CommandContext func(ctx context.Context) (cmd *exec.Cmd)
+	FilterF        func([]byte) []byte
+
 	seal io.WriterTo
 	lock sync.RWMutex
 }

dbus/run.go

@@ -1,175 +0,0 @@
-package dbus
-
-import (
-	"context"
-	"errors"
-	"io"
-	"os"
-	"os/exec"
-	"path"
-	"path/filepath"
-	"strconv"
-	"strings"
-
-	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/ldd"
-)
-
-// Start launches the D-Bus proxy.
-func (p *Proxy) Start(ctx context.Context, output io.Writer, sandbox bool) error {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	if p.seal == nil {
-		return errors.New("proxy not sealed")
-	}
-
-	var (
-		h helper.Helper
-
-		argF = func(argsFD, statFD int) []string {
-			if statFD == -1 {
-				return []string{"--args=" + strconv.Itoa(argsFD)}
-			} else {
-				return []string{"--args=" + strconv.Itoa(argsFD), "--fd=" + strconv.Itoa(statFD)}
-			}
-		}
-	)
-
-	if !sandbox {
-		h = helper.New(p.seal, p.name, argF)
-		// xdg-dbus-proxy does not need to inherit the environment
-		h.SetEnv(make([]string, 0))
-	} else {
-		// look up absolute path if name is just a file name
-		toolPath := p.name
-		if filepath.Base(p.name) == p.name {
-			if s, err := exec.LookPath(p.name); err != nil {
-				return err
-			} else {
-				toolPath = s
-			}
-		}
-
-		// resolve libraries by parsing ldd output
-		var proxyDeps []*ldd.Entry
-		if toolPath != "/nonexistent-xdg-dbus-proxy" {
-			if l, err := ldd.Exec(ctx, toolPath); err != nil {
-				return err
-			} else {
-				proxyDeps = l
-			}
-		}
-
-		bc := &bwrap.Config{
-			Unshare:       nil,
-			Hostname:      "fortify-dbus",
-			Chdir:         "/",
-			Syscall:       &bwrap.SyscallPolicy{DenyDevel: true, Multiarch: true},
-			Clearenv:      true,
-			NewSession:    true,
-			DieWithParent: true,
-		}
-
-		// resolve proxy socket directories
-		bindTarget := make(map[string]struct{}, 2)
-		for _, ps := range []string{p.session[1], p.system[1]} {
-			if pd := path.Dir(ps); len(pd) > 0 {
-				if pd[0] == '/' {
-					bindTarget[pd] = struct{}{}
-				}
-			}
-		}
-		for k := range bindTarget {
-			bc.Bind(k, k, false, true)
-		}
-
-		roBindTarget := make(map[string]struct{}, 2+1+len(proxyDeps))
-
-		// xdb-dbus-proxy bin and dependencies
-		roBindTarget[path.Dir(toolPath)] = struct{}{}
-		for _, ent := range proxyDeps {
-			if path.IsAbs(ent.Path) {
-				roBindTarget[path.Dir(ent.Path)] = struct{}{}
-			}
-			if path.IsAbs(ent.Name) {
-				roBindTarget[path.Dir(ent.Name)] = struct{}{}
-			}
-		}
-
-		// resolve upstream bus directories
-		for _, as := range []string{p.session[0], p.system[0]} {
-			if len(as) > 0 && strings.HasPrefix(as, "unix:path=/") {
-				// leave / intact
-				roBindTarget[path.Dir(as[10:])] = struct{}{}
-			}
-		}
-
-		for k := range roBindTarget {
-			bc.Bind(k, k)
-		}
-
-		h = helper.MustNewBwrap(bc, toolPath, true, p.seal, argF, nil, nil)
-		p.bwrap = bc
-	}
-
-	if output != nil {
-		h.Stdout(output).Stderr(output)
-	}
-	c, cancel := context.WithCancelCause(ctx)
-	if err := h.Start(c, true); err != nil {
-		cancel(err)
-		return err
-	}
-
-	p.helper = h
-	p.ctx = c
-	p.cancel = cancel
-	return nil
-}
-
-var proxyClosed = errors.New("proxy closed")
-
-// Wait blocks until xdg-dbus-proxy exits and releases resources.
-func (p *Proxy) Wait() error {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
-
-	if p.helper == nil {
-		return errors.New("dbus: not started")
-	}
-
-	errs := make([]error, 3)
-
-	errs[0] = p.helper.Wait()
-	if p.cancel == nil &&
-		errors.Is(errs[0], context.Canceled) &&
-		errors.Is(context.Cause(p.ctx), proxyClosed) {
-		errs[0] = nil
-	}
-
-	// ensure socket removal so ephemeral directory is empty at revert
-	if err := os.Remove(p.session[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
-		errs[1] = err
-	}
-	if p.sysP {
-		if err := os.Remove(p.system[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
-			errs[2] = err
-		}
-	}
-
-	return errors.Join(errs...)
-}
-
-// Close cancels the context passed to the helper instance attached to xdg-dbus-proxy.
-func (p *Proxy) Close() {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	if p.cancel == nil {
-		panic("dbus: not started")
-	}
-	p.cancel(proxyClosed)
-	p.cancel = nil
-}

dbus/samples_test.go

@@ -6,6 +6,12 @@ import (
 	"git.gensokyo.uk/security/fortify/dbus"
 )
 
+const (
+	sampleHostPath = "/tmp/bus"
+	sampleHostAddr = "unix:path=" + sampleHostPath
+	sampleBindPath = "/tmp/proxied_bus"
+)
+
 var samples = []dbusTestCase{
 	{
 		"org.chromium.Chromium", &dbus.Config{
@@ -19,10 +25,10 @@ var samples = []dbusTestCase{
 			Log:       false,
 			Filter:    true,
 		}, false, false,
-		[2]string{"unix:path=/run/user/1971/bus", "/tmp/fortify.1971/12622d846cc3fe7b4c10359d01f0eb47/bus"},
+		[2]string{sampleHostAddr, sampleBindPath},
 		[]string{
-			"unix:path=/run/user/1971/bus",
-			"/tmp/fortify.1971/12622d846cc3fe7b4c10359d01f0eb47/bus",
+			sampleHostAddr,
+			sampleBindPath,
 			"--filter",
 			"--talk=org.freedesktop.Notifications",
 			"--talk=org.freedesktop.FileManager1",
@@ -48,9 +54,10 @@ var samples = []dbusTestCase{
 			Log:       false,
 			Filter:    true,
 		}, false, false,
-		[2]string{"unix:path=/run/dbus/system_bus_socket", "/tmp/fortify.1971/12622d846cc3fe7b4c10359d01f0eb47/system_bus_socket"},
-		[]string{"unix:path=/run/dbus/system_bus_socket",
-			"/tmp/fortify.1971/12622d846cc3fe7b4c10359d01f0eb47/system_bus_socket",
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
 			"--filter",
 			"--talk=org.bluez",
 			"--talk=org.freedesktop.Avahi",
@@ -68,10 +75,10 @@ var samples = []dbusTestCase{
 			Log:       false,
 			Filter:    true,
 		}, false, false,
-		[2]string{"unix:path=/run/user/1971/bus", "/tmp/fortify.1971/34c24f16a0d791d28835ededaf446033/bus"},
+		[2]string{sampleHostAddr, sampleBindPath},
 		[]string{
-			"unix:path=/run/user/1971/bus",
-			"/tmp/fortify.1971/34c24f16a0d791d28835ededaf446033/bus",
+			sampleHostAddr,
+			sampleBindPath,
 			"--filter",
 			"--talk=org.freedesktop.Notifications",
 			"--talk=org.kde.StatusNotifierWatcher",
@@ -91,10 +98,10 @@ var samples = []dbusTestCase{
 			Log:       true,
 			Filter:    true,
 		}, false, false,
-		[2]string{"unix:path=/run/user/1971/bus", "/tmp/fortify.1971/5da7845287a936efbc2fa75d7d81e501/bus"},
+		[2]string{sampleHostAddr, sampleBindPath},
 		[]string{
-			"unix:path=/run/user/1971/bus",
-			"/tmp/fortify.1971/5da7845287a936efbc2fa75d7d81e501/bus",
+			sampleHostAddr,
+			sampleBindPath,
 			"--filter",
 			"--see=uk.gensokyo.CrashTestDummy1",
 			"--talk=org.freedesktop.Notifications",
@@ -114,10 +121,10 @@ var samples = []dbusTestCase{
 			Log:       true,
 			Filter:    true,
 		}, false, true,
-		[2]string{"unix:path=/run/user/1971/bus", "/tmp/fortify.1971/5da7845287a936efbc2fa75d7d81e501/bus"},
+		[2]string{sampleHostAddr, sampleBindPath},
 		[]string{
-			"unix:path=/run/user/1971/bus",
-			"/tmp/fortify.1971/5da7845287a936efbc2fa75d7d81e501/bus",
+			sampleHostAddr,
+			sampleBindPath,
 			"--filter",
 			"--see=uk.gensokyo.CrashTestDummy",
 			"--talk=org.freedesktop.Notifications",

dbus/stub_test.go

@@ -6,6 +6,4 @@ import (
 	"git.gensokyo.uk/security/fortify/helper"
 )
 
-func TestHelperChildStub(t *testing.T) {
-	helper.InternalChildStub()
-}
+func TestHelperStub(t *testing.T) { helper.InternalHelperStub() }

flake.lock

@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1736373539,
-        "narHash": "sha256-dinzAqCjenWDxuy+MqUQq0I4zUSfaCvN9rzuCmgMZJY=",
+        "lastModified": 1742234739,
+        "narHash": "sha256-zFL6zsf/5OztR1NSNQF33dvS1fL/BzVUjabZq4qrtY4=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "bd65bc3cde04c16755955630b344bc9e35272c56",
+        "rev": "f6af7280a3390e65c2ad8fd059cdc303426cbd59",
         "type": "github"
       },
       "original": {
@@ -23,16 +23,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1739333913,
-        "narHash": "sha256-JXt5FtySR+yBm5ny8zG/hX1IybF/7R66jZfXxXSb6wY=",
+        "lastModified": 1742512142,
+        "narHash": "sha256-8XfURTDxOm6+33swQJu/hx6xw1Tznl8vJJN5HwVqckg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "7d83f668aee9e41d574c398a9bb569047e8a3f5d",
+        "rev": "7105ae3957700a9646cc4b766f5815b23ed0c682",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-24.11-small",
+        "ref": "nixos-24.11",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -2,7 +2,7 @@
   description = "fortify sandbox tool and nixos module";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11-small";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
 
     home-manager = {
       url = "github:nix-community/home-manager/release-24.11";
@@ -27,7 +27,7 @@
       nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
     in
     {
-      nixosModules.fortify = import ./nixos.nix;
+      nixosModules.fortify = import ./nixos.nix self.packages;
 
       buildPackage = forAllSystems (
         system:
@@ -105,9 +105,20 @@
           default = fortify;
           fortify = pkgs.pkgsStatic.callPackage ./package.nix {
             inherit (pkgs)
-              bubblewrap
-              xdg-dbus-proxy
+              # passthru.buildInputs
+              go
+              gcc
+
+              # nativeBuildInputs
+              pkg-config
+              wayland-scanner
+              makeBinaryWrapper
+
+              # appPackages
               glibc
+              xdg-dbus-proxy
+
+              # fpkg
               zstd
               gnutar
               coreutils
@@ -115,7 +126,7 @@
           };
           fsu = pkgs.callPackage ./cmd/fsu/package.nix { inherit (self.packages.${system}) fortify; };
 
-          dist = pkgs.runCommand "${fortify.name}-dist" { inherit (self.devShells.${system}.default) buildInputs; } ''
+          dist = pkgs.runCommand "${fortify.name}-dist" { buildInputs = fortify.targetPkgs ++ [ pkgs.pkgsStatic.musl ]; } ''
             # go requires XDG_CACHE_HOME for the build cache
             export XDG_CACHE_HOME="$(mktemp -d)"
 
@@ -128,93 +139,21 @@
             export FORTIFY_VERSION="v${fortify.version}"
             ./dist/release.sh && mkdir $out && cp -v "dist/fortify-$FORTIFY_VERSION.tar.gz"* $out
           '';
-
-          fhs = pkgs.buildFHSEnv {
-            pname = "fortify-fhs";
-            inherit (fortify) version;
-            targetPkgs =
-              pkgs:
-              with pkgs;
-              [
-                go
-                gcc
-                pkg-config
-                wayland-scanner
-              ]
-              ++ (
-                with pkgs.pkgsStatic;
-                [
-                  musl
-                  libffi
-                  libseccomp
-                  acl
-                  wayland
-                  wayland-protocols
-                ]
-                ++ (with xorg; [
-                  libxcb
-                  libXau
-                  libXdmcp
-
-                  xorgproto
-                ])
-              );
-            extraOutputsToInstall = [ "dev" ];
-            profile = ''
-              export PKG_CONFIG_PATH="/usr/share/pkgconfig:$PKG_CONFIG_PATH"
-            '';
-          };
         }
       );
 
       devShells = forAllSystems (
         system:
         let
-          inherit (self.packages.${system}) fortify fhs;
+          inherit (self.packages.${system}) fortify;
           pkgs = nixpkgsFor.${system};
         in
         {
-          default = pkgs.mkShell {
-            buildInputs =
-              with pkgs;
-              [
-                go
-                gcc
-              ]
-              # buildInputs
-              ++ (
-                with pkgsStatic;
-                [
-                  musl
-                  libffi
-                  libseccomp
-                  acl
-                  wayland
-                  wayland-protocols
-                ]
-                ++ (with xorg; [
-                  libxcb
-                  libXau
-                  libXdmcp
-                ])
-              )
-              # nativeBuildInputs
-              ++ [
-                pkg-config
-                wayland-scanner
-                makeBinaryWrapper
-              ];
-          };
-
-          fhs = fhs.env;
-
-          withPackage = nixpkgsFor.${system}.mkShell {
-            buildInputs = [ self.packages.${system}.fortify ] ++ self.devShells.${system}.default.buildInputs;
-          };
+          default = pkgs.mkShell { buildInputs = fortify.targetPkgs; };
+          withPackage = pkgs.mkShell { buildInputs = [ fortify ] ++ fortify.targetPkgs; };
 
           generateDoc =
             let
-              pkgs = nixpkgsFor.${system};
               inherit (pkgs) lib;
 
               doc =
@@ -223,7 +162,7 @@
                     specialArgs = {
                       inherit pkgs;
                     };
-                    modules = [ ./options.nix ];
+                    modules = [ (import ./options.nix self.packages) ];
                   };
                   cleanEval = lib.filterAttrsRecursive (n: _: n != "_module") eval;
                 in
@@ -233,7 +172,7 @@
                 sed -i '/*Declared by:*/,+1 d' $out
               '';
             in
-            nixpkgsFor.${system}.mkShell {
+            pkgs.mkShell {
               shellHook = ''
                 exec cat ${docText} > options.md
               '';

fst/app.go

@@ -2,7 +2,6 @@
 package fst
 
 import (
-	"context"
 	"time"
 )
 
@@ -19,7 +18,7 @@ type App interface {
 
 type SealedApp interface {
 	// Run commits sealed system setup and starts the app process.
-	Run(ctx context.Context, rs *RunState) error
+	Run(rs *RunState) error
 }
 
 // RunState stores the outcome of a call to [SealedApp.Run].

fst/config.go

@@ -2,7 +2,7 @@ package fst
 
 import (
 	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
@@ -14,8 +14,11 @@ type Config struct {
 	// passed to wayland security-context-v1 as application ID
 	// and used as part of defaults in dbus session proxy
 	ID string `json:"id"`
-	// final argv, passed to init
-	Command []string `json:"command"`
+
+	// absolute path to executable file
+	Path string `json:"path,omitempty"`
+	// final args passed to container init
+	Args []string `json:"args"`
 
 	Confinement ConfinementConfig `json:"confinement"`
 }
@@ -26,13 +29,13 @@ type ConfinementConfig struct {
 	AppID int `json:"app_id"`
 	// list of supplementary groups to inherit
 	Groups []string `json:"groups"`
-	// passwd username in the sandbox, defaults to passwd name of target uid or chronos
+	// passwd username in container, defaults to passwd name of target uid or chronos
 	Username string `json:"username,omitempty"`
-	// home directory in sandbox, empty for outer
+	// home directory in container, empty for outer
 	Inner string `json:"home_inner"`
 	// home directory in init namespace
 	Outer string `json:"home"`
-	// bwrap sandbox confinement configuration
+	// abstract sandbox configuration
 	Sandbox *SandboxConfig `json:"sandbox"`
 	// extra acl ops, runs after everything else
 	ExtraPerms []*ExtraPermConfig `json:"extra_perms,omitempty"`
@@ -44,8 +47,8 @@ type ConfinementConfig struct {
 	// nil value makes session bus proxy assume built-in defaults
 	SessionBus *dbus.Config `json:"session_bus,omitempty"`
 
-	// system resources to expose to the sandbox
-	Enablements system.Enablements `json:"enablements"`
+	// system resources to expose to the container
+	Enablements system.Enablement `json:"enablements"`
 }
 
 type ExtraPermConfig struct {
@@ -76,24 +79,12 @@ func (e *ExtraPermConfig) String() string {
 	return string(buf)
 }
 
-type FilesystemConfig struct {
-	// mount point in sandbox, same as src if empty
-	Dst string `json:"dst,omitempty"`
-	// host filesystem path to make available to sandbox
-	Src string `json:"src"`
-	// write access
-	Write bool `json:"write,omitempty"`
-	// device access
-	Device bool `json:"dev,omitempty"`
-	// fail if mount fails
-	Must bool `json:"require,omitempty"`
-}
-
 // Template returns a fully populated instance of Config.
 func Template() *Config {
 	return &Config{
-		ID: "org.chromium.Chromium",
-		Command: []string{
+		ID:   "org.chromium.Chromium",
+		Path: "/run/current-system/sw/bin/chromium",
+		Args: []string{
 			"chromium",
 			"--ignore-gpu-blocklist",
 			"--disable-smooth-scrolling",
@@ -108,11 +99,13 @@ func Template() *Config {
 			Inner:    "/var/lib/fortify",
 			Sandbox: &SandboxConfig{
 				Hostname:      "localhost",
-				UserNS:        true,
+				Devel:         true,
+				Userns:        true,
 				Net:           true,
 				Dev:           true,
-				Syscall:       &bwrap.SyscallPolicy{DenyDevel: true, Multiarch: true},
-				NoNewSession:  true,
+				Seccomp:       seccomp.FlagMultiarch,
+				Tty:           true,
+				Multiarch:     true,
 				MapRealUID:    true,
 				DirectWayland: false,
 				// example API credentials pulled from Google Chrome
@@ -131,10 +124,10 @@ func Template() *Config {
 						Dst: "/data/data/org.chromium.Chromium", Write: true, Must: true},
 					{Src: "/dev/dri", Device: true},
 				},
-				Link:     [][2]string{{"/run/user/65534", "/run/user/150"}},
-				Etc:      "/etc",
-				AutoEtc:  true,
-				Override: []string{"/var/run/nscd"},
+				Link:    [][2]string{{"/run/user/65534", "/run/user/150"}},
+				Etc:     "/etc",
+				AutoEtc: true,
+				Cover:   []string{"/var/run/nscd"},
 			},
 			ExtraPerms: []*ExtraPermConfig{
 				{Path: "/var/lib/fortify/u0", Ensure: true, Execute: true},
@@ -160,7 +153,7 @@ func Template() *Config {
 				Log:       false,
 				Filter:    true,
 			},
-			Enablements: system.EWayland.Mask() | system.EDBus.Mask() | system.EPulse.Mask(),
+			Enablements: system.EWayland | system.EDBus | system.EPulse,
 		},
 	}
 }

fst/sandbox.go

@@ -4,125 +4,149 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
+	"maps"
 	"path"
+	"slices"
+	"syscall"
 
 	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
 )
 
 // SandboxConfig describes resources made available to the sandbox.
-type SandboxConfig struct {
-	// unix hostname within sandbox
-	Hostname string `json:"hostname,omitempty"`
-	// allow userns within sandbox
-	UserNS bool `json:"userns,omitempty"`
-	// share net namespace
-	Net bool `json:"net,omitempty"`
-	// share all devices
-	Dev bool `json:"dev,omitempty"`
-	// seccomp syscall filter policy
-	Syscall *bwrap.SyscallPolicy `json:"syscall"`
-	// do not run in new session
-	NoNewSession bool `json:"no_new_session,omitempty"`
-	// map target user uid to privileged user uid in the user namespace
-	MapRealUID bool `json:"map_real_uid"`
-	// direct access to wayland socket; when this gets set no attempt is made to attach security-context-v1
-	// and the bare socket is mounted to the sandbox
-	DirectWayland bool `json:"direct_wayland,omitempty"`
+type (
+	SandboxConfig struct {
+		// container hostname
+		Hostname string `json:"hostname,omitempty"`
 
-	// final environment variables
-	Env map[string]string `json:"env"`
-	// sandbox host filesystem access
-	Filesystem []*FilesystemConfig `json:"filesystem"`
-	// symlinks created inside the sandbox
-	Link [][2]string `json:"symlink"`
-	// read-only /etc directory
-	Etc string `json:"etc,omitempty"`
-	// automatically set up /etc symlinks
-	AutoEtc bool `json:"auto_etc"`
-	// mount tmpfs over these paths,
-	// runs right before [ConfinementConfig.ExtraPerms]
-	Override []string `json:"override"`
-}
+		// extra seccomp flags
+		Seccomp seccomp.SyscallOpts `json:"seccomp"`
+		// allow ptrace and friends
+		Devel bool `json:"devel,omitempty"`
+		// allow userns creation in container
+		Userns bool `json:"userns,omitempty"`
+		// share host net namespace
+		Net bool `json:"net,omitempty"`
+		// expose main process tty
+		Tty bool `json:"tty,omitempty"`
+		// allow multiarch
+		Multiarch bool `json:"multiarch,omitempty"`
 
-// SandboxSys encapsulates system functions used during the creation of [bwrap.Config].
-type SandboxSys interface {
-	Geteuid() int
-	Paths() Paths
-	ReadDir(name string) ([]fs.DirEntry, error)
-	EvalSymlinks(path string) (string, error)
+		// initial process environment variables
+		Env map[string]string `json:"env"`
+		// map target user uid to privileged user uid in the user namespace
+		MapRealUID bool `json:"map_real_uid"`
 
-	Println(v ...any)
-	Printf(format string, v ...any)
-}
+		// expose all devices
+		Dev bool `json:"dev,omitempty"`
+		// container host filesystem bind mounts
+		Filesystem []*FilesystemConfig `json:"filesystem"`
+		// create symlinks inside container filesystem
+		Link [][2]string `json:"symlink"`
 
-// Bwrap returns the address of the corresponding bwrap.Config to s.
-// Note that remaining tmpfs entries must be queued by the caller prior to launch.
-func (s *SandboxConfig) Bwrap(sys SandboxSys, uid *int) (*bwrap.Config, error) {
+		// direct access to wayland socket; when this gets set no attempt is made to attach security-context-v1
+		// and the bare socket is mounted to the sandbox
+		DirectWayland bool `json:"direct_wayland,omitempty"`
+
+		// read-only /etc directory
+		Etc string `json:"etc,omitempty"`
+		// automatically set up /etc symlinks
+		AutoEtc bool `json:"auto_etc"`
+		// cover these paths or create them if they do not already exist
+		Cover []string `json:"cover"`
+	}
+
+	// SandboxSys encapsulates system functions used during [sandbox.Container] initialisation.
+	SandboxSys interface {
+		Getuid() int
+		Getgid() int
+		Paths() Paths
+		ReadDir(name string) ([]fs.DirEntry, error)
+		EvalSymlinks(path string) (string, error)
+
+		Println(v ...any)
+		Printf(format string, v ...any)
+	}
+
+	// FilesystemConfig is a representation of [sandbox.BindMount].
+	FilesystemConfig struct {
+		// mount point in container, same as src if empty
+		Dst string `json:"dst,omitempty"`
+		// host filesystem path to make available to the container
+		Src string `json:"src"`
+		// do not mount filesystem read-only
+		Write bool `json:"write,omitempty"`
+		// do not disable device files
+		Device bool `json:"dev,omitempty"`
+		// fail if the bind mount cannot be established for any reason
+		Must bool `json:"require,omitempty"`
+	}
+)
+
+// ToContainer initialises [sandbox.Params] via [SandboxConfig].
+// Note that remaining container setup must be queued by the [App] implementation.
+func (s *SandboxConfig) ToContainer(sys SandboxSys, uid, gid *int) (*sandbox.Params, map[string]string, error) {
 	if s == nil {
-		return nil, errors.New("nil sandbox config")
+		return nil, nil, syscall.EBADE
 	}
 
-	if s.Syscall == nil {
-		sys.Println("syscall filter not configured, PROCEED WITH CAUTION")
-	}
-
-	if !s.MapRealUID {
-		// mapped uid defaults to 65534 to work around file ownership checks due to a bwrap limitation
-		*uid = 65534
-	} else {
-		// some programs fail to connect to dbus session running as a different uid, so a separate workaround
-		// is introduced to map priv-side caller uid in namespace
-		*uid = sys.Geteuid()
-	}
-
-	conf := (&bwrap.Config{
-		Net:      s.Net,
-		UserNS:   s.UserNS,
-		UID:      uid,
-		GID:      uid,
+	container := &sandbox.Params{
 		Hostname: s.Hostname,
-		Clearenv: true,
-		SetEnv:   s.Env,
+		Ops:      new(sandbox.Ops),
+		Seccomp:  s.Seccomp,
+	}
 
-		/* this is only 4 KiB of memory on a 64-bit system,
-		permissive defaults on NixOS results in around 100 entries
-		so this capacity should eliminate copies for most setups */
-		Filesystem: make([]bwrap.FSBuilder, 0, 256),
+	/* this is only 4 KiB of memory on a 64-bit system,
+	permissive defaults on NixOS results in around 100 entries
+	so this capacity should eliminate copies for most setups */
+	*container.Ops = slices.Grow(*container.Ops, 1<<8)
 
-		Syscall:       s.Syscall,
-		NewSession:    !s.NoNewSession,
-		DieWithParent: true,
-		AsInit:        true,
+	if s.Devel {
+		container.Flags |= sandbox.FAllowDevel
+	}
+	if s.Userns {
+		container.Flags |= sandbox.FAllowUserns
+	}
+	if s.Net {
+		container.Flags |= sandbox.FAllowNet
+	}
+	if s.Tty {
+		container.Flags |= sandbox.FAllowTTY
+	}
 
-		// initialise unconditionally as Once cannot be justified
-		// for saving such a miniscule amount of memory
-		Chmod: make(bwrap.ChmodConfig),
-	}).
-		Procfs("/proc").
-		Tmpfs(Tmp, 4*1024)
+	if s.MapRealUID {
+		/* some programs fail to connect to dbus session running as a different uid
+		so this workaround is introduced to map priv-side caller uid in container */
+		container.Uid = sys.Getuid()
+		*uid = container.Uid
+		container.Gid = sys.Getgid()
+		*gid = container.Gid
+	} else {
+		*uid = sandbox.OverflowUid()
+		*gid = sandbox.OverflowGid()
+	}
+
+	container.
+		Proc("/proc").
+		Tmpfs(Tmp, 1<<12, 0755)
 
 	if !s.Dev {
-		conf.DevTmpfs("/dev").Mqueue("/dev/mqueue")
+		container.Dev("/dev").Mqueue("/dev/mqueue")
 	} else {
-		conf.Bind("/dev", "/dev", false, true, true)
+		container.Bind("/dev", "/dev", sandbox.BindDevice)
 	}
 
-	if !s.AutoEtc {
-		if s.Etc == "" {
-			conf.Dir("/etc")
-		} else {
-			conf.Bind(s.Etc, "/etc")
-		}
-	}
-
-	// retrieve paths and hide them if they're made available in the sandbox
+	/* retrieve paths and hide them if they're made available in the sandbox;
+	this feature tries to improve user experience of permissive defaults, and
+	to warn about issues in custom configuration; it is NOT a security feature
+	and should not be treated as such, ALWAYS be careful with what you bind */
 	var hidePaths []string
 	sc := sys.Paths()
 	hidePaths = append(hidePaths, sc.RuntimePath, sc.SharePath)
 	_, systemBusAddr := dbus.Address()
 	if entries, err := dbus.Parse([]byte(systemBusAddr)); err != nil {
-		return nil, err
+		return nil, nil, err
 	} else {
 		// there is usually only one, do not preallocate
 		for _, entry := range entries {
@@ -148,7 +172,7 @@ func (s *SandboxConfig) Bwrap(sys SandboxSys, uid *int) (*bwrap.Config, error) {
 	hidePathMatch := make([]bool, len(hidePaths))
 	for i := range hidePaths {
 		if err := evalSymlinks(sys, &hidePaths[i]); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 
@@ -158,19 +182,19 @@ func (s *SandboxConfig) Bwrap(sys SandboxSys, uid *int) (*bwrap.Config, error) {
 		}
 
 		if !path.IsAbs(c.Src) {
-			return nil, fmt.Errorf("src path %q is not absolute", c.Src)
+			return nil, nil, fmt.Errorf("src path %q is not absolute", c.Src)
 		}
 
 		dest := c.Dst
 		if c.Dst == "" {
 			dest = c.Src
 		} else if !path.IsAbs(dest) {
-			return nil, fmt.Errorf("dst path %q is not absolute", dest)
+			return nil, nil, fmt.Errorf("dst path %q is not absolute", dest)
 		}
 
 		srcH := c.Src
 		if err := evalSymlinks(sys, &srcH); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 
 		for i := range hidePaths {
@@ -180,54 +204,69 @@ func (s *SandboxConfig) Bwrap(sys SandboxSys, uid *int) (*bwrap.Config, error) {
 			}
 
 			if ok, err := deepContainsH(srcH, hidePaths[i]); err != nil {
-				return nil, err
+				return nil, nil, err
 			} else if ok {
 				hidePathMatch[i] = true
 				sys.Printf("hiding paths from %q", c.Src)
 			}
 		}
 
-		conf.Bind(c.Src, dest, !c.Must, c.Write, c.Device)
+		var flags int
+		if c.Write {
+			flags |= sandbox.BindWritable
+		}
+		if c.Device {
+			flags |= sandbox.BindDevice | sandbox.BindWritable
+		}
+		if !c.Must {
+			flags |= sandbox.BindOptional
+		}
+		container.Bind(c.Src, dest, flags)
 	}
 
-	// hide marked paths before setting up shares
+	// cover matched paths
 	for i, ok := range hidePathMatch {
 		if ok {
-			conf.Tmpfs(hidePaths[i], 8192)
+			container.Tmpfs(hidePaths[i], 1<<13, 0755)
 		}
 	}
 
 	for _, l := range s.Link {
-		conf.Symlink(l[0], l[1])
+		container.Link(l[0], l[1])
 	}
 
-	if s.AutoEtc {
-		etc := s.Etc
-		if etc == "" {
-			etc = "/etc"
+	// perf: this might work better if implemented as a setup op in container init
+	if !s.AutoEtc {
+		if s.Etc != "" {
+			container.Bind(s.Etc, "/etc", 0)
 		}
-		conf.Bind(etc, Tmp+"/etc")
+	} else {
+		etcPath := s.Etc
+		if etcPath == "" {
+			etcPath = "/etc"
+		}
+		container.Bind(etcPath, Tmp+"/etc", 0)
 
-		// link host /etc contents to prevent passwd/group from being overwritten
-		if d, err := sys.ReadDir(etc); err != nil {
-			return nil, err
+		// link host /etc contents to prevent dropping passwd/group bind mounts
+		if d, err := sys.ReadDir(etcPath); err != nil {
+			return nil, nil, err
 		} else {
 			for _, ent := range d {
-				name := ent.Name()
-				switch name {
+				n := ent.Name()
+				switch n {
 				case "passwd":
 				case "group":
 
 				case "mtab":
-					conf.Symlink("/proc/mounts", "/etc/"+name)
+					container.Link("/proc/mounts", "/etc/"+n)
 				default:
-					conf.Symlink(Tmp+"/etc/"+name, "/etc/"+name)
+					container.Link(Tmp+"/etc/"+n, "/etc/"+n)
 				}
 			}
 		}
 	}
 
-	return conf, nil
+	return container, maps.Clone(s.Env), nil
 }
 
 func evalSymlinks(sys SandboxSys, v *string) error {

go.mod

@@ -1,3 +1,3 @@
 module git.gensokyo.uk/security/fortify
 
-go 1.22
+go 1.23

helper/args_test.go

@@ -9,7 +9,7 @@ import (
 	"git.gensokyo.uk/security/fortify/helper"
 )
 
-func Test_argsFD_String(t *testing.T) {
+func Test_argsFd_String(t *testing.T) {
 	wantString := strings.Join(wantArgs, " ")
 	if got := argsWt.(fmt.Stringer).String(); got != wantString {
 		t.Errorf("String(): got %v; want %v",

helper/bwrap.go

@@ -1,96 +0,0 @@
-package helper
-
-import (
-	"context"
-	"errors"
-	"io"
-	"os"
-	"slices"
-	"strconv"
-	"sync"
-	"syscall"
-
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/helper/proc"
-)
-
-// BubblewrapName is the file name or path to bubblewrap.
-var BubblewrapName = "bwrap"
-
-type bubblewrap struct {
-	// final args fd of bwrap process
-	argsFd uintptr
-
-	// name of the command to run in bwrap
-	name string
-
-	// whether to set process group id
-	setpgid bool
-
-	lock sync.RWMutex
-	*helperCmd
-}
-
-func (b *bubblewrap) Start(ctx context.Context, stat bool) error {
-	b.lock.Lock()
-	defer b.lock.Unlock()
-
-	// Check for doubled Start calls before we defer failure cleanup. If the prior
-	// call to Start succeeded, we don't want to spuriously close its pipes.
-	if b.Cmd != nil && b.Cmd.Process != nil {
-		return errors.New("exec: already started")
-	}
-
-	args := b.finalise(ctx, stat)
-	if b.setpgid {
-		b.Cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
-	}
-
-	b.Cmd.Args = slices.Grow(b.Cmd.Args, 4+len(args))
-	b.Cmd.Args = append(b.Cmd.Args, "--args", strconv.Itoa(int(b.argsFd)), "--", b.name)
-	b.Cmd.Args = append(b.Cmd.Args, args...)
-	return proc.Fulfill(ctx, b.Cmd, b.files, b.extraFiles)
-}
-
-// MustNewBwrap initialises a new Bwrap instance with wt as the null-terminated argument writer.
-// If wt is nil, the child process spawned by bwrap will not get an argument pipe.
-// Function argF returns an array of arguments passed directly to the child process.
-func MustNewBwrap(
-	conf *bwrap.Config, name string, setpgid bool,
-	wt io.WriterTo, argF func(argsFD, statFD int) []string,
-	extraFiles []*os.File,
-	syncFd *os.File,
-) Helper {
-	b, err := NewBwrap(conf, name, setpgid, wt, argF, extraFiles, syncFd)
-	if err != nil {
-		panic(err.Error())
-	} else {
-		return b
-	}
-}
-
-// NewBwrap initialises a new Bwrap instance with wt as the null-terminated argument writer.
-// If wt is nil, the child process spawned by bwrap will not get an argument pipe.
-// Function argF returns an array of arguments passed directly to the child process.
-func NewBwrap(
-	conf *bwrap.Config, name string, setpgid bool,
-	wt io.WriterTo, argF func(argsFd, statFd int) []string,
-	extraFiles []*os.File,
-	syncFd *os.File,
-) (Helper, error) {
-	b := new(bubblewrap)
-
-	b.name = name
-	b.setpgid = setpgid
-	b.helperCmd = newHelperCmd(b, BubblewrapName, wt, argF, extraFiles)
-
-	if v, err := NewCheckedArgs(conf.Args(syncFd, b.extraFiles, &b.files)); err != nil {
-		return nil, err
-	} else {
-		f := proc.NewWriterTo(v)
-		b.argsFd = proc.InitFile(f, b.extraFiles)
-		b.files = append(b.files, f)
-	}
-
-	return b, nil
-}

helper/bwrap/arg.go

@@ -1,72 +0,0 @@
-package bwrap
-
-import (
-	"os"
-	"slices"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-)
-
-type Builder interface {
-	Len() int
-	Append(args *[]string)
-}
-
-type FSBuilder interface {
-	Path() string
-	Builder
-}
-
-type FDBuilder interface {
-	proc.File
-	Builder
-}
-
-// Args returns a slice of bwrap args corresponding to c.
-func (c *Config) Args(syncFd *os.File, extraFiles *proc.ExtraFilesPre, files *[]proc.File) (args []string) {
-	builders := []Builder{
-		c.boolArgs(),
-		c.intArgs(),
-		c.stringArgs(),
-		c.pairArgs(),
-		c.seccompArgs(),
-		newFile(SyncFd.String(), syncFd),
-	}
-
-	builders = slices.Grow(builders, len(c.Filesystem)+1)
-	for _, f := range c.Filesystem {
-		builders = append(builders, f)
-	}
-	builders = append(builders, c.Chmod)
-
-	argc := 0
-	fc := 0
-	for _, b := range builders {
-		l := b.Len()
-		if l < 1 {
-			continue
-		}
-		argc += l
-
-		if f, ok := b.(FDBuilder); ok {
-			fc++
-			proc.InitFile(f, extraFiles)
-		}
-	}
-	fc++ // allocate extra slot for stat fd
-
-	args = make([]string, 0, argc)
-	*files = slices.Grow(*files, fc)
-	for _, b := range builders {
-		if b.Len() < 1 {
-			continue
-		}
-		b.Append(&args)
-
-		if f, ok := b.(FDBuilder); ok {
-			*files = append(*files, f)
-		}
-	}
-
-	return
-}

helper/bwrap/builder.go

@@ -1,199 +0,0 @@
-package bwrap
-
-import (
-	"os"
-)
-
-/*
-Bind binds mount src on host to dest in sandbox.
-
-Bind(src, dest) bind mount host path readonly on sandbox
-(--ro-bind SRC DEST).
-Bind(src, dest, true) equal to ROBind but ignores non-existent host path
-(--ro-bind-try SRC DEST).
-
-Bind(src, dest, false, true) bind mount host path on sandbox.
-(--bind SRC DEST).
-Bind(src, dest, true, true) equal to Bind but ignores non-existent host path
-(--bind-try SRC DEST).
-
-Bind(src, dest, false, true, true) bind mount host path on sandbox, allowing device access
-(--dev-bind SRC DEST).
-Bind(src, dest, true, true, true) equal to DevBind but ignores non-existent host path
-(--dev-bind-try SRC DEST).
-*/
-func (c *Config) Bind(src, dest string, opts ...bool) *Config {
-	var (
-		try   bool
-		write bool
-		dev   bool
-	)
-
-	if len(opts) > 0 {
-		try = opts[0]
-	}
-	if len(opts) > 1 {
-		write = opts[1]
-	}
-	if len(opts) > 2 {
-		dev = opts[2]
-	}
-
-	if dev {
-		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{DevBindTry.String(), src, dest})
-		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{DevBind.String(), src, dest})
-		}
-		return c
-	} else if write {
-		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{BindTry.String(), src, dest})
-		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{Bind.String(), src, dest})
-		}
-		return c
-	} else {
-		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{ROBindTry.String(), src, dest})
-		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{ROBind.String(), src, dest})
-		}
-		return c
-	}
-}
-
-// WriteFile copy from FD to destination DEST
-// (--file FD DEST)
-func (c *Config) WriteFile(name string, data []byte) *Config {
-	c.Filesystem = append(c.Filesystem, &DataConfig{Dest: name, Data: data, Type: DataWrite})
-	return c
-}
-
-/*
-CopyBind copy from FD to file which is readonly bind-mounted on DEST
-(--ro-bind-data FD DEST)
-
-CopyBind(dest, payload, true) copy from FD to file which is bind-mounted on DEST
-(--bind-data FD DEST)
-*/
-func (c *Config) CopyBind(dest string, payload []byte, opts ...bool) *Config {
-	var p *[]byte
-	c.CopyBindRef(dest, &p, opts...)
-	*p = payload
-	return c
-}
-
-// CopyBindRef is the same as CopyBind but writes the address of DataConfig.Data.
-func (c *Config) CopyBindRef(dest string, payloadRef **[]byte, opts ...bool) *Config {
-	t := DataROBind
-	if len(opts) > 0 && opts[0] {
-		t = DataBind
-	}
-	d := &DataConfig{Dest: dest, Type: t}
-	*payloadRef = &d.Data
-
-	c.Filesystem = append(c.Filesystem, d)
-	return c
-}
-
-// Dir create dir in sandbox
-// (--dir DEST)
-func (c *Config) Dir(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{Dir.String(), dest})
-	return c
-}
-
-// RemountRO remount path as readonly; does not recursively remount
-// (--remount-ro DEST)
-func (c *Config) RemountRO(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{RemountRO.String(), dest})
-	return c
-}
-
-// Procfs mount new procfs in sandbox
-// (--proc DEST)
-func (c *Config) Procfs(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{Procfs.String(), dest})
-	return c
-}
-
-// DevTmpfs mount new dev in sandbox
-// (--dev DEST)
-func (c *Config) DevTmpfs(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{DevTmpfs.String(), dest})
-	return c
-}
-
-// Mqueue mount new mqueue in sandbox
-// (--mqueue DEST)
-func (c *Config) Mqueue(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{Mqueue.String(), dest})
-	return c
-}
-
-// Tmpfs mount new tmpfs in sandbox
-// (--tmpfs DEST)
-func (c *Config) Tmpfs(dest string, size int, perm ...os.FileMode) *Config {
-	tmpfs := &PermConfig[*TmpfsConfig]{Inner: &TmpfsConfig{Dir: dest}}
-	if size >= 0 {
-		tmpfs.Inner.Size = size
-	}
-	if len(perm) == 1 {
-		tmpfs.Mode = &perm[0]
-	}
-	c.Filesystem = append(c.Filesystem, tmpfs)
-	return c
-}
-
-// Overlay mount overlayfs on DEST, with writes going to an invisible tmpfs
-// (--tmp-overlay DEST)
-func (c *Config) Overlay(dest string, src ...string) *Config {
-	c.Filesystem = append(c.Filesystem, &OverlayConfig{Src: src, Dest: dest})
-	return c
-}
-
-// Join mount overlayfs read-only on DEST
-// (--ro-overlay DEST)
-func (c *Config) Join(dest string, src ...string) *Config {
-	c.Filesystem = append(c.Filesystem, &OverlayConfig{Src: src, Dest: dest, Persist: new([2]string)})
-	return c
-}
-
-// Persist mount overlayfs on DEST, with RWSRC as the host path for writes and
-// WORKDIR an empty directory on the same filesystem as RWSRC
-// (--overlay RWSRC WORKDIR DEST)
-func (c *Config) Persist(dest, rwsrc, workdir string, src ...string) *Config {
-	if rwsrc == "" || workdir == "" {
-		panic("persist called without required paths")
-	}
-	c.Filesystem = append(c.Filesystem, &OverlayConfig{Src: src, Dest: dest, Persist: &[2]string{rwsrc, workdir}})
-	return c
-}
-
-// Symlink create symlink within sandbox
-// (--symlink SRC DEST)
-func (c *Config) Symlink(src, dest string, perm ...os.FileMode) *Config {
-	symlink := &PermConfig[SymlinkConfig]{Inner: SymlinkConfig{src, dest}}
-	if len(perm) == 1 {
-		symlink.Mode = &perm[0]
-	}
-	c.Filesystem = append(c.Filesystem, symlink)
-	return c
-}
-
-// SetUID sets custom uid in the sandbox, requires new user namespace (--uid UID).
-func (c *Config) SetUID(uid int) *Config {
-	if uid >= 0 {
-		c.UID = &uid
-	}
-	return c
-}
-
-// SetGID sets custom gid in the sandbox, requires new user namespace (--gid GID).
-func (c *Config) SetGID(gid int) *Config {
-	if gid >= 0 {
-		c.GID = &gid
-	}
-	return c
-}

helper/bwrap/config.go

@@ -1,104 +0,0 @@
-package bwrap
-
-type Config struct {
-	// unshare every namespace we support by default if nil
-	// (--unshare-all)
-	Unshare *UnshareConfig `json:"unshare,omitempty"`
-	// retain the network namespace (can only combine with nil Unshare)
-	// (--share-net)
-	Net bool `json:"net"`
-
-	// disable further use of user namespaces inside sandbox and fail unless
-	// further use of user namespace inside sandbox is disabled if false
-	// (--disable-userns) (--assert-userns-disabled)
-	UserNS bool `json:"userns"`
-
-	// custom uid in the sandbox, requires new user namespace
-	// (--uid UID)
-	UID *int `json:"uid,omitempty"`
-	// custom gid in the sandbox, requires new user namespace
-	// (--gid GID)
-	GID *int `json:"gid,omitempty"`
-	// custom hostname in the sandbox, requires new uts namespace
-	// (--hostname NAME)
-	Hostname string `json:"hostname,omitempty"`
-
-	// change directory
-	// (--chdir DIR)
-	Chdir string `json:"chdir,omitempty"`
-	// unset all environment variables
-	// (--clearenv)
-	Clearenv bool `json:"clearenv"`
-	// set environment variable
-	// (--setenv VAR VALUE)
-	SetEnv map[string]string `json:"setenv,omitempty"`
-	// unset environment variables
-	// (--unsetenv VAR)
-	UnsetEnv []string `json:"unsetenv,omitempty"`
-
-	// take a lock on file while sandbox is running
-	// (--lock-file DEST)
-	LockFile []string `json:"lock_file,omitempty"`
-
-	// ordered filesystem args
-	Filesystem []FSBuilder `json:"filesystem,omitempty"`
-
-	// change permissions (must already exist)
-	// (--chmod OCTAL PATH)
-	Chmod ChmodConfig `json:"chmod,omitempty"`
-
-	// load and use seccomp rules from FD (not repeatable)
-	// (--seccomp FD)
-	Syscall *SyscallPolicy
-
-	// create a new terminal session
-	// (--new-session)
-	NewSession bool `json:"new_session"`
-	// kills with SIGKILL child process (COMMAND) when bwrap or bwrap's parent dies.
-	// (--die-with-parent)
-	DieWithParent bool `json:"die_with_parent"`
-	// do not install a reaper process with PID=1
-	// (--as-pid-1)
-	AsInit bool `json:"as_init"`
-
-	/* unmapped options include:
-	    --unshare-user-try           Create new user namespace if possible else continue by skipping it
-	    --unshare-cgroup-try         Create new cgroup namespace if possible else continue by skipping it
-	    --userns FD                  Use this user namespace (cannot combine with --unshare-user)
-	    --userns2 FD                 After setup switch to this user namespace, only useful with --userns
-	    --pidns FD                   Use this pid namespace (as parent namespace if using --unshare-pid)
-	    --bind-fd FD DEST            Bind open directory or path fd on DEST
-	    --ro-bind-fd FD DEST         Bind open directory or path fd read-only on DEST
-	    --exec-label LABEL           Exec label for the sandbox
-	    --file-label LABEL           File label for temporary sandbox content
-	    --add-seccomp-fd FD          Load and use seccomp rules from FD (repeatable)
-	    --block-fd FD                Block on FD until some data to read is available
-	    --userns-block-fd FD         Block on FD until the user namespace is ready
-	    --info-fd FD                 Write information about the running container to FD
-	    --json-status-fd FD          Write container status to FD as multiple JSON documents
-	    --cap-add CAP                Add cap CAP when running as privileged user
-	    --cap-drop CAP               Drop cap CAP when running as privileged user
-
-	among which --args is used internally for passing arguments */
-}
-
-type UnshareConfig struct {
-	// (--unshare-user)
-	// create new user namespace
-	User bool `json:"user"`
-	// (--unshare-ipc)
-	// create new ipc namespace
-	IPC bool `json:"ipc"`
-	// (--unshare-pid)
-	// create new pid namespace
-	PID bool `json:"pid"`
-	// (--unshare-net)
-	// create new network namespace
-	Net bool `json:"net"`
-	// (--unshare-uts)
-	// create new uts namespace
-	UTS bool `json:"uts"`
-	// (--unshare-cgroup)
-	// create new cgroup namespace
-	CGroup bool `json:"cgroup"`
-}

helper/bwrap/config_test.go

@@ -1,257 +0,0 @@
-package bwrap_test
-
-import (
-	"log"
-	"os"
-	"slices"
-	"testing"
-
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
-)
-
-func TestConfig_Args(t *testing.T) {
-	seccomp.CPrintln = log.Println
-	t.Cleanup(func() { seccomp.CPrintln = nil })
-
-	testCases := []struct {
-		name string
-		conf *bwrap.Config
-		want []string
-	}{
-		{
-			"bind", (new(bwrap.Config)).
-				Bind("/etc", "/.fortify/etc").
-				Bind("/etc", "/.fortify/etc", true).
-				Bind("/run", "/.fortify/run", false, true).
-				Bind("/sys/devices", "/.fortify/sys/devices", true, true).
-				Bind("/dev/dri", "/.fortify/dev/dri", false, true, true).
-				Bind("/dev/dri", "/.fortify/dev/dri", true, true, true),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Bind("/etc", "/.fortify/etc")
-				"--ro-bind", "/etc", "/.fortify/etc",
-				// Bind("/etc", "/.fortify/etc", true)
-				"--ro-bind-try", "/etc", "/.fortify/etc",
-				// Bind("/run", "/.fortify/run", false, true)
-				"--bind", "/run", "/.fortify/run",
-				// Bind("/sys/devices", "/.fortify/sys/devices", true, true)
-				"--bind-try", "/sys/devices", "/.fortify/sys/devices",
-				// Bind("/dev/dri", "/.fortify/dev/dri", false, true, true)
-				"--dev-bind", "/dev/dri", "/.fortify/dev/dri",
-				// Bind("/dev/dri", "/.fortify/dev/dri", true, true, true)
-				"--dev-bind-try", "/dev/dri", "/.fortify/dev/dri",
-			},
-		},
-		{
-			"dir remount-ro proc dev mqueue", (new(bwrap.Config)).
-				Dir("/.fortify").
-				RemountRO("/home").
-				Procfs("/proc").
-				DevTmpfs("/dev").
-				Mqueue("/dev/mqueue"),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Dir("/.fortify")
-				"--dir", "/.fortify",
-				// RemountRO("/home")
-				"--remount-ro", "/home",
-				// Procfs("/proc")
-				"--proc", "/proc",
-				// DevTmpfs("/dev")
-				"--dev", "/dev",
-				// Mqueue("/dev/mqueue")
-				"--mqueue", "/dev/mqueue",
-			},
-		},
-		{
-			"tmpfs", (new(bwrap.Config)).
-				Tmpfs("/run/user", 8192).
-				Tmpfs("/run/dbus", 8192, 0755),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Tmpfs("/run/user", 8192)
-				"--size", "8192", "--tmpfs", "/run/user",
-				// Tmpfs("/run/dbus", 8192, 0755)
-				"--perms", "755", "--size", "8192", "--tmpfs", "/run/dbus",
-			},
-		},
-		{
-			"symlink", (new(bwrap.Config)).
-				Symlink("/.fortify/sbin/init", "/sbin/init").
-				Symlink("/.fortify/sbin/init", "/sbin/init", 0755),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Symlink("/.fortify/sbin/init", "/sbin/init")
-				"--symlink", "/.fortify/sbin/init", "/sbin/init",
-				// Symlink("/.fortify/sbin/init", "/sbin/init", 0755)
-				"--perms", "755", "--symlink", "/.fortify/sbin/init", "/sbin/init",
-			},
-		},
-		{
-			"overlayfs", (new(bwrap.Config)).
-				Overlay("/etc", "/etc").
-				Join("/.fortify/bin", "/bin", "/usr/bin", "/usr/local/bin").
-				Persist("/nix", "/data/data/org.chromium.Chromium/overlay/rwsrc", "/data/data/org.chromium.Chromium/workdir", "/data/app/org.chromium.Chromium/nix"),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Overlay("/etc", "/etc")
-				"--overlay-src", "/etc", "--tmp-overlay", "/etc",
-				// Join("/.fortify/bin", "/bin", "/usr/bin", "/usr/local/bin")
-				"--overlay-src", "/bin", "--overlay-src", "/usr/bin",
-				"--overlay-src", "/usr/local/bin", "--ro-overlay", "/.fortify/bin",
-				// Persist("/nix", "/data/data/org.chromium.Chromium/overlay/rwsrc", "/data/data/org.chromium.Chromium/workdir", "/data/app/org.chromium.Chromium/nix")
-				"--overlay-src", "/data/app/org.chromium.Chromium/nix",
-				"--overlay", "/data/data/org.chromium.Chromium/overlay/rwsrc", "/data/data/org.chromium.Chromium/workdir", "/nix",
-			},
-		},
-		{
-			"copy", (new(bwrap.Config)).
-				WriteFile("/.fortify/version", make([]byte, 8)).
-				CopyBind("/etc/group", make([]byte, 8)).
-				CopyBind("/etc/passwd", make([]byte, 8), true),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Write("/.fortify/version", make([]byte, 8))
-				"--file", "3", "/.fortify/version",
-				// CopyBind("/etc/group", make([]byte, 8))
-				"--ro-bind-data", "4", "/etc/group",
-				// CopyBind("/etc/passwd", make([]byte, 8), true)
-				"--bind-data", "5", "/etc/passwd",
-			},
-		},
-		{
-			"unshare", &bwrap.Config{Unshare: &bwrap.UnshareConfig{
-				User:   false,
-				IPC:    false,
-				PID:    false,
-				Net:    false,
-				UTS:    false,
-				CGroup: false,
-			}},
-			[]string{"--disable-userns", "--assert-userns-disabled"},
-		},
-		{
-			"uid gid sync", (new(bwrap.Config)).
-				SetUID(1971).
-				SetGID(100),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// SetUID(1971)
-				"--uid", "1971",
-				// SetGID(100)
-				"--gid", "100",
-			},
-		},
-		{
-			"hostname chdir setenv unsetenv lockfile chmod syscall", &bwrap.Config{
-				Hostname: "fortify",
-				Chdir:    "/.fortify",
-				SetEnv:   map[string]string{"FORTIFY_INIT": "/.fortify/sbin/init"},
-				UnsetEnv: []string{"HOME", "HOST"},
-				LockFile: []string{"/.fortify/lock"},
-				Syscall:  new(bwrap.SyscallPolicy),
-				Chmod:    map[string]os.FileMode{"/.fortify/sbin/init": 0755},
-			},
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				// Hostname: "fortify"
-				"--hostname", "fortify",
-				// Chdir: "/.fortify"
-				"--chdir", "/.fortify",
-				// UnsetEnv: []string{"HOME", "HOST"}
-				"--unsetenv", "HOME",
-				"--unsetenv", "HOST",
-				// LockFile: []string{"/.fortify/lock"},
-				"--lock-file", "/.fortify/lock",
-				// SetEnv: map[string]string{"FORTIFY_INIT": "/.fortify/sbin/init"}
-				"--setenv", "FORTIFY_INIT", "/.fortify/sbin/init",
-				// Syscall: new(bwrap.SyscallPolicy),
-				"--seccomp", "3",
-				// Chmod: map[string]os.FileMode{"/.fortify/sbin/init": 0755}
-				"--chmod", "755", "/.fortify/sbin/init",
-			},
-		},
-
-		{
-			"xdg-dbus-proxy constraint sample", (&bwrap.Config{Clearenv: true, DieWithParent: true}).
-				Symlink("usr/bin", "/bin").
-				Symlink("var/home", "/home").
-				Symlink("usr/lib", "/lib").
-				Symlink("usr/lib64", "/lib64").
-				Symlink("run/media", "/media").
-				Symlink("var/mnt", "/mnt").
-				Symlink("var/opt", "/opt").
-				Symlink("sysroot/ostree", "/ostree").
-				Symlink("var/roothome", "/root").
-				Symlink("usr/sbin", "/sbin").
-				Symlink("var/srv", "/srv").
-				Bind("/run", "/run", false, true).
-				Bind("/tmp", "/tmp", false, true).
-				Bind("/var", "/var", false, true).
-				Bind("/run/user/1971/.dbus-proxy/", "/run/user/1971/.dbus-proxy/", false, true).
-				Bind("/boot", "/boot").
-				Bind("/dev", "/dev").
-				Bind("/proc", "/proc").
-				Bind("/sys", "/sys").
-				Bind("/sysroot", "/sysroot").
-				Bind("/usr", "/usr").
-				Bind("/etc", "/etc"),
-			[]string{
-				"--unshare-all", "--unshare-user",
-				"--disable-userns", "--assert-userns-disabled",
-				"--clearenv", "--die-with-parent",
-				"--symlink", "usr/bin", "/bin",
-				"--symlink", "var/home", "/home",
-				"--symlink", "usr/lib", "/lib",
-				"--symlink", "usr/lib64", "/lib64",
-				"--symlink", "run/media", "/media",
-				"--symlink", "var/mnt", "/mnt",
-				"--symlink", "var/opt", "/opt",
-				"--symlink", "sysroot/ostree", "/ostree",
-				"--symlink", "var/roothome", "/root",
-				"--symlink", "usr/sbin", "/sbin",
-				"--symlink", "var/srv", "/srv",
-				"--bind", "/run", "/run",
-				"--bind", "/tmp", "/tmp",
-				"--bind", "/var", "/var",
-				"--bind", "/run/user/1971/.dbus-proxy/", "/run/user/1971/.dbus-proxy/",
-				"--ro-bind", "/boot", "/boot",
-				"--ro-bind", "/dev", "/dev",
-				"--ro-bind", "/proc", "/proc",
-				"--ro-bind", "/sys", "/sys",
-				"--ro-bind", "/sysroot", "/sysroot",
-				"--ro-bind", "/usr", "/usr",
-				"--ro-bind", "/etc", "/etc",
-			},
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			if got := tc.conf.Args(nil, new(proc.ExtraFilesPre), new([]proc.File)); !slices.Equal(got, tc.want) {
-				t.Errorf("Args() = %#v, want %#v", got, tc.want)
-			}
-		})
-	}
-
-	// test persist validation
-	t.Run("invalid persist", func(t *testing.T) {
-		defer func() {
-			wantPanic := "persist called without required paths"
-			if r := recover(); r != wantPanic {
-				t.Errorf("Persist() panic = %v; wantPanic %v", r, wantPanic)
-			}
-		}()
-		(new(bwrap.Config)).Persist("/run", "", "")
-	})
-}

helper/bwrap/seccomp.go

@@ -1,85 +0,0 @@
-package bwrap
-
-import (
-	"fmt"
-	"strconv"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
-)
-
-type SyscallPolicy struct {
-	// disable fortify extensions
-	Compat bool `json:"compat"`
-	// deny development syscalls
-	DenyDevel bool `json:"deny_devel"`
-	// deny multiarch/emulation syscalls
-	Multiarch bool `json:"multiarch"`
-	// allow PER_LINUX32
-	Linux32 bool `json:"linux32"`
-	// allow AF_CAN
-	Can bool `json:"can"`
-	// allow AF_BLUETOOTH
-	Bluetooth bool `json:"bluetooth"`
-}
-
-func (c *Config) seccompArgs() FDBuilder {
-	// explicitly disable syscall filter
-	if c.Syscall == nil {
-		// nil File skips builder
-		return new(seccompBuilder)
-	}
-
-	var (
-		opts    seccomp.SyscallOpts
-		optd    []string
-		optCond = [...]struct {
-			v bool
-			o seccomp.SyscallOpts
-			d string
-		}{
-			{!c.Syscall.Compat, seccomp.FlagExt, "fortify"},
-			{!c.UserNS, seccomp.FlagDenyNS, "denyns"},
-			{c.NewSession, seccomp.FlagDenyTTY, "denytty"},
-			{c.Syscall.DenyDevel, seccomp.FlagDenyDevel, "denydevel"},
-			{c.Syscall.Multiarch, seccomp.FlagMultiarch, "multiarch"},
-			{c.Syscall.Linux32, seccomp.FlagLinux32, "linux32"},
-			{c.Syscall.Can, seccomp.FlagCan, "can"},
-			{c.Syscall.Bluetooth, seccomp.FlagBluetooth, "bluetooth"},
-		}
-	)
-	if seccomp.CPrintln != nil {
-		optd = make([]string, 1, len(optCond)+1)
-		optd[0] = "common"
-	}
-	for _, opt := range optCond {
-		if opt.v {
-			opts |= opt.o
-			if seccomp.CPrintln != nil {
-				optd = append(optd, opt.d)
-			}
-		}
-	}
-	if seccomp.CPrintln != nil {
-		seccomp.CPrintln(fmt.Sprintf("seccomp flags: %s", optd))
-	}
-
-	return &seccompBuilder{seccomp.NewFile(opts)}
-}
-
-type seccompBuilder struct{ proc.File }
-
-func (s *seccompBuilder) Len() int {
-	if s == nil || s.File == nil {
-		return 0
-	}
-	return 2
-}
-
-func (s *seccompBuilder) Append(args *[]string) {
-	if s == nil || s.File == nil {
-		return
-	}
-
-	*args = append(*args, Seccomp.String(), strconv.Itoa(int(s.Fd())))
-}

helper/bwrap/sequential.go

@@ -1,273 +0,0 @@
-package bwrap
-
-import (
-	"encoding/gob"
-	"fmt"
-	"io"
-	"os"
-	"strconv"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-)
-
-func init() {
-	gob.Register(new(PermConfig[SymlinkConfig]))
-	gob.Register(new(PermConfig[*TmpfsConfig]))
-	gob.Register(new(OverlayConfig))
-	gob.Register(new(DataConfig))
-}
-
-type PositionalArg int
-
-func (p PositionalArg) String() string { return positionalArgs[p] }
-
-const (
-	Tmpfs PositionalArg = iota
-	Symlink
-
-	Bind
-	BindTry
-	DevBind
-	DevBindTry
-	ROBind
-	ROBindTry
-
-	Chmod
-	Dir
-	RemountRO
-	Procfs
-	DevTmpfs
-	Mqueue
-
-	Perms
-	Size
-
-	OverlaySrc
-	Overlay
-	TmpOverlay
-	ROOverlay
-
-	SyncFd
-	Seccomp
-
-	File
-	BindData
-	ROBindData
-)
-
-var positionalArgs = [...]string{
-	Tmpfs:   "--tmpfs",
-	Symlink: "--symlink",
-
-	Bind:       "--bind",
-	BindTry:    "--bind-try",
-	DevBind:    "--dev-bind",
-	DevBindTry: "--dev-bind-try",
-	ROBind:     "--ro-bind",
-	ROBindTry:  "--ro-bind-try",
-
-	Chmod:     "--chmod",
-	Dir:       "--dir",
-	RemountRO: "--remount-ro",
-	Procfs:    "--proc",
-	DevTmpfs:  "--dev",
-	Mqueue:    "--mqueue",
-
-	Perms: "--perms",
-	Size:  "--size",
-
-	OverlaySrc: "--overlay-src",
-	Overlay:    "--overlay",
-	TmpOverlay: "--tmp-overlay",
-	ROOverlay:  "--ro-overlay",
-
-	SyncFd:  "--sync-fd",
-	Seccomp: "--seccomp",
-
-	File:       "--file",
-	BindData:   "--bind-data",
-	ROBindData: "--ro-bind-data",
-}
-
-type PermConfig[T FSBuilder] struct {
-	// set permissions of next argument
-	// (--perms OCTAL)
-	Mode *os.FileMode `json:"mode,omitempty"`
-	// path to get the new permission
-	// (--bind-data, --file, etc.)
-	Inner T `json:"path"`
-}
-
-func (p *PermConfig[T]) Path() string { return p.Inner.Path() }
-
-func (p *PermConfig[T]) Len() int {
-	if p.Mode != nil {
-		return p.Inner.Len() + 2
-	} else {
-		return p.Inner.Len()
-	}
-}
-
-func (p *PermConfig[T]) Append(args *[]string) {
-	if p.Mode != nil {
-		*args = append(*args, Perms.String(), strconv.FormatInt(int64(*p.Mode), 8))
-	}
-	p.Inner.Append(args)
-}
-
-type TmpfsConfig struct {
-	// set size of tmpfs
-	// (--size BYTES)
-	Size int `json:"size,omitempty"`
-	// mount point of new tmpfs
-	// (--tmpfs DEST)
-	Dir string `json:"dir"`
-}
-
-func (t *TmpfsConfig) Path() string { return t.Dir }
-
-func (t *TmpfsConfig) Len() int {
-	if t.Size > 0 {
-		return 4
-	} else {
-		return 2
-	}
-}
-
-func (t *TmpfsConfig) Append(args *[]string) {
-	if t.Size > 0 {
-		*args = append(*args, Size.String(), strconv.Itoa(t.Size))
-	}
-	*args = append(*args, Tmpfs.String(), t.Dir)
-}
-
-type OverlayConfig struct {
-	/*
-		read files from SRC in the following overlay
-		(--overlay-src SRC)
-	*/
-	Src []string `json:"src,omitempty"`
-
-	/*
-		mount overlayfs on DEST, with RWSRC as the host path for writes and
-		WORKDIR an empty directory on the same filesystem as RWSRC
-		(--overlay RWSRC WORKDIR DEST)
-
-		if nil, mount overlayfs on DEST, with writes going to an invisible tmpfs
-		(--tmp-overlay DEST)
-
-		if either strings are empty, mount overlayfs read-only on DEST
-		(--ro-overlay DEST)
-	*/
-	Persist *[2]string `json:"persist,omitempty"`
-
-	/*
-		--overlay RWSRC WORKDIR DEST
-
-		--tmp-overlay DEST
-
-		--ro-overlay DEST
-	*/
-	Dest string `json:"dest"`
-}
-
-func (o *OverlayConfig) Path() string { return o.Dest }
-
-func (o *OverlayConfig) Len() int {
-	// (--tmp-overlay DEST) or (--ro-overlay DEST)
-	p := 2
-	// (--overlay RWSRC WORKDIR DEST)
-	if o.Persist != nil && o.Persist[0] != "" && o.Persist[1] != "" {
-		p = 4
-	}
-
-	return p + len(o.Src)*2
-}
-
-func (o *OverlayConfig) Append(args *[]string) {
-	// --overlay-src SRC
-	for _, src := range o.Src {
-		*args = append(*args, OverlaySrc.String(), src)
-	}
-
-	if o.Persist != nil {
-		if o.Persist[0] != "" && o.Persist[1] != "" {
-			// --overlay RWSRC WORKDIR
-			*args = append(*args, Overlay.String(), o.Persist[0], o.Persist[1])
-		} else {
-			// --ro-overlay
-			*args = append(*args, ROOverlay.String())
-		}
-	} else {
-		// --tmp-overlay
-		*args = append(*args, TmpOverlay.String())
-	}
-
-	// DEST
-	*args = append(*args, o.Dest)
-}
-
-type SymlinkConfig [2]string
-
-func (s SymlinkConfig) Path() string          { return s[1] }
-func (s SymlinkConfig) Len() int              { return 3 }
-func (s SymlinkConfig) Append(args *[]string) { *args = append(*args, Symlink.String(), s[0], s[1]) }
-
-type ChmodConfig map[string]os.FileMode
-
-func (c ChmodConfig) Len() int { return len(c) }
-func (c ChmodConfig) Append(args *[]string) {
-	for path, mode := range c {
-		*args = append(*args, Chmod.String(), strconv.FormatInt(int64(mode), 8), path)
-	}
-}
-
-const (
-	DataWrite = iota
-	DataBind
-	DataROBind
-)
-
-type DataConfig struct {
-	Dest string `json:"dest"`
-	Data []byte `json:"data,omitempty"`
-	Type int    `json:"type"`
-	proc.File
-}
-
-func (d *DataConfig) Path() string { return d.Dest }
-func (d *DataConfig) Len() int {
-	if d == nil || d.Data == nil {
-		return 0
-	}
-	return 3
-}
-func (d *DataConfig) Init(fd uintptr, v **os.File) uintptr {
-	if d.File != nil {
-		panic("file initialised twice")
-	}
-	d.File = proc.NewWriterTo(d)
-	return d.File.Init(fd, v)
-}
-func (d *DataConfig) WriteTo(w io.Writer) (int64, error) {
-	n, err := w.Write(d.Data)
-	return int64(n), err
-}
-func (d *DataConfig) Append(args *[]string) {
-	if d == nil || d.Data == nil {
-		return
-	}
-	var a PositionalArg
-	switch d.Type {
-	case DataWrite:
-		a = File
-	case DataBind:
-		a = BindData
-	case DataROBind:
-		a = ROBindData
-	default:
-		panic(fmt.Sprintf("invalid type %d", a))
-	}
-
-	*args = append(*args, a.String(), strconv.Itoa(int(d.Fd())), d.Dest)
-}

helper/bwrap/static.go

@@ -1,249 +0,0 @@
-package bwrap
-
-import (
-	"slices"
-	"strconv"
-)
-
-/*
-	static boolean args
-*/
-
-type BoolArg int
-
-func (b BoolArg) Unwrap() []string {
-	return boolArgs[b]
-}
-
-const (
-	UnshareAll BoolArg = iota
-	UnshareUser
-	UnshareIPC
-	UnsharePID
-	UnshareNet
-	UnshareUTS
-	UnshareCGroup
-	ShareNet
-
-	UserNS
-	Clearenv
-
-	NewSession
-	DieWithParent
-	AsInit
-)
-
-var boolArgs = [...][]string{
-	UnshareAll:    {"--unshare-all", "--unshare-user"},
-	UnshareUser:   {"--unshare-user"},
-	UnshareIPC:    {"--unshare-ipc"},
-	UnsharePID:    {"--unshare-pid"},
-	UnshareNet:    {"--unshare-net"},
-	UnshareUTS:    {"--unshare-uts"},
-	UnshareCGroup: {"--unshare-cgroup"},
-	ShareNet:      {"--share-net"},
-
-	UserNS:   {"--disable-userns", "--assert-userns-disabled"},
-	Clearenv: {"--clearenv"},
-
-	NewSession:    {"--new-session"},
-	DieWithParent: {"--die-with-parent"},
-	AsInit:        {"--as-pid-1"},
-}
-
-func (c *Config) boolArgs() Builder {
-	b := boolArg{
-		UserNS:   !c.UserNS,
-		Clearenv: c.Clearenv,
-
-		NewSession:    c.NewSession,
-		DieWithParent: c.DieWithParent,
-		AsInit:        c.AsInit,
-	}
-
-	if c.Unshare == nil {
-		b[UnshareAll] = true
-		b[ShareNet] = c.Net
-	} else {
-		b[UnshareUser] = c.Unshare.User
-		b[UnshareIPC] = c.Unshare.IPC
-		b[UnsharePID] = c.Unshare.PID
-		b[UnshareNet] = c.Unshare.Net
-		b[UnshareUTS] = c.Unshare.UTS
-		b[UnshareCGroup] = c.Unshare.CGroup
-	}
-
-	return &b
-}
-
-type boolArg [len(boolArgs)]bool
-
-func (b *boolArg) Len() (l int) {
-	for i, v := range b {
-		if v {
-			l += len(boolArgs[i])
-		}
-	}
-	return
-}
-
-func (b *boolArg) Append(args *[]string) {
-	for i, v := range b {
-		if v {
-			*args = append(*args, BoolArg(i).Unwrap()...)
-		}
-	}
-}
-
-/*
-	static integer args
-*/
-
-type IntArg int
-
-func (i IntArg) Unwrap() string {
-	return intArgs[i]
-}
-
-const (
-	UID IntArg = iota
-	GID
-)
-
-var intArgs = [...]string{
-	UID: "--uid",
-	GID: "--gid",
-}
-
-func (c *Config) intArgs() Builder {
-	return &intArg{
-		UID: c.UID,
-		GID: c.GID,
-	}
-}
-
-type intArg [len(intArgs)]*int
-
-func (n *intArg) Len() (l int) {
-	for _, v := range n {
-		if v != nil {
-			l += 2
-		}
-	}
-	return
-}
-
-func (n *intArg) Append(args *[]string) {
-	for i, v := range n {
-		if v != nil {
-			*args = append(*args, IntArg(i).Unwrap(), strconv.Itoa(*v))
-		}
-	}
-}
-
-/*
-	static string args
-*/
-
-type StringArg int
-
-func (s StringArg) Unwrap() string {
-	return stringArgs[s]
-}
-
-const (
-	Hostname StringArg = iota
-	Chdir
-	UnsetEnv
-	LockFile
-)
-
-var stringArgs = [...]string{
-	Hostname: "--hostname",
-	Chdir:    "--chdir",
-	UnsetEnv: "--unsetenv",
-	LockFile: "--lock-file",
-}
-
-func (c *Config) stringArgs() Builder {
-	n := stringArg{
-		UnsetEnv: c.UnsetEnv,
-		LockFile: c.LockFile,
-	}
-
-	if c.Hostname != "" {
-		n[Hostname] = []string{c.Hostname}
-	}
-	if c.Chdir != "" {
-		n[Chdir] = []string{c.Chdir}
-	}
-
-	return &n
-}
-
-type stringArg [len(stringArgs)][]string
-
-func (s *stringArg) Len() (l int) {
-	for _, arg := range s {
-		l += len(arg) * 2
-	}
-	return
-}
-
-func (s *stringArg) Append(args *[]string) {
-	for i, arg := range s {
-		for _, v := range arg {
-			*args = append(*args, StringArg(i).Unwrap(), v)
-		}
-	}
-}
-
-/*
-	static pair args
-*/
-
-type PairArg int
-
-func (p PairArg) Unwrap() string {
-	return pairArgs[p]
-}
-
-const (
-	SetEnv PairArg = iota
-)
-
-var pairArgs = [...]string{
-	SetEnv: "--setenv",
-}
-
-func (c *Config) pairArgs() Builder {
-	var n pairArg
-	n[SetEnv] = make([][2]string, len(c.SetEnv))
-	keys := make([]string, 0, len(c.SetEnv))
-	for k := range c.SetEnv {
-		keys = append(keys, k)
-	}
-	slices.Sort(keys)
-	for i, k := range keys {
-		n[SetEnv][i] = [2]string{k, c.SetEnv[k]}
-	}
-
-	return &n
-}
-
-type pairArg [len(pairArgs)][][2]string
-
-func (p *pairArg) Len() (l int) {
-	for _, v := range p {
-		l += len(v) * 3
-	}
-	return
-}
-
-func (p *pairArg) Append(args *[]string) {
-	for i, arg := range p {
-		for _, v := range arg {
-			*args = append(*args, PairArg(i).Unwrap(), v[0], v[1])
-		}
-	}
-}

helper/bwrap/trivial.go

@@ -1,52 +0,0 @@
-package bwrap
-
-import (
-	"context"
-	"encoding/gob"
-	"os"
-	"strconv"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-)
-
-func init() {
-	gob.Register(new(pairF))
-	gob.Register(new(stringF))
-}
-
-type pairF [3]string
-
-func (p *pairF) Path() string          { return p[2] }
-func (p *pairF) Len() int              { return len(p) }
-func (p *pairF) Append(args *[]string) { *args = append(*args, p[0], p[1], p[2]) }
-
-type stringF [2]string
-
-func (s stringF) Path() string          { return s[1] }
-func (s stringF) Len() int              { return len(s) /* compiler replaces this with 2 */ }
-func (s stringF) Append(args *[]string) { *args = append(*args, s[0], s[1]) }
-
-func newFile(name string, f *os.File) FDBuilder { return &fileF{name: name, file: f} }
-
-type fileF struct {
-	name string
-	file *os.File
-	proc.BaseFile
-}
-
-func (f *fileF) ErrCount() int                                  { return 0 }
-func (f *fileF) Fulfill(_ context.Context, _ func(error)) error { f.Set(f.file); return nil }
-
-func (f *fileF) Len() int {
-	if f.file == nil {
-		return 0
-	}
-	return 2
-}
-
-func (f *fileF) Append(args *[]string) {
-	if f.file == nil {
-		return
-	}
-	*args = append(*args, f.name, strconv.Itoa(int(f.Fd())))
-}

helper/bwrap_test.go

@@ -1,108 +0,0 @@
-package helper_test
-
-import (
-	"context"
-	"errors"
-	"os"
-	"strings"
-	"testing"
-	"time"
-
-	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-)
-
-func TestBwrap(t *testing.T) {
-	sc := &bwrap.Config{
-		Net:           true,
-		Hostname:      "localhost",
-		Chdir:         "/nonexistent",
-		Clearenv:      true,
-		NewSession:    true,
-		DieWithParent: true,
-		AsInit:        true,
-	}
-
-	t.Run("nonexistent bwrap name", func(t *testing.T) {
-		bubblewrapName := helper.BubblewrapName
-		helper.BubblewrapName = "/nonexistent"
-		t.Cleanup(func() {
-			helper.BubblewrapName = bubblewrapName
-		})
-
-		h := helper.MustNewBwrap(
-			sc, "fortify", false,
-			argsWt, argF,
-			nil, nil,
-		)
-
-		if err := h.Start(context.Background(), false); !errors.Is(err, os.ErrNotExist) {
-			t.Errorf("Start: error = %v, wantErr %v",
-				err, os.ErrNotExist)
-		}
-	})
-
-	t.Run("valid new helper nil check", func(t *testing.T) {
-		if got := helper.MustNewBwrap(
-			sc, "fortify", false,
-			argsWt, argF,
-			nil, nil,
-		); got == nil {
-			t.Errorf("MustNewBwrap(%#v, %#v, %#v) got nil",
-				sc, argsWt, "fortify")
-			return
-		}
-	})
-
-	t.Run("invalid bwrap config new helper panic", func(t *testing.T) {
-		defer func() {
-			wantPanic := "argument contains null character"
-			if r := recover(); r != wantPanic {
-				t.Errorf("MustNewBwrap: panic = %q, want %q",
-					r, wantPanic)
-			}
-		}()
-
-		helper.MustNewBwrap(
-			&bwrap.Config{Hostname: "\x00"}, "fortify", false,
-			nil, argF,
-			nil, nil,
-		)
-	})
-
-	t.Run("start without pipes", func(t *testing.T) {
-		helper.InternalReplaceExecCommand(t)
-
-		h := helper.MustNewBwrap(
-			sc, "crash-test-dummy", false,
-			nil, argFChecked,
-			nil, nil,
-		)
-
-		stdout, stderr := new(strings.Builder), new(strings.Builder)
-		h.Stdout(stdout).Stderr(stderr)
-
-		c, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-		defer cancel()
-
-		if err := h.Start(c, false); err != nil {
-			t.Errorf("Start: error = %v",
-				err)
-			return
-		}
-
-		if err := h.Wait(); err != nil {
-			t.Errorf("Wait() err = %v stderr = %s",
-				err, stderr)
-		}
-	})
-
-	t.Run("implementation compliance", func(t *testing.T) {
-		testHelper(t, func() helper.Helper {
-			return helper.MustNewBwrap(
-				sc, "crash-test-dummy", false,
-				argsWt, argF, nil, nil,
-			)
-		})
-	})
-}

helper/cmd.go

@@ -0,0 +1,84 @@
+package helper
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"slices"
+	"sync"
+	"syscall"
+
+	"git.gensokyo.uk/security/fortify/helper/proc"
+)
+
+// NewDirect initialises a new direct Helper instance with wt as the null-terminated argument writer.
+// Function argF returns an array of arguments passed directly to the child process.
+func NewDirect(
+	ctx context.Context,
+	name string,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
+	cmdF func(cmd *exec.Cmd),
+	extraFiles []*os.File,
+) Helper {
+	d, args := newHelperCmd(ctx, name, wt, stat, argF, extraFiles)
+	d.Args = append(d.Args, args...)
+	if cmdF != nil {
+		cmdF(d.Cmd)
+	}
+	return d
+}
+
+func newHelperCmd(
+	ctx context.Context,
+	name string,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
+	extraFiles []*os.File,
+) (cmd *helperCmd, args []string) {
+	cmd = new(helperCmd)
+	cmd.helperFiles, args = newHelperFiles(ctx, wt, stat, argF, extraFiles)
+	cmd.Cmd = exec.CommandContext(ctx, name)
+	cmd.Cmd.Cancel = func() error { return cmd.Process.Signal(syscall.SIGTERM) }
+	cmd.WaitDelay = WaitDelay
+	return
+}
+
+// helperCmd provides a [exec.Cmd] wrapper around helper ipc.
+type helperCmd struct {
+	mu sync.RWMutex
+	*helperFiles
+	*exec.Cmd
+}
+
+func (h *helperCmd) Start() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	// Check for doubled Start calls before we defer failure cleanup. If the prior
+	// call to Start succeeded, we don't want to spuriously close its pipes.
+	if h.Cmd != nil && h.Cmd.Process != nil {
+		return errors.New("helper: already started")
+	}
+
+	h.Env = slices.Grow(h.Env, 2)
+	if h.useArgsFd {
+		h.Env = append(h.Env, FortifyHelper+"=1")
+	} else {
+		h.Env = append(h.Env, FortifyHelper+"=0")
+	}
+	if h.useStatFd {
+		h.Env = append(h.Env, FortifyStatus+"=1")
+
+		// stat is populated on fulfill
+		h.Cancel = func() error { return h.stat.Close() }
+	} else {
+		h.Env = append(h.Env, FortifyStatus+"=0")
+	}
+
+	return proc.Fulfill(h.helperFiles.ctx, &h.ExtraFiles, h.Cmd.Start, h.files, h.extraFiles)
+}

helper/cmd_test.go

@@ -0,0 +1,39 @@
+package helper_test
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/helper"
+)
+
+func TestCmd(t *testing.T) {
+	t.Run("start non-existent helper path", func(t *testing.T) {
+		h := helper.NewDirect(context.Background(), "/proc/nonexistent", argsWt, false, argF, nil, nil)
+
+		if err := h.Start(); !errors.Is(err, os.ErrNotExist) {
+			t.Errorf("Start: error = %v, wantErr %v",
+				err, os.ErrNotExist)
+		}
+	})
+
+	t.Run("valid new helper nil check", func(t *testing.T) {
+		if got := helper.NewDirect(context.TODO(), "fortify", argsWt, false, argF, nil, nil); got == nil {
+			t.Errorf("NewDirect(%q, %q) got nil",
+				argsWt, "fortify")
+			return
+		}
+	})
+
+	t.Run("implementation compliance", func(t *testing.T) {
+		testHelper(t, func(ctx context.Context, setOutput func(stdoutP, stderrP *io.Writer), stat bool) helper.Helper {
+			return helper.NewDirect(ctx, os.Args[0], argsWt, stat, argF, func(cmd *exec.Cmd) {
+				setOutput(&cmd.Stdout, &cmd.Stderr)
+			}, nil)
+		})
+	})
+}

helper/container.go

@@ -0,0 +1,76 @@
+package helper
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"slices"
+	"sync"
+
+	"git.gensokyo.uk/security/fortify/helper/proc"
+	"git.gensokyo.uk/security/fortify/sandbox"
+)
+
+// New initialises a Helper instance with wt as the null-terminated argument writer.
+func New(
+	ctx context.Context,
+	name string,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
+	cmdF func(container *sandbox.Container),
+	extraFiles []*os.File,
+) Helper {
+	var args []string
+	h := new(helperContainer)
+	h.helperFiles, args = newHelperFiles(ctx, wt, stat, argF, extraFiles)
+	h.Container = sandbox.New(ctx, name, args...)
+	h.WaitDelay = WaitDelay
+	if cmdF != nil {
+		cmdF(h.Container)
+	}
+	return h
+}
+
+// helperContainer provides a [sandbox.Container] wrapper around helper ipc.
+type helperContainer struct {
+	started bool
+
+	mu sync.Mutex
+	*helperFiles
+	*sandbox.Container
+}
+
+func (h *helperContainer) Start() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if h.started {
+		return errors.New("helper: already started")
+	}
+	h.started = true
+
+	h.Env = slices.Grow(h.Env, 2)
+	if h.useArgsFd {
+		h.Env = append(h.Env, FortifyHelper+"=1")
+	} else {
+		h.Env = append(h.Env, FortifyHelper+"=0")
+	}
+	if h.useStatFd {
+		h.Env = append(h.Env, FortifyStatus+"=1")
+
+		// stat is populated on fulfill
+		h.Cancel = func(*exec.Cmd) error { return h.stat.Close() }
+	} else {
+		h.Env = append(h.Env, FortifyStatus+"=0")
+	}
+
+	return proc.Fulfill(h.helperFiles.ctx, &h.ExtraFiles, func() error {
+		if err := h.Container.Start(); err != nil {
+			return err
+		}
+		return h.Container.Serve()
+	}, h.files, h.extraFiles)
+}

helper/container_test.go

@@ -0,0 +1,57 @@
+package helper_test
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/helper"
+	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/sandbox"
+)
+
+func TestContainer(t *testing.T) {
+	t.Run("start empty container", func(t *testing.T) {
+		h := helper.New(context.Background(), "/nonexistent", argsWt, false, argF, nil, nil)
+
+		wantErr := "sandbox: starting an empty container"
+		if err := h.Start(); err == nil || err.Error() != wantErr {
+			t.Errorf("Start: error = %v, wantErr %q",
+				err, wantErr)
+		}
+	})
+
+	t.Run("valid new helper nil check", func(t *testing.T) {
+		if got := helper.New(context.TODO(), "fortify", argsWt, false, argF, nil, nil); got == nil {
+			t.Errorf("New(%q, %q) got nil",
+				argsWt, "fortify")
+			return
+		}
+	})
+
+	t.Run("implementation compliance", func(t *testing.T) {
+		testHelper(t, func(ctx context.Context, setOutput func(stdoutP, stderrP *io.Writer), stat bool) helper.Helper {
+			return helper.New(ctx, os.Args[0], argsWt, stat, argF, func(container *sandbox.Container) {
+				setOutput(&container.Stdout, &container.Stderr)
+				container.CommandContext = func(ctx context.Context) (cmd *exec.Cmd) {
+					return exec.CommandContext(ctx, os.Args[0], "-test.v",
+						"-test.run=TestHelperInit", "--", "init")
+				}
+				container.Bind("/", "/", 0)
+				container.Proc("/proc")
+				container.Dev("/dev")
+			}, nil)
+		})
+	})
+}
+
+func TestHelperInit(t *testing.T) {
+	if len(os.Args) != 5 || os.Args[4] != "init" {
+		return
+	}
+	sandbox.SetOutput(fmsg.Output{})
+	sandbox.Init(fmsg.Prepare, func(bool) { internal.InstallFmsg(false) })
+}

helper/direct.go

@@ -1,40 +0,0 @@
-package helper
-
-import (
-	"context"
-	"errors"
-	"io"
-	"sync"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-)
-
-// direct wraps *exec.Cmd and manages status and args fd.
-// Args is always 3 and status if set is always 4.
-type direct struct {
-	lock sync.RWMutex
-	*helperCmd
-}
-
-func (h *direct) Start(ctx context.Context, stat bool) error {
-	h.lock.Lock()
-	defer h.lock.Unlock()
-
-	// Check for doubled Start calls before we defer failure cleanup. If the prior
-	// call to Start succeeded, we don't want to spuriously close its pipes.
-	if h.Cmd != nil && h.Cmd.Process != nil {
-		return errors.New("exec: already started")
-	}
-
-	args := h.finalise(ctx, stat)
-	h.Cmd.Args = append(h.Cmd.Args, args...)
-	return proc.Fulfill(ctx, h.Cmd, h.files, h.extraFiles)
-}
-
-// New initialises a new direct Helper instance with wt as the null-terminated argument writer.
-// Function argF returns an array of arguments passed directly to the child process.
-func New(wt io.WriterTo, name string, argF func(argsFd, statFd int) []string) Helper {
-	d := new(direct)
-	d.helperCmd = newHelperCmd(d, name, wt, argF, nil)
-	return d
-}

helper/direct_test.go

@@ -1,33 +0,0 @@
-package helper_test
-
-import (
-	"context"
-	"errors"
-	"os"
-	"testing"
-
-	"git.gensokyo.uk/security/fortify/helper"
-)
-
-func TestDirect(t *testing.T) {
-	t.Run("start non-existent helper path", func(t *testing.T) {
-		h := helper.New(argsWt, "/nonexistent", argF)
-
-		if err := h.Start(context.Background(), false); !errors.Is(err, os.ErrNotExist) {
-			t.Errorf("Start: error = %v, wantErr %v",
-				err, os.ErrNotExist)
-		}
-	})
-
-	t.Run("valid new helper nil check", func(t *testing.T) {
-		if got := helper.New(argsWt, "fortify", argF); got == nil {
-			t.Errorf("New(%q, %q) got nil",
-				argsWt, "fortify")
-			return
-		}
-	})
-
-	t.Run("implementation compliance", func(t *testing.T) {
-		testHelper(t, func() helper.Helper { return helper.New(argsWt, "crash-test-dummy", argF) })
-	})
-}

helper/helper.go

@@ -1,4 +1,4 @@
-// Package helper runs external helpers with optional sandboxing and manages their status/args pipes.
+// Package helper runs external helpers with optional sandboxing.
 package helper
 
 import (
@@ -6,17 +6,12 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"os/exec"
-	"slices"
-	"syscall"
 	"time"
 
 	"git.gensokyo.uk/security/fortify/helper/proc"
 )
 
-var (
-	WaitDelay = 2 * time.Second
-)
+var WaitDelay = 2 * time.Second
 
 const (
 	// FortifyHelper is set to 1 when args fd is enabled and 0 otherwise.
@@ -26,62 +21,56 @@ const (
 )
 
 type Helper interface {
-	// Stdin sets the standard input of Helper.
-	Stdin(r io.Reader) Helper
-	// Stdout sets the standard output of Helper.
-	Stdout(w io.Writer) Helper
-	// Stderr sets the standard error of Helper.
-	Stderr(w io.Writer) Helper
-	// SetEnv sets the environment of Helper.
-	SetEnv(env []string) Helper
-
 	// Start starts the helper process.
-	// A status pipe is passed to the helper if stat is true.
-	Start(ctx context.Context, stat bool) error
-	// Wait blocks until Helper exits and releases all its resources.
+	Start() error
+	// Wait blocks until Helper exits.
 	Wait() error
 
 	fmt.Stringer
 }
 
-func newHelperCmd(
-	h Helper, name string,
-	wt io.WriterTo, argF func(argsFd, statFd int) []string,
+func newHelperFiles(
+	ctx context.Context,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
 	extraFiles []*os.File,
-) (cmd *helperCmd) {
-	cmd = new(helperCmd)
+) (hl *helperFiles, args []string) {
+	hl = new(helperFiles)
+	hl.ctx = ctx
+	hl.useArgsFd = wt != nil
+	hl.useStatFd = stat
 
-	cmd.r = h
-	cmd.name = name
-
-	cmd.extraFiles = new(proc.ExtraFilesPre)
+	hl.extraFiles = new(proc.ExtraFilesPre)
 	for _, f := range extraFiles {
-		_, v := cmd.extraFiles.Append()
+		_, v := hl.extraFiles.Append()
 		*v = f
 	}
 
 	argsFd := -1
-	if wt != nil {
+	if hl.useArgsFd {
 		f := proc.NewWriterTo(wt)
-		argsFd = int(proc.InitFile(f, cmd.extraFiles))
-		cmd.files = append(cmd.files, f)
-		cmd.hasArgsFd = true
+		argsFd = int(proc.InitFile(f, hl.extraFiles))
+		hl.files = append(hl.files, f)
 	}
-	cmd.argF = func(statFd int) []string { return argF(argsFd, statFd) }
 
+	statFd := -1
+	if hl.useStatFd {
+		f := proc.NewStat(&hl.stat)
+		statFd = int(proc.InitFile(f, hl.extraFiles))
+		hl.files = append(hl.files, f)
+	}
+
+	args = argF(argsFd, statFd)
 	return
 }
 
-// helperCmd wraps Cmd and implements methods shared across all Helper implementations.
-type helperCmd struct {
-	// ref to parent
-	r Helper
-
-	// returns an array of arguments passed directly
-	// to the helper process
-	argF func(statFd int) []string
+// helperFiles provides a generic wrapper around helper ipc.
+type helperFiles struct {
 	// whether argsFd is present
-	hasArgsFd bool
+	useArgsFd bool
+	// whether statFd is present
+	useStatFd bool
 
 	// closes statFd
 	stat io.Closer
@@ -90,45 +79,5 @@ type helperCmd struct {
 	// passed through to [proc.Fulfill] and [proc.InitFile]
 	extraFiles *proc.ExtraFilesPre
 
-	name           string
-	stdin          io.Reader
-	stdout, stderr io.Writer
-	env            []string
-	*exec.Cmd
+	ctx context.Context
 }
-
-func (h *helperCmd) Stdin(r io.Reader) Helper   { h.stdin = r; return h.r }
-func (h *helperCmd) Stdout(w io.Writer) Helper  { h.stdout = w; return h.r }
-func (h *helperCmd) Stderr(w io.Writer) Helper  { h.stderr = w; return h.r }
-func (h *helperCmd) SetEnv(env []string) Helper { h.env = env; return h.r }
-
-// finalise initialises the underlying [exec.Cmd] object.
-func (h *helperCmd) finalise(ctx context.Context, stat bool) (args []string) {
-	h.Cmd = commandContext(ctx, h.name)
-	h.Cmd.Stdin, h.Cmd.Stdout, h.Cmd.Stderr = h.stdin, h.stdout, h.stderr
-	h.Cmd.Env = slices.Grow(h.env, 2)
-	if h.hasArgsFd {
-		h.Cmd.Env = append(h.Cmd.Env, FortifyHelper+"=1")
-	} else {
-		h.Cmd.Env = append(h.Cmd.Env, FortifyHelper+"=0")
-	}
-
-	h.Cmd.Cancel = func() error { return h.Cmd.Process.Signal(syscall.SIGTERM) }
-	h.Cmd.WaitDelay = WaitDelay
-
-	statFd := -1
-	if stat {
-		f := proc.NewStat(&h.stat)
-		statFd = int(proc.InitFile(f, h.extraFiles))
-		h.files = append(h.files, f)
-		h.Cmd.Env = append(h.Cmd.Env, FortifyStatus+"=1")
-
-		// stat is populated on fulfill
-		h.Cmd.Cancel = func() error { return h.stat.Close() }
-	} else {
-		h.Cmd.Env = append(h.Cmd.Env, FortifyStatus+"=0")
-	}
-	return h.argF(statFd)
-}
-
-var commandContext = exec.CommandContext

helper/helper_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"strconv"
 	"strings"
 	"testing"
@@ -35,7 +36,8 @@ func argF(argsFd, statFd int) []string {
 }
 
 func argFChecked(argsFd, statFd int) (args []string) {
-	args = make([]string, 0, 4)
+	args = make([]string, 0, 6)
+	args = append(args, "-test.run=TestHelperStub", "--")
 	if argsFd > -1 {
 		args = append(args, "--args", strconv.Itoa(argsFd))
 	}
@@ -46,14 +48,15 @@ func argFChecked(argsFd, statFd int) (args []string) {
 }
 
 // this function tests an implementation of the helper.Helper interface
-func testHelper(t *testing.T, createHelper func() helper.Helper) {
-	helper.InternalReplaceExecCommand(t)
+func testHelper(t *testing.T, createHelper func(ctx context.Context, setOutput func(stdoutP, stderrP *io.Writer), stat bool) helper.Helper) {
+	oldWaitDelay := helper.WaitDelay
+	helper.WaitDelay = 16 * time.Second
+	t.Cleanup(func() { helper.WaitDelay = oldWaitDelay })
 
 	t.Run("start helper with status channel and wait", func(t *testing.T) {
-		h := createHelper()
-
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		stdout, stderr := new(strings.Builder), new(strings.Builder)
-		h.Stdout(stdout).Stderr(stderr)
+		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, stderr }, true)
 
 		t.Run("wait not yet started helper", func(t *testing.T) {
 			defer func() {
@@ -65,10 +68,8 @@ func testHelper(t *testing.T, createHelper func() helper.Helper) {
 			panic(fmt.Sprintf("unreachable: %v", h.Wait()))
 		})
 
-		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-
 		t.Log("starting helper stub")
-		if err := h.Start(ctx, true); err != nil {
+		if err := h.Start(); err != nil {
 			t.Errorf("Start: error = %v", err)
 			cancel()
 			return
@@ -77,8 +78,8 @@ func testHelper(t *testing.T, createHelper func() helper.Helper) {
 		cancel()
 
 		t.Run("start already started helper", func(t *testing.T) {
-			wantErr := "exec: already started"
-			if err := h.Start(ctx, true); err != nil && err.Error() != wantErr {
+			wantErr := "helper: already started"
+			if err := h.Start(); err != nil && err.Error() != wantErr {
 				t.Errorf("Start: error = %v, wantErr %v",
 					err, wantErr)
 				return
@@ -100,21 +101,19 @@ func testHelper(t *testing.T, createHelper func() helper.Helper) {
 			}
 		})
 
-		if got := stdout.String(); !strings.HasPrefix(got, wantPayload) {
-			t.Errorf("Start: stdout = %v, want %v",
+		if got := stderr.String(); got != wantPayload {
+			t.Errorf("Start: stderr = %v, want %v",
 				got, wantPayload)
 		}
 	})
 
 	t.Run("start helper and wait", func(t *testing.T) {
-		h := createHelper()
-
-		stdout, stderr := new(strings.Builder), new(strings.Builder)
-		h.Stdout(stdout).Stderr(stderr)
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		defer cancel()
+		stdout, stderr := new(strings.Builder), new(strings.Builder)
+		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, stderr }, false)
 
-		if err := h.Start(ctx, false); err != nil {
+		if err := h.Start(); err != nil {
 			t.Errorf("Start() error = %v",
 				err)
 			return
@@ -125,8 +124,8 @@ func testHelper(t *testing.T, createHelper func() helper.Helper) {
 				err, stdout, stderr)
 		}
 
-		if got := stdout.String(); !strings.HasPrefix(got, wantPayload) {
-			t.Errorf("Start() stdout = %v, want %v",
+		if got := stderr.String(); got != wantPayload {
+			t.Errorf("Start() stderr = %v, want %v",
 				got, wantPayload)
 		}
 	})

helper/proc/files.go

@@ -60,7 +60,10 @@ func (f *ExtraFilesPre) copy(e []*os.File) []*os.File {
 }
 
 // Fulfill calls the [File.Fulfill] method on all files, starts cmd and blocks until all fulfillment completes.
-func Fulfill(ctx context.Context, cmd *exec.Cmd, files []File, extraFiles *ExtraFilesPre) (err error) {
+func Fulfill(ctx context.Context,
+	v *[]*os.File, start func() error,
+	files []File, extraFiles *ExtraFilesPre,
+) (err error) {
 	var ecs int
 	for _, o := range files {
 		ecs += o.ErrCount()
@@ -77,8 +80,8 @@ func Fulfill(ctx context.Context, cmd *exec.Cmd, files []File, extraFiles *Extra
 		}
 	}
 
-	cmd.ExtraFiles = extraFiles.Files()
-	if err = cmd.Start(); err != nil {
+	*v = extraFiles.Files()
+	if err = start(); err != nil {
 		return
 	}
 

helper/stub.go

@@ -1,25 +1,17 @@
 package helper
 
 import (
-	"context"
 	"flag"
 	"fmt"
 	"io"
 	"os"
-	"os/exec"
 	"strconv"
-	"strings"
 	"syscall"
-	"testing"
-
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/internal"
 )
 
-// InternalChildStub is an internal function but exported because it is cross-package;
+// InternalHelperStub is an internal function but exported because it is cross-package;
 // it is part of the implementation of the helper stub.
-func InternalChildStub() {
+func InternalHelperStub() {
 	// this test mocks the helper process
 	var ap, sp string
 	if v, ok := os.LookupEnv(FortifyHelper); !ok {
@@ -33,30 +25,9 @@ func InternalChildStub() {
 		sp = v
 	}
 
-	switch os.Args[3] {
-	case "bwrap":
-		bwrapStub()
-	default:
-		genericStub(flagRestoreFiles(4, ap, sp))
-	}
+	genericStub(flagRestoreFiles(3, ap, sp))
 
-	internal.Exit(0)
-}
-
-// InternalReplaceExecCommand is an internal function but exported because it is cross-package;
-// it is part of the implementation of the helper stub.
-func InternalReplaceExecCommand(t *testing.T) {
-	t.Cleanup(func() { commandContext = exec.CommandContext })
-
-	// replace execCommand to have the resulting *exec.Cmd launch TestHelperChildStub
-	commandContext = func(ctx context.Context, name string, arg ...string) *exec.Cmd {
-		// pass through nonexistent path
-		if name == "/nonexistent" && len(arg) == 0 {
-			return exec.CommandContext(ctx, name)
-		}
-
-		return exec.CommandContext(ctx, os.Args[0], append([]string{"-test.run=TestHelperChildStub", "--", name}, arg...)...)
-	}
+	os.Exit(0)
 }
 
 func newFile(fd int, name, p string) *os.File {
@@ -92,7 +63,7 @@ func flagRestoreFiles(offset int, ap, sp string) (argsFile, statFile *os.File) {
 func genericStub(argsFile, statFile *os.File) {
 	if argsFile != nil {
 		// this output is checked by parent
-		if _, err := io.Copy(os.Stdout, argsFile); err != nil {
+		if _, err := io.Copy(os.Stderr, argsFile); err != nil {
 			panic("cannot read args: " + err.Error())
 		}
 	}
@@ -133,42 +104,3 @@ func genericStub(argsFile, statFile *os.File) {
 		<-done
 	}
 }
-
-func bwrapStub() {
-	// the bwrap launcher does not launch with a typical sync fd
-	argsFile, _ := flagRestoreFiles(4, "1", "0")
-
-	// test args pipe behaviour
-	func() {
-		got, want := new(strings.Builder), new(strings.Builder)
-		if _, err := io.Copy(got, argsFile); err != nil {
-			panic("cannot read bwrap args: " + err.Error())
-		}
-
-		// hardcoded bwrap configuration used by test
-		sc := &bwrap.Config{
-			Net:           true,
-			Hostname:      "localhost",
-			Chdir:         "/nonexistent",
-			Clearenv:      true,
-			NewSession:    true,
-			DieWithParent: true,
-			AsInit:        true,
-		}
-		if _, err := MustNewCheckedArgs(sc.Args(nil, new(proc.ExtraFilesPre), new([]proc.File))).
-			WriteTo(want); err != nil {
-			panic("cannot read want: " + err.Error())
-		}
-
-		if len(flag.CommandLine.Args()) > 0 && flag.CommandLine.Args()[0] == "crash-test-dummy" && got.String() != want.String() {
-			panic("bad bwrap args\ngot: " + got.String() + "\nwant: " + want.String())
-		}
-	}()
-
-	if err := syscall.Exec(
-		os.Args[0],
-		append([]string{os.Args[0], "-test.run=TestHelperChildStub", "--"}, flag.CommandLine.Args()...),
-		os.Environ()); err != nil {
-		panic("cannot start general stub: " + err.Error())
-	}
-}

helper/stub_test.go

@@ -6,6 +6,4 @@ import (
 	"git.gensokyo.uk/security/fortify/helper"
 )
 
-func TestHelperChildStub(t *testing.T) {
-	helper.InternalChildStub()
-}
+func TestHelperStub(t *testing.T) { helper.InternalHelperStub() }

internal/app/app.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"sync"
@@ -10,9 +11,10 @@ import (
 	"git.gensokyo.uk/security/fortify/internal/sys"
 )
 
-func New(os sys.State) (fst.App, error) {
+func New(ctx context.Context, os sys.State) (fst.App, error) {
 	a := new(app)
 	a.sys = os
+	a.ctx = ctx
 
 	id := new(fst.ID)
 	err := fst.NewAppID(id)
@@ -21,8 +23,8 @@ func New(os sys.State) (fst.App, error) {
 	return a, err
 }
 
-func MustNew(os sys.State) fst.App {
-	a, err := New(os)
+func MustNew(ctx context.Context, os sys.State) fst.App {
+	a, err := New(ctx, os)
 	if err != nil {
 		log.Fatalf("cannot create app: %v", err)
 	}
@@ -32,6 +34,7 @@ func MustNew(os sys.State) fst.App {
 type app struct {
 	id  *stringPair[fst.ID]
 	sys sys.State
+	ctx context.Context
 
 	*outcome
 	mu sync.RWMutex
@@ -71,7 +74,7 @@ func (a *app) Seal(config *fst.Config) (fst.SealedApp, error) {
 
 	seal := new(outcome)
 	seal.id = a.id
-	err := seal.finalise(a.sys, config)
+	err := seal.finalise(a.ctx, a.sys, config)
 	if err == nil {
 		a.outcome = seal
 	}

internal/app/app_nixos_test.go

@@ -4,7 +4,7 @@ import (
 	"git.gensokyo.uk/security/fortify/acl"
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
+	"git.gensokyo.uk/security/fortify/sandbox"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
@@ -12,20 +12,20 @@ var testCasesNixos = []sealTestCase{
 	{
 		"nixos chromium direct wayland", new(stubNixOS),
 		&fst.Config{
-			ID:      "org.chromium.Chromium",
-			Command: []string{"/nix/store/yqivzpzzn7z5x0lq9hmbzygh45d8rhqd-chromium-start"},
+			ID:   "org.chromium.Chromium",
+			Path: "/nix/store/yqivzpzzn7z5x0lq9hmbzygh45d8rhqd-chromium-start",
 			Confinement: fst.ConfinementConfig{
 				AppID: 1, Groups: []string{}, Username: "u0_a1",
 				Outer: "/var/lib/persist/module/fortify/0/1",
 				Sandbox: &fst.SandboxConfig{
-					UserNS: true, Net: true, MapRealUID: true, DirectWayland: true, Env: nil, AutoEtc: true,
+					Userns: true, Net: true, MapRealUID: true, DirectWayland: true, Env: nil, AutoEtc: true,
 					Filesystem: []*fst.FilesystemConfig{
 						{Src: "/bin", Must: true}, {Src: "/usr/bin", Must: true},
 						{Src: "/nix/store", Must: true}, {Src: "/run/current-system", Must: true},
 						{Src: "/sys/block"}, {Src: "/sys/bus"}, {Src: "/sys/class"}, {Src: "/sys/dev"}, {Src: "/sys/devices"},
 						{Src: "/run/opengl-driver", Must: true}, {Src: "/dev/dri", Device: true},
 					},
-					Override: []string{"/var/run/nscd"},
+					Cover: []string{"/var/run/nscd"},
 				},
 				SystemBus: &dbus.Config{
 					Talk:   []string{"org.bluez", "org.freedesktop.Avahi", "org.freedesktop.UPower"},
@@ -45,7 +45,7 @@ var testCasesNixos = []sealTestCase{
 					Call: map[string]string{}, Broadcast: map[string]string{},
 					Filter: true,
 				},
-				Enablements: system.EWayland.Mask() | system.EDBus.Mask() | system.EPulse.Mask(),
+				Enablements: system.EWayland | system.EDBus | system.EPulse,
 			},
 		},
 		fst.ID{
@@ -88,136 +88,132 @@ var testCasesNixos = []sealTestCase{
 			}).
 			UpdatePerm("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/bus", acl.Read, acl.Write).
 			UpdatePerm("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/system_bus_socket", acl.Read, acl.Write),
-		(&bwrap.Config{
-			Net:      true,
-			UserNS:   true,
-			Chdir:    "/var/lib/persist/module/fortify/0/1",
-			Clearenv: true,
-			SetEnv: map[string]string{
-				"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/1971/bus",
-				"DBUS_SYSTEM_BUS_ADDRESS":  "unix:path=/run/dbus/system_bus_socket",
-				"HOME":                     "/var/lib/persist/module/fortify/0/1",
-				"PULSE_COOKIE":             fst.Tmp + "/pulse-cookie",
-				"PULSE_SERVER":             "unix:/run/user/1971/pulse/native",
-				"SHELL":                    "/run/current-system/sw/bin/zsh",
-				"TERM":                     "xterm-256color",
-				"USER":                     "u0_a1",
-				"WAYLAND_DISPLAY":          "wayland-0",
-				"XDG_RUNTIME_DIR":          "/run/user/1971",
-				"XDG_SESSION_CLASS":        "user",
-				"XDG_SESSION_TYPE":         "tty",
+		&sandbox.Params{
+			Uid:   1971,
+			Gid:   100,
+			Flags: sandbox.FAllowNet | sandbox.FAllowUserns,
+			Dir:   "/var/lib/persist/module/fortify/0/1",
+			Path:  "/nix/store/yqivzpzzn7z5x0lq9hmbzygh45d8rhqd-chromium-start",
+			Args:  []string{"/nix/store/yqivzpzzn7z5x0lq9hmbzygh45d8rhqd-chromium-start"},
+			Env: []string{
+				"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1971/bus",
+				"DBUS_SYSTEM_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket",
+				"HOME=/var/lib/persist/module/fortify/0/1",
+				"PULSE_COOKIE=" + fst.Tmp + "/pulse-cookie",
+				"PULSE_SERVER=unix:/run/user/1971/pulse/native",
+				"TERM=xterm-256color",
+				"USER=u0_a1",
+				"WAYLAND_DISPLAY=wayland-0",
+				"XDG_RUNTIME_DIR=/run/user/1971",
+				"XDG_SESSION_CLASS=user",
+				"XDG_SESSION_TYPE=tty",
 			},
-			Chmod:         make(bwrap.ChmodConfig),
-			NewSession:    true,
-			DieWithParent: true,
-			AsInit:        true,
-		}).SetUID(1971).SetGID(1971).
-			Procfs("/proc").
-			Tmpfs(fst.Tmp, 4096).
-			DevTmpfs("/dev").Mqueue("/dev/mqueue").
-			Bind("/bin", "/bin").
-			Bind("/usr/bin", "/usr/bin").
-			Bind("/nix/store", "/nix/store").
-			Bind("/run/current-system", "/run/current-system").
-			Bind("/sys/block", "/sys/block", true).
-			Bind("/sys/bus", "/sys/bus", true).
-			Bind("/sys/class", "/sys/class", true).
-			Bind("/sys/dev", "/sys/dev", true).
-			Bind("/sys/devices", "/sys/devices", true).
-			Bind("/run/opengl-driver", "/run/opengl-driver").
-			Bind("/dev/dri", "/dev/dri", true, true, true).
-			Bind("/etc", fst.Tmp+"/etc").
-			Symlink(fst.Tmp+"/etc/alsa", "/etc/alsa").
-			Symlink(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
-			Symlink(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
-			Symlink(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
-			Symlink(fst.Tmp+"/etc/default", "/etc/default").
-			Symlink(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
-			Symlink(fst.Tmp+"/etc/fonts", "/etc/fonts").
-			Symlink(fst.Tmp+"/etc/fstab", "/etc/fstab").
-			Symlink(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
-			Symlink(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
-			Symlink(fst.Tmp+"/etc/hostid", "/etc/hostid").
-			Symlink(fst.Tmp+"/etc/hostname", "/etc/hostname").
-			Symlink(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
-			Symlink(fst.Tmp+"/etc/hosts", "/etc/hosts").
-			Symlink(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
-			Symlink(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
-			Symlink(fst.Tmp+"/etc/issue", "/etc/issue").
-			Symlink(fst.Tmp+"/etc/kbd", "/etc/kbd").
-			Symlink(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
-			Symlink(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
-			Symlink(fst.Tmp+"/etc/localtime", "/etc/localtime").
-			Symlink(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
-			Symlink(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
-			Symlink(fst.Tmp+"/etc/lvm", "/etc/lvm").
-			Symlink(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
-			Symlink(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
-			Symlink(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
-			Symlink(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
-			Symlink("/proc/mounts", "/etc/mtab").
-			Symlink(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
-			Symlink(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
-			Symlink(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
-			Symlink(fst.Tmp+"/etc/nix", "/etc/nix").
-			Symlink(fst.Tmp+"/etc/nixos", "/etc/nixos").
-			Symlink(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
-			Symlink(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
-			Symlink(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
-			Symlink(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
-			Symlink(fst.Tmp+"/etc/os-release", "/etc/os-release").
-			Symlink(fst.Tmp+"/etc/pam", "/etc/pam").
-			Symlink(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
-			Symlink(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
-			Symlink(fst.Tmp+"/etc/pki", "/etc/pki").
-			Symlink(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
-			Symlink(fst.Tmp+"/etc/profile", "/etc/profile").
-			Symlink(fst.Tmp+"/etc/protocols", "/etc/protocols").
-			Symlink(fst.Tmp+"/etc/qemu", "/etc/qemu").
-			Symlink(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
-			Symlink(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
-			Symlink(fst.Tmp+"/etc/rpc", "/etc/rpc").
-			Symlink(fst.Tmp+"/etc/samba", "/etc/samba").
-			Symlink(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
-			Symlink(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
-			Symlink(fst.Tmp+"/etc/services", "/etc/services").
-			Symlink(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
-			Symlink(fst.Tmp+"/etc/shadow", "/etc/shadow").
-			Symlink(fst.Tmp+"/etc/shells", "/etc/shells").
-			Symlink(fst.Tmp+"/etc/ssh", "/etc/ssh").
-			Symlink(fst.Tmp+"/etc/ssl", "/etc/ssl").
-			Symlink(fst.Tmp+"/etc/static", "/etc/static").
-			Symlink(fst.Tmp+"/etc/subgid", "/etc/subgid").
-			Symlink(fst.Tmp+"/etc/subuid", "/etc/subuid").
-			Symlink(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
-			Symlink(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
-			Symlink(fst.Tmp+"/etc/systemd", "/etc/systemd").
-			Symlink(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
-			Symlink(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
-			Symlink(fst.Tmp+"/etc/udev", "/etc/udev").
-			Symlink(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
-			Symlink(fst.Tmp+"/etc/UPower", "/etc/UPower").
-			Symlink(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
-			Symlink(fst.Tmp+"/etc/X11", "/etc/X11").
-			Symlink(fst.Tmp+"/etc/zfs", "/etc/zfs").
-			Symlink(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
-			Symlink(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
-			Symlink(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
-			Symlink(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
-			Symlink(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/1971", 8388608).
-			Bind("/tmp/fortify.1971/tmpdir/1", "/tmp", false, true).
-			Bind("/var/lib/persist/module/fortify/0/1", "/var/lib/persist/module/fortify/0/1", false, true).
-			CopyBind("/etc/passwd", []byte("u0_a1:x:1971:1971:Fortify:/var/lib/persist/module/fortify/0/1:/run/current-system/sw/bin/zsh\n")).
-			CopyBind("/etc/group", []byte("fortify:x:1971:\n")).
-			Bind("/run/user/1971/wayland-0", "/run/user/1971/wayland-0").
-			Bind("/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1/pulse", "/run/user/1971/pulse/native").
-			CopyBind(fst.Tmp+"/pulse-cookie", nil).
-			Bind("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/bus", "/run/user/1971/bus").
-			Bind("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/system_bus_socket", "/run/dbus/system_bus_socket").
-			Tmpfs("/var/run/nscd", 8192).
-			Bind("/run/wrappers/bin/fortify", "/.fortify/sbin/fortify").
-			Symlink("fortify", "/.fortify/sbin/init"),
+			Ops: new(sandbox.Ops).
+				Proc("/proc").
+				Tmpfs(fst.Tmp, 4096, 0755).
+				Dev("/dev").Mqueue("/dev/mqueue").
+				Bind("/bin", "/bin", 0).
+				Bind("/usr/bin", "/usr/bin", 0).
+				Bind("/nix/store", "/nix/store", 0).
+				Bind("/run/current-system", "/run/current-system", 0).
+				Bind("/sys/block", "/sys/block", sandbox.BindOptional).
+				Bind("/sys/bus", "/sys/bus", sandbox.BindOptional).
+				Bind("/sys/class", "/sys/class", sandbox.BindOptional).
+				Bind("/sys/dev", "/sys/dev", sandbox.BindOptional).
+				Bind("/sys/devices", "/sys/devices", sandbox.BindOptional).
+				Bind("/run/opengl-driver", "/run/opengl-driver", 0).
+				Bind("/dev/dri", "/dev/dri", sandbox.BindDevice|sandbox.BindWritable|sandbox.BindOptional).
+				Bind("/etc", fst.Tmp+"/etc", 0).
+				Link(fst.Tmp+"/etc/alsa", "/etc/alsa").
+				Link(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
+				Link(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
+				Link(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
+				Link(fst.Tmp+"/etc/default", "/etc/default").
+				Link(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
+				Link(fst.Tmp+"/etc/fonts", "/etc/fonts").
+				Link(fst.Tmp+"/etc/fstab", "/etc/fstab").
+				Link(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
+				Link(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
+				Link(fst.Tmp+"/etc/hostid", "/etc/hostid").
+				Link(fst.Tmp+"/etc/hostname", "/etc/hostname").
+				Link(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
+				Link(fst.Tmp+"/etc/hosts", "/etc/hosts").
+				Link(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
+				Link(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
+				Link(fst.Tmp+"/etc/issue", "/etc/issue").
+				Link(fst.Tmp+"/etc/kbd", "/etc/kbd").
+				Link(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
+				Link(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
+				Link(fst.Tmp+"/etc/localtime", "/etc/localtime").
+				Link(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
+				Link(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
+				Link(fst.Tmp+"/etc/lvm", "/etc/lvm").
+				Link(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
+				Link(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
+				Link(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
+				Link(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
+				Link("/proc/mounts", "/etc/mtab").
+				Link(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
+				Link(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
+				Link(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
+				Link(fst.Tmp+"/etc/nix", "/etc/nix").
+				Link(fst.Tmp+"/etc/nixos", "/etc/nixos").
+				Link(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
+				Link(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
+				Link(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
+				Link(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
+				Link(fst.Tmp+"/etc/os-release", "/etc/os-release").
+				Link(fst.Tmp+"/etc/pam", "/etc/pam").
+				Link(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
+				Link(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
+				Link(fst.Tmp+"/etc/pki", "/etc/pki").
+				Link(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
+				Link(fst.Tmp+"/etc/profile", "/etc/profile").
+				Link(fst.Tmp+"/etc/protocols", "/etc/protocols").
+				Link(fst.Tmp+"/etc/qemu", "/etc/qemu").
+				Link(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
+				Link(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
+				Link(fst.Tmp+"/etc/rpc", "/etc/rpc").
+				Link(fst.Tmp+"/etc/samba", "/etc/samba").
+				Link(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
+				Link(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
+				Link(fst.Tmp+"/etc/services", "/etc/services").
+				Link(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
+				Link(fst.Tmp+"/etc/shadow", "/etc/shadow").
+				Link(fst.Tmp+"/etc/shells", "/etc/shells").
+				Link(fst.Tmp+"/etc/ssh", "/etc/ssh").
+				Link(fst.Tmp+"/etc/ssl", "/etc/ssl").
+				Link(fst.Tmp+"/etc/static", "/etc/static").
+				Link(fst.Tmp+"/etc/subgid", "/etc/subgid").
+				Link(fst.Tmp+"/etc/subuid", "/etc/subuid").
+				Link(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
+				Link(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
+				Link(fst.Tmp+"/etc/systemd", "/etc/systemd").
+				Link(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
+				Link(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
+				Link(fst.Tmp+"/etc/udev", "/etc/udev").
+				Link(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
+				Link(fst.Tmp+"/etc/UPower", "/etc/UPower").
+				Link(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
+				Link(fst.Tmp+"/etc/X11", "/etc/X11").
+				Link(fst.Tmp+"/etc/zfs", "/etc/zfs").
+				Link(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
+				Link(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
+				Link(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
+				Link(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
+				Link(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
+				Tmpfs("/run/user", 4096, 0755).
+				Tmpfs("/run/user/1971", 8388608, 0700).
+				Bind("/tmp/fortify.1971/tmpdir/1", "/tmp", sandbox.BindWritable).
+				Bind("/var/lib/persist/module/fortify/0/1", "/var/lib/persist/module/fortify/0/1", sandbox.BindWritable).
+				Place("/etc/passwd", []byte("u0_a1:x:1971:100:Fortify:/var/lib/persist/module/fortify/0/1:/run/current-system/sw/bin/zsh\n")).
+				Place("/etc/group", []byte("fortify:x:100:\n")).
+				Bind("/run/user/1971/wayland-0", "/run/user/1971/wayland-0", 0).
+				Bind("/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1/pulse", "/run/user/1971/pulse/native", 0).
+				Place(fst.Tmp+"/pulse-cookie", nil).
+				Bind("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/bus", "/run/user/1971/bus", 0).
+				Bind("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/system_bus_socket", "/run/dbus/system_bus_socket", 0).
+				Tmpfs("/var/run/nscd", 8192, 0755),
+		},
 	},
 }

internal/app/app_pd_test.go

@@ -6,7 +6,7 @@ import (
 	"git.gensokyo.uk/security/fortify/acl"
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
+	"git.gensokyo.uk/security/fortify/sandbox"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
@@ -14,7 +14,6 @@ var testCasesPd = []sealTestCase{
 	{
 		"nixos permissive defaults no enablements", new(stubNixOS),
 		&fst.Config{
-			Command: make([]string, 0),
 			Confinement: fst.ConfinementConfig{
 				AppID:    0,
 				Username: "chronos",
@@ -35,136 +34,131 @@ var testCasesPd = []sealTestCase{
 			Ephemeral(system.Process, "/run/user/1971/fortify/4a450b6596d7bc15bd01780eb9a607ac", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/4a450b6596d7bc15bd01780eb9a607ac", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir", 0700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir/0", 01700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir/0", acl.Read, acl.Write, acl.Execute),
-		(&bwrap.Config{
-			Net:      true,
-			UserNS:   true,
-			Clearenv: true,
-			Syscall:  new(bwrap.SyscallPolicy),
-			Chdir:    "/home/chronos",
-			SetEnv: map[string]string{
-				"HOME":              "/home/chronos",
-				"SHELL":             "/run/current-system/sw/bin/zsh",
-				"TERM":              "xterm-256color",
-				"USER":              "chronos",
-				"XDG_RUNTIME_DIR":   "/run/user/65534",
-				"XDG_SESSION_CLASS": "user",
-				"XDG_SESSION_TYPE":  "tty"},
-			Chmod:         make(bwrap.ChmodConfig),
-			DieWithParent: true,
-			AsInit:        true,
-		}).SetUID(65534).SetGID(65534).
-			Procfs("/proc").
-			Tmpfs(fst.Tmp, 4096).
-			DevTmpfs("/dev").Mqueue("/dev/mqueue").
-			Bind("/bin", "/bin", false, true).
-			Bind("/boot", "/boot", false, true).
-			Bind("/home", "/home", false, true).
-			Bind("/lib", "/lib", false, true).
-			Bind("/lib64", "/lib64", false, true).
-			Bind("/nix", "/nix", false, true).
-			Bind("/root", "/root", false, true).
-			Bind("/run", "/run", false, true).
-			Bind("/srv", "/srv", false, true).
-			Bind("/sys", "/sys", false, true).
-			Bind("/usr", "/usr", false, true).
-			Bind("/var", "/var", false, true).
-			Bind("/dev/kvm", "/dev/kvm", true, true, true).
-			Tmpfs("/run/user/1971", 8192).
-			Tmpfs("/run/dbus", 8192).
-			Bind("/etc", fst.Tmp+"/etc").
-			Symlink(fst.Tmp+"/etc/alsa", "/etc/alsa").
-			Symlink(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
-			Symlink(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
-			Symlink(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
-			Symlink(fst.Tmp+"/etc/default", "/etc/default").
-			Symlink(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
-			Symlink(fst.Tmp+"/etc/fonts", "/etc/fonts").
-			Symlink(fst.Tmp+"/etc/fstab", "/etc/fstab").
-			Symlink(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
-			Symlink(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
-			Symlink(fst.Tmp+"/etc/hostid", "/etc/hostid").
-			Symlink(fst.Tmp+"/etc/hostname", "/etc/hostname").
-			Symlink(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
-			Symlink(fst.Tmp+"/etc/hosts", "/etc/hosts").
-			Symlink(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
-			Symlink(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
-			Symlink(fst.Tmp+"/etc/issue", "/etc/issue").
-			Symlink(fst.Tmp+"/etc/kbd", "/etc/kbd").
-			Symlink(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
-			Symlink(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
-			Symlink(fst.Tmp+"/etc/localtime", "/etc/localtime").
-			Symlink(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
-			Symlink(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
-			Symlink(fst.Tmp+"/etc/lvm", "/etc/lvm").
-			Symlink(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
-			Symlink(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
-			Symlink(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
-			Symlink(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
-			Symlink("/proc/mounts", "/etc/mtab").
-			Symlink(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
-			Symlink(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
-			Symlink(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
-			Symlink(fst.Tmp+"/etc/nix", "/etc/nix").
-			Symlink(fst.Tmp+"/etc/nixos", "/etc/nixos").
-			Symlink(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
-			Symlink(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
-			Symlink(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
-			Symlink(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
-			Symlink(fst.Tmp+"/etc/os-release", "/etc/os-release").
-			Symlink(fst.Tmp+"/etc/pam", "/etc/pam").
-			Symlink(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
-			Symlink(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
-			Symlink(fst.Tmp+"/etc/pki", "/etc/pki").
-			Symlink(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
-			Symlink(fst.Tmp+"/etc/profile", "/etc/profile").
-			Symlink(fst.Tmp+"/etc/protocols", "/etc/protocols").
-			Symlink(fst.Tmp+"/etc/qemu", "/etc/qemu").
-			Symlink(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
-			Symlink(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
-			Symlink(fst.Tmp+"/etc/rpc", "/etc/rpc").
-			Symlink(fst.Tmp+"/etc/samba", "/etc/samba").
-			Symlink(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
-			Symlink(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
-			Symlink(fst.Tmp+"/etc/services", "/etc/services").
-			Symlink(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
-			Symlink(fst.Tmp+"/etc/shadow", "/etc/shadow").
-			Symlink(fst.Tmp+"/etc/shells", "/etc/shells").
-			Symlink(fst.Tmp+"/etc/ssh", "/etc/ssh").
-			Symlink(fst.Tmp+"/etc/ssl", "/etc/ssl").
-			Symlink(fst.Tmp+"/etc/static", "/etc/static").
-			Symlink(fst.Tmp+"/etc/subgid", "/etc/subgid").
-			Symlink(fst.Tmp+"/etc/subuid", "/etc/subuid").
-			Symlink(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
-			Symlink(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
-			Symlink(fst.Tmp+"/etc/systemd", "/etc/systemd").
-			Symlink(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
-			Symlink(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
-			Symlink(fst.Tmp+"/etc/udev", "/etc/udev").
-			Symlink(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
-			Symlink(fst.Tmp+"/etc/UPower", "/etc/UPower").
-			Symlink(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
-			Symlink(fst.Tmp+"/etc/X11", "/etc/X11").
-			Symlink(fst.Tmp+"/etc/zfs", "/etc/zfs").
-			Symlink(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
-			Symlink(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
-			Symlink(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
-			Symlink(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
-			Symlink(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/65534", 8388608).
-			Bind("/tmp/fortify.1971/tmpdir/0", "/tmp", false, true).
-			Bind("/home/chronos", "/home/chronos", false, true).
-			CopyBind("/etc/passwd", []byte("chronos:x:65534:65534:Fortify:/home/chronos:/run/current-system/sw/bin/zsh\n")).
-			CopyBind("/etc/group", []byte("fortify:x:65534:\n")).
-			Tmpfs("/var/run/nscd", 8192).
-			Bind("/run/wrappers/bin/fortify", "/.fortify/sbin/fortify").
-			Symlink("fortify", "/.fortify/sbin/init"),
+		&sandbox.Params{
+			Flags: sandbox.FAllowNet | sandbox.FAllowUserns | sandbox.FAllowTTY,
+			Dir:   "/home/chronos",
+			Path:  "/run/current-system/sw/bin/zsh",
+			Args:  []string{"/run/current-system/sw/bin/zsh"},
+			Env: []string{
+				"HOME=/home/chronos",
+				"TERM=xterm-256color",
+				"USER=chronos",
+				"XDG_RUNTIME_DIR=/run/user/65534",
+				"XDG_SESSION_CLASS=user",
+				"XDG_SESSION_TYPE=tty",
+			},
+			Ops: new(sandbox.Ops).
+				Proc("/proc").
+				Tmpfs(fst.Tmp, 4096, 0755).
+				Dev("/dev").Mqueue("/dev/mqueue").
+				Bind("/bin", "/bin", sandbox.BindWritable).
+				Bind("/boot", "/boot", sandbox.BindWritable).
+				Bind("/home", "/home", sandbox.BindWritable).
+				Bind("/lib", "/lib", sandbox.BindWritable).
+				Bind("/lib64", "/lib64", sandbox.BindWritable).
+				Bind("/nix", "/nix", sandbox.BindWritable).
+				Bind("/root", "/root", sandbox.BindWritable).
+				Bind("/run", "/run", sandbox.BindWritable).
+				Bind("/srv", "/srv", sandbox.BindWritable).
+				Bind("/sys", "/sys", sandbox.BindWritable).
+				Bind("/usr", "/usr", sandbox.BindWritable).
+				Bind("/var", "/var", sandbox.BindWritable).
+				Bind("/dev/kvm", "/dev/kvm", sandbox.BindWritable|sandbox.BindDevice|sandbox.BindOptional).
+				Tmpfs("/run/user/1971", 8192, 0755).
+				Tmpfs("/run/dbus", 8192, 0755).
+				Bind("/etc", fst.Tmp+"/etc", 0).
+				Link(fst.Tmp+"/etc/alsa", "/etc/alsa").
+				Link(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
+				Link(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
+				Link(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
+				Link(fst.Tmp+"/etc/default", "/etc/default").
+				Link(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
+				Link(fst.Tmp+"/etc/fonts", "/etc/fonts").
+				Link(fst.Tmp+"/etc/fstab", "/etc/fstab").
+				Link(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
+				Link(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
+				Link(fst.Tmp+"/etc/hostid", "/etc/hostid").
+				Link(fst.Tmp+"/etc/hostname", "/etc/hostname").
+				Link(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
+				Link(fst.Tmp+"/etc/hosts", "/etc/hosts").
+				Link(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
+				Link(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
+				Link(fst.Tmp+"/etc/issue", "/etc/issue").
+				Link(fst.Tmp+"/etc/kbd", "/etc/kbd").
+				Link(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
+				Link(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
+				Link(fst.Tmp+"/etc/localtime", "/etc/localtime").
+				Link(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
+				Link(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
+				Link(fst.Tmp+"/etc/lvm", "/etc/lvm").
+				Link(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
+				Link(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
+				Link(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
+				Link(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
+				Link("/proc/mounts", "/etc/mtab").
+				Link(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
+				Link(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
+				Link(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
+				Link(fst.Tmp+"/etc/nix", "/etc/nix").
+				Link(fst.Tmp+"/etc/nixos", "/etc/nixos").
+				Link(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
+				Link(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
+				Link(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
+				Link(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
+				Link(fst.Tmp+"/etc/os-release", "/etc/os-release").
+				Link(fst.Tmp+"/etc/pam", "/etc/pam").
+				Link(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
+				Link(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
+				Link(fst.Tmp+"/etc/pki", "/etc/pki").
+				Link(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
+				Link(fst.Tmp+"/etc/profile", "/etc/profile").
+				Link(fst.Tmp+"/etc/protocols", "/etc/protocols").
+				Link(fst.Tmp+"/etc/qemu", "/etc/qemu").
+				Link(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
+				Link(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
+				Link(fst.Tmp+"/etc/rpc", "/etc/rpc").
+				Link(fst.Tmp+"/etc/samba", "/etc/samba").
+				Link(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
+				Link(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
+				Link(fst.Tmp+"/etc/services", "/etc/services").
+				Link(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
+				Link(fst.Tmp+"/etc/shadow", "/etc/shadow").
+				Link(fst.Tmp+"/etc/shells", "/etc/shells").
+				Link(fst.Tmp+"/etc/ssh", "/etc/ssh").
+				Link(fst.Tmp+"/etc/ssl", "/etc/ssl").
+				Link(fst.Tmp+"/etc/static", "/etc/static").
+				Link(fst.Tmp+"/etc/subgid", "/etc/subgid").
+				Link(fst.Tmp+"/etc/subuid", "/etc/subuid").
+				Link(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
+				Link(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
+				Link(fst.Tmp+"/etc/systemd", "/etc/systemd").
+				Link(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
+				Link(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
+				Link(fst.Tmp+"/etc/udev", "/etc/udev").
+				Link(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
+				Link(fst.Tmp+"/etc/UPower", "/etc/UPower").
+				Link(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
+				Link(fst.Tmp+"/etc/X11", "/etc/X11").
+				Link(fst.Tmp+"/etc/zfs", "/etc/zfs").
+				Link(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
+				Link(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
+				Link(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
+				Link(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
+				Link(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
+				Tmpfs("/run/user", 4096, 0755).
+				Tmpfs("/run/user/65534", 8388608, 0700).
+				Bind("/tmp/fortify.1971/tmpdir/0", "/tmp", sandbox.BindWritable).
+				Bind("/home/chronos", "/home/chronos", sandbox.BindWritable).
+				Place("/etc/passwd", []byte("chronos:x:65534:65534:Fortify:/home/chronos:/run/current-system/sw/bin/zsh\n")).
+				Place("/etc/group", []byte("fortify:x:65534:\n")).
+				Tmpfs("/var/run/nscd", 8192, 0755),
+		},
 	},
 	{
 		"nixos permissive defaults chromium", new(stubNixOS),
 		&fst.Config{
-			ID:      "org.chromium.Chromium",
-			Command: []string{"/run/current-system/sw/bin/zsh", "-c", "exec chromium "},
+			ID:   "org.chromium.Chromium",
+			Args: []string{"zsh", "-c", "exec chromium "},
 			Confinement: fst.ConfinementConfig{
 				AppID:    9,
 				Groups:   []string{"video"},
@@ -201,7 +195,7 @@ var testCasesPd = []sealTestCase{
 					},
 					Filter: true,
 				},
-				Enablements: system.EWayland.Mask() | system.EDBus.Mask() | system.EPulse.Mask(),
+				Enablements: system.EWayland | system.EDBus | system.EPulse,
 			},
 		},
 		fst.ID{
@@ -254,141 +248,135 @@ var testCasesPd = []sealTestCase{
 			}).
 			UpdatePerm("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/bus", acl.Read, acl.Write).
 			UpdatePerm("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/system_bus_socket", acl.Read, acl.Write),
-		(&bwrap.Config{
-			Net:      true,
-			UserNS:   true,
-			Chdir:    "/home/chronos",
-			Clearenv: true,
-			Syscall:  new(bwrap.SyscallPolicy),
-			SetEnv: map[string]string{
-				"DBUS_SESSION_BUS_ADDRESS": "unix:path=/run/user/65534/bus",
-				"DBUS_SYSTEM_BUS_ADDRESS":  "unix:path=/run/dbus/system_bus_socket",
-				"HOME":                     "/home/chronos",
-				"PULSE_COOKIE":             fst.Tmp + "/pulse-cookie",
-				"PULSE_SERVER":             "unix:/run/user/65534/pulse/native",
-				"SHELL":                    "/run/current-system/sw/bin/zsh",
-				"TERM":                     "xterm-256color",
-				"USER":                     "chronos",
-				"WAYLAND_DISPLAY":          "wayland-0",
-				"XDG_RUNTIME_DIR":          "/run/user/65534",
-				"XDG_SESSION_CLASS":        "user",
-				"XDG_SESSION_TYPE":         "tty",
+		&sandbox.Params{
+			Flags: sandbox.FAllowNet | sandbox.FAllowUserns | sandbox.FAllowTTY,
+			Dir:   "/home/chronos",
+			Path:  "/run/current-system/sw/bin/zsh",
+			Args:  []string{"zsh", "-c", "exec chromium "},
+			Env: []string{
+				"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/65534/bus",
+				"DBUS_SYSTEM_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket",
+				"HOME=/home/chronos",
+				"PULSE_COOKIE=" + fst.Tmp + "/pulse-cookie",
+				"PULSE_SERVER=unix:/run/user/65534/pulse/native",
+				"TERM=xterm-256color",
+				"USER=chronos",
+				"WAYLAND_DISPLAY=wayland-0",
+				"XDG_RUNTIME_DIR=/run/user/65534",
+				"XDG_SESSION_CLASS=user",
+				"XDG_SESSION_TYPE=tty",
 			},
-			Chmod:         make(bwrap.ChmodConfig),
-			DieWithParent: true,
-			AsInit:        true,
-		}).SetUID(65534).SetGID(65534).
-			Procfs("/proc").
-			Tmpfs(fst.Tmp, 4096).
-			DevTmpfs("/dev").Mqueue("/dev/mqueue").
-			Bind("/bin", "/bin", false, true).
-			Bind("/boot", "/boot", false, true).
-			Bind("/home", "/home", false, true).
-			Bind("/lib", "/lib", false, true).
-			Bind("/lib64", "/lib64", false, true).
-			Bind("/nix", "/nix", false, true).
-			Bind("/root", "/root", false, true).
-			Bind("/run", "/run", false, true).
-			Bind("/srv", "/srv", false, true).
-			Bind("/sys", "/sys", false, true).
-			Bind("/usr", "/usr", false, true).
-			Bind("/var", "/var", false, true).
-			Bind("/dev/dri", "/dev/dri", true, true, true).
-			Bind("/dev/kvm", "/dev/kvm", true, true, true).
-			Tmpfs("/run/user/1971", 8192).
-			Tmpfs("/run/dbus", 8192).
-			Bind("/etc", fst.Tmp+"/etc").
-			Symlink(fst.Tmp+"/etc/alsa", "/etc/alsa").
-			Symlink(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
-			Symlink(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
-			Symlink(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
-			Symlink(fst.Tmp+"/etc/default", "/etc/default").
-			Symlink(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
-			Symlink(fst.Tmp+"/etc/fonts", "/etc/fonts").
-			Symlink(fst.Tmp+"/etc/fstab", "/etc/fstab").
-			Symlink(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
-			Symlink(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
-			Symlink(fst.Tmp+"/etc/hostid", "/etc/hostid").
-			Symlink(fst.Tmp+"/etc/hostname", "/etc/hostname").
-			Symlink(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
-			Symlink(fst.Tmp+"/etc/hosts", "/etc/hosts").
-			Symlink(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
-			Symlink(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
-			Symlink(fst.Tmp+"/etc/issue", "/etc/issue").
-			Symlink(fst.Tmp+"/etc/kbd", "/etc/kbd").
-			Symlink(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
-			Symlink(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
-			Symlink(fst.Tmp+"/etc/localtime", "/etc/localtime").
-			Symlink(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
-			Symlink(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
-			Symlink(fst.Tmp+"/etc/lvm", "/etc/lvm").
-			Symlink(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
-			Symlink(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
-			Symlink(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
-			Symlink(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
-			Symlink("/proc/mounts", "/etc/mtab").
-			Symlink(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
-			Symlink(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
-			Symlink(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
-			Symlink(fst.Tmp+"/etc/nix", "/etc/nix").
-			Symlink(fst.Tmp+"/etc/nixos", "/etc/nixos").
-			Symlink(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
-			Symlink(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
-			Symlink(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
-			Symlink(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
-			Symlink(fst.Tmp+"/etc/os-release", "/etc/os-release").
-			Symlink(fst.Tmp+"/etc/pam", "/etc/pam").
-			Symlink(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
-			Symlink(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
-			Symlink(fst.Tmp+"/etc/pki", "/etc/pki").
-			Symlink(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
-			Symlink(fst.Tmp+"/etc/profile", "/etc/profile").
-			Symlink(fst.Tmp+"/etc/protocols", "/etc/protocols").
-			Symlink(fst.Tmp+"/etc/qemu", "/etc/qemu").
-			Symlink(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
-			Symlink(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
-			Symlink(fst.Tmp+"/etc/rpc", "/etc/rpc").
-			Symlink(fst.Tmp+"/etc/samba", "/etc/samba").
-			Symlink(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
-			Symlink(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
-			Symlink(fst.Tmp+"/etc/services", "/etc/services").
-			Symlink(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
-			Symlink(fst.Tmp+"/etc/shadow", "/etc/shadow").
-			Symlink(fst.Tmp+"/etc/shells", "/etc/shells").
-			Symlink(fst.Tmp+"/etc/ssh", "/etc/ssh").
-			Symlink(fst.Tmp+"/etc/ssl", "/etc/ssl").
-			Symlink(fst.Tmp+"/etc/static", "/etc/static").
-			Symlink(fst.Tmp+"/etc/subgid", "/etc/subgid").
-			Symlink(fst.Tmp+"/etc/subuid", "/etc/subuid").
-			Symlink(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
-			Symlink(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
-			Symlink(fst.Tmp+"/etc/systemd", "/etc/systemd").
-			Symlink(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
-			Symlink(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
-			Symlink(fst.Tmp+"/etc/udev", "/etc/udev").
-			Symlink(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
-			Symlink(fst.Tmp+"/etc/UPower", "/etc/UPower").
-			Symlink(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
-			Symlink(fst.Tmp+"/etc/X11", "/etc/X11").
-			Symlink(fst.Tmp+"/etc/zfs", "/etc/zfs").
-			Symlink(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
-			Symlink(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
-			Symlink(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
-			Symlink(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
-			Symlink(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/65534", 8388608).
-			Bind("/tmp/fortify.1971/tmpdir/9", "/tmp", false, true).
-			Bind("/home/chronos", "/home/chronos", false, true).
-			CopyBind("/etc/passwd", []byte("chronos:x:65534:65534:Fortify:/home/chronos:/run/current-system/sw/bin/zsh\n")).
-			CopyBind("/etc/group", []byte("fortify:x:65534:\n")).
-			Bind("/tmp/fortify.1971/wayland/ebf083d1b175911782d413369b64ce7c", "/run/user/65534/wayland-0").
-			Bind("/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c/pulse", "/run/user/65534/pulse/native").
-			CopyBind(fst.Tmp+"/pulse-cookie", nil).
-			Bind("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/bus", "/run/user/65534/bus").
-			Bind("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/system_bus_socket", "/run/dbus/system_bus_socket").
-			Tmpfs("/var/run/nscd", 8192).
-			Bind("/run/wrappers/bin/fortify", "/.fortify/sbin/fortify").
-			Symlink("fortify", "/.fortify/sbin/init"),
+			Ops: new(sandbox.Ops).
+				Proc("/proc").
+				Tmpfs(fst.Tmp, 4096, 0755).
+				Dev("/dev").Mqueue("/dev/mqueue").
+				Bind("/bin", "/bin", sandbox.BindWritable).
+				Bind("/boot", "/boot", sandbox.BindWritable).
+				Bind("/home", "/home", sandbox.BindWritable).
+				Bind("/lib", "/lib", sandbox.BindWritable).
+				Bind("/lib64", "/lib64", sandbox.BindWritable).
+				Bind("/nix", "/nix", sandbox.BindWritable).
+				Bind("/root", "/root", sandbox.BindWritable).
+				Bind("/run", "/run", sandbox.BindWritable).
+				Bind("/srv", "/srv", sandbox.BindWritable).
+				Bind("/sys", "/sys", sandbox.BindWritable).
+				Bind("/usr", "/usr", sandbox.BindWritable).
+				Bind("/var", "/var", sandbox.BindWritable).
+				Bind("/dev/dri", "/dev/dri", sandbox.BindWritable|sandbox.BindDevice|sandbox.BindOptional).
+				Bind("/dev/kvm", "/dev/kvm", sandbox.BindWritable|sandbox.BindDevice|sandbox.BindOptional).
+				Tmpfs("/run/user/1971", 8192, 0755).
+				Tmpfs("/run/dbus", 8192, 0755).
+				Bind("/etc", fst.Tmp+"/etc", 0).
+				Link(fst.Tmp+"/etc/alsa", "/etc/alsa").
+				Link(fst.Tmp+"/etc/bashrc", "/etc/bashrc").
+				Link(fst.Tmp+"/etc/binfmt.d", "/etc/binfmt.d").
+				Link(fst.Tmp+"/etc/dbus-1", "/etc/dbus-1").
+				Link(fst.Tmp+"/etc/default", "/etc/default").
+				Link(fst.Tmp+"/etc/ethertypes", "/etc/ethertypes").
+				Link(fst.Tmp+"/etc/fonts", "/etc/fonts").
+				Link(fst.Tmp+"/etc/fstab", "/etc/fstab").
+				Link(fst.Tmp+"/etc/fuse.conf", "/etc/fuse.conf").
+				Link(fst.Tmp+"/etc/host.conf", "/etc/host.conf").
+				Link(fst.Tmp+"/etc/hostid", "/etc/hostid").
+				Link(fst.Tmp+"/etc/hostname", "/etc/hostname").
+				Link(fst.Tmp+"/etc/hostname.CHECKSUM", "/etc/hostname.CHECKSUM").
+				Link(fst.Tmp+"/etc/hosts", "/etc/hosts").
+				Link(fst.Tmp+"/etc/inputrc", "/etc/inputrc").
+				Link(fst.Tmp+"/etc/ipsec.d", "/etc/ipsec.d").
+				Link(fst.Tmp+"/etc/issue", "/etc/issue").
+				Link(fst.Tmp+"/etc/kbd", "/etc/kbd").
+				Link(fst.Tmp+"/etc/libblockdev", "/etc/libblockdev").
+				Link(fst.Tmp+"/etc/locale.conf", "/etc/locale.conf").
+				Link(fst.Tmp+"/etc/localtime", "/etc/localtime").
+				Link(fst.Tmp+"/etc/login.defs", "/etc/login.defs").
+				Link(fst.Tmp+"/etc/lsb-release", "/etc/lsb-release").
+				Link(fst.Tmp+"/etc/lvm", "/etc/lvm").
+				Link(fst.Tmp+"/etc/machine-id", "/etc/machine-id").
+				Link(fst.Tmp+"/etc/man_db.conf", "/etc/man_db.conf").
+				Link(fst.Tmp+"/etc/modprobe.d", "/etc/modprobe.d").
+				Link(fst.Tmp+"/etc/modules-load.d", "/etc/modules-load.d").
+				Link("/proc/mounts", "/etc/mtab").
+				Link(fst.Tmp+"/etc/nanorc", "/etc/nanorc").
+				Link(fst.Tmp+"/etc/netgroup", "/etc/netgroup").
+				Link(fst.Tmp+"/etc/NetworkManager", "/etc/NetworkManager").
+				Link(fst.Tmp+"/etc/nix", "/etc/nix").
+				Link(fst.Tmp+"/etc/nixos", "/etc/nixos").
+				Link(fst.Tmp+"/etc/NIXOS", "/etc/NIXOS").
+				Link(fst.Tmp+"/etc/nscd.conf", "/etc/nscd.conf").
+				Link(fst.Tmp+"/etc/nsswitch.conf", "/etc/nsswitch.conf").
+				Link(fst.Tmp+"/etc/opensnitchd", "/etc/opensnitchd").
+				Link(fst.Tmp+"/etc/os-release", "/etc/os-release").
+				Link(fst.Tmp+"/etc/pam", "/etc/pam").
+				Link(fst.Tmp+"/etc/pam.d", "/etc/pam.d").
+				Link(fst.Tmp+"/etc/pipewire", "/etc/pipewire").
+				Link(fst.Tmp+"/etc/pki", "/etc/pki").
+				Link(fst.Tmp+"/etc/polkit-1", "/etc/polkit-1").
+				Link(fst.Tmp+"/etc/profile", "/etc/profile").
+				Link(fst.Tmp+"/etc/protocols", "/etc/protocols").
+				Link(fst.Tmp+"/etc/qemu", "/etc/qemu").
+				Link(fst.Tmp+"/etc/resolv.conf", "/etc/resolv.conf").
+				Link(fst.Tmp+"/etc/resolvconf.conf", "/etc/resolvconf.conf").
+				Link(fst.Tmp+"/etc/rpc", "/etc/rpc").
+				Link(fst.Tmp+"/etc/samba", "/etc/samba").
+				Link(fst.Tmp+"/etc/sddm.conf", "/etc/sddm.conf").
+				Link(fst.Tmp+"/etc/secureboot", "/etc/secureboot").
+				Link(fst.Tmp+"/etc/services", "/etc/services").
+				Link(fst.Tmp+"/etc/set-environment", "/etc/set-environment").
+				Link(fst.Tmp+"/etc/shadow", "/etc/shadow").
+				Link(fst.Tmp+"/etc/shells", "/etc/shells").
+				Link(fst.Tmp+"/etc/ssh", "/etc/ssh").
+				Link(fst.Tmp+"/etc/ssl", "/etc/ssl").
+				Link(fst.Tmp+"/etc/static", "/etc/static").
+				Link(fst.Tmp+"/etc/subgid", "/etc/subgid").
+				Link(fst.Tmp+"/etc/subuid", "/etc/subuid").
+				Link(fst.Tmp+"/etc/sudoers", "/etc/sudoers").
+				Link(fst.Tmp+"/etc/sysctl.d", "/etc/sysctl.d").
+				Link(fst.Tmp+"/etc/systemd", "/etc/systemd").
+				Link(fst.Tmp+"/etc/terminfo", "/etc/terminfo").
+				Link(fst.Tmp+"/etc/tmpfiles.d", "/etc/tmpfiles.d").
+				Link(fst.Tmp+"/etc/udev", "/etc/udev").
+				Link(fst.Tmp+"/etc/udisks2", "/etc/udisks2").
+				Link(fst.Tmp+"/etc/UPower", "/etc/UPower").
+				Link(fst.Tmp+"/etc/vconsole.conf", "/etc/vconsole.conf").
+				Link(fst.Tmp+"/etc/X11", "/etc/X11").
+				Link(fst.Tmp+"/etc/zfs", "/etc/zfs").
+				Link(fst.Tmp+"/etc/zinputrc", "/etc/zinputrc").
+				Link(fst.Tmp+"/etc/zoneinfo", "/etc/zoneinfo").
+				Link(fst.Tmp+"/etc/zprofile", "/etc/zprofile").
+				Link(fst.Tmp+"/etc/zshenv", "/etc/zshenv").
+				Link(fst.Tmp+"/etc/zshrc", "/etc/zshrc").
+				Tmpfs("/run/user", 4096, 0755).
+				Tmpfs("/run/user/65534", 8388608, 0700).
+				Bind("/tmp/fortify.1971/tmpdir/9", "/tmp", sandbox.BindWritable).
+				Bind("/home/chronos", "/home/chronos", sandbox.BindWritable).
+				Place("/etc/passwd", []byte("chronos:x:65534:65534:Fortify:/home/chronos:/run/current-system/sw/bin/zsh\n")).
+				Place("/etc/group", []byte("fortify:x:65534:\n")).
+				Bind("/tmp/fortify.1971/wayland/ebf083d1b175911782d413369b64ce7c", "/run/user/65534/wayland-0", 0).
+				Bind("/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c/pulse", "/run/user/65534/pulse/native", 0).
+				Place(fst.Tmp+"/pulse-cookie", nil).
+				Bind("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/bus", "/run/user/65534/bus", 0).
+				Bind("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/system_bus_socket", "/run/dbus/system_bus_socket", 0).
+				Tmpfs("/var/run/nscd", 8192, 0755),
+		},
 	},
 }

internal/app/app_stub_test.go

@@ -17,7 +17,8 @@ type stubNixOS struct {
 	usernameErr map[string]error
 }
 
-func (s *stubNixOS) Geteuid() int                             { return 1971 }
+func (s *stubNixOS) Getuid() int                              { return 1971 }
+func (s *stubNixOS) Getgid() int                              { return 100 }
 func (s *stubNixOS) TempDir() string                          { return "/tmp" }
 func (s *stubNixOS) MustExecutable() string                   { return "/run/wrappers/bin/fortify" }
 func (s *stubNixOS) Exit(code int)                            { panic("called exit on stub with code " + strconv.Itoa(code)) }
@@ -54,10 +55,8 @@ func (s *stubNixOS) LookPath(file string) (string, error) {
 	}
 
 	switch file {
-	case "sudo":
-		return "/run/wrappers/bin/sudo", nil
-	case "machinectl":
-		return "/home/ophestra/.nix-profile/bin/machinectl", nil
+	case "zsh":
+		return "/run/current-system/sw/bin/zsh", nil
 	default:
 		panic(fmt.Sprintf("attempted to look up unexpected executable %q", file))
 	}

internal/app/app_test.go

@@ -8,19 +8,19 @@ import (
 	"time"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/internal/app"
 	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
 type sealTestCase struct {
-	name      string
-	os        sys.State
-	config    *fst.Config
-	id        fst.ID
-	wantSys   *system.I
-	wantBwrap *bwrap.Config
+	name          string
+	os            sys.State
+	config        *fst.Config
+	id            fst.ID
+	wantSys       *system.I
+	wantContainer *sandbox.Params
 }
 
 func TestApp(t *testing.T) {
@@ -30,15 +30,15 @@ func TestApp(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			a := app.NewWithID(tc.id, tc.os)
 			var (
-				gotSys   *system.I
-				gotBwrap *bwrap.Config
+				gotSys       *system.I
+				gotContainer *sandbox.Params
 			)
 			if !t.Run("seal", func(t *testing.T) {
 				if sa, err := a.Seal(tc.config); err != nil {
 					t.Errorf("Seal: error = %v", err)
 					return
 				} else {
-					gotSys, gotBwrap = app.AppSystemBwrap(a, sa)
+					gotSys, gotContainer = app.AppIParams(a, sa)
 				}
 			}) {
 				return
@@ -51,10 +51,10 @@ func TestApp(t *testing.T) {
 				}
 			})
 
-			t.Run("compare bwrap", func(t *testing.T) {
-				if !reflect.DeepEqual(gotBwrap, tc.wantBwrap) {
-					t.Errorf("seal: bwrap =\n%s\n, want\n%s",
-						mustMarshal(gotBwrap), mustMarshal(tc.wantBwrap))
+			t.Run("compare params", func(t *testing.T) {
+				if !reflect.DeepEqual(gotContainer, tc.wantContainer) {
+					t.Errorf("seal: params =\n%s\n, want\n%s",
+						mustMarshal(gotContainer), mustMarshal(tc.wantContainer))
 				}
 			})
 		})

internal/app/export_test.go

@@ -2,8 +2,8 @@ package app
 
 import (
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
@@ -14,7 +14,7 @@ func NewWithID(id fst.ID, os sys.State) fst.App {
 	return a
 }
 
-func AppSystemBwrap(a fst.App, sa fst.SealedApp) (*system.I, *bwrap.Config) {
+func AppIParams(a fst.App, sa fst.SealedApp) (*system.I, *sandbox.Params) {
 	v := a.(*app)
 	seal := sa.(*outcome)
 	if v.outcome != seal || v.id != seal.id {

internal/app/init/early.go

@@ -1,18 +0,0 @@
-package init0
-
-import (
-	"os"
-	"path"
-
-	"git.gensokyo.uk/security/fortify/internal"
-)
-
-// used by the parent process
-
-// TryArgv0 calls [Main] if argv0 indicates the process is started from a file named "init".
-func TryArgv0() {
-	if len(os.Args) > 0 && path.Base(os.Args[0]) == "init" {
-		Main()
-		internal.Exit(0)
-	}
-}

internal/app/init/main.go

@@ -1,165 +0,0 @@
-package init0
-
-import (
-	"errors"
-	"log"
-	"os"
-	"os/exec"
-	"os/signal"
-	"syscall"
-	"time"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/internal"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-const (
-	// time to wait for linger processes after death of initial process
-	residualProcessTimeout = 5 * time.Second
-)
-
-// everything beyond this point runs within pid namespace
-// proceed with caution!
-
-func Main() {
-	// sharing stdout with shim
-	// USE WITH CAUTION
-	fmsg.Prepare("init")
-
-	// setting this prevents ptrace
-	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
-	}
-
-	if os.Getpid() != 1 {
-		log.Fatal("this process must run as pid 1")
-	}
-
-	// receive setup payload
-	var (
-		payload    Payload
-		closeSetup func() error
-	)
-	if f, err := proc.Receive(Env, &payload); err != nil {
-		if errors.Is(err, proc.ErrInvalid) {
-			log.Fatal("invalid config descriptor")
-		}
-		if errors.Is(err, proc.ErrNotSet) {
-			log.Fatal("FORTIFY_INIT not set")
-		}
-
-		log.Fatalf("cannot decode init setup payload: %v", err)
-	} else {
-		fmsg.Store(payload.Verbose)
-		closeSetup = f
-
-		// child does not need to see this
-		if err = os.Unsetenv(Env); err != nil {
-			log.Printf("cannot unset %s: %v", Env, err)
-			// not fatal
-		} else {
-			fmsg.Verbose("received configuration")
-		}
-	}
-
-	// die with parent
-	if err := internal.PR_SET_PDEATHSIG__SIGKILL(); err != nil {
-		log.Fatalf("prctl(PR_SET_PDEATHSIG, SIGKILL): %v", err)
-	}
-
-	cmd := exec.Command(payload.Argv0)
-	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
-	cmd.Args = payload.Argv
-	cmd.Env = os.Environ()
-
-	if err := cmd.Start(); err != nil {
-		log.Fatalf("cannot start %q: %v", payload.Argv0, err)
-	}
-	fmsg.Suspend()
-
-	// close setup pipe as setup is now complete
-	if err := closeSetup(); err != nil {
-		log.Println("cannot close setup pipe:", err)
-		// not fatal
-	}
-
-	sig := make(chan os.Signal, 2)
-	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
-
-	type winfo struct {
-		wpid    int
-		wstatus syscall.WaitStatus
-	}
-	info := make(chan winfo, 1)
-	done := make(chan struct{})
-
-	go func() {
-		var (
-			err     error
-			wpid    = -2
-			wstatus syscall.WaitStatus
-		)
-
-		// keep going until no child process is left
-		for wpid != -1 {
-			if err != nil {
-				break
-			}
-
-			if wpid != -2 {
-				info <- winfo{wpid, wstatus}
-			}
-
-			err = syscall.EINTR
-			for errors.Is(err, syscall.EINTR) {
-				wpid, err = syscall.Wait4(-1, &wstatus, 0, nil)
-			}
-		}
-		if !errors.Is(err, syscall.ECHILD) {
-			log.Println("unexpected wait4 response:", err)
-		}
-
-		close(done)
-	}()
-
-	// closed after residualProcessTimeout has elapsed after initial process death
-	timeout := make(chan struct{})
-
-	r := 2
-	for {
-		select {
-		case s := <-sig:
-			if fmsg.Resume() {
-				fmsg.Verbosef("terminating on %s after process start", s.String())
-			} else {
-				fmsg.Verbosef("terminating on %s", s.String())
-			}
-			internal.Exit(0)
-		case w := <-info:
-			if w.wpid == cmd.Process.Pid {
-				// initial process exited, output is most likely available again
-				fmsg.Resume()
-
-				switch {
-				case w.wstatus.Exited():
-					r = w.wstatus.ExitStatus()
-				case w.wstatus.Signaled():
-					r = 128 + int(w.wstatus.Signal())
-				default:
-					r = 255
-				}
-
-				go func() {
-					time.Sleep(residualProcessTimeout)
-					close(timeout)
-				}()
-			}
-		case <-done:
-			internal.Exit(r)
-		case <-timeout:
-			log.Println("timeout exceeded waiting for lingering processes")
-			internal.Exit(r)
-		}
-	}
-}

internal/app/init/payload.go

@@ -1,13 +0,0 @@
-package init0
-
-const Env = "FORTIFY_INIT"
-
-type Payload struct {
-	// target full exec path
-	Argv0 string
-	// child full argv
-	Argv []string
-
-	// verbosity pass through
-	Verbose bool
-}

internal/app/process.go

@@ -3,17 +3,12 @@ package app
 import (
 	"context"
 	"errors"
-	"fmt"
 	"log"
 	"os/exec"
-	"path/filepath"
-	"strings"
 	"time"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper"
 	"git.gensokyo.uk/security/fortify/internal"
-	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/state"
 	"git.gensokyo.uk/security/fortify/system"
@@ -21,7 +16,7 @@ import (
 
 const shimSetupTimeout = 5 * time.Second
 
-func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
+func (seal *outcome) Run(rs *fst.RunState) error {
 	if !seal.f.CompareAndSwap(false, true) {
 		// run does much more than just starting a process; calling it twice, even if the first call fails, will result
 		// in inconsistent state that is impossible to clean up; return here to limit damage and hopefully give the
@@ -37,33 +32,11 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 	fmsg.Verbosef("version %s", internal.Version())
 	fmsg.Verbosef("setuid helper at %s", internal.MustFsuPath())
 
-	/*
-		resolve exec paths
-	*/
-
-	shimExec := [2]string{helper.BubblewrapName}
-	if len(seal.command) > 0 {
-		shimExec[1] = seal.command[0]
-	}
-	for i, n := range shimExec {
-		if len(n) == 0 {
-			continue
-		}
-		if filepath.Base(n) == n {
-			if s, err := exec.LookPath(n); err == nil {
-				shimExec[i] = s
-			} else {
-				return fmsg.WrapError(err,
-					fmt.Sprintf("executable file %q not found in $PATH", n))
-			}
-		}
-	}
-
 	/*
 		prepare/revert os state
 	*/
 
-	if err := seal.sys.Commit(ctx); err != nil {
+	if err := seal.sys.Commit(seal.ctx); err != nil {
 		return err
 	}
 	store := state.NewMulti(seal.runDirPath)
@@ -79,17 +52,16 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 					revert app setup transaction
 				*/
 
-				rt, ec := new(system.Enablements), new(system.Criteria)
-				ec.Enablements = new(system.Enablements)
-				ec.Set(system.Process)
+				var rt system.Enablement
+				ec := system.Process
 				if states, err := c.Load(); err != nil {
 					// revert per-process state here to limit damage
 					storeErr.OpErr = err
-					return seal.sys.Revert(ec)
+					return seal.sys.Revert((*system.Criteria)(&ec))
 				} else {
 					if l := len(states); l == 0 {
 						fmsg.Verbose("no other launchers active, will clean up globals")
-						ec.Set(system.User)
+						ec |= system.User
 					} else {
 						fmsg.Verbosef("found %d active launchers, cleaning up without globals", l)
 					}
@@ -97,31 +69,20 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 					// accumulate enablements of remaining launchers
 					for i, s := range states {
 						if s.Config != nil {
-							*rt |= s.Config.Confinement.Enablements
+							rt |= s.Config.Confinement.Enablements
 						} else {
 							log.Printf("state entry %d does not contain config", i)
 						}
 					}
 				}
-				// invert accumulated enablements for cleanup
-				for i := system.Enablement(0); i < system.Enablement(system.ELen); i++ {
-					if !rt.Has(i) {
-						ec.Set(i)
-					}
-				}
+				ec |= rt ^ (system.EWayland | system.EX11 | system.EDBus | system.EPulse)
 				if fmsg.Load() {
-					labels := make([]string, 0, system.ELen+1)
-					for i := system.Enablement(0); i < system.Enablement(system.ELen+2); i++ {
-						if ec.Has(i) {
-							labels = append(labels, system.TypeString(i))
-						}
-					}
-					if len(labels) > 0 {
-						fmsg.Verbose("reverting operations type", strings.Join(labels, ", "))
+					if ec > 0 {
+						fmsg.Verbose("reverting operations type", system.TypeString(ec))
 					}
 				}
 
-				return seal.sys.Revert(ec)
+				return seal.sys.Revert((*system.Criteria)(&ec))
 			}()
 		})
 		storeErr.save([]error{revertErr, store.Close()})
@@ -133,11 +94,10 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 	*/
 
 	waitErr := make(chan error, 1)
-	cmd := new(shim.Shim)
+	cmd := new(shimProcess)
 	if startTime, err := cmd.Start(
 		seal.user.aid.String(),
 		seal.user.supp,
-		seal.bwrapSync,
 	); err != nil {
 		return err
 	} else {
@@ -145,7 +105,7 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 		rs.Time = startTime
 	}
 
-	c, cancel := context.WithTimeout(ctx, shimSetupTimeout)
+	ctx, cancel := context.WithTimeout(seal.ctx, shimSetupTimeout)
 	defer cancel()
 
 	go func() {
@@ -154,11 +114,9 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 		cancel()
 	}()
 
-	if err := cmd.Serve(c, &shim.Payload{
-		Argv:  seal.command,
-		Exec:  shimExec,
-		Bwrap: seal.container,
-		Home:  seal.user.data,
+	if err := cmd.Serve(ctx, &shimParams{
+		Container: seal.container,
+		Home:      seal.user.data,
 
 		Verbose: fmsg.Load(),
 	}); err != nil {
@@ -199,18 +157,22 @@ func (seal *outcome) Run(ctx context.Context, rs *fst.RunState) error {
 	// this is reached when a fault makes an already running shim impossible to continue execution
 	// however a kill signal could not be delivered (should actually always happen like that since fsu)
 	// the effects of this is similar to the alternative exit path and ensures shim death
-	case err := <-cmd.WaitFallback():
+	case err := <-cmd.Fallback():
 		rs.ExitCode = 255
 		log.Printf("cannot terminate shim on faulted setup: %v", err)
 
 	// alternative exit path relying on shim behaviour on monitor process exit
-	case <-ctx.Done():
+	case <-seal.ctx.Done():
 		fmsg.Verbose("alternative exit path selected")
 	}
 
 	fmsg.Resume()
+	if seal.sync != nil {
+		if err := seal.sync.Close(); err != nil {
+			log.Printf("cannot close wayland security context: %v", err)
+		}
+	}
 	if seal.dbusMsg != nil {
-		// dump dbus message buffer
 		seal.dbusMsg()
 	}
 

internal/app/seal.go

@@ -2,26 +2,30 @@ package app
 
 import (
 	"bytes"
+	"context"
 	"encoding/gob"
 	"errors"
 	"fmt"
 	"io"
 	"io/fs"
+	"maps"
 	"os"
 	"path"
 	"regexp"
+	"slices"
 	"strings"
 	"sync/atomic"
+	"syscall"
 
 	"git.gensokyo.uk/security/fortify/acl"
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/sandbox/wl"
 	"git.gensokyo.uk/security/fortify/system"
-	"git.gensokyo.uk/security/fortify/wl"
 )
 
 const (
@@ -65,19 +69,19 @@ type outcome struct {
 	// copied from [sys.State] response
 	runDirPath string
 
-	// passed through from [fst.Config]
-	command []string
-
 	// initial [fst.Config] gob stream for state data;
-	// this is prepared ahead of time as config is mutated during seal creation
+	// this is prepared ahead of time as config is clobbered during seal creation
 	ct io.WriterTo
 	// dump dbus proxy message buffer
 	dbusMsg func()
 
-	user      fsuUser
-	sys       *system.I
-	container *bwrap.Config
-	bwrapSync *os.File
+	user fsuUser
+	sys  *system.I
+	ctx  context.Context
+
+	container *sandbox.Params
+	env       map[string]string
+	sync      *os.File
 
 	f atomic.Bool
 }
@@ -100,7 +104,17 @@ type fsuUser struct {
 	username string
 }
 
-func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
+func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Config) error {
+	if seal.ctx != nil {
+		panic("finalise called twice")
+	}
+	seal.ctx = ctx
+
+	shellPath := "/bin/sh"
+	if s, ok := sys.LookupEnv(shell); ok && path.IsAbs(s) {
+		shellPath = s
+	}
+
 	{
 		// encode initial configuration for state tracking
 		ct := new(bytes.Buffer)
@@ -111,9 +125,6 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		seal.ct = ct
 	}
 
-	// pass through command slice; this value is never touched in the main process
-	seal.command = config.Command
-
 	// allowed aid range 0 to 9999, this is checked again in fsu
 	if config.Confinement.AppID < 0 || config.Confinement.AppID > 9999 {
 		return fmsg.WrapError(ErrUser,
@@ -167,12 +178,24 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 	if config.Confinement.Sandbox == nil {
 		fmsg.Verbose("sandbox configuration not supplied, PROCEED WITH CAUTION")
 
+		// fsu clears the environment so resolve paths early
+		if !path.IsAbs(config.Path) {
+			if len(config.Args) > 0 {
+				if p, err := sys.LookPath(config.Args[0]); err != nil {
+					return fmsg.WrapError(err, err.Error())
+				} else {
+					config.Path = p
+				}
+			} else {
+				config.Path = shellPath
+			}
+		}
+
 		conf := &fst.SandboxConfig{
-			UserNS:       true,
-			Net:          true,
-			Syscall:      new(bwrap.SyscallPolicy),
-			NoNewSession: true,
-			AutoEtc:      true,
+			Userns:  true,
+			Net:     true,
+			Tty:     true,
+			AutoEtc: true,
 		}
 		// bind entries in /
 		if d, err := sys.ReadDir("/"); err != nil {
@@ -198,10 +221,10 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		// hide nscd from sandbox if present
 		nscd := "/var/run/nscd"
 		if _, err := sys.Stat(nscd); !errors.Is(err, fs.ErrNotExist) {
-			conf.Override = append(conf.Override, nscd)
+			conf.Cover = append(conf.Cover, nscd)
 		}
 		// bind GPU stuff
-		if config.Confinement.Enablements.Has(system.EX11) || config.Confinement.Enablements.Has(system.EWayland) {
+		if config.Confinement.Enablements&(system.EX11|system.EWayland) != 0 {
 			conf.Filesystem = append(conf.Filesystem, &fst.FilesystemConfig{Src: "/dev/dri", Device: true})
 		}
 		// opportunistically bind kvm
@@ -210,17 +233,29 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		config.Confinement.Sandbox = conf
 	}
 
-	var mapuid *stringPair[int]
+	var mapuid, mapgid *stringPair[int]
 	{
-		var uid int
+		var uid, gid int
 		var err error
-		seal.container, err = config.Confinement.Sandbox.Bwrap(sys, &uid)
+		seal.container, seal.env, err = config.Confinement.Sandbox.ToContainer(sys, &uid, &gid)
 		if err != nil {
-			return err
+			return fmsg.WrapErrorSuffix(err,
+				"cannot initialise container configuration:")
 		}
+		if !path.IsAbs(config.Path) {
+			return fmsg.WrapError(syscall.EINVAL,
+				"invalid program path")
+		}
+		if len(config.Args) == 0 {
+			config.Args = []string{config.Path}
+		}
+		seal.container.Path = config.Path
+		seal.container.Args = config.Args
+
 		mapuid = newInt(uid)
-		if seal.container.SetEnv == nil {
-			seal.container.SetEnv = make(map[string]string)
+		mapgid = newInt(gid)
+		if seal.env == nil {
+			seal.env = make(map[string]string)
 		}
 	}
 
@@ -231,10 +266,6 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 	sc := sys.Paths()
 	seal.runDirPath = sc.RunDirPath
 	seal.sys = system.New(seal.user.uid.unwrap())
-	seal.sys.IsVerbose = fmsg.Load
-	seal.sys.Verbose = fmsg.Verbose
-	seal.sys.Verbosef = fmsg.Verbosef
-	seal.sys.WrapErr = fmsg.WrapError
 
 	/*
 		Work directories
@@ -259,35 +290,27 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 
 	// inner XDG_RUNTIME_DIR default formatting of `/run/user/%d` as post-fsu user
 	innerRuntimeDir := path.Join("/run/user", mapuid.String())
-	seal.container.Tmpfs("/run/user", 1*1024*1024)
-	seal.container.Tmpfs(innerRuntimeDir, 8*1024*1024)
-	seal.container.SetEnv[xdgRuntimeDir] = innerRuntimeDir
-	seal.container.SetEnv[xdgSessionClass] = "user"
-	seal.container.SetEnv[xdgSessionType] = "tty"
+	seal.container.Tmpfs("/run/user", 1<<12, 0755)
+	seal.container.Tmpfs(innerRuntimeDir, 1<<23, 0700)
+	seal.env[xdgRuntimeDir] = innerRuntimeDir
+	seal.env[xdgSessionClass] = "user"
+	seal.env[xdgSessionType] = "tty"
 
 	// outer path for inner /tmp
 	{
 		tmpdir := path.Join(sc.SharePath, "tmpdir")
 		seal.sys.Ensure(tmpdir, 0700)
 		seal.sys.UpdatePermType(system.User, tmpdir, acl.Execute)
-		tmpdirProc := path.Join(tmpdir, seal.user.aid.String())
-		seal.sys.Ensure(tmpdirProc, 01700)
-		seal.sys.UpdatePermType(system.User, tmpdirProc, acl.Read, acl.Write, acl.Execute)
-		seal.container.Bind(tmpdirProc, "/tmp", false, true)
+		tmpdirInst := path.Join(tmpdir, seal.user.aid.String())
+		seal.sys.Ensure(tmpdirInst, 01700)
+		seal.sys.UpdatePermType(system.User, tmpdirInst, acl.Read, acl.Write, acl.Execute)
+		seal.container.Bind(tmpdirInst, "/tmp", sandbox.BindWritable)
 	}
 
 	/*
 		Passwd database
 	*/
 
-	// look up shell
-	sh := "/bin/sh"
-	if s, ok := sys.LookupEnv(shell); ok {
-		seal.container.SetEnv[shell] = s
-		sh = s
-	}
-
-	// bind home directory
 	homeDir := "/var/empty"
 	if seal.user.home != "" {
 		homeDir = seal.user.home
@@ -296,28 +319,26 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 	if seal.user.username != "" {
 		username = seal.user.username
 	}
-	seal.container.Bind(seal.user.data, homeDir, false, true)
-	seal.container.Chdir = homeDir
-	seal.container.SetEnv["HOME"] = homeDir
-	seal.container.SetEnv["USER"] = username
+	seal.container.Bind(seal.user.data, homeDir, sandbox.BindWritable)
+	seal.container.Dir = homeDir
+	seal.env["HOME"] = homeDir
+	seal.env["USER"] = username
 
-	// generate /etc/passwd and /etc/group
-	seal.container.CopyBind("/etc/passwd",
-		[]byte(username+":x:"+mapuid.String()+":"+mapuid.String()+":Fortify:"+homeDir+":"+sh+"\n"))
-	seal.container.CopyBind("/etc/group",
-		[]byte("fortify:x:"+mapuid.String()+":\n"))
+	seal.container.Place("/etc/passwd",
+		[]byte(username+":x:"+mapuid.String()+":"+mapgid.String()+":Fortify:"+homeDir+":"+shellPath+"\n"))
+	seal.container.Place("/etc/group",
+		[]byte("fortify:x:"+mapgid.String()+":\n"))
 
 	/*
 		Display servers
 	*/
 
-	// pass $TERM to launcher
+	// pass $TERM for proper terminal I/O in shell
 	if t, ok := sys.LookupEnv(term); ok {
-		seal.container.SetEnv[term] = t
+		seal.env[term] = t
 	}
 
-	// set up wayland
-	if config.Confinement.Enablements.Has(system.EWayland) {
+	if config.Confinement.Enablements&system.EWayland != 0 {
 		// outer wayland socket (usually `/run/user/%d/wayland-%d`)
 		var socketPath string
 		if name, ok := sys.LookupEnv(wl.WaylandDisplay); !ok {
@@ -330,7 +351,7 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		}
 
 		innerPath := path.Join(innerRuntimeDir, wl.FallbackName)
-		seal.container.SetEnv[wl.WaylandDisplay] = wl.FallbackName
+		seal.env[wl.WaylandDisplay] = wl.FallbackName
 
 		if !config.Confinement.Sandbox.DirectWayland { // set up security-context-v1
 			socketDir := path.Join(sc.SharePath, "wayland")
@@ -341,25 +362,23 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 				// use instance ID in case app id is not set
 				appID = "uk.gensokyo.fortify." + seal.id.String()
 			}
-			seal.sys.Wayland(&seal.bwrapSync, outerPath, socketPath, appID, seal.id.String())
-			seal.container.Bind(outerPath, innerPath)
+			seal.sys.Wayland(&seal.sync, outerPath, socketPath, appID, seal.id.String())
+			seal.container.Bind(outerPath, innerPath, 0)
 		} else { // bind mount wayland socket (insecure)
 			fmsg.Verbose("direct wayland access, PROCEED WITH CAUTION")
-			seal.container.Bind(socketPath, innerPath)
+			seal.container.Bind(socketPath, innerPath, 0)
 			seal.sys.UpdatePermType(system.EWayland, socketPath, acl.Read, acl.Write, acl.Execute)
 		}
 	}
 
-	// set up X11
-	if config.Confinement.Enablements.Has(system.EX11) {
-		// discover X11 and grant user permission via the `ChangeHosts` command
+	if config.Confinement.Enablements&system.EX11 != 0 {
 		if d, ok := sys.LookupEnv(display); !ok {
 			return fmsg.WrapError(ErrXDisplay,
 				"DISPLAY is not set")
 		} else {
 			seal.sys.ChangeHosts("#" + seal.user.uid.String())
-			seal.container.SetEnv[display] = d
-			seal.container.Bind("/tmp/.X11-unix", "/tmp/.X11-unix")
+			seal.env[display] = d
+			seal.container.Bind("/tmp/.X11-unix", "/tmp/.X11-unix", 0)
 		}
 	}
 
@@ -367,7 +386,7 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		PulseAudio server and authentication
 	*/
 
-	if config.Confinement.Enablements.Has(system.EPulse) {
+	if config.Confinement.Enablements&system.EPulse != 0 {
 		// PulseAudio runtime directory (usually `/run/user/%d/pulse`)
 		pulseRuntimeDir := path.Join(sc.RuntimePath, "pulse")
 		// PulseAudio socket (usually `/run/user/%d/pulse/native`)
@@ -400,8 +419,8 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		innerPulseRuntimeDir := path.Join(sharePathLocal, "pulse")
 		innerPulseSocket := path.Join(innerRuntimeDir, "pulse", "native")
 		seal.sys.Link(pulseSocket, innerPulseRuntimeDir)
-		seal.container.Bind(innerPulseRuntimeDir, innerPulseSocket)
-		seal.container.SetEnv[pulseServer] = "unix:" + innerPulseSocket
+		seal.container.Bind(innerPulseRuntimeDir, innerPulseSocket, 0)
+		seal.env[pulseServer] = "unix:" + innerPulseSocket
 
 		// publish current user's pulse cookie for target user
 		if src, err := discoverPulseCookie(sys); err != nil {
@@ -409,9 +428,9 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 			fmsg.Verbose(strings.TrimSpace(err.(*fmsg.BaseError).Message()))
 		} else {
 			innerDst := fst.Tmp + "/pulse-cookie"
-			seal.container.SetEnv[pulseCookie] = innerDst
-			payload := new([]byte)
-			seal.container.CopyBindRef(innerDst, &payload)
+			seal.env[pulseCookie] = innerDst
+			var payload *[]byte
+			seal.container.PlaceP(innerDst, &payload)
 			seal.sys.CopyFile(payload, src, 256, 256)
 		}
 	}
@@ -420,7 +439,7 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		D-Bus proxy
 	*/
 
-	if config.Confinement.Enablements.Has(system.EDBus) {
+	if config.Confinement.Enablements&system.EDBus != 0 {
 		// ensure dbus session bus defaults
 		if config.Confinement.SessionBus == nil {
 			config.Confinement.SessionBus = dbus.NewConfig(config.ID, true, true)
@@ -441,13 +460,13 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 
 		// share proxy sockets
 		sessionInner := path.Join(innerRuntimeDir, "bus")
-		seal.container.SetEnv[dbusSessionBusAddress] = "unix:path=" + sessionInner
-		seal.container.Bind(sessionPath, sessionInner)
+		seal.env[dbusSessionBusAddress] = "unix:path=" + sessionInner
+		seal.container.Bind(sessionPath, sessionInner, 0)
 		seal.sys.UpdatePerm(sessionPath, acl.Read, acl.Write)
 		if config.Confinement.SystemBus != nil {
 			systemInner := "/run/dbus/system_bus_socket"
-			seal.container.SetEnv[dbusSystemBusAddress] = "unix:path=" + systemInner
-			seal.container.Bind(systemPath, systemInner)
+			seal.env[dbusSystemBusAddress] = "unix:path=" + systemInner
+			seal.container.Bind(systemPath, systemInner, 0)
 			seal.sys.UpdatePerm(systemPath, acl.Read, acl.Write)
 		}
 	}
@@ -456,9 +475,8 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		Miscellaneous
 	*/
 
-	// queue overriding tmpfs at the end of seal.container.Filesystem
-	for _, dest := range config.Confinement.Sandbox.Override {
-		seal.container.Tmpfs(dest, 8*1024)
+	for _, dest := range config.Confinement.Sandbox.Cover {
+		seal.container.Tmpfs(dest, 1<<13, 0755)
 	}
 
 	// append ExtraPerms last
@@ -484,12 +502,13 @@ func (seal *outcome) finalise(sys sys.State, config *fst.Config) error {
 		seal.sys.UpdatePermType(system.User, p.Path, perms...)
 	}
 
-	// mount fortify in sandbox for init
-	seal.container.Bind(sys.MustExecutable(), path.Join(fst.Tmp, "sbin/fortify"))
-	seal.container.Symlink("fortify", path.Join(fst.Tmp, "sbin/init"))
+	// flatten and sort env for deterministic behaviour
+	seal.container.Env = make([]string, 0, len(seal.env))
+	maps.All(seal.env)(func(k string, v string) bool { seal.container.Env = append(seal.container.Env, k+"="+v); return true })
+	slices.Sort(seal.container.Env)
 
-	fmsg.Verbosef("created application seal for uid %s (%s) groups: %v, command: %s",
-		seal.user.uid, seal.user.username, config.Confinement.Groups, config.Command)
+	fmsg.Verbosef("created application seal for uid %s (%s) groups: %v, argv: %s",
+		seal.user.uid, seal.user.username, config.Confinement.Groups, seal.container.Args)
 
 	return nil
 }

internal/app/shim.go

@@ -0,0 +1,212 @@
+package app
+
+import (
+	"context"
+	"encoding/gob"
+	"errors"
+	"log"
+	"os"
+	"os/exec"
+	"os/signal"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+
+	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/sandbox"
+)
+
+const shimEnv = "FORTIFY_SHIM"
+
+type shimParams struct {
+	// finalised container params
+	Container *sandbox.Params
+	// path to outer home directory
+	Home string
+
+	// verbosity pass through
+	Verbose bool
+}
+
+// ShimMain is the main function of the shim process and runs as the unconstrained target user.
+func ShimMain() {
+	fmsg.Prepare("shim")
+
+	if err := sandbox.SetDumpable(sandbox.SUID_DUMP_DISABLE); err != nil {
+		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
+	}
+
+	var (
+		params     shimParams
+		closeSetup func() error
+	)
+	if f, err := sandbox.Receive(shimEnv, &params, nil); err != nil {
+		if errors.Is(err, sandbox.ErrInvalid) {
+			log.Fatal("invalid config descriptor")
+		}
+		if errors.Is(err, sandbox.ErrNotSet) {
+			log.Fatal("FORTIFY_SHIM not set")
+		}
+
+		log.Fatalf("cannot receive shim setup params: %v", err)
+	} else {
+		internal.InstallFmsg(params.Verbose)
+		closeSetup = f
+	}
+
+	if params.Container == nil || params.Container.Ops == nil {
+		log.Fatal("invalid container params")
+	}
+
+	// close setup socket
+	if err := closeSetup(); err != nil {
+		log.Printf("cannot close setup pipe: %v", err)
+		// not fatal
+	}
+
+	// ensure home directory as target user
+	if s, err := os.Stat(params.Home); err != nil {
+		if os.IsNotExist(err) {
+			if err = os.Mkdir(params.Home, 0700); err != nil {
+				log.Fatalf("cannot create home directory: %v", err)
+			}
+		} else {
+			log.Fatalf("cannot access home directory: %v", err)
+		}
+
+		// home directory is created, proceed
+	} else if !s.IsDir() {
+		log.Fatalf("path %q is not a directory", params.Home)
+	}
+
+	var name string
+	if len(params.Container.Args) > 0 {
+		name = params.Container.Args[0]
+	}
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop() // unreachable
+	container := sandbox.New(ctx, name)
+	container.Params = *params.Container
+	container.Stdin, container.Stdout, container.Stderr = os.Stdin, os.Stdout, os.Stderr
+	container.Cancel = func(cmd *exec.Cmd) error { return cmd.Process.Signal(os.Interrupt) }
+	container.WaitDelay = 2 * time.Second
+
+	if err := container.Start(); err != nil {
+		fmsg.PrintBaseError(err, "cannot start container:")
+		os.Exit(1)
+	}
+	if err := container.Serve(); err != nil {
+		fmsg.PrintBaseError(err, "cannot configure container:")
+	}
+	if err := container.Wait(); err != nil {
+		var exitError *exec.ExitError
+		if !errors.As(err, &exitError) {
+			if errors.Is(err, context.Canceled) {
+				os.Exit(2)
+			}
+			log.Printf("wait: %v", err)
+			os.Exit(127)
+		}
+		os.Exit(exitError.ExitCode())
+	}
+}
+
+type shimProcess struct {
+	// user switcher process
+	cmd *exec.Cmd
+	// fallback exit notifier with error returned killing the process
+	killFallback chan error
+	// monitor to shim encoder
+	encoder *gob.Encoder
+}
+
+func (s *shimProcess) Unwrap() *exec.Cmd    { return s.cmd }
+func (s *shimProcess) Fallback() chan error { return s.killFallback }
+
+func (s *shimProcess) String() string {
+	if s.cmd == nil {
+		return "(unused shim manager)"
+	}
+	return s.cmd.String()
+}
+
+func (s *shimProcess) Start(
+	aid string,
+	supp []string,
+) (*time.Time, error) {
+	// prepare user switcher invocation
+	fsuPath := internal.MustFsuPath()
+	s.cmd = exec.Command(fsuPath)
+
+	// pass shim setup pipe
+	if fd, e, err := sandbox.Setup(&s.cmd.ExtraFiles); err != nil {
+		return nil, fmsg.WrapErrorSuffix(err,
+			"cannot create shim setup pipe:")
+	} else {
+		s.encoder = e
+		s.cmd.Env = []string{
+			shimEnv + "=" + strconv.Itoa(fd),
+			"FORTIFY_APP_ID=" + aid,
+		}
+	}
+
+	// format fsu supplementary groups
+	if len(supp) > 0 {
+		fmsg.Verbosef("attaching supplementary group ids %s", supp)
+		s.cmd.Env = append(s.cmd.Env, "FORTIFY_GROUPS="+strings.Join(supp, " "))
+	}
+	s.cmd.Stdin, s.cmd.Stdout, s.cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
+	s.cmd.Dir = "/"
+
+	fmsg.Verbose("starting shim via fsu:", s.cmd)
+	// withhold messages to stderr
+	fmsg.Suspend()
+	if err := s.cmd.Start(); err != nil {
+		return nil, fmsg.WrapErrorSuffix(err,
+			"cannot start fsu:")
+	}
+	startTime := time.Now().UTC()
+
+	return &startTime, nil
+}
+
+func (s *shimProcess) Serve(ctx context.Context, params *shimParams) error {
+	// kill shim if something goes wrong and an error is returned
+	s.killFallback = make(chan error, 1)
+	killShim := func() {
+		if err := s.cmd.Process.Signal(os.Interrupt); err != nil {
+			s.killFallback <- err
+		}
+	}
+	defer func() { killShim() }()
+
+	encodeErr := make(chan error)
+	go func() { encodeErr <- s.encoder.Encode(params) }()
+
+	select {
+	// encode return indicates setup completion
+	case err := <-encodeErr:
+		if err != nil {
+			return fmsg.WrapErrorSuffix(err,
+				"cannot transmit shim config:")
+		}
+		killShim = func() {}
+		return nil
+
+	// setup canceled before payload was accepted
+	case <-ctx.Done():
+		err := ctx.Err()
+		if errors.Is(err, context.Canceled) {
+			return fmsg.WrapError(syscall.ECANCELED,
+				"shim setup canceled")
+		}
+		if errors.Is(err, context.DeadlineExceeded) {
+			return fmsg.WrapError(syscall.ETIMEDOUT,
+				"deadline exceeded waiting for shim")
+		}
+		// unreachable
+		return err
+	}
+}

internal/app/shim/main.go

@@ -1,153 +0,0 @@
-package shim
-
-import (
-	"context"
-	"errors"
-	"log"
-	"os"
-	"os/exec"
-	"os/signal"
-	"path"
-	"strconv"
-	"syscall"
-
-	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
-	"git.gensokyo.uk/security/fortify/internal"
-	init0 "git.gensokyo.uk/security/fortify/internal/app/init"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-// everything beyond this point runs as unconstrained target user
-// proceed with caution!
-
-func Main() {
-	// sharing stdout with fortify
-	// USE WITH CAUTION
-	fmsg.Prepare("shim")
-
-	// setting this prevents ptrace
-	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
-	}
-
-	// receive setup payload
-	var (
-		payload    Payload
-		closeSetup func() error
-	)
-	if f, err := proc.Receive(Env, &payload); err != nil {
-		if errors.Is(err, proc.ErrInvalid) {
-			log.Fatal("invalid config descriptor")
-		}
-		if errors.Is(err, proc.ErrNotSet) {
-			log.Fatal("FORTIFY_SHIM not set")
-		}
-
-		log.Fatalf("cannot decode shim setup payload: %v", err)
-	} else {
-		fmsg.Store(payload.Verbose)
-		closeSetup = f
-	}
-
-	if payload.Bwrap == nil {
-		log.Fatal("bwrap config not supplied")
-	}
-
-	// restore bwrap sync fd
-	var syncFd *os.File
-	if payload.Sync != nil {
-		syncFd = os.NewFile(*payload.Sync, "sync")
-	}
-
-	// close setup socket
-	if err := closeSetup(); err != nil {
-		log.Println("cannot close setup pipe:", err)
-		// not fatal
-	}
-
-	// ensure home directory as target user
-	if s, err := os.Stat(payload.Home); err != nil {
-		if os.IsNotExist(err) {
-			if err = os.Mkdir(payload.Home, 0700); err != nil {
-				log.Fatalf("cannot create home directory: %v", err)
-			}
-		} else {
-			log.Fatalf("cannot access home directory: %v", err)
-		}
-
-		// home directory is created, proceed
-	} else if !s.IsDir() {
-		log.Fatalf("data path %q is not a directory", payload.Home)
-	}
-
-	var ic init0.Payload
-
-	// resolve argv0
-	ic.Argv = payload.Argv
-	if len(ic.Argv) > 0 {
-		// looked up from $PATH by parent
-		ic.Argv0 = payload.Exec[1]
-	} else {
-		// no argv, look up shell instead
-		var ok bool
-		if payload.Bwrap.SetEnv == nil {
-			log.Fatal("no command was specified and environment is unset")
-		}
-		if ic.Argv0, ok = payload.Bwrap.SetEnv["SHELL"]; !ok {
-			log.Fatal("no command was specified and $SHELL was unset")
-		}
-
-		ic.Argv = []string{ic.Argv0}
-	}
-
-	conf := payload.Bwrap
-
-	var extraFiles []*os.File
-
-	// serve setup payload
-	if fd, encoder, err := proc.Setup(&extraFiles); err != nil {
-		log.Fatalf("cannot pipe: %v", err)
-	} else {
-		conf.SetEnv[init0.Env] = strconv.Itoa(fd)
-		go func() {
-			fmsg.Verbose("transmitting config to init")
-			if err = encoder.Encode(&ic); err != nil {
-				log.Fatalf("cannot transmit init config: %v", err)
-			}
-		}()
-	}
-
-	helper.BubblewrapName = payload.Exec[0] // resolved bwrap path by parent
-	if fmsg.Load() {
-		seccomp.CPrintln = log.Println
-	}
-	if b, err := helper.NewBwrap(
-		conf, path.Join(fst.Tmp, "sbin/init"), false,
-		nil, func(int, int) []string { return make([]string, 0) },
-		extraFiles,
-		syncFd,
-	); err != nil {
-		log.Fatalf("malformed sandbox config: %v", err)
-	} else {
-		b.Stdin(os.Stdin).Stdout(os.Stdout).Stderr(os.Stderr)
-		ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
-		defer stop() // unreachable
-
-		// run and pass through exit code
-		if err = b.Start(ctx, false); err != nil {
-			log.Fatalf("cannot start target process: %v", err)
-		} else if err = b.Wait(); err != nil {
-			var exitError *exec.ExitError
-			if !errors.As(err, &exitError) {
-				log.Printf("wait: %v", err)
-				internal.Exit(127)
-				panic("unreachable")
-			}
-			internal.Exit(exitError.ExitCode())
-			panic("unreachable")
-		}
-	}
-}

internal/app/shim/manager.go

@@ -1,133 +0,0 @@
-package shim
-
-import (
-	"context"
-	"encoding/gob"
-	"errors"
-	"os"
-	"os/exec"
-	"strconv"
-	"strings"
-	"time"
-
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/internal"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-// used by the parent process
-
-type Shim struct {
-	// user switcher process
-	cmd *exec.Cmd
-	// fallback exit notifier with error returned killing the process
-	killFallback chan error
-	// monitor to shim encoder
-	encoder *gob.Encoder
-	// bwrap --sync-fd value
-	sync *uintptr
-}
-
-func (s *Shim) String() string {
-	if s.cmd == nil {
-		return "(unused shim manager)"
-	}
-	return s.cmd.String()
-}
-
-func (s *Shim) Unwrap() *exec.Cmd {
-	return s.cmd
-}
-
-func (s *Shim) WaitFallback() chan error {
-	return s.killFallback
-}
-
-func (s *Shim) Start(
-	// string representation of application id
-	aid string,
-	// string representation of supplementary group ids
-	supp []string,
-	// bwrap --sync-fd
-	syncFd *os.File,
-) (*time.Time, error) {
-	// prepare user switcher invocation
-	fsuPath := internal.MustFsuPath()
-	s.cmd = exec.Command(fsuPath)
-
-	// pass shim setup pipe
-	if fd, e, err := proc.Setup(&s.cmd.ExtraFiles); err != nil {
-		return nil, fmsg.WrapErrorSuffix(err,
-			"cannot create shim setup pipe:")
-	} else {
-		s.encoder = e
-		s.cmd.Env = []string{
-			Env + "=" + strconv.Itoa(fd),
-			"FORTIFY_APP_ID=" + aid,
-		}
-	}
-
-	// format fsu supplementary groups
-	if len(supp) > 0 {
-		fmsg.Verbosef("attaching supplementary group ids %s", supp)
-		s.cmd.Env = append(s.cmd.Env, "FORTIFY_GROUPS="+strings.Join(supp, " "))
-	}
-	s.cmd.Stdin, s.cmd.Stdout, s.cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
-	s.cmd.Dir = "/"
-
-	// pass sync fd if set
-	if syncFd != nil {
-		fd := proc.ExtraFile(s.cmd, syncFd)
-		s.sync = &fd
-	}
-
-	fmsg.Verbose("starting shim via fsu:", s.cmd)
-	// withhold messages to stderr
-	fmsg.Suspend()
-	if err := s.cmd.Start(); err != nil {
-		return nil, fmsg.WrapErrorSuffix(err,
-			"cannot start fsu:")
-	}
-	startTime := time.Now().UTC()
-	return &startTime, nil
-}
-
-func (s *Shim) Serve(ctx context.Context, payload *Payload) error {
-	// kill shim if something goes wrong and an error is returned
-	s.killFallback = make(chan error, 1)
-	killShim := func() {
-		if err := s.cmd.Process.Signal(os.Interrupt); err != nil {
-			s.killFallback <- err
-		}
-	}
-	defer func() { killShim() }()
-
-	payload.Sync = s.sync
-	encodeErr := make(chan error)
-	go func() { encodeErr <- s.encoder.Encode(payload) }()
-
-	select {
-	// encode return indicates setup completion
-	case err := <-encodeErr:
-		if err != nil {
-			return fmsg.WrapErrorSuffix(err,
-				"cannot transmit shim config:")
-		}
-		killShim = func() {}
-		return nil
-
-	// setup canceled before payload was accepted
-	case <-ctx.Done():
-		err := ctx.Err()
-		if errors.Is(err, context.Canceled) {
-			return fmsg.WrapError(errors.New("shim setup canceled"),
-				"shim setup canceled")
-		}
-		if errors.Is(err, context.DeadlineExceeded) {
-			return fmsg.WrapError(errors.New("deadline exceeded waiting for shim"),
-				"deadline exceeded waiting for shim")
-		}
-		// unreachable
-		return err
-	}
-}

internal/app/shim/payload.go

@@ -1,23 +0,0 @@
-package shim
-
-import (
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-)
-
-const Env = "FORTIFY_SHIM"
-
-type Payload struct {
-	// child full argv
-	Argv []string
-	// bwrap, target full exec path
-	Exec [2]string
-	// bwrap config
-	Bwrap *bwrap.Config
-	// path to outer home directory
-	Home string
-	// sync fd
-	Sync *uintptr
-
-	// verbosity pass through
-	Verbose bool
-}

internal/fmsg/msg.go

@@ -0,0 +1,12 @@
+package fmsg
+
+type Output struct{}
+
+func (Output) IsVerbose() bool                         { return Load() }
+func (Output) Verbose(v ...any)                        { Verbose(v...) }
+func (Output) Verbosef(format string, v ...any)        { Verbosef(format, v...) }
+func (Output) WrapErr(err error, a ...any) error       { return WrapError(err, a...) }
+func (Output) PrintBaseErr(err error, fallback string) { PrintBaseError(err, fallback) }
+func (Output) Suspend()                                { Suspend() }
+func (Output) Resume() bool                            { return Resume() }
+func (Output) BeforeExit()                             { BeforeExit() }

internal/output.go

@@ -0,0 +1,17 @@
+package internal
+
+import (
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+	"git.gensokyo.uk/security/fortify/system"
+)
+
+func InstallFmsg(verbose bool) {
+	fmsg.Store(verbose)
+	sandbox.SetOutput(fmsg.Output{})
+	system.SetOutput(fmsg.Output{})
+	if verbose {
+		seccomp.SetOutput(fmsg.Verbose)
+	}
+}

internal/prctl.go

@@ -1,20 +0,0 @@
-package internal
-
-import "syscall"
-
-func PR_SET_DUMPABLE__SUID_DUMP_DISABLE() error {
-	// linux/sched/coredump.h
-	if _, _, errno := syscall.RawSyscall(syscall.SYS_PRCTL, syscall.PR_SET_DUMPABLE, 0, 0); errno != 0 {
-		return errno
-	}
-
-	return nil
-}
-
-func PR_SET_PDEATHSIG__SIGKILL() error {
-	if _, _, errno := syscall.RawSyscall(syscall.SYS_PRCTL, syscall.PR_SET_PDEATHSIG, uintptr(syscall.SIGKILL), 0); errno != 0 {
-		return errno
-	}
-
-	return nil
-}

internal/state/state_test.go

@@ -96,7 +96,7 @@ func testStore(t *testing.T, s state.Store) {
 		} else {
 			slices.Sort(aids)
 			want := []int{0, 1}
-			if slices.Compare(aids, want) != 0 {
+			if !slices.Equal(aids, want) {
 				t.Fatalf("List() = %#v, want %#v", aids, want)
 			}
 		}

internal/sys/interface.go

@@ -12,8 +12,10 @@ import (
 
 // State provides safe interaction with operating system state.
 type State interface {
-	// Geteuid provides [os.Geteuid].
-	Geteuid() int
+	// Getuid provides [os.Getuid].
+	Getuid() int
+	// Getgid provides [os.Getgid].
+	Getgid() int
 	// LookupEnv provides [os.LookupEnv].
 	LookupEnv(key string) (string, bool)
 	// TempDir provides [os.TempDir].
@@ -47,7 +49,7 @@ type State interface {
 
 // CopyPaths is a generic implementation of [System.Paths].
 func CopyPaths(os State, v *fst.Paths) {
-	v.SharePath = path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Geteuid()))
+	v.SharePath = path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Getuid()))
 
 	fmsg.Verbosef("process share directory at %q", v.SharePath)
 

internal/sys/std.go

@@ -15,6 +15,7 @@ import (
 	"git.gensokyo.uk/security/fortify/fst"
 	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/sandbox"
 )
 
 // Std implements System using the standard library.
@@ -30,11 +31,12 @@ type Std struct {
 	uidMu sync.RWMutex
 }
 
-func (s *Std) Geteuid() int                                 { return os.Geteuid() }
+func (s *Std) Getuid() int                                  { return os.Getuid() }
+func (s *Std) Getgid() int                                  { return os.Getgid() }
 func (s *Std) LookupEnv(key string) (string, bool)          { return os.LookupEnv(key) }
 func (s *Std) TempDir() string                              { return os.TempDir() }
 func (s *Std) LookPath(file string) (string, error)         { return exec.LookPath(file) }
-func (s *Std) MustExecutable() string                       { return internal.MustExecutable() }
+func (s *Std) MustExecutable() string                       { return sandbox.MustExecutable() }
 func (s *Std) LookupGroup(name string) (*user.Group, error) { return user.LookupGroup(name) }
 func (s *Std) ReadDir(name string) ([]os.DirEntry, error)   { return os.ReadDir(name) }
 func (s *Std) Stat(name string) (fs.FileInfo, error)        { return os.Stat(name) }

ldd/exec.go

@@ -3,56 +3,56 @@ package ldd
 import (
 	"bytes"
 	"context"
+	"io"
 	"os"
 	"os/exec"
 	"time"
 
-	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
+	"git.gensokyo.uk/security/fortify/sandbox"
 )
 
 const lddTimeout = 2 * time.Second
 
 var (
+	msgStatic      = []byte("Not a valid dynamic program")
 	msgStaticGlibc = []byte("not a dynamic executable")
 )
 
-func Exec(ctx context.Context, p string) ([]*Entry, error) {
-	var h helper.Helper
-
-	if toolPath, err := exec.LookPath("ldd"); err != nil {
-		return nil, err
-	} else if h, err = helper.NewBwrap(
-		(&bwrap.Config{
-			Hostname:      "fortify-ldd",
-			Chdir:         "/",
-			Syscall:       &bwrap.SyscallPolicy{DenyDevel: true, Multiarch: true},
-			NewSession:    true,
-			DieWithParent: true,
-		}).Bind("/", "/").DevTmpfs("/dev"), toolPath, false,
-		nil, func(_, _ int) []string { return []string{p} },
-		nil, nil,
-	); err != nil {
-		return nil, err
-	}
-
-	stdout, stderr := new(bytes.Buffer), new(bytes.Buffer)
-	h.Stdout(stdout).Stderr(stderr)
+func Exec(ctx context.Context, p string) ([]*Entry, error) { return ExecFilter(ctx, nil, nil, p) }
 
+func ExecFilter(ctx context.Context,
+	commandContext func(context.Context) *exec.Cmd,
+	f func([]byte) []byte,
+	p string) ([]*Entry, error) {
 	c, cancel := context.WithTimeout(ctx, lddTimeout)
 	defer cancel()
-	if err := h.Start(c, false); err != nil {
+	container := sandbox.New(c, "ldd", p)
+	container.CommandContext = commandContext
+	container.Hostname = "fortify-ldd"
+	stdout, stderr := new(bytes.Buffer), new(bytes.Buffer)
+	container.Stdout = stdout
+	container.Stderr = stderr
+	container.Bind("/", "/", 0).Proc("/proc").Dev("/dev")
+
+	if err := container.Start(); err != nil {
 		return nil, err
 	}
-	if err := h.Wait(); err != nil {
+	defer func() { _, _ = io.Copy(os.Stderr, stderr) }()
+	if err := container.Serve(); err != nil {
+		return nil, err
+	}
+	if err := container.Wait(); err != nil {
 		m := stderr.Bytes()
-		if bytes.Contains(m, msgStaticGlibc) {
+		if bytes.Contains(m, append([]byte(p+": "), msgStatic...)) ||
+			bytes.Contains(m, msgStaticGlibc) {
 			return nil, nil
 		}
-
-		_, _ = os.Stderr.Write(m)
 		return nil, err
 	}
 
-	return Parse(stdout)
+	v := stdout.Bytes()
+	if f != nil {
+		v = f(v)
+	}
+	return Parse(v)
 }

ldd/ldd.go

@@ -2,7 +2,6 @@
 package ldd
 
 import (
-	"fmt"
 	"math"
 	"path"
 	"strconv"
@@ -15,8 +14,8 @@ type Entry struct {
 	Location uint64 `json:"location"`
 }
 
-func Parse(stdout fmt.Stringer) ([]*Entry, error) {
-	payload := strings.Split(strings.TrimSpace(stdout.String()), "\n")
+func Parse(p []byte) ([]*Entry, error) {
+	payload := strings.Split(strings.TrimSpace(string(p)), "\n")
 	result := make([]*Entry, len(payload))
 
 	for i, ent := range payload {

ldd/ldd_test.go

@@ -3,7 +3,6 @@ package ldd_test
 import (
 	"errors"
 	"reflect"
-	"strings"
 	"testing"
 
 	"git.gensokyo.uk/security/fortify/ldd"
@@ -34,10 +33,7 @@ libzstd.so.1 => /usr/lib/libzstd.so.1 7ff71bfd2000
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			stdout := new(strings.Builder)
-			stdout.WriteString(tc.out)
-
-			if _, err := ldd.Parse(stdout); !errors.Is(err, tc.wantErr) {
+			if _, err := ldd.Parse([]byte(tc.out)); !errors.Is(err, tc.wantErr) {
 				t.Errorf("Parse() error = %v, wantErr %v", err, tc.wantErr)
 			}
 		})
@@ -111,10 +107,7 @@ libc.musl-x86_64.so.1 => /lib/ld-musl-x86_64.so.1 (0x7ff71c0a4000)`,
 	}
 	for _, tc := range testCases {
 		t.Run(tc.file, func(t *testing.T) {
-			stdout := new(strings.Builder)
-			stdout.WriteString(tc.out)
-
-			if got, err := ldd.Parse(stdout); err != nil {
+			if got, err := ldd.Parse([]byte(tc.out)); err != nil {
 				t.Errorf("Parse() error = %v", err)
 			} else if !reflect.DeepEqual(got, tc.want) {
 				t.Errorf("Parse() got = %#v, want %#v", got, tc.want)

ldd/path.go

@@ -0,0 +1,21 @@
+package ldd
+
+import (
+	"path"
+	"slices"
+)
+
+// Path returns a deterministic, deduplicated slice of absolute directory paths in entries.
+func Path(entries []*Entry) []string {
+	p := make([]string, 0, len(entries)*2)
+	for _, entry := range entries {
+		if path.IsAbs(entry.Path) {
+			p = append(p, path.Dir(entry.Path))
+		}
+		if path.IsAbs(entry.Name) {
+			p = append(p, path.Dir(entry.Name))
+		}
+	}
+	slices.Sort(p)
+	return slices.Compact(p)
+}

main.go

@@ -18,14 +18,12 @@ import (
 	"git.gensokyo.uk/security/fortify/command"
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
 	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/app"
-	init0 "git.gensokyo.uk/security/fortify/internal/app/init"
-	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/state"
 	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
 	"git.gensokyo.uk/security/fortify/system"
 )
 
@@ -41,10 +39,10 @@ func init() { fmsg.Prepare("fortify") }
 var std sys.State = new(sys.Std)
 
 func main() {
-	// early init argv0 check, skips root check and duplicate PR_SET_DUMPABLE
-	init0.TryArgv0()
+	// early init path, skips root check and duplicate PR_SET_DUMPABLE
+	sandbox.TryArgv0(fmsg.Output{}, fmsg.Prepare, internal.InstallFmsg)
 
-	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
+	if err := sandbox.SetDumpable(sandbox.SUID_DUMP_DISABLE); err != nil {
 		log.Printf("cannot set SUID_DUMP_DISABLE: %s", err)
 		// not fatal: this program runs as the privileged user
 	}
@@ -69,18 +67,13 @@ func buildCommand(out io.Writer) command.Command {
 		flagJSON    bool
 	)
 	c := command.New(out, log.Printf, "fortify", func([]string) error {
-		fmsg.Store(flagVerbose)
-		if flagVerbose {
-			seccomp.CPrintln = log.Println
-		}
+		internal.InstallFmsg(flagVerbose)
 		return nil
 	}).
 		Flag(&flagVerbose, "v", command.BoolFlag(false), "Print debug messages to the console").
 		Flag(&flagJSON, "json", command.BoolFlag(false), "Serialise output as JSON when applicable")
 
-	// internal commands
-	c.Command("shim", command.UsageInternal, func([]string) error { shim.Main(); return errSuccess })
-	c.Command("init", command.UsageInternal, func([]string) error { init0.Main(); return errSuccess })
+	c.Command("shim", command.UsageInternal, func([]string) error { app.ShimMain(); return errSuccess })
 
 	c.Command("app", "Launch app defined by the specified config file", func(args []string) error {
 		if len(args) < 1 {
@@ -89,10 +82,9 @@ func buildCommand(out io.Writer) command.Command {
 
 		// config extraArgs...
 		config := tryPath(args[0])
-		config.Command = append(config.Command, args[1:]...)
+		config.Args = append(config.Args, args[1:]...)
 
-		// invoke app
-		runApp(app.MustNew(std), config)
+		runApp(config)
 		panic("unreachable")
 	})
 
@@ -103,19 +95,20 @@ func buildCommand(out io.Writer) command.Command {
 			mpris             bool
 			dbusVerbose       bool
 
-			fid         string
-			aid         int
-			groups      command.RepeatableFlag
-			homeDir     string
-			userName    string
-			enablements [system.ELen]bool
+			fid      string
+			aid      int
+			groups   command.RepeatableFlag
+			homeDir  string
+			userName string
+
+			wayland, x11, dBus, pulse bool
 		)
 
 		c.NewCommand("run", "Configure and start a permissive default sandbox", func(args []string) error {
 			// initialise config from flags
 			config := &fst.Config{
-				ID:      fid,
-				Command: args,
+				ID:   fid,
+				Args: args,
 			}
 
 			if aid < 0 || aid > 9999 {
@@ -165,15 +158,21 @@ func buildCommand(out io.Writer) command.Command {
 			config.Confinement.Outer = homeDir
 			config.Confinement.Username = userName
 
-			// enablements from flags
-			for i := system.Enablement(0); i < system.Enablement(system.ELen); i++ {
-				if enablements[i] {
-					config.Confinement.Enablements.Set(i)
-				}
+			if wayland {
+				config.Confinement.Enablements |= system.EWayland
+			}
+			if x11 {
+				config.Confinement.Enablements |= system.EX11
+			}
+			if dBus {
+				config.Confinement.Enablements |= system.EDBus
+			}
+			if pulse {
+				config.Confinement.Enablements |= system.EPulse
 			}
 
 			// parse D-Bus config file from flags if applicable
-			if enablements[system.EDBus] {
+			if dBus {
 				if dbusConfigSession == "builtin" {
 					config.Confinement.SessionBus = dbus.NewConfig(fid, true, mpris)
 				} else {
@@ -201,7 +200,7 @@ func buildCommand(out io.Writer) command.Command {
 			}
 
 			// invoke app
-			runApp(app.MustNew(std), config)
+			runApp(config)
 			panic("unreachable")
 		}).
 			Flag(&dbusConfigSession, "dbus-config", command.StringFlag("builtin"),
@@ -222,13 +221,13 @@ func buildCommand(out io.Writer) command.Command {
 				"Application home directory").
 			Flag(&userName, "u", command.StringFlag("chronos"),
 				"Passwd name within sandbox").
-			Flag(&enablements[system.EWayland], "wayland", command.BoolFlag(false),
+			Flag(&wayland, "wayland", command.BoolFlag(false),
 				"Allow Wayland connections").
-			Flag(&enablements[system.EX11], "X", command.BoolFlag(false),
+			Flag(&x11, "X", command.BoolFlag(false),
 				"Share X11 socket and allow connection").
-			Flag(&enablements[system.EDBus], "dbus", command.BoolFlag(false),
+			Flag(&dBus, "dbus", command.BoolFlag(false),
 				"Proxy D-Bus connection").
-			Flag(&enablements[system.EPulse], "pulse", command.BoolFlag(false),
+			Flag(&pulse, "pulse", command.BoolFlag(false),
 				"Share PulseAudio socket and cookie")
 	}
 
@@ -281,10 +280,11 @@ func buildCommand(out io.Writer) command.Command {
 	return c
 }
 
-func runApp(a fst.App, config *fst.Config) {
+func runApp(config *fst.Config) {
 	ctx, stop := signal.NotifyContext(context.Background(),
 		syscall.SIGINT, syscall.SIGTERM)
 	defer stop() // unreachable
+	a := app.MustNew(ctx, std)
 
 	rs := new(fst.RunState)
 	if sa, err := a.Seal(config); err != nil {
@@ -292,7 +292,7 @@ func runApp(a fst.App, config *fst.Config) {
 		rs.ExitCode = 1
 	} else {
 		// this updates ExitCode
-		app.PrintRunStateErr(rs, sa.Run(ctx, rs))
+		app.PrintRunStateErr(rs, sa.Run(rs))
 	}
 	internal.Exit(rs.ExitCode)
 }

nixos.nix

@@ -1,3 +1,4 @@
+packages:
 {
   lib,
   pkgs,
@@ -26,7 +27,7 @@ let
 in
 
 {
-  imports = [ ./options.nix ];
+  imports = [ (import ./options.nix packages) ];
 
   config = mkIf cfg.enable {
     security.wrappers.fsu = {
@@ -83,14 +84,16 @@ in
                   command = if app.command == null then app.name else app.command;
                   script = if app.script == null then ("exec " + command + " $@") else app.script;
                   enablements = with app.capability; (if wayland then 1 else 0) + (if x11 then 2 else 0) + (if dbus then 4 else 0) + (if pulse then 8 else 0);
+                  isGraphical = if app.gpu != null then app.gpu else app.capability.wayland || app.capability.x11;
+
                   conf = {
                     inherit (app) id;
-                    command = [
-                      (pkgs.writeScript "${app.name}-start" ''
-                        #!${pkgs.zsh}${pkgs.zsh.shellPath}
-                        ${script}
-                      '')
-                    ];
+                    path = pkgs.writeScript "${app.name}-start" ''
+                      #!${pkgs.zsh}${pkgs.zsh.shellPath}
+                      ${script}
+                    '';
+                    args = [ "${app.name}-start" ];
+
                     confinement = {
                       app_id = aid;
                       inherit (app) groups;
@@ -98,18 +101,17 @@ in
                       home = getsubhome fid aid;
                       sandbox = {
                         inherit (app)
+                          devel
                           userns
                           net
                           dev
+                          tty
+                          multiarch
                           env
                           ;
-                        syscall = {
-                          inherit (app) compat multiarch bluetooth;
-                          deny_devel = !app.devel;
-                        };
                         map_real_uid = app.mapRealUid;
-                        no_new_session = app.tty;
                         direct_wayland = app.insecureWayland;
+
                         filesystem =
                           let
                             bind = src: { inherit src; };
@@ -126,7 +128,6 @@ in
                             (mustBind "/bin")
                             (mustBind "/usr/bin")
                             (mustBind "/nix/store")
-                            (mustBind "/run/current-system")
                             (bind "/sys/block")
                             (bind "/sys/bus")
                             (bind "/sys/class")
@@ -137,8 +138,7 @@ in
                             (mustBind "/nix/var")
                             (bind "/var/db/nix-channels")
                           ]
-                          ++ optionals (if app.gpu != null then app.gpu else app.capability.wayland || app.capability.x11) [
-                            (bind "/run/opengl-driver")
+                          ++ optionals isGraphical [
                             (devBind "/dev/dri")
                             (devBind "/dev/nvidiactl")
                             (devBind "/dev/nvidia-modeset")
@@ -148,8 +148,31 @@ in
                           ]
                           ++ app.extraPaths;
                         auto_etc = true;
-                        override = [ "/var/run/nscd" ];
+                        cover = [ "/var/run/nscd" ];
+
+                        symlink =
+                          [
+                            [
+                              "*/run/current-system"
+                              "/run/current-system"
+                            ]
+                          ]
+                          ++ optionals (isGraphical && config.hardware.graphics.enable) (
+                            [
+                              [
+                                config.systemd.tmpfiles.settings.graphics-driver."/run/opengl-driver"."L+".argument
+                                "/run/opengl-driver"
+                              ]
+                            ]
+                            ++ optionals (app.multiarch && config.hardware.graphics.enable32Bit) [
+                              [
+                                config.systemd.tmpfiles.settings.graphics-driver."/run/opengl-driver-32"."L+".argument
+                                /run/opengl-driver-32
+                              ]
+                            ]
+                          );
                       };
+
                       inherit enablements;
                       inherit (dbusConfig) session_bus system_bus;
                     };

options.md

@@ -21,7 +21,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.package
 
 
@@ -36,8 +35,7 @@ package
 
 
 *Default:*
-` <derivation fortify-static-x86_64-unknown-linux-musl-0.2.18> `
-
+` <derivation fortify-static-x86_64-unknown-linux-musl-0.3.1> `
 
 
 
@@ -57,7 +55,6 @@ list of (submodule)
 
 
 
-
 ## environment\.fortify\.apps\.\*\.packages
 
 
@@ -76,31 +73,6 @@ list of package
 
 
 
-
-## environment\.fortify\.apps\.\*\.bluetooth
-
-
-
-Whether to enable AF_BLUETOOTH socket operations\.
-
-
-
-*Type:*
-boolean
-
-
-
-*Default:*
-` false `
-
-
-
-*Example:*
-` true `
-
-
-
-
 ## environment\.fortify\.apps\.\*\.capability\.dbus
 
 
@@ -119,7 +91,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.capability\.pulse
 
 
@@ -138,7 +109,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.capability\.wayland
 
 
@@ -157,7 +127,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.capability\.x11
 
 
@@ -176,7 +145,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.command
 
 
@@ -197,31 +165,6 @@ null or string
 
 
 
-
-## environment\.fortify\.apps\.\*\.compat
-
-
-
-Whether to enable disable syscall filter extensions\.
-
-
-
-*Type:*
-boolean
-
-
-
-*Default:*
-` false `
-
-
-
-*Example:*
-` true `
-
-
-
-
 ## environment\.fortify\.apps\.\*\.dbus\.session
 
 
@@ -241,7 +184,6 @@ null or (function that evaluates to a(n) anything)
 
 
 
-
 ## environment\.fortify\.apps\.\*\.dbus\.system
 
 
@@ -261,7 +203,6 @@ null or anything
 
 
 
-
 ## environment\.fortify\.apps\.\*\.dev
 
 
@@ -285,12 +226,11 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.devel
 
 
 
-Whether to enable development kernel APIs\.
+Whether to enable debugging-related kernel interfaces\.
 
 
 
@@ -309,7 +249,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.env
 
 
@@ -328,7 +267,6 @@ null or (attribute set of string)
 
 
 
-
 ## environment\.fortify\.apps\.\*\.extraConfig
 
 
@@ -347,7 +285,6 @@ anything
 
 
 
-
 ## environment\.fortify\.apps\.\*\.extraPaths
 
 
@@ -366,7 +303,6 @@ list of anything
 
 
 
-
 ## environment\.fortify\.apps\.\*\.gpu
 
 
@@ -386,7 +322,6 @@ null or boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.groups
 
 
@@ -405,7 +340,6 @@ list of string
 
 
 
-
 ## environment\.fortify\.apps\.\*\.id
 
 
@@ -424,7 +358,6 @@ null or string
 
 
 
-
 ## environment\.fortify\.apps\.\*\.insecureWayland
 
 
@@ -448,7 +381,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.mapRealUid
 
 
@@ -472,12 +404,11 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.multiarch
 
 
 
-Whether to enable multiarch kernel support\.
+Whether to enable multiarch kernel-level support\.
 
 
 
@@ -496,7 +427,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.name
 
 
@@ -510,7 +440,6 @@ string
 
 
 
-
 ## environment\.fortify\.apps\.\*\.net
 
 
@@ -534,12 +463,11 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.nix
 
 
 
-Whether to enable nix daemon\.
+Whether to enable nix daemon access\.
 
 
 
@@ -558,7 +486,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.script
 
 
@@ -577,7 +504,6 @@ null or string
 
 
 
-
 ## environment\.fortify\.apps\.\*\.share
 
 
@@ -597,7 +523,6 @@ null or package
 
 
 
-
 ## environment\.fortify\.apps\.\*\.tty
 
 
@@ -621,12 +546,11 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.userns
 
 
 
-Whether to enable user namespace\.
+Whether to enable user namespace creation\.
 
 
 
@@ -645,7 +569,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.apps\.\*\.verbose
 
 
@@ -669,7 +592,6 @@ boolean
 
 
 
-
 ## environment\.fortify\.fsuPackage
 
 
@@ -684,8 +606,7 @@ package
 
 
 *Default:*
-` <derivation fortify-fsu-0.2.18> `
-
+` <derivation fortify-fsu-0.3.1> `
 
 
 
@@ -702,7 +623,6 @@ function that evaluates to a(n) function that evaluates to a(n) attribute set of
 
 
 
-
 ## environment\.fortify\.stateDir
 
 
@@ -716,7 +636,6 @@ string
 
 
 
-
 ## environment\.fortify\.users
 
 
@@ -729,4 +648,3 @@ Users allowed to spawn fortify apps and their corresponding fortify fid\.
 attribute set of integer between 0 and 99 (both inclusive)
 
 
-

options.nix

@@ -1,17 +1,8 @@
+packages:
 { lib, pkgs, ... }:
 
 let
   inherit (lib) types mkOption mkEnableOption;
-  fortify = pkgs.pkgsStatic.callPackage ./package.nix {
-    inherit (pkgs)
-      bubblewrap
-      xdg-dbus-proxy
-      glibc
-      zstd
-      gnutar
-      coreutils
-      ;
-  };
 in
 
 {
@@ -21,13 +12,13 @@ in
 
       package = mkOption {
         type = types.package;
-        default = fortify;
+        default = packages.${pkgs.system}.fortify;
         description = "The fortify package to use.";
       };
 
       fsuPackage = mkOption {
         type = types.package;
-        default = pkgs.callPackage ./cmd/fsu/package.nix { inherit fortify; };
+        default = packages.${pkgs.system}.fsu;
         description = "The fsu package to use.";
       };
 
@@ -157,21 +148,19 @@ in
                 '';
               };
 
-              nix = mkEnableOption "nix daemon";
-              userns = mkEnableOption "user namespace";
-              mapRealUid = mkEnableOption "mapping to priv-user uid";
-              dev = mkEnableOption "access to all devices";
+              devel = mkEnableOption "debugging-related kernel interfaces";
+              userns = mkEnableOption "user namespace creation";
               tty = mkEnableOption "access to the controlling terminal";
-              insecureWayland = mkEnableOption "direct access to the Wayland socket";
+              multiarch = mkEnableOption "multiarch kernel-level support";
 
               net = mkEnableOption "network access" // {
                 default = true;
               };
 
-              compat = mkEnableOption "disable syscall filter extensions";
-              devel = mkEnableOption "development kernel APIs";
-              multiarch = mkEnableOption "multiarch kernel support";
-              bluetooth = mkEnableOption "AF_BLUETOOTH socket operations";
+              nix = mkEnableOption "nix daemon access";
+              mapRealUid = mkEnableOption "mapping to priv-user uid";
+              dev = mkEnableOption "access to all devices";
+              insecureWayland = mkEnableOption "direct access to the Wayland socket";
 
               gpu = mkOption {
                 type = nullOr bool;

package.nix

@@ -4,7 +4,6 @@
   buildGoModule,
   makeBinaryWrapper,
   xdg-dbus-proxy,
-  bubblewrap,
   pkg-config,
   libffi,
   libseccomp,
@@ -19,18 +18,25 @@
   gnutar,
   coreutils,
 
+  # for passthru.buildInputs
+  go,
+  gcc,
+
+  # for check
+  util-linux,
+
   glibc, # for ldd
   withStatic ? stdenv.hostPlatform.isStatic,
 }:
 
 buildGoModule rec {
   pname = "fortify";
-  version = "0.2.18";
+  version = "0.3.1";
 
   src = builtins.path {
     name = "${pname}-src";
     path = lib.cleanSource ./.;
-    filter = path: type: !(type == "regular" && (lib.hasSuffix ".nix" path || lib.hasSuffix ".py" path)) && !(type == "directory" && lib.hasSuffix "/cmd/fsu" path);
+    filter = path: type: !(type == "regular" && (lib.hasSuffix ".nix" path || lib.hasSuffix ".py" path)) && !(type == "directory" && lib.hasSuffix "/test" path) && !(type == "directory" && lib.hasSuffix "/cmd/fsu" path);
   };
   vendorHash = null;
 
@@ -83,7 +89,6 @@ buildGoModule rec {
     let
       appPackages = [
         glibc
-        bubblewrap
         xdg-dbus-proxy
       ];
     in
@@ -108,4 +113,14 @@ buildGoModule rec {
           )
         }
     '';
+
+  passthru.targetPkgs =
+    [
+      go
+      gcc
+      xorg.xorgproto
+      util-linux
+    ]
+    ++ buildInputs
+    ++ nativeBuildInputs;
 }

parse.go

@@ -50,9 +50,12 @@ func tryPath(name string) (config *fst.Config) {
 
 func tryFd(name string) io.ReadCloser {
 	if v, err := strconv.Atoi(name); err != nil {
-		fmsg.Verbosef("name cannot be interpreted as int64: %v", err)
+		if !errors.Is(err, strconv.ErrSyntax) {
+			fmsg.Verbosef("name cannot be interpreted as int64: %v", err)
+		}
 		return nil
 	} else {
+		fmsg.Verbosef("trying config stream from %d", v)
 		fd := uintptr(v)
 		if _, _, errno := syscall.Syscall(syscall.SYS_FCNTL, fd, syscall.F_GETFD, 0); errno != 0 {
 			if errors.Is(errno, syscall.EBADF) {

print.go

@@ -89,10 +89,10 @@ func printShowInstance(
 				flags = append(flags, name)
 			}
 		}
-		writeFlag("userns", sandbox.UserNS)
+		writeFlag("userns", sandbox.Userns)
 		writeFlag("net", sandbox.Net)
 		writeFlag("dev", sandbox.Dev)
-		writeFlag("tty", sandbox.NoNewSession)
+		writeFlag("tty", sandbox.Tty)
 		writeFlag("mapuid", sandbox.MapRealUID)
 		writeFlag("directwl", sandbox.DirectWayland)
 		writeFlag("autoetc", sandbox.AutoEtc)
@@ -107,14 +107,14 @@ func printShowInstance(
 		}
 		t.Printf(" Etc:\t%s\n", etc)
 
-		if len(sandbox.Override) > 0 {
-			t.Printf(" Overrides:\t%s\n", strings.Join(sandbox.Override, " "))
+		if len(sandbox.Cover) > 0 {
+			t.Printf(" Cover:\t%s\n", strings.Join(sandbox.Cover, " "))
 		}
 
 		// Env           map[string]string   `json:"env"`
 		// Link          [][2]string         `json:"symlink"`
 	}
-	t.Printf(" Command:\t%s\n", strings.Join(config.Command, " "))
+	t.Printf(" Command:\t%s\n", strings.Join(config.Args, " "))
 	t.Printf("\n")
 
 	if !short {
@@ -256,7 +256,7 @@ func printPs(output io.Writer, now time.Time, s state.Store, short, flagJSON boo
 		)
 		if e.Config != nil {
 			es = e.Config.Confinement.Enablements.String()
-			cs = fmt.Sprintf("%q", e.Config.Command)
+			cs = fmt.Sprintf("%q", e.Config.Args)
 			as = strconv.Itoa(e.Config.Confinement.AppID)
 		}
 		t.Printf("\t%s\t%d\t%s\t%s\t%s\t%s\n",

print_test.go

@@ -37,13 +37,13 @@ func Test_printShowInstance(t *testing.T) {
 	}{
 		{"config", nil, fst.Template(), false, false, `App
  ID:             9 (org.chromium.Chromium)
- Enablements:    Wayland, D-Bus, PulseAudio
+ Enablements:    wayland, dbus, pulseaudio
  Groups:         ["video"]
  Directory:      /var/lib/persist/home/org.chromium.Chromium
  Hostname:       "localhost"
  Flags:          userns net dev tty mapuid autoetc
  Etc:            /etc
- Overrides:      /var/run/nscd
+ Cover:          /var/run/nscd
  Command:        chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
 
 Filesystem
@@ -74,14 +74,14 @@ System bus
 
 App
  ID:             0
- Enablements:    (No enablements)
+ Enablements:    (no enablements)
  Directory:      
  Command:        
 
 `},
 		{"config flag none", nil, &fst.Config{Confinement: fst.ConfinementConfig{Sandbox: new(fst.SandboxConfig)}}, false, false, `App
  ID:             0
- Enablements:    (No enablements)
+ Enablements:    (no enablements)
  Directory:      
  Flags:          none
  Etc:            /etc
@@ -90,7 +90,7 @@ App
 `},
 		{"config nil entries", nil, &fst.Config{Confinement: fst.ConfinementConfig{Sandbox: &fst.SandboxConfig{Filesystem: make([]*fst.FilesystemConfig, 1)}, ExtraPerms: make([]*fst.ExtraPermConfig, 1)}}, false, false, `App
  ID:             0
- Enablements:    (No enablements)
+ Enablements:    (no enablements)
  Directory:      
  Flags:          none
  Etc:            /etc
@@ -105,7 +105,7 @@ Extra ACL
 
 App
  ID:             0
- Enablements:    (No enablements)
+ Enablements:    (no enablements)
  Directory:      
  Command:        
 
@@ -121,13 +121,13 @@ Session bus
 
 App
  ID:             9 (org.chromium.Chromium)
- Enablements:    Wayland, D-Bus, PulseAudio
+ Enablements:    wayland, dbus, pulseaudio
  Groups:         ["video"]
  Directory:      /var/lib/persist/home/org.chromium.Chromium
  Hostname:       "localhost"
  Flags:          userns net dev tty mapuid autoetc
  Etc:            /etc
- Overrides:      /var/run/nscd
+ Cover:          /var/run/nscd
  Command:        chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
 
 Filesystem
@@ -162,7 +162,7 @@ State
 
 App
  ID:             0
- Enablements:    (No enablements)
+ Enablements:    (no enablements)
  Directory:      
  Command:        
 
@@ -192,7 +192,8 @@ App
   "pid": 3735928559,
   "config": {
     "id": "org.chromium.Chromium",
-    "command": [
+    "path": "/run/current-system/sw/bin/chromium",
+    "args": [
       "chromium",
       "--ignore-gpu-blocklist",
       "--disable-smooth-scrolling",
@@ -209,24 +210,19 @@ App
       "home": "/var/lib/persist/home/org.chromium.Chromium",
       "sandbox": {
         "hostname": "localhost",
+        "seccomp": 32,
+        "devel": true,
         "userns": true,
         "net": true,
-        "dev": true,
-        "syscall": {
-          "compat": false,
-          "deny_devel": true,
-          "multiarch": true,
-          "linux32": false,
-          "can": false,
-          "bluetooth": false
-        },
-        "no_new_session": true,
-        "map_real_uid": true,
+        "tty": true,
+        "multiarch": true,
         "env": {
           "GOOGLE_API_KEY": "AIzaSyBHDrl33hwRp4rMQY0ziRbj8K9LPA6vUCY",
           "GOOGLE_DEFAULT_CLIENT_ID": "77185425430.apps.googleusercontent.com",
           "GOOGLE_DEFAULT_CLIENT_SECRET": "OTJgUOQcT7lO7GsGZq2G4IlT"
         },
+        "map_real_uid": true,
+        "dev": true,
         "filesystem": [
           {
             "src": "/nix/store"
@@ -259,7 +255,7 @@ App
         ],
         "etc": "/etc",
         "auto_etc": true,
-        "override": [
+        "cover": [
           "/var/run/nscd"
         ]
       },
@@ -320,7 +316,8 @@ App
 `},
 		{"json config", nil, fst.Template(), false, true, `{
   "id": "org.chromium.Chromium",
-  "command": [
+  "path": "/run/current-system/sw/bin/chromium",
+  "args": [
     "chromium",
     "--ignore-gpu-blocklist",
     "--disable-smooth-scrolling",
@@ -337,24 +334,19 @@ App
     "home": "/var/lib/persist/home/org.chromium.Chromium",
     "sandbox": {
       "hostname": "localhost",
+      "seccomp": 32,
+      "devel": true,
       "userns": true,
       "net": true,
-      "dev": true,
-      "syscall": {
-        "compat": false,
-        "deny_devel": true,
-        "multiarch": true,
-        "linux32": false,
-        "can": false,
-        "bluetooth": false
-      },
-      "no_new_session": true,
-      "map_real_uid": true,
+      "tty": true,
+      "multiarch": true,
       "env": {
         "GOOGLE_API_KEY": "AIzaSyBHDrl33hwRp4rMQY0ziRbj8K9LPA6vUCY",
         "GOOGLE_DEFAULT_CLIENT_ID": "77185425430.apps.googleusercontent.com",
         "GOOGLE_DEFAULT_CLIENT_SECRET": "OTJgUOQcT7lO7GsGZq2G4IlT"
       },
+      "map_real_uid": true,
+      "dev": true,
       "filesystem": [
         {
           "src": "/nix/store"
@@ -387,7 +379,7 @@ App
       ],
       "etc": "/etc",
       "auto_etc": true,
-      "override": [
+      "cover": [
         "/var/run/nscd"
       ]
     },
@@ -477,8 +469,8 @@ func Test_printPs(t *testing.T) {
 
 `},
 
-		{"valid", state.Entries{testID: testState}, false, false, `    Instance    PID           App    Uptime     Enablements                   Command
-    8e2c76b0    3735928559    9      1h2m32s    Wayland, D-Bus, PulseAudio    ["chromium" "--ignore-gpu-blocklist" "--disable-smooth-scrolling" "--enable-features=UseOzonePlatform" "--ozone-platform=wayland"]
+		{"valid", state.Entries{testID: testState}, false, false, `    Instance    PID           App    Uptime     Enablements                  Command
+    8e2c76b0    3735928559    9      1h2m32s    wayland, dbus, pulseaudio    ["chromium" "--ignore-gpu-blocklist" "--disable-smooth-scrolling" "--enable-features=UseOzonePlatform" "--ozone-platform=wayland"]
 
 `},
 		{"valid short", state.Entries{testID: testState}, true, false, `8e2c76b0
@@ -506,7 +498,8 @@ func Test_printPs(t *testing.T) {
     "pid": 3735928559,
     "config": {
       "id": "org.chromium.Chromium",
-      "command": [
+      "path": "/run/current-system/sw/bin/chromium",
+      "args": [
         "chromium",
         "--ignore-gpu-blocklist",
         "--disable-smooth-scrolling",
@@ -523,24 +516,19 @@ func Test_printPs(t *testing.T) {
         "home": "/var/lib/persist/home/org.chromium.Chromium",
         "sandbox": {
           "hostname": "localhost",
+          "seccomp": 32,
+          "devel": true,
           "userns": true,
           "net": true,
-          "dev": true,
-          "syscall": {
-            "compat": false,
-            "deny_devel": true,
-            "multiarch": true,
-            "linux32": false,
-            "can": false,
-            "bluetooth": false
-          },
-          "no_new_session": true,
-          "map_real_uid": true,
+          "tty": true,
+          "multiarch": true,
           "env": {
             "GOOGLE_API_KEY": "AIzaSyBHDrl33hwRp4rMQY0ziRbj8K9LPA6vUCY",
             "GOOGLE_DEFAULT_CLIENT_ID": "77185425430.apps.googleusercontent.com",
             "GOOGLE_DEFAULT_CLIENT_SECRET": "OTJgUOQcT7lO7GsGZq2G4IlT"
           },
+          "map_real_uid": true,
+          "dev": true,
           "filesystem": [
             {
               "src": "/nix/store"
@@ -573,7 +561,7 @@ func Test_printPs(t *testing.T) {
           ],
           "etc": "/etc",
           "auto_etc": true,
-          "override": [
+          "cover": [
             "/var/run/nscd"
           ]
         },

sandbox/container.go

@@ -0,0 +1,252 @@
+// Package sandbox implements unprivileged Linux container with hardening options useful for creating application sandboxes.
+package sandbox
+
+import (
+	"context"
+	"encoding/gob"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path"
+	"strconv"
+	"syscall"
+	"time"
+
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+)
+
+type HardeningFlags uintptr
+
+const (
+	FSyscallCompat HardeningFlags = 1 << iota
+	FAllowDevel
+	FAllowUserns
+	FAllowTTY
+	FAllowNet
+)
+
+func (flags HardeningFlags) seccomp(opts seccomp.SyscallOpts) seccomp.SyscallOpts {
+	if flags&FSyscallCompat == 0 {
+		opts |= seccomp.FlagExt
+	}
+	if flags&FAllowDevel == 0 {
+		opts |= seccomp.FlagDenyDevel
+	}
+	if flags&FAllowUserns == 0 {
+		opts |= seccomp.FlagDenyNS
+	}
+	if flags&FAllowTTY == 0 {
+		opts |= seccomp.FlagDenyTTY
+	}
+	return opts
+}
+
+type (
+	// Container represents a container environment being prepared or run.
+	// None of [Container] methods are safe for concurrent use.
+	Container struct {
+		// Name of initial process in the container.
+		name string
+		// Cgroup fd, nil to disable.
+		Cgroup *int
+		// ExtraFiles passed through to initial process in the container,
+		// with behaviour identical to its [exec.Cmd] counterpart.
+		ExtraFiles []*os.File
+
+		// Custom [exec.Cmd] initialisation function.
+		CommandContext func(ctx context.Context) (cmd *exec.Cmd)
+
+		// param encoder for shim and init
+		setup *gob.Encoder
+		// cancels cmd
+		cancel context.CancelFunc
+
+		Stdin  io.Reader
+		Stdout io.Writer
+		Stderr io.Writer
+
+		Cancel    func(cmd *exec.Cmd) error
+		WaitDelay time.Duration
+
+		cmd *exec.Cmd
+		ctx context.Context
+		Params
+	}
+
+	// Params holds container configuration and is safe to serialise.
+	Params struct {
+		// Working directory in the container.
+		Dir string
+		// Initial process environment.
+		Env []string
+		// Absolute path of initial process in the container. Overrides name.
+		Path string
+		// Initial process argv.
+		Args []string
+
+		// Mapped Uid in user namespace.
+		Uid int
+		// Mapped Gid in user namespace.
+		Gid int
+		// Hostname value in UTS namespace.
+		Hostname string
+		// Sequential container setup ops.
+		*Ops
+		// Extra seccomp options.
+		Seccomp seccomp.SyscallOpts
+		// Permission bits of newly created parent directories.
+		// The zero value is interpreted as 0755.
+		ParentPerm os.FileMode
+
+		Flags HardeningFlags
+	}
+
+	Ops []Op
+	Op  interface {
+		early(params *Params) error
+		apply(params *Params) error
+		prefix() string
+
+		Is(op Op) bool
+		fmt.Stringer
+	}
+)
+
+func (p *Container) Start() error {
+	if p.cmd != nil {
+		return errors.New("sandbox: already started")
+	}
+	if p.Ops == nil || len(*p.Ops) == 0 {
+		return errors.New("sandbox: starting an empty container")
+	}
+
+	ctx, cancel := context.WithCancel(p.ctx)
+	p.cancel = cancel
+
+	var cloneFlags uintptr = syscall.CLONE_NEWIPC |
+		syscall.CLONE_NEWUTS |
+		syscall.CLONE_NEWCGROUP
+	if p.Flags&FAllowNet == 0 {
+		cloneFlags |= syscall.CLONE_NEWNET
+	}
+
+	// map to overflow id to work around ownership checks
+	if p.Uid < 1 {
+		p.Uid = OverflowUid()
+	}
+	if p.Gid < 1 {
+		p.Gid = OverflowGid()
+	}
+
+	if p.CommandContext != nil {
+		p.cmd = p.CommandContext(ctx)
+	} else {
+		p.cmd = exec.CommandContext(ctx, MustExecutable())
+		p.cmd.Args = []string{"init"}
+	}
+
+	p.cmd.Stdin, p.cmd.Stdout, p.cmd.Stderr = p.Stdin, p.Stdout, p.Stderr
+	p.cmd.WaitDelay = p.WaitDelay
+	if p.Cancel != nil {
+		p.cmd.Cancel = func() error { return p.Cancel(p.cmd) }
+	} else {
+		p.cmd.Cancel = func() error { return p.cmd.Process.Signal(syscall.SIGTERM) }
+	}
+	p.cmd.Dir = "/"
+	p.cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setsid:    p.Flags&FAllowTTY == 0,
+		Pdeathsig: syscall.SIGKILL,
+
+		Cloneflags: cloneFlags |
+			syscall.CLONE_NEWUSER |
+			syscall.CLONE_NEWPID |
+			syscall.CLONE_NEWNS,
+
+		// remain privileged for setup
+		AmbientCaps: []uintptr{CAP_SYS_ADMIN, CAP_SETPCAP},
+
+		UseCgroupFD: p.Cgroup != nil,
+	}
+	if p.cmd.SysProcAttr.UseCgroupFD {
+		p.cmd.SysProcAttr.CgroupFD = *p.Cgroup
+	}
+
+	// place setup pipe before user supplied extra files, this is later restored by init
+	if fd, e, err := Setup(&p.cmd.ExtraFiles); err != nil {
+		return wrapErrSuffix(err,
+			"cannot create shim setup pipe:")
+	} else {
+		p.setup = e
+		p.cmd.Env = []string{setupEnv + "=" + strconv.Itoa(fd)}
+	}
+	p.cmd.ExtraFiles = append(p.cmd.ExtraFiles, p.ExtraFiles...)
+
+	msg.Verbose("starting container init")
+	if err := p.cmd.Start(); err != nil {
+		return msg.WrapErr(err, err.Error())
+	}
+	return nil
+}
+
+func (p *Container) Serve() error {
+	if p.setup == nil {
+		panic("invalid serve")
+	}
+
+	setup := p.setup
+	p.setup = nil
+
+	if p.Path != "" && !path.IsAbs(p.Path) {
+		p.cancel()
+		return msg.WrapErr(syscall.EINVAL,
+			fmt.Sprintf("invalid executable path %q", p.Path))
+	}
+
+	if p.Path == "" {
+		if p.name == "" {
+			p.Path = os.Getenv("SHELL")
+			if !path.IsAbs(p.Path) {
+				p.cancel()
+				return msg.WrapErr(syscall.EBADE,
+					"no command specified and $SHELL is invalid")
+			}
+			p.name = path.Base(p.Path)
+		} else if path.IsAbs(p.name) {
+			p.Path = p.name
+		} else if v, err := exec.LookPath(p.name); err != nil {
+			p.cancel()
+			return msg.WrapErr(err, err.Error())
+		} else {
+			p.Path = v
+		}
+	}
+
+	err := setup.Encode(
+		&initParams{
+			p.Params,
+			syscall.Getuid(),
+			syscall.Getgid(),
+			len(p.ExtraFiles),
+			msg.IsVerbose(),
+		},
+	)
+	if err != nil {
+		p.cancel()
+	}
+	return err
+}
+
+func (p *Container) Wait() error { defer p.cancel(); return p.cmd.Wait() }
+
+func (p *Container) String() string {
+	return fmt.Sprintf("argv: %q, flags: %#x, seccomp: %#x",
+		p.Args, p.Flags, int(p.Flags.seccomp(p.Seccomp)))
+}
+
+func New(ctx context.Context, name string, args ...string) *Container {
+	return &Container{name: name, ctx: ctx,
+		Params: Params{Args: append([]string{name}, args...), Dir: "/", Ops: new(Ops)},
+	}
+}

sandbox/container_test.go

@@ -0,0 +1,255 @@
+package sandbox_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/gob"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"testing"
+	"time"
+
+	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/ldd"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+const (
+	ignore  = "\x00"
+	ignoreV = -1
+)
+
+func TestContainer(t *testing.T) {
+	{
+		oldVerbose := fmsg.Load()
+		oldOutput := sandbox.GetOutput()
+		internal.InstallFmsg(true)
+		t.Cleanup(func() { fmsg.Store(oldVerbose) })
+		t.Cleanup(func() { sandbox.SetOutput(oldOutput) })
+	}
+
+	testCases := []struct {
+		name  string
+		flags sandbox.HardeningFlags
+		ops   *sandbox.Ops
+		mnt   []*vfs.MountInfoEntry
+		host  string
+	}{
+		{"minimal", 0, new(sandbox.Ops), nil, "test-minimal"},
+		{"allow", sandbox.FAllowUserns | sandbox.FAllowNet | sandbox.FAllowTTY,
+			new(sandbox.Ops), nil, "test-minimal"},
+		{"tmpfs", 0,
+			new(sandbox.Ops).
+				Tmpfs(fst.Tmp, 0, 0755),
+			[]*vfs.MountInfoEntry{
+				e("/", fst.Tmp, "rw,nosuid,nodev,relatime", "tmpfs", "tmpfs", ignore),
+			}, "test-tmpfs"},
+		{"dev", sandbox.FAllowTTY, // go test output is not a tty
+			new(sandbox.Ops).
+				Dev("/dev").
+				Mqueue("/dev/mqueue"),
+			[]*vfs.MountInfoEntry{
+				e("/", "/dev", "rw,nosuid,nodev,relatime", "tmpfs", "devtmpfs", ignore),
+				e("/null", "/dev/null", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/zero", "/dev/zero", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/full", "/dev/full", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/random", "/dev/random", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/urandom", "/dev/urandom", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/tty", "/dev/tty", "rw,nosuid", "devtmpfs", "devtmpfs", ignore),
+				e("/", "/dev/pts", "rw,nosuid,noexec,relatime", "devpts", "devpts", "rw,mode=620,ptmxmode=666"),
+				e("/", "/dev/mqueue", "rw,nosuid,nodev,noexec,relatime", "mqueue", "mqueue", "rw"),
+			}, ""},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+
+			container := sandbox.New(ctx, "/usr/bin/sandbox.test", "-test.v",
+				"-test.run=TestHelperCheckContainer", "--", "check", tc.host)
+			container.Uid = 1000
+			container.Gid = 100
+			container.Hostname = tc.host
+			container.CommandContext = commandContext
+			container.Flags |= tc.flags
+			container.Stdout, container.Stderr = os.Stdout, os.Stderr
+			container.Ops = tc.ops
+			if container.Args[5] == "" {
+				if name, err := os.Hostname(); err != nil {
+					t.Fatalf("cannot get hostname: %v", err)
+				} else {
+					container.Args[5] = name
+				}
+			}
+
+			container.
+				Tmpfs("/tmp", 0, 0755).
+				Bind(os.Args[0], os.Args[0], 0).
+				Mkdir("/usr/bin", 0755).
+				Link(os.Args[0], "/usr/bin/sandbox.test").
+				Place("/etc/hostname", []byte(container.Args[5]))
+			// in case test has cgo enabled
+			var libPaths []string
+			if entries, err := ldd.ExecFilter(ctx,
+				commandContext,
+				func(v []byte) []byte {
+					return bytes.SplitN(v, []byte("TestHelperInit\n"), 2)[1]
+				}, os.Args[0]); err != nil {
+				log.Fatalf("ldd: %v", err)
+			} else {
+				libPaths = ldd.Path(entries)
+			}
+			for _, name := range libPaths {
+				container.Bind(name, name, 0)
+			}
+			// needs /proc to check mountinfo
+			container.Proc("/proc")
+
+			mnt := make([]*vfs.MountInfoEntry, 0, 3+len(libPaths))
+			mnt = append(mnt, e("/sysroot", "/", "rw,nosuid,nodev,relatime", "tmpfs", "rootfs", ignore))
+			mnt = append(mnt, tc.mnt...)
+			mnt = append(mnt,
+				e("/", "/tmp", "rw,nosuid,nodev,relatime", "tmpfs", "tmpfs", ignore),
+				e(ignore, os.Args[0], "ro,nosuid,nodev,relatime", ignore, ignore, ignore),
+				e(ignore, "/etc/hostname", "ro,nosuid,nodev,relatime", "tmpfs", "rootfs", ignore),
+			)
+			for _, name := range libPaths {
+				mnt = append(mnt, e(ignore, name, "ro,nosuid,nodev,relatime", ignore, ignore, ignore))
+			}
+			mnt = append(mnt, e("/", "/proc", "rw,nosuid,nodev,noexec,relatime", "proc", "proc", "rw"))
+			want := new(bytes.Buffer)
+			if err := gob.NewEncoder(want).Encode(mnt); err != nil {
+				t.Fatalf("cannot serialise expected mount points: %v", err)
+			}
+			container.Stdin = want
+
+			if err := container.Start(); err != nil {
+				fmsg.PrintBaseError(err, "start:")
+				t.Fatalf("cannot start container: %v", err)
+			} else if err = container.Serve(); err != nil {
+				fmsg.PrintBaseError(err, "serve:")
+				t.Errorf("cannot serve setup params: %v", err)
+			}
+			if err := container.Wait(); err != nil {
+				fmsg.PrintBaseError(err, "wait:")
+				t.Fatalf("wait: %v", err)
+			}
+		})
+	}
+}
+
+func e(root, target, vfsOptstr, fsType, source, fsOptstr string) *vfs.MountInfoEntry {
+	return &vfs.MountInfoEntry{
+		ID:        ignoreV,
+		Parent:    ignoreV,
+		Devno:     vfs.DevT{ignoreV, ignoreV},
+		Root:      root,
+		Target:    target,
+		VfsOptstr: vfsOptstr,
+		OptFields: []string{ignore},
+		FsType:    fsType,
+		Source:    source,
+		FsOptstr:  fsOptstr,
+	}
+}
+
+func TestContainerString(t *testing.T) {
+	container := sandbox.New(context.TODO(), "ldd", "/usr/bin/env")
+	container.Flags |= sandbox.FAllowDevel
+	container.Seccomp |= seccomp.FlagMultiarch
+	want := `argv: ["ldd" "/usr/bin/env"], flags: 0x2, seccomp: 0x2e`
+	if got := container.String(); got != want {
+		t.Errorf("String: %s, want %s", got, want)
+	}
+}
+
+func TestHelperInit(t *testing.T) {
+	if len(os.Args) != 5 || os.Args[4] != "init" {
+		return
+	}
+	sandbox.SetOutput(fmsg.Output{})
+	sandbox.Init(fmsg.Prepare, internal.InstallFmsg)
+}
+
+func TestHelperCheckContainer(t *testing.T) {
+	if len(os.Args) != 6 || os.Args[4] != "check" {
+		return
+	}
+
+	t.Run("user", func(t *testing.T) {
+		if uid := syscall.Getuid(); uid != 1000 {
+			t.Errorf("Getuid: %d, want 1000", uid)
+		}
+		if gid := syscall.Getgid(); gid != 100 {
+			t.Errorf("Getgid: %d, want 100", gid)
+		}
+	})
+	t.Run("hostname", func(t *testing.T) {
+		if name, err := os.Hostname(); err != nil {
+			t.Fatalf("cannot get hostname: %v", err)
+		} else if name != os.Args[5] {
+			t.Errorf("Hostname: %q, want %q", name, os.Args[5])
+		}
+
+		if p, err := os.ReadFile("/etc/hostname"); err != nil {
+			t.Fatalf("%v", err)
+		} else if string(p) != os.Args[5] {
+			t.Errorf("/etc/hostname: %q, want %q", string(p), os.Args[5])
+		}
+	})
+	t.Run("mount", func(t *testing.T) {
+		var mnt []*vfs.MountInfoEntry
+		if err := gob.NewDecoder(os.Stdin).Decode(&mnt); err != nil {
+			t.Fatalf("cannot receive expected mount points: %v", err)
+		}
+
+		var d *vfs.MountInfoDecoder
+		if f, err := os.Open("/proc/self/mountinfo"); err != nil {
+			t.Fatalf("cannot open mountinfo: %v", err)
+		} else {
+			d = vfs.NewMountInfoDecoder(f)
+		}
+
+		i := 0
+		for cur := range d.Entries() {
+			if i == len(mnt) {
+				t.Errorf("got more than %d entries", len(mnt))
+				break
+			}
+
+			// ugly hack but should be reliable and is less likely to false negative than comparing by parsed flags
+			cur.VfsOptstr = strings.TrimSuffix(cur.VfsOptstr, ",relatime")
+			cur.VfsOptstr = strings.TrimSuffix(cur.VfsOptstr, ",noatime")
+			mnt[i].VfsOptstr = strings.TrimSuffix(mnt[i].VfsOptstr, ",relatime")
+			mnt[i].VfsOptstr = strings.TrimSuffix(mnt[i].VfsOptstr, ",noatime")
+
+			if !cur.EqualWithIgnore(mnt[i], "\x00") {
+				t.Errorf("[FAIL] %s", cur)
+			} else {
+				t.Logf("[ OK ] %s", cur)
+			}
+
+			i++
+		}
+		if err := d.Err(); err != nil {
+			t.Errorf("cannot parse mountinfo: %v", err)
+		}
+
+		if i != len(mnt) {
+			t.Errorf("got %d entries, want %d", i, len(mnt))
+		}
+	})
+}
+
+func commandContext(ctx context.Context) *exec.Cmd {
+	return exec.CommandContext(ctx, os.Args[0], "-test.v",
+		"-test.run=TestHelperInit", "--", "init")
+}

sandbox/executable.go

@@ -1,11 +1,9 @@
-package internal
+package sandbox
 
 import (
 	"log"
 	"os"
 	"sync"
-
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
 var (
@@ -15,7 +13,7 @@ var (
 
 func copyExecutable() {
 	if name, err := os.Executable(); err != nil {
-		fmsg.BeforeExit()
+		msg.BeforeExit()
 		log.Fatalf("cannot read executable path: %v", err)
 	} else {
 		executable = name

sandbox/executable_test.go

@@ -0,0 +1,17 @@
+package sandbox_test
+
+import (
+	"os"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/sandbox"
+)
+
+func TestExecutable(t *testing.T) {
+	for i := 0; i < 16; i++ {
+		if got := sandbox.MustExecutable(); got != os.Args[0] {
+			t.Errorf("MustExecutable: %q, want %q",
+				got, os.Args[0])
+		}
+	}
+}

sandbox/init.go

@@ -0,0 +1,378 @@
+package sandbox
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path"
+	"runtime"
+	"strconv"
+	"syscall"
+	"time"
+
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+)
+
+const (
+	// time to wait for linger processes after death of initial process
+	residualProcessTimeout = 5 * time.Second
+
+	// intermediate tmpfs mount point
+	basePath = "/tmp"
+
+	// setup params file descriptor
+	setupEnv = "FORTIFY_SETUP"
+)
+
+type initParams struct {
+	Params
+
+	HostUid, HostGid int
+	// extra files count
+	Count int
+	// verbosity pass through
+	Verbose bool
+}
+
+func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
+	runtime.LockOSThread()
+	prepare("init")
+
+	if os.Getpid() != 1 {
+		log.Fatal("this process must run as pid 1")
+	}
+
+	/*
+		receive setup payload
+	*/
+
+	var (
+		params      initParams
+		closeSetup  func() error
+		setupFile   *os.File
+		offsetSetup int
+	)
+	if f, err := Receive(setupEnv, &params, &setupFile); err != nil {
+		if errors.Is(err, ErrInvalid) {
+			log.Fatal("invalid setup descriptor")
+		}
+		if errors.Is(err, ErrNotSet) {
+			log.Fatal("FORTIFY_SETUP not set")
+		}
+
+		log.Fatalf("cannot decode init setup payload: %v", err)
+	} else {
+		if params.Ops == nil {
+			log.Fatal("invalid setup parameters")
+		}
+		if params.ParentPerm == 0 {
+			params.ParentPerm = 0755
+		}
+
+		setVerbose(params.Verbose)
+		msg.Verbose("received setup parameters")
+		closeSetup = f
+		offsetSetup = int(setupFile.Fd() + 1)
+	}
+
+	// write uid/gid map here so parent does not need to set dumpable
+	if err := SetDumpable(SUID_DUMP_USER); err != nil {
+		log.Fatalf("cannot set SUID_DUMP_USER: %s", err)
+	}
+	if err := os.WriteFile("/proc/self/uid_map",
+		append([]byte{}, strconv.Itoa(params.Uid)+" "+strconv.Itoa(params.HostUid)+" 1\n"...),
+		0); err != nil {
+		log.Fatalf("%v", err)
+	}
+	if err := os.WriteFile("/proc/self/setgroups",
+		[]byte("deny\n"),
+		0); err != nil && !os.IsNotExist(err) {
+		log.Fatalf("%v", err)
+	}
+	if err := os.WriteFile("/proc/self/gid_map",
+		append([]byte{}, strconv.Itoa(params.Gid)+" "+strconv.Itoa(params.HostGid)+" 1\n"...),
+		0); err != nil {
+		log.Fatalf("%v", err)
+	}
+	if err := SetDumpable(SUID_DUMP_DISABLE); err != nil {
+		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
+	}
+
+	oldmask := syscall.Umask(0)
+	if params.Hostname != "" {
+		if err := syscall.Sethostname([]byte(params.Hostname)); err != nil {
+			log.Fatalf("cannot set hostname: %v", err)
+		}
+	}
+
+	// cache sysctl before pivot_root
+	LastCap()
+
+	/*
+		set up mount points from intermediate root
+	*/
+
+	if err := syscall.Mount("", "/", "",
+		syscall.MS_SILENT|syscall.MS_SLAVE|syscall.MS_REC,
+		""); err != nil {
+		log.Fatalf("cannot make / rslave: %v", err)
+	}
+
+	for i, op := range *params.Ops {
+		if op == nil {
+			log.Fatalf("invalid op %d", i)
+		}
+
+		if err := op.early(&params.Params); err != nil {
+			msg.PrintBaseErr(err,
+				fmt.Sprintf("cannot prepare op %d:", i))
+			msg.BeforeExit()
+			os.Exit(1)
+		}
+	}
+
+	if err := syscall.Mount("rootfs", basePath, "tmpfs",
+		syscall.MS_NODEV|syscall.MS_NOSUID,
+		""); err != nil {
+		log.Fatalf("cannot mount intermediate root: %v", err)
+	}
+	if err := os.Chdir(basePath); err != nil {
+		log.Fatalf("cannot enter base path: %v", err)
+	}
+
+	if err := os.Mkdir(sysrootDir, 0755); err != nil {
+		log.Fatalf("%v", err)
+	}
+	if err := syscall.Mount(sysrootDir, sysrootDir, "",
+		syscall.MS_SILENT|syscall.MS_MGC_VAL|syscall.MS_BIND|syscall.MS_REC,
+		""); err != nil {
+		log.Fatalf("cannot bind sysroot: %v", err)
+	}
+
+	if err := os.Mkdir(hostDir, 0755); err != nil {
+		log.Fatalf("%v", err)
+	}
+	if err := syscall.PivotRoot(basePath, hostDir); err != nil {
+		log.Fatalf("cannot pivot into intermediate root: %v", err)
+	}
+	if err := os.Chdir("/"); err != nil {
+		log.Fatalf("%v", err)
+	}
+
+	for i, op := range *params.Ops {
+		// ops already checked during early setup
+		msg.Verbosef("%s %s", op.prefix(), op)
+		if err := op.apply(&params.Params); err != nil {
+			msg.PrintBaseErr(err,
+				fmt.Sprintf("cannot apply op %d:", i))
+			msg.BeforeExit()
+			os.Exit(1)
+		}
+	}
+
+	/*
+		pivot to sysroot
+	*/
+
+	if err := syscall.Mount(hostDir, hostDir, "",
+		syscall.MS_SILENT|syscall.MS_REC|syscall.MS_PRIVATE,
+		""); err != nil {
+		log.Fatalf("cannot make host root rprivate: %v", err)
+	}
+	if err := syscall.Unmount(hostDir, syscall.MNT_DETACH); err != nil {
+		log.Fatalf("cannot unmount host root: %v", err)
+	}
+
+	{
+		var fd int
+		if err := IgnoringEINTR(func() (err error) {
+			fd, err = syscall.Open("/", syscall.O_DIRECTORY|syscall.O_RDONLY, 0)
+			return
+		}); err != nil {
+			log.Fatalf("cannot open intermediate root: %v", err)
+		}
+		if err := os.Chdir(sysrootPath); err != nil {
+			log.Fatalf("%v", err)
+		}
+
+		if err := syscall.PivotRoot(".", "."); err != nil {
+			log.Fatalf("cannot pivot into sysroot: %v", err)
+		}
+		if err := syscall.Fchdir(fd); err != nil {
+			log.Fatalf("cannot re-enter intermediate root: %v", err)
+		}
+		if err := syscall.Unmount(".", syscall.MNT_DETACH); err != nil {
+			log.Fatalf("cannot unmount intemediate root: %v", err)
+		}
+		if err := os.Chdir("/"); err != nil {
+			log.Fatalf("%v", err)
+		}
+
+		if err := syscall.Close(fd); err != nil {
+			log.Fatalf("cannot close intermediate root: %v", err)
+		}
+	}
+
+	/*
+		caps/securebits and seccomp filter
+	*/
+
+	if _, _, errno := syscall.Syscall(PR_SET_NO_NEW_PRIVS, 1, 0, 0); errno != 0 {
+		log.Fatalf("prctl(PR_SET_NO_NEW_PRIVS): %v", errno)
+	}
+	if _, _, errno := syscall.Syscall(syscall.SYS_PRCTL, PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0); errno != 0 {
+		log.Fatalf("cannot clear the ambient capability set: %v", errno)
+	}
+	for i := uintptr(0); i <= LastCap(); i++ {
+		if _, _, errno := syscall.Syscall(syscall.SYS_PRCTL, syscall.PR_CAPBSET_DROP, i, 0); errno != 0 {
+			log.Fatalf("cannot drop capability from bonding set: %v", errno)
+		}
+	}
+	if err := capset(
+		&capHeader{_LINUX_CAPABILITY_VERSION_3, 0},
+		&[2]capData{{0, 0, 0}, {0, 0, 0}},
+	); err != nil {
+		log.Fatalf("cannot capset: %v", err)
+	}
+
+	if err := seccomp.Load(params.Flags.seccomp(params.Seccomp)); err != nil {
+		log.Fatalf("cannot load syscall filter: %v", err)
+	}
+
+	/*
+		pass through extra files
+	*/
+
+	extraFiles := make([]*os.File, params.Count)
+	for i := range extraFiles {
+		extraFiles[i] = os.NewFile(uintptr(offsetSetup+i), "extra file "+strconv.Itoa(i))
+	}
+	syscall.Umask(oldmask)
+
+	/*
+		prepare initial process
+	*/
+
+	cmd := exec.Command(params.Path)
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
+	cmd.Args = params.Args
+	cmd.Env = params.Env
+	cmd.ExtraFiles = extraFiles
+	cmd.Dir = params.Dir
+
+	if err := cmd.Start(); err != nil {
+		log.Fatalf("%v", err)
+	}
+	msg.Suspend()
+
+	/*
+		close setup pipe
+	*/
+
+	if err := closeSetup(); err != nil {
+		log.Println("cannot close setup pipe:", err)
+		// not fatal
+	}
+
+	/*
+		perform init duties
+	*/
+
+	sig := make(chan os.Signal, 2)
+	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+
+	type winfo struct {
+		wpid    int
+		wstatus syscall.WaitStatus
+	}
+	info := make(chan winfo, 1)
+	done := make(chan struct{})
+
+	go func() {
+		var (
+			err     error
+			wpid    = -2
+			wstatus syscall.WaitStatus
+		)
+
+		// keep going until no child process is left
+		for wpid != -1 {
+			if err != nil {
+				break
+			}
+
+			if wpid != -2 {
+				info <- winfo{wpid, wstatus}
+			}
+
+			err = syscall.EINTR
+			for errors.Is(err, syscall.EINTR) {
+				wpid, err = syscall.Wait4(-1, &wstatus, 0, nil)
+			}
+		}
+		if !errors.Is(err, syscall.ECHILD) {
+			log.Println("unexpected wait4 response:", err)
+		}
+
+		close(done)
+	}()
+
+	// closed after residualProcessTimeout has elapsed after initial process death
+	timeout := make(chan struct{})
+
+	r := 2
+	for {
+		select {
+		case s := <-sig:
+			if msg.Resume() {
+				msg.Verbosef("terminating on %s after process start", s.String())
+			} else {
+				msg.Verbosef("terminating on %s", s.String())
+			}
+			msg.BeforeExit()
+			os.Exit(0)
+		case w := <-info:
+			if w.wpid == cmd.Process.Pid {
+				// initial process exited, output is most likely available again
+				msg.Resume()
+
+				switch {
+				case w.wstatus.Exited():
+					r = w.wstatus.ExitStatus()
+					msg.Verbosef("initial process exited with code %d", w.wstatus.ExitStatus())
+				case w.wstatus.Signaled():
+					r = 128 + int(w.wstatus.Signal())
+					msg.Verbosef("initial process exited with signal %s", w.wstatus.Signal())
+				default:
+					r = 255
+					msg.Verbosef("initial process exited with status %#x", w.wstatus)
+				}
+
+				go func() {
+					time.Sleep(residualProcessTimeout)
+					close(timeout)
+				}()
+			}
+		case <-done:
+			msg.BeforeExit()
+			os.Exit(r)
+		case <-timeout:
+			log.Println("timeout exceeded waiting for lingering processes")
+			msg.BeforeExit()
+			os.Exit(r)
+		}
+	}
+}
+
+// TryArgv0 calls [Init] if the last element of argv0 is "init".
+func TryArgv0(v Msg, prepare func(prefix string), setVerbose func(verbose bool)) {
+	if len(os.Args) > 0 && path.Base(os.Args[0]) == "init" {
+		msg = v
+		Init(prepare, setVerbose)
+		msg.BeforeExit()
+		os.Exit(0)
+	}
+}

sandbox/mount.go

@@ -0,0 +1,125 @@
+package sandbox
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+func (p *procPaths) bindMount(source, target string, flags uintptr, eq bool) error {
+	if eq {
+		msg.Verbosef("resolved %q flags %#x", target, flags)
+	} else {
+		msg.Verbosef("resolved %q on %q flags %#x", source, target, flags)
+	}
+
+	if err := syscall.Mount(source, target, "",
+		syscall.MS_SILENT|syscall.MS_BIND|flags&syscall.MS_REC, ""); err != nil {
+		return wrapErrSuffix(err,
+			fmt.Sprintf("cannot mount %q on %q:", source, target))
+	}
+
+	var targetFinal string
+	if v, err := filepath.EvalSymlinks(target); err != nil {
+		return wrapErrSelf(err)
+	} else {
+		targetFinal = v
+		if targetFinal != target {
+			msg.Verbosef("target resolves to %q", targetFinal)
+		}
+	}
+
+	// final target path according to the kernel through proc
+	var targetKFinal string
+	{
+		var destFd int
+		if err := IgnoringEINTR(func() (err error) {
+			destFd, err = syscall.Open(targetFinal, O_PATH|syscall.O_CLOEXEC, 0)
+			return
+		}); err != nil {
+			return wrapErrSuffix(err,
+				fmt.Sprintf("cannot open %q:", targetFinal))
+		}
+		if v, err := os.Readlink(p.fd(destFd)); err != nil {
+			return wrapErrSelf(err)
+		} else if err = syscall.Close(destFd); err != nil {
+			return wrapErrSuffix(err,
+				fmt.Sprintf("cannot close %q:", targetFinal))
+		} else {
+			targetKFinal = v
+		}
+	}
+
+	mf := syscall.MS_NOSUID | flags&syscall.MS_NODEV | flags&syscall.MS_RDONLY
+	return hostProc.mountinfo(func(d *vfs.MountInfoDecoder) error {
+		n, err := d.Unfold(targetKFinal)
+		if err != nil {
+			if errors.Is(err, syscall.ESTALE) {
+				return msg.WrapErr(err,
+					fmt.Sprintf("mount point %q never appeared in mountinfo", targetKFinal))
+			}
+			return wrapErrSuffix(err,
+				"cannot unfold mount hierarchy:")
+		}
+
+		if err = remountWithFlags(n, mf); err != nil {
+			return err
+		}
+		if flags&syscall.MS_REC == 0 {
+			return nil
+		}
+
+		for cur := range n.Collective() {
+			err = remountWithFlags(cur, mf)
+			if err != nil && !errors.Is(err, syscall.EACCES) {
+				return err
+			}
+		}
+
+		return nil
+	})
+}
+
+func remountWithFlags(n *vfs.MountInfoNode, mf uintptr) error {
+	kf, unmatched := n.Flags()
+	if len(unmatched) != 0 {
+		msg.Verbosef("unmatched vfs options: %q", unmatched)
+	}
+
+	if kf&mf != mf {
+		return wrapErrSuffix(syscall.Mount("none", n.Clean, "",
+			syscall.MS_SILENT|syscall.MS_BIND|syscall.MS_REMOUNT|kf|mf,
+			""),
+			fmt.Sprintf("cannot remount %q:", n.Clean))
+	}
+	return nil
+}
+
+func mountTmpfs(fsname, name string, size int, perm os.FileMode) error {
+	target := toSysroot(name)
+	if err := os.MkdirAll(target, parentPerm(perm)); err != nil {
+		return wrapErrSelf(err)
+	}
+	opt := fmt.Sprintf("mode=%#o", perm)
+	if size > 0 {
+		opt += fmt.Sprintf(",size=%d", size)
+	}
+	return wrapErrSuffix(syscall.Mount(fsname, target, "tmpfs",
+		syscall.MS_NOSUID|syscall.MS_NODEV, opt),
+		fmt.Sprintf("cannot mount tmpfs on %q:", name))
+}
+
+func parentPerm(perm os.FileMode) os.FileMode {
+	pperm := 0755
+	if perm&0070 == 0 {
+		pperm &= ^0050
+	}
+	if perm&0007 == 0 {
+		pperm &= ^0005
+	}
+	return os.FileMode(pperm)
+}

sandbox/msg.go

@@ -0,0 +1,43 @@
+package sandbox
+
+import (
+	"log"
+	"sync/atomic"
+)
+
+type Msg interface {
+	IsVerbose() bool
+	Verbose(v ...any)
+	Verbosef(format string, v ...any)
+	WrapErr(err error, a ...any) error
+	PrintBaseErr(err error, fallback string)
+
+	Suspend()
+	Resume() bool
+
+	BeforeExit()
+}
+
+type DefaultMsg struct{ inactive atomic.Bool }
+
+func (msg *DefaultMsg) IsVerbose() bool { return true }
+func (msg *DefaultMsg) Verbose(v ...any) {
+	if !msg.inactive.Load() {
+		log.Println(v...)
+	}
+}
+func (msg *DefaultMsg) Verbosef(format string, v ...any) {
+	if !msg.inactive.Load() {
+		log.Printf(format, v...)
+	}
+}
+
+func (msg *DefaultMsg) WrapErr(err error, a ...any) error {
+	log.Println(a...)
+	return err
+}
+func (msg *DefaultMsg) PrintBaseErr(err error, fallback string) { log.Println(fallback, err) }
+
+func (msg *DefaultMsg) Suspend()     { msg.inactive.Store(true) }
+func (msg *DefaultMsg) Resume() bool { return msg.inactive.CompareAndSwap(true, false) }
+func (msg *DefaultMsg) BeforeExit()  {}

sandbox/output.go

@@ -0,0 +1,26 @@
+package sandbox
+
+var msg Msg = new(DefaultMsg)
+
+func GetOutput() Msg { return msg }
+func SetOutput(v Msg) {
+	if v == nil {
+		msg = new(DefaultMsg)
+	} else {
+		msg = v
+	}
+}
+
+func wrapErrSuffix(err error, a ...any) error {
+	if err == nil {
+		return nil
+	}
+	return msg.WrapErr(err, append(a, err)...)
+}
+
+func wrapErrSelf(err error) error {
+	if err == nil {
+		return nil
+	}
+	return msg.WrapErr(err, err.Error())
+}

sandbox/params.go

@@ -1,4 +1,4 @@
-package proc
+package sandbox
 
 import (
 	"encoding/gob"
@@ -12,7 +12,7 @@ var (
 	ErrInvalid = errors.New("bad file descriptor")
 )
 
-// Setup appends the read end of a pipe for payload transmission and returns its fd.
+// Setup appends the read end of a pipe for setup params transmission and returns its fd.
 func Setup(extraFiles *[]*os.File) (int, *gob.Encoder, error) {
 	if r, w, err := os.Pipe(); err != nil {
 		return -1, nil, err
@@ -23,9 +23,8 @@ func Setup(extraFiles *[]*os.File) (int, *gob.Encoder, error) {
 	}
 }
 
-// Receive retrieves payload pipe fd from the environment,
-// receives its payload and returns the Close method of the pipe.
-func Receive(key string, e any) (func() error, error) {
+// Receive retrieves setup fd from the environment and receives params.
+func Receive(key string, e any, v **os.File) (func() error, error) {
 	var setup *os.File
 
 	if s, ok := os.LookupEnv(key); !ok {
@@ -38,8 +37,11 @@ func Receive(key string, e any) (func() error, error) {
 			if setup == nil {
 				return nil, ErrInvalid
 			}
+			if v != nil {
+				*v = setup
+			}
 		}
 	}
 
-	return func() error { return setup.Close() }, gob.NewDecoder(setup).Decode(e)
+	return setup.Close, gob.NewDecoder(setup).Decode(e)
 }

sandbox/path.go

@@ -0,0 +1,94 @@
+package sandbox
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+const (
+	hostPath    = "/" + hostDir
+	hostDir     = "host"
+	sysrootPath = "/" + sysrootDir
+	sysrootDir  = "sysroot"
+)
+
+func toSysroot(name string) string {
+	name = strings.TrimLeftFunc(name, func(r rune) bool { return r == '/' })
+	return path.Join(sysrootPath, name)
+}
+
+func toHost(name string) string {
+	name = strings.TrimLeftFunc(name, func(r rune) bool { return r == '/' })
+	return path.Join(hostPath, name)
+}
+
+func createFile(name string, perm, pperm os.FileMode, content []byte) error {
+	if err := os.MkdirAll(path.Dir(name), pperm); err != nil {
+		return wrapErrSelf(err)
+	}
+	f, err := os.OpenFile(name, syscall.O_CREAT|syscall.O_EXCL|syscall.O_WRONLY, perm)
+	if err != nil {
+		return wrapErrSelf(err)
+	}
+	if content != nil {
+		_, err = f.Write(content)
+		if err != nil {
+			err = wrapErrSelf(err)
+		}
+	}
+	return errors.Join(f.Close(), err)
+}
+
+func ensureFile(name string, perm, pperm os.FileMode) error {
+	fi, err := os.Stat(name)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+		return createFile(name, perm, pperm, nil)
+	}
+
+	if mode := fi.Mode(); mode&fs.ModeDir != 0 || mode&fs.ModeSymlink != 0 {
+		err = msg.WrapErr(syscall.EISDIR,
+			fmt.Sprintf("path %q is a directory", name))
+	}
+	return err
+}
+
+var hostProc = newProcPats(hostPath)
+
+func newProcPats(prefix string) *procPaths {
+	return &procPaths{prefix + "/proc", prefix + "/proc/self"}
+}
+
+type procPaths struct {
+	prefix string
+	self   string
+}
+
+func (p *procPaths) stdout() string   { return p.self + "/fd/1" }
+func (p *procPaths) fd(fd int) string { return p.self + "/fd/" + strconv.Itoa(fd) }
+func (p *procPaths) mountinfo(f func(d *vfs.MountInfoDecoder) error) error {
+	if r, err := os.Open(p.self + "/mountinfo"); err != nil {
+		return wrapErrSelf(err)
+	} else {
+		d := vfs.NewMountInfoDecoder(r)
+		err0 := f(d)
+		if err = r.Close(); err != nil {
+			return wrapErrSuffix(err,
+				"cannot close mountinfo:")
+		} else if err = d.Err(); err != nil {
+			return wrapErrSuffix(err,
+				"cannot parse mountinfo:")
+		}
+		return err0
+	}
+}

sandbox/seccomp/api.go

@@ -11,6 +11,9 @@ import (
 // New returns an inactive Encoder instance.
 func New(opts SyscallOpts) *Encoder { return &Encoder{newExporter(opts)} }
 
+// Load loads a filter into the kernel.
+func Load(opts SyscallOpts) error { return buildFilter(-1, opts) }
+
 /*
 An Encoder writes a BPF program to an output stream.
 

sandbox/seccomp/export.go

@@ -28,7 +28,7 @@ func (e *exporter) prepare() error {
 
 		ec := make(chan error, 1)
 		go func(fd uintptr) {
-			ec <- exportFilter(fd, e.opts)
+			ec <- buildFilter(int(fd), e.opts)
 			close(ec)
 			_ = e.closeWrite()
 			runtime.KeepAlive(e.w)

sandbox/seccomp/export_test.go

@@ -4,12 +4,11 @@ import (
 	"crypto/sha512"
 	"errors"
 	"io"
-	"log"
 	"slices"
 	"syscall"
 	"testing"
 
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
 )
 
 func TestExport(t *testing.T) {
@@ -79,8 +78,9 @@ func TestExport(t *testing.T) {
 	buf := make([]byte, 8)
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			seccomp.CPrintln = log.Println
-			t.Cleanup(func() { seccomp.CPrintln = nil })
+			oldF := seccomp.GetOutput()
+			seccomp.SetOutput(t.Log)
+			t.Cleanup(func() { seccomp.SetOutput(oldF) })
 
 			e := seccomp.New(tc.opts)
 			digest := sha512.New()
@@ -93,7 +93,7 @@ func TestExport(t *testing.T) {
 				t.Errorf("Close: error = %v", err)
 				return
 			}
-			if got := digest.Sum(nil); slices.Compare(got, tc.want) != 0 {
+			if got := digest.Sum(nil); !slices.Equal(got, tc.want) {
 				t.Fatalf("Export() hash = %x, want %x",
 					got, tc.want)
 				return
@@ -111,11 +111,14 @@ func TestExport(t *testing.T) {
 
 	t.Run("close partial read", func(t *testing.T) {
 		e := seccomp.New(0)
-		if _, err := e.Read(make([]byte, 0)); err != nil {
+		if _, err := e.Read(nil); err != nil {
 			t.Errorf("Read: error = %v", err)
 			return
 		}
-		if err := e.Close(); err == nil || err.Error() != "seccomp_export_bpf failed: operation canceled" {
+		// the underlying implementation uses buffered io, so the outcome of this is nondeterministic;
+		// that is not harmful however, so both outcomes are checked for here
+		if err := e.Close(); err != nil &&
+			(!errors.Is(err, syscall.ECANCELED) || !errors.Is(err, syscall.EBADF)) {
 			t.Errorf("Close: error = %v", err)
 			return
 		}

sandbox/seccomp/output.go

@@ -0,0 +1,30 @@
+package seccomp
+
+import "C"
+import "sync/atomic"
+
+var printlnP atomic.Pointer[func(v ...any)]
+
+func SetOutput(f func(v ...any)) {
+	if f == nil {
+		// avoid storing nil function
+		printlnP.Store(nil)
+	} else {
+		printlnP.Store(&f)
+	}
+}
+
+func GetOutput() func(v ...any) {
+	if fp := printlnP.Load(); fp == nil {
+		return nil
+	} else {
+		return *fp
+	}
+}
+
+//export F_println
+func F_println(v *C.char) {
+	if fp := printlnP.Load(); fp != nil {
+		(*fp)(C.GoString(v))
+	}
+}

sandbox/seccomp/seccomp-build.c

@@ -2,7 +2,7 @@
 #define _GNU_SOURCE // CLONE_NEWUSER
 #endif
 
-#include "seccomp-export.h"
+#include "seccomp-build.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <assert.h>
@@ -27,28 +27,27 @@ struct f_syscall_act {
 
 #define LEN(arr) (sizeof(arr) / sizeof((arr)[0]))
 
-#define SECCOMP_RULESET_ADD(ruleset) do {                                                                      \
-  if (opts & F_VERBOSE) F_println("adding seccomp ruleset \"" #ruleset "\"");                                  \
-  for (int i = 0; i < LEN(ruleset); i++) {                                                                     \
-    assert(ruleset[i].m_errno == EPERM || ruleset[i].m_errno == ENOSYS);                                       \
-                                                                                                               \
-    if (ruleset[i].arg)                                                                                        \
-      ret = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ruleset[i].m_errno), ruleset[i].syscall, 1, *ruleset[i].arg); \
-    else                                                                                                       \
-      ret = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ruleset[i].m_errno), ruleset[i].syscall, 0);                  \
-                                                                                                               \
-    if (ret == -EFAULT) {                                                                                      \
-      res = 4;                                                                                                 \
-      goto out;                                                                                                \
-    } else if (ret < 0) {                                                                                      \
-      res = 5;                                                                                                 \
-      errno = -ret;                                                                                            \
-      goto out;                                                                                                \
-    }                                                                                                          \
-  }                                                                                                            \
+#define SECCOMP_RULESET_ADD(ruleset) do {                                                                         \
+  if (opts & F_VERBOSE) F_println("adding seccomp ruleset \"" #ruleset "\"");                                     \
+  for (int i = 0; i < LEN(ruleset); i++) {                                                                        \
+    assert(ruleset[i].m_errno == EPERM || ruleset[i].m_errno == ENOSYS);                                          \
+                                                                                                                  \
+    if (ruleset[i].arg)                                                                                           \
+      *ret_p = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ruleset[i].m_errno), ruleset[i].syscall, 1, *ruleset[i].arg); \
+    else                                                                                                          \
+      *ret_p = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ruleset[i].m_errno), ruleset[i].syscall, 0);                  \
+                                                                                                                  \
+    if (*ret_p == -EFAULT) {                                                                                      \
+      res = 4;                                                                                                    \
+      goto out;                                                                                                   \
+    } else if (*ret_p < 0) {                                                                                      \
+      res = 5;                                                                                                    \
+      goto out;                                                                                                   \
+    }                                                                                                             \
+  }                                                                                                               \
 } while (0)
 
-int32_t f_export_bpf(int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts opts) {
+int32_t f_build_filter(int *ret_p, int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts opts) {
   int32_t res = 0; // refer to resErr for meaning
   int allow_multiarch = opts & F_MULTIARCH;
   int allowed_personality = PER_LINUX;
@@ -229,8 +228,6 @@ int32_t f_export_bpf(int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts o
   } else
     errno = 0;
 
-  int ret;
-
   // We only really need to handle arches on multiarch systems.
   // If only one arch is supported the default is fine
   if (arch != 0) {
@@ -239,18 +236,16 @@ int32_t f_export_bpf(int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts o
     // allow the target arch, but we can't really disallow the
     // native arch at this point, because then bubblewrap
     // couldn't continue running.
-    ret = seccomp_arch_add(ctx, arch);
-    if (ret < 0 && ret != -EEXIST) {
+    *ret_p = seccomp_arch_add(ctx, arch);
+    if (*ret_p < 0 && *ret_p != -EEXIST) {
       res = 2;
-      errno = -ret;
       goto out;
     }
 
     if (allow_multiarch && multiarch != 0) {
-      ret = seccomp_arch_add(ctx, multiarch);
-      if (ret < 0 && ret != -EEXIST) {
+      *ret_p = seccomp_arch_add(ctx, multiarch);
+      if (*ret_p < 0 && *ret_p != -EEXIST) {
         res = 3;
-        errno = -ret;
         goto out;
       }
     }
@@ -285,11 +280,18 @@ int32_t f_export_bpf(int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts o
   // Blocklist the rest
   seccomp_rule_add_exact(ctx, SCMP_ACT_ERRNO(EAFNOSUPPORT), SCMP_SYS(socket), 1, SCMP_A0(SCMP_CMP_GE, last_allowed_family + 1));
 
-  ret = seccomp_export_bpf(ctx, fd);
-  if (ret != 0) {
-    res = 6;
-    errno = -ret;
-    goto out;
+  if (fd < 0) {
+    *ret_p = seccomp_load(ctx);
+    if (*ret_p != 0) {
+      res = 7;
+      goto out;
+    }
+  } else {
+    *ret_p = seccomp_export_bpf(ctx, fd);
+    if (*ret_p != 0) {
+      res = 6;
+      goto out;
+    }
   }
 
 out:

sandbox/seccomp/seccomp-build.h

@@ -20,4 +20,4 @@ typedef enum {
 } f_syscall_opts;
 
 extern void F_println(char *v);
-int32_t f_export_bpf(int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts opts);
+int32_t f_build_filter(int *ret_p, int fd, uint32_t arch, uint32_t multiarch, f_syscall_opts opts);

sandbox/seccomp/seccomp.go

@@ -3,25 +3,56 @@ package seccomp
 /*
 #cgo linux pkg-config: --static libseccomp
 
-#include "seccomp-export.h"
+#include "seccomp-build.h"
 */
 import "C"
 import (
 	"errors"
 	"fmt"
 	"runtime"
+	"syscall"
 )
 
-var CPrintln func(v ...any)
+// LibraryError represents a libseccomp error.
+type LibraryError struct {
+	Prefix  string
+	Seccomp syscall.Errno
+	Errno   error
+}
 
-var resErr = [...]error{
-	0: nil,
-	1: errors.New("seccomp_init failed"),
-	2: errors.New("seccomp_arch_add failed"),
-	3: errors.New("seccomp_arch_add failed (multiarch)"),
-	4: errors.New("internal libseccomp failure"),
-	5: errors.New("seccomp_rule_add failed"),
-	6: errors.New("seccomp_export_bpf failed"),
+func (e *LibraryError) Error() string {
+	if e.Seccomp == 0 {
+		if e.Errno == nil {
+			panic("invalid libseccomp error")
+		}
+		return fmt.Sprintf("%s: %s", e.Prefix, e.Errno)
+	}
+	if e.Errno == nil {
+		return fmt.Sprintf("%s: %s", e.Prefix, e.Seccomp)
+	}
+	return fmt.Sprintf("%s: %s (%s)", e.Prefix, e.Seccomp, e.Errno)
+}
+
+func (e *LibraryError) Is(err error) bool {
+	if e == nil {
+		return err == nil
+	}
+	if ef, ok := err.(*LibraryError); ok {
+		return *e == *ef
+	}
+	return (e.Seccomp != 0 && errors.Is(err, e.Seccomp)) ||
+		(e.Errno != nil && errors.Is(err, e.Errno))
+}
+
+var resPrefix = [...]string{
+	0: "",
+	1: "seccomp_init failed",
+	2: "seccomp_arch_add failed",
+	3: "seccomp_arch_add failed (multiarch)",
+	4: "internal libseccomp failure",
+	5: "seccomp_rule_add failed",
+	6: "seccomp_export_bpf failed",
+	7: "seccomp_load failed",
 }
 
 type SyscallOpts = C.f_syscall_opts
@@ -46,7 +77,7 @@ const (
 	FlagBluetooth SyscallOpts = C.F_BLUETOOTH
 )
 
-func exportFilter(fd uintptr, opts SyscallOpts) error {
+func buildFilter(fd int, opts SyscallOpts) error {
 	var (
 		arch      C.uint32_t = 0
 		multiarch C.uint32_t = 0
@@ -66,23 +97,18 @@ func exportFilter(fd uintptr, opts SyscallOpts) error {
 
 	// this removes repeated transitions between C and Go execution
 	// when producing log output via F_println and CPrintln is nil
-	if CPrintln != nil {
+	if fp := printlnP.Load(); fp != nil {
 		opts |= flagVerbose
 	}
 
-	res, err := C.f_export_bpf(C.int(fd), arch, multiarch, opts)
-	if re := resErr[res]; re != nil {
-		if err == nil {
-			return re
+	var ret C.int
+	res, err := C.f_build_filter(&ret, C.int(fd), arch, multiarch, opts)
+	if prefix := resPrefix[res]; prefix != "" {
+		return &LibraryError{
+			prefix,
+			-syscall.Errno(ret),
+			err,
 		}
-		return fmt.Errorf("%s: %v", re.Error(), err)
 	}
 	return err
 }
-
-//export F_println
-func F_println(v *C.char) {
-	if CPrintln != nil {
-		CPrintln(C.GoString(v))
-	}
-}

sandbox/seccomp/seccomp_test.go

@@ -0,0 +1,65 @@
+package seccomp_test
+
+import (
+	"errors"
+	"runtime"
+	"syscall"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+)
+
+func TestLibraryError(t *testing.T) {
+	testCases := []struct {
+		name    string
+		sample  *seccomp.LibraryError
+		want    string
+		wantIs  bool
+		compare error
+	}{
+		{
+			"full",
+			&seccomp.LibraryError{Prefix: "seccomp_export_bpf failed", Seccomp: syscall.ECANCELED, Errno: syscall.EBADF},
+			"seccomp_export_bpf failed: operation canceled (bad file descriptor)",
+			true,
+			&seccomp.LibraryError{Prefix: "seccomp_export_bpf failed", Seccomp: syscall.ECANCELED, Errno: syscall.EBADF},
+		},
+		{
+			"errno only",
+			&seccomp.LibraryError{Prefix: "seccomp_init failed", Errno: syscall.ENOMEM},
+			"seccomp_init failed: cannot allocate memory",
+			false,
+			nil,
+		},
+		{
+			"seccomp only",
+			&seccomp.LibraryError{Prefix: "internal libseccomp failure", Seccomp: syscall.EFAULT},
+			"internal libseccomp failure: bad address",
+			true,
+			syscall.EFAULT,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if errors.Is(tc.sample, tc.compare) != tc.wantIs {
+				t.Errorf("errors.Is(%#v, %#v) did not return %v",
+					tc.sample, tc.compare, tc.wantIs)
+			}
+
+			if got := tc.sample.Error(); got != tc.want {
+				t.Errorf("Error: %q, want %q",
+					got, tc.want)
+			}
+		})
+	}
+
+	t.Run("invalid", func(t *testing.T) {
+		wantPanic := "invalid libseccomp error"
+		defer func() {
+			if r := recover(); r != wantPanic {
+				t.Errorf("panic: %q, want %q", r, wantPanic)
+			}
+		}()
+		runtime.KeepAlive(new(seccomp.LibraryError).Error())
+	})
+}

sandbox/sequential.go

@@ -0,0 +1,426 @@
+package sandbox
+
+import (
+	"encoding/gob"
+	"fmt"
+	"math"
+	"os"
+	"path"
+	"path/filepath"
+	"slices"
+	"strings"
+	"syscall"
+	"unsafe"
+)
+
+func init() { gob.Register(new(BindMount)) }
+
+// BindMount bind mounts host path Source on container path Target.
+type BindMount struct {
+	Source, SourceFinal, Target string
+
+	Flags int
+}
+
+const (
+	BindOptional = 1 << iota
+	BindWritable
+	BindDevice
+)
+
+func (b *BindMount) early(*Params) error {
+	if !path.IsAbs(b.Source) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", b.Source))
+	}
+
+	if v, err := filepath.EvalSymlinks(b.Source); err != nil {
+		if os.IsNotExist(err) && b.Flags&BindOptional != 0 {
+			b.SourceFinal = "\x00"
+			return nil
+		}
+		return wrapErrSelf(err)
+	} else {
+		b.SourceFinal = v
+		return nil
+	}
+}
+
+func (b *BindMount) apply(*Params) error {
+	if b.SourceFinal == "\x00" {
+		if b.Flags&BindOptional == 0 {
+			// unreachable
+			return syscall.EBADE
+		}
+		return nil
+	}
+
+	if !path.IsAbs(b.SourceFinal) || !path.IsAbs(b.Target) {
+		return msg.WrapErr(syscall.EBADE,
+			"path is not absolute")
+	}
+
+	source := toHost(b.SourceFinal)
+	target := toSysroot(b.Target)
+
+	// this perm value emulates bwrap behaviour as it clears bits from 0755 based on
+	// op->perms which is never set for any bind setup op so always results in 0700
+	if fi, err := os.Stat(source); err != nil {
+		return wrapErrSelf(err)
+	} else if fi.IsDir() {
+		if err = os.MkdirAll(target, 0700); err != nil {
+			return wrapErrSelf(err)
+		}
+	} else if err = ensureFile(target, 0444, 0700); err != nil {
+		return err
+	}
+
+	var flags uintptr = syscall.MS_REC
+	if b.Flags&BindWritable == 0 {
+		flags |= syscall.MS_RDONLY
+	}
+	if b.Flags&BindDevice == 0 {
+		flags |= syscall.MS_NODEV
+	}
+
+	return hostProc.bindMount(source, target, flags, b.SourceFinal == b.Target)
+}
+
+func (b *BindMount) Is(op Op) bool { vb, ok := op.(*BindMount); return ok && *b == *vb }
+func (*BindMount) prefix() string  { return "mounting" }
+func (b *BindMount) String() string {
+	if b.Source == b.Target {
+		return fmt.Sprintf("%q flags %#x", b.Source, b.Flags)
+	}
+	return fmt.Sprintf("%q on %q flags %#x", b.Source, b.Target, b.Flags&BindWritable)
+}
+func (f *Ops) Bind(source, target string, flags int) *Ops {
+	*f = append(*f, &BindMount{source, "", target, flags})
+	return f
+}
+
+func init() { gob.Register(new(MountProc)) }
+
+// MountProc mounts a private instance of proc.
+type MountProc string
+
+func (p MountProc) early(*Params) error { return nil }
+func (p MountProc) apply(params *Params) error {
+	v := string(p)
+
+	if !path.IsAbs(v) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", v))
+	}
+
+	target := toSysroot(v)
+	if err := os.MkdirAll(target, params.ParentPerm); err != nil {
+		return wrapErrSelf(err)
+	}
+	return wrapErrSuffix(syscall.Mount("proc", target, "proc",
+		syscall.MS_NOSUID|syscall.MS_NOEXEC|syscall.MS_NODEV, ""),
+		fmt.Sprintf("cannot mount proc on %q:", v))
+}
+
+func (p MountProc) Is(op Op) bool  { vp, ok := op.(MountProc); return ok && p == vp }
+func (MountProc) prefix() string   { return "mounting" }
+func (p MountProc) String() string { return fmt.Sprintf("proc on %q", string(p)) }
+func (f *Ops) Proc(dest string) *Ops {
+	*f = append(*f, MountProc(dest))
+	return f
+}
+
+func init() { gob.Register(new(MountDev)) }
+
+// MountDev mounts part of host dev.
+type MountDev string
+
+func (d MountDev) early(*Params) error { return nil }
+func (d MountDev) apply(params *Params) error {
+	v := string(d)
+
+	if !path.IsAbs(v) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", v))
+	}
+	target := toSysroot(v)
+
+	if err := mountTmpfs("devtmpfs", v, 0, params.ParentPerm); err != nil {
+		return err
+	}
+
+	for _, name := range []string{"null", "zero", "full", "random", "urandom", "tty"} {
+		targetPath := toSysroot(path.Join(v, name))
+		if err := ensureFile(targetPath, 0444, params.ParentPerm); err != nil {
+			return err
+		}
+		if err := hostProc.bindMount(
+			toHost("/dev/"+name),
+			targetPath,
+			0,
+			true,
+		); err != nil {
+			return err
+		}
+	}
+	for i, name := range []string{"stdin", "stdout", "stderr"} {
+		if err := os.Symlink(
+			"/proc/self/fd/"+string(rune(i+'0')),
+			path.Join(target, name),
+		); err != nil {
+			return wrapErrSelf(err)
+		}
+	}
+	for _, pair := range [][2]string{
+		{"/proc/self/fd", "fd"},
+		{"/proc/kcore", "core"},
+		{"pts/ptmx", "ptmx"},
+	} {
+		if err := os.Symlink(pair[0], path.Join(target, pair[1])); err != nil {
+			return wrapErrSelf(err)
+		}
+	}
+
+	devPtsPath := path.Join(target, "pts")
+	for _, name := range []string{path.Join(target, "shm"), devPtsPath} {
+		if err := os.Mkdir(name, params.ParentPerm); err != nil {
+			return wrapErrSelf(err)
+		}
+	}
+
+	if err := syscall.Mount("devpts", devPtsPath, "devpts",
+		syscall.MS_NOSUID|syscall.MS_NOEXEC,
+		"newinstance,ptmxmode=0666,mode=620"); err != nil {
+		return wrapErrSuffix(err,
+			fmt.Sprintf("cannot mount devpts on %q:", devPtsPath))
+	}
+
+	if params.Flags&FAllowTTY != 0 {
+		var buf [8]byte
+		if _, _, errno := syscall.Syscall(
+			syscall.SYS_IOCTL, 1, syscall.TIOCGWINSZ,
+			uintptr(unsafe.Pointer(&buf[0])),
+		); errno == 0 {
+			consolePath := toSysroot(path.Join(v, "console"))
+			if err := ensureFile(consolePath, 0444, params.ParentPerm); err != nil {
+				return err
+			}
+			if name, err := os.Readlink(hostProc.stdout()); err != nil {
+				return wrapErrSelf(err)
+			} else if err = hostProc.bindMount(
+				toHost(name),
+				consolePath,
+				0,
+				false,
+			); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func (d MountDev) Is(op Op) bool  { vd, ok := op.(MountDev); return ok && d == vd }
+func (MountDev) prefix() string   { return "mounting" }
+func (d MountDev) String() string { return fmt.Sprintf("dev on %q", string(d)) }
+func (f *Ops) Dev(dest string) *Ops {
+	*f = append(*f, MountDev(dest))
+	return f
+}
+
+func init() { gob.Register(new(MountMqueue)) }
+
+// MountMqueue mounts a private mqueue instance on container Path.
+type MountMqueue string
+
+func (m MountMqueue) early(*Params) error { return nil }
+func (m MountMqueue) apply(params *Params) error {
+	v := string(m)
+
+	if !path.IsAbs(v) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", v))
+	}
+
+	target := toSysroot(v)
+	if err := os.MkdirAll(target, params.ParentPerm); err != nil {
+		return wrapErrSelf(err)
+	}
+	return wrapErrSuffix(syscall.Mount("mqueue", target, "mqueue",
+		syscall.MS_NOSUID|syscall.MS_NOEXEC|syscall.MS_NODEV, ""),
+		fmt.Sprintf("cannot mount mqueue on %q:", v))
+}
+
+func (m MountMqueue) Is(op Op) bool  { vm, ok := op.(MountMqueue); return ok && m == vm }
+func (MountMqueue) prefix() string   { return "mounting" }
+func (m MountMqueue) String() string { return fmt.Sprintf("mqueue on %q", string(m)) }
+func (f *Ops) Mqueue(dest string) *Ops {
+	*f = append(*f, MountMqueue(dest))
+	return f
+}
+
+func init() { gob.Register(new(MountTmpfs)) }
+
+// MountTmpfs mounts tmpfs on container Path.
+type MountTmpfs struct {
+	Path string
+	Size int
+	Perm os.FileMode
+}
+
+func (t *MountTmpfs) early(*Params) error { return nil }
+func (t *MountTmpfs) apply(*Params) error {
+	if !path.IsAbs(t.Path) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", t.Path))
+	}
+	if t.Size < 0 || t.Size > math.MaxUint>>1 {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("size %d out of bounds", t.Size))
+	}
+	return mountTmpfs("tmpfs", t.Path, t.Size, t.Perm)
+}
+
+func (t *MountTmpfs) Is(op Op) bool  { vt, ok := op.(*MountTmpfs); return ok && *t == *vt }
+func (*MountTmpfs) prefix() string   { return "mounting" }
+func (t *MountTmpfs) String() string { return fmt.Sprintf("tmpfs on %q size %d", t.Path, t.Size) }
+func (f *Ops) Tmpfs(dest string, size int, perm os.FileMode) *Ops {
+	*f = append(*f, &MountTmpfs{dest, size, perm})
+	return f
+}
+
+func init() { gob.Register(new(Symlink)) }
+
+// Symlink creates a symlink in the container filesystem.
+type Symlink [2]string
+
+func (l *Symlink) early(*Params) error {
+	if strings.HasPrefix(l[0], "*") {
+		l[0] = l[0][1:]
+		if !path.IsAbs(l[0]) {
+			return msg.WrapErr(syscall.EBADE,
+				fmt.Sprintf("path %q is not absolute", l[0]))
+		}
+		if name, err := os.Readlink(l[0]); err != nil {
+			return wrapErrSelf(err)
+		} else {
+			l[0] = name
+		}
+	}
+	return nil
+}
+func (l *Symlink) apply(params *Params) error {
+	// symlink target is an arbitrary path value, so only validate link name here
+	if !path.IsAbs(l[1]) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", l[1]))
+	}
+
+	target := toSysroot(l[1])
+	if err := os.MkdirAll(path.Dir(target), params.ParentPerm); err != nil {
+		return wrapErrSelf(err)
+	}
+	if err := os.Symlink(l[0], target); err != nil {
+		return wrapErrSelf(err)
+	}
+	return nil
+}
+
+func (l *Symlink) Is(op Op) bool  { vl, ok := op.(*Symlink); return ok && *l == *vl }
+func (*Symlink) prefix() string   { return "creating" }
+func (l *Symlink) String() string { return fmt.Sprintf("symlink on %q target %q", l[1], l[0]) }
+func (f *Ops) Link(target, linkName string) *Ops {
+	*f = append(*f, &Symlink{target, linkName})
+	return f
+}
+
+func init() { gob.Register(new(Mkdir)) }
+
+// Mkdir creates a directory in the container filesystem.
+type Mkdir struct {
+	Path string
+	Perm os.FileMode
+}
+
+func (m *Mkdir) early(*Params) error { return nil }
+func (m *Mkdir) apply(*Params) error {
+	if !path.IsAbs(m.Path) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", m.Path))
+	}
+
+	if err := os.MkdirAll(toSysroot(m.Path), m.Perm); err != nil {
+		return wrapErrSelf(err)
+	}
+	return nil
+}
+
+func (m *Mkdir) Is(op Op) bool  { vm, ok := op.(*Mkdir); return ok && m == vm }
+func (*Mkdir) prefix() string   { return "creating" }
+func (m *Mkdir) String() string { return fmt.Sprintf("directory %q perm %s", m.Path, m.Perm) }
+func (f *Ops) Mkdir(dest string, perm os.FileMode) *Ops {
+	*f = append(*f, &Mkdir{dest, perm})
+	return f
+}
+
+func init() { gob.Register(new(Tmpfile)) }
+
+// Tmpfile places a file in container Path containing Data.
+type Tmpfile struct {
+	Path string
+	Data []byte
+}
+
+func (t *Tmpfile) early(*Params) error { return nil }
+func (t *Tmpfile) apply(params *Params) error {
+	if !path.IsAbs(t.Path) {
+		return msg.WrapErr(syscall.EBADE,
+			fmt.Sprintf("path %q is not absolute", t.Path))
+	}
+
+	var tmpPath string
+	if f, err := os.CreateTemp("/", "tmp.*"); err != nil {
+		return wrapErrSelf(err)
+	} else if _, err = f.Write(t.Data); err != nil {
+		return wrapErrSuffix(err,
+			"cannot write to intermediate file:")
+	} else if err = f.Close(); err != nil {
+		return wrapErrSuffix(err,
+			"cannot close intermediate file:")
+	} else {
+		tmpPath = f.Name()
+	}
+
+	target := toSysroot(t.Path)
+	if err := ensureFile(target, 0444, params.ParentPerm); err != nil {
+		return err
+	} else if err = hostProc.bindMount(
+		tmpPath,
+		target,
+		syscall.MS_RDONLY|syscall.MS_NODEV,
+		false,
+	); err != nil {
+		return err
+	} else if err = os.Remove(tmpPath); err != nil {
+		return wrapErrSelf(err)
+	}
+	return nil
+}
+
+func (t *Tmpfile) Is(op Op) bool {
+	vt, ok := op.(*Tmpfile)
+	return ok && t.Path == vt.Path && slices.Equal(t.Data, vt.Data)
+}
+func (*Tmpfile) prefix() string { return "placing" }
+func (t *Tmpfile) String() string {
+	return fmt.Sprintf("tmpfile %q (%d bytes)", t.Path, len(t.Data))
+}
+func (f *Ops) Place(name string, data []byte) *Ops { *f = append(*f, &Tmpfile{name, data}); return f }
+func (f *Ops) PlaceP(name string, dataP **[]byte) *Ops {
+	t := &Tmpfile{Path: name}
+	*dataP = &t.Data
+
+	*f = append(*f, t)
+	return f
+}

sandbox/syscall.go

@@ -0,0 +1,75 @@
+package sandbox
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+const (
+	O_PATH = 0x200000
+
+	PR_SET_NO_NEW_PRIVS = 0x26
+
+	CAP_SYS_ADMIN = 0x15
+)
+
+const (
+	SUID_DUMP_DISABLE = iota
+	SUID_DUMP_USER
+)
+
+func SetDumpable(dumpable uintptr) error {
+	// linux/sched/coredump.h
+	if _, _, errno := syscall.Syscall(syscall.SYS_PRCTL, syscall.PR_SET_DUMPABLE, dumpable, 0); errno != 0 {
+		return errno
+	}
+
+	return nil
+}
+
+const (
+	_LINUX_CAPABILITY_VERSION_3 = 0x20080522
+
+	PR_CAP_AMBIENT           = 47
+	PR_CAP_AMBIENT_CLEAR_ALL = 4
+
+	CAP_SETPCAP = 8
+)
+
+type (
+	capHeader struct {
+		version uint32
+		pid     int32
+	}
+
+	capData struct {
+		effective   uint32
+		permitted   uint32
+		inheritable uint32
+	}
+)
+
+func capset(hdrp *capHeader, datap *[2]capData) error {
+	if _, _, errno := syscall.Syscall(syscall.SYS_CAPSET,
+		uintptr(unsafe.Pointer(hdrp)),
+		uintptr(unsafe.Pointer(&datap[0])), 0); errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+// IgnoringEINTR makes a function call and repeats it if it returns an
+// EINTR error. This appears to be required even though we install all
+// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
+// Also #20400 and #36644 are issues in which a signal handler is
+// installed without setting SA_RESTART. None of these are the common case,
+// but there are enough of them that it seems that we can't avoid
+// an EINTR loop.
+func IgnoringEINTR(fn func() error) error {
+	for {
+		err := fn()
+		if err != syscall.EINTR {
+			return err
+		}
+	}
+}

sandbox/sysctl.go

@@ -0,0 +1,47 @@
+package sandbox
+
+import (
+	"bytes"
+	"log"
+	"os"
+	"strconv"
+	"sync"
+)
+
+var (
+	kernelOverflowuid int
+	kernelOverflowgid int
+	kernelCapLastCap  int
+
+	sysctlOnce sync.Once
+)
+
+const (
+	kernelOverflowuidPath = "/proc/sys/kernel/overflowuid"
+	kernelOverflowgidPath = "/proc/sys/kernel/overflowgid"
+	kernelCapLastCapPath  = "/proc/sys/kernel/cap_last_cap"
+)
+
+func mustReadSysctl() {
+	if v, err := os.ReadFile(kernelOverflowuidPath); err != nil {
+		log.Fatalf("cannot read %q: %v", kernelOverflowuidPath, err)
+	} else if kernelOverflowuid, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
+		log.Fatalf("cannot interpret %q: %v", kernelOverflowuidPath, err)
+	}
+
+	if v, err := os.ReadFile(kernelOverflowgidPath); err != nil {
+		log.Fatalf("cannot read %q: %v", kernelOverflowgidPath, err)
+	} else if kernelOverflowgid, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
+		log.Fatalf("cannot interpret %q: %v", kernelOverflowgidPath, err)
+	}
+
+	if v, err := os.ReadFile(kernelCapLastCapPath); err != nil {
+		log.Fatalf("cannot read %q: %v", kernelCapLastCapPath, err)
+	} else if kernelCapLastCap, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
+		log.Fatalf("cannot interpret %q: %v", kernelCapLastCapPath, err)
+	}
+}
+
+func OverflowUid() int { sysctlOnce.Do(mustReadSysctl); return kernelOverflowuid }
+func OverflowGid() int { sysctlOnce.Do(mustReadSysctl); return kernelOverflowgid }
+func LastCap() uintptr { sysctlOnce.Do(mustReadSysctl); return uintptr(kernelCapLastCap) }

sandbox/vfs/mangle.go

@@ -0,0 +1,30 @@
+package vfs
+
+import "strings"
+
+func Unmangle(s string) string {
+	if !strings.ContainsRune(s, '\\') {
+		return s
+	}
+
+	v := make([]byte, len(s))
+	var (
+		j int
+		c byte
+	)
+	for i := 0; i < len(s); i++ {
+		c = s[i]
+		if c == '\\' && len(s) > i+3 &&
+			(s[i+1] == '0' || s[i+1] == '1') &&
+			(s[i+2] >= '0' && s[i+2] <= '7') &&
+			(s[i+3] >= '0' && s[i+3] <= '7') {
+			c = ((s[i+1] - '0') << 6) |
+				((s[i+2] - '0') << 3) |
+				(s[i+3] - '0')
+			i += 3
+		}
+		v[j] = c
+		j++
+	}
+	return string(v[:j])
+}

sandbox/vfs/mangle_test.go

@@ -0,0 +1,27 @@
+package vfs_test
+
+import (
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+func TestUnmangle(t *testing.T) {
+	testCases := []struct {
+		want   string
+		sample string
+	}{
+		{`\, `, `\134\054\040`},
+		{`(10) source -- maybe empty string`, `(10)\040source\040--\040maybe empty string`},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.want, func(t *testing.T) {
+			got := vfs.Unmangle(tc.sample)
+			if got != tc.want {
+				t.Errorf("Unmangle: %q, want %q",
+					got, tc.want)
+			}
+		})
+	}
+}

sandbox/vfs/mountinfo.go

@@ -0,0 +1,260 @@
+// Package vfs provides bindings and iterators over proc_pid_mountinfo(5).
+package vfs
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"iter"
+	"slices"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+const (
+	MS_NOSYMFOLLOW = 0x100
+)
+
+var (
+	ErrMountInfoFields = errors.New("unexpected field count")
+	ErrMountInfoEmpty  = errors.New("unexpected empty field")
+	ErrMountInfoDevno  = errors.New("bad maj:min field")
+	ErrMountInfoSep    = errors.New("bad optional fields separator")
+)
+
+type (
+	// A MountInfoDecoder reads and decodes proc_pid_mountinfo(5) entries from an input stream.
+	MountInfoDecoder struct {
+		s *bufio.Scanner
+		m *MountInfo
+
+		current  *MountInfo
+		parseErr error
+		complete bool
+	}
+
+	// MountInfo represents the contents of a proc_pid_mountinfo(5) document.
+	MountInfo struct {
+		Next *MountInfo
+		MountInfoEntry
+	}
+
+	// MountInfoEntry represents a proc_pid_mountinfo(5) entry.
+	MountInfoEntry struct {
+		// mount ID: a unique ID for the mount (may be reused after umount(2)).
+		ID int `json:"id"`
+		// parent ID: the ID of the parent mount (or of self for the root of this mount namespace's mount tree).
+		Parent int `json:"parent"`
+		// major:minor: the value of st_dev for files on this filesystem (see stat(2)).
+		Devno DevT `json:"devno"`
+		// root: the pathname of the directory in the filesystem which forms the root of this mount.
+		Root string `json:"root"`
+		// mount point: the pathname of the mount point relative to the process's root directory.
+		Target string `json:"target"`
+		// mount options: per-mount options (see mount(2)).
+		VfsOptstr string `json:"vfs_optstr"`
+		// optional fields: zero or more fields of the form "tag[:value]"; see below.
+		// separator: the end of the optional fields is marked by a single hyphen.
+		OptFields []string `json:"opt_fields"`
+		// filesystem type: the filesystem type in the form "type[.subtype]".
+		FsType string `json:"fstype"`
+		// mount source: filesystem-specific information or "none".
+		Source string `json:"source"`
+		// super options: per-superblock options (see mount(2)).
+		FsOptstr string `json:"fs_optstr"`
+	}
+
+	DevT [2]int
+)
+
+// Flags interprets VfsOptstr and returns the resulting flags and unmatched options.
+func (e *MountInfoEntry) Flags() (flags uintptr, unmatched []string) {
+	for _, s := range strings.Split(e.VfsOptstr, ",") {
+		switch s {
+		case "rw":
+		case "ro":
+			flags |= syscall.MS_RDONLY
+		case "nosuid":
+			flags |= syscall.MS_NOSUID
+		case "nodev":
+			flags |= syscall.MS_NODEV
+		case "noexec":
+			flags |= syscall.MS_NOEXEC
+		case "nosymfollow":
+			flags |= MS_NOSYMFOLLOW
+		case "noatime":
+			flags |= syscall.MS_NOATIME
+		case "nodiratime":
+			flags |= syscall.MS_NODIRATIME
+		case "relatime":
+			flags |= syscall.MS_RELATIME
+		default:
+			unmatched = append(unmatched, s)
+		}
+	}
+	return
+}
+
+// NewMountInfoDecoder returns a new decoder that reads from r.
+//
+// The decoder introduces its own buffering and may read data from r beyond the mountinfo entries requested.
+func NewMountInfoDecoder(r io.Reader) *MountInfoDecoder {
+	return &MountInfoDecoder{s: bufio.NewScanner(r)}
+}
+
+func (d *MountInfoDecoder) Decode(v **MountInfo) (err error) {
+	for d.scan() {
+	}
+	err = d.Err()
+	if err == nil {
+		*v = d.m
+	}
+	return
+}
+
+// Entries returns an iterator over mountinfo entries.
+func (d *MountInfoDecoder) Entries() iter.Seq[*MountInfoEntry] {
+	return func(yield func(*MountInfoEntry) bool) {
+		for cur := d.m; cur != nil; cur = cur.Next {
+			if !yield(&cur.MountInfoEntry) {
+				return
+			}
+		}
+		for d.scan() {
+			if !yield(&d.current.MountInfoEntry) {
+				return
+			}
+		}
+	}
+}
+
+func (d *MountInfoDecoder) Err() error {
+	if err := d.s.Err(); err != nil {
+		return err
+	}
+	return d.parseErr
+}
+
+func (d *MountInfoDecoder) scan() bool {
+	if d.complete {
+		return false
+	}
+	if !d.s.Scan() {
+		d.complete = true
+		return false
+	}
+
+	m := new(MountInfo)
+	if err := parseMountInfoLine(d.s.Text(), &m.MountInfoEntry); err != nil {
+		d.parseErr = err
+		d.complete = true
+		return false
+	}
+
+	if d.current == nil {
+		d.m = m
+		d.current = d.m
+	} else {
+		d.current.Next = m
+		d.current = d.current.Next
+	}
+	return true
+}
+
+func parseMountInfoLine(s string, ent *MountInfoEntry) error {
+	// prevent proceeding with misaligned fields due to optional fields
+	f := strings.Split(s, " ")
+	if len(f) < 10 {
+		return ErrMountInfoFields
+	}
+
+	// 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
+	// (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
+
+	// (1) id
+	if id, err := strconv.Atoi(f[0]); err != nil { // 0
+		return err
+	} else {
+		ent.ID = id
+	}
+
+	// (2) parent
+	if parent, err := strconv.Atoi(f[1]); err != nil { // 1
+		return err
+	} else {
+		ent.Parent = parent
+	}
+
+	// (3) maj:min
+	if n, err := fmt.Sscanf(f[2], "%d:%d", &ent.Devno[0], &ent.Devno[1]); err != nil {
+		return err
+	} else if n != 2 {
+		// unreachable
+		return ErrMountInfoDevno
+	}
+
+	// (4) mountroot
+	ent.Root = Unmangle(f[3])
+	if ent.Root == "" {
+		return ErrMountInfoEmpty
+	}
+
+	// (5) target
+	ent.Target = Unmangle(f[4])
+	if ent.Target == "" {
+		return ErrMountInfoEmpty
+	}
+
+	// (6) vfs options (fs-independent)
+	ent.VfsOptstr = Unmangle(f[5])
+	if ent.VfsOptstr == "" {
+		return ErrMountInfoEmpty
+	}
+
+	// (7) optional fields, terminated by " - "
+	i := len(f) - 4
+	ent.OptFields = f[6:i]
+
+	// (8) optional fields end marker
+	if f[i] != "-" {
+		return ErrMountInfoSep
+	}
+	i++
+
+	// (9) FS type
+	ent.FsType = Unmangle(f[i])
+	if ent.FsType == "" {
+		return ErrMountInfoEmpty
+	}
+	i++
+
+	// (10) source -- maybe empty string
+	ent.Source = Unmangle(f[i])
+	i++
+
+	// (11) fs options (fs specific)
+	ent.FsOptstr = Unmangle(f[i])
+
+	return nil
+}
+
+func (e *MountInfoEntry) EqualWithIgnore(want *MountInfoEntry, ignore string) bool {
+	return (e.ID == want.ID || want.ID == -1) &&
+		(e.Parent == want.Parent || want.Parent == -1) &&
+		(e.Devno == want.Devno || (want.Devno[0] == -1 && want.Devno[1] == -1)) &&
+		(e.Root == want.Root || want.Root == ignore) &&
+		(e.Target == want.Target || want.Target == ignore) &&
+		(e.VfsOptstr == want.VfsOptstr || want.VfsOptstr == ignore) &&
+		(slices.Equal(e.OptFields, want.OptFields) || (len(want.OptFields) == 1 && want.OptFields[0] == ignore)) &&
+		(e.FsType == want.FsType || want.FsType == ignore) &&
+		(e.Source == want.Source || want.Source == ignore) &&
+		(e.FsOptstr == want.FsOptstr || want.FsOptstr == ignore)
+}
+
+func (e *MountInfoEntry) String() string {
+	return fmt.Sprintf("%d %d %d:%d %s %s %s %s %s %s %s",
+		e.ID, e.Parent, e.Devno[0], e.Devno[1], e.Root, e.Target, e.VfsOptstr,
+		strings.Join(append(e.OptFields, "-"), " "), e.FsType, e.Source, e.FsOptstr)
+}

sandbox/vfs/mountinfo_test.go

@@ -0,0 +1,404 @@
+package vfs_test
+
+import (
+	"encoding/json"
+	"errors"
+	"iter"
+	"path"
+	"reflect"
+	"slices"
+	"strconv"
+	"strings"
+	"syscall"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+func TestMountInfo(t *testing.T) {
+	testCases := []mountInfoTest{
+		{"count", sampleMountinfoBase + `
+21 20 0:53/ /mnt/test rw,relatime - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoFields, "", nil, nil, nil},
+
+		{"sep", sampleMountinfoBase + `
+21 20 0:53 / /mnt/test rw,relatime shared:212 _ tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoSep, "", nil, nil, nil},
+
+		{"id", sampleMountinfoBase + `
+id 20 0:53 / /mnt/test rw,relatime shared:212 - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			strconv.ErrSyntax, "", nil, nil, nil},
+
+		{"parent", sampleMountinfoBase + `
+21 parent 0:53 / /mnt/test rw,relatime shared:212 - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			strconv.ErrSyntax, "", nil, nil, nil},
+
+		{"devno", sampleMountinfoBase + `
+21 20 053 / /mnt/test rw,relatime shared:212 - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			nil, "unexpected EOF", nil, nil, nil},
+
+		{"maj", sampleMountinfoBase + `
+21 20 maj:53 / /mnt/test rw,relatime shared:212 - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			nil, "expected integer", nil, nil, nil},
+
+		{"min", sampleMountinfoBase + `
+21 20 0:min / /mnt/test rw,relatime shared:212 - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			nil, "expected integer", nil, nil, nil},
+
+		{"mountroot", sampleMountinfoBase + `
+21 20 0:53  /mnt/test rw,relatime - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoEmpty, "", nil, nil, nil},
+
+		{"target", sampleMountinfoBase + `
+21 20 0:53 /  rw,relatime - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoEmpty, "", nil, nil, nil},
+
+		{"vfs options", sampleMountinfoBase + `
+21 20 0:53 / /mnt/test  - tmpfs  rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoEmpty, "", nil, nil, nil},
+
+		{"FS type", sampleMountinfoBase + `
+21 20 0:53 / /mnt/test rw,relatime -   rw
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755`,
+			vfs.ErrMountInfoEmpty, "", nil, nil, nil},
+
+		{"base", sampleMountinfoBase, nil, "", []*wantMountInfo{
+			m(15, 20, 0, 3, "/", "/proc", "rw,relatime", o(), "proc", "/proc", "rw", syscall.MS_RELATIME, nil),
+			m(16, 20, 0, 15, "/", "/sys", "rw,relatime", o(), "sysfs", "/sys", "rw", syscall.MS_RELATIME, nil),
+			m(17, 20, 0, 5, "/", "/dev", "rw,relatime", o(), "devtmpfs", "udev", "rw,size=1983516k,nr_inodes=495879,mode=755", syscall.MS_RELATIME, nil),
+			m(18, 17, 0, 10, "/", "/dev/pts", "rw,relatime", o(), "devpts", "devpts", "rw,gid=5,mode=620,ptmxmode=000", syscall.MS_RELATIME, nil),
+			m(19, 17, 0, 16, "/", "/dev/shm", "rw,relatime", o(), "tmpfs", "tmpfs", "rw", syscall.MS_RELATIME, nil),
+			m(20, 1, 8, 4, "/", "/", "ro,noatime,nodiratime,meow", o(), "ext3", "/dev/sda4", "rw,errors=continue,user_xattr,acl,barrier=0,data=ordered", syscall.MS_RDONLY|syscall.MS_NOATIME|syscall.MS_NODIRATIME, []string{"meow"}),
+		},
+			mn(20, 1, 8, 4, "/", "/", "ro,noatime,nodiratime,meow", o(), "ext3", "/dev/sda4", "rw,errors=continue,user_xattr,acl,barrier=0,data=ordered", false,
+				mn(15, 20, 0, 3, "/", "/proc", "rw,relatime", o(), "proc", "/proc", "rw", false, nil,
+					mn(16, 20, 0, 15, "/", "/sys", "rw,relatime", o(), "sysfs", "/sys", "rw", false, nil,
+						mn(17, 20, 0, 5, "/", "/dev", "rw,relatime", o(), "devtmpfs", "udev", "rw,size=1983516k,nr_inodes=495879,mode=755", false,
+							mn(18, 17, 0, 10, "/", "/dev/pts", "rw,relatime", o(), "devpts", "devpts", "rw,gid=5,mode=620,ptmxmode=000", false, nil,
+								mn(19, 17, 0, 16, "/", "/dev/shm", "rw,relatime", o(), "tmpfs", "tmpfs", "rw", false, nil, nil)),
+							nil))), nil), func(n *vfs.MountInfoNode) []*vfs.MountInfoNode {
+				return []*vfs.MountInfoNode{
+					n,
+					n.FirstChild,
+					n.FirstChild.NextSibling,
+					n.FirstChild.NextSibling.NextSibling,
+					n.FirstChild.NextSibling.NextSibling.FirstChild,
+					n.FirstChild.NextSibling.NextSibling.FirstChild.NextSibling,
+				}
+			}},
+
+		{"sample", sampleMountinfo, nil, "", []*wantMountInfo{
+			m(15, 20, 0, 3, "/", "/proc", "rw,relatime", o(), "proc", "/proc", "rw", syscall.MS_RELATIME, nil),
+			m(16, 20, 0, 15, "/", "/sys", "rw,relatime", o(), "sysfs", "/sys", "rw", syscall.MS_RELATIME, nil),
+			m(17, 20, 0, 5, "/", "/dev", "rw,relatime", o(), "devtmpfs", "udev", "rw,size=1983516k,nr_inodes=495879,mode=755", syscall.MS_RELATIME, nil),
+			m(18, 17, 0, 10, "/", "/dev/pts", "rw,relatime", o(), "devpts", "devpts", "rw,gid=5,mode=620,ptmxmode=000", syscall.MS_RELATIME, nil),
+			m(19, 17, 0, 16, "/", "/dev/shm", "rw,relatime", o(), "tmpfs", "tmpfs", "rw", syscall.MS_RELATIME, nil),
+			m(20, 1, 8, 4, "/", "/", "rw,noatime", o(), "ext3", "/dev/sda4", "rw,errors=continue,user_xattr,acl,barrier=0,data=ordered", syscall.MS_NOATIME, nil),
+			m(21, 16, 0, 17, "/", "/sys/fs/cgroup", "rw,nosuid,nodev,noexec,relatime", o(), "tmpfs", "tmpfs", "rw,mode=755", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(22, 21, 0, 18, "/", "/sys/fs/cgroup/systemd", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(23, 21, 0, 19, "/", "/sys/fs/cgroup/cpuset", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,cpuset", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(24, 21, 0, 20, "/", "/sys/fs/cgroup/ns", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,ns", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(25, 21, 0, 21, "/", "/sys/fs/cgroup/cpu", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,cpu", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(26, 21, 0, 22, "/", "/sys/fs/cgroup/cpuacct", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,cpuacct", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(27, 21, 0, 23, "/", "/sys/fs/cgroup/memory", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,memory", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(28, 21, 0, 24, "/", "/sys/fs/cgroup/devices", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,devices", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(29, 21, 0, 25, "/", "/sys/fs/cgroup/freezer", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,freezer", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(30, 21, 0, 26, "/", "/sys/fs/cgroup/net_cls", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,net_cls", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(31, 21, 0, 27, "/", "/sys/fs/cgroup/blkio", "rw,nosuid,nodev,noexec,relatime", o(), "cgroup", "cgroup", "rw,blkio", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC|syscall.MS_RELATIME, nil),
+			m(32, 16, 0, 28, "/", "/sys/kernel/security", "rw,relatime", o(), "autofs", "systemd-1", "rw,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct", syscall.MS_RELATIME, nil),
+			m(33, 17, 0, 29, "/", "/dev/hugepages", "rw,relatime", o(), "autofs", "systemd-1", "rw,fd=23,pgrp=1,timeout=300,minproto=5,maxproto=5,direct", syscall.MS_RELATIME, nil),
+			m(34, 16, 0, 30, "/", "/sys/kernel/debug", "rw,relatime", o(), "autofs", "systemd-1", "rw,fd=24,pgrp=1,timeout=300,minproto=5,maxproto=5,direct", syscall.MS_RELATIME, nil),
+			m(35, 15, 0, 31, "/", "/proc/sys/fs/binfmt_misc", "rw,relatime", o(), "autofs", "systemd-1", "rw,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct", syscall.MS_RELATIME, nil),
+			m(36, 17, 0, 32, "/", "/dev/mqueue", "rw,relatime", o(), "autofs", "systemd-1", "rw,fd=26,pgrp=1,timeout=300,minproto=5,maxproto=5,direct", syscall.MS_RELATIME, nil),
+			m(37, 15, 0, 14, "/", "/proc/bus/usb", "rw,relatime", o(), "usbfs", "/proc/bus/usb", "rw", syscall.MS_RELATIME, nil),
+			m(38, 33, 0, 33, "/", "/dev/hugepages", "rw,relatime", o(), "hugetlbfs", "hugetlbfs", "rw", syscall.MS_RELATIME, nil),
+			m(39, 36, 0, 12, "/", "/dev/mqueue", "rw,relatime", o(), "mqueue", "mqueue", "rw", syscall.MS_RELATIME, nil),
+			m(40, 20, 8, 6, "/", "/boot", "rw,noatime", o(), "ext3", "/dev/sda6", "rw,errors=continue,barrier=0,data=ordered", syscall.MS_NOATIME, nil),
+			m(41, 20, 253, 0, "/", "/home/kzak", "rw,noatime", o(), "ext4", "/dev/mapper/kzak-home", "rw,barrier=1,data=ordered", syscall.MS_NOATIME, nil),
+			m(42, 35, 0, 34, "/", "/proc/sys/fs/binfmt_misc", "rw,relatime", o(), "binfmt_misc", "none", "rw", syscall.MS_RELATIME, nil),
+			m(43, 16, 0, 35, "/", "/sys/fs/fuse/connections", "rw,relatime", o(), "fusectl", "fusectl", "rw", syscall.MS_RELATIME, nil),
+			m(44, 41, 0, 36, "/", "/home/kzak/.gvfs", "rw,nosuid,nodev,relatime", o(), "fuse.gvfs-fuse-daemon", "gvfs-fuse-daemon", "rw,user_id=500,group_id=500", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_RELATIME, nil),
+			m(45, 20, 0, 37, "/", "/var/lib/nfs/rpc_pipefs", "rw,relatime", o(), "rpc_pipefs", "sunrpc", "rw", syscall.MS_RELATIME, nil),
+			m(47, 20, 0, 38, "/", "/mnt/sounds", "rw,relatime", o(), "cifs", "//foo.home/bar/", "rw,unc=\\\\foo.home\\bar,username=kzak,domain=SRGROUP,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.111.1,posixpaths,serverino,acl,rsize=16384,wsize=57344", syscall.MS_RELATIME, nil),
+			m(49, 20, 0, 56, "/", "/mnt/test/foobar", "rw,relatime,nosymfollow", o("shared:323"), "tmpfs", "tmpfs", "rw", syscall.MS_RELATIME|vfs.MS_NOSYMFOLLOW, nil),
+		}, nil, nil},
+
+		{"sample nosrc", sampleMountinfoNoSrc, nil, "", []*wantMountInfo{
+			m(15, 20, 0, 3, "/", "/proc", "rw,relatime", o(), "proc", "/proc", "rw", syscall.MS_RELATIME, nil),
+			m(16, 20, 0, 15, "/", "/sys", "rw,relatime", o(), "sysfs", "/sys", "rw", syscall.MS_RELATIME, nil),
+			m(17, 20, 0, 5, "/", "/dev", "rw,relatime", o(), "devtmpfs", "udev", "rw,size=1983516k,nr_inodes=495879,mode=755", syscall.MS_RELATIME, nil),
+			m(18, 17, 0, 10, "/", "/dev/pts", "rw,relatime", o(), "devpts", "devpts", "rw,gid=5,mode=620,ptmxmode=000", syscall.MS_RELATIME, nil),
+			m(19, 17, 0, 16, "/", "/dev/shm", "rw,relatime", o(), "tmpfs", "tmpfs", "rw", syscall.MS_RELATIME, nil),
+			m(20, 1, 8, 4, "/", "/", "rw,noatime", o(), "ext3", "/dev/sda4", "rw,errors=continue,user_xattr,acl,barrier=0,data=ordered", syscall.MS_NOATIME, nil),
+			m(21, 20, 0, 53, "/", "/mnt/test", "rw,relatime", o("shared:212"), "tmpfs", "", "rw", syscall.MS_RELATIME, nil),
+		}, nil, nil},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Run("decode", func(t *testing.T) {
+				var got *vfs.MountInfo
+				d := vfs.NewMountInfoDecoder(strings.NewReader(tc.sample))
+				err := d.Decode(&got)
+				tc.check(t, d, "Decode",
+					func(yield func(*vfs.MountInfoEntry) bool) {
+						for cur := got; cur != nil; cur = cur.Next {
+							if !yield(&cur.MountInfoEntry) {
+								return
+							}
+						}
+					}, func() error { return err })
+				t.Run("reuse", func(t *testing.T) {
+					tc.check(t, d, "Entries",
+						d.Entries(), d.Err)
+				})
+			})
+
+			t.Run("iter", func(t *testing.T) {
+				d := vfs.NewMountInfoDecoder(strings.NewReader(tc.sample))
+				tc.check(t, d, "Entries",
+					d.Entries(), d.Err)
+
+				t.Run("reuse", func(t *testing.T) {
+					tc.check(t, d, "Entries",
+						d.Entries(), d.Err)
+				})
+			})
+
+			t.Run("yield", func(t *testing.T) {
+				d := vfs.NewMountInfoDecoder(strings.NewReader(tc.sample))
+				v := false
+				d.Entries()(func(entry *vfs.MountInfoEntry) bool { v = !v; return v })
+				d.Entries()(func(entry *vfs.MountInfoEntry) bool { return false })
+
+				tc.check(t, d, "Entries",
+					d.Entries(), d.Err)
+
+				t.Run("reuse", func(t *testing.T) {
+					tc.check(t, d, "Entries",
+						d.Entries(), d.Err)
+				})
+			})
+		})
+	}
+}
+
+type mountInfoTest struct {
+	name      string
+	sample    string
+	wantErr   error
+	wantError string
+	want      []*wantMountInfo
+
+	wantNode     *vfs.MountInfoNode
+	wantCollectF func(n *vfs.MountInfoNode) []*vfs.MountInfoNode
+}
+
+func (tc *mountInfoTest) check(t *testing.T, d *vfs.MountInfoDecoder, funcName string,
+	got iter.Seq[*vfs.MountInfoEntry], gotErr func() error) {
+	i := 0
+	for cur := range got {
+		if i == len(tc.want) {
+			if funcName != "Decode" && (tc.wantErr != nil || tc.wantError != "") {
+				continue
+			}
+
+			t.Errorf("%s: got more than %d entries", funcName, len(tc.want))
+			break
+		}
+
+		if !reflect.DeepEqual(cur, &tc.want[i].MountInfoEntry) {
+			t.Errorf("%s: entry %d\ngot:  %#v\nwant: %#v",
+				funcName, i, cur, tc.want[i])
+		}
+
+		flags, unmatched := cur.Flags()
+		if flags != tc.want[i].flags {
+			t.Errorf("Flags(%q): %#x, want %#x",
+				cur.VfsOptstr, flags, tc.want[i].flags)
+		}
+		if !slices.Equal(unmatched, tc.want[i].unmatched) {
+			t.Errorf("Flags(%q): unmatched = %#q, want %#q",
+				cur.VfsOptstr, unmatched, tc.want[i].unmatched)
+		}
+
+		i++
+	}
+
+	if i != len(tc.want) {
+		t.Errorf("%s: got %d entries, want %d", funcName, i, len(tc.want))
+	}
+
+	if tc.wantErr == nil && tc.wantError == "" && tc.wantCollectF != nil {
+		t.Run("unfold", func(t *testing.T) {
+			n, err := d.Unfold("/")
+			if err != nil {
+				t.Errorf("Unfold: error = %v", err)
+			} else {
+				t.Run("stop", func(t *testing.T) {
+					v := false
+					n.Collective()(func(node *vfs.MountInfoNode) bool { v = !v; return v })
+				})
+
+				if !reflect.DeepEqual(n, tc.wantNode) {
+					t.Errorf("Unfold: %s, want %s",
+						mustMarshal(n), mustMarshal(tc.wantNode))
+				}
+
+				t.Run("collective", func(t *testing.T) {
+					wantCollect := tc.wantCollectF(n)
+					if gotCollect := slices.Collect(n.Collective()); !reflect.DeepEqual(gotCollect, wantCollect) {
+						t.Errorf("Collective: \ngot  %#v\nwant %#v",
+							gotCollect, wantCollect)
+					}
+				})
+			}
+		})
+	} else if tc.wantNode != nil || tc.wantCollectF != nil {
+		panic("invalid test case")
+	} else if _, err := d.Unfold("/"); !errors.Is(err, tc.wantErr) {
+		if tc.wantError == "" {
+			t.Errorf("Unfold: error = %v, wantErr %v",
+				err, tc.wantErr)
+		} else if err != nil && err.Error() != tc.wantError {
+			t.Errorf("Unfold: error = %q, wantError %q",
+				err, tc.wantError)
+		}
+	}
+
+	if err := gotErr(); !errors.Is(err, tc.wantErr) {
+		if tc.wantError == "" {
+			t.Errorf("%s: error = %v, wantErr %v",
+				funcName, err, tc.wantErr)
+		} else if err != nil && err.Error() != tc.wantError {
+			t.Errorf("%s: error = %q, wantError %q",
+				funcName, err, tc.wantError)
+		}
+	}
+}
+
+func mustMarshal(v any) string {
+	p, err := json.Marshal(v)
+	if err != nil {
+		panic(err.Error())
+	}
+	return string(p)
+}
+
+type wantMountInfo struct {
+	vfs.MountInfoEntry
+	flags     uintptr
+	unmatched []string
+}
+
+func m(
+	id, parent, maj, min int, root, target, vfsOptstr string, optFields []string, fsType, source, fsOptstr string,
+	flags uintptr, unmatched []string,
+) *wantMountInfo {
+	return &wantMountInfo{
+		vfs.MountInfoEntry{
+			ID:        id,
+			Parent:    parent,
+			Devno:     vfs.DevT{maj, min},
+			Root:      root,
+			Target:    target,
+			VfsOptstr: vfsOptstr,
+			OptFields: optFields,
+			FsType:    fsType,
+			Source:    source,
+			FsOptstr:  fsOptstr,
+		}, flags, unmatched,
+	}
+}
+
+func mn(
+	id, parent, maj, min int, root, target, vfsOptstr string, optFields []string, fsType, source, fsOptstr string,
+	covered bool, firstChild, nextSibling *vfs.MountInfoNode,
+) *vfs.MountInfoNode {
+	return &vfs.MountInfoNode{
+		MountInfoEntry: &vfs.MountInfoEntry{
+			ID:        id,
+			Parent:    parent,
+			Devno:     vfs.DevT{maj, min},
+			Root:      root,
+			Target:    target,
+			VfsOptstr: vfsOptstr,
+			OptFields: optFields,
+			FsType:    fsType,
+			Source:    source,
+			FsOptstr:  fsOptstr,
+		},
+		FirstChild:  firstChild,
+		NextSibling: nextSibling,
+		Clean:       path.Clean(target),
+		Covered:     covered,
+	}
+}
+
+func o(field ...string) []string {
+	if field == nil {
+		return []string{}
+	}
+	return field
+}
+
+const (
+	sampleMountinfoBase = `15 20 0:3 / /proc rw,relatime - proc /proc rw
+16 20 0:15 / /sys rw,relatime - sysfs /sys rw
+17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=1983516k,nr_inodes=495879,mode=755
+18 17 0:10 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000
+19 17 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw
+20 1 8:4 / / ro,noatime,nodiratime,meow - ext3 /dev/sda4 rw,errors=continue,user_xattr,acl,barrier=0,data=ordered`
+
+	sampleMountinfo = `15 20 0:3 / /proc rw,relatime - proc /proc rw
+16 20 0:15 / /sys rw,relatime - sysfs /sys rw
+17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=1983516k,nr_inodes=495879,mode=755
+18 17 0:10 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000
+19 17 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw
+20 1 8:4 / / rw,noatime - ext3 /dev/sda4 rw,errors=continue,user_xattr,acl,barrier=0,data=ordered
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755
+22 21 0:18 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd
+23 21 0:19 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpuset
+24 21 0:20 / /sys/fs/cgroup/ns rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,ns
+25 21 0:21 / /sys/fs/cgroup/cpu rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpu
+26 21 0:22 / /sys/fs/cgroup/cpuacct rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpuacct
+27 21 0:23 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,memory
+28 21 0:24 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,devices
+29 21 0:25 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,freezer
+30 21 0:26 / /sys/fs/cgroup/net_cls rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,net_cls
+31 21 0:27 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,blkio
+32 16 0:28 / /sys/kernel/security rw,relatime - autofs systemd-1 rw,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+33 17 0:29 / /dev/hugepages rw,relatime - autofs systemd-1 rw,fd=23,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+34 16 0:30 / /sys/kernel/debug rw,relatime - autofs systemd-1 rw,fd=24,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+35 15 0:31 / /proc/sys/fs/binfmt_misc rw,relatime - autofs systemd-1 rw,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+36 17 0:32 / /dev/mqueue rw,relatime - autofs systemd-1 rw,fd=26,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+37 15 0:14 / /proc/bus/usb rw,relatime - usbfs /proc/bus/usb rw
+38 33 0:33 / /dev/hugepages rw,relatime - hugetlbfs hugetlbfs rw
+39 36 0:12 / /dev/mqueue rw,relatime - mqueue mqueue rw
+40 20 8:6 / /boot rw,noatime - ext3 /dev/sda6 rw,errors=continue,barrier=0,data=ordered
+41 20 253:0 / /home/kzak rw,noatime - ext4 /dev/mapper/kzak-home rw,barrier=1,data=ordered
+42 35 0:34 / /proc/sys/fs/binfmt_misc rw,relatime - binfmt_misc none rw
+43 16 0:35 / /sys/fs/fuse/connections rw,relatime - fusectl fusectl rw
+44 41 0:36 / /home/kzak/.gvfs rw,nosuid,nodev,relatime - fuse.gvfs-fuse-daemon gvfs-fuse-daemon rw,user_id=500,group_id=500
+45 20 0:37 / /var/lib/nfs/rpc_pipefs rw,relatime - rpc_pipefs sunrpc rw
+47 20 0:38 / /mnt/sounds rw,relatime - cifs //foo.home/bar/ rw,unc=\\foo.home\bar,username=kzak,domain=SRGROUP,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.111.1,posixpaths,serverino,acl,rsize=16384,wsize=57344
+49 20 0:56 / /mnt/test/foobar rw,relatime,nosymfollow shared:323 - tmpfs tmpfs rw`
+
+	sampleMountinfoNoSrc = `15 20 0:3 / /proc rw,relatime - proc /proc rw
+16 20 0:15 / /sys rw,relatime - sysfs /sys rw
+17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=1983516k,nr_inodes=495879,mode=755
+18 17 0:10 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000
+19 17 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw
+20 1 8:4 / / rw,noatime - ext3 /dev/sda4 rw,errors=continue,user_xattr,acl,barrier=0,data=ordered
+21 20 0:53 / /mnt/test rw,relatime shared:212 - tmpfs  rw`
+)

sandbox/vfs/unfold.go

@@ -0,0 +1,107 @@
+package vfs
+
+import (
+	"iter"
+	"path"
+	"strings"
+	"syscall"
+)
+
+// MountInfoNode positions a [MountInfoEntry] in its mount hierarchy.
+type MountInfoNode struct {
+	*MountInfoEntry
+	FirstChild  *MountInfoNode `json:"first_child"`
+	NextSibling *MountInfoNode `json:"next_sibling"`
+
+	Clean   string `json:"clean"`
+	Covered bool   `json:"covered"`
+}
+
+// Collective returns an iterator over visible mountinfo nodes.
+func (n *MountInfoNode) Collective() iter.Seq[*MountInfoNode] {
+	return func(yield func(*MountInfoNode) bool) { n.visit(yield) }
+}
+
+func (n *MountInfoNode) visit(yield func(*MountInfoNode) bool) bool {
+	if !n.Covered && !yield(n) {
+		return false
+	}
+	for cur := n.FirstChild; cur != nil; cur = cur.NextSibling {
+		if !cur.visit(yield) {
+			return false
+		}
+	}
+	return true
+}
+
+// Unfold unfolds the mount hierarchy and resolves covered paths.
+func (d *MountInfoDecoder) Unfold(target string) (*MountInfoNode, error) {
+	targetClean := path.Clean(target)
+
+	var mountinfoSize int
+	for range d.Entries() {
+		mountinfoSize++
+	}
+	if err := d.Err(); err != nil {
+		return nil, err
+	}
+
+	mountinfo := make([]*MountInfoNode, mountinfoSize)
+	// mount ID to index lookup
+	idIndex := make(map[int]int, mountinfoSize)
+	// final entry to match target
+	targetIndex := -1
+	{
+		i := 0
+		for ent := range d.Entries() {
+			mountinfo[i] = &MountInfoNode{Clean: path.Clean(ent.Target), MountInfoEntry: ent}
+			idIndex[ent.ID] = i
+			if mountinfo[i].Clean == targetClean {
+				targetIndex = i
+			}
+
+			i++
+		}
+	}
+
+	if targetIndex == -1 {
+		return nil, syscall.ESTALE
+	}
+
+	for _, cur := range mountinfo {
+		var parent *MountInfoNode
+		if p, ok := idIndex[cur.Parent]; !ok {
+			continue
+		} else {
+			parent = mountinfo[p]
+		}
+
+		if !strings.HasPrefix(cur.Clean, targetClean) {
+			continue
+		}
+		if parent.Clean == cur.Clean {
+			parent.Covered = true
+		}
+
+		covered := false
+		nsp := &parent.FirstChild
+		for s := parent.FirstChild; s != nil; s = s.NextSibling {
+			if strings.HasPrefix(cur.Clean, s.Clean) {
+				covered = true
+				break
+			}
+
+			if strings.HasPrefix(s.Clean, cur.Clean) {
+				*nsp = s.NextSibling
+			} else {
+				nsp = &s.NextSibling
+			}
+		}
+		if covered {
+			continue
+		}
+		*nsp = cur
+	}
+
+	return mountinfo[targetIndex], nil
+}

sandbox/vfs/unfold_test.go

@@ -0,0 +1,93 @@
+package vfs_test
+
+import (
+	"errors"
+	"reflect"
+	"slices"
+	"strings"
+	"syscall"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/sandbox/vfs"
+)
+
+func TestUnfold(t *testing.T) {
+	testCases := []struct {
+		name    string
+		sample  string
+		target  string
+		wantErr error
+
+		want         *vfs.MountInfoNode
+		wantCollectF func(n *vfs.MountInfoNode) []*vfs.MountInfoNode
+		wantCollectN []string
+	}{
+		{
+			"no match",
+			sampleMountinfoBase,
+			"/mnt",
+			syscall.ESTALE, nil, nil, nil,
+		},
+		{
+			"cover",
+			`33 1 0:33 / / rw,relatime shared:1 - tmpfs impure rw,size=16777216k,mode=755
+37 33 0:32 / /proc rw,nosuid,nodev,noexec,relatime shared:41 - proc proc rw
+551 33 0:121 / /mnt rw,relatime shared:666 - tmpfs tmpfs rw
+595 551 0:123 / /mnt rw,relatime shared:990 - tmpfs tmpfs rw
+611 595 0:142 / /mnt/etc rw,relatime shared:1112 - tmpfs tmpfs rw
+625 644 0:142 /passwd /mnt/etc/passwd rw,relatime shared:1112 - tmpfs tmpfs rw
+641 625 0:33 /etc/passwd /mnt/etc/passwd rw,relatime shared:1 - tmpfs impure rw,size=16777216k,mode=755
+644 611 0:33 /etc/passwd /mnt/etc/passwd rw,relatime shared:1 - tmpfs impure rw,size=16777216k,mode=755
+`, "/mnt", nil,
+			mn(595, 551, 0, 123, "/", "/mnt", "rw,relatime", o("shared:990"), "tmpfs", "tmpfs", "rw", false,
+				mn(611, 595, 0, 142, "/", "/mnt/etc", "rw,relatime", o("shared:1112"), "tmpfs", "tmpfs", "rw", false,
+					mn(644, 611, 0, 33, "/etc/passwd", "/mnt/etc/passwd", "rw,relatime", o("shared:1"), "tmpfs", "impure", "rw,size=16777216k,mode=755", true,
+						mn(625, 644, 0, 142, "/passwd", "/mnt/etc/passwd", "rw,relatime", o("shared:1112"), "tmpfs", "tmpfs", "rw", true,
+							mn(641, 625, 0, 33, "/etc/passwd", "/mnt/etc/passwd", "rw,relatime", o("shared:1"), "tmpfs", "impure", "rw,size=16777216k,mode=755", false,
+								nil, nil), nil), nil), nil), nil), func(n *vfs.MountInfoNode) []*vfs.MountInfoNode {
+				return []*vfs.MountInfoNode{n, n.FirstChild, n.FirstChild.FirstChild.FirstChild.FirstChild}
+			}, []string{"/mnt", "/mnt/etc", "/mnt/etc/passwd"},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			d := vfs.NewMountInfoDecoder(strings.NewReader(tc.sample))
+			got, err := d.Unfold(tc.target)
+
+			if !errors.Is(err, tc.wantErr) {
+				t.Errorf("Unfold: error = %v, wantErr %v",
+					err, tc.wantErr)
+			}
+
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("Unfold:\ngot  %s\nwant %s",
+					mustMarshal(got), mustMarshal(tc.want))
+			}
+
+			if err == nil && tc.wantCollectF != nil {
+				t.Run("collective", func(t *testing.T) {
+					wantCollect := tc.wantCollectF(got)
+					gotCollect := slices.Collect(got.Collective())
+					if !reflect.DeepEqual(gotCollect, wantCollect) {
+						t.Errorf("Collective: \ngot  %#v\nwant %#v",
+							gotCollect, wantCollect)
+					}
+					t.Run("target", func(t *testing.T) {
+						gotCollectN := slices.Collect[string](func(yield func(v string) bool) {
+							for _, cur := range gotCollect {
+								if !yield(cur.Clean) {
+									return
+								}
+							}
+						})
+						if !reflect.DeepEqual(gotCollectN, tc.wantCollectN) {
+							t.Errorf("Collective: got %q, want %q",
+								gotCollectN, tc.wantCollectN)
+						}
+					})
+				})
+			}
+		})
+	}
+}