release: 0.3.3

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

.gitea/workflows/test.yml

@@ -22,6 +22,57 @@ jobs:
           path: result/*
           retention-days: 1
 
+  race:
+    name: Fortify (race detector)
+    runs-on: nix
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run NixOS test
+        run: nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.race
+
+      - name: Upload test output
+        uses: actions/upload-artifact@v3
+        with:
+          name: "fortify-race-vm-output"
+          path: result/*
+          retention-days: 1
+
+  sandbox:
+    name: Sandbox
+    runs-on: nix
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run NixOS test
+        run: nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.sandbox
+
+      - name: Upload test output
+        uses: actions/upload-artifact@v3
+        with:
+          name: "sandbox-vm-output"
+          path: result/*
+          retention-days: 1
+
+  sandbox-race:
+    name: Sandbox (race detector)
+    runs-on: nix
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run NixOS test
+        run: nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.sandbox-race
+
+      - name: Upload test output
+        uses: actions/upload-artifact@v3
+        with:
+          name: "sandbox-race-vm-output"
+          path: result/*
+          retention-days: 1
+
   fpkg:
     name: Fpkg
     runs-on: nix
@@ -39,29 +90,14 @@ jobs:
           path: result/*
           retention-days: 1
 
-  race:
-    name: Data race detector
-    runs-on: nix
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Run NixOS test
-        run: nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.race
-
-      - name: Upload test output
-        uses: actions/upload-artifact@v3
-        with:
-          name: "fortify-race-vm-output"
-          path: result/*
-          retention-days: 1
-
   check:
     name: Flake checks
     needs:
       - fortify
-      - fpkg
       - race
+      - sandbox
+      - sandbox-race
+      - fpkg
     runs-on: nix
     steps:
       - name: Checkout

cmd/fpkg/app.go

@@ -73,6 +73,7 @@ func (app *appInfo) toFst(pathSet *appPathSet, argv []string, flagDropShell bool
 			Username: "fortify",
 			Inner:    path.Join("/data/data", app.ID),
 			Outer:    pathSet.homeDir,
+			Shell:    shellPath,
 			Sandbox: &fst.SandboxConfig{
 				Hostname:      formatHostname(app.Name),
 				Devel:         app.Devel,

cmd/fpkg/with.go

@@ -34,6 +34,7 @@ func withNixDaemon(
 			Username: "fortify",
 			Inner:    path.Join("/data/data", app.ID),
 			Outer:    pathSet.homeDir,
+			Shell:    shellPath,
 			Sandbox: &fst.SandboxConfig{
 				Hostname: formatHostname(app.Name) + "-" + action,
 				Userns:   true, // nix sandbox requires userns
@@ -72,6 +73,7 @@ func withCacheDir(
 			Username: "nixos",
 			Inner:    path.Join("/data/data", app.ID, "cache"),
 			Outer:    pathSet.cacheDir, // this also ensures cacheDir via shim
+			Shell:    shellPath,
 			Sandbox: &fst.SandboxConfig{
 				Hostname: formatHostname(app.Name) + "-" + action,
 				Seccomp:  seccomp.FlagMultiarch,

dbus/dbus_test.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"syscall"
 	"testing"
 	"time"
 
@@ -71,7 +72,7 @@ func TestProxy_Seal(t *testing.T) {
 	for id, tc := range testCasePairs() {
 		t.Run("create seal for "+id, func(t *testing.T) {
 			p := dbus.New(tc[0].bus, tc[1].bus)
-			if err := p.Seal(tc[0].c, tc[1].c); (errors.Is(err, helper.ErrContainsNull)) != tc[0].wantErr {
+			if err := p.Seal(tc[0].c, tc[1].c); (errors.Is(err, syscall.EINVAL)) != tc[0].wantErr {
 				t.Errorf("Seal(%p, %p) error = %v, wantErr %v",
 					tc[0].c, tc[1].c,
 					err, tc[0].wantErr)

flake.lock

@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1742234739,
-        "narHash": "sha256-zFL6zsf/5OztR1NSNQF33dvS1fL/BzVUjabZq4qrtY4=",
+        "lastModified": 1742655702,
+        "narHash": "sha256-jbqlw4sPArFtNtA1s3kLg7/A4fzP4GLk9bGbtUJg0JQ=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "f6af7280a3390e65c2ad8fd059cdc303426cbd59",
+        "rev": "0948aeedc296f964140d9429223c7e4a0702a1ff",
         "type": "github"
       },
       "original": {
@@ -23,11 +23,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1742512142,
-        "narHash": "sha256-8XfURTDxOm6+33swQJu/hx6xw1Tznl8vJJN5HwVqckg=",
+        "lastModified": 1743231893,
+        "narHash": "sha256-tpJsHMUPEhEnzySoQxx7+kA+KUtgWqvlcUBqROYNNt0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "7105ae3957700a9646cc4b766f5815b23ed0c682",
+        "rev": "c570c1f5304493cafe133b8d843c7c1c4a10d3a6",
         "type": "github"
       },
       "original": {

flake.nix

@@ -58,12 +58,19 @@
         in
         {
           fortify = callPackage ./test { inherit system self; };
-          fpkg = callPackage ./cmd/fpkg/test { inherit system self; };
           race = callPackage ./test {
             inherit system self;
             withRace = true;
           };
 
+          sandbox = callPackage ./test/sandbox { inherit self; };
+          sandbox-race = callPackage ./test/sandbox {
+            inherit self;
+            withRace = true;
+          };
+
+          fpkg = callPackage ./cmd/fpkg/test { inherit system self; };
+
           formatting = runCommandLocal "check-formatting" { nativeBuildInputs = [ nixfmt-rfc-style ]; } ''
             cd ${./.}
 

fst/config.go

@@ -35,6 +35,8 @@ type ConfinementConfig struct {
 	Inner string `json:"home_inner"`
 	// home directory in init namespace
 	Outer string `json:"home"`
+	// absolute path to shell, empty for host shell
+	Shell string `json:"shell,omitempty"`
 	// abstract sandbox configuration
 	Sandbox *SandboxConfig `json:"sandbox"`
 	// extra acl ops, runs after everything else
@@ -97,6 +99,7 @@ func Template() *Config {
 			Username: "chronos",
 			Outer:    "/var/lib/persist/home/org.chromium.Chromium",
 			Inner:    "/var/lib/fortify",
+			Shell:    "/run/current-system/sw/bin/zsh",
 			Sandbox: &SandboxConfig{
 				Hostname:      "localhost",
 				Devel:         true,

fst/sandbox.go

@@ -97,6 +97,10 @@ func (s *SandboxConfig) ToContainer(sys SandboxSys, uid, gid *int) (*sandbox.Par
 		Seccomp:  s.Seccomp,
 	}
 
+	if s.Multiarch {
+		container.Seccomp |= seccomp.FlagMultiarch
+	}
+
 	/* 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 */

helper/args.go

@@ -1,38 +1,17 @@
 package helper
 
 import (
-	"errors"
+	"bytes"
 	"io"
-	"strings"
+	"syscall"
 )
 
-var (
-	ErrContainsNull = errors.New("argument contains null character")
-)
-
-type argsWt []string
-
-// checks whether any element contains the null character
-// must be called before args use and args must not be modified after call
-func (a argsWt) check() error {
-	for _, arg := range a {
-		for _, b := range arg {
-			if b == '\x00' {
-				return ErrContainsNull
-			}
-		}
-	}
-
-	return nil
-}
+type argsWt [][]byte
 
 func (a argsWt) WriteTo(w io.Writer) (int64, error) {
-	// assuming already checked
-
 	nt := 0
-	// write null terminated arguments
 	for _, arg := range a {
-		n, err := w.Write([]byte(arg + "\x00"))
+		n, err := w.Write(arg)
 		nt += n
 
 		if err != nil {
@@ -44,18 +23,32 @@ func (a argsWt) WriteTo(w io.Writer) (int64, error) {
 }
 
 func (a argsWt) String() string {
-	return strings.Join(a, " ")
+	return string(
+		bytes.TrimSuffix(
+			bytes.ReplaceAll(
+				bytes.Join(a, nil),
+				[]byte{0}, []byte{' '},
+			),
+			[]byte{' '},
+		),
+	)
 }
 
-// NewCheckedArgs returns a checked argument writer for args.
-// Callers must not retain any references to args.
-func NewCheckedArgs(args []string) (io.WriterTo, error) {
-	a := argsWt(args)
-	return a, a.check()
+// NewCheckedArgs returns a checked null-terminated argument writer for a copy of args.
+func NewCheckedArgs(args []string) (wt io.WriterTo, err error) {
+	a := make(argsWt, len(args))
+	for i, arg := range args {
+		a[i], err = syscall.ByteSliceFromString(arg)
+		if err != nil {
+			return
+		}
+	}
+	wt = a
+	return
 }
 
-// MustNewCheckedArgs returns a checked argument writer for args and panics if check fails.
-// Callers must not retain any references to args.
+// MustNewCheckedArgs returns a checked null-terminated argument writer for a copy of args.
+// If s contains a NUL byte this function panics instead of returning an error.
 func MustNewCheckedArgs(args []string) io.WriterTo {
 	a, err := NewCheckedArgs(args)
 	if err != nil {

helper/args_test.go

@@ -4,34 +4,33 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"syscall"
 	"testing"
 
 	"git.gensokyo.uk/security/fortify/helper"
 )
 
-func Test_argsFd_String(t *testing.T) {
+func TestArgsString(t *testing.T) {
 	wantString := strings.Join(wantArgs, " ")
 	if got := argsWt.(fmt.Stringer).String(); got != wantString {
-		t.Errorf("String(): got %v; want %v",
+		t.Errorf("String: %q, want %q",
 			got, wantString)
 	}
 }
 
 func TestNewCheckedArgs(t *testing.T) {
 	args := []string{"\x00"}
-	if _, err := helper.NewCheckedArgs(args); !errors.Is(err, helper.ErrContainsNull) {
-		t.Errorf("NewCheckedArgs(%q) error = %v, wantErr %v",
-			args,
-			err, helper.ErrContainsNull)
+	if _, err := helper.NewCheckedArgs(args); !errors.Is(err, syscall.EINVAL) {
+		t.Errorf("NewCheckedArgs: error = %v, wantErr %v",
+			err, syscall.EINVAL)
 	}
 
 	t.Run("must panic", func(t *testing.T) {
 		badPayload := []string{"\x00"}
 		defer func() {
-			wantPanic := "argument contains null character"
+			wantPanic := "invalid argument"
 			if r := recover(); r != wantPanic {
-				t.Errorf("MustNewCheckedArgs(%q) panic = %v, wantPanic %v",
-					badPayload,
+				t.Errorf("MustNewCheckedArgs: panic = %v, wantPanic %v",
 					r, wantPanic)
 			}
 		}()

helper/helper_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"strconv"
 	"strings"
 	"testing"
@@ -55,8 +56,8 @@ func testHelper(t *testing.T, createHelper func(ctx context.Context, setOutput f
 
 	t.Run("start helper with status channel and wait", func(t *testing.T) {
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-		stdout, stderr := new(strings.Builder), new(strings.Builder)
-		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, stderr }, true)
+		stdout := new(strings.Builder)
+		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, os.Stderr }, true)
 
 		t.Run("wait not yet started helper", func(t *testing.T) {
 			defer func() {
@@ -88,8 +89,8 @@ func testHelper(t *testing.T, createHelper func(ctx context.Context, setOutput f
 
 		t.Log("waiting on helper")
 		if err := h.Wait(); !errors.Is(err, context.Canceled) {
-			t.Errorf("Wait() err = %v stderr = %s",
-				err, stderr)
+			t.Errorf("Wait: error = %v",
+				err)
 		}
 
 		t.Run("wait already finalised helper", func(t *testing.T) {
@@ -101,8 +102,8 @@ func testHelper(t *testing.T, createHelper func(ctx context.Context, setOutput f
 			}
 		})
 
-		if got := stderr.String(); got != wantPayload {
-			t.Errorf("Start: stderr = %v, want %v",
+		if got := trimStdout(stdout); got != wantPayload {
+			t.Errorf("Start: stdout = %q, want %q",
 				got, wantPayload)
 		}
 	})
@@ -110,23 +111,27 @@ func testHelper(t *testing.T, createHelper func(ctx context.Context, setOutput f
 	t.Run("start helper and wait", func(t *testing.T) {
 		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)
+		stdout := new(strings.Builder)
+		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, os.Stderr }, false)
 
 		if err := h.Start(); err != nil {
-			t.Errorf("Start() error = %v",
+			t.Errorf("Start: error = %v",
 				err)
 			return
 		}
 
 		if err := h.Wait(); err != nil {
-			t.Errorf("Wait() err = %v stdout = %s stderr = %s",
-				err, stdout, stderr)
+			t.Errorf("Wait: error = %v stdout = %q",
+				err, stdout)
 		}
 
-		if got := stderr.String(); got != wantPayload {
-			t.Errorf("Start() stderr = %v, want %v",
+		if got := trimStdout(stdout); got != wantPayload {
+			t.Errorf("Start: stdout = %q, want %q",
 				got, wantPayload)
 		}
 	})
 }
+
+func trimStdout(stdout fmt.Stringer) string {
+	return strings.TrimPrefix(stdout.String(), "=== RUN   TestHelperInit\n")
+}

helper/stub.go

@@ -63,7 +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.Stderr, argsFile); err != nil {
+		if _, err := io.Copy(os.Stdout, argsFile); err != nil {
 			panic("cannot read args: " + err.Error())
 		}
 	}

internal/app/app_nixos_test.go

@@ -56,15 +56,15 @@ var testCasesNixos = []sealTestCase{
 		},
 		system.New(1000001).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ensure("/run/user/1971/fortify", 0700).UpdatePermType(system.User, "/run/user/1971/fortify", acl.Execute).
-			Ensure("/run/user/1971", 0700).UpdatePermType(system.User, "/run/user/1971", acl.Execute). // this is ordered as is because the previous Ensure only calls mkdir if XDG_RUNTIME_DIR is unset
-			Ephemeral(system.Process, "/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1", 0711).
-			Ephemeral(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir", 0700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir/1", 01700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir/1", acl.Read, acl.Write, acl.Execute).
+			Ensure("/run/user/1971/fortify", 0700).UpdatePermType(system.User, "/run/user/1971/fortify", acl.Execute).
+			Ensure("/run/user/1971", 0700).UpdatePermType(system.User, "/run/user/1971", acl.Execute). // this is ordered as is because the previous Ensure only calls mkdir if XDG_RUNTIME_DIR is unset
 			UpdatePermType(system.EWayland, "/run/user/1971/wayland-0", acl.Read, acl.Write, acl.Execute).
+			Ephemeral(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", acl.Execute).
 			Link("/run/user/1971/pulse/native", "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1/pulse").
 			CopyFile(nil, "/home/ophestra/xdg/config/pulse/cookie", 256, 256).
+			Ephemeral(system.Process, "/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1", 0711).
 			MustProxyDBus("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/bus", &dbus.Config{
 				Talk: []string{
 					"org.freedesktop.FileManager1", "org.freedesktop.Notifications",
@@ -101,6 +101,7 @@ var testCasesNixos = []sealTestCase{
 				"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",

internal/app/app_pd_test.go

@@ -28,10 +28,6 @@ var testCasesPd = []sealTestCase{
 		},
 		system.New(1000000).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ensure("/run/user/1971/fortify", 0700).UpdatePermType(system.User, "/run/user/1971/fortify", acl.Execute).
-			Ensure("/run/user/1971", 0700).UpdatePermType(system.User, "/run/user/1971", acl.Execute). // this is ordered as is because the previous Ensure only calls mkdir if XDG_RUNTIME_DIR is unset
-			Ephemeral(system.Process, "/tmp/fortify.1971/4a450b6596d7bc15bd01780eb9a607ac", 0711).
-			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),
 		&sandbox.Params{
@@ -41,6 +37,7 @@ var testCasesPd = []sealTestCase{
 			Args:  []string{"/run/current-system/sw/bin/zsh"},
 			Env: []string{
 				"HOME=/home/chronos",
+				"SHELL=/run/current-system/sw/bin/zsh",
 				"TERM=xterm-256color",
 				"USER=chronos",
 				"XDG_RUNTIME_DIR=/run/user/65534",
@@ -206,14 +203,13 @@ var testCasesPd = []sealTestCase{
 		},
 		system.New(1000009).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ensure("/run/user/1971/fortify", 0700).UpdatePermType(system.User, "/run/user/1971/fortify", acl.Execute).
-			Ensure("/run/user/1971", 0700).UpdatePermType(system.User, "/run/user/1971", acl.Execute). // this is ordered as is because the previous Ensure only calls mkdir if XDG_RUNTIME_DIR is unset
-			Ephemeral(system.Process, "/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c", 0711).
-			Ephemeral(system.Process, "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir", 0700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir", acl.Execute).
 			Ensure("/tmp/fortify.1971/tmpdir/9", 01700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir/9", acl.Read, acl.Write, acl.Execute).
-			Ensure("/tmp/fortify.1971/wayland", 0711).
-			Wayland(new(*os.File), "/tmp/fortify.1971/wayland/ebf083d1b175911782d413369b64ce7c", "/run/user/1971/wayland-0", "org.chromium.Chromium", "ebf083d1b175911782d413369b64ce7c").
+			Ephemeral(system.Process, "/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c", 0711).
+			Wayland(new(*os.File), "/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/wayland", "/run/user/1971/wayland-0", "org.chromium.Chromium", "ebf083d1b175911782d413369b64ce7c").
+			Ensure("/run/user/1971/fortify", 0700).UpdatePermType(system.User, "/run/user/1971/fortify", acl.Execute).
+			Ensure("/run/user/1971", 0700).UpdatePermType(system.User, "/run/user/1971", acl.Execute). // this is ordered as is because the previous Ensure only calls mkdir if XDG_RUNTIME_DIR is unset
+			Ephemeral(system.Process, "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c", acl.Execute).
 			Link("/run/user/1971/pulse/native", "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c/pulse").
 			CopyFile(new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 256, 256).
 			MustProxyDBus("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/bus", &dbus.Config{
@@ -259,6 +255,7 @@ var testCasesPd = []sealTestCase{
 				"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",
@@ -371,7 +368,7 @@ var testCasesPd = []sealTestCase{
 				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("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/wayland", "/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).

internal/app/seal.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"maps"
 	"os"
 	"path"
 	"regexp"
@@ -86,6 +85,53 @@ type outcome struct {
 	f atomic.Bool
 }
 
+// shareHost holds optional share directory state that must not be accessed directly
+type shareHost struct {
+	// whether XDG_RUNTIME_DIR is used post fsu
+	useRuntimeDir bool
+	// process-specific directory in tmpdir, empty if unused
+	sharePath string
+	// process-specific directory in XDG_RUNTIME_DIR, empty if unused
+	runtimeSharePath string
+
+	seal *outcome
+	sc   fst.Paths
+}
+
+// ensureRuntimeDir must be called if direct access to paths within XDG_RUNTIME_DIR is required
+func (share *shareHost) ensureRuntimeDir() {
+	if share.useRuntimeDir {
+		return
+	}
+	share.useRuntimeDir = true
+	share.seal.sys.Ensure(share.sc.RunDirPath, 0700)
+	share.seal.sys.UpdatePermType(system.User, share.sc.RunDirPath, acl.Execute)
+	share.seal.sys.Ensure(share.sc.RuntimePath, 0700) // ensure this dir in case XDG_RUNTIME_DIR is unset
+	share.seal.sys.UpdatePermType(system.User, share.sc.RuntimePath, acl.Execute)
+}
+
+// instance returns a process-specific share path within tmpdir
+func (share *shareHost) instance() string {
+	if share.sharePath != "" {
+		return share.sharePath
+	}
+	share.sharePath = path.Join(share.sc.SharePath, share.seal.id.String())
+	share.seal.sys.Ephemeral(system.Process, share.sharePath, 0711)
+	return share.sharePath
+}
+
+// runtime returns a process-specific share path within XDG_RUNTIME_DIR
+func (share *shareHost) runtime() string {
+	if share.runtimeSharePath != "" {
+		return share.runtimeSharePath
+	}
+	share.ensureRuntimeDir()
+	share.runtimeSharePath = path.Join(share.sc.RunDirPath, share.seal.id.String())
+	share.seal.sys.Ephemeral(system.Process, share.runtimeSharePath, 0700)
+	share.seal.sys.UpdatePerm(share.runtimeSharePath, acl.Execute)
+	return share.runtimeSharePath
+}
+
 // fsuUser stores post-fsu credentials and metadata
 type fsuUser struct {
 	// application id
@@ -110,11 +156,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 	}
 	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)
@@ -131,10 +172,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 			fmt.Sprintf("aid %d out of range", config.Confinement.AppID))
 	}
 
-	/*
-		Resolve post-fsu user state
-	*/
-
 	seal.user = fsuUser{
 		aid:      newInt(config.Confinement.AppID),
 		data:     config.Confinement.Outer,
@@ -170,9 +207,14 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 	}
 
-	/*
-		Resolve initial container state
-	*/
+	// this also falls back to host path if encountering an invalid path
+	if !path.IsAbs(config.Confinement.Shell) {
+		config.Confinement.Shell = "/bin/sh"
+		if s, ok := sys.LookupEnv(shell); ok && path.IsAbs(s) {
+			config.Confinement.Shell = s
+		}
+	}
+	// do not use the value of shell before this point
 
 	// permissive defaults
 	if config.Confinement.Sandbox == nil {
@@ -187,7 +229,7 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 					config.Path = p
 				}
 			} else {
-				config.Path = shellPath
+				config.Path = config.Confinement.Shell
 			}
 		}
 
@@ -255,40 +297,11 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		mapuid = newInt(uid)
 		mapgid = newInt(gid)
 		if seal.env == nil {
-			seal.env = make(map[string]string)
+			seal.env = make(map[string]string, 1<<6)
 		}
 	}
 
-	/*
-		Initialise externals
-	*/
-
-	sc := sys.Paths()
-	seal.runDirPath = sc.RunDirPath
-	seal.sys = system.New(seal.user.uid.unwrap())
-
-	/*
-		Work directories
-	*/
-
-	// base fortify share path
-	seal.sys.Ensure(sc.SharePath, 0711)
-
-	// outer paths used by the main process
-	seal.sys.Ensure(sc.RunDirPath, 0700)
-	seal.sys.UpdatePermType(system.User, sc.RunDirPath, acl.Execute)
-	seal.sys.Ensure(sc.RuntimePath, 0700) // ensure this dir in case XDG_RUNTIME_DIR is unset
-	seal.sys.UpdatePermType(system.User, sc.RuntimePath, acl.Execute)
-
-	// outer process-specific share directory
-	sharePath := path.Join(sc.SharePath, seal.id.String())
-	seal.sys.Ephemeral(system.Process, sharePath, 0711)
-	// similar to share but within XDG_RUNTIME_DIR
-	sharePathLocal := path.Join(sc.RunDirPath, seal.id.String())
-	seal.sys.Ephemeral(system.Process, sharePathLocal, 0700)
-	seal.sys.UpdatePerm(sharePathLocal, acl.Execute)
-
-	// inner XDG_RUNTIME_DIR default formatting of `/run/user/%d` as post-fsu user
+	// inner XDG_RUNTIME_DIR default formatting of `/run/user/%d` as mapped uid
 	innerRuntimeDir := path.Join("/run/user", mapuid.String())
 	seal.container.Tmpfs("/run/user", 1<<12, 0755)
 	seal.container.Tmpfs(innerRuntimeDir, 1<<23, 0700)
@@ -296,44 +309,44 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 	seal.env[xdgSessionClass] = "user"
 	seal.env[xdgSessionType] = "tty"
 
-	// outer path for inner /tmp
+	share := &shareHost{seal: seal, sc: sys.Paths()}
+	seal.runDirPath = share.sc.RunDirPath
+	seal.sys = system.New(seal.user.uid.unwrap())
+
 	{
-		tmpdir := path.Join(sc.SharePath, "tmpdir")
+		seal.sys.Ensure(share.sc.SharePath, 0711)
+		tmpdir := path.Join(share.sc.SharePath, "tmpdir")
 		seal.sys.Ensure(tmpdir, 0700)
 		seal.sys.UpdatePermType(system.User, tmpdir, acl.Execute)
 		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)
+		// mount inner /tmp from share so it shares persistence and storage behaviour of host /tmp
 		seal.container.Bind(tmpdirInst, "/tmp", sandbox.BindWritable)
 	}
 
-	/*
-		Passwd database
-	*/
+	{
+		homeDir := "/var/empty"
+		if seal.user.home != "" {
+			homeDir = seal.user.home
+		}
+		username := "chronos"
+		if seal.user.username != "" {
+			username = seal.user.username
+		}
+		seal.container.Bind(seal.user.data, homeDir, sandbox.BindWritable)
+		seal.container.Dir = homeDir
+		seal.env["HOME"] = homeDir
+		seal.env["USER"] = username
+		seal.env[shell] = config.Confinement.Shell
 
-	homeDir := "/var/empty"
-	if seal.user.home != "" {
-		homeDir = seal.user.home
+		seal.container.Place("/etc/passwd",
+			[]byte(username+":x:"+mapuid.String()+":"+mapgid.String()+":Fortify:"+homeDir+":"+config.Confinement.Shell+"\n"))
+		seal.container.Place("/etc/group",
+			[]byte("fortify:x:"+mapgid.String()+":\n"))
 	}
-	username := "chronos"
-	if seal.user.username != "" {
-		username = seal.user.username
-	}
-	seal.container.Bind(seal.user.data, homeDir, sandbox.BindWritable)
-	seal.container.Dir = homeDir
-	seal.env["HOME"] = homeDir
-	seal.env["USER"] = username
 
-	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 for proper terminal I/O in shell
+	// pass TERM for proper terminal I/O in initial process
 	if t, ok := sys.LookupEnv(term); ok {
 		seal.env[term] = t
 	}
@@ -343,9 +356,9 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		var socketPath string
 		if name, ok := sys.LookupEnv(wl.WaylandDisplay); !ok {
 			fmsg.Verbose(wl.WaylandDisplay + " is not set, assuming " + wl.FallbackName)
-			socketPath = path.Join(sc.RuntimePath, wl.FallbackName)
+			socketPath = path.Join(share.sc.RuntimePath, wl.FallbackName)
 		} else if !path.IsAbs(name) {
-			socketPath = path.Join(sc.RuntimePath, name)
+			socketPath = path.Join(share.sc.RuntimePath, name)
 		} else {
 			socketPath = name
 		}
@@ -354,18 +367,18 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		seal.env[wl.WaylandDisplay] = wl.FallbackName
 
 		if !config.Confinement.Sandbox.DirectWayland { // set up security-context-v1
-			socketDir := path.Join(sc.SharePath, "wayland")
-			outerPath := path.Join(socketDir, seal.id.String())
-			seal.sys.Ensure(socketDir, 0711)
 			appID := config.ID
 			if appID == "" {
 				// use instance ID in case app id is not set
 				appID = "uk.gensokyo.fortify." + seal.id.String()
 			}
+			// downstream socket paths
+			outerPath := path.Join(share.instance(), "wayland")
 			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")
+			share.ensureRuntimeDir()
 			seal.container.Bind(socketPath, innerPath, 0)
 			seal.sys.UpdatePermType(system.EWayland, socketPath, acl.Read, acl.Write, acl.Execute)
 		}
@@ -382,13 +395,9 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 	}
 
-	/*
-		PulseAudio server and authentication
-	*/
-
 	if config.Confinement.Enablements&system.EPulse != 0 {
 		// PulseAudio runtime directory (usually `/run/user/%d/pulse`)
-		pulseRuntimeDir := path.Join(sc.RuntimePath, "pulse")
+		pulseRuntimeDir := path.Join(share.sc.RuntimePath, "pulse")
 		// PulseAudio socket (usually `/run/user/%d/pulse/native`)
 		pulseSocket := path.Join(pulseRuntimeDir, "native")
 
@@ -416,7 +425,7 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 
 		// hard link pulse socket into target-executable share
-		innerPulseRuntimeDir := path.Join(sharePathLocal, "pulse")
+		innerPulseRuntimeDir := path.Join(share.runtime(), "pulse")
 		innerPulseSocket := path.Join(innerRuntimeDir, "pulse", "native")
 		seal.sys.Link(pulseSocket, innerPulseRuntimeDir)
 		seal.container.Bind(innerPulseRuntimeDir, innerPulseSocket, 0)
@@ -435,10 +444,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 	}
 
-	/*
-		D-Bus proxy
-	*/
-
 	if config.Confinement.Enablements&system.EDBus != 0 {
 		// ensure dbus session bus defaults
 		if config.Confinement.SessionBus == nil {
@@ -446,6 +451,7 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 
 		// downstream socket paths
+		sharePath := share.instance()
 		sessionPath, systemPath := path.Join(sharePath, "bus"), path.Join(sharePath, "system_bus_socket")
 
 		// configure dbus proxy
@@ -471,10 +477,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 		}
 	}
 
-	/*
-		Miscellaneous
-	*/
-
 	for _, dest := range config.Confinement.Sandbox.Cover {
 		seal.container.Tmpfs(dest, 1<<13, 0755)
 	}
@@ -504,7 +506,13 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *fst.Co
 
 	// 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 })
+	for k, v := range seal.env {
+		if strings.IndexByte(k, '=') != -1 {
+			return fmsg.WrapError(syscall.EINVAL,
+				fmt.Sprintf("invalid environment variable %s", k))
+		}
+		seal.container.Env = append(seal.container.Env, k+"="+v)
+	}
 	slices.Sort(seal.container.Env)
 
 	fmsg.Verbosef("created application seal for uid %s (%s) groups: %v, argv: %s",

internal/state/multi.go

@@ -33,10 +33,10 @@ func (s *multiStore) Do(aid int, f func(c Cursor)) (bool, error) {
 
 	// load or initialise new backend
 	b := new(multiBackend)
+	b.lock.Lock()
 	if v, ok := s.backends.LoadOrStore(aid, b); ok {
 		b = v.(*multiBackend)
 	} else {
-		b.lock.Lock()
 		b.path = path.Join(s.base, strconv.Itoa(aid))
 
 		// ensure directory

internal/sys/interface.go

@@ -47,7 +47,7 @@ type State interface {
 	Uid(aid int) (int, error)
 }
 
-// CopyPaths is a generic implementation of [System.Paths].
+// CopyPaths is a generic implementation of [fst.Paths].
 func CopyPaths(os State, v *fst.Paths) {
 	v.SharePath = path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Getuid()))
 

nixos.nix

@@ -88,11 +88,15 @@ in
 
                   conf = {
                     inherit (app) id;
-                    path = pkgs.writeScript "${app.name}-start" ''
-                      #!${pkgs.zsh}${pkgs.zsh.shellPath}
-                      ${script}
-                    '';
-                    args = [ "${app.name}-start" ];
+                    path =
+                      if app.path == null then
+                        pkgs.writeScript "${app.name}-start" ''
+                          #!${pkgs.zsh}${pkgs.zsh.shellPath}
+                          ${script}
+                        ''
+                      else
+                        app.path;
+                    args = if app.args == null then [ "${app.name}-start" ] else app.args;
 
                     confinement = {
                       app_id = aid;
@@ -197,9 +201,11 @@ in
                   ${copy "${pkg}/share/icons"}
                   ${copy "${pkg}/share/man"}
 
-                  substituteInPlace $out/share/applications/* \
-                    --replace-warn '${pkg}/bin/' "" \
-                    --replace-warn '${pkg}/libexec/' ""
+                  if test -d "$out/share/applications"; then
+                    substituteInPlace $out/share/applications/* \
+                      --replace-warn '${pkg}/bin/' "" \
+                      --replace-warn '${pkg}/libexec/' ""
+                  fi
                 ''
               )
               ++ acc

options.md

@@ -35,7 +35,7 @@ package
 
 
 *Default:*
-` <derivation fortify-static-x86_64-unknown-linux-musl-0.3.1> `
+` <derivation fortify-static-x86_64-unknown-linux-musl-0.3.3> `
 
 
 
@@ -73,6 +73,25 @@ list of package
 
 
 
+## environment\.fortify\.apps\.\*\.args
+
+
+
+Custom args\.
+Setting this to null will default to script name\.
+
+
+
+*Type:*
+null or (list of string)
+
+
+
+*Default:*
+` null `
+
+
+
 ## environment\.fortify\.apps\.\*\.capability\.dbus
 
 
@@ -486,6 +505,25 @@ boolean
 
 
 
+## environment\.fortify\.apps\.\*\.path
+
+
+
+Custom executable path\.
+Setting this to null will default to the start script\.
+
+
+
+*Type:*
+null or string
+
+
+
+*Default:*
+` null `
+
+
+
 ## environment\.fortify\.apps\.\*\.script
 
 
@@ -606,7 +644,7 @@ package
 
 
 *Default:*
-` <derivation fortify-fsu-0.3.1> `
+` <derivation fortify-fsu-0.3.3> `
 
 
 

options.nix

@@ -94,6 +94,24 @@ in
                 '';
               };
 
+              path = mkOption {
+                type = nullOr str;
+                default = null;
+                description = ''
+                  Custom executable path.
+                  Setting this to null will default to the start script.
+                '';
+              };
+
+              args = mkOption {
+                type = nullOr (listOf str);
+                default = null;
+                description = ''
+                  Custom args.
+                  Setting this to null will default to script name.
+                '';
+              };
+
               script = mkOption {
                 type = nullOr str;
                 default = null;

package.nix

@@ -31,7 +31,7 @@
 
 buildGoModule rec {
   pname = "fortify";
-  version = "0.3.1";
+  version = "0.3.3";
 
   src = builtins.path {
     name = "${pname}-src";

print.go

@@ -77,7 +77,9 @@ func printShowInstance(
 	if len(config.Confinement.Groups) > 0 {
 		t.Printf(" Groups:\t%q\n", config.Confinement.Groups)
 	}
-	t.Printf(" Directory:\t%s\n", config.Confinement.Outer)
+	if config.Confinement.Outer != "" {
+		t.Printf(" Directory:\t%s\n", config.Confinement.Outer)
+	}
 	if config.Confinement.Sandbox != nil {
 		sandbox := config.Confinement.Sandbox
 		if sandbox.Hostname != "" {
@@ -114,7 +116,12 @@ func printShowInstance(
 		// Env           map[string]string   `json:"env"`
 		// Link          [][2]string         `json:"symlink"`
 	}
-	t.Printf(" Command:\t%s\n", strings.Join(config.Args, " "))
+	if config.Confinement.Sandbox != nil {
+		t.Printf(" Path:\t%s\n", config.Path)
+	}
+	if len(config.Args) > 0 {
+		t.Printf(" Arguments:\t%s\n", strings.Join(config.Args, " "))
+	}
 	t.Printf("\n")
 
 	if !short {
@@ -247,22 +254,18 @@ func printPs(output io.Writer, now time.Time, s state.Store, short, flagJSON boo
 	t := newPrinter(output)
 	defer t.MustFlush()
 
-	t.Println("\tInstance\tPID\tApp\tUptime\tEnablements\tCommand")
+	t.Println("\tInstance\tPID\tApplication\tUptime")
 	for _, e := range exp {
-		var (
-			es = "(No confinement information)"
-			cs = "(No command information)"
-			as = "(No configuration information)"
-		)
+		as := "(No configuration information)"
 		if e.Config != nil {
-			es = e.Config.Confinement.Enablements.String()
-			cs = fmt.Sprintf("%q", e.Config.Args)
 			as = strconv.Itoa(e.Config.Confinement.AppID)
+			if e.Config.ID != "" {
+				as += " (" + e.Config.ID + ")"
+			}
 		}
-		t.Printf("\t%s\t%d\t%s\t%s\t%s\t%s\n",
-			e.s[:8], e.PID, as, now.Sub(e.Time).Round(time.Second).String(), strings.TrimPrefix(es, ", "), cs)
+		t.Printf("\t%s\t%d\t%s\t%s\n",
+			e.s[:8], e.PID, as, now.Sub(e.Time).Round(time.Second).String())
 	}
-	t.Println()
 }
 
 type expandedStateEntry struct {

print_test.go

@@ -44,7 +44,8 @@ func Test_printShowInstance(t *testing.T) {
  Flags:          userns net dev tty mapuid autoetc
  Etc:            /etc
  Cover:          /var/run/nscd
- Command:        chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
+ Path:           /run/current-system/sw/bin/chromium
+ Arguments:      chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
 
 Filesystem
  +/nix/store
@@ -75,26 +76,22 @@ System bus
 App
  ID:             0
  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)
- Directory:      
  Flags:          none
  Etc:            /etc
- Command:        
+ Path:           
 
 `},
 		{"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)
- Directory:      
  Flags:          none
  Etc:            /etc
- Command:        
+ Path:           
 
 Filesystem
 
@@ -106,8 +103,6 @@ Extra ACL
 App
  ID:             0
  Enablements:    (no enablements)
- Directory:      
- Command:        
 
 Session bus
  Filter:    false
@@ -128,7 +123,8 @@ App
  Flags:          userns net dev tty mapuid autoetc
  Etc:            /etc
  Cover:          /var/run/nscd
- Command:        chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
+ Path:           /run/current-system/sw/bin/chromium
+ Arguments:      chromium --ignore-gpu-blocklist --disable-smooth-scrolling --enable-features=UseOzonePlatform --ozone-platform=wayland
 
 Filesystem
  +/nix/store
@@ -163,8 +159,6 @@ State
 App
  ID:             0
  Enablements:    (no enablements)
- Directory:      
- Command:        
 
 `},
 
@@ -208,6 +202,7 @@ App
       "username": "chronos",
       "home_inner": "/var/lib/fortify",
       "home": "/var/lib/persist/home/org.chromium.Chromium",
+      "shell": "/run/current-system/sw/bin/zsh",
       "sandbox": {
         "hostname": "localhost",
         "seccomp": 32,
@@ -332,6 +327,7 @@ App
     "username": "chronos",
     "home_inner": "/var/lib/fortify",
     "home": "/var/lib/persist/home/org.chromium.Chromium",
+    "shell": "/run/current-system/sw/bin/zsh",
     "sandbox": {
       "hostname": "localhost",
       "seccomp": 32,
@@ -458,20 +454,16 @@ func Test_printPs(t *testing.T) {
 		short, json bool
 		want        string
 	}{
-		{"no entries", make(state.Entries), false, false, `    Instance    PID    App    Uptime    Enablements    Command
-
+		{"no entries", make(state.Entries), false, false, `    Instance    PID    Application    Uptime
 `},
 		{"no entries short", make(state.Entries), true, false, ``},
-		{"nil instance", state.Entries{testID: nil}, false, false, `    Instance    PID    App    Uptime    Enablements    Command
-
+		{"nil instance", state.Entries{testID: nil}, false, false, `    Instance    PID    Application    Uptime
 `},
-		{"state corruption", state.Entries{fst.ID{}: testState}, false, false, `    Instance    PID    App    Uptime    Enablements    Command
-
+		{"state corruption", state.Entries{fst.ID{}: testState}, false, false, `    Instance    PID    Application    Uptime
 `},
 
-		{"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", state.Entries{testID: testState}, false, false, `    Instance    PID           Application                  Uptime
+    8e2c76b0    3735928559    9 (org.chromium.Chromium)    1h2m32s
 `},
 		{"valid short", state.Entries{testID: testState}, true, false, `8e2c76b0
 `},
@@ -514,6 +506,7 @@ func Test_printPs(t *testing.T) {
         "username": "chronos",
         "home_inner": "/var/lib/fortify",
         "home": "/var/lib/persist/home/org.chromium.Chromium",
+        "shell": "/run/current-system/sw/bin/zsh",
         "sandbox": {
           "hostname": "localhost",
           "seccomp": 32,

sandbox/container.go

@@ -99,19 +99,11 @@ type (
 		// Permission bits of newly created parent directories.
 		// The zero value is interpreted as 0755.
 		ParentPerm os.FileMode
+		// Retain CAP_SYS_ADMIN.
+		Privileged bool
 
 		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 {

sandbox/init.go

@@ -45,10 +45,6 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 		log.Fatal("this process must run as pid 1")
 	}
 
-	/*
-		receive setup payload
-	*/
-
 	var (
 		params      initParams
 		closeSetup  func() error
@@ -111,10 +107,6 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 	// 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 {
@@ -155,6 +147,7 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 	if err := os.Mkdir(hostDir, 0755); err != nil {
 		log.Fatalf("%v", err)
 	}
+	// pivot_root uncovers basePath in hostDir
 	if err := syscall.PivotRoot(basePath, hostDir); err != nil {
 		log.Fatalf("cannot pivot into intermediate root: %v", err)
 	}
@@ -173,10 +166,7 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 		}
 	}
 
-	/*
-		pivot to sysroot
-	*/
-
+	// setup requiring host root complete at this point
 	if err := syscall.Mount(hostDir, hostDir, "",
 		syscall.MS_SILENT|syscall.MS_REC|syscall.MS_PRIVATE,
 		""); err != nil {
@@ -216,24 +206,33 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 		}
 	}
 
-	/*
-		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 params.Privileged && i == CAP_SYS_ADMIN {
+			continue
+		}
 		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)
 		}
 	}
+
+	var keep [2]uint32
+	if params.Privileged {
+		keep[capToIndex(CAP_SYS_ADMIN)] |= capToMask(CAP_SYS_ADMIN)
+
+		if _, _, errno := syscall.Syscall(syscall.SYS_PRCTL, PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_SYS_ADMIN); errno != 0 {
+			log.Fatalf("cannot raise CAP_SYS_ADMIN: %v", errno)
+		}
+	}
 	if err := capset(
 		&capHeader{_LINUX_CAPABILITY_VERSION_3, 0},
-		&[2]capData{{0, 0, 0}, {0, 0, 0}},
+		&[2]capData{{0, keep[0], keep[0]}, {0, keep[1], keep[1]}},
 	); err != nil {
 		log.Fatalf("cannot capset: %v", err)
 	}
@@ -242,20 +241,13 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 		log.Fatalf("cannot load syscall filter: %v", err)
 	}
 
-	/*
-		pass through extra files
-	*/
-
 	extraFiles := make([]*os.File, params.Count)
 	for i := range extraFiles {
+		// setup fd is placed before all extra files
 		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
@@ -268,22 +260,11 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 	}
 	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
@@ -320,6 +301,10 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 		close(done)
 	}()
 
+	// handle signals to dump withheld messages
+	sig := make(chan os.Signal, 2)
+	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+
 	// closed after residualProcessTimeout has elapsed after initial process death
 	timeout := make(chan struct{})
 
@@ -332,7 +317,6 @@ func Init(prepare func(prefix string), setVerbose func(verbose bool)) {
 			} else {
 				msg.Verbosef("terminating on %s", s.String())
 			}
-			msg.BeforeExit()
 			os.Exit(0)
 		case w := <-info:
 			if w.wpid == cmd.Process.Pid {

sandbox/ops.go

@@ -13,6 +13,22 @@ import (
 	"unsafe"
 )
 
+type (
+	Ops []Op
+	Op  interface {
+		// early is called in host root.
+		early(params *Params) error
+		// apply is called in intermediate root.
+		apply(params *Params) error
+
+		prefix() string
+		Is(op Op) bool
+		fmt.Stringer
+	}
+)
+
+func (f *Ops) Grow(n int) { *f = slices.Grow(*f, n) }
+
 func init() { gob.Register(new(BindMount)) }
 
 // BindMount bind mounts host path Source on container path Target.

sandbox/seccomp/export_test.go

@@ -73,6 +73,16 @@ func TestExport(t *testing.T) {
 			0x80, 0x8b, 0x1a, 0x6f, 0x84, 0xf3, 0x2b, 0xbd,
 			0xe1, 0xaa, 0x02, 0xae, 0x30, 0xee, 0xdc, 0xfa,
 		}, false},
+		{"fortify default", seccomp.FlagExt | seccomp.FlagDenyDevel, []byte{
+			0xc6, 0x98, 0xb0, 0x81, 0xff, 0x95, 0x7a, 0xfe,
+			0x17, 0xa6, 0xd9, 0x43, 0x74, 0x53, 0x7d, 0x37,
+			0xf2, 0xa6, 0x3f, 0x6f, 0x9d, 0xd7, 0x5d, 0xa7,
+			0x54, 0x65, 0x42, 0x40, 0x7a, 0x9e, 0x32, 0x47,
+			0x6e, 0xbd, 0xa3, 0x31, 0x2b, 0xa7, 0x78, 0x5d,
+			0x7f, 0x61, 0x85, 0x42, 0xbc, 0xfa, 0xf2, 0x7c,
+			0xa2, 0x7d, 0xcc, 0x2d, 0xdd, 0xba, 0x85, 0x20,
+			0x69, 0xd2, 0x8b, 0xcf, 0xe8, 0xca, 0xd3, 0x9a,
+		}, false},
 	}
 
 	buf := make([]byte, 8)

sandbox/seccomp/seccomp.go

@@ -1,3 +1,4 @@
+// Package seccomp provides filter presets and high level wrappers around libseccomp.
 package seccomp
 
 /*

sandbox/syscall.go

@@ -11,6 +11,7 @@ const (
 	PR_SET_NO_NEW_PRIVS = 0x26
 
 	CAP_SYS_ADMIN = 0x15
+	CAP_SETPCAP   = 0x8
 )
 
 const (
@@ -30,10 +31,9 @@ func SetDumpable(dumpable uintptr) error {
 const (
 	_LINUX_CAPABILITY_VERSION_3 = 0x20080522
 
-	PR_CAP_AMBIENT           = 47
-	PR_CAP_AMBIENT_CLEAR_ALL = 4
-
-	CAP_SETPCAP = 8
+	PR_CAP_AMBIENT           = 0x2f
+	PR_CAP_AMBIENT_RAISE     = 0x2
+	PR_CAP_AMBIENT_CLEAR_ALL = 0x4
 )
 
 type (
@@ -49,6 +49,12 @@ type (
 	}
 )
 
+// See CAP_TO_INDEX in linux/capability.h:
+func capToIndex(cap uintptr) uintptr { return cap >> 5 }
+
+// See CAP_TO_MASK in linux/capability.h:
+func capToMask(cap uintptr) uint32 { return 1 << uint(cap&31) }
+
 func capset(hdrp *capHeader, datap *[2]capData) error {
 	if _, _, errno := syscall.Syscall(syscall.SYS_CAPSET,
 		uintptr(unsafe.Pointer(hdrp)),

test/configuration.nix

@@ -4,12 +4,6 @@
   config,
   ...
 }:
-let
-  testCases = import ./sandbox/case {
-    inherit (pkgs) lib callPackage foot;
-    inherit (config.environment.fortify.package) version;
-  };
-in
 {
   users.users = {
     alice = {
@@ -108,10 +102,6 @@ in
     home-manager = _: _: { home.stateVersion = "23.05"; };
 
     apps = [
-      testCases.preset
-      testCases.tty
-      testCases.mapuid
-
       {
         name = "ne-foot";
         verbose = true;

test/sandbox/assert.go

@@ -7,10 +7,15 @@ in the public sandbox/vfs package. Files in this package are excluded by the bui
 package sandbox
 
 import (
+	"crypto/sha512"
+	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"io/fs"
 	"log"
 	"os"
+	"syscall"
+	"time"
 )
 
 var (
@@ -23,6 +28,7 @@ func printf(format string, v ...any) { printfFunc(format, v...) }
 func fatalf(format string, v ...any) { fatalfFunc(format, v...) }
 
 type TestCase struct {
+	Env     []string          `json:"env"`
 	FS      *FS               `json:"fs"`
 	Mount   []*MountinfoEntry `json:"mount"`
 	Seccomp bool              `json:"seccomp"`
@@ -34,13 +40,46 @@ type T struct {
 	MountsPath string
 }
 
-func (t *T) MustCheckFile(wantFilePath string) {
+func (t *T) MustCheckFile(wantFilePath, markerPath string) {
 	var want *TestCase
 	mustDecode(wantFilePath, &want)
 	t.MustCheck(want)
+	if _, err := os.Create(markerPath); err != nil {
+		fatalf("cannot create success marker: %v", err)
+	}
 }
 
 func (t *T) MustCheck(want *TestCase) {
+	if want.Env != nil {
+		var (
+			fail bool
+			i    int
+			got  string
+		)
+		for i, got = range os.Environ() {
+			if i == len(want.Env) {
+				fatalf("got more than %d environment variables", len(want.Env))
+			}
+			if got != want.Env[i] {
+				fail = true
+				printf("[FAIL] %s", got)
+			} else {
+				printf("[ OK ] %s", got)
+			}
+		}
+
+		i++
+		if i != len(want.Env) {
+			fatalf("got %d environment variables, want %d", i, len(want.Env))
+		}
+
+		if fail {
+			fatalf("[FAIL] some environment variables did not match")
+		}
+	} else {
+		printf("[SKIP] skipping environ check")
+	}
+
 	if want.FS != nil && t.FS != nil {
 		if err := want.FS.Compare(".", t.FS); err != nil {
 			fatalf("%v", err)
@@ -82,7 +121,7 @@ func (t *T) MustCheck(want *TestCase) {
 	}
 
 	if want.Seccomp {
-		if TrySyscalls() != nil {
+		if trySyscalls() != nil {
 			os.Exit(1)
 		}
 	} else {
@@ -90,6 +129,81 @@ func (t *T) MustCheck(want *TestCase) {
 	}
 }
 
+func MustCheckFilter(pid int, want string) {
+	err := CheckFilter(pid, want)
+	if err == nil {
+		return
+	}
+
+	var perr *ptraceError
+	if !errors.As(err, &perr) {
+		fatalf("%s", err)
+	}
+	switch perr.op {
+	case "PTRACE_ATTACH":
+		fatalf("cannot attach to process %d: %v", pid, err)
+	case "PTRACE_SECCOMP_GET_FILTER":
+		if perr.errno == syscall.ENOENT {
+			fatalf("seccomp filter not installed for process %d", pid)
+		}
+		fatalf("cannot get filter: %v", err)
+	default:
+		fatalf("cannot check filter: %v", err)
+	}
+
+	*(*int)(nil) = 0 // not reached
+}
+
+func CheckFilter(pid int, want string) error {
+	if err := ptraceAttach(pid); err != nil {
+		return err
+	}
+	defer func() {
+		if err := ptraceDetach(pid); err != nil {
+			printf("cannot detach from process %d: %v", pid, err)
+		}
+	}()
+
+	h := sha512.New()
+	{
+	getFilter:
+		buf, err := getFilter[[8]byte](pid, 0)
+		/* this is not how ESRCH should be handled: the manpage advises the
+		use of waitpid, however that is not applicable for attaching to an
+		arbitrary process, and spawning target process here is not easily
+		possible under the current testing framework;
+
+		despite checking for /proc/pid/status indicating state t (tracing stop),
+		it does not appear to be directly related to the internal state used to
+		determine whether a process is ready to accept ptrace operations, it also
+		introduces a TOCTOU that is irrelevant in the testing vm; this behaviour
+		is kept anyway as it reduces the average iterations required here;
+
+		since this code is only ever compiled into the test program, whatever
+		implications this ugliness might have should not hurt anyone */
+		if errors.Is(err, syscall.ESRCH) {
+			time.Sleep(100 * time.Millisecond)
+			goto getFilter
+		}
+
+		if err != nil {
+			return err
+		}
+
+		for _, b := range buf {
+			h.Write(b[:])
+		}
+	}
+
+	if got := hex.EncodeToString(h.Sum(nil)); got != want {
+		printf("[FAIL] %s", got)
+		return syscall.ENOTRECOVERABLE
+	} else {
+		printf("[ OK ] %s", got)
+		return nil
+	}
+}
+
 func mustDecode(wantFilePath string, v any) {
 	if f, err := os.Open(wantFilePath); err != nil {
 		fatalf("cannot open %q: %v", wantFilePath, err)

test/sandbox/assert.nix

@@ -1,30 +0,0 @@
-{
-  writeText,
-  buildGoModule,
-  pkg-config,
-  util-linux,
-
-  version,
-}:
-buildGoModule {
-  pname = "check-sandbox";
-  inherit version;
-
-  src = ../.;
-  vendorHash = null;
-
-  buildInputs = [ util-linux ];
-  nativeBuildInputs = [ pkg-config ];
-
-  preBuild = ''
-    go mod init git.gensokyo.uk/security/fortify/test >& /dev/null
-    cp ${writeText "main.go" ''
-      package main
-
-      import "os"
-      import "git.gensokyo.uk/security/fortify/test/sandbox"
-
-      func main() { (&sandbox.T{FS: os.DirFS("/")}).MustCheckFile(os.Args[1]) }
-    ''} main.go
-  '';
-}

test/sandbox/case/default.nix

@@ -1,10 +1,4 @@
-{
-  lib,
-  callPackage,
-  foot,
-
-  version,
-}:
+lib: testProgram:
 let
   fs = mode: dir: data: {
     mode = lib.fromHexString mode;
@@ -29,8 +23,6 @@ let
       ;
   };
 
-  checkSandbox = callPackage ../. { inherit version; };
-
   callTestCase =
     path:
     let
@@ -46,9 +38,13 @@ let
       name = "check-sandbox-${tc.name}";
       verbose = true;
       inherit (tc) tty mapRealUid;
-      share = foot;
+      share = testProgram;
       packages = [ ];
-      command = builtins.toString (checkSandbox tc.name tc.want);
+      path = "${testProgram}/bin/fortify-test";
+      args = [
+        "test"
+        (toString (builtins.toFile "fortify-${tc.name}-want.json" (builtins.toJSON tc.want)))
+      ];
     };
 in
 {

test/sandbox/case/mapuid.nix

@@ -9,6 +9,19 @@
   mapRealUid = true;
 
   want = {
+    env = [
+      "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus"
+      "HOME=/var/lib/fortify/u0/a3"
+      "PULSE_SERVER=unix:/run/user/1000/pulse/native"
+      "SHELL=/run/current-system/sw/bin/bash"
+      "TERM=linux"
+      "USER=u0_a3"
+      "WAYLAND_DISPLAY=wayland-0"
+      "XDG_RUNTIME_DIR=/run/user/1000"
+      "XDG_SESSION_CLASS=user"
+      "XDG_SESSION_TYPE=tty"
+    ];
+
     fs = fs "dead" {
       ".fortify" = fs "800001ed" {
         etc = fs "800001ed" null null;
@@ -84,7 +97,6 @@
         "pki" = fs "80001ff" null null;
         "polkit-1" = fs "80001ff" null null;
         "profile" = fs "80001ff" null null;
-        "profiles" = fs "80001ff" null null;
         "protocols" = fs "80001ff" null null;
         "resolv.conf" = fs "80001ff" null null;
         "resolvconf.conf" = fs "80001ff" null null;

test/sandbox/case/preset.nix

@@ -9,6 +9,19 @@
   mapRealUid = false;
 
   want = {
+    env = [
+      "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/65534/bus"
+      "HOME=/var/lib/fortify/u0/a1"
+      "PULSE_SERVER=unix:/run/user/65534/pulse/native"
+      "SHELL=/run/current-system/sw/bin/bash"
+      "TERM=linux"
+      "USER=u0_a1"
+      "WAYLAND_DISPLAY=wayland-0"
+      "XDG_RUNTIME_DIR=/run/user/65534"
+      "XDG_SESSION_CLASS=user"
+      "XDG_SESSION_TYPE=tty"
+    ];
+
     fs = fs "dead" {
       ".fortify" = fs "800001ed" {
         etc = fs "800001ed" null null;
@@ -84,7 +97,6 @@
         "pki" = fs "80001ff" null null;
         "polkit-1" = fs "80001ff" null null;
         "profile" = fs "80001ff" null null;
-        "profiles" = fs "80001ff" null null;
         "protocols" = fs "80001ff" null null;
         "resolv.conf" = fs "80001ff" null null;
         "resolvconf.conf" = fs "80001ff" null null;

test/sandbox/case/tty.nix

@@ -9,6 +9,19 @@
   mapRealUid = false;
 
   want = {
+    env = [
+      "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/65534/bus"
+      "HOME=/var/lib/fortify/u0/a2"
+      "PULSE_SERVER=unix:/run/user/65534/pulse/native"
+      "SHELL=/run/current-system/sw/bin/bash"
+      "TERM=linux"
+      "USER=u0_a2"
+      "WAYLAND_DISPLAY=wayland-0"
+      "XDG_RUNTIME_DIR=/run/user/65534"
+      "XDG_SESSION_CLASS=user"
+      "XDG_SESSION_TYPE=tty"
+    ];
+
     fs = fs "dead" {
       ".fortify" = fs "800001ed" {
         etc = fs "800001ed" null null;
@@ -85,7 +98,6 @@
         "pki" = fs "80001ff" null null;
         "polkit-1" = fs "80001ff" null null;
         "profile" = fs "80001ff" null null;
-        "profiles" = fs "80001ff" null null;
         "protocols" = fs "80001ff" null null;
         "resolv.conf" = fs "80001ff" null null;
         "resolvconf.conf" = fs "80001ff" null null;

test/sandbox/configuration.nix

@@ -0,0 +1,76 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+let
+  testProgram = pkgs.callPackage ./tool/package.nix { inherit (config.environment.fortify.package) version; };
+  testCases = import ./case lib testProgram;
+in
+{
+  users.users = {
+    alice = {
+      isNormalUser = true;
+      description = "Alice Foobar";
+      password = "foobar";
+      uid = 1000;
+    };
+  };
+
+  home-manager.users.alice.home.stateVersion = "24.11";
+
+  # Automatically login on tty1 as a normal user:
+  services.getty.autologinUser = "alice";
+
+  environment = {
+    systemPackages = with pkgs; [
+      # For checking seccomp outcome:
+      testProgram
+    ];
+
+    variables = {
+      SWAYSOCK = "/tmp/sway-ipc.sock";
+      WLR_RENDERER = "pixman";
+    };
+  };
+
+  # Automatically configure and start Sway when logging in on tty1:
+  programs.bash.loginShellInit = ''
+    if [ "$(tty)" = "/dev/tty1" ]; then
+      set -e
+
+      mkdir -p ~/.config/sway
+      (sed s/Mod4/Mod1/ /etc/sway/config &&
+      echo 'output * bg ${pkgs.nixos-artwork.wallpapers.simple-light-gray.gnomeFilePath} fill' &&
+      echo 'output Virtual-1 res 1680x1050') > ~/.config/sway/config
+
+      sway --validate
+      systemd-cat --identifier=session sway && touch /tmp/sway-exit-ok
+    fi
+  '';
+
+  programs.sway.enable = true;
+
+  virtualisation.qemu.options = [
+    # Need to switch to a different GPU driver than the default one (-vga std) so that Sway can launch:
+    "-vga none -device virtio-gpu-pci"
+
+    # Increase performance:
+    "-smp 8"
+  ];
+
+  environment.fortify = {
+    enable = true;
+    stateDir = "/var/lib/fortify";
+    users.alice = 0;
+
+    home-manager = _: _: { home.stateVersion = "23.05"; };
+
+    apps = [
+      testCases.preset
+      testCases.tty
+      testCases.mapuid
+    ];
+  };
+}

test/sandbox/default.nix

@@ -1,14 +1,39 @@
 {
-  writeShellScript,
-  writeText,
-  callPackage,
+  lib,
+  nixosTest,
 
-  version,
+  self,
+  withRace ? false,
 }:
-name: want:
-writeShellScript "fortify-${name}-check-sandbox-script" ''
-  set -e
-  ${callPackage ./assert.nix { inherit version; }}/bin/test \
-    ${writeText "fortify-${name}-want.json" (builtins.toJSON want)}
-  touch /tmp/sandbox-ok
-''
+
+nixosTest {
+  name = "fortify-sandbox" + (if withRace then "-race" else "");
+  nodes.machine =
+    { options, pkgs, ... }:
+    {
+      # Run with Go race detector:
+      environment.fortify = lib.mkIf withRace rec {
+        # race detector does not support static linking
+        package = (pkgs.callPackage ../../package.nix { }).overrideAttrs (previousAttrs: {
+          GOFLAGS = previousAttrs.GOFLAGS ++ [ "-race" ];
+        });
+        fsuPackage = options.environment.fortify.fsuPackage.default.override { fortify = package; };
+      };
+
+      imports = [
+        ./configuration.nix
+
+        self.nixosModules.fortify
+        self.inputs.home-manager.nixosModules.home-manager
+      ];
+    };
+
+  # adapted from nixos sway integration tests
+
+  # testScriptWithTypes:49: error: Cannot call function of unknown type
+  #           (machine.succeed if succeed else machine.execute)(
+  #           ^
+  # Found 1 error in 1 file (checked 1 source file)
+  skipTypeCheck = true;
+  testScript = builtins.readFile ./test.py;
+}

test/sandbox/ptrace.go

@@ -0,0 +1,119 @@
+package sandbox
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+const (
+	NULL = 0
+
+	PTRACE_ATTACH             = 16
+	PTRACE_DETACH             = 17
+	PTRACE_SECCOMP_GET_FILTER = 0x420c
+)
+
+type ptraceError struct {
+	op    string
+	errno syscall.Errno
+}
+
+func (p *ptraceError) Error() string { return fmt.Sprintf("%s: %v", p.op, p.errno) }
+
+func (p *ptraceError) Unwrap() error {
+	if p.errno == 0 {
+		return nil
+	}
+	return p.errno
+}
+
+func ptrace(op uintptr, pid, addr int, data unsafe.Pointer) (r uintptr, errno syscall.Errno) {
+	r, _, errno = syscall.Syscall6(syscall.SYS_PTRACE, op, uintptr(pid), uintptr(addr), uintptr(data), NULL, NULL)
+	return
+}
+
+func ptraceAttach(pid int) error {
+	const (
+		statePrefix = "State:"
+		stateSuffix = "t (tracing stop)"
+	)
+
+	var r io.ReadSeekCloser
+	if f, err := os.Open(fmt.Sprintf("/proc/%d/status", pid)); err != nil {
+		return err
+	} else {
+		r = f
+	}
+
+	if _, errno := ptrace(PTRACE_ATTACH, pid, 0, nil); errno != 0 {
+		return &ptraceError{"PTRACE_ATTACH", errno}
+	}
+
+	// ugly! but there does not appear to be another way
+	for {
+		time.Sleep(10 * time.Millisecond)
+
+		if _, err := r.Seek(0, io.SeekStart); err != nil {
+			return err
+		}
+		s := bufio.NewScanner(r)
+
+		var found bool
+		for s.Scan() {
+			found = strings.HasPrefix(s.Text(), statePrefix)
+			if found {
+				break
+			}
+		}
+		if err := s.Err(); err != nil {
+			return err
+		}
+
+		if !found {
+			return syscall.EBADE
+		}
+
+		if strings.HasSuffix(s.Text(), stateSuffix) {
+			break
+		}
+	}
+
+	return nil
+}
+
+func ptraceDetach(pid int) error {
+	if _, errno := ptrace(PTRACE_DETACH, pid, 0, nil); errno != 0 {
+		return &ptraceError{"PTRACE_DETACH", errno}
+	}
+	return nil
+}
+
+type sockFilter struct { /* Filter block */
+	code uint16 /* Actual filter code */
+	jt   uint8  /* Jump true */
+	jf   uint8  /* Jump false */
+	k    uint32 /* Generic multiuse field */
+}
+
+func getFilter[T comparable](pid, index int) ([]T, error) {
+	if s := unsafe.Sizeof(*new(T)); s != 8 {
+		panic(fmt.Sprintf("invalid filter block size %d", s))
+	}
+
+	var buf []T
+	if n, errno := ptrace(PTRACE_SECCOMP_GET_FILTER, pid, index, nil); errno != 0 {
+		return nil, &ptraceError{"PTRACE_SECCOMP_GET_FILTER", errno}
+	} else {
+		buf = make([]T, n)
+	}
+	if _, errno := ptrace(PTRACE_SECCOMP_GET_FILTER, pid, index, unsafe.Pointer(&buf[0])); errno != 0 {
+		return nil, &ptraceError{"PTRACE_SECCOMP_GET_FILTER", errno}
+	}
+	return buf, nil
+}

test/sandbox/seccomp.go

@@ -10,9 +10,7 @@ import (
 */
 import "C"
 
-const NULL = 0
-
-func TrySyscalls() error {
+func trySyscalls() error {
 	testCases := []struct {
 		name  string
 		errno syscall.Errno

test/sandbox/test.py

@@ -0,0 +1,71 @@
+import json
+import shlex
+
+q = shlex.quote
+
+
+def swaymsg(command: str = "", succeed=True, type="command"):
+    assert command != "" or type != "command", "Must specify command or type"
+    shell = q(f"swaymsg -t {q(type)} -- {q(command)}")
+    with machine.nested(
+            f"sending swaymsg {shell!r}" + " (allowed to fail)" * (not succeed)
+    ):
+        ret = (machine.succeed if succeed else machine.execute)(
+            f"su - alice -c {shell}"
+        )
+
+    # execute also returns a status code, but disregard.
+    if not succeed:
+        _, ret = ret
+
+    if not succeed and not ret:
+        return None
+
+    parsed = json.loads(ret)
+    return parsed
+
+
+start_all()
+machine.wait_for_unit("multi-user.target")
+
+# To check fortify's version:
+print(machine.succeed("sudo -u alice -i fortify version"))
+
+# Wait for Sway to complete startup:
+machine.wait_for_file("/run/user/1000/wayland-1")
+machine.wait_for_file("/tmp/sway-ipc.sock")
+
+# Check seccomp outcome:
+swaymsg("exec fortify run cat")
+pid = int(machine.wait_until_succeeds("pgrep -U 1000000 -x cat", timeout=5))
+print(machine.succeed(f"fortify-test filter {pid} c698b081ff957afe17a6d94374537d37f2a63f6f9dd75da7546542407a9e32476ebda3312ba7785d7f618542bcfaf27ca27dcc2dddba852069d28bcfe8cad39a &>/dev/stdout", timeout=5))
+machine.succeed(f"kill -TERM {pid}")
+
+# Verify capabilities/securebits in user namespace:
+print(machine.succeed("sudo -u alice -i fortify run capsh --print"))
+print(machine.succeed("sudo -u alice -i fortify run capsh --has-no-new-privs"))
+print(machine.fail("sudo -u alice -i fortify run capsh --has-a=CAP_SYS_ADMIN"))
+print(machine.fail("sudo -u alice -i fortify run capsh --has-b=CAP_SYS_ADMIN"))
+print(machine.fail("sudo -u alice -i fortify run capsh --has-i=CAP_SYS_ADMIN"))
+print(machine.fail("sudo -u alice -i fortify run capsh --has-p=CAP_SYS_ADMIN"))
+print(machine.fail("sudo -u alice -i fortify run umount -R /dev"))
+
+# Check sandbox outcome:
+check_offset = 0
+def check_sandbox(name):
+    global check_offset
+    check_offset += 1
+    swaymsg(f"exec script /dev/null -E always -qec check-sandbox-{name}")
+    machine.wait_for_file(f"/tmp/fortify.1000/tmpdir/{check_offset}/sandbox-ok", timeout=15)
+
+
+check_sandbox("preset")
+check_sandbox("tty")
+check_sandbox("mapuid")
+
+# Exit Sway and verify process exit status 0:
+swaymsg("exit", succeed=False)
+machine.wait_for_file("/tmp/sway-exit-ok")
+
+# Print fortify runDir contents:
+print(machine.succeed("find /run/user/1000/fortify"))

test/sandbox/tool/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"git.gensokyo.uk/security/fortify/test/sandbox"
+)
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("test: ")
+
+	if len(os.Args) < 2 {
+		log.Fatal("invalid argument")
+	}
+
+	switch os.Args[1] {
+	case "filter":
+		if len(os.Args) != 4 {
+			log.Fatal("invalid argument")
+		}
+
+		if pid, err := strconv.Atoi(strings.TrimSpace(os.Args[2])); err != nil {
+			log.Fatalf("%s", err)
+		} else if pid < 1 {
+			log.Fatalf("%d out of range", pid)
+		} else {
+			sandbox.MustCheckFilter(pid, os.Args[3])
+			return
+		}
+
+	default:
+		(&sandbox.T{FS: os.DirFS("/")}).MustCheckFile(os.Args[1], "/tmp/sandbox-ok")
+		return
+	}
+}

test/sandbox/tool/package.nix

@@ -0,0 +1,30 @@
+{
+  lib,
+  buildGoModule,
+  pkg-config,
+  util-linux,
+
+  version,
+}:
+buildGoModule rec {
+  pname = "check-sandbox";
+  inherit version;
+
+  src = builtins.path {
+    name = "${pname}-src";
+    path = lib.cleanSource ../.;
+    filter = path: type: (type == "directory") || (type == "regular" && lib.hasSuffix ".go" path);
+  };
+  vendorHash = null;
+
+  buildInputs = [ util-linux ];
+  nativeBuildInputs = [ pkg-config ];
+
+  preBuild = ''
+    go mod init git.gensokyo.uk/security/fortify/test/sandbox >& /dev/null
+  '';
+
+  postInstall = ''
+    mv $out/bin/tool $out/bin/fortify-test
+  '';
+}

test/test.py

@@ -99,34 +99,15 @@ print(denyOutputVerbose)
 # Fail direct fsu call:
 print(machine.fail("sudo -u alice -i fsu"))
 
-# Verify capabilities/securebits in user namespace:
-print(machine.succeed("sudo -u alice -i fortify run capsh --print"))
-print(machine.succeed("sudo -u alice -i fortify run capsh --has-no-new-privs"))
-print(machine.fail("sudo -u alice -i fortify run capsh --has-a=CAP_SYS_ADMIN"))
-print(machine.fail("sudo -u alice -i fortify run capsh --has-b=CAP_SYS_ADMIN"))
-print(machine.fail("sudo -u alice -i fortify run capsh --has-i=CAP_SYS_ADMIN"))
-print(machine.fail("sudo -u alice -i fortify run capsh --has-p=CAP_SYS_ADMIN"))
-print(machine.fail("sudo -u alice -i fortify run umount -R /dev"))
-
 # Verify PrintBaseError behaviour:
 if denyOutput != "fsu: uid 1001 is not in the fsurc file\n":
     raise Exception(f"unexpected deny output:\n{denyOutput}")
 if denyOutputVerbose != "fsu: uid 1001 is not in the fsurc file\nfortify: *cannot obtain uid from fsu: permission denied\n":
     raise Exception(f"unexpected deny verbose output:\n{denyOutputVerbose}")
 
-# Check sandbox outcome:
 check_offset = 0
-def check_sandbox(name):
-    global check_offset
-    check_offset += 1
-    swaymsg(f"exec script /dev/null -E always -qec check-sandbox-{name}")
-    machine.wait_for_file(f"/tmp/fortify.1000/tmpdir/{check_offset}/sandbox-ok", timeout=15)
 
 
-check_sandbox("preset")
-check_sandbox("tty")
-check_sandbox("mapuid")
-
 def aid(offset):
     return 1+check_offset+offset
 
@@ -195,25 +176,11 @@ machine.send_chars("clear; wayland-info && touch /tmp/client-ok\n")
 machine.wait_for_file(tmpdir_path(0, "client-ok"), timeout=15)
 collect_state_ui("foot_wayland")
 check_state("ne-foot", 1)
-# Verify acl on XDG_RUNTIME_DIR:
-print(machine.succeed(f"getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep {aid(0) + 1000000}"))
+# Verify lack of acl on XDG_RUNTIME_DIR:
+machine.fail(f"getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep {aid(0) + 1000000}")
 machine.send_chars("exit\n")
 machine.wait_until_fails("pgrep foot", timeout=5)
-# Verify acl cleanup on XDG_RUNTIME_DIR:
-machine.wait_until_fails(f"getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep {aid(0) + 1000000}", timeout=5)
-
-# Start app (foot) with Wayland enablement from a terminal:
-swaymsg("exec foot $SHELL -c '(ne-foot) & sleep 1 && fortify show $(fortify ps --short) && touch /tmp/ps-show-ok && cat'")
-wait_for_window(f"u0_a{aid(0)}@machine")
-machine.send_chars("clear; wayland-info && touch /tmp/term-ok\n")
-machine.wait_for_file(tmpdir_path(0, "term-ok"), timeout=15)
-machine.wait_for_file("/tmp/ps-show-ok", timeout=5)
-collect_state_ui("foot_wayland_term")
-check_state("ne-foot", 1)
-machine.send_chars("exit\n")
-wait_for_window("foot")
-machine.send_key("ctrl-c")
-machine.wait_until_fails("pgrep foot", timeout=5)
+machine.fail(f"getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep {aid(0) + 1000000}", timeout=5)
 
 # Test PulseAudio (fortify does not support PipeWire yet):
 swaymsg("exec pa-foot")
@@ -252,6 +219,22 @@ machine.wait_until_fails(f"getfacl --absolute-names --omit-header --numeric /run
 # Test syscall filter:
 print(machine.fail("sudo -u alice -i XDG_RUNTIME_DIR=/run/user/1000 strace-failure"))
 
+# Start app (foot) with Wayland enablement from a terminal:
+swaymsg("exec foot $SHELL -c '(ne-foot) & disown && exec $SHELL'")
+wait_for_window(f"u0_a{aid(0)}@machine")
+machine.send_chars("clear; wayland-info && touch /tmp/term-ok\n")
+machine.wait_for_file(tmpdir_path(0, "term-ok"), timeout=15)
+machine.send_key("alt-h")
+machine.send_chars("clear; fortify show $(fortify ps --short) && touch /tmp/ps-show-ok && exec cat\n")
+machine.wait_for_file("/tmp/ps-show-ok", timeout=5)
+collect_state_ui("foot_wayland_term")
+check_state("ne-foot", 1)
+machine.send_key("alt-l")
+machine.send_chars("exit\n")
+wait_for_window("alice@machine")
+machine.send_key("ctrl-c")
+machine.wait_until_fails("pgrep foot", timeout=5)
+
 # Exit Sway and verify process exit status 0:
 swaymsg("exit", succeed=False)
 machine.wait_for_file("/tmp/sway-exit-ok")