release: 0.3.3

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

.gitea/workflows/test.yml

@@ -5,25 +5,107 @@ on:
   - pull_request
 
 jobs:
-  test:
-    name: Run NixOS test
+  fortify:
+    name: Fortify
     runs-on: nix
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Run tests
-        run: |
-          nix --print-build-logs --experimental-features 'nix-command flakes' flake check
-          nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.nixos-tests
+      - name: Run NixOS test
+        run: nix build --out-link "result" --print-out-paths --print-build-logs .#checks.x86_64-linux.fortify
 
       - name: Upload test output
         uses: actions/upload-artifact@v3
         with:
-          name: "nixos-vm-output"
+          name: "fortify-vm-output"
           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
+    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.fpkg
+
+      - name: Upload test output
+        uses: actions/upload-artifact@v3
+        with:
+          name: "fpkg-vm-output"
+          path: result/*
+          retention-days: 1
+
+  check:
+    name: Flake checks
+    needs:
+      - fortify
+      - race
+      - sandbox
+      - sandbox-race
+      - fpkg
+    runs-on: nix
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run checks
+        run: nix --print-build-logs --experimental-features 'nix-command flakes' flake check
+
   dist:
     name: Create distribution
     runs-on: nix

acl/acl-update.c

@@ -0,0 +1,69 @@
+#include "acl-update.h"
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/acl.h>
+#include <acl/libacl.h>
+
+int f_acl_update_file_by_uid(const char *path_p, uid_t uid, acl_perm_t *perms, size_t plen) {
+    int ret = -1;
+    bool v;
+    int i;
+    acl_t acl;
+    acl_entry_t entry;
+    acl_tag_t tag_type;
+    void *qualifier_p;
+    acl_permset_t permset;
+
+    acl = acl_get_file(path_p, ACL_TYPE_ACCESS);
+    if (acl == NULL)
+        goto out;
+
+    // prune entries by uid
+    for (i = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry); i == 1; i = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry)) {
+        if (acl_get_tag_type(entry, &tag_type) != 0)
+            return -1;
+        if (tag_type != ACL_USER)
+            continue;
+
+        qualifier_p = acl_get_qualifier(entry);
+        if (qualifier_p == NULL)
+            return -1;
+        v = *(uid_t *)qualifier_p == uid;
+        acl_free(qualifier_p);
+
+        if (!v)
+            continue;
+
+        acl_delete_entry(acl, entry);
+    }
+
+    if (plen == 0)
+        goto set;
+
+    if (acl_create_entry(&acl, &entry) != 0)
+        goto out;
+    if (acl_get_permset(entry, &permset) != 0)
+        goto out;
+    for (i = 0; i < plen; i++) {
+        if (acl_add_perm(permset, perms[i]) != 0)
+            goto out;
+    }
+    if (acl_set_tag_type(entry, ACL_USER) != 0)
+        goto out;
+    if (acl_set_qualifier(entry, (void *)&uid) != 0)
+        goto out;
+
+set:
+    if (acl_calc_mask(&acl) != 0)
+        goto out;
+    if (acl_valid(acl) != 0)
+        goto out;
+    if (acl_set_file(path_p, ACL_TYPE_ACCESS, acl) == 0)
+        ret = 0;
+
+out:
+    free((void *)path_p);
+    if (acl != NULL)
+        acl_free((void *)acl);
+    return ret;
+}

acl/acl-update.h

@@ -0,0 +1,3 @@
+#include <sys/acl.h>
+
+int f_acl_update_file_by_uid(const char *path_p, uid_t uid, acl_perm_t *perms, size_t plen);

acl/acl.go

@@ -1,19 +1,36 @@
 // Package acl implements simple ACL manipulation via libacl.
 package acl
 
-type Perms []Perm
+/*
+#cgo linux pkg-config: --static libacl
 
-func (ps Perms) String() string {
-	var s = []byte("---")
-	for _, p := range ps {
-		switch p {
-		case Read:
-			s[0] = 'r'
-		case Write:
-			s[1] = 'w'
-		case Execute:
-			s[2] = 'x'
-		}
+#include "acl-update.h"
+*/
+import "C"
+
+type Perm C.acl_perm_t
+
+const (
+	Read    Perm = C.ACL_READ
+	Write   Perm = C.ACL_WRITE
+	Execute Perm = C.ACL_EXECUTE
+)
+
+// Update replaces ACL_USER entry with qualifier uid.
+func Update(name string, uid int, perms ...Perm) error {
+	var p *Perm
+	if len(perms) > 0 {
+		p = &perms[0]
 	}
-	return string(s)
+
+	r, err := C.f_acl_update_file_by_uid(
+		C.CString(name),
+		C.uid_t(uid),
+		(*C.acl_perm_t)(p),
+		C.size_t(len(perms)),
+	)
+	if r == 0 {
+		return nil
+	}
+	return err
 }

acl/acl_test.go

@@ -47,7 +47,7 @@ func TestUpdatePerm(t *testing.T) {
 	})
 
 	t.Run("default clear mask", func(t *testing.T) {
-		if err := acl.UpdatePerm(testFilePath, uid); err != nil {
+		if err := acl.Update(testFilePath, uid); err != nil {
 			t.Fatalf("UpdatePerm: error = %v", err)
 		}
 		if cur = getfacl(t, testFilePath); len(cur) != 4 {
@@ -56,7 +56,7 @@ func TestUpdatePerm(t *testing.T) {
 	})
 
 	t.Run("default clear consistency", func(t *testing.T) {
-		if err := acl.UpdatePerm(testFilePath, uid); err != nil {
+		if err := acl.Update(testFilePath, uid); err != nil {
 			t.Fatalf("UpdatePerm: error = %v", err)
 		}
 		if val := getfacl(t, testFilePath); !reflect.DeepEqual(val, cur) {
@@ -76,7 +76,7 @@ func TestUpdatePerm(t *testing.T) {
 func testUpdate(t *testing.T, testFilePath, name string, cur []*getFAclResp, val fAclPerm, perms ...acl.Perm) {
 	t.Run(name, func(t *testing.T) {
 		t.Cleanup(func() {
-			if err := acl.UpdatePerm(testFilePath, uid); err != nil {
+			if err := acl.Update(testFilePath, uid); err != nil {
 				t.Fatalf("UpdatePerm: error = %v", err)
 			}
 			if v := getfacl(t, testFilePath); !reflect.DeepEqual(v, cur) {
@@ -84,7 +84,7 @@ func testUpdate(t *testing.T, testFilePath, name string, cur []*getFAclResp, val
 			}
 		})
 
-		if err := acl.UpdatePerm(testFilePath, uid, perms...); err != nil {
+		if err := acl.Update(testFilePath, uid, perms...); err != nil {
 			t.Fatalf("UpdatePerm: error = %v", err)
 		}
 		r := respByCred(getfacl(t, testFilePath), fAclTypeUser, cred)

acl/c.go

@@ -1,196 +0,0 @@
-package acl
-
-import "C"
-import (
-	"errors"
-	"runtime"
-	"syscall"
-	"unsafe"
-)
-
-/*
-#cgo linux pkg-config: --static libacl
-
-#include <stdlib.h>
-#include <sys/acl.h>
-#include <acl/libacl.h>
-
-static acl_t _go_acl_get_file(const char *path_p, acl_type_t type) {
-	acl_t acl = acl_get_file(path_p, type);
-	free((void *)path_p);
-	return acl;
-}
-
-static int _go_acl_set_file(const char *path_p, acl_type_t type, acl_t acl) {
-	if (acl_valid(acl) != 0) {
-		return -1;
-	}
-
-	int ret = acl_set_file(path_p, type, acl);
-	free((void *)path_p);
-	return ret;
-}
-*/
-import "C"
-
-func getFile(name string, t C.acl_type_t) (*ACL, error) {
-	a, err := C._go_acl_get_file(C.CString(name), t)
-	if errors.Is(err, syscall.ENODATA) {
-		err = nil
-	}
-
-	return newACL(a), err
-}
-
-func (acl *ACL) setFile(name string, t C.acl_type_t) error {
-	_, err := C._go_acl_set_file(C.CString(name), t, acl.acl)
-	return err
-}
-
-func newACL(a C.acl_t) *ACL {
-	acl := &ACL{a}
-	runtime.SetFinalizer(acl, (*ACL).free)
-	return acl
-}
-
-type ACL struct {
-	acl C.acl_t
-}
-
-func (acl *ACL) free() {
-	C.acl_free(unsafe.Pointer(acl.acl))
-
-	// no need for a finalizer anymore
-	runtime.SetFinalizer(acl, nil)
-}
-
-const (
-	Read    = C.ACL_READ
-	Write   = C.ACL_WRITE
-	Execute = C.ACL_EXECUTE
-
-	TypeDefault = C.ACL_TYPE_DEFAULT
-	TypeAccess  = C.ACL_TYPE_ACCESS
-
-	UndefinedTag = C.ACL_UNDEFINED_TAG
-	UserObj      = C.ACL_USER_OBJ
-	User         = C.ACL_USER
-	GroupObj     = C.ACL_GROUP_OBJ
-	Group        = C.ACL_GROUP
-	Mask         = C.ACL_MASK
-	Other        = C.ACL_OTHER
-)
-
-type (
-	Perm C.acl_perm_t
-)
-
-func (acl *ACL) removeEntry(tt C.acl_tag_t, tq int) error {
-	var e C.acl_entry_t
-
-	// get first entry
-	if r, err := C.acl_get_entry(acl.acl, C.ACL_FIRST_ENTRY, &e); err != nil {
-		return err
-	} else if r == 0 {
-		// return on acl with no entries
-		return nil
-	}
-
-	for {
-		if r, err := C.acl_get_entry(acl.acl, C.ACL_NEXT_ENTRY, &e); err != nil {
-			return err
-		} else if r == 0 {
-			// return on drained acl
-			return nil
-		}
-
-		var (
-			q int
-			t C.acl_tag_t
-		)
-
-		// get current entry tag type
-		if _, err := C.acl_get_tag_type(e, &t); err != nil {
-			return err
-		}
-
-		// get current entry qualifier
-		if rq, err := C.acl_get_qualifier(e); err != nil {
-			// neither ACL_USER nor ACL_GROUP
-			if errors.Is(err, syscall.EINVAL) {
-				continue
-			}
-
-			return err
-		} else {
-			q = *(*int)(rq)
-			C.acl_free(rq)
-		}
-
-		// delete on match
-		if t == tt && q == tq {
-			_, err := C.acl_delete_entry(acl.acl, e)
-			return err
-		}
-	}
-}
-
-func UpdatePerm(name string, uid int, perms ...Perm) error {
-	// read acl from file
-	a, err := getFile(name, TypeAccess)
-	if err != nil {
-		return err
-	}
-	// free acl on return if get is successful
-	defer a.free()
-
-	// remove existing entry
-	if err = a.removeEntry(User, uid); err != nil {
-		return err
-	}
-
-	// create new entry if perms are passed
-	if len(perms) > 0 {
-		// create new acl entry
-		var e C.acl_entry_t
-		if _, err = C.acl_create_entry(&a.acl, &e); err != nil {
-			return err
-		}
-
-		// get perm set of new entry
-		var p C.acl_permset_t
-		if _, err = C.acl_get_permset(e, &p); err != nil {
-			return err
-		}
-
-		// add target perms
-		for _, perm := range perms {
-			if _, err = C.acl_add_perm(p, C.acl_perm_t(perm)); err != nil {
-				return err
-			}
-		}
-
-		// set perm set to new entry
-		if _, err = C.acl_set_permset(e, p); err != nil {
-			return err
-		}
-
-		// set user tag to new entry
-		if _, err = C.acl_set_tag_type(e, User); err != nil {
-			return err
-		}
-
-		// set qualifier (uid) to new entry
-		if _, err = C.acl_set_qualifier(e, unsafe.Pointer(&uid)); err != nil {
-			return err
-		}
-	}
-
-	// calculate mask after update
-	if _, err = C.acl_calc_mask(&a.acl); err != nil {
-		return err
-	}
-
-	// write acl to file
-	return a.setFile(name, TypeAccess)
-}

acl/perms.go

@@ -0,0 +1,18 @@
+package acl
+
+type Perms []Perm
+
+func (ps Perms) String() string {
+	var s = []byte("---")
+	for _, p := range ps {
+		switch p {
+		case Read:
+			s[0] = 'r'
+		case Write:
+			s[1] = 'w'
+		case Execute:
+			s[2] = 'x'
+		}
+	}
+	return string(s)
+}

cmd/fpkg/app.go

@@ -0,0 +1,150 @@
+package main
+
+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 appInfo struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+
+	// passed through to [fst.Config]
+	ID string `json:"id"`
+	// passed through to [fst.Config]
+	AppID int `json:"app_id"`
+	// passed through to [fst.Config]
+	Groups []string `json:"groups,omitempty"`
+	// passed through to [fst.Config]
+	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]
+	Tty bool `json:"tty,omitempty"`
+	// passed through to [fst.Config]
+	MapRealUID bool `json:"map_real_uid,omitempty"`
+	// passed through to [fst.Config]
+	DirectWayland bool `json:"direct_wayland,omitempty"`
+	// passed through to [fst.Config]
+	SystemBus *dbus.Config `json:"system_bus,omitempty"`
+	// passed through to [fst.Config]
+	SessionBus *dbus.Config `json:"session_bus,omitempty"`
+	// passed through to [fst.Config]
+	Enablements system.Enablement `json:"enablements"`
+
+	// passed through to [fst.Config]
+	Multiarch bool `json:"multiarch,omitempty"`
+	// passed through to [fst.Config]
+	Bluetooth bool `json:"bluetooth,omitempty"`
+
+	// allow gpu access within sandbox
+	GPU bool `json:"gpu"`
+	// store path to nixGL mesa wrappers
+	Mesa string `json:"mesa,omitempty"`
+	// store path to nixGL source
+	NixGL string `json:"nix_gl,omitempty"`
+	// store path to activate-and-exec script
+	Launcher string `json:"launcher"`
+	// store path to /run/current-system
+	CurrentSystem string `json:"current_system"`
+	// store path to home-manager activation package
+	ActivationPackage string `json:"activation_package"`
+}
+
+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,
+			Shell:    shellPath,
+			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)
+	} else if err = json.NewDecoder(f).Decode(&bundle); err != nil {
+		beforeFail()
+		log.Fatalf("cannot parse bundle metadata: %v", err)
+	} else if err = f.Close(); err != nil {
+		log.Printf("cannot close bundle metadata: %v", err)
+		// not fatal
+	}
+
+	if bundle.ID == "" {
+		beforeFail()
+		log.Fatal("application identifier must not be empty")
+	}
+
+	return bundle
+}
+
+func formatHostname(name string) string {
+	if h, err := os.Hostname(); err != nil {
+		log.Printf("cannot get hostname: %v", err)
+		return "fortify-" + name
+	} else {
+		return h + "-" + name
+	}
+}

cmd/fpkg/build.nix

@@ -7,6 +7,8 @@
 
 {
   lib,
+  stdenv,
+  closureInfo,
   writeScript,
   runtimeShell,
   writeText,
@@ -15,12 +17,15 @@
   runCommand,
   fetchFromGitHub,
 
+  zstd,
   nix,
+  sqlite,
 
   name ? throw "name is required",
   version ? throw "version is required",
   pname ? "${name}-${version}",
   modules ? [ ],
+  nixosModules ? [ ],
   script ? ''
     exec "$SHELL" "$@"
   '',
@@ -72,6 +77,8 @@ let
         etc.nixpkgs.source = nixpkgs.outPath;
         systemPackages = [ pkgs.nix ];
       };
+
+      imports = nixosModules;
     };
   nixos = nixpkgs.lib.nixosSystem {
     inherit system;
@@ -164,11 +171,7 @@ let
           broadcast = { };
         });
 
-    enablements =
-      (if allow_wayland then 1 else 0)
-      + (if allow_x11 then 2 else 0)
-      + (if allow_dbus then 4 else 0)
-      + (if allow_pulse then 8 else 0);
+    enablements = (if allow_wayland then 1 else 0) + (if allow_x11 then 2 else 0) + (if allow_dbus then 4 else 0) + (if allow_pulse then 8 else 0);
 
     mesa = if gpu then mesaWrappers else null;
     nix_gl = if gpu then nixGL else null;
@@ -177,26 +180,73 @@ let
   };
 in
 
-writeScript "fortify-${pname}-bundle-prelude" ''
-  #!${runtimeShell} -el
-  OUT="$(mktemp -d)"
-  TAR="$(mktemp -u)"
-  set -x
+stdenv.mkDerivation {
+  name = "${pname}.pkg";
+  inherit version;
+  __structuredAttrs = true;
 
-  nix copy --no-check-sigs --to "$OUT" "${nix}" "${nixos.config.system.build.toplevel}"
-  nix store --store "$OUT" optimise
-  chmod -R +r "$OUT/nix/var"
-  nix copy --no-check-sigs --to "file://$OUT/res?compression=zstd&compression-level=19&parallel-compression=true" \
-    "${homeManagerConfiguration.activationPackage}" \
-    "${launcher}" ${if gpu then "${mesaWrappers} ${nixGL}" else ""}
-  mkdir -p "$OUT/etc"
-  tar -C "$OUT/etc" -xf "${etc}/etc.tar"
-  cp "${writeText "bundle.json" info}" "$OUT/bundle.json"
+  nativeBuildInputs = [
+    zstd
+    nix
+    sqlite
+  ];
 
-  # creating an intermediate file improves zstd performance
-  tar -C "$OUT" -cf "$TAR" .
-  chmod +w -R "$OUT" && rm -rf "$OUT"
+  buildCommand = ''
+    NIX_ROOT="$(mktemp -d)"
+    export USER="nobody"
 
-  zstd -T0 -19 -fo "${pname}.pkg" "$TAR"
-  rm "$TAR"
-''
+    # create bootstrap store
+    bootstrapClosureInfo="${
+      closureInfo {
+        rootPaths = [
+          nix
+          nixos.config.system.build.toplevel
+        ];
+      }
+    }"
+    echo "copying bootstrap store paths..."
+    mkdir -p "$NIX_ROOT/nix/store"
+    xargs -n 1 -a "$bootstrapClosureInfo/store-paths" cp -at "$NIX_ROOT/nix/store/"
+    NIX_REMOTE="local?root=$NIX_ROOT" nix-store --load-db < "$bootstrapClosureInfo/registration"
+    NIX_REMOTE="local?root=$NIX_ROOT" nix-store --optimise
+    sqlite3 "$NIX_ROOT/nix/var/nix/db/db.sqlite" "UPDATE ValidPaths SET registrationTime = ''${SOURCE_DATE_EPOCH}"
+    chmod -R +r "$NIX_ROOT/nix/var"
+
+    # create binary cache
+    closureInfo="${
+      closureInfo {
+        rootPaths =
+          [
+            homeManagerConfiguration.activationPackage
+            launcher
+          ]
+          ++ optionals gpu [
+            mesaWrappers
+            nixGL
+          ];
+      }
+    }"
+    echo "copying application paths..."
+    TMP_STORE="$(mktemp -d)"
+    mkdir -p "$TMP_STORE/nix/store"
+    xargs -n 1 -a "$closureInfo/store-paths" cp -at "$TMP_STORE/nix/store/"
+    NIX_REMOTE="local?root=$TMP_STORE" nix-store --load-db < "$closureInfo/registration"
+    sqlite3 "$TMP_STORE/nix/var/nix/db/db.sqlite" "UPDATE ValidPaths SET registrationTime = ''${SOURCE_DATE_EPOCH}"
+    NIX_REMOTE="local?root=$TMP_STORE" nix --offline --extra-experimental-features nix-command \
+        --verbose --log-format raw-with-logs \
+        copy --all --no-check-sigs --to \
+        "file://$NIX_ROOT/res?compression=zstd&compression-level=19&parallel-compression=true"
+
+    # package /etc
+    mkdir -p "$NIX_ROOT/etc"
+    tar -C "$NIX_ROOT/etc" -xf "${etc}/etc.tar"
+
+    # write metadata
+    cp "${writeText "bundle.json" info}" "$NIX_ROOT/bundle.json"
+
+    # create an intermediate file to improve zstd performance
+    INTER="$(mktemp)"
+    tar -C "$NIX_ROOT" -cf "$INTER" .
+    zstd -T0 -19 -fo "$out" "$INTER"
+  '';
+}

cmd/fpkg/bundle.go

@@ -1,90 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"os"
-
-	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/system"
-)
-
-type bundleInfo struct {
-	Name    string `json:"name"`
-	Version string `json:"version"`
-
-	// passed through to [fst.Config]
-	ID string `json:"id"`
-	// passed through to [fst.Config]
-	AppID int `json:"app_id"`
-	// passed through to [fst.Config]
-	Groups []string `json:"groups,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"`
-	// passed through to [fst.Config]
-	MapRealUID bool `json:"map_real_uid,omitempty"`
-	// passed through to [fst.Config]
-	DirectWayland bool `json:"direct_wayland,omitempty"`
-	// passed through to [fst.Config]
-	SystemBus *dbus.Config `json:"system_bus,omitempty"`
-	// passed through to [fst.Config]
-	SessionBus *dbus.Config `json:"session_bus,omitempty"`
-	// passed through to [fst.Config]
-	Enablements system.Enablements `json:"enablements"`
-
-	// passed through inverted to [bwrap.SyscallPolicy]
-	Devel bool `json:"devel,omitempty"`
-	// passed through to [bwrap.SyscallPolicy]
-	Multiarch bool `json:"multiarch,omitempty"`
-	// passed through to [bwrap.SyscallPolicy]
-	Bluetooth bool `json:"bluetooth,omitempty"`
-
-	// allow gpu access within sandbox
-	GPU bool `json:"gpu"`
-	// store path to nixGL mesa wrappers
-	Mesa string `json:"mesa,omitempty"`
-	// store path to nixGL source
-	NixGL string `json:"nix_gl,omitempty"`
-	// store path to activate-and-exec script
-	Launcher string `json:"launcher"`
-	// store path to /run/current-system
-	CurrentSystem string `json:"current_system"`
-	// store path to home-manager activation package
-	ActivationPackage string `json:"activation_package"`
-}
-
-func loadBundleInfo(name string, beforeFail func()) *bundleInfo {
-	bundle := new(bundleInfo)
-	if f, err := os.Open(name); err != nil {
-		beforeFail()
-		fmsg.Fatalf("cannot open bundle: %v", err)
-	} else if err = json.NewDecoder(f).Decode(&bundle); err != nil {
-		beforeFail()
-		fmsg.Fatalf("cannot parse bundle metadata: %v", err)
-	} else if err = f.Close(); err != nil {
-		fmsg.Printf("cannot close bundle metadata: %v", err)
-		// not fatal
-	}
-
-	if bundle.ID == "" {
-		beforeFail()
-		fmsg.Fatal("application identifier must not be empty")
-	}
-
-	return bundle
-}
-
-func formatHostname(name string) string {
-	if h, err := os.Hostname(); err != nil {
-		fmsg.Printf("cannot get hostname: %v", err)
-		return "fortify-" + name
-	} else {
-		return h + "-" + name
-	}
-}

cmd/fpkg/install.go

@@ -1,195 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"flag"
-	"os"
-	"path"
-
-	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-func actionInstall(args []string) {
-	set := flag.NewFlagSet("install", flag.ExitOnError)
-	var (
-		dropShellInstall  bool
-		dropShellActivate bool
-	)
-	set.BoolVar(&dropShellInstall, "si", false, "Drop to a shell on installation")
-	set.BoolVar(&dropShellActivate, "sa", false, "Drop to a shell on activation")
-
-	// Ignore errors; set is set for ExitOnError.
-	_ = set.Parse(args)
-
-	args = set.Args()
-
-	if len(args) != 1 {
-		fmsg.Fatal("invalid argument")
-	}
-	pkgPath := args[0]
-	if !path.IsAbs(pkgPath) {
-		if dir, err := os.Getwd(); err != nil {
-			fmsg.Fatalf("cannot get current directory: %v", err)
-		} else {
-			pkgPath = path.Join(dir, pkgPath)
-		}
-	}
-
-	/*
-		Look up paths to programs started by fpkg.
-		This is done here to ease error handling as cleanup is not yet required.
-	*/
-
-	var (
-		_     = lookPath("zstd")
-		tar   = lookPath("tar")
-		chmod = lookPath("chmod")
-		rm    = lookPath("rm")
-	)
-
-	/*
-		Extract package and set up for cleanup.
-	*/
-
-	var workDir string
-	if p, err := os.MkdirTemp("", "fpkg.*"); err != nil {
-		fmsg.Fatalf("cannot create temporary directory: %v", err)
-	} else {
-		workDir = p
-	}
-	cleanup := func() {
-		// should be faster than a native implementation
-		mustRun(chmod, "-R", "+w", workDir)
-		mustRun(rm, "-rf", workDir)
-	}
-	beforeRunFail.Store(&cleanup)
-
-	mustRun(tar, "-C", workDir, "-xf", pkgPath)
-
-	/*
-		Parse bundle and app metadata, do pre-install checks.
-	*/
-
-	bundle := loadBundleInfo(path.Join(workDir, "bundle.json"), cleanup)
-	pathSet := pathSetByApp(bundle.ID)
-
-	app := bundle
-	if s, err := os.Stat(pathSet.metaPath); err != nil {
-		if !os.IsNotExist(err) {
-			cleanup()
-			fmsg.Fatalf("cannot access %q: %v", pathSet.metaPath, err)
-			panic("unreachable")
-		}
-		// did not modify app, clean installation condition met later
-	} else if s.IsDir() {
-		cleanup()
-		fmsg.Fatalf("metadata path %q is not a file", pathSet.metaPath)
-		panic("unreachable")
-	} else {
-		app = loadBundleInfo(pathSet.metaPath, cleanup)
-		if app.ID != bundle.ID {
-			cleanup()
-			fmsg.Fatalf("app %q claims to have identifier %q", bundle.ID, app.ID)
-		}
-		// sec: should verify credentials
-	}
-
-	if app != bundle {
-		// do not try to re-install
-		if app.NixGL == bundle.NixGL &&
-			app.CurrentSystem == bundle.CurrentSystem &&
-			app.Launcher == bundle.Launcher &&
-			app.ActivationPackage == bundle.ActivationPackage {
-			cleanup()
-			fmsg.Printf("package %q is identical to local application %q", pkgPath, app.ID)
-			fmsg.Exit(0)
-		}
-
-		// AppID determines uid
-		if app.AppID != bundle.AppID {
-			cleanup()
-			fmsg.Fatalf("package %q app id %d differs from installed %d", pkgPath, bundle.AppID, app.AppID)
-			panic("unreachable")
-		}
-
-		// sec: should compare version string
-		fmsg.VPrintf("installing application %q version %q over local %q", bundle.ID, bundle.Version, app.Version)
-	} else {
-		fmsg.VPrintf("application %q clean installation", bundle.ID)
-		// sec: should install credentials
-	}
-
-	/*
-		Setup steps for files owned by the target user.
-	*/
-
-	withCacheDir("install", []string{
-		// export inner bundle path in the environment
-		"export BUNDLE=" + fst.Tmp + "/bundle",
-		// replace inner /etc
-		"mkdir -p etc",
-		"chmod -R +w etc",
-		"rm -rf etc",
-		"cp -dRf $BUNDLE/etc etc",
-		// replace inner /nix
-		"mkdir -p nix",
-		"chmod -R +w nix",
-		"rm -rf nix",
-		"cp -dRf /nix nix",
-		// copy from binary cache
-		"nix copy --offline --no-check-sigs --all --from file://$BUNDLE/res --to $PWD",
-		// deduplicate nix store
-		"nix store --offline --store $PWD optimise",
-		// make cache directory world-readable for autoetc
-		"chmod 0755 .",
-	}, workDir, bundle, pathSet, dropShellInstall, cleanup)
-
-	if bundle.GPU {
-		withCacheDir("mesa-wrappers", []string{
-			// link nixGL mesa wrappers
-			"mkdir -p nix/.nixGL",
-			"ln -s " + bundle.Mesa + "/bin/nixGLIntel nix/.nixGL/nixGL",
-			"ln -s " + bundle.Mesa + "/bin/nixVulkanIntel nix/.nixGL/nixVulkan",
-		}, workDir, bundle, pathSet, false, cleanup)
-	}
-
-	/*
-		Activate home-manager generation.
-	*/
-
-	withNixDaemon("activate", []string{
-		// clean up broken links
-		"mkdir -p .local/state/{nix,home-manager}",
-		"chmod -R +w .local/state/{nix,home-manager}",
-		"rm -rf .local/state/{nix,home-manager}",
-		// run activation script
-		bundle.ActivationPackage + "/activate",
-	}, false, func(config *fst.Config) *fst.Config { return config }, bundle, pathSet, dropShellActivate, cleanup)
-
-	/*
-		Installation complete. Write metadata to block re-installs or downgrades.
-	*/
-
-	// serialise metadata to ensure consistency
-	if f, err := os.OpenFile(pathSet.metaPath+"~", os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644); err != nil {
-		cleanup()
-		fmsg.Fatalf("cannot create metadata file: %v", err)
-		panic("unreachable")
-	} else if err = json.NewEncoder(f).Encode(bundle); err != nil {
-		cleanup()
-		fmsg.Fatalf("cannot write metadata: %v", err)
-		panic("unreachable")
-	} else if err = f.Close(); err != nil {
-		fmsg.Printf("cannot close metadata file: %v", err)
-		// not fatal
-	}
-
-	if err := os.Rename(pathSet.metaPath+"~", pathSet.metaPath); err != nil {
-		cleanup()
-		fmsg.Fatalf("cannot rename metadata file: %v", err)
-		panic("unreachable")
-	}
-
-	cleanup()
-}

cmd/fpkg/main.go

@@ -1,48 +1,351 @@
 package main
 
 import (
-	"flag"
+	"context"
+	"encoding/json"
+	"errors"
+	"log"
 	"os"
+	"os/signal"
+	"path"
+	"syscall"
 
+	"git.gensokyo.uk/security/fortify/command"
+	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal"
+	"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 shell = "/run/current-system/sw/bin/bash"
-
-func init() {
-	if err := os.Setenv("SHELL", shell); err != nil {
-		fmsg.Fatalf("cannot set $SHELL: %v", err)
-	}
-}
+const shellPath = "/run/current-system/sw/bin/bash"
 
 var (
-	flagVerbose bool
+	errSuccess = errors.New("success")
+
+	std sys.State = new(sys.Std)
 )
 
 func init() {
-	flag.BoolVar(&flagVerbose, "v", false, "Verbose output")
+	fmsg.Prepare("fpkg")
+	if err := os.Setenv("SHELL", shellPath); err != nil {
+		log.Fatalf("cannot set $SHELL: %v", err)
+	}
 }
 
 func main() {
-	fmsg.SetPrefix("fpkg")
+	// early init path, skips root check and duplicate PR_SET_DUMPABLE
+	sandbox.TryArgv0(fmsg.Output{}, fmsg.Prepare, internal.InstallFmsg)
 
-	flag.Parse()
-	fmsg.SetVerbose(flagVerbose)
-
-	args := flag.Args()
-	if len(args) < 1 {
-		fmsg.Fatal("invalid argument")
+	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
 	}
 
-	switch args[0] {
-	case "install":
-		actionInstall(args[1:])
-	case "start":
-		actionStart(args[1:])
-
-	default:
-		fmsg.Fatal("invalid argument")
+	if os.Geteuid() == 0 {
+		log.Fatal("this program must not run as root")
 	}
 
-	fmsg.Exit(0)
+	ctx, stop := signal.NotifyContext(context.Background(),
+		syscall.SIGINT, syscall.SIGTERM)
+	defer stop() // unreachable
+
+	var (
+		flagVerbose   bool
+		flagDropShell bool
+	)
+	c := command.New(os.Stderr, log.Printf, "fpkg", func([]string) error {
+		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")
+
+	c.Command("shim", command.UsageInternal, func([]string) error { app.ShimMain(); return errSuccess })
+
+	{
+		var (
+			flagDropShellActivate bool
+		)
+		c.NewCommand("install", "Install an application from its package", func(args []string) error {
+			if len(args) != 1 {
+				log.Println("invalid argument")
+				return syscall.EINVAL
+			}
+			pkgPath := args[0]
+			if !path.IsAbs(pkgPath) {
+				if dir, err := os.Getwd(); err != nil {
+					log.Printf("cannot get current directory: %v", err)
+					return err
+				} else {
+					pkgPath = path.Join(dir, pkgPath)
+				}
+			}
+
+			/*
+				Look up paths to programs started by fpkg.
+				This is done here to ease error handling as cleanup is not yet required.
+			*/
+
+			var (
+				_     = lookPath("zstd")
+				tar   = lookPath("tar")
+				chmod = lookPath("chmod")
+				rm    = lookPath("rm")
+			)
+
+			/*
+				Extract package and set up for cleanup.
+			*/
+
+			var workDir string
+			if p, err := os.MkdirTemp("", "fpkg.*"); err != nil {
+				log.Printf("cannot create temporary directory: %v", err)
+				return err
+			} else {
+				workDir = p
+			}
+			cleanup := func() {
+				// should be faster than a native implementation
+				mustRun(chmod, "-R", "+w", workDir)
+				mustRun(rm, "-rf", workDir)
+			}
+			beforeRunFail.Store(&cleanup)
+
+			mustRun(tar, "-C", workDir, "-xf", pkgPath)
+
+			/*
+				Parse bundle and app metadata, do pre-install checks.
+			*/
+
+			bundle := loadAppInfo(path.Join(workDir, "bundle.json"), cleanup)
+			pathSet := pathSetByApp(bundle.ID)
+
+			a := bundle
+			if s, err := os.Stat(pathSet.metaPath); err != nil {
+				if !os.IsNotExist(err) {
+					cleanup()
+					log.Printf("cannot access %q: %v", pathSet.metaPath, err)
+					return err
+				}
+				// did not modify app, clean installation condition met later
+			} else if s.IsDir() {
+				cleanup()
+				log.Printf("metadata path %q is not a file", pathSet.metaPath)
+				return syscall.EBADMSG
+			} else {
+				a = loadAppInfo(pathSet.metaPath, cleanup)
+				if a.ID != bundle.ID {
+					cleanup()
+					log.Printf("app %q claims to have identifier %q",
+						bundle.ID, a.ID)
+					return syscall.EBADE
+				}
+				// sec: should verify credentials
+			}
+
+			if a != bundle {
+				// do not try to re-install
+				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, a.ID)
+					return errSuccess
+				}
+
+				// AppID determines uid
+				if a.AppID != bundle.AppID {
+					cleanup()
+					log.Printf("package %q app id %d differs from installed %d",
+						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, a.Version)
+			} else {
+				fmsg.Verbosef("application %q clean installation", bundle.ID)
+				// sec: should install credentials
+			}
+
+			/*
+				Setup steps for files owned by the target user.
+			*/
+
+			withCacheDir(ctx, "install", []string{
+				// export inner bundle path in the environment
+				"export BUNDLE=" + fst.Tmp + "/bundle",
+				// replace inner /etc
+				"mkdir -p etc",
+				"chmod -R +w etc",
+				"rm -rf etc",
+				"cp -dRf $BUNDLE/etc etc",
+				// replace inner /nix
+				"mkdir -p nix",
+				"chmod -R +w nix",
+				"rm -rf nix",
+				"cp -dRf /nix nix",
+				// copy from binary cache
+				"nix copy --offline --no-check-sigs --all --from file://$BUNDLE/res --to $PWD",
+				// deduplicate nix store
+				"nix store --offline --store $PWD optimise",
+				// make cache directory world-readable for autoetc
+				"chmod 0755 .",
+			}, workDir, bundle, pathSet, flagDropShell, cleanup)
+
+			if bundle.GPU {
+				withCacheDir(ctx, "mesa-wrappers", []string{
+					// link nixGL mesa wrappers
+					"mkdir -p nix/.nixGL",
+					"ln -s " + bundle.Mesa + "/bin/nixGLIntel nix/.nixGL/nixGL",
+					"ln -s " + bundle.Mesa + "/bin/nixVulkanIntel nix/.nixGL/nixVulkan",
+				}, workDir, bundle, pathSet, false, cleanup)
+			}
+
+			/*
+				Activate home-manager generation.
+			*/
+
+			withNixDaemon(ctx, "activate", []string{
+				// clean up broken links
+				"mkdir -p .local/state/{nix,home-manager}",
+				"chmod -R +w .local/state/{nix,home-manager}",
+				"rm -rf .local/state/{nix,home-manager}",
+				// run activation script
+				bundle.ActivationPackage + "/activate",
+			}, false, func(config *fst.Config) *fst.Config { return config },
+				bundle, pathSet, flagDropShellActivate, cleanup)
+
+			/*
+				Installation complete. Write metadata to block re-installs or downgrades.
+			*/
+
+			// serialise metadata to ensure consistency
+			if f, err := os.OpenFile(pathSet.metaPath+"~", os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644); err != nil {
+				cleanup()
+				log.Printf("cannot create metadata file: %v", err)
+				return err
+			} else if err = json.NewEncoder(f).Encode(bundle); err != nil {
+				cleanup()
+				log.Printf("cannot write metadata: %v", err)
+				return err
+			} else if err = f.Close(); err != nil {
+				log.Printf("cannot close metadata file: %v", err)
+				// not fatal
+			}
+
+			if err := os.Rename(pathSet.metaPath+"~", pathSet.metaPath); err != nil {
+				cleanup()
+				log.Printf("cannot rename metadata file: %v", err)
+				return err
+			}
+
+			cleanup()
+			return errSuccess
+		}).
+			Flag(&flagDropShellActivate, "s", command.BoolFlag(false), "Drop to a shell on activation")
+	}
+
+	{
+		var (
+			flagDropShellNixGL bool
+			flagAutoDrivers    bool
+		)
+		c.NewCommand("start", "Start an application", func(args []string) error {
+			if len(args) < 1 {
+				log.Println("invalid argument")
+				return syscall.EINVAL
+			}
+
+			/*
+				Parse app metadata.
+			*/
+
+			id := args[0]
+			pathSet := pathSetByApp(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
+			}
+
+			/*
+				Prepare nixGL.
+			*/
+
+			if a.GPU && flagAutoDrivers {
+				withNixDaemon(ctx, "nix-gl", []string{
+					"mkdir -p /nix/.nixGL/auto",
+					"rm -rf /nix/.nixGL/auto",
+					"export NIXPKGS_ALLOW_UNFREE=1",
+					"nix build --impure " +
+						"--out-link /nix/.nixGL/auto/opengl " +
+						"--override-input nixpkgs path:/etc/nixpkgs " +
+						"path:" + a.NixGL,
+					"nix build --impure " +
+						"--out-link /nix/.nixGL/auto/vulkan " +
+						"--override-input nixpkgs path:/etc/nixpkgs " +
+						"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"},
+						{Src: "/sys/block"},
+						{Src: "/sys/bus"},
+						{Src: "/sys/class"},
+						{Src: "/sys/dev"},
+						{Src: "/sys/devices"},
+					}...)
+					appendGPUFilesystem(config)
+					return config
+				}, a, pathSet, flagDropShellNixGL, func() {})
+			}
+
+			/*
+				Create app configuration.
+			*/
+
+			argv := make([]string, 1, len(args))
+			if !flagDropShell {
+				argv[0] = a.Launcher
+			} else {
+				argv[0] = shellPath
+			}
+			argv = append(argv, args[1:]...)
+
+			config := a.toFst(pathSet, argv, flagDropShell)
+
+			/*
+				Expose GPU devices.
+			*/
+
+			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)
+			}
+
+			/*
+				Spawn app.
+			*/
+
+			mustRunApp(ctx, config, func() {})
+			return errSuccess
+		}).
+			Flag(&flagDropShellNixGL, "s", command.BoolFlag(false), "Drop to a shell on nixGL build").
+			Flag(&flagAutoDrivers, "auto-drivers", command.BoolFlag(false), "Attempt automatic opengl driver detection")
+	}
+
+	c.MustParse(os.Args[1:], func(err error) {
+		fmsg.Verbosef("command returned %v", err)
+		if errors.Is(err, errSuccess) {
+			fmsg.BeforeExit()
+			os.Exit(0)
+		}
+	})
+	log.Fatal("unreachable")
 }

cmd/fpkg/paths.go

@@ -1,12 +1,14 @@
 package main
 
 import (
+	"log"
 	"os"
 	"os/exec"
 	"path"
 	"strconv"
 	"sync/atomic"
 
+	"git.gensokyo.uk/security/fortify/fst"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
@@ -25,8 +27,8 @@ func init() {
 
 func lookPath(file string) string {
 	if p, err := exec.LookPath(file); err != nil {
-		fmsg.Fatalf("%s: command not found", file)
-		panic("unreachable")
+		log.Fatalf("%s: command not found", file)
+		return ""
 	} else {
 		return p
 	}
@@ -35,15 +37,14 @@ func lookPath(file string) string {
 var beforeRunFail = new(atomic.Pointer[func()])
 
 func mustRun(name string, arg ...string) {
-	fmsg.VPrintf("spawning process: %q %q", name, arg)
+	fmsg.Verbosef("spawning process: %q %q", name, arg)
 	cmd := exec.Command(name, arg...)
 	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
 	if err := cmd.Run(); err != nil {
 		if f := beforeRunFail.Swap(nil); f != nil {
 			(*f)()
 		}
-		fmsg.Fatalf("%s: %v", name, err)
-		panic("unreachable")
+		log.Fatalf("%s: %v", name, err)
 	}
 }
 
@@ -69,3 +70,32 @@ func pathSetByApp(id string) *appPathSet {
 	pathSet.nixPath = path.Join(pathSet.cacheDir, "nix")
 	return pathSet
 }
+
+func appendGPUFilesystem(config *fst.Config) {
+	config.Confinement.Sandbox.Filesystem = append(config.Confinement.Sandbox.Filesystem, []*fst.FilesystemConfig{
+		// flatpak commit 763a686d874dd668f0236f911de00b80766ffe79
+		{Src: "/dev/dri", Device: true},
+		// mali
+		{Src: "/dev/mali", Device: true},
+		{Src: "/dev/mali0", Device: true},
+		{Src: "/dev/umplock", Device: true},
+		// nvidia
+		{Src: "/dev/nvidiactl", Device: true},
+		{Src: "/dev/nvidia-modeset", Device: true},
+		// nvidia OpenCL/CUDA
+		{Src: "/dev/nvidia-uvm", Device: true},
+		{Src: "/dev/nvidia-uvm-tools", Device: true},
+
+		// flatpak commit d2dff2875bb3b7e2cd92d8204088d743fd07f3ff
+		{Src: "/dev/nvidia0", Device: true}, {Src: "/dev/nvidia1", Device: true},
+		{Src: "/dev/nvidia2", Device: true}, {Src: "/dev/nvidia3", Device: true},
+		{Src: "/dev/nvidia4", Device: true}, {Src: "/dev/nvidia5", Device: true},
+		{Src: "/dev/nvidia6", Device: true}, {Src: "/dev/nvidia7", Device: true},
+		{Src: "/dev/nvidia8", Device: true}, {Src: "/dev/nvidia9", Device: true},
+		{Src: "/dev/nvidia10", Device: true}, {Src: "/dev/nvidia11", Device: true},
+		{Src: "/dev/nvidia12", Device: true}, {Src: "/dev/nvidia13", Device: true},
+		{Src: "/dev/nvidia14", Device: true}, {Src: "/dev/nvidia15", Device: true},
+		{Src: "/dev/nvidia16", Device: true}, {Src: "/dev/nvidia17", Device: true},
+		{Src: "/dev/nvidia18", Device: true}, {Src: "/dev/nvidia19", Device: true},
+	}...)
+}

cmd/fpkg/proc.go

@@ -1,70 +1,28 @@
 package main
 
 import (
-	"encoding/json"
-	"errors"
-	"io"
+	"context"
 	"os"
-	"os/exec"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal"
+	"git.gensokyo.uk/security/fortify/internal/app"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
-const compPoison = "INVALIDINVALIDINVALIDINVALIDINVALID"
+func mustRunApp(ctx context.Context, config *fst.Config, beforeFail func()) {
+	rs := new(fst.RunState)
+	a := app.MustNew(ctx, std)
 
-var (
-	Fmain = compPoison
-)
-
-func fortifyApp(config *fst.Config, beforeFail func()) {
-	var (
-		cmd *exec.Cmd
-		st  io.WriteCloser
-	)
-	if p, ok := internal.Path(Fmain); !ok {
-		beforeFail()
-		fmsg.Fatal("invalid fortify path, this copy of fpkg is not compiled correctly")
-		panic("unreachable")
-	} else if r, w, err := os.Pipe(); err != nil {
-		beforeFail()
-		fmsg.Fatalf("cannot pipe: %v", err)
-		panic("unreachable")
+	if sa, err := a.Seal(config); err != nil {
+		fmsg.PrintBaseError(err, "cannot seal app:")
+		rs.ExitCode = 1
 	} else {
-		if fmsg.Verbose() {
-			cmd = exec.Command(p, "-v", "app", "3")
-		} else {
-			cmd = exec.Command(p, "app", "3")
-		}
-		cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
-		cmd.ExtraFiles = []*os.File{r}
-		st = w
+		// this updates ExitCode
+		app.PrintRunStateErr(rs, sa.Run(rs))
 	}
 
-	go func() {
-		if err := json.NewEncoder(st).Encode(config); err != nil {
-			beforeFail()
-			fmsg.Fatalf("cannot send configuration: %v", err)
-			panic("unreachable")
-		}
-	}()
-
-	if err := cmd.Start(); err != nil {
+	if rs.ExitCode != 0 {
 		beforeFail()
-		fmsg.Fatalf("cannot start fortify: %v", err)
-		panic("unreachable")
-	}
-	if err := cmd.Wait(); err != nil {
-		var exitError *exec.ExitError
-		if errors.As(err, &exitError) {
-			beforeFail()
-			fmsg.Exit(exitError.ExitCode())
-			panic("unreachable")
-		} else {
-			beforeFail()
-			fmsg.Fatalf("cannot wait: %v", err)
-			panic("unreachable")
-		}
+		os.Exit(rs.ExitCode)
 	}
 }

cmd/fpkg/start.go

@@ -1,177 +0,0 @@
-package main
-
-import (
-	"flag"
-	"path"
-
-	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-func actionStart(args []string) {
-	set := flag.NewFlagSet("start", flag.ExitOnError)
-	var (
-		dropShell      bool
-		dropShellNixGL bool
-		autoDrivers    bool
-	)
-	set.BoolVar(&dropShell, "s", false, "Drop to a shell")
-	set.BoolVar(&dropShellNixGL, "sg", false, "Drop to a shell on nixGL build")
-	set.BoolVar(&autoDrivers, "autodrivers", false, "Attempt automatic opengl driver detection")
-
-	// Ignore errors; set is set for ExitOnError.
-	_ = set.Parse(args)
-
-	args = set.Args()
-
-	if len(args) < 1 {
-		fmsg.Fatal("invalid argument")
-	}
-
-	/*
-		Parse app metadata.
-	*/
-
-	id := args[0]
-	pathSet := pathSetByApp(id)
-	app := loadBundleInfo(pathSet.metaPath, func() {})
-	if app.ID != id {
-		fmsg.Fatalf("app %q claims to have identifier %q", id, app.ID)
-	}
-
-	/*
-		Prepare nixGL.
-	*/
-
-	if app.GPU && autoDrivers {
-		withNixDaemon("nix-gl", []string{
-			"mkdir -p /nix/.nixGL/auto",
-			"rm -rf /nix/.nixGL/auto",
-			"export NIXPKGS_ALLOW_UNFREE=1",
-			"nix build --impure " +
-				"--out-link /nix/.nixGL/auto/opengl " +
-				"--override-input nixpkgs path:/etc/nixpkgs " +
-				"path:" + app.NixGL,
-			"nix build --impure " +
-				"--out-link /nix/.nixGL/auto/vulkan " +
-				"--override-input nixpkgs path:/etc/nixpkgs " +
-				"path:" + app.NixGL + "#nixVulkanNvidia",
-		}, true, func(config *fst.Config) *fst.Config {
-			config.Confinement.Sandbox.Filesystem = append(config.Confinement.Sandbox.Filesystem, []*fst.FilesystemConfig{
-				{Src: "/etc/resolv.conf"},
-				{Src: "/sys/block"},
-				{Src: "/sys/bus"},
-				{Src: "/sys/class"},
-				{Src: "/sys/dev"},
-				{Src: "/sys/devices"},
-			}...)
-			appendGPUFilesystem(config)
-			return config
-		}, app, pathSet, dropShellNixGL, func() {})
-	}
-
-	/*
-		Create app configuration.
-	*/
-
-	command := make([]string, 1, len(args))
-	if !dropShell {
-		command[0] = app.Launcher
-	} else {
-		command[0] = shell
-	}
-	command = append(command, args[1:]...)
-
-	config := &fst.Config{
-		ID:      app.ID,
-		Command: command,
-		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 || dropShell,
-				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,
-		},
-	}
-
-	/*
-		Expose GPU devices.
-	*/
-
-	if app.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)
-	}
-
-	/*
-		Spawn app.
-	*/
-
-	fortifyApp(config, func() {})
-	fmsg.Exit(0)
-}
-
-func appendGPUFilesystem(config *fst.Config) {
-	config.Confinement.Sandbox.Filesystem = append(config.Confinement.Sandbox.Filesystem, []*fst.FilesystemConfig{
-		// flatpak commit 763a686d874dd668f0236f911de00b80766ffe79
-		{Src: "/dev/dri", Device: true},
-		// mali
-		{Src: "/dev/mali", Device: true},
-		{Src: "/dev/mali0", Device: true},
-		{Src: "/dev/umplock", Device: true},
-		// nvidia
-		{Src: "/dev/nvidiactl", Device: true},
-		{Src: "/dev/nvidia-modeset", Device: true},
-		// nvidia OpenCL/CUDA
-		{Src: "/dev/nvidia-uvm", Device: true},
-		{Src: "/dev/nvidia-uvm-tools", Device: true},
-
-		// flatpak commit d2dff2875bb3b7e2cd92d8204088d743fd07f3ff
-		{Src: "/dev/nvidia0", Device: true}, {Src: "/dev/nvidia1", Device: true},
-		{Src: "/dev/nvidia2", Device: true}, {Src: "/dev/nvidia3", Device: true},
-		{Src: "/dev/nvidia4", Device: true}, {Src: "/dev/nvidia5", Device: true},
-		{Src: "/dev/nvidia6", Device: true}, {Src: "/dev/nvidia7", Device: true},
-		{Src: "/dev/nvidia8", Device: true}, {Src: "/dev/nvidia9", Device: true},
-		{Src: "/dev/nvidia10", Device: true}, {Src: "/dev/nvidia11", Device: true},
-		{Src: "/dev/nvidia12", Device: true}, {Src: "/dev/nvidia13", Device: true},
-		{Src: "/dev/nvidia14", Device: true}, {Src: "/dev/nvidia15", Device: true},
-		{Src: "/dev/nvidia16", Device: true}, {Src: "/dev/nvidia17", Device: true},
-		{Src: "/dev/nvidia18", Device: true}, {Src: "/dev/nvidia19", Device: true},
-	}...)
-}

cmd/fpkg/test/configuration.nix

@@ -0,0 +1,60 @@
+{ pkgs, ... }:
+{
+  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 = {
+    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 = {
+    diskSize = 6 * 1024;
+
+    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 zstd performance:
+      "-smp 8"
+    ];
+  };
+
+  environment.fortify = {
+    enable = true;
+    stateDir = "/var/lib/fortify";
+    users.alice = 0;
+
+    home-manager = _: _: { home.stateVersion = "23.05"; };
+  };
+}

cmd/fpkg/test/default.nix

@@ -0,0 +1,34 @@
+{
+  nixosTest,
+  callPackage,
+
+  system,
+  self,
+}:
+let
+  buildPackage = self.buildPackage.${system};
+in
+nixosTest {
+  name = "fpkg";
+  nodes.machine = {
+    environment.etc = {
+      "foot.pkg".source = callPackage ./foot.nix { inherit buildPackage; };
+    };
+
+    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;
+}

cmd/fpkg/test/foot.nix

@@ -0,0 +1,48 @@
+{
+  lib,
+  buildPackage,
+  foot,
+  wayland-utils,
+  inconsolata,
+}:
+
+buildPackage {
+  name = "foot";
+  inherit (foot) version;
+
+  app_id = 2;
+  id = "org.codeberg.dnkl.foot";
+
+  modules = [
+    {
+      home.packages = [
+        foot
+
+        # For wayland-info:
+        wayland-utils
+      ];
+    }
+  ];
+
+  nixosModules = [
+    {
+      # To help with OCR:
+      environment.etc."xdg/foot/foot.ini".text = lib.generators.toINI { } {
+        main = {
+          font = "inconsolata:size=14";
+        };
+        colors = rec {
+          foreground = "000000";
+          background = "ffffff";
+          regular2 = foreground;
+        };
+      };
+
+      fonts.packages = [ inconsolata ];
+    }
+  ];
+
+  script = ''
+    exec foot "$@"
+  '';
+}

cmd/fpkg/test/test.py

@@ -0,0 +1,108 @@
+import json
+import shlex
+
+q = shlex.quote
+NODE_GROUPS = ["nodes", "floating_nodes"]
+
+
+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
+
+
+def walk(tree):
+    yield tree
+    for group in NODE_GROUPS:
+        for node in tree.get(group, []):
+            yield from walk(node)
+
+
+def wait_for_window(pattern):
+    def func(last_chance):
+        nodes = (node["name"] for node in walk(swaymsg(type="get_tree")))
+
+        if last_chance:
+            nodes = list(nodes)
+            machine.log(f"Last call! Current list of windows: {nodes}")
+
+        return any(pattern in name for name in nodes)
+
+    retry(func)
+
+
+def collect_state_ui(name):
+    swaymsg(f"exec fortify ps > '/tmp/{name}.ps'")
+    machine.copy_from_vm(f"/tmp/{name}.ps", "")
+    swaymsg(f"exec fortify --json ps > '/tmp/{name}.json'")
+    machine.copy_from_vm(f"/tmp/{name}.json", "")
+    machine.screenshot(name)
+
+
+def check_state(name, enablements):
+    instances = json.loads(machine.succeed("sudo -u alice -i XDG_RUNTIME_DIR=/run/user/1000 fortify --json ps"))
+    if len(instances) != 1:
+        raise Exception(f"unexpected state length {len(instances)}")
+    instance = next(iter(instances.values()))
+
+    config = instance['config']
+
+    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']}")
+
+
+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")
+
+# Prepare fpkg directory:
+machine.succeed("install -dm 0700 -o alice -g users /var/lib/fortify/1000")
+
+# Install fpkg app:
+swaymsg("exec fpkg -v install /etc/foot.pkg && touch /tmp/fpkg-install-done")
+machine.wait_for_file("/tmp/fpkg-install-done")
+
+# Start app (foot) with Wayland enablement:
+swaymsg("exec fpkg -v start org.codeberg.dnkl.foot")
+wait_for_window("fortify@machine-foot")
+machine.send_chars("clear; wayland-info && touch /tmp/success-client\n")
+machine.wait_for_file("/tmp/fortify.1000/tmpdir/2/success-client")
+collect_state_ui("app_wayland")
+check_state("foot", 13)
+# Verify acl on XDG_RUNTIME_DIR:
+print(machine.succeed("getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep 1000002"))
+machine.send_chars("exit\n")
+machine.wait_until_fails("pgrep foot")
+# Verify acl cleanup on XDG_RUNTIME_DIR:
+machine.wait_until_fails("getfacl --absolute-names --omit-header --numeric /run/user/1000 | grep 1000002")
+
+# 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"))

cmd/fpkg/with.go

@@ -1,21 +1,24 @@
 package main
 
 import (
+	"context"
 	"path"
 	"strings"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"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(),
 ) {
-	fortifyAppDropShell(updateConfig(&fst.Config{
-		ID: app.ID,
-		Command: []string{shell, "-lc", "rm -f /nix/var/nix/daemon-socket/socket && " +
+	mustRunAppDropShell(ctx, updateConfig(&fst.Config{
+		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
@@ -31,12 +34,13 @@ 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
-				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},
 				},
@@ -56,19 +60,24 @@ func withNixDaemon(
 	}), dropShell, beforeFail)
 }
 
-func withCacheDir(action string, command []string, workDir string, app *bundleInfo, pathSet *appPathSet, dropShell bool, beforeFail func()) {
-	fortifyAppDropShell(&fst.Config{
-		ID:      app.ID,
-		Command: []string{shell, "-lc", strings.Join(command, " && ")},
+func withCacheDir(
+	ctx context.Context,
+	action string, command []string, workDir string,
+	app *appInfo, pathSet *appPathSet, dropShell bool, beforeFail func()) {
+	mustRunAppDropShell(ctx, &fst.Config{
+		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
+			Shell:    shellPath,
 			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},
@@ -90,12 +99,12 @@ func withCacheDir(action string, command []string, workDir string, app *bundleIn
 	}, dropShell, beforeFail)
 }
 
-func fortifyAppDropShell(config *fst.Config, dropShell bool, beforeFail func()) {
+func mustRunAppDropShell(ctx context.Context, config *fst.Config, dropShell bool, beforeFail func()) {
 	if dropShell {
-		config.Command = []string{shell, "-l"}
-		fortifyApp(config, beforeFail)
+		config.Args = []string{shellPath, "-l"}
+		mustRunApp(ctx, config, beforeFail)
 		beforeFail()
-		fmsg.Exit(0)
+		internal.Exit(0)
 	}
-	fortifyApp(config, beforeFail)
+	mustRunApp(ctx, config, beforeFail)
 }

cmd/fsu/main.go

@@ -13,7 +13,6 @@ import (
 )
 
 const (
-	compPoison  = "INVALIDINVALIDINVALIDINVALIDINVALID"
 	fsuConfFile = "/etc/fsurc"
 	envShim     = "FORTIFY_SHIM"
 	envAID      = "FORTIFY_APP_ID"
@@ -22,10 +21,6 @@ const (
 	PR_SET_NO_NEW_PRIVS = 0x26
 )
 
-var (
-	Fmain = compPoison
-)
-
 func main() {
 	log.SetFlags(0)
 	log.SetPrefix("fsu: ")
@@ -40,20 +35,16 @@ func main() {
 		log.Fatal("this program must not be started by root")
 	}
 
-	var fmain string
-	if p, ok := checkPath(Fmain); !ok {
-		log.Fatal("invalid fortify path, this copy of fsu is not compiled correctly")
-	} else {
-		fmain = p
-	}
-
+	var toolPath string
 	pexe := path.Join("/proc", strconv.Itoa(os.Getppid()), "exe")
 	if p, err := os.Readlink(pexe); err != nil {
 		log.Fatalf("cannot read parent executable path: %v", err)
 	} else if strings.HasSuffix(p, " (deleted)") {
 		log.Fatal("fortify executable has been deleted")
-	} else if p != fmain {
+	} else if p != mustCheckPath(fmain) && p != mustCheckPath(fpkg) {
 		log.Fatal("this program must be started by fortify")
+	} else {
+		toolPath = p
 	}
 
 	// uid = 1000000 +
@@ -147,13 +138,9 @@ func main() {
 	if _, _, errno := syscall.AllThreadsSyscall(syscall.SYS_PRCTL, PR_SET_NO_NEW_PRIVS, 1, 0); errno != 0 {
 		log.Fatalf("cannot set no_new_privs flag: %s", errno.Error())
 	}
-	if err := syscall.Exec(fmain, []string{"fortify", "shim"}, []string{envShim + "=" + shimSetupFd}); err != nil {
+	if err := syscall.Exec(toolPath, []string{"fortify", "shim"}, []string{envShim + "=" + shimSetupFd}); err != nil {
 		log.Fatalf("cannot start shim: %v", err)
 	}
 
 	panic("unreachable")
 }
-
-func checkPath(p string) (string, bool) {
-	return p, p != compPoison && p != "" && path.IsAbs(p)
-}

cmd/fsu/package.nix

@@ -0,0 +1,30 @@
+{
+  lib,
+  buildGoModule,
+  fortify ? abort "fortify package required",
+}:
+
+buildGoModule {
+  pname = "${fortify.pname}-fsu";
+  inherit (fortify) version;
+
+  src = ./.;
+  inherit (fortify) vendorHash;
+  CGO_ENABLED = 0;
+
+  preBuild = ''
+    go mod init fsu >& /dev/null
+  '';
+
+  ldflags =
+    lib.attrsets.foldlAttrs
+      (
+        ldflags: name: value:
+        ldflags ++ [ "-X main.${name}=${value}" ]
+      )
+      [ "-s -w" ]
+      {
+        fmain = "${fortify}/libexec/fortify";
+        fpkg = "${fortify}/libexec/fpkg";
+      };
+}

cmd/fsu/path.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"log"
+	"path"
+)
+
+const compPoison = "INVALIDINVALIDINVALIDINVALIDINVALID"
+
+var (
+	fmain = compPoison
+	fpkg  = compPoison
+)
+
+func mustCheckPath(p string) string {
+	if p != compPoison && p != "" && path.IsAbs(p) {
+		return p
+	}
+	log.Fatal("this program is compiled incorrectly")
+	return compPoison
+}

command/builder.go

@@ -0,0 +1,65 @@
+package command
+
+import (
+	"flag"
+	"fmt"
+	"io"
+)
+
+// New initialises a root Node.
+func New(output io.Writer, logf LogFunc, name string, early HandlerFunc) Command {
+	c := rootNode{newNode(output, logf, name, "")}
+	c.f = early
+	return c
+}
+
+func newNode(output io.Writer, logf LogFunc, name, usage string) *node {
+	n := &node{
+		name: name, usage: usage,
+		out: output, logf: logf,
+		set: flag.NewFlagSet(name, flag.ContinueOnError),
+	}
+	n.set.SetOutput(output)
+	n.set.Usage = func() {
+		_ = n.writeHelp()
+		if n.suffix.Len() > 0 {
+			_, _ = fmt.Fprintln(output, "Flags:")
+			n.set.PrintDefaults()
+			_, _ = fmt.Fprintln(output)
+		}
+	}
+
+	return n
+}
+
+func (n *node) Command(name, usage string, f HandlerFunc) Node {
+	n.NewCommand(name, usage, f)
+	return n
+}
+
+func (n *node) NewCommand(name, usage string, f HandlerFunc) Flag[Node] {
+	if f == nil {
+		panic("invalid handler")
+	}
+	if name == "" || usage == "" {
+		panic("invalid subcommand")
+	}
+
+	s := newNode(n.out, n.logf, name, usage)
+	s.f = f
+	if !n.adopt(s) {
+		panic("attempted to initialise subcommand with non-unique name")
+	}
+	return s
+}
+
+func (n *node) New(name, usage string) Node {
+	if name == "" || usage == "" {
+		panic("invalid subcommand tree")
+	}
+	s := newNode(n.out, n.logf, name, usage)
+	if !n.adopt(s) {
+		panic("attempted to initialise subcommand tree with non-unique name")
+	}
+	return s
+}

command/builder_test.go

@@ -0,0 +1,56 @@
+package command_test
+
+import (
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/command"
+)
+
+func TestBuild(t *testing.T) {
+	c := command.New(nil, nil, "test", nil)
+	stubHandler := func([]string) error { panic("unreachable") }
+
+	t.Run("nil direct handler", func(t *testing.T) {
+		defer checkRecover(t, "Command", "invalid handler")
+		c.Command("name", "usage", nil)
+	})
+
+	t.Run("direct zero length", func(t *testing.T) {
+		wantPanic := "invalid subcommand"
+		t.Run("zero length name", func(t *testing.T) { defer checkRecover(t, "Command", wantPanic); c.Command("", "usage", stubHandler) })
+		t.Run("zero length usage", func(t *testing.T) { defer checkRecover(t, "Command", wantPanic); c.Command("name", "", stubHandler) })
+	})
+
+	t.Run("direct adopt unique names", func(t *testing.T) {
+		c.Command("d0", "usage", stubHandler)
+		c.Command("d1", "usage", stubHandler)
+	})
+
+	t.Run("direct adopt non-unique name", func(t *testing.T) {
+		defer checkRecover(t, "Command", "attempted to initialise subcommand with non-unique name")
+		c.Command("d0", "usage", stubHandler)
+	})
+
+	t.Run("zero length", func(t *testing.T) {
+		wantPanic := "invalid subcommand tree"
+		t.Run("zero length name", func(t *testing.T) { defer checkRecover(t, "New", wantPanic); c.New("", "usage") })
+		t.Run("zero length usage", func(t *testing.T) { defer checkRecover(t, "New", wantPanic); c.New("name", "") })
+	})
+
+	t.Run("direct adopt unique names", func(t *testing.T) {
+		c.New("t0", "usage")
+		c.New("t1", "usage")
+	})
+
+	t.Run("direct adopt non-unique name", func(t *testing.T) {
+		defer checkRecover(t, "Command", "attempted to initialise subcommand tree with non-unique name")
+		c.New("t0", "usage")
+	})
+}
+
+func checkRecover(t *testing.T, name, wantPanic string) {
+	if r := recover(); r != wantPanic {
+		t.Errorf("%s: panic = %v; wantPanic %v",
+			name, r, wantPanic)
+	}
+}

command/command.go

@@ -0,0 +1,55 @@
+// Package command implements generic nested command parsing.
+package command
+
+import (
+	"flag"
+	"strings"
+)
+
+// UsageInternal causes the command to be hidden from help text when set as the usage string.
+const UsageInternal = "internal"
+
+type (
+	// HandlerFunc is called when matching a directly handled subcommand tree.
+	HandlerFunc = func(args []string) error
+
+	// LogFunc is the function signature of a printf function.
+	LogFunc = func(format string, a ...any)
+
+	// FlagDefiner is a deferred flag definer value, usually encapsulating the default value.
+	FlagDefiner interface {
+		// Define defines the flag in set.
+		Define(b *strings.Builder, set *flag.FlagSet, p any, name, usage string)
+	}
+
+	Flag[T any] interface {
+		// Flag defines a generic flag type in Node's flag set.
+		Flag(p any, name string, value FlagDefiner, usage string) T
+	}
+
+	Command interface {
+		Parse(arguments []string) error
+
+		// MustParse determines exit outcomes for Parse errors
+		// and calls handleError if [HandlerFunc] returns a non-nil error.
+		MustParse(arguments []string, handleError func(error))
+
+		baseNode[Command]
+	}
+	Node baseNode[Node]
+
+	baseNode[T any] interface {
+		// Command appends a subcommand with direct command handling.
+		Command(name, usage string, f HandlerFunc) T
+
+		// New returns a new subcommand tree.
+		New(name, usage string) (sub Node)
+		// NewCommand returns a new subcommand with direct command handling.
+		NewCommand(name, usage string, f HandlerFunc) (sub Flag[Node])
+
+		// PrintHelp prints a help message to the configured writer.
+		PrintHelp()
+
+		Flag[T]
+	}
+)

command/flag.go

@@ -0,0 +1,77 @@
+package command
+
+import (
+	"errors"
+	"flag"
+	"strings"
+)
+
+// FlagError wraps errors returned by [flag].
+type FlagError struct{ error }
+
+func (e FlagError) Success() bool { return errors.Is(e.error, flag.ErrHelp) }
+func (e FlagError) Is(target error) bool {
+	return (e.error == nil && target == nil) ||
+		((e.error != nil && target != nil) && e.error.Error() == target.Error())
+}
+
+func (n *node) Flag(p any, name string, value FlagDefiner, usage string) Node {
+	value.Define(&n.suffix, n.set, p, name, usage)
+	return n
+}
+
+// StringFlag is the default value of a string flag.
+type StringFlag string
+
+func (v StringFlag) Define(b *strings.Builder, set *flag.FlagSet, p any, name, usage string) {
+	set.StringVar(p.(*string), name, string(v), usage)
+	b.WriteString(" [" + prettyFlag(name) + " <value>]")
+}
+
+// IntFlag is the default value of an int flag.
+type IntFlag int
+
+func (v IntFlag) Define(b *strings.Builder, set *flag.FlagSet, p any, name, usage string) {
+	set.IntVar(p.(*int), name, int(v), usage)
+	b.WriteString(" [" + prettyFlag(name) + " <int>]")
+}
+
+// BoolFlag is the default value of a bool flag.
+type BoolFlag bool
+
+func (v BoolFlag) Define(b *strings.Builder, set *flag.FlagSet, p any, name, usage string) {
+	set.BoolVar(p.(*bool), name, bool(v), usage)
+	b.WriteString(" [" + prettyFlag(name) + "]")
+}
+
+// RepeatableFlag implements an ordered, repeatable string flag.
+type RepeatableFlag []string
+
+func (r *RepeatableFlag) String() string {
+	if r == nil {
+		return "<nil>"
+	}
+	return strings.Join(*r, " ")
+}
+
+func (r *RepeatableFlag) Set(v string) error {
+	*r = append(*r, v)
+	return nil
+}
+
+func (r *RepeatableFlag) Define(b *strings.Builder, set *flag.FlagSet, _ any, name, usage string) {
+	set.Var(r, name, usage)
+	b.WriteString(" [" + prettyFlag(name) + " <value>]")
+}
+
+// this has no effect on parse outcome
+func prettyFlag(name string) string {
+	switch len(name) {
+	case 0:
+		panic("zero length flag name")
+	case 1:
+		return "-" + name
+	default:
+		return "--" + name
+	}
+}

command/help.go

@@ -0,0 +1,53 @@
+package command
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"text/tabwriter"
+)
+
+var ErrHelp = errors.New("help requested")
+
+func (n *node) PrintHelp() { _ = n.writeHelp() }
+
+func (n *node) writeHelp() error {
+	if _, err := fmt.Fprintf(n.out,
+		"\nUsage:\t%s [-h | --help]%s COMMAND [OPTIONS]\n",
+		strings.Join(append(n.prefix, n.name), " "), &n.suffix,
+	); err != nil {
+		return err
+	}
+	if n.child != nil {
+		if _, err := fmt.Fprint(n.out, "\nCommands:\n"); err != nil {
+			return err
+		}
+	}
+
+	tw := tabwriter.NewWriter(n.out, 0, 1, 4, ' ', 0)
+	if err := n.child.writeCommands(tw); err != nil {
+		return err
+	}
+	if err := tw.Flush(); err != nil {
+		return err
+	}
+
+	_, err := n.out.Write([]byte{'\n'})
+	if err == nil {
+		err = ErrHelp
+	}
+	return err
+}
+
+func (n *node) writeCommands(w io.Writer) error {
+	if n == nil {
+		return nil
+	}
+	if n.usage != UsageInternal {
+		if _, err := fmt.Fprintf(w, "\t%s\t%s\n", n.name, n.usage); err != nil {
+			return err
+		}
+	}
+	return n.next.writeCommands(w)
+}

command/node.go

@@ -0,0 +1,40 @@
+package command
+
+import (
+	"flag"
+	"io"
+	"strings"
+)
+
+type node struct {
+	child, next *node
+	name, usage string
+
+	out  io.Writer
+	logf LogFunc
+
+	prefix []string
+	suffix strings.Builder
+
+	f   HandlerFunc
+	set *flag.FlagSet
+}
+
+func (n *node) adopt(v *node) bool {
+	if n.child != nil {
+		return n.child.append(v)
+	}
+	n.child = v
+	return true
+}
+
+func (n *node) append(v *node) bool {
+	if n.name == v.name {
+		return false
+	}
+	if n.next != nil {
+		return n.next.append(v)
+	}
+	n.next = v
+	return true
+}

command/parse.go

@@ -0,0 +1,105 @@
+package command
+
+import (
+	"errors"
+	"log"
+	"os"
+)
+
+var (
+	ErrEmptyTree = errors.New("subcommand tree has no nodes")
+	ErrNoMatch   = errors.New("did not match any subcommand")
+)
+
+func (n *node) Parse(arguments []string) error {
+	if n.usage == "" { // root node has zero length usage
+		if n.next != nil {
+			panic("invalid toplevel state")
+		}
+		goto match
+	}
+
+	if len(arguments) == 0 {
+		// unreachable: zero length args cause upper level to return with a help message
+		panic("attempted to parse with zero length args")
+	}
+	if arguments[0] != n.name {
+		if n.next == nil {
+			n.printf("%q is not a valid command", arguments[0])
+			return ErrNoMatch
+		}
+		n.next.prefix = n.prefix
+		return n.next.Parse(arguments)
+	}
+	arguments = arguments[1:]
+
+match:
+	if n.child != nil {
+		// propagate help prefix early: flag set usage dereferences help
+		n.child.prefix = append(n.prefix, n.name)
+	}
+
+	if n.set.Parsed() {
+		panic("invalid set state")
+	}
+	if err := n.set.Parse(arguments); err != nil {
+		return FlagError{err}
+	}
+	args := n.set.Args()
+
+	if n.child != nil {
+		if n.f != nil {
+			if n.usage != "" { // root node early special case
+				panic("invalid subcommand tree state")
+			}
+
+			// special case: root node calls HandlerFunc for initialisation
+			if err := n.f(nil); err != nil {
+				return err
+			}
+		}
+
+		if len(args) == 0 {
+			return n.writeHelp()
+		}
+		return n.child.Parse(args)
+	}
+
+	if n.f == nil {
+		n.printf("%q has no subcommands", n.name)
+		return ErrEmptyTree
+	}
+	return n.f(args)
+}
+
+func (n *node) printf(format string, a ...any) {
+	if n.logf == nil {
+		log.Printf(format, a...)
+	} else {
+		n.logf(format, a...)
+	}
+}
+
+func (n *node) MustParse(arguments []string, handleError func(error)) {
+	switch err := n.Parse(arguments); err {
+	case nil:
+		return
+	case ErrHelp:
+		os.Exit(0)
+	case ErrNoMatch:
+		os.Exit(1)
+	case ErrEmptyTree:
+		os.Exit(1)
+	default:
+		var flagError FlagError
+		if !errors.As(err, &flagError) { // returned by HandlerFunc
+			handleError(err)
+			os.Exit(1)
+		}
+
+		if flagError.Success() {
+			os.Exit(0)
+		}
+		os.Exit(1)
+	}
+}

command/parse_test.go

@@ -0,0 +1,344 @@
+package command_test
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"strings"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/command"
+)
+
+func TestParse(t *testing.T) {
+	testCases := []struct {
+		name      string
+		buildTree func(wout, wlog io.Writer) command.Command
+		args      []string
+		want      string
+		wantLog   string
+		wantErr   error
+	}{
+		{
+			"d=0 empty sub",
+			func(wout, wlog io.Writer) command.Command { return command.New(wout, newLogFunc(wlog), "root", nil) },
+			[]string{""},
+			"", "test: \"root\" has no subcommands\n", command.ErrEmptyTree,
+		},
+		{
+			"d=0 empty sub garbage",
+			func(wout, wlog io.Writer) command.Command { return command.New(wout, newLogFunc(wlog), "root", nil) },
+			[]string{"a", "b", "c", "d"},
+			"", "test: \"root\" has no subcommands\n", command.ErrEmptyTree,
+		},
+		{
+			"d=0 no match",
+			buildTestCommand,
+			[]string{"nonexistent"},
+			"", "test: \"nonexistent\" is not a valid command\n", command.ErrNoMatch,
+		},
+		{
+			"d=0 direct error",
+			buildTestCommand,
+			[]string{"error"},
+			"", "", errSuccess,
+		},
+		{
+			"d=0 direct error garbage",
+			buildTestCommand,
+			[]string{"error", "0", "1", "2"},
+			"", "", errSuccess,
+		},
+		{
+			"d=0 direct success out of order",
+			buildTestCommand,
+			[]string{"succeed"},
+			"", "", nil,
+		},
+		{
+			"d=0 direct success output",
+			buildTestCommand,
+			[]string{"print", "0", "1", "2"},
+			"012", "", nil,
+		},
+		{
+			"d=0 out of order string flag",
+			buildTestCommand,
+			[]string{"string", "--string", "64d3b4b7b21788585845060e2199a78f"},
+			"flag provided but not defined: -string\n\nUsage:\ttest string [-h | --help] COMMAND [OPTIONS]\n\n", "",
+			errors.New("flag provided but not defined: -string"),
+		},
+		{
+			"d=0 string flag",
+			buildTestCommand,
+			[]string{"--string", "64d3b4b7b21788585845060e2199a78f", "string"},
+			"64d3b4b7b21788585845060e2199a78f", "", nil,
+		},
+		{
+			"d=0 int flag",
+			buildTestCommand,
+			[]string{"--int", "2147483647", "int"},
+			"2147483647", "", nil,
+		},
+		{
+			"d=0 repeat flag",
+			buildTestCommand,
+			[]string{"--repeat", "0", "--repeat", "1", "--repeat", "2", "--repeat", "3", "--repeat", "4", "repeat"},
+			"[0 1 2 3 4]", "", nil,
+		},
+		{
+			"d=0 bool flag",
+			buildTestCommand,
+			[]string{"-v", "succeed"},
+			"", "test: verbose\n", nil,
+		},
+		{
+			"d=0 bool flag early error",
+			buildTestCommand,
+			[]string{"--fail", "succeed"},
+			"", "", errSuccess,
+		},
+
+		{
+			"d=1 empty sub",
+			buildTestCommand,
+			[]string{"empty"},
+			"", "test: \"empty\" has no subcommands\n", command.ErrEmptyTree,
+		},
+		{
+			"d=1 empty sub garbage",
+			buildTestCommand,
+			[]string{"empty", "a", "b", "c", "d"},
+			"", "test: \"empty\" has no subcommands\n", command.ErrEmptyTree,
+		},
+		{
+			"d=1 empty sub help",
+			buildTestCommand,
+			[]string{"empty", "-h"},
+			"\nUsage:\ttest empty [-h | --help] COMMAND [OPTIONS]\n\n", "", flag.ErrHelp,
+		},
+		{
+			"d=1 no match",
+			buildTestCommand,
+			[]string{"join", "23aa3bb0", "34986782", "d8859355", "cd9ac317", ", "},
+			"", "test: \"23aa3bb0\" is not a valid command\n", command.ErrNoMatch,
+		},
+		{
+			"d=1 direct success out",
+			buildTestCommand,
+			[]string{"join", "out", "23aa3bb0", "34986782", "d8859355", "cd9ac317", ", "},
+			"23aa3bb0, 34986782, d8859355, cd9ac317", "", nil,
+		},
+		{
+			"d=1 direct success log",
+			buildTestCommand,
+			[]string{"join", "log", "23aa3bb0", "34986782", "d8859355", "cd9ac317", ", "},
+			"", "test: 23aa3bb0, 34986782, d8859355, cd9ac317\n", nil,
+		},
+
+		{
+			"d=4 empty sub",
+			buildTestCommand,
+			[]string{"deep", "d=2", "d=3", "d=4"},
+			"", "test: \"d=4\" has no subcommands\n", command.ErrEmptyTree},
+
+		{
+			"d=0 help",
+			buildTestCommand,
+			[]string{},
+			`
+Usage:	test [-h | --help] [-v] [--fail] [--string <value>] [--int <int>] [--repeat <value>] COMMAND [OPTIONS]
+
+Commands:
+    error      return an error
+    print      wraps Fprint
+    string     print string passed by flag
+    int        print int passed by flag
+    repeat     print repeated values passed by flag
+    empty      empty subcommand
+    join       wraps strings.Join
+    succeed    this command succeeds
+    deep       top level of command tree with various levels
+
+`, "", command.ErrHelp,
+		},
+		{
+			"d=0 help flag",
+			buildTestCommand,
+			[]string{"-h"},
+			`
+Usage:	test [-h | --help] [-v] [--fail] [--string <value>] [--int <int>] [--repeat <value>] COMMAND [OPTIONS]
+
+Commands:
+    error      return an error
+    print      wraps Fprint
+    string     print string passed by flag
+    int        print int passed by flag
+    repeat     print repeated values passed by flag
+    empty      empty subcommand
+    join       wraps strings.Join
+    succeed    this command succeeds
+    deep       top level of command tree with various levels
+
+Flags:
+  -fail
+    	fail early
+  -int int
+    	store value for the "int" command (default -1)
+  -repeat value
+    	store value for the "repeat" command
+  -string string
+    	store value for the "string" command (default "default")
+  -v	verbose output
+
+`, "", flag.ErrHelp,
+		},
+
+		{
+			"d=1 help",
+			buildTestCommand,
+			[]string{"join"},
+			`
+Usage:	test join [-h | --help] COMMAND [OPTIONS]
+
+Commands:
+    out    write result to wout
+    log    log result to wlog
+
+`, "", command.ErrHelp,
+		},
+		{
+			"d=1 help flag",
+			buildTestCommand,
+			[]string{"join", "-h"},
+			`
+Usage:	test join [-h | --help] COMMAND [OPTIONS]
+
+Commands:
+    out    write result to wout
+    log    log result to wlog
+
+`, "", flag.ErrHelp,
+		},
+
+		{
+			"d=2 help",
+			buildTestCommand,
+			[]string{"deep", "d=2"},
+			`
+Usage:	test deep d=2 [-h | --help] COMMAND [OPTIONS]
+
+Commands:
+    d=3    relative third level
+
+`, "", command.ErrHelp,
+		},
+		{
+			"d=2 help flag",
+			buildTestCommand,
+			[]string{"deep", "d=2", "-h"},
+			`
+Usage:	test deep d=2 [-h | --help] COMMAND [OPTIONS]
+
+Commands:
+    d=3    relative third level
+
+`, "", flag.ErrHelp,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			wout, wlog := new(bytes.Buffer), new(bytes.Buffer)
+			c := tc.buildTree(wout, wlog)
+
+			if err := c.Parse(tc.args); !errors.Is(err, tc.wantErr) {
+				t.Errorf("Parse: error = %v; wantErr %v", err, tc.wantErr)
+			}
+			if got := wout.String(); got != tc.want {
+				t.Errorf("Parse: %s want %s", got, tc.want)
+			}
+			if gotLog := wlog.String(); gotLog != tc.wantLog {
+				t.Errorf("Parse: log = %s wantLog %s", gotLog, tc.wantLog)
+			}
+		})
+	}
+}
+
+var (
+	errJoinLen = errors.New("not enough arguments to join")
+	errSuccess = errors.New("success")
+)
+
+func buildTestCommand(wout, wlog io.Writer) (c command.Command) {
+	var (
+		flagVerbose bool
+		flagFail    bool
+
+		flagString string
+		flagInt    int
+		flagRepeat command.RepeatableFlag
+	)
+
+	logf := newLogFunc(wlog)
+	c = command.New(wout, logf, "test", func([]string) error {
+		if flagVerbose {
+			logf("verbose")
+		}
+		if flagFail {
+			return errSuccess
+		}
+		return nil
+	}).
+		Flag(&flagVerbose, "v", command.BoolFlag(false), "verbose output").
+		Flag(&flagFail, "fail", command.BoolFlag(false), "fail early").
+		Command("error", "return an error", func([]string) error {
+			return errSuccess
+		}).
+		Command("print", "wraps Fprint", func(args []string) error {
+			a := make([]any, len(args))
+			for i, v := range args {
+				a[i] = v
+			}
+			_, err := fmt.Fprint(wout, a...)
+			return err
+		}).
+		Flag(&flagString, "string", command.StringFlag("default"), "store value for the \"string\" command").
+		Command("string", "print string passed by flag", func(args []string) error { _, err := fmt.Fprint(wout, flagString); return err }).
+		Flag(&flagInt, "int", command.IntFlag(-1), "store value for the \"int\" command").
+		Command("int", "print int passed by flag", func(args []string) error { _, err := fmt.Fprint(wout, flagInt); return err }).
+		Flag(nil, "repeat", &flagRepeat, "store value for the \"repeat\" command").
+		Command("repeat", "print repeated values passed by flag", func(args []string) error { _, err := fmt.Fprint(wout, flagRepeat); return err })
+
+	c.New("empty", "empty subcommand")
+	c.New("hidden", command.UsageInternal)
+
+	c.New("join", "wraps strings.Join").
+		Command("out", "write result to wout", func(args []string) error {
+			if len(args) == 0 {
+				return errJoinLen
+			}
+			_, err := fmt.Fprint(wout, strings.Join(args[:len(args)-1], args[len(args)-1]))
+			return err
+		}).
+		Command("log", "log result to wlog", func(args []string) error {
+			if len(args) == 0 {
+				return errJoinLen
+			}
+			logf("%s", strings.Join(args[:len(args)-1], args[len(args)-1]))
+			return nil
+		})
+
+	c.Command("succeed", "this command succeeds", func([]string) error { return nil })
+
+	c.New("deep", "top level of command tree with various levels").
+		New("d=2", "relative second level").
+		New("d=3", "relative third level").
+		New("d=4", "relative fourth level")
+
+	return
+}
+
+func newLogFunc(w io.Writer) command.LogFunc { return log.New(w, "test: ", 0).Printf }

command/unreachable_test.go

@@ -0,0 +1,54 @@
+package command
+
+import (
+	"flag"
+	"testing"
+)
+
+func TestParseUnreachable(t *testing.T) {
+	// top level bypasses name matching and recursive calls to Parse
+	// returns when encountering zero-length args
+	t.Run("zero-length args", func(t *testing.T) {
+		defer checkRecover(t, "Parse", "attempted to parse with zero length args")
+		_ = newNode(panicWriter{}, nil, " ", " ").Parse(nil)
+	})
+
+	// top level must not have siblings
+	t.Run("toplevel siblings", func(t *testing.T) {
+		defer checkRecover(t, "Parse", "invalid toplevel state")
+		n := newNode(panicWriter{}, nil, " ", "")
+		n.append(newNode(panicWriter{}, nil, "  ", " "))
+		_ = n.Parse(nil)
+	})
+
+	// a node with descendents must not have a direct handler
+	t.Run("sub handle conflict", func(t *testing.T) {
+		defer checkRecover(t, "Parse", "invalid subcommand tree state")
+		n := newNode(panicWriter{}, nil, " ", " ")
+		n.adopt(newNode(panicWriter{}, nil, " ", " "))
+		n.f = func([]string) error { panic("unreachable") }
+		_ = n.Parse([]string{" "})
+	})
+
+	// this would only happen if a node was matched twice
+	t.Run("parsed flag set", func(t *testing.T) {
+		defer checkRecover(t, "Parse", "invalid set state")
+		n := newNode(panicWriter{}, nil, " ", "")
+		set := flag.NewFlagSet("parsed", flag.ContinueOnError)
+		set.SetOutput(panicWriter{})
+		_ = set.Parse(nil)
+		n.set = set
+		_ = n.Parse(nil)
+	})
+}
+
+type panicWriter struct{}
+
+func (p panicWriter) Write([]byte) (int, error) { panic("unreachable") }
+
+func checkRecover(t *testing.T, name, wantPanic string) {
+	if r := recover(); r != wantPanic {
+		t.Errorf("%s: panic = %v; wantPanic %v",
+			name, r, wantPanic)
+	}
+}

command/wrap.go

@@ -0,0 +1,14 @@
+package command
+
+// the top level node wants [Command] returned for its builder methods
+type rootNode struct{ *node }
+
+func (r rootNode) Command(name, usage string, f HandlerFunc) Command {
+	r.node.Command(name, usage, f)
+	return r
+}
+
+func (r rootNode) Flag(p any, name string, value FlagDefiner, usage string) Command {
+	r.node.Flag(p, name, value, usage)
+	return r
+}

dbus/dbus_test.go

@@ -1,14 +1,22 @@
 package dbus_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"fmt"
+	"os"
+	"os/exec"
 	"strings"
+	"syscall"
 	"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) {
@@ -64,7 +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)
@@ -100,15 +108,20 @@ 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 +138,33 @@ 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 +173,16 @@ 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 +200,7 @@ 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 +208,20 @@ 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 +229,7 @@ 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 +242,10 @@ 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, 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() }

dist/release.sh

@@ -10,9 +10,10 @@ cp -rv "comp" "${out}"
 
 go generate ./...
 go build -trimpath -v -o "${out}/bin/" -ldflags "-s -w -buildid= -extldflags '-static'
-  -X git.gensokyo.uk/security/fortify/internal.Version=${VERSION}
-  -X git.gensokyo.uk/security/fortify/internal.Fsu=/usr/bin/fsu
-  -X main.Fmain=/usr/bin/fortify" ./...
+  -X git.gensokyo.uk/security/fortify/internal.version=${VERSION}
+  -X git.gensokyo.uk/security/fortify/internal.fsu=/usr/bin/fsu
+  -X main.fmain=/usr/bin/fortify
+  -X main.fpkg=/usr/bin/fpkg" ./...
 
 rm -f "./${out}.tar.gz" && tar -C dist -czf "${out}.tar.gz" "${pname}"
 rm -rf "./${out}"

error.go

@@ -1,55 +0,0 @@
-package main
-
-import (
-	"errors"
-
-	"git.gensokyo.uk/security/fortify/internal/app"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-func logWaitError(err error) {
-	var e *fmsg.BaseError
-	if !fmsg.AsBaseError(err, &e) {
-		fmsg.Println("wait failed:", err)
-	} else {
-		// Wait only returns either *app.ProcessError or *app.StateStoreError wrapped in a *app.BaseError
-		var se *app.StateStoreError
-		if !errors.As(err, &se) {
-			// does not need special handling
-			fmsg.Print(e.Message())
-		} else {
-			// inner error are either unwrapped store errors
-			// or joined errors returned by *appSealTx revert
-			// wrapped in *app.BaseError
-			var ej app.RevertCompoundError
-			if !errors.As(se.InnerErr, &ej) {
-				// does not require special handling
-				fmsg.Print(e.Message())
-			} else {
-				errs := ej.Unwrap()
-
-				// every error here is wrapped in *app.BaseError
-				for _, ei := range errs {
-					var eb *fmsg.BaseError
-					if !errors.As(ei, &eb) {
-						// unreachable
-						fmsg.Println("invalid error type returned by revert:", ei)
-					} else {
-						// print inner *app.BaseError message
-						fmsg.Print(eb.Message())
-					}
-				}
-			}
-		}
-	}
-}
-
-func logBaseError(err error, message string) {
-	var e *fmsg.BaseError
-
-	if fmsg.AsBaseError(err, &e) {
-		fmsg.Print(e.Message())
-	} else {
-		fmsg.Println(message, err)
-	}
-}

flake.lock

@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1736373539,
-        "narHash": "sha256-dinzAqCjenWDxuy+MqUQq0I4zUSfaCvN9rzuCmgMZJY=",
+        "lastModified": 1742655702,
+        "narHash": "sha256-jbqlw4sPArFtNtA1s3kLg7/A4fzP4GLk9bGbtUJg0JQ=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "bd65bc3cde04c16755955630b344bc9e35272c56",
+        "rev": "0948aeedc296f964140d9429223c7e4a0702a1ff",
         "type": "github"
       },
       "original": {
@@ -23,16 +23,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1739333913,
-        "narHash": "sha256-JXt5FtySR+yBm5ny8zG/hX1IybF/7R66jZfXxXSb6wY=",
+        "lastModified": 1743231893,
+        "narHash": "sha256-tpJsHMUPEhEnzySoQxx7+kA+KUtgWqvlcUBqROYNNt0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "7d83f668aee9e41d574c398a9bb569047e8a3f5d",
+        "rev": "c570c1f5304493cafe133b8d843c7c1c4a10d3a6",
         "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";
@@ -27,12 +27,12 @@
       nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
     in
     {
-      nixosModules.fortify = import ./nixos.nix;
+      nixosModules.fortify = import ./nixos.nix self.packages;
 
       buildPackage = forAllSystems (
         system:
         nixpkgsFor.${system}.callPackage (
-          import ./bundle.nix {
+          import ./cmd/fpkg/build.nix {
             inherit
               nixpkgsFor
               system
@@ -57,18 +57,30 @@
             ;
         in
         {
-          check-formatting =
-            runCommandLocal "check-formatting" { nativeBuildInputs = [ nixfmt-rfc-style ]; }
-              ''
-                cd ${./.}
+          fortify = callPackage ./test { inherit system self; };
+          race = callPackage ./test {
+            inherit system self;
+            withRace = true;
+          };
 
-                echo "running nixfmt..."
-                nixfmt --check .
+          sandbox = callPackage ./test/sandbox { inherit self; };
+          sandbox-race = callPackage ./test/sandbox {
+            inherit self;
+            withRace = true;
+          };
 
-                touch $out
-              '';
+          fpkg = callPackage ./cmd/fpkg/test { inherit system self; };
 
-          check-lint =
+          formatting = runCommandLocal "check-formatting" { nativeBuildInputs = [ nixfmt-rfc-style ]; } ''
+            cd ${./.}
+
+            echo "running nixfmt..."
+            nixfmt --width=256 --check .
+
+            touch $out
+          '';
+
+          lint =
             runCommandLocal "check-lint"
               {
                 nativeBuildInputs = [
@@ -87,120 +99,68 @@
 
                 touch $out
               '';
-
-          nixos-tests = callPackage ./test.nix { inherit system self home-manager; };
         }
       );
 
       packages = forAllSystems (
         system:
         let
-          inherit (self.packages.${system}) fortify;
+          inherit (self.packages.${system}) fortify fsu;
           pkgs = nixpkgsFor.${system};
         in
         {
-          default = self.packages.${system}.fortify;
-          fortify = pkgs.callPackage ./package.nix { };
+          default = fortify;
+          fortify = pkgs.pkgsStatic.callPackage ./package.nix {
+            inherit (pkgs)
+              # passthru.buildInputs
+              go
+              gcc
 
-          dist =
-            pkgs.runCommand "${fortify.name}-dist" { inherit (self.devShells.${system}.default) buildInputs; }
-              ''
-                # go requires XDG_CACHE_HOME for the build cache
-                export XDG_CACHE_HOME="$(mktemp -d)"
+              # nativeBuildInputs
+              pkg-config
+              wayland-scanner
+              makeBinaryWrapper
 
-                # get a different workdir as go does not like /build
-                cd $(mktemp -d) && cp -r ${fortify.src}/. . && chmod -R +w .
+              # appPackages
+              glibc
+              xdg-dbus-proxy
 
-                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"
-            '';
+              # fpkg
+              zstd
+              gnutar
+              coreutils
+              ;
           };
+          fsu = pkgs.callPackage ./cmd/fsu/package.nix { inherit (self.packages.${system}) fortify; };
+
+          dist = pkgs.runCommand "${fortify.name}-dist" { buildInputs = fortify.targetPkgs ++ [ pkgs.pkgsStatic.musl ]; } ''
+            # go requires XDG_CACHE_HOME for the build cache
+            export XDG_CACHE_HOME="$(mktemp -d)"
+
+            # get a different workdir as go does not like /build
+            cd $(mktemp -d) \
+                && cp -r ${fortify.src}/. . \
+                && chmod +w cmd && cp -r ${fsu.src}/. cmd/fsu/ \
+                && chmod -R +w .
+
+            export FORTIFY_VERSION="v${fortify.version}"
+            ./dist/release.sh && mkdir $out && cp -v "dist/fortify-$FORTIFY_VERSION.tar.gz"* $out
+          '';
         }
       );
 
       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 =
@@ -209,7 +169,7 @@
                     specialArgs = {
                       inherit pkgs;
                     };
-                    modules = [ ./options.nix ];
+                    modules = [ (import ./options.nix self.packages) ];
                   };
                   cleanEval = lib.filterAttrsRecursive (n: _: n != "_module") eval;
                 in
@@ -219,7 +179,7 @@
                 sed -i '/*Declared by:*/,+1 d' $out
               '';
             in
-            nixpkgsFor.${system}.mkShell {
+            pkgs.mkShell {
               shellHook = ''
                 exec cat ${docText} > options.md
               '';

fst/app.go

@@ -0,0 +1,47 @@
+// Package fst exports shared fortify types.
+package fst
+
+import (
+	"time"
+)
+
+type App interface {
+	// ID returns a copy of [fst.ID] held by App.
+	ID() ID
+
+	// Seal determines the outcome of config as a [SealedApp].
+	// The value of config might be overwritten and must not be used again.
+	Seal(config *Config) (SealedApp, error)
+
+	String() string
+}
+
+type SealedApp interface {
+	// Run commits sealed system setup and starts the app process.
+	Run(rs *RunState) error
+}
+
+// RunState stores the outcome of a call to [SealedApp.Run].
+type RunState struct {
+	// Time is the exact point in time where the process was created.
+	// Location must be set to UTC.
+	//
+	// Time is nil if no process was ever created.
+	Time *time.Time
+	// ExitCode is the value returned by shim.
+	ExitCode int
+	// RevertErr is stored by the deferred revert call.
+	RevertErr error
+	// WaitErr is error returned by the underlying wait syscall.
+	WaitErr error
+}
+
+// Paths contains environment-dependent paths used by fortify.
+type Paths struct {
+	// path to shared directory (usually `/tmp/fortify.%d`)
+	SharePath string `json:"share_path"`
+	// XDG_RUNTIME_DIR value (usually `/run/user/%d`)
+	RuntimePath string `json:"runtime_path"`
+	// application runtime directory (usually `/run/user/%d/fortify`)
+	RunDirPath string `json:"run_dir_path"`
+}

fst/config.go

@@ -2,18 +2,23 @@ package fst
 
 import (
 	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/system"
+	"git.gensokyo.uk/security/fortify/sandbox/seccomp"
+	"git.gensokyo.uk/security/fortify/system"
 )
 
 const Tmp = "/.fortify"
 
 // Config is used to seal an app
 type Config struct {
-	// application ID
+	// reverse-DNS style arbitrary identifier string from config;
+	// passed to wayland security-context-v1 as application ID
+	// and used as part of defaults in dbus session proxy
 	ID string `json:"id"`
-	// value passed through to the child process as its argv
-	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"`
 }
@@ -24,15 +29,17 @@ 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
+	// absolute path to shell, empty for host shell
+	Shell string `json:"shell,omitempty"`
+	// abstract sandbox configuration
 	Sandbox *SandboxConfig `json:"sandbox"`
-	// extra acl entries to append
+	// extra acl ops, runs after everything else
 	ExtraPerms []*ExtraPermConfig `json:"extra_perms,omitempty"`
 
 	// reference to a system D-Bus proxy configuration,
@@ -42,8 +49,8 @@ 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 {
@@ -74,24 +81,12 @@ 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",
@@ -104,13 +99,16 @@ 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",
-				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
@@ -129,10 +127,10 @@ 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},
@@ -158,7 +156,7 @@ 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

@@ -4,111 +4,153 @@ 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/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/linux"
+	"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
-	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"`
-	// paths to override by mounting tmpfs over them
-	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"`
 
-// 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(os linux.System) (*bwrap.Config, 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"`
+
+		// 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"`
+
+		// 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 {
-		fmsg.VPrintln("syscall filter not configured, PROCEED WITH CAUTION")
-	}
-
-	var uid int
-	if !s.MapRealUID {
-		uid = 65534
-	} else {
-		uid = os.Geteuid()
-	}
-
-	conf := (&bwrap.Config{
-		Net:      s.Net,
-		UserNS:   s.UserNS,
+	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),
+	if s.Multiarch {
+		container.Seccomp |= seccomp.FlagMultiarch
+	}
 
-		Syscall:       s.Syscall,
-		NewSession:    !s.NoNewSession,
-		DieWithParent: true,
-		AsInit:        true,
+	/* 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)
 
-		// initialise unconditionally as Once cannot be justified
-		// for saving such a miniscule amount of memory
-		Chmod: make(bwrap.ChmodConfig),
-	}).
-		SetUID(uid).SetGID(uid).
-		Procfs("/proc").
-		Tmpfs(Tmp, 4*1024)
+	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
+	}
+
+	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 := os.Paths()
+	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 {
@@ -121,11 +163,11 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
 						// get parent dir of socket
 						dir := path.Dir(pair[1])
 						if dir == "." || dir == "/" {
-							fmsg.VPrintf("dbus socket %q is in an unusual location", pair[1])
+							sys.Printf("dbus socket %q is in an unusual location", pair[1])
 						}
 						hidePaths = append(hidePaths, dir)
 					} else {
-						fmsg.VPrintf("dbus socket %q is not absolute", pair[1])
+						sys.Printf("dbus socket %q is not absolute", pair[1])
 					}
 				}
 			}
@@ -133,8 +175,8 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
 	}
 	hidePathMatch := make([]bool, len(hidePaths))
 	for i := range hidePaths {
-		if err := evalSymlinks(os, &hidePaths[i]); err != nil {
-			return nil, err
+		if err := evalSymlinks(sys, &hidePaths[i]); err != nil {
+			return nil, nil, err
 		}
 	}
 
@@ -144,19 +186,19 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*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(os, &srcH); err != nil {
-			return nil, err
+		if err := evalSymlinks(sys, &srcH); err != nil {
+			return nil, nil, err
 		}
 
 		for i := range hidePaths {
@@ -166,62 +208,77 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*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
-				fmsg.VPrintf("hiding paths from %q", c.Src)
+				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 := os.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(os linux.System, v *string) error {
-	if p, err := os.EvalSymlinks(*v); err != nil {
+func evalSymlinks(sys SandboxSys, v *string) error {
+	if p, err := sys.EvalSymlinks(*v); err != nil {
 		if !errors.Is(err, fs.ErrNotExist) {
 			return err
 		}
-		fmsg.VPrintf("path %q does not yet exist", *v)
+		sys.Printf("path %q does not yet exist", *v)
 	} else {
 		*v = p
 	}

fst/shared.go

@@ -1,2 +0,0 @@
-// Package fst exports shared fortify types.
-package fst

go.mod

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

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/bwrap.go

@@ -1,87 +0,0 @@
-package helper
-
-import (
-	"context"
-	"errors"
-	"io"
-	"os"
-	"slices"
-	"strconv"
-	"sync"
-
-	"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
-
-	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)
-	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,
-	wt io.WriterTo, argF func(argsFD, statFD int) []string,
-	extraFiles []*os.File,
-	syncFd *os.File,
-) Helper {
-	b, err := NewBwrap(conf, name, 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,
-	wt io.WriterTo, argF func(argsFd, statFd int) []string,
-	extraFiles []*os.File,
-	syncFd *os.File,
-) (Helper, error) {
-	b := new(bubblewrap)
-
-	b.name = name
-	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

@@ -1,188 +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
-	}
-}
-
-// Write copy from FD to destination DEST
-// (--file FD DEST)
-func (c *Config) Write(dest string, payload []byte) *Config {
-	c.Filesystem = append(c.Filesystem, &DataConfig{Dest: dest, Data: payload, 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 {
-	t := DataROBind
-	if len(opts) > 0 && opts[0] {
-		t = DataBind
-	}
-	c.Filesystem = append(c.Filesystem, &DataConfig{Dest: dest, Data: payload, Type: t})
-	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 (
-	"os"
-	"slices"
-	"testing"
-
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/helper/seccomp"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-func TestConfig_Args(t *testing.T) {
-	seccomp.CPrintln = fmsg.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)).
-				Write("/.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

@@ -1,103 +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",
-			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",
-			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",
-			nil, argF,
-			nil, nil,
-		)
-	})
-
-	t.Run("start without pipes", func(t *testing.T) {
-		helper.InternalReplaceExecCommand(t)
-
-		h := helper.MustNewBwrap(
-			sc, "crash-test-dummy",
-			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", 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 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
+	"os"
 	"strconv"
 	"strings"
 	"testing"
@@ -35,7 +37,8 @@ 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 +49,15 @@ 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()
-
-		stdout, stderr := new(strings.Builder), new(strings.Builder)
-		h.Stdout(stdout).Stderr(stderr)
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		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() {
@@ -65,10 +69,8 @@ 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 +79,8 @@ 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
@@ -87,8 +89,8 @@ func testHelper(t *testing.T, createHelper func() helper.Helper) {
 
 		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) {
@@ -100,34 +102,36 @@ 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 := trimStdout(stdout); got != wantPayload {
+			t.Errorf("Start: stdout = %q, want %q",
 				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 := new(strings.Builder)
+		h := createHelper(ctx, func(stdoutP, stderrP *io.Writer) { *stdoutP, *stderrP = stdout, os.Stderr }, false)
 
-		if err := h.Start(ctx, false); err != nil {
-			t.Errorf("Start() error = %v",
+		if err := h.Start(); err != nil {
+			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 := stdout.String(); !strings.HasPrefix(got, wantPayload) {
-			t.Errorf("Start() stdout = %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/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/proc/pipe.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"os"
+	"runtime"
 )
 
 // NewWriterTo returns a [File] that receives content from wt on fulfillment.
@@ -25,13 +26,20 @@ func (f *writeToFile) Fulfill(ctx context.Context, dispatchErr func(error)) erro
 	f.Set(r)
 
 	done := make(chan struct{})
-	go func() { _, err = f.wt.WriteTo(w); dispatchErr(err); dispatchErr(w.Close()); close(done) }()
+	go func() {
+		_, err = f.wt.WriteTo(w)
+		dispatchErr(err)
+		dispatchErr(w.Close())
+		close(done)
+		runtime.KeepAlive(r)
+	}()
 	go func() {
 		select {
 		case <-done:
 			dispatchErr(nil)
 		case <-ctx.Done():
 			dispatchErr(w.Close()) // this aborts WriteTo with file already closed
+			runtime.KeepAlive(r)
 		}
 	}()
 
@@ -83,6 +91,7 @@ func (f *statFile) Fulfill(ctx context.Context, dispatchErr func(error)) error {
 		default:
 			panic("unreachable")
 		}
+		runtime.KeepAlive(w)
 	}()
 
 	go func() {
@@ -91,6 +100,7 @@ func (f *statFile) Fulfill(ctx context.Context, dispatchErr func(error)) error {
 			dispatchErr(nil)
 		case <-ctx.Done():
 			dispatchErr(r.Close()) // this aborts Read with file already closed
+			runtime.KeepAlive(w)
 		}
 	}()
 

helper/seccomp/seccomp.go

@@ -1,88 +0,0 @@
-package seccomp
-
-/*
-#cgo linux pkg-config: --static libseccomp
-
-#include "seccomp-export.h"
-*/
-import "C"
-import (
-	"errors"
-	"fmt"
-	"runtime"
-)
-
-var CPrintln func(v ...any)
-
-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"),
-}
-
-type SyscallOpts = C.f_syscall_opts
-
-const (
-	flagVerbose SyscallOpts = C.F_VERBOSE
-	// FlagExt are project-specific extensions.
-	FlagExt SyscallOpts = C.F_EXT
-	// FlagDenyNS denies namespace setup syscalls.
-	FlagDenyNS SyscallOpts = C.F_DENY_NS
-	// FlagDenyTTY denies faking input.
-	FlagDenyTTY SyscallOpts = C.F_DENY_TTY
-	// FlagDenyDevel denies development-related syscalls.
-	FlagDenyDevel SyscallOpts = C.F_DENY_DEVEL
-	// FlagMultiarch allows multiarch/emulation.
-	FlagMultiarch SyscallOpts = C.F_MULTIARCH
-	// FlagLinux32 sets PER_LINUX32.
-	FlagLinux32 SyscallOpts = C.F_LINUX32
-	// FlagCan allows AF_CAN.
-	FlagCan SyscallOpts = C.F_CAN
-	// FlagBluetooth allows AF_BLUETOOTH.
-	FlagBluetooth SyscallOpts = C.F_BLUETOOTH
-)
-
-func exportFilter(fd uintptr, opts SyscallOpts) error {
-	var (
-		arch      C.uint32_t = 0
-		multiarch C.uint32_t = 0
-	)
-	switch runtime.GOARCH {
-	case "386":
-		arch = C.SCMP_ARCH_X86
-	case "amd64":
-		arch = C.SCMP_ARCH_X86_64
-		multiarch = C.SCMP_ARCH_X86
-	case "arm":
-		arch = C.SCMP_ARCH_ARM
-	case "arm64":
-		arch = C.SCMP_ARCH_AARCH64
-		multiarch = C.SCMP_ARCH_ARM
-	}
-
-	// this removes repeated transitions between C and Go execution
-	// when producing log output via F_println and CPrintln is nil
-	if CPrintln != 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
-		}
-		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))
-	}
-}

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/fmsg"
 )
 
-// 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))
 
-	fmsg.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 {
@@ -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

@@ -2,71 +2,81 @@ package app
 
 import (
 	"context"
+	"fmt"
+	"log"
 	"sync"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal/linux"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal/sys"
 )
 
-type App interface {
-	// ID returns a copy of App's unique ID.
-	ID() fst.ID
-	// Run sets up the system and runs the App.
-	Run(ctx context.Context, rs *RunState) error
+func New(ctx context.Context, os sys.State) (fst.App, error) {
+	a := new(app)
+	a.sys = os
+	a.ctx = ctx
 
-	Seal(config *fst.Config) error
-	String() string
+	id := new(fst.ID)
+	err := fst.NewAppID(id)
+	a.id = newID(id)
+
+	return a, err
 }
 
-type RunState struct {
-	// Start is true if fsu is successfully started.
-	Start bool
-	// ExitCode is the value returned by shim.
-	ExitCode int
-	// WaitErr is error returned by the underlying wait syscall.
-	WaitErr error
+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)
+	}
+	return a
 }
 
 type app struct {
-	// application unique identifier
-	id *fst.ID
-	// operating system interface
-	os linux.System
-	// shim process manager
-	shim *shim.Shim
-	// child process related information
-	seal *appSeal
+	id  *stringPair[fst.ID]
+	sys sys.State
+	ctx context.Context
 
-	lock sync.RWMutex
+	*outcome
+	mu sync.RWMutex
 }
 
-func (a *app) ID() fst.ID {
-	return *a.id
-}
+func (a *app) ID() fst.ID { a.mu.RLock(); defer a.mu.RUnlock(); return a.id.unwrap() }
 
 func (a *app) String() string {
 	if a == nil {
-		return "(invalid fortified app)"
+		return "(invalid app)"
 	}
 
-	a.lock.RLock()
-	defer a.lock.RUnlock()
+	a.mu.RLock()
+	defer a.mu.RUnlock()
 
-	if a.shim != nil {
-		return a.shim.String()
+	if a.outcome != nil {
+		if a.outcome.user.uid == nil {
+			return fmt.Sprintf("(sealed app %s with invalid uid)", a.id)
+		}
+		return fmt.Sprintf("(sealed app %s as uid %s)", a.id, a.outcome.user.uid)
 	}
 
-	if a.seal != nil {
-		return "(sealed fortified app as uid " + a.seal.sys.user.us + ")"
-	}
-
-	return "(unsealed fortified app)"
+	return fmt.Sprintf("(unsealed app %s)", a.id)
 }
 
-func New(os linux.System) (App, error) {
-	a := new(app)
-	a.id = new(fst.ID)
-	a.os = os
-	return a, fst.NewAppID(a.id)
+func (a *app) Seal(config *fst.Config) (fst.SealedApp, error) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	if a.outcome != nil {
+		panic("app sealed twice")
+	}
+	if config == nil {
+		return nil, fmsg.WrapError(ErrConfig,
+			"attempted to seal app with nil config")
+	}
+
+	seal := new(outcome)
+	seal.id = a.id
+	err := seal.finalise(a.ctx, a.sys, config)
+	if err == nil {
+		a.outcome = seal
+	}
+	return seal, err
 }

internal/app/app_nixos_test.go

@@ -4,28 +4,28 @@ 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/internal/system"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/system"
 )
 
 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,
+					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},
-					}, AutoEtc: 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{
@@ -56,15 +56,15 @@ var testCasesNixos = []sealTestCase{
 		},
 		system.New(1000001).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ephemeral(system.Process, "/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1", 0711).
 			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
-			Ephemeral(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/8e2c76b066dabe574cf073bdb46eb5c1", acl.Execute).
 			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("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/pulse-cookie", "/home/ophestra/xdg/config/pulse/cookie").
+			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",
@@ -88,136 +88,133 @@ 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",
+				"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",
 			},
-			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").
-			Bind("/tmp/fortify.1971/tmpdir/1", "/tmp", false, true).
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/1971", 8388608).
-			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").
-			Bind("/tmp/fortify.1971/8e2c76b066dabe574cf073bdb46eb5c1/pulse-cookie", fst.Tmp+"/pulse-cookie").
-			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

@@ -1,18 +1,19 @@
 package app_test
 
 import (
+	"os"
+
 	"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/system"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/system"
 )
 
 var testCasesPd = []sealTestCase{
 	{
 		"nixos permissive defaults no enablements", new(stubNixOS),
 		&fst.Config{
-			Command: make([]string, 0),
 			Confinement: fst.ConfinementConfig{
 				AppID:    0,
 				Username: "chronos",
@@ -27,142 +28,134 @@ var testCasesPd = []sealTestCase{
 		},
 		system.New(1000000).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ephemeral(system.Process, "/tmp/fortify.1971/4a450b6596d7bc15bd01780eb9a607ac", 0711).
 			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).
-			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/4a450b6596d7bc15bd01780eb9a607ac", 0700).UpdatePermType(system.Process, "/run/user/1971/fortify/4a450b6596d7bc15bd01780eb9a607ac", 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").
-			Bind("/tmp/fortify.1971/tmpdir/0", "/tmp", false, true).
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/65534", 8388608).
-			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"),
+			Ensure("/tmp/fortify.1971/tmpdir/0", 01700).UpdatePermType(system.User, "/tmp/fortify.1971/tmpdir/0", acl.Read, acl.Write, acl.Execute),
+		&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",
+				"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",
+			},
+			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"},
@@ -199,7 +192,7 @@ var testCasesPd = []sealTestCase{
 					},
 					Filter: true,
 				},
-				Enablements: system.EWayland.Mask() | system.EDBus.Mask() | system.EPulse.Mask(),
+				Enablements: system.EWayland | system.EDBus | system.EPulse,
 			},
 		},
 		fst.ID{
@@ -210,16 +203,15 @@ var testCasesPd = []sealTestCase{
 		},
 		system.New(1000009).
 			Ensure("/tmp/fortify.1971", 0711).
-			Ephemeral(system.Process, "/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c", 0711).
 			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).
+			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).
-			Ensure("/tmp/fortify.1971/wayland", 0711).
-			Wayland("/tmp/fortify.1971/wayland/ebf083d1b175911782d413369b64ce7c", "/run/user/1971/wayland-0", "org.chromium.Chromium", "ebf083d1b175911782d413369b64ce7c").
 			Link("/run/user/1971/pulse/native", "/run/user/1971/fortify/ebf083d1b175911782d413369b64ce7c/pulse").
-			CopyFile("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/pulse-cookie", "/home/ophestra/xdg/config/pulse/cookie").
+			CopyFile(new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 256, 256).
 			MustProxyDBus("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/bus", &dbus.Config{
 				Talk: []string{
 					"org.freedesktop.Notifications",
@@ -252,141 +244,136 @@ 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",
+				"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",
 			},
-			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").
-			Bind("/tmp/fortify.1971/tmpdir/9", "/tmp", false, true).
-			Tmpfs("/run/user", 1048576).
-			Tmpfs("/run/user/65534", 8388608).
-			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").
-			Bind("/tmp/fortify.1971/ebf083d1b175911782d413369b64ce7c/pulse-cookie", fst.Tmp+"/pulse-cookie").
-			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/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).
+				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

@@ -3,10 +3,11 @@ package app_test
 import (
 	"fmt"
 	"io/fs"
+	"log"
 	"os/user"
 	"strconv"
 
-	"git.gensokyo.uk/security/fortify/internal/linux"
+	"git.gensokyo.uk/security/fortify/fst"
 )
 
 // fs methods are not implemented using a real FS
@@ -16,13 +17,17 @@ 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)) }
 func (s *stubNixOS) EvalSymlinks(path string) (string, error) { return path, nil }
 func (s *stubNixOS) Uid(aid int) (int, error)                 { return 1000000 + 0*10000 + aid, nil }
 
+func (s *stubNixOS) Println(v ...any)               { log.Println(v...) }
+func (s *stubNixOS) Printf(format string, v ...any) { log.Printf(format, v...) }
+
 func (s *stubNixOS) LookupEnv(key string) (string, bool) {
 	switch key {
 	case "SHELL":
@@ -50,10 +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))
 	}
@@ -122,8 +125,8 @@ func (s *stubNixOS) Open(name string) (fs.File, error) {
 	}
 }
 
-func (s *stubNixOS) Paths() linux.Paths {
-	return linux.Paths{
+func (s *stubNixOS) Paths() fst.Paths {
+	return fst.Paths{
 		SharePath:   "/tmp/fortify.1971",
 		RuntimePath: "/run/user/1971",
 		RunDirPath:  "/run/user/1971/fortify",

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/linux"
-	"git.gensokyo.uk/security/fortify/internal/system"
+	"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        linux.System
-	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) {
@@ -29,17 +29,21 @@ func TestApp(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			a := app.NewWithID(tc.id, tc.os)
-
+			var (
+				gotSys       *system.I
+				gotContainer *sandbox.Params
+			)
 			if !t.Run("seal", func(t *testing.T) {
-				if err := a.Seal(tc.config); err != nil {
+				if sa, err := a.Seal(tc.config); err != nil {
 					t.Errorf("Seal: error = %v", err)
+					return
+				} else {
+					gotSys, gotContainer = app.AppIParams(a, sa)
 				}
 			}) {
 				return
 			}
 
-			gotSys, gotBwrap := app.AppSystemBwrap(a)
-
 			t.Run("compare sys", func(t *testing.T) {
 				if !gotSys.Equal(tc.wantSys) {
 					t.Errorf("Seal: sys = %#v, want %#v",
@@ -47,10 +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/errors.go

@@ -0,0 +1,179 @@
+package app
+
+import (
+	"errors"
+	"log"
+
+	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+)
+
+func PrintRunStateErr(rs *fst.RunState, runErr error) {
+	if runErr != nil {
+		if rs.Time == nil {
+			fmsg.PrintBaseError(runErr, "cannot start app:")
+		} else {
+			var e *fmsg.BaseError
+			if !fmsg.AsBaseError(runErr, &e) {
+				log.Println("wait failed:", runErr)
+			} else {
+				// Wait only returns either *app.ProcessError or *app.StateStoreError wrapped in a *app.BaseError
+				var se *StateStoreError
+				if !errors.As(runErr, &se) {
+					// does not need special handling
+					log.Print(e.Message())
+				} else {
+					// inner error are either unwrapped store errors
+					// or joined errors returned by *appSealTx revert
+					// wrapped in *app.BaseError
+					var ej RevertCompoundError
+					if !errors.As(se.InnerErr, &ej) {
+						// does not require special handling
+						log.Print(e.Message())
+					} else {
+						errs := ej.Unwrap()
+
+						// every error here is wrapped in *app.BaseError
+						for _, ei := range errs {
+							var eb *fmsg.BaseError
+							if !errors.As(ei, &eb) {
+								// unreachable
+								log.Println("invalid error type returned by revert:", ei)
+							} else {
+								// print inner *app.BaseError message
+								log.Print(eb.Message())
+							}
+						}
+					}
+				}
+			}
+		}
+
+		if rs.ExitCode == 0 {
+			rs.ExitCode = 126
+		}
+	}
+
+	if rs.RevertErr != nil {
+		var stateStoreError *StateStoreError
+		if !errors.As(rs.RevertErr, &stateStoreError) || stateStoreError == nil {
+			fmsg.PrintBaseError(rs.RevertErr, "generic fault during cleanup:")
+			goto out
+		}
+
+		if stateStoreError.Err != nil {
+			if len(stateStoreError.Err) == 2 {
+				if stateStoreError.Err[0] != nil {
+					if joinedErrs, ok := stateStoreError.Err[0].(interface{ Unwrap() []error }); !ok {
+						fmsg.PrintBaseError(stateStoreError.Err[0], "generic fault during revert:")
+					} else {
+						for _, err := range joinedErrs.Unwrap() {
+							if err != nil {
+								fmsg.PrintBaseError(err, "fault during revert:")
+							}
+						}
+					}
+				}
+				if stateStoreError.Err[1] != nil {
+					log.Printf("cannot close store: %v", stateStoreError.Err[1])
+				}
+			} else {
+				log.Printf("fault during cleanup: %v",
+					errors.Join(stateStoreError.Err...))
+			}
+		}
+
+		if stateStoreError.OpErr != nil {
+			log.Printf("blind revert due to store fault: %v",
+				stateStoreError.OpErr)
+		}
+
+		if stateStoreError.DoErr != nil {
+			fmsg.PrintBaseError(stateStoreError.DoErr, "state store operation unsuccessful:")
+		}
+
+		if stateStoreError.Inner && stateStoreError.InnerErr != nil {
+			fmsg.PrintBaseError(stateStoreError.InnerErr, "cannot destroy state entry:")
+		}
+
+	out:
+		if rs.ExitCode == 0 {
+			rs.ExitCode = 128
+		}
+	}
+	if rs.WaitErr != nil {
+		log.Println("inner wait failed:", rs.WaitErr)
+	}
+}
+
+// StateStoreError is returned for a failed state save
+type StateStoreError struct {
+	// whether inner function was called
+	Inner bool
+	// returned by the Save/Destroy method of [state.Cursor]
+	InnerErr error
+	// returned by the Do method of [state.Store]
+	DoErr error
+	// stores an arbitrary store operation error
+	OpErr error
+	// stores arbitrary errors
+	Err []error
+}
+
+// save saves arbitrary errors in [StateStoreError] once.
+func (e *StateStoreError) save(errs []error) {
+	if len(errs) == 0 || e.Err != nil {
+		panic("invalid call to save")
+	}
+	e.Err = errs
+}
+
+func (e *StateStoreError) equiv(a ...any) error {
+	if e.Inner && e.InnerErr == nil && e.DoErr == nil && e.OpErr == nil && errors.Join(e.Err...) == nil {
+		return nil
+	} else {
+		return fmsg.WrapErrorSuffix(e, a...)
+	}
+}
+
+func (e *StateStoreError) Error() string {
+	if e.Inner && e.InnerErr != nil {
+		return e.InnerErr.Error()
+	}
+	if e.DoErr != nil {
+		return e.DoErr.Error()
+	}
+	if e.OpErr != nil {
+		return e.OpErr.Error()
+	}
+	if err := errors.Join(e.Err...); err != nil {
+		return err.Error()
+	}
+
+	// equiv nullifies e for values where this is reached
+	panic("unreachable")
+}
+
+func (e *StateStoreError) Unwrap() (errs []error) {
+	errs = make([]error, 0, 3)
+	if e.InnerErr != nil {
+		errs = append(errs, e.InnerErr)
+	}
+	if e.DoErr != nil {
+		errs = append(errs, e.DoErr)
+	}
+	if e.OpErr != nil {
+		errs = append(errs, e.OpErr)
+	}
+	if err := errors.Join(e.Err...); err != nil {
+		errs = append(errs, err)
+	}
+	return
+}
+
+// A RevertCompoundError encapsulates errors returned by
+// the Revert method of [system.I].
+type RevertCompoundError interface {
+	Error() string
+	Unwrap() []error
+}

internal/app/export_test.go

@@ -2,19 +2,23 @@ package app
 
 import (
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/linux"
-	"git.gensokyo.uk/security/fortify/internal/system"
+	"git.gensokyo.uk/security/fortify/internal/sys"
+	"git.gensokyo.uk/security/fortify/sandbox"
+	"git.gensokyo.uk/security/fortify/system"
 )
 
-func NewWithID(id fst.ID, os linux.System) App {
+func NewWithID(id fst.ID, os sys.State) fst.App {
 	a := new(app)
-	a.id = &id
-	a.os = os
+	a.id = newID(&id)
+	a.sys = os
 	return a
 }
 
-func AppSystemBwrap(a App) (*system.I, *bwrap.Config) {
+func AppIParams(a fst.App, sa fst.SealedApp) (*system.I, *sandbox.Params) {
 	v := a.(*app)
-	return v.seal.sys.I, v.seal.sys.bwrap
+	seal := sa.(*outcome)
+	if v.outcome != seal || v.id != seal.id {
+		panic("broken app/outcome link")
+	}
+	return seal.sys, seal.container
 }

internal/app/process.go

@@ -0,0 +1,180 @@
+package app
+
+import (
+	"context"
+	"errors"
+	"log"
+	"os/exec"
+	"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/internal/state"
+	"git.gensokyo.uk/security/fortify/system"
+)
+
+const shimSetupTimeout = 5 * time.Second
+
+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
+		// other Run a chance to return
+		panic("attempted to run twice")
+	}
+
+	if rs == nil {
+		panic("invalid state")
+	}
+
+	// read comp values early to allow for early failure
+	fmsg.Verbosef("version %s", internal.Version())
+	fmsg.Verbosef("setuid helper at %s", internal.MustFsuPath())
+
+	/*
+		prepare/revert os state
+	*/
+
+	if err := seal.sys.Commit(seal.ctx); err != nil {
+		return err
+	}
+	store := state.NewMulti(seal.runDirPath)
+	deferredStoreFunc := func(c state.Cursor) error { return nil }
+	defer func() {
+		var revertErr error
+		storeErr := new(StateStoreError)
+		storeErr.Inner, storeErr.DoErr = store.Do(seal.user.aid.unwrap(), func(c state.Cursor) {
+			revertErr = func() error {
+				storeErr.InnerErr = deferredStoreFunc(c)
+
+				/*
+					revert app setup transaction
+				*/
+
+				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((*system.Criteria)(&ec))
+				} else {
+					if l := len(states); l == 0 {
+						fmsg.Verbose("no other launchers active, will clean up globals")
+						ec |= system.User
+					} else {
+						fmsg.Verbosef("found %d active launchers, cleaning up without globals", l)
+					}
+
+					// accumulate enablements of remaining launchers
+					for i, s := range states {
+						if s.Config != nil {
+							rt |= s.Config.Confinement.Enablements
+						} else {
+							log.Printf("state entry %d does not contain config", i)
+						}
+					}
+				}
+				ec |= rt ^ (system.EWayland | system.EX11 | system.EDBus | system.EPulse)
+				if fmsg.Load() {
+					if ec > 0 {
+						fmsg.Verbose("reverting operations type", system.TypeString(ec))
+					}
+				}
+
+				return seal.sys.Revert((*system.Criteria)(&ec))
+			}()
+		})
+		storeErr.save([]error{revertErr, store.Close()})
+		rs.RevertErr = storeErr.equiv("error returned during cleanup:")
+	}()
+
+	/*
+		shim process lifecycle
+	*/
+
+	waitErr := make(chan error, 1)
+	cmd := new(shimProcess)
+	if startTime, err := cmd.Start(
+		seal.user.aid.String(),
+		seal.user.supp,
+	); err != nil {
+		return err
+	} else {
+		// whether/when the fsu process was created
+		rs.Time = startTime
+	}
+
+	ctx, cancel := context.WithTimeout(seal.ctx, shimSetupTimeout)
+	defer cancel()
+
+	go func() {
+		waitErr <- cmd.Unwrap().Wait()
+		// cancel shim setup in case shim died before receiving payload
+		cancel()
+	}()
+
+	if err := cmd.Serve(ctx, &shimParams{
+		Container: seal.container,
+		Home:      seal.user.data,
+
+		Verbose: fmsg.Load(),
+	}); err != nil {
+		return err
+	}
+
+	// shim accepted setup payload, create process state
+	sd := state.State{
+		ID:   seal.id.unwrap(),
+		PID:  cmd.Unwrap().Process.Pid,
+		Time: *rs.Time,
+	}
+	var earlyStoreErr = new(StateStoreError) // returned after blocking on waitErr
+	earlyStoreErr.Inner, earlyStoreErr.DoErr = store.Do(seal.user.aid.unwrap(), func(c state.Cursor) {
+		earlyStoreErr.InnerErr = c.Save(&sd, seal.ct)
+	})
+	// destroy defunct state entry
+	deferredStoreFunc = func(c state.Cursor) error { return c.Destroy(seal.id.unwrap()) }
+
+	select {
+	case err := <-waitErr: // block until fsu/shim returns
+		if err != nil {
+			var exitError *exec.ExitError
+			if !errors.As(err, &exitError) {
+				// should be unreachable
+				rs.WaitErr = err
+			}
+
+			// store non-zero return code
+			rs.ExitCode = exitError.ExitCode()
+		} else {
+			rs.ExitCode = cmd.Unwrap().ProcessState.ExitCode()
+		}
+		if fmsg.Load() {
+			fmsg.Verbosef("process %d exited with exit code %d", cmd.Unwrap().Process.Pid, rs.ExitCode)
+		}
+
+	// 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.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 <-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 {
+		seal.dbusMsg()
+	}
+
+	return earlyStoreErr.equiv("cannot save process state:")
+}

internal/app/seal.go

@@ -2,24 +2,48 @@ package app
 
 import (
 	"bytes"
+	"context"
 	"encoding/gob"
 	"errors"
 	"fmt"
 	"io"
 	"io/fs"
+	"os"
 	"path"
 	"regexp"
-	"strconv"
+	"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/linux"
-	"git.gensokyo.uk/security/fortify/internal/state"
-	"git.gensokyo.uk/security/fortify/internal/system"
+	"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"
+)
+
+const (
+	home  = "HOME"
+	shell = "SHELL"
+
+	xdgConfigHome   = "XDG_CONFIG_HOME"
+	xdgRuntimeDir   = "XDG_RUNTIME_DIR"
+	xdgSessionClass = "XDG_SESSION_CLASS"
+	xdgSessionType  = "XDG_SESSION_TYPE"
+
+	term    = "TERM"
+	display = "DISPLAY"
+
+	pulseServer = "PULSE_SERVER"
+	pulseCookie = "PULSE_COOKIE"
+
+	dbusSessionBusAddress = "DBUS_SESSION_BUS_ADDRESS"
+	dbusSystemBusAddress  = "DBUS_SYSTEM_BUS_ADDRESS"
 )
 
 var (
@@ -27,182 +51,196 @@ var (
 	ErrUser   = errors.New("invalid aid")
 	ErrHome   = errors.New("invalid home directory")
 	ErrName   = errors.New("invalid username")
+
+	ErrXDisplay = errors.New(display + " unset")
+
+	ErrPulseCookie = errors.New("pulse cookie not present")
+	ErrPulseSocket = errors.New("pulse socket not present")
+	ErrPulseMode   = errors.New("unexpected pulse socket mode")
 )
 
 var posixUsername = regexp.MustCompilePOSIX("^[a-z_]([A-Za-z0-9_-]{0,31}|[A-Za-z0-9_-]{0,30}\\$)$")
 
-// appSeal seals the application with child-related information
-type appSeal struct {
-	// app unique ID string representation
-	id string
+// outcome stores copies of various parts of [fst.Config]
+type outcome struct {
+	// copied from initialising [app]
+	id *stringPair[fst.ID]
+	// copied from [sys.State] response
+	runDirPath string
+
+	// initial [fst.Config] gob stream for state data;
+	// this is prepared ahead of time as config is clobbered during seal creation
+	ct io.WriterTo
 	// dump dbus proxy message buffer
 	dbusMsg func()
 
-	// freedesktop application ID
-	fid string
-	// argv to start process with in the final confined environment
-	command []string
-	// persistent process state store
-	store state.Store
+	user fsuUser
+	sys  *system.I
+	ctx  context.Context
 
-	// process-specific share directory path
-	share string
-	// process-specific share directory path local to XDG_RUNTIME_DIR
-	shareLocal string
+	container *sandbox.Params
+	env       map[string]string
+	sync      *os.File
 
-	// pass-through enablement tracking from config
-	et system.Enablements
-	// initial config gob encoding buffer
-	ct io.WriterTo
-	// wayland socket direct access
-	directWayland bool
-	// extra UpdatePerm ops
-	extraPerms []*sealedExtraPerm
-
-	// prevents sharing from happening twice
-	shared bool
-	// seal system-level component
-	sys *appSealSys
-
-	linux.Paths
-
-	// protected by upstream mutex
+	f atomic.Bool
 }
 
-type sealedExtraPerm struct {
-	name   string
-	perms  acl.Perms
-	ensure 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
 }
 
-// Seal seals the app launch context
-func (a *app) Seal(config *fst.Config) error {
-	a.lock.Lock()
-	defer a.lock.Unlock()
+// 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)
+}
 
-	if a.seal != nil {
-		panic("app sealed twice")
+// 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
+	aid *stringPair[int]
+	// target uid resolved by fid:aid
+	uid *stringPair[int]
+
+	// supplementary group ids
+	supp []string
+
+	// home directory host path
+	data string
+	// app user home directory
+	home string
+	// passwd database username
+	username string
+}
+
+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
+
+	{
+		// encode initial configuration for state tracking
+		ct := new(bytes.Buffer)
+		if err := gob.NewEncoder(ct).Encode(config); err != nil {
+			return fmsg.WrapErrorSuffix(err,
+				"cannot encode initial config:")
+		}
+		seal.ct = ct
 	}
 
-	if config == nil {
-		return fmsg.WrapError(ErrConfig,
-			"attempted to seal app with nil config")
-	}
-
-	// create seal
-	seal := new(appSeal)
-
-	// encode initial configuration for state tracking
-	ct := new(bytes.Buffer)
-	if err := gob.NewEncoder(ct).Encode(config); err != nil {
-		return fmsg.WrapErrorSuffix(err,
-			"cannot encode initial config:")
-	}
-	seal.ct = ct
-
-	// fetch system constants
-	seal.Paths = a.os.Paths()
-
-	// pass through config values
-	seal.id = a.id.String()
-	seal.fid = config.ID
-	seal.command = config.Command
-
-	// create seal system component
-	seal.sys = new(appSealSys)
-
-	// mapped uid
-	if config.Confinement.Sandbox != nil && config.Confinement.Sandbox.MapRealUID {
-		seal.sys.mappedID = a.os.Geteuid()
-	} else {
-		seal.sys.mappedID = 65534
-	}
-	seal.sys.mappedIDString = strconv.Itoa(seal.sys.mappedID)
-	seal.sys.runtime = path.Join("/run/user", seal.sys.mappedIDString)
-
-	// validate uid and set user info
+	// 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,
 			fmt.Sprintf("aid %d out of range", config.Confinement.AppID))
 	}
-	seal.sys.user = appUser{
-		aid:      config.Confinement.AppID,
-		as:       strconv.Itoa(config.Confinement.AppID),
+
+	seal.user = fsuUser{
+		aid:      newInt(config.Confinement.AppID),
 		data:     config.Confinement.Outer,
 		home:     config.Confinement.Inner,
 		username: config.Confinement.Username,
 	}
-	if seal.sys.user.username == "" {
-		seal.sys.user.username = "chronos"
-	} else if !posixUsername.MatchString(seal.sys.user.username) ||
-		len(seal.sys.user.username) >= internal.Sysconf_SC_LOGIN_NAME_MAX() {
+	if seal.user.username == "" {
+		seal.user.username = "chronos"
+	} else if !posixUsername.MatchString(seal.user.username) ||
+		len(seal.user.username) >= internal.Sysconf_SC_LOGIN_NAME_MAX() {
 		return fmsg.WrapError(ErrName,
-			fmt.Sprintf("invalid user name %q", seal.sys.user.username))
+			fmt.Sprintf("invalid user name %q", seal.user.username))
 	}
-	if seal.sys.user.data == "" || !path.IsAbs(seal.sys.user.data) {
+	if seal.user.data == "" || !path.IsAbs(seal.user.data) {
 		return fmsg.WrapError(ErrHome,
-			fmt.Sprintf("invalid home directory %q", seal.sys.user.data))
+			fmt.Sprintf("invalid home directory %q", seal.user.data))
 	}
-	if seal.sys.user.home == "" {
-		seal.sys.user.home = seal.sys.user.data
+	if seal.user.home == "" {
+		seal.user.home = seal.user.data
 	}
-
-	// invoke fsu for full uid
-	if u, err := a.os.Uid(seal.sys.user.aid); err != nil {
-		return fmsg.WrapErrorSuffix(err,
-			"cannot obtain uid from fsu:")
+	if u, err := sys.Uid(seal.user.aid.unwrap()); err != nil {
+		return err
 	} else {
-		seal.sys.user.uid = u
-		seal.sys.user.us = strconv.Itoa(u)
+		seal.user.uid = newInt(u)
 	}
-
-	// resolve supplementary group ids from names
-	seal.sys.user.supp = make([]string, len(config.Confinement.Groups))
+	seal.user.supp = make([]string, len(config.Confinement.Groups))
 	for i, name := range config.Confinement.Groups {
-		if g, err := a.os.LookupGroup(name); err != nil {
+		if g, err := sys.LookupGroup(name); err != nil {
 			return fmsg.WrapError(err,
 				fmt.Sprintf("unknown group %q", name))
 		} else {
-			seal.sys.user.supp[i] = g.Gid
+			seal.user.supp[i] = g.Gid
 		}
 	}
 
-	// build extra perms
-	seal.extraPerms = make([]*sealedExtraPerm, len(config.Confinement.ExtraPerms))
-	for i, p := range config.Confinement.ExtraPerms {
-		if p == nil {
-			continue
+	// 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
 		}
-
-		seal.extraPerms[i] = new(sealedExtraPerm)
-		seal.extraPerms[i].name = p.Path
-		seal.extraPerms[i].perms = make(acl.Perms, 0, 3)
-		if p.Read {
-			seal.extraPerms[i].perms = append(seal.extraPerms[i].perms, acl.Read)
-		}
-		if p.Write {
-			seal.extraPerms[i].perms = append(seal.extraPerms[i].perms, acl.Write)
-		}
-		if p.Execute {
-			seal.extraPerms[i].perms = append(seal.extraPerms[i].perms, acl.Execute)
-		}
-		seal.extraPerms[i].ensure = p.Ensure
 	}
+	// do not use the value of shell before this point
 
-	// map sandbox config to bwrap
+	// permissive defaults
 	if config.Confinement.Sandbox == nil {
-		fmsg.VPrintln("sandbox configuration not supplied, PROCEED WITH CAUTION")
+		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 = config.Confinement.Shell
+			}
+		}
 
-		// permissive defaults
 		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 := a.os.ReadDir("/"); err != nil {
+		if d, err := sys.ReadDir("/"); err != nil {
 			return err
 		} else {
 			b := make([]*fst.FilesystemConfig, 0, len(d))
@@ -224,11 +262,11 @@ func (a *app) Seal(config *fst.Config) error {
 
 		// hide nscd from sandbox if present
 		nscd := "/var/run/nscd"
-		if _, err := a.os.Stat(nscd); !errors.Is(err, fs.ErrNotExist) {
-			conf.Override = append(conf.Override, nscd)
+		if _, err := sys.Stat(nscd); !errors.Is(err, fs.ErrNotExist) {
+			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
@@ -236,38 +274,288 @@ func (a *app) Seal(config *fst.Config) error {
 
 		config.Confinement.Sandbox = conf
 	}
-	seal.directWayland = config.Confinement.Sandbox.DirectWayland
-	if b, err := config.Confinement.Sandbox.Bwrap(a.os); err != nil {
-		return err
-	} else {
-		seal.sys.bwrap = b
-	}
-	seal.sys.override = config.Confinement.Sandbox.Override
-	if seal.sys.bwrap.SetEnv == nil {
-		seal.sys.bwrap.SetEnv = make(map[string]string)
+
+	var mapuid, mapgid *stringPair[int]
+	{
+		var uid, gid int
+		var err error
+		seal.container, seal.env, err = config.Confinement.Sandbox.ToContainer(sys, &uid, &gid)
+		if err != nil {
+			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)
+		mapgid = newInt(gid)
+		if seal.env == nil {
+			seal.env = make(map[string]string, 1<<6)
+		}
 	}
 
-	// open process state store
-	// the simple store only starts holding an open file after first action
-	// store activity begins after Start is called and must end before Wait
-	seal.store = state.NewMulti(seal.RunDirPath)
+	// 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)
+	seal.env[xdgRuntimeDir] = innerRuntimeDir
+	seal.env[xdgSessionClass] = "user"
+	seal.env[xdgSessionType] = "tty"
 
-	// initialise system interface with full uid
-	seal.sys.I = system.New(seal.sys.user.uid)
+	share := &shareHost{seal: seal, sc: sys.Paths()}
+	seal.runDirPath = share.sc.RunDirPath
+	seal.sys = system.New(seal.user.uid.unwrap())
 
-	// pass through enablements
-	seal.et = config.Confinement.Enablements
-
-	// this method calls all share methods in sequence
-	if err := seal.setupShares([2]*dbus.Config{config.Confinement.SessionBus, config.Confinement.SystemBus}, a.os); err != nil {
-		return err
+	{
+		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)
 	}
 
-	// verbose log seal information
-	fmsg.VPrintf("created application seal for uid %s (%s) groups: %v, command: %s",
-		seal.sys.user.us, seal.sys.user.username, config.Confinement.Groups, config.Command)
+	{
+		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
+
+		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"))
+	}
+
+	// pass TERM for proper terminal I/O in initial process
+	if t, ok := sys.LookupEnv(term); ok {
+		seal.env[term] = t
+	}
+
+	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 {
+			fmsg.Verbose(wl.WaylandDisplay + " is not set, assuming " + wl.FallbackName)
+			socketPath = path.Join(share.sc.RuntimePath, wl.FallbackName)
+		} else if !path.IsAbs(name) {
+			socketPath = path.Join(share.sc.RuntimePath, name)
+		} else {
+			socketPath = name
+		}
+
+		innerPath := path.Join(innerRuntimeDir, wl.FallbackName)
+		seal.env[wl.WaylandDisplay] = wl.FallbackName
+
+		if !config.Confinement.Sandbox.DirectWayland { // set up security-context-v1
+			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)
+		}
+	}
+
+	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.env[display] = d
+			seal.container.Bind("/tmp/.X11-unix", "/tmp/.X11-unix", 0)
+		}
+	}
+
+	if config.Confinement.Enablements&system.EPulse != 0 {
+		// PulseAudio runtime directory (usually `/run/user/%d/pulse`)
+		pulseRuntimeDir := path.Join(share.sc.RuntimePath, "pulse")
+		// PulseAudio socket (usually `/run/user/%d/pulse/native`)
+		pulseSocket := path.Join(pulseRuntimeDir, "native")
+
+		if _, err := sys.Stat(pulseRuntimeDir); err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				return fmsg.WrapErrorSuffix(err,
+					fmt.Sprintf("cannot access PulseAudio directory %q:", pulseRuntimeDir))
+			}
+			return fmsg.WrapError(ErrPulseSocket,
+				fmt.Sprintf("PulseAudio directory %q not found", pulseRuntimeDir))
+		}
+
+		if s, err := sys.Stat(pulseSocket); err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				return fmsg.WrapErrorSuffix(err,
+					fmt.Sprintf("cannot access PulseAudio socket %q:", pulseSocket))
+			}
+			return fmsg.WrapError(ErrPulseSocket,
+				fmt.Sprintf("PulseAudio directory %q found but socket does not exist", pulseRuntimeDir))
+		} else {
+			if m := s.Mode(); m&0o006 != 0o006 {
+				return fmsg.WrapError(ErrPulseMode,
+					fmt.Sprintf("unexpected permissions on %q:", pulseSocket), m)
+			}
+		}
+
+		// hard link pulse socket into target-executable share
+		innerPulseRuntimeDir := path.Join(share.runtime(), "pulse")
+		innerPulseSocket := path.Join(innerRuntimeDir, "pulse", "native")
+		seal.sys.Link(pulseSocket, innerPulseRuntimeDir)
+		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 {
+			// not fatal
+			fmsg.Verbose(strings.TrimSpace(err.(*fmsg.BaseError).Message()))
+		} else {
+			innerDst := fst.Tmp + "/pulse-cookie"
+			seal.env[pulseCookie] = innerDst
+			var payload *[]byte
+			seal.container.PlaceP(innerDst, &payload)
+			seal.sys.CopyFile(payload, src, 256, 256)
+		}
+	}
+
+	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)
+		}
+
+		// downstream socket paths
+		sharePath := share.instance()
+		sessionPath, systemPath := path.Join(sharePath, "bus"), path.Join(sharePath, "system_bus_socket")
+
+		// configure dbus proxy
+		if f, err := seal.sys.ProxyDBus(
+			config.Confinement.SessionBus, config.Confinement.SystemBus,
+			sessionPath, systemPath,
+		); err != nil {
+			return err
+		} else {
+			seal.dbusMsg = f
+		}
+
+		// share proxy sockets
+		sessionInner := path.Join(innerRuntimeDir, "bus")
+		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.env[dbusSystemBusAddress] = "unix:path=" + systemInner
+			seal.container.Bind(systemPath, systemInner, 0)
+			seal.sys.UpdatePerm(systemPath, acl.Read, acl.Write)
+		}
+	}
+
+	for _, dest := range config.Confinement.Sandbox.Cover {
+		seal.container.Tmpfs(dest, 1<<13, 0755)
+	}
+
+	// append ExtraPerms last
+	for _, p := range config.Confinement.ExtraPerms {
+		if p == nil {
+			continue
+		}
+
+		if p.Ensure {
+			seal.sys.Ensure(p.Path, 0700)
+		}
+
+		perms := make(acl.Perms, 0, 3)
+		if p.Read {
+			perms = append(perms, acl.Read)
+		}
+		if p.Write {
+			perms = append(perms, acl.Write)
+		}
+		if p.Execute {
+			perms = append(perms, acl.Execute)
+		}
+		seal.sys.UpdatePermType(system.User, p.Path, perms...)
+	}
+
+	// flatten and sort env for deterministic behaviour
+	seal.container.Env = make([]string, 0, len(seal.env))
+	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",
+		seal.user.uid, seal.user.username, config.Confinement.Groups, seal.container.Args)
 
-	// seal app and release lock
-	a.seal = seal
 	return nil
 }
+
+// discoverPulseCookie attempts various standard methods to discover the current user's PulseAudio authentication cookie
+func discoverPulseCookie(sys sys.State) (string, error) {
+	if p, ok := sys.LookupEnv(pulseCookie); ok {
+		return p, nil
+	}
+
+	// dotfile $HOME/.pulse-cookie
+	if p, ok := sys.LookupEnv(home); ok {
+		p = path.Join(p, ".pulse-cookie")
+		if s, err := sys.Stat(p); err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				return p, fmsg.WrapErrorSuffix(err,
+					fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
+			}
+			// not found, try next method
+		} else if !s.IsDir() {
+			return p, nil
+		}
+	}
+
+	// $XDG_CONFIG_HOME/pulse/cookie
+	if p, ok := sys.LookupEnv(xdgConfigHome); ok {
+		p = path.Join(p, "pulse", "cookie")
+		if s, err := sys.Stat(p); err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				return p, fmsg.WrapErrorSuffix(err,
+					fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
+			}
+			// not found, try next method
+		} else if !s.IsDir() {
+			return p, nil
+		}
+	}
+
+	return "", fmsg.WrapError(ErrPulseCookie,
+		fmt.Sprintf("cannot locate PulseAudio cookie (tried $%s, $%s/pulse/cookie, $%s/.pulse-cookie)",
+			pulseCookie, xdgConfigHome, home))
+}

internal/app/share.go

@@ -1,339 +0,0 @@
-package app
-
-import (
-	"errors"
-	"fmt"
-	"io/fs"
-	"path"
-	"strings"
-
-	"git.gensokyo.uk/security/fortify/acl"
-	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/linux"
-	"git.gensokyo.uk/security/fortify/internal/system"
-	"git.gensokyo.uk/security/fortify/wl"
-)
-
-const (
-	home  = "HOME"
-	shell = "SHELL"
-
-	xdgConfigHome   = "XDG_CONFIG_HOME"
-	xdgRuntimeDir   = "XDG_RUNTIME_DIR"
-	xdgSessionClass = "XDG_SESSION_CLASS"
-	xdgSessionType  = "XDG_SESSION_TYPE"
-
-	term    = "TERM"
-	display = "DISPLAY"
-
-	pulseServer = "PULSE_SERVER"
-	pulseCookie = "PULSE_COOKIE"
-
-	dbusSessionBusAddress = "DBUS_SESSION_BUS_ADDRESS"
-	dbusSystemBusAddress  = "DBUS_SYSTEM_BUS_ADDRESS"
-)
-
-var (
-	ErrXDisplay = errors.New(display + " unset")
-
-	ErrPulseCookie = errors.New("pulse cookie not present")
-	ErrPulseSocket = errors.New("pulse socket not present")
-	ErrPulseMode   = errors.New("unexpected pulse socket mode")
-)
-
-func (seal *appSeal) setupShares(bus [2]*dbus.Config, os linux.System) error {
-	if seal.shared {
-		panic("seal shared twice")
-	}
-	seal.shared = true
-
-	/*
-		Tmpdir-based share directory
-	*/
-
-	// ensure Share (e.g. `/tmp/fortify.%d`)
-	// acl is unnecessary as this directory is world executable
-	seal.sys.Ensure(seal.SharePath, 0711)
-
-	// ensure process-specific share (e.g. `/tmp/fortify.%d/%s`)
-	// acl is unnecessary as this directory is world executable
-	seal.share = path.Join(seal.SharePath, seal.id)
-	seal.sys.Ephemeral(system.Process, seal.share, 0711)
-
-	// ensure child tmpdir parent directory (e.g. `/tmp/fortify.%d/tmpdir`)
-	targetTmpdirParent := path.Join(seal.SharePath, "tmpdir")
-	seal.sys.Ensure(targetTmpdirParent, 0700)
-	seal.sys.UpdatePermType(system.User, targetTmpdirParent, acl.Execute)
-
-	// ensure child tmpdir (e.g. `/tmp/fortify.%d/tmpdir/%d`)
-	targetTmpdir := path.Join(targetTmpdirParent, seal.sys.user.as)
-	seal.sys.Ensure(targetTmpdir, 01700)
-	seal.sys.UpdatePermType(system.User, targetTmpdir, acl.Read, acl.Write, acl.Execute)
-	seal.sys.bwrap.Bind(targetTmpdir, "/tmp", false, true)
-
-	/*
-		XDG runtime directory
-	*/
-
-	// mount tmpfs on inner runtime (e.g. `/run/user/%d`)
-	seal.sys.bwrap.Tmpfs("/run/user", 1*1024*1024)
-	seal.sys.bwrap.Tmpfs(seal.sys.runtime, 8*1024*1024)
-
-	// point to inner runtime path `/run/user/%d`
-	seal.sys.bwrap.SetEnv[xdgRuntimeDir] = seal.sys.runtime
-	seal.sys.bwrap.SetEnv[xdgSessionClass] = "user"
-	seal.sys.bwrap.SetEnv[xdgSessionType] = "tty"
-
-	// ensure RunDir (e.g. `/run/user/%d/fortify`)
-	seal.sys.Ensure(seal.RunDirPath, 0700)
-	seal.sys.UpdatePermType(system.User, seal.RunDirPath, acl.Execute)
-
-	// ensure runtime directory ACL (e.g. `/run/user/%d`)
-	seal.sys.Ensure(seal.RuntimePath, 0700) // ensure this dir in case XDG_RUNTIME_DIR is unset
-	seal.sys.UpdatePermType(system.User, seal.RuntimePath, acl.Execute)
-
-	// ensure process-specific share local to XDG_RUNTIME_DIR (e.g. `/run/user/%d/fortify/%s`)
-	seal.shareLocal = path.Join(seal.RunDirPath, seal.id)
-	seal.sys.Ephemeral(system.Process, seal.shareLocal, 0700)
-	seal.sys.UpdatePerm(seal.shareLocal, acl.Execute)
-
-	/*
-		Inner passwd database
-	*/
-
-	// look up shell
-	sh := "/bin/sh"
-	if s, ok := os.LookupEnv(shell); ok {
-		seal.sys.bwrap.SetEnv[shell] = s
-		sh = s
-	}
-
-	// bind home directory
-	homeDir := "/var/empty"
-	if seal.sys.user.home != "" {
-		homeDir = seal.sys.user.home
-	}
-	username := "chronos"
-	if seal.sys.user.username != "" {
-		username = seal.sys.user.username
-	}
-	seal.sys.bwrap.Bind(seal.sys.user.data, homeDir, false, true)
-	seal.sys.bwrap.Chdir = homeDir
-	seal.sys.bwrap.SetEnv["HOME"] = homeDir
-	seal.sys.bwrap.SetEnv["USER"] = username
-
-	// generate /etc/passwd and /etc/group
-	seal.sys.bwrap.CopyBind("/etc/passwd",
-		[]byte(username+":x:"+seal.sys.mappedIDString+":"+seal.sys.mappedIDString+":Fortify:"+homeDir+":"+sh+"\n"))
-	seal.sys.bwrap.CopyBind("/etc/group",
-		[]byte("fortify:x:"+seal.sys.mappedIDString+":\n"))
-
-	/*
-		Display servers
-	*/
-
-	// pass $TERM to launcher
-	if t, ok := os.LookupEnv(term); ok {
-		seal.sys.bwrap.SetEnv[term] = t
-	}
-
-	// set up wayland
-	if seal.et.Has(system.EWayland) {
-		var socketPath string
-		if name, ok := os.LookupEnv(wl.WaylandDisplay); !ok {
-			fmsg.VPrintln(wl.WaylandDisplay + " is not set, assuming " + wl.FallbackName)
-			socketPath = path.Join(seal.RuntimePath, wl.FallbackName)
-		} else if !path.IsAbs(name) {
-			socketPath = path.Join(seal.RuntimePath, name)
-		} else {
-			socketPath = name
-		}
-
-		innerPath := path.Join(seal.sys.runtime, wl.FallbackName)
-		seal.sys.bwrap.SetEnv[wl.WaylandDisplay] = wl.FallbackName
-
-		if !seal.directWayland { // set up security-context-v1
-			socketDir := path.Join(seal.SharePath, "wayland")
-			outerPath := path.Join(socketDir, seal.id)
-			seal.sys.Ensure(socketDir, 0711)
-			appID := seal.fid
-			if appID == "" {
-				// use instance ID in case app id is not set
-				appID = "uk.gensokyo.fortify." + seal.id
-			}
-			seal.sys.Wayland(outerPath, socketPath, appID, seal.id)
-			seal.sys.bwrap.Bind(outerPath, innerPath)
-		} else { // bind mount wayland socket (insecure)
-			fmsg.VPrintln("direct wayland access, PROCEED WITH CAUTION")
-			seal.sys.bwrap.Bind(socketPath, innerPath)
-
-			// ensure Wayland socket ACL (e.g. `/run/user/%d/wayland-%d`)
-			seal.sys.UpdatePermType(system.EWayland, socketPath, acl.Read, acl.Write, acl.Execute)
-		}
-	}
-
-	// set up X11
-	if seal.et.Has(system.EX11) {
-		// discover X11 and grant user permission via the `ChangeHosts` command
-		if d, ok := os.LookupEnv(display); !ok {
-			return fmsg.WrapError(ErrXDisplay,
-				"DISPLAY is not set")
-		} else {
-			seal.sys.ChangeHosts("#" + seal.sys.user.us)
-			seal.sys.bwrap.SetEnv[display] = d
-			seal.sys.bwrap.Bind("/tmp/.X11-unix", "/tmp/.X11-unix")
-		}
-	}
-
-	/*
-		PulseAudio server and authentication
-	*/
-
-	if seal.et.Has(system.EPulse) {
-		// check PulseAudio directory presence (e.g. `/run/user/%d/pulse`)
-		pd := path.Join(seal.RuntimePath, "pulse")
-		ps := path.Join(pd, "native")
-		if _, err := os.Stat(pd); err != nil {
-			if !errors.Is(err, fs.ErrNotExist) {
-				return fmsg.WrapErrorSuffix(err,
-					fmt.Sprintf("cannot access PulseAudio directory %q:", pd))
-			}
-			return fmsg.WrapError(ErrPulseSocket,
-				fmt.Sprintf("PulseAudio directory %q not found", pd))
-		}
-
-		// check PulseAudio socket permission (e.g. `/run/user/%d/pulse/native`)
-		if s, err := os.Stat(ps); err != nil {
-			if !errors.Is(err, fs.ErrNotExist) {
-				return fmsg.WrapErrorSuffix(err,
-					fmt.Sprintf("cannot access PulseAudio socket %q:", ps))
-			}
-			return fmsg.WrapError(ErrPulseSocket,
-				fmt.Sprintf("PulseAudio directory %q found but socket does not exist", pd))
-		} else {
-			if m := s.Mode(); m&0o006 != 0o006 {
-				return fmsg.WrapError(ErrPulseMode,
-					fmt.Sprintf("unexpected permissions on %q:", ps), m)
-			}
-		}
-
-		// hard link pulse socket into target-executable share
-		psi := path.Join(seal.shareLocal, "pulse")
-		p := path.Join(seal.sys.runtime, "pulse", "native")
-		seal.sys.Link(ps, psi)
-		seal.sys.bwrap.Bind(psi, p)
-		seal.sys.bwrap.SetEnv[pulseServer] = "unix:" + p
-
-		// publish current user's pulse cookie for target user
-		if src, err := discoverPulseCookie(os); err != nil {
-			// not fatal
-			fmsg.VPrintln(strings.TrimSpace(err.(*fmsg.BaseError).Message()))
-		} else {
-			dst := path.Join(seal.share, "pulse-cookie")
-			innerDst := fst.Tmp + "/pulse-cookie"
-			seal.sys.bwrap.SetEnv[pulseCookie] = innerDst
-			seal.sys.CopyFile(dst, src)
-			seal.sys.bwrap.Bind(dst, innerDst)
-		}
-	}
-
-	/*
-		D-Bus proxy
-	*/
-
-	if seal.et.Has(system.EDBus) {
-		// ensure dbus session bus defaults
-		if bus[0] == nil {
-			bus[0] = dbus.NewConfig(seal.fid, true, true)
-		}
-
-		// downstream socket paths
-		sessionPath, systemPath := path.Join(seal.share, "bus"), path.Join(seal.share, "system_bus_socket")
-
-		// configure dbus proxy
-		if f, err := seal.sys.ProxyDBus(bus[0], bus[1], sessionPath, systemPath); err != nil {
-			return err
-		} else {
-			seal.dbusMsg = f
-		}
-
-		// share proxy sockets
-		sessionInner := path.Join(seal.sys.runtime, "bus")
-		seal.sys.bwrap.SetEnv[dbusSessionBusAddress] = "unix:path=" + sessionInner
-		seal.sys.bwrap.Bind(sessionPath, sessionInner)
-		seal.sys.UpdatePerm(sessionPath, acl.Read, acl.Write)
-		if bus[1] != nil {
-			systemInner := "/run/dbus/system_bus_socket"
-			seal.sys.bwrap.SetEnv[dbusSystemBusAddress] = "unix:path=" + systemInner
-			seal.sys.bwrap.Bind(systemPath, systemInner)
-			seal.sys.UpdatePerm(systemPath, acl.Read, acl.Write)
-		}
-	}
-
-	/*
-		Miscellaneous
-	*/
-
-	// queue overriding tmpfs at the end of seal.sys.bwrap.Filesystem
-	for _, dest := range seal.sys.override {
-		seal.sys.bwrap.Tmpfs(dest, 8*1024)
-	}
-
-	// mount fortify in sandbox for init
-	seal.sys.bwrap.Bind(os.MustExecutable(), path.Join(fst.Tmp, "sbin/fortify"))
-	seal.sys.bwrap.Symlink("fortify", path.Join(fst.Tmp, "sbin/init"))
-
-	// append extra perms
-	for _, p := range seal.extraPerms {
-		if p == nil {
-			continue
-		}
-		if p.ensure {
-			seal.sys.Ensure(p.name, 0700)
-		}
-		seal.sys.UpdatePermType(system.User, p.name, p.perms...)
-	}
-
-	return nil
-}
-
-// discoverPulseCookie attempts various standard methods to discover the current user's PulseAudio authentication cookie
-func discoverPulseCookie(os linux.System) (string, error) {
-	if p, ok := os.LookupEnv(pulseCookie); ok {
-		return p, nil
-	}
-
-	// dotfile $HOME/.pulse-cookie
-	if p, ok := os.LookupEnv(home); ok {
-		p = path.Join(p, ".pulse-cookie")
-		if s, err := os.Stat(p); err != nil {
-			if !errors.Is(err, fs.ErrNotExist) {
-				return p, fmsg.WrapErrorSuffix(err,
-					fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
-			}
-			// not found, try next method
-		} else if !s.IsDir() {
-			return p, nil
-		}
-	}
-
-	// $XDG_CONFIG_HOME/pulse/cookie
-	if p, ok := os.LookupEnv(xdgConfigHome); ok {
-		p = path.Join(p, "pulse", "cookie")
-		if s, err := os.Stat(p); err != nil {
-			if !errors.Is(err, fs.ErrNotExist) {
-				return p, fmsg.WrapErrorSuffix(err,
-					fmt.Sprintf("cannot access PulseAudio cookie %q:", p))
-			}
-			// not found, try next method
-		} else if !s.IsDir() {
-			return p, nil
-		}
-	}
-
-	return "", fmsg.WrapError(ErrPulseCookie,
-		fmt.Sprintf("cannot locate PulseAudio cookie (tried $%s, $%s/pulse/cookie, $%s/.pulse-cookie)",
-			pulseCookie, xdgConfigHome, home))
-}

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/start.go

@@ -1,266 +0,0 @@
-package app
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"os/exec"
-	"path/filepath"
-	"strings"
-	"time"
-
-	"git.gensokyo.uk/security/fortify/helper"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
-	"git.gensokyo.uk/security/fortify/internal/state"
-	"git.gensokyo.uk/security/fortify/internal/system"
-)
-
-const shimSetupTimeout = 5 * time.Second
-
-func (a *app) Run(ctx context.Context, rs *RunState) error {
-	a.lock.Lock()
-	defer a.lock.Unlock()
-
-	if rs == nil {
-		panic("attempted to pass nil state to run")
-	}
-
-	// resolve exec paths
-	shimExec := [2]string{helper.BubblewrapName}
-	if len(a.seal.command) > 0 {
-		shimExec[1] = a.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))
-			}
-		}
-	}
-
-	// startup will go ahead, commit system setup
-	if err := a.seal.sys.Commit(ctx); err != nil {
-		return err
-	}
-	a.seal.sys.needRevert = true
-
-	// start shim via manager
-	a.shim = new(shim.Shim)
-	waitErr := make(chan error, 1)
-	if startTime, err := a.shim.Start(
-		a.seal.sys.user.as,
-		a.seal.sys.user.supp,
-		a.seal.sys.Sync(),
-	); err != nil {
-		return err
-	} else {
-		// shim process created
-		rs.Start = true
-
-		shimSetupCtx, shimSetupCancel := context.WithDeadline(ctx, time.Now().Add(shimSetupTimeout))
-		defer shimSetupCancel()
-
-		// start waiting for shim
-		go func() {
-			waitErr <- a.shim.Unwrap().Wait()
-			// cancel shim setup in case shim died before receiving payload
-			shimSetupCancel()
-		}()
-
-		// send payload
-		if err = a.shim.Serve(shimSetupCtx, &shim.Payload{
-			Argv:  a.seal.command,
-			Exec:  shimExec,
-			Bwrap: a.seal.sys.bwrap,
-			Home:  a.seal.sys.user.data,
-
-			Verbose: fmsg.Verbose(),
-		}); err != nil {
-			return err
-		}
-
-		// shim accepted setup payload, create process state
-		sd := state.State{
-			ID:   *a.id,
-			PID:  a.shim.Unwrap().Process.Pid,
-			Time: *startTime,
-		}
-
-		// register process state
-		var err0 = new(StateStoreError)
-		err0.Inner, err0.DoErr = a.seal.store.Do(a.seal.sys.user.aid, func(c state.Cursor) {
-			err0.InnerErr = c.Save(&sd, a.seal.ct)
-		})
-		a.seal.sys.saveState = true
-		if err = err0.equiv("cannot save process state:"); err != nil {
-			return err
-		}
-	}
-
-	select {
-	// wait for process and resolve exit code
-	case err := <-waitErr:
-		if err != nil {
-			var exitError *exec.ExitError
-			if !errors.As(err, &exitError) {
-				// should be unreachable
-				rs.WaitErr = err
-			}
-
-			// store non-zero return code
-			rs.ExitCode = exitError.ExitCode()
-		} else {
-			rs.ExitCode = a.shim.Unwrap().ProcessState.ExitCode()
-		}
-		if fmsg.Verbose() {
-			fmsg.VPrintf("process %d exited with exit code %d", a.shim.Unwrap().Process.Pid, rs.ExitCode)
-		}
-
-	// 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 := <-a.shim.WaitFallback():
-		rs.ExitCode = 255
-		fmsg.Printf("cannot terminate shim on faulted setup: %v", err)
-
-	// alternative exit path relying on shim behaviour on monitor process exit
-	case <-ctx.Done():
-		fmsg.VPrintln("alternative exit path selected")
-	}
-
-	// child process exited, resume output
-	fmsg.Resume()
-
-	// print queued up dbus messages
-	if a.seal.dbusMsg != nil {
-		a.seal.dbusMsg()
-	}
-
-	// update store and revert app setup transaction
-	e := new(StateStoreError)
-	e.Inner, e.DoErr = a.seal.store.Do(a.seal.sys.user.aid, func(b state.Cursor) {
-		e.InnerErr = func() error {
-			// destroy defunct state entry
-			if cmd := a.shim.Unwrap(); cmd != nil && a.seal.sys.saveState {
-				if err := b.Destroy(*a.id); err != nil {
-					return err
-				}
-			}
-
-			// enablements of remaining launchers
-			rt, ec := new(system.Enablements), new(system.Criteria)
-			ec.Enablements = new(system.Enablements)
-			ec.Set(system.Process)
-			if states, err := b.Load(); err != nil {
-				return err
-			} else {
-				if l := len(states); l == 0 {
-					// cleanup globals as the final launcher
-					fmsg.VPrintln("no other launchers active, will clean up globals")
-					ec.Set(system.User)
-				} else {
-					fmsg.VPrintf("found %d active launchers, cleaning up without globals", l)
-				}
-
-				// accumulate capabilities of other launchers
-				for i, s := range states {
-					if s.Config != nil {
-						*rt |= s.Config.Confinement.Enablements
-					} else {
-						fmsg.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)
-				}
-			}
-			if fmsg.Verbose() {
-				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.VPrintln("reverting operations labelled", strings.Join(labels, ", "))
-				}
-			}
-
-			if a.seal.sys.needRevert {
-				if err := a.seal.sys.Revert(ec); err != nil {
-					return err.(RevertCompoundError)
-				}
-			}
-
-			return nil
-		}()
-	})
-
-	e.Err = a.seal.store.Close()
-	return e.equiv("error returned during cleanup:", e)
-}
-
-// StateStoreError is returned for a failed state save
-type StateStoreError struct {
-	// whether inner function was called
-	Inner bool
-	// error returned by state.Store Do method
-	DoErr error
-	// error returned by state.Backend Save method
-	InnerErr error
-	// any other errors needing to be tracked
-	Err error
-}
-
-func (e *StateStoreError) equiv(a ...any) error {
-	if e.Inner && e.DoErr == nil && e.InnerErr == nil && e.Err == nil {
-		return nil
-	} else {
-		return fmsg.WrapErrorSuffix(e, a...)
-	}
-}
-
-func (e *StateStoreError) Error() string {
-	if e.Inner && e.InnerErr != nil {
-		return e.InnerErr.Error()
-	}
-
-	if e.DoErr != nil {
-		return e.DoErr.Error()
-	}
-
-	if e.Err != nil {
-		return e.Err.Error()
-	}
-
-	return "(nil)"
-}
-
-func (e *StateStoreError) Unwrap() (errs []error) {
-	errs = make([]error, 0, 3)
-	if e.DoErr != nil {
-		errs = append(errs, e.DoErr)
-	}
-	if e.InnerErr != nil {
-		errs = append(errs, e.InnerErr)
-	}
-	if e.Err != nil {
-		errs = append(errs, e.Err)
-	}
-	return
-}
-
-type RevertCompoundError interface {
-	Error() string
-	Unwrap() []error
-}

internal/app/strings.go

@@ -0,0 +1,19 @@
+package app
+
+import (
+	"strconv"
+
+	"git.gensokyo.uk/security/fortify/fst"
+)
+
+func newInt(v int) *stringPair[int]        { return &stringPair[int]{v, strconv.Itoa(v)} }
+func newID(id *fst.ID) *stringPair[fst.ID] { return &stringPair[fst.ID]{*id, id.String()} }
+
+// stringPair stores a value and its string representation.
+type stringPair[T comparable] struct {
+	v T
+	s string
+}
+
+func (s *stringPair[T]) unwrap() T      { return s.v }
+func (s *stringPair[T]) String() string { return s.s }

internal/app/system.go

@@ -1,51 +0,0 @@
-package app
-
-import (
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/system"
-)
-
-// appSealSys encapsulates app seal behaviour with OS interactions
-type appSealSys struct {
-	bwrap *bwrap.Config
-	// paths to override by mounting tmpfs over them
-	override []string
-
-	// default formatted XDG_RUNTIME_DIR of User
-	runtime string
-	// target user sealed from config
-	user appUser
-
-	// mapped uid and gid in user namespace
-	mappedID int
-	// string representation of mappedID
-	mappedIDString string
-
-	needRevert bool
-	saveState  bool
-	*system.I
-
-	// protected by upstream mutex
-}
-
-type appUser struct {
-	// full uid resolved by fsu
-	uid int
-	// string representation of uid
-	us string
-
-	// supplementary group ids
-	supp []string
-
-	// application id
-	aid int
-	// string representation of aid
-	as string
-
-	// home directory host path
-	data string
-	// app user home directory
-	home string
-	// passwd database username
-	username string
-}

internal/comp.go

@@ -3,10 +3,15 @@ package internal
 const compPoison = "INVALIDINVALIDINVALIDINVALIDINVALID"
 
 var (
-	Version = compPoison
+	version = compPoison
 )
 
-// Check validates string value set at compile time.
-func Check(s string) (string, bool) {
-	return s, s != compPoison && s != ""
+// check validates string value set at compile time.
+func check(s string) (string, bool) { return s, s != compPoison && s != "" }
+
+func Version() string {
+	if v, ok := check(version); ok {
+		return v
+	}
+	return "impure"
 }

internal/exit.go

@@ -0,0 +1,9 @@
+package internal
+
+import (
+	"os"
+
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+)
+
+func Exit(code int) { fmsg.BeforeExit(); os.Exit(code) }

internal/fmsg/defer.go

@@ -1,98 +0,0 @@
-package fmsg
-
-import (
-	"os"
-	"sync"
-	"sync/atomic"
-)
-
-var (
-	wstate   atomic.Bool
-	dropped  atomic.Uint64
-	withhold = make(chan struct{}, 1)
-	msgbuf   = make(chan dOp, 64) // these ops are tiny so a large buffer is allocated for withholding output
-
-	dequeueOnce sync.Once
-	queueSync   sync.WaitGroup
-)
-
-func dequeue() {
-	go func() {
-		for {
-			select {
-			case op := <-msgbuf:
-				op.Do()
-				queueSync.Done()
-			case <-withhold:
-				<-withhold
-			}
-		}
-	}()
-}
-
-// queue submits ops to msgbuf but drops messages
-// when the buffer is full and dequeue is withholding
-func queue(op dOp) {
-	queueSync.Add(1)
-
-	select {
-	case msgbuf <- op:
-	default:
-		// send the op anyway if not withholding
-		// as dequeue will get to it eventually
-		if !wstate.Load() {
-			msgbuf <- op
-		} else {
-			queueSync.Done()
-			// increment dropped message count
-			dropped.Add(1)
-		}
-	}
-}
-
-type dOp interface{ Do() }
-
-func Exit(code int) {
-	Resume() // resume here to avoid deadlock
-	queueSync.Wait()
-	os.Exit(code)
-}
-
-func Suspend() {
-	dequeueOnce.Do(dequeue)
-	if wstate.CompareAndSwap(false, true) {
-		queueSync.Wait()
-		withhold <- struct{}{}
-	}
-}
-
-func Resume() {
-	dequeueOnce.Do(dequeue)
-	if wstate.CompareAndSwap(true, false) {
-		withhold <- struct{}{}
-		if d := dropped.Swap(0); d != 0 {
-			Printf("dropped %d messages during withhold", d)
-		}
-	}
-}
-
-type dPrint []any
-
-func (v dPrint) Do() {
-	std.Print(v...)
-}
-
-type dPrintf struct {
-	format string
-	v      []any
-}
-
-func (d *dPrintf) Do() {
-	std.Printf(d.format, d.v...)
-}
-
-type dPrintln []any
-
-func (v dPrintln) Do() {
-	std.Println(v...)
-}

internal/fmsg/errors.go

@@ -2,7 +2,9 @@ package fmsg
 
 import (
 	"fmt"
+	"log"
 	"reflect"
+	"strings"
 )
 
 // baseError implements a basic error container
@@ -70,3 +72,17 @@ func AsBaseError(err error, target **BaseError) bool {
 	*target = v.Convert(baseErrorType).Interface().(*BaseError)
 	return true
 }
+
+func PrintBaseError(err error, fallback string) {
+	var e *BaseError
+
+	if AsBaseError(err, &e) {
+		if msg := e.Message(); strings.TrimSpace(msg) != "" {
+			log.Print(msg)
+			return
+		}
+		Verbose("*"+fallback, err)
+		return
+	}
+	log.Println(fallback, err)
+}

internal/fmsg/fmsg.go

@@ -2,39 +2,85 @@
 package fmsg
 
 import (
+	"bytes"
+	"io"
 	"log"
 	"os"
+	"sync"
+	"sync/atomic"
+	"syscall"
 )
 
-var std = log.New(os.Stderr, "fortify: ", 0)
+const (
+	bufSize    = 4 * 1024
+	bufSizeMax = 16 * 1024 * 1024
+)
 
-func SetPrefix(prefix string) {
-	prefix += ": "
-	std.SetPrefix(prefix)
-	std.SetPrefix(prefix)
+var o = &suspendable{w: os.Stderr}
+
+// Prepare configures the system logger for [Suspend] and [Resume] to take effect.
+func Prepare(prefix string) { log.SetPrefix(prefix + ": "); log.SetFlags(0); log.SetOutput(o) }
+
+type suspendable struct {
+	w io.Writer
+	s atomic.Bool
+
+	buf     bytes.Buffer
+	bufOnce sync.Once
+	bufMu   sync.Mutex
+	dropped int
 }
 
-func Print(v ...any) {
-	dequeueOnce.Do(dequeue)
-	queue(dPrint(v))
+func (s *suspendable) Write(p []byte) (n int, err error) {
+	if !s.s.Load() {
+		return s.w.Write(p)
+	}
+	s.bufOnce.Do(func() { s.prepareBuf() })
+
+	s.bufMu.Lock()
+	defer s.bufMu.Unlock()
+
+	if l := len(p); s.buf.Len()+l > bufSizeMax {
+		s.dropped += l
+		return 0, syscall.ENOMEM
+	}
+	return s.buf.Write(p)
 }
 
-func Printf(format string, v ...any) {
-	dequeueOnce.Do(dequeue)
-	queue(&dPrintf{format, v})
+func (s *suspendable) prepareBuf()   { s.buf.Grow(bufSize) }
+func (s *suspendable) Suspend() bool { return o.s.CompareAndSwap(false, true) }
+func (s *suspendable) Resume() (resumed bool, dropped uintptr, n int64, err error) {
+	if o.s.CompareAndSwap(true, false) {
+		o.bufMu.Lock()
+		defer o.bufMu.Unlock()
+
+		resumed = true
+		dropped = uintptr(o.dropped)
+
+		o.dropped = 0
+		n, err = io.Copy(s.w, &s.buf)
+		s.buf = bytes.Buffer{}
+		s.prepareBuf()
+	}
+	return
 }
 
-func Println(v ...any) {
-	dequeueOnce.Do(dequeue)
-	queue(dPrintln(v))
+func Suspend() bool { return o.Suspend() }
+func Resume() bool {
+	resumed, dropped, _, err := o.Resume()
+	if err != nil {
+		// probably going to result in an error as well,
+		// so this call is as good as unreachable
+		log.Printf("cannot dump buffer on resume: %v", err)
+	}
+	if resumed && dropped > 0 {
+		log.Fatalf("dropped %d bytes while output is suspended", dropped)
+	}
+	return resumed
 }
 
-func Fatal(v ...any) {
-	Print(v...)
-	Exit(1)
-}
-
-func Fatalf(format string, v ...any) {
-	Printf(format, v...)
-	Exit(1)
+func BeforeExit() {
+	if Resume() {
+		log.Printf("beforeExit reached on suspended output")
+	}
 }

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/fmsg/verbose.go

@@ -1,25 +1,23 @@
 package fmsg
 
-import "sync/atomic"
+import (
+	"log"
+	"sync/atomic"
+)
 
 var verbose = new(atomic.Bool)
 
-func Verbose() bool {
-	return verbose.Load()
-}
+func Load() bool   { return verbose.Load() }
+func Store(v bool) { verbose.Store(v) }
 
-func SetVerbose(v bool) {
-	verbose.Store(v)
-}
-
-func VPrintf(format string, v ...any) {
+func Verbosef(format string, v ...any) {
 	if verbose.Load() {
-		Printf(format, v...)
+		log.Printf(format, v...)
 	}
 }
 
-func VPrintln(v ...any) {
+func Verbose(v ...any) {
 	if verbose.Load() {
-		Println(v...)
+		log.Println(v...)
 	}
 }

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/path.go

@@ -1,11 +1,23 @@
 package internal
 
-import "path"
+import (
+	"log"
+	"path"
 
-var (
-	Fsu = compPoison
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
-func Path(p string) (string, bool) {
-	return p, p != compPoison && p != "" && path.IsAbs(p)
+var (
+	fsu = compPoison
+)
+
+func MustFsuPath() string {
+	if name, ok := checkPath(fsu); ok {
+		return name
+	}
+	fmsg.BeforeExit()
+	log.Fatal("invalid fsu path, this program is compiled incorrectly")
+	return compPoison
 }
+
+func checkPath(p string) (string, bool) { return p, p != compPoison && p != "" && path.IsAbs(p) }

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/priv/init/early.go

@@ -1,18 +0,0 @@
-package init0
-
-import (
-	"os"
-	"path"
-
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
-)
-
-// 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()
-		fmsg.Exit(0)
-	}
-}

internal/priv/init/main.go

@@ -1,164 +0,0 @@
-package init0
-
-import (
-	"errors"
-	"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.SetPrefix("init")
-
-	// setting this prevents ptrace
-	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		fmsg.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
-		panic("unreachable")
-	}
-
-	if os.Getpid() != 1 {
-		fmsg.Fatal("this process must run as pid 1")
-		panic("unreachable")
-	}
-
-	// receive setup payload
-	var (
-		payload    Payload
-		closeSetup func() error
-	)
-	if f, err := proc.Receive(Env, &payload); err != nil {
-		if errors.Is(err, proc.ErrInvalid) {
-			fmsg.Fatal("invalid config descriptor")
-		}
-		if errors.Is(err, proc.ErrNotSet) {
-			fmsg.Fatal("FORTIFY_INIT not set")
-		}
-
-		fmsg.Fatalf("cannot decode init setup payload: %v", err)
-		panic("unreachable")
-	} else {
-		fmsg.SetVerbose(payload.Verbose)
-		closeSetup = f
-
-		// child does not need to see this
-		if err = os.Unsetenv(Env); err != nil {
-			fmsg.Printf("cannot unset %s: %v", Env, err)
-			// not fatal
-		} else {
-			fmsg.VPrintln("received configuration")
-		}
-	}
-
-	// die with parent
-	if err := internal.PR_SET_PDEATHSIG__SIGKILL(); err != nil {
-		fmsg.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 {
-		fmsg.Fatalf("cannot start %q: %v", payload.Argv0, err)
-	}
-	fmsg.Suspend()
-
-	// close setup pipe as setup is now complete
-	if err := closeSetup(); err != nil {
-		fmsg.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) {
-			fmsg.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:
-			fmsg.VPrintln("received", s.String())
-			fmsg.Resume() // output could still be withheld at this point, so resume is called
-			fmsg.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:
-			fmsg.Exit(r)
-		case <-timeout:
-			fmsg.Println("timeout exceeded waiting for lingering processes")
-			fmsg.Exit(r)
-		}
-	}
-}

internal/priv/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
-}