helper/bwrap: separate sequential/static args

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

dbus/address.go

@@ -0,0 +1,186 @@
+package dbus
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"slices"
+)
+
+type AddrEntry struct {
+	Method string      `json:"method"`
+	Values [][2]string `json:"values"`
+}
+
+// Parse parses D-Bus address according to
+// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses
+func Parse(addr []byte) ([]AddrEntry, error) {
+	// Look for a semicolon
+	address := bytes.Split(bytes.TrimSuffix(addr, []byte{';'}), []byte{';'})
+
+	// Allocate for entries
+	v := make([]AddrEntry, len(address))
+
+	for i, s := range address {
+		var pairs [][]byte
+
+		// Look for the colon :
+		if method, list, ok := bytes.Cut(s, []byte{':'}); !ok {
+			return v, &BadAddressError{ErrNoColon, i, s, -1, nil}
+		} else {
+			pairs = bytes.Split(list, []byte{','})
+			v[i].Method = string(method)
+			v[i].Values = make([][2]string, len(pairs))
+		}
+
+		for j, pair := range pairs {
+			key, value, ok := bytes.Cut(pair, []byte{'='})
+			if !ok {
+				return v, &BadAddressError{ErrBadPairSep, i, s, j, pair}
+			}
+			if len(key) == 0 {
+				return v, &BadAddressError{ErrBadPairKey, i, s, j, pair}
+			}
+			if len(value) == 0 {
+				return v, &BadAddressError{ErrBadPairVal, i, s, j, pair}
+			}
+			v[i].Values[j][0] = string(key)
+
+			if val, errno := unescapeValue(value); errno != errSuccess {
+				return v, &BadAddressError{errno, i, s, j, pair}
+			} else {
+				v[i].Values[j][1] = string(val)
+			}
+		}
+	}
+
+	return v, nil
+}
+
+func unescapeValue(v []byte) (val []byte, errno ParseError) {
+	if l := len(v) - (bytes.Count(v, []byte{'%'}) * 2); l < 0 {
+		errno = ErrBadValLength
+		return
+	} else {
+		val = make([]byte, l)
+	}
+
+	var i, skip int
+	for iu, b := range v {
+		if skip > 0 {
+			skip--
+			continue
+		}
+
+		if ib := bytes.IndexByte([]byte("-_/.\\*"), b); ib != -1 { // - // _/.\*
+			goto opt
+		} else if b >= '0' && b <= '9' { // 0-9
+			goto opt
+		} else if b >= 'A' && b <= 'Z' { // A-Z
+			goto opt
+		} else if b >= 'a' && b <= 'z' { // a-z
+			goto opt
+		}
+
+		if b != '%' {
+			errno = ErrBadValByte
+			break
+		}
+
+		skip += 2
+		if iu+2 >= len(v) {
+			errno = ErrBadValHexLength
+			break
+		}
+		if c, err := hex.Decode(val[i:i+1], v[iu+1:iu+3]); err != nil {
+			if errors.As(err, new(hex.InvalidByteError)) {
+				errno = ErrBadValHexByte
+				break
+			}
+			// unreachable
+			panic(err.Error())
+		} else if c != 1 {
+			// unreachable
+			panic(fmt.Sprintf("invalid decode length %d", c))
+		}
+		i++
+		continue
+
+	opt:
+		val[i] = b
+		i++
+	}
+
+	return
+}
+
+type ParseError uint8
+
+func (e ParseError) Error() string {
+	switch e {
+	case errSuccess:
+		panic("attempted to return success as error")
+	case ErrNoColon:
+		return "address does not contain a colon"
+	case ErrBadPairSep:
+		return "'=' character not found"
+	case ErrBadPairKey:
+		return "'=' character has no key preceding it"
+	case ErrBadPairVal:
+		return "'=' character has no value following it"
+	case ErrBadValLength:
+		return "unescaped value has impossible length"
+	case ErrBadValByte:
+		return "in D-Bus address, characters other than [-0-9A-Za-z_/.\\*] should have been escaped"
+	case ErrBadValHexLength:
+		return "in D-Bus address, percent character was not followed by two hex digits"
+	case ErrBadValHexByte:
+		return "in D-Bus address, percent character was followed by characters other than hex digits"
+
+	default:
+		return fmt.Sprintf("parse error %d", e)
+	}
+}
+
+const (
+	errSuccess ParseError = iota
+	ErrNoColon
+	ErrBadPairSep
+	ErrBadPairKey
+	ErrBadPairVal
+	ErrBadValLength
+	ErrBadValByte
+	ErrBadValHexLength
+	ErrBadValHexByte
+)
+
+type BadAddressError struct {
+	// error type
+	Type ParseError
+
+	// bad entry position
+	EntryPos int
+	// bad entry value
+	EntryVal []byte
+
+	// bad pair position
+	PairPos int
+	// bad pair value
+	PairVal []byte
+}
+
+func (a *BadAddressError) Is(err error) bool {
+	var b *BadAddressError
+	return errors.As(err, &b) && a.Type == b.Type &&
+		a.EntryPos == b.EntryPos && slices.Equal(a.EntryVal, b.EntryVal) &&
+		a.PairPos == b.PairPos && slices.Equal(a.PairVal, b.PairVal)
+}
+
+func (a *BadAddressError) Error() string {
+	return a.Type.Error()
+}
+
+func (a *BadAddressError) Unwrap() error {
+	return a.Type
+}

dbus/address_escape_test.go

@@ -0,0 +1,55 @@
+package dbus
+
+import (
+	"testing"
+)
+
+func TestUnescapeValue(t *testing.T) {
+	testCases := []struct {
+		value   string
+		want    string
+		wantErr ParseError
+	}{
+		// upstream test cases
+		{value: "abcde", want: "abcde"},
+		{value: "", want: ""},
+		{value: "%20%20", want: "  "},
+		{value: "%24", want: "$"},
+		{value: "%25", want: "%"},
+		{value: "abc%24", want: "abc$"},
+		{value: "%24abc", want: "$abc"},
+		{value: "abc%24abc", want: "abc$abc"},
+		{value: "/", want: "/"},
+		{value: "-", want: "-"},
+		{value: "_", want: "_"},
+		{value: "A", want: "A"},
+		{value: "I", want: "I"},
+		{value: "Z", want: "Z"},
+		{value: "a", want: "a"},
+		{value: "i", want: "i"},
+		{value: "z", want: "z"},
+		/* Bug: https://bugs.freedesktop.org/show_bug.cgi?id=53499 */
+		{value: "%c3%b6", want: "\xc3\xb6"},
+
+		{value: "%a", wantErr: ErrBadValHexLength},
+		{value: "%q", wantErr: ErrBadValHexLength},
+		{value: "%az", wantErr: ErrBadValHexByte},
+		{value: "%%", wantErr: ErrBadValLength},
+		{value: "%$$", wantErr: ErrBadValHexByte},
+		{value: "abc%a", wantErr: ErrBadValHexLength},
+		{value: "%axyz", wantErr: ErrBadValHexByte},
+		{value: "%", wantErr: ErrBadValLength},
+		{value: "$", wantErr: ErrBadValByte},
+		{value: " ", wantErr: ErrBadValByte},
+	}
+
+	for _, tc := range testCases {
+		t.Run("unescape "+tc.value, func(t *testing.T) {
+			if got, errno := unescapeValue([]byte(tc.value)); errno != tc.wantErr {
+				t.Errorf("unescapeValue() errno = %v, wantErr %v", errno, tc.wantErr)
+			} else if tc.wantErr == errSuccess && string(got) != tc.want {
+				t.Errorf("unescapeValue() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}

dbus/address_test.go

@@ -0,0 +1,119 @@
+package dbus_test
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/dbus"
+)
+
+func TestParse(t *testing.T) {
+	testCases := []struct {
+		name    string
+		addr    string
+		want    []dbus.AddrEntry
+		wantErr error
+	}{
+		{
+			name: "simple session unix",
+			addr: "unix:path=/run/user/1971/bus",
+			want: []dbus.AddrEntry{{
+				Method: "unix",
+				Values: [][2]string{{"path", "/run/user/1971/bus"}},
+			}},
+		},
+		{
+			name: "simple upper escape",
+			addr: "debug:name=Test,cat=cute,escaped=%c3%b6",
+			want: []dbus.AddrEntry{{
+				Method: "debug",
+				Values: [][2]string{
+					{"name", "Test"},
+					{"cat", "cute"},
+					{"escaped", "\xc3\xb6"},
+				},
+			}},
+		},
+		{
+			name: "simple bad escape",
+			addr: "debug:name=%",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadValLength,
+				EntryPos: 0, EntryVal: []byte("debug:name=%"), PairPos: 0, PairVal: []byte("name=%")},
+		},
+
+		// upstream test cases
+		{
+			name: "full address success",
+			addr: "unix:path=/tmp/foo;debug:name=test,sliff=sloff;",
+			want: []dbus.AddrEntry{
+				{Method: "unix", Values: [][2]string{{"path", "/tmp/foo"}}},
+				{Method: "debug", Values: [][2]string{{"name", "test"}, {"sliff", "sloff"}}},
+			},
+		},
+		{
+			name: "empty address",
+			addr: "",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryVal: []byte{}, PairPos: -1},
+		},
+		{
+			name: "no body",
+			addr: "foo",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryPos: 0, EntryVal: []byte("foo"), PairPos: -1},
+		},
+		{
+			name: "no pair separator",
+			addr: "foo:bar",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar"), PairPos: 0, PairVal: []byte("bar")},
+		},
+		{
+			name: "no pair separator multi pair",
+			addr: "foo:bar,baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar,baz"), PairPos: 0, PairVal: []byte("bar")},
+		},
+		{
+			name: "no pair separator single valid pair",
+			addr: "foo:bar=foo,baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar=foo,baz"), PairPos: 1, PairVal: []byte("baz")},
+		},
+		{
+			name: "no body single valid address",
+			addr: "foo:bar=foo;baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryPos: 1, EntryVal: []byte("baz"), PairPos: -1},
+		},
+		{
+			name: "no key",
+			addr: "foo:=foo",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairKey,
+				EntryPos: 0, EntryVal: []byte("foo:=foo"), PairPos: 0, PairVal: []byte("=foo")},
+		},
+		{
+			name: "no value",
+			addr: "foo:foo=",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairVal,
+				EntryPos: 0, EntryVal: []byte("foo:foo="), PairPos: 0, PairVal: []byte("foo=")},
+		},
+		{
+			name: "no pair separator single valid pair trailing",
+			addr: "foo:foo,bar=baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:foo,bar=baz"), PairPos: 0, PairVal: []byte("foo")},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got, err := dbus.Parse([]byte(tc.addr)); !errors.Is(err, tc.wantErr) {
+				t.Errorf("Parse() error = %v, wantErr %v", err, tc.wantErr)
+			} else if tc.wantErr == nil && !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("Parse() = %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}

dbus/config_test.go

@@ -13,7 +13,7 @@ import (
 )
 
 func TestConfig_Args(t *testing.T) {
-	for _, tc := range testCases() {
+	for _, tc := range makeTestCases() {
 		if tc.wantErr {
 			// args does not check for nulls
 			continue
@@ -30,7 +30,7 @@ func TestConfig_Args(t *testing.T) {
 }
 
 func TestNewConfigFromFile(t *testing.T) {
-	for _, tc := range testCases() {
+	for _, tc := range makeTestCases() {
 		name := new(strings.Builder)
 		name.WriteString("parse configuration file for application ")
 		name.WriteString(tc.id)

dbus/samples_test.go

@@ -145,7 +145,7 @@ var (
 	testCaseOnce sync.Once
 )
 
-func testCases() []dbusTestCase {
+func makeTestCases() []dbusTestCase {
 	testCaseOnce.Do(testCaseGenerate)
 	return testCasesV
 }

fst/config.go

@@ -1,11 +1,7 @@
 package fst
 
 import (
-	"errors"
-
 	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/linux"
 	"git.gensokyo.uk/security/fortify/internal/system"
 )
 
@@ -49,37 +45,6 @@ type ConfinementConfig struct {
 	Enablements system.Enablements `json:"enablements"`
 }
 
-// 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"`
-	// 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"`
-
-	// 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"`
-}
-
 type ExtraPermConfig struct {
 	Ensure  bool   `json:"ensure,omitempty"`
 	Path    string `json:"path"`
@@ -121,102 +86,6 @@ type FilesystemConfig struct {
 	Must bool `json:"require,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) {
-	if s == nil {
-		return nil, errors.New("nil sandbox config")
-	}
-
-	var uid int
-	if !s.MapRealUID {
-		uid = 65534
-	} else {
-		uid = os.Geteuid()
-	}
-
-	conf := (&bwrap.Config{
-		Net:      s.Net,
-		UserNS:   s.UserNS,
-		Hostname: s.Hostname,
-		Clearenv: true,
-		SetEnv:   s.Env,
-
-		/* 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),
-
-		NewSession:    !s.NoNewSession,
-		DieWithParent: true,
-		AsInit:        true,
-
-		// initialise map
-		Chmod: make(bwrap.ChmodConfig),
-	}).
-		SetUID(uid).SetGID(uid).
-		Procfs("/proc").
-		Tmpfs(Tmp, 4*1024)
-
-	if !s.Dev {
-		conf.DevTmpfs("/dev").Mqueue("/dev/mqueue")
-	} else {
-		conf.Bind("/dev", "/dev", false, true, true)
-	}
-
-	if !s.AutoEtc {
-		if s.Etc == "" {
-			conf.Dir("/etc")
-		} else {
-			conf.Bind(s.Etc, "/etc")
-		}
-	}
-
-	for _, c := range s.Filesystem {
-		if c == nil {
-			continue
-		}
-		src := c.Src
-		dest := c.Dst
-		if c.Dst == "" {
-			dest = c.Src
-		}
-		conf.Bind(src, dest, !c.Must, c.Write, c.Device)
-	}
-
-	for _, l := range s.Link {
-		conf.Symlink(l[0], l[1])
-	}
-
-	if s.AutoEtc {
-		etc := s.Etc
-		if etc == "" {
-			etc = "/etc"
-		}
-		conf.Bind(etc, Tmp+"/etc")
-
-		// link host /etc contents to prevent passwd/group from being overwritten
-		if d, err := os.ReadDir(etc); err != nil {
-			return nil, err
-		} else {
-			for _, ent := range d {
-				name := ent.Name()
-				switch name {
-				case "passwd":
-				case "group":
-
-				case "mtab":
-					conf.Symlink("/proc/mounts", "/etc/"+name)
-				default:
-					conf.Symlink(Tmp+"/etc/"+name, "/etc/"+name)
-				}
-			}
-		}
-	}
-
-	return conf, nil
-}
-
 // Template returns a fully populated instance of Config.
 func Template() *Config {
 	return &Config{

fst/path.go

@@ -0,0 +1,11 @@
+package fst
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+func deepContainsH(basepath, targpath string) (bool, error) {
+	rel, err := filepath.Rel(basepath, targpath)
+	return err == nil && rel != ".." && !strings.HasPrefix(rel, string([]byte{'.', '.', filepath.Separator})), err
+}

fst/path_test.go

@@ -0,0 +1,85 @@
+package fst
+
+import (
+	"testing"
+)
+
+func TestDeepContainsH(t *testing.T) {
+	testCases := []struct {
+		name     string
+		basepath string
+		targpath string
+		want     bool
+		wantErr  bool
+	}{
+		{
+			name: "empty",
+			want: true,
+		},
+		{
+			name:     "equal abs",
+			basepath: "/run",
+			targpath: "/run",
+			want:     true,
+		},
+		{
+			name:     "equal rel",
+			basepath: "./run",
+			targpath: "run",
+			want:     true,
+		},
+		{
+			name:     "contains abs",
+			basepath: "/run",
+			targpath: "/run/dbus",
+			want:     true,
+		},
+		{
+			name:     "inverse contains abs",
+			basepath: "/run/dbus",
+			targpath: "/run",
+			want:     false,
+		},
+		{
+			name:     "contains rel",
+			basepath: "../run",
+			targpath: "../run/dbus",
+			want:     true,
+		},
+		{
+			name:     "inverse contains rel",
+			basepath: "../run/dbus",
+			targpath: "../run",
+			want:     false,
+		},
+		{
+			name:     "weird abs",
+			basepath: "/run/dbus",
+			targpath: "/run/dbus/../current-system",
+			want:     false,
+		},
+		{
+			name:     "weird rel",
+			basepath: "../run/dbus",
+			targpath: "../run/dbus/../current-system",
+			want:     false,
+		},
+
+		{
+			name:     "invalid mix",
+			basepath: "/run",
+			targpath: "./run",
+			wantErr:  true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got, err := deepContainsH(tc.basepath, tc.targpath); (err != nil) != tc.wantErr {
+				t.Errorf("deepContainsH() error = %v, wantErr %v", err, tc.wantErr)
+			} else if got != tc.want {
+				t.Errorf("deepContainsH() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}

fst/sandbox.go

@@ -0,0 +1,222 @@
+package fst
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"path"
+
+	"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"
+)
+
+// 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"`
+	// 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"`
+
+	// 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"`
+}
+
+// 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) {
+	if s == nil {
+		return nil, errors.New("nil sandbox config")
+	}
+
+	var uid int
+	if !s.MapRealUID {
+		uid = 65534
+	} else {
+		uid = os.Geteuid()
+	}
+
+	conf := (&bwrap.Config{
+		Net:      s.Net,
+		UserNS:   s.UserNS,
+		Hostname: s.Hostname,
+		Clearenv: true,
+		SetEnv:   s.Env,
+
+		/* 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),
+
+		NewSession:    !s.NoNewSession,
+		DieWithParent: true,
+		AsInit:        true,
+
+		// 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.Dev {
+		conf.DevTmpfs("/dev").Mqueue("/dev/mqueue")
+	} else {
+		conf.Bind("/dev", "/dev", false, true, true)
+	}
+
+	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
+	var hidePaths []string
+	sc := os.Paths()
+	hidePaths = append(hidePaths, sc.RuntimePath, sc.SharePath)
+	_, systemBusAddr := dbus.Address()
+	if entries, err := dbus.Parse([]byte(systemBusAddr)); err != nil {
+		return nil, err
+	} else {
+		// there is usually only one, do not preallocate
+		for _, entry := range entries {
+			if entry.Method != "unix" {
+				continue
+			}
+			for _, pair := range entry.Values {
+				if pair[0] == "path" {
+					if path.IsAbs(pair[1]) {
+						// 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])
+						}
+						hidePaths = append(hidePaths, dir)
+					} else {
+						fmsg.VPrintf("dbus socket %q is not absolute", pair[1])
+					}
+				}
+			}
+		}
+	}
+	hidePathMatch := make([]bool, len(hidePaths))
+	for i := range hidePaths {
+		if err := evalSymlinks(os, &hidePaths[i]); err != nil {
+			return nil, err
+		}
+	}
+
+	for _, c := range s.Filesystem {
+		if c == nil {
+			continue
+		}
+
+		if !path.IsAbs(c.Src) {
+			return 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)
+		}
+
+		srcH := c.Src
+		if err := evalSymlinks(os, &srcH); err != nil {
+			return nil, err
+		}
+
+		for i := range hidePaths {
+			// skip matched entries
+			if hidePathMatch[i] {
+				continue
+			}
+
+			if ok, err := deepContainsH(srcH, hidePaths[i]); err != nil {
+				return nil, err
+			} else if ok {
+				hidePathMatch[i] = true
+				fmsg.VPrintf("hiding paths from %q", c.Src)
+			}
+		}
+
+		conf.Bind(c.Src, dest, !c.Must, c.Write, c.Device)
+	}
+
+	// hide marked paths before setting up shares
+	for i, ok := range hidePathMatch {
+		if ok {
+			conf.Tmpfs(hidePaths[i], 8192)
+		}
+	}
+
+	for _, l := range s.Link {
+		conf.Symlink(l[0], l[1])
+	}
+
+	if s.AutoEtc {
+		etc := s.Etc
+		if etc == "" {
+			etc = "/etc"
+		}
+		conf.Bind(etc, Tmp+"/etc")
+
+		// link host /etc contents to prevent passwd/group from being overwritten
+		if d, err := os.ReadDir(etc); err != nil {
+			return nil, err
+		} else {
+			for _, ent := range d {
+				name := ent.Name()
+				switch name {
+				case "passwd":
+				case "group":
+
+				case "mtab":
+					conf.Symlink("/proc/mounts", "/etc/"+name)
+				default:
+					conf.Symlink(Tmp+"/etc/"+name, "/etc/"+name)
+				}
+			}
+		}
+	}
+
+	return conf, nil
+}
+
+func evalSymlinks(os linux.System, v *string) error {
+	if p, err := os.EvalSymlinks(*v); err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return err
+		}
+		fmsg.VPrintf("path %q does not yet exist", *v)
+	} else {
+		*v = p
+	}
+	return nil
+}

helper/bwrap.go

@@ -20,7 +20,7 @@ type bubblewrap struct {
 	name string
 
 	// bwrap pipes
-	p *pipes
+	control *pipes
 	// sync pipe
 	sync *os.File
 	// returns an array of arguments passed directly
@@ -29,7 +29,7 @@ type bubblewrap struct {
 
 	// pipes received by the child
 	// nil if no pipes are required
-	cp *pipes
+	controlPt *pipes
 
 	lock sync.RWMutex
 	*exec.Cmd
@@ -39,7 +39,7 @@ func (b *bubblewrap) StartNotify(ready chan error) error {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 
-	if ready != nil && b.cp == nil {
+	if ready != nil && b.controlPt == nil {
 		panic("attempted to start with status monitoring on a bwrap child initialised without pipes")
 	}
 
@@ -50,16 +50,16 @@ func (b *bubblewrap) StartNotify(ready chan error) error {
 	}
 
 	// prepare bwrap pipe and args
-	if argsFD, _, err := b.p.prepareCmd(b.Cmd); err != nil {
+	if argsFD, _, err := b.control.prepareCmd(b.Cmd); err != nil {
 		return err
 	} else {
 		b.Cmd.Args = append(b.Cmd.Args, "--args", strconv.Itoa(argsFD), "--", b.name)
 	}
 
 	// prepare child args and pipes if enabled
-	if b.cp != nil {
-		b.cp.ready = ready
-		if argsFD, statFD, err := b.cp.prepareCmd(b.Cmd); err != nil {
+	if b.controlPt != nil {
+		b.controlPt.ready = ready
+		if argsFD, statFD, err := b.controlPt.prepareCmd(b.Cmd); err != nil {
 			return err
 		} else {
 			b.Cmd.Args = append(b.Cmd.Args, b.argF(argsFD, statFD)...)
@@ -70,7 +70,7 @@ func (b *bubblewrap) StartNotify(ready chan error) error {
 
 	if ready != nil {
 		b.Cmd.Env = append(b.Cmd.Env, FortifyHelper+"=1", FortifyStatus+"=1")
-	} else if b.cp != nil {
+	} else if b.controlPt != nil {
 		b.Cmd.Env = append(b.Cmd.Env, FortifyHelper+"=1", FortifyStatus+"=0")
 	} else {
 		b.Cmd.Env = append(b.Cmd.Env, FortifyHelper+"=1", FortifyStatus+"=-1")
@@ -85,13 +85,13 @@ func (b *bubblewrap) StartNotify(ready chan error) error {
 	}
 
 	// write bwrap args first
-	if err := b.p.readyWriteArgs(); err != nil {
+	if err := b.control.readyWriteArgs(); err != nil {
 		return err
 	}
 
 	// write child args if enabled
-	if b.cp != nil {
-		if err := b.cp.readyWriteArgs(); err != nil {
+	if b.controlPt != nil {
+		if err := b.controlPt.readyWriteArgs(); err != nil {
 			return err
 		}
 	}
@@ -100,11 +100,11 @@ func (b *bubblewrap) StartNotify(ready chan error) error {
 }
 
 func (b *bubblewrap) Close() error {
-	if b.cp == nil {
+	if b.controlPt == nil {
 		panic("attempted to close bwrap child initialised without pipes")
 	}
 
-	return b.cp.closeStatus()
+	return b.controlPt.closeStatus()
 }
 
 func (b *bubblewrap) Start() error {
@@ -136,14 +136,14 @@ func NewBwrap(conf *bwrap.Config, wt io.WriterTo, name string, argF func(argsFD,
 	if args, err := NewCheckedArgs(conf.Args()); err != nil {
 		return nil, err
 	} else {
-		b.p = &pipes{args: args}
+		b.control = &pipes{args: args}
 	}
 
 	b.sync = conf.Sync()
 	b.argF = argF
 	b.name = name
 	if wt != nil {
-		b.cp = &pipes{args: wt}
+		b.controlPt = &pipes{args: wt}
 	}
 	b.Cmd = execCommand(BubblewrapName)
 

helper/bwrap/arg.static.awkward.go

@@ -1,23 +0,0 @@
-package bwrap
-
-const (
-	Tmpfs = iota
-	Dir
-	Symlink
-
-	OverlaySrc
-	Overlay
-	TmpOverlay
-	ROOverlay
-)
-
-var awkwardArgs = [...]string{
-	Tmpfs:   "--tmpfs",
-	Dir:     "--dir",
-	Symlink: "--symlink",
-
-	OverlaySrc: "--overlay-src",
-	Overlay:    "--overlay",
-	TmpOverlay: "--tmp-overlay",
-	ROOverlay:  "--ro-overlay",
-}

helper/bwrap/arg.static.bool.go

@@ -1,81 +0,0 @@
-package bwrap
-
-const (
-	UnshareAll = 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, boolArgs[i]...)
-		}
-	}
-}

helper/bwrap/arg.static.int.go

@@ -1,47 +0,0 @@
-package bwrap
-
-import "strconv"
-
-const (
-	UID = iota
-	GID
-	Perms
-	Size
-)
-
-var intArgs = [...]string{
-	UID:   "--uid",
-	GID:   "--gid",
-	Perms: "--perms",
-	Size:  "--size",
-}
-
-func (c *Config) intArgs() Builder {
-	// Arg types:
-	//   Perms
-	// are handled by the sequential 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, intArgs[i], strconv.Itoa(*v))
-		}
-	}
-}

helper/bwrap/arg.static.pair.go

@@ -1,73 +0,0 @@
-package bwrap
-
-import (
-	"slices"
-)
-
-const (
-	SetEnv = iota
-
-	Bind
-	BindTry
-	DevBind
-	DevBindTry
-	ROBind
-	ROBindTry
-
-	Chmod
-)
-
-var pairArgs = [...]string{
-	SetEnv: "--setenv",
-
-	Bind:       "--bind",
-	BindTry:    "--bind-try",
-	DevBind:    "--dev-bind",
-	DevBindTry: "--dev-bind-try",
-	ROBind:     "--ro-bind",
-	ROBindTry:  "--ro-bind-try",
-
-	Chmod: "--chmod",
-}
-
-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]}
-	}
-
-	// Arg types:
-	//   Bind
-	//   BindTry
-	//   DevBind
-	//   DevBindTry
-	//   ROBind
-	//   ROBindTry
-	//   Chmod
-	// are handled by the sequential builder
-
-	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, pairArgs[i], v[0], v[1])
-		}
-	}
-}

helper/bwrap/arg.static.string.go

@@ -1,65 +0,0 @@
-package bwrap
-
-const (
-	Hostname = iota
-	Chdir
-	UnsetEnv
-	LockFile
-
-	RemountRO
-	Procfs
-	DevTmpfs
-	Mqueue
-)
-
-var stringArgs = [...]string{
-	Hostname: "--hostname",
-	Chdir:    "--chdir",
-	UnsetEnv: "--unsetenv",
-	LockFile: "--lock-file",
-
-	RemountRO: "--remount-ro",
-	Procfs:    "--proc",
-	DevTmpfs:  "--dev",
-	Mqueue:    "--mqueue",
-}
-
-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}
-	}
-
-	// Arg types:
-	// 	 RemountRO
-	//   Procfs
-	//   DevTmpfs
-	//   Mqueue
-	// are handled by the sequential builder
-
-	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, stringArgs[i], v)
-		}
-	}
-}

helper/bwrap/builder.go

@@ -39,46 +39,60 @@ func (c *Config) Bind(src, dest string, opts ...bool) *Config {
 
 	if dev {
 		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[DevBindTry], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{DevBindTry.Unwrap(), src, dest})
 		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[DevBind], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{DevBind.Unwrap(), src, dest})
 		}
 		return c
 	} else if write {
 		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[BindTry], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{BindTry.Unwrap(), src, dest})
 		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[Bind], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{Bind.Unwrap(), src, dest})
 		}
 		return c
 	} else {
 		if try {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[ROBindTry], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{ROBindTry.Unwrap(), src, dest})
 		} else {
-			c.Filesystem = append(c.Filesystem, &pairF{pairArgs[ROBind], src, dest})
+			c.Filesystem = append(c.Filesystem, &pairF{ROBind.Unwrap(), src, dest})
 		}
 		return c
 	}
 }
 
+// Dir create dir in sandbox
+// (--dir DEST)
+func (c *Config) Dir(dest string) *Config {
+	c.Filesystem = append(c.Filesystem, &stringF{Dir.Unwrap(), 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{stringArgs[RemountRO], dest})
+	c.Filesystem = append(c.Filesystem, &stringF{RemountRO.Unwrap(), dest})
 	return c
 }
 
 // Procfs mount new procfs in sandbox
 // (--proc DEST)
 func (c *Config) Procfs(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{stringArgs[Procfs], dest})
+	c.Filesystem = append(c.Filesystem, &stringF{Procfs.Unwrap(), dest})
 	return c
 }
 
 // DevTmpfs mount new dev in sandbox
 // (--dev DEST)
 func (c *Config) DevTmpfs(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{stringArgs[DevTmpfs], dest})
+	c.Filesystem = append(c.Filesystem, &stringF{DevTmpfs.Unwrap(), 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.Unwrap(), dest})
 	return c
 }
 
@@ -121,20 +135,6 @@ func (c *Config) Persist(dest, rwsrc, workdir string, src ...string) *Config {
 	return c
 }
 
-// Mqueue mount new mqueue in sandbox
-// (--mqueue DEST)
-func (c *Config) Mqueue(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{stringArgs[Mqueue], dest})
-	return c
-}
-
-// Dir create dir in sandbox
-// (--dir DEST)
-func (c *Config) Dir(dest string) *Config {
-	c.Filesystem = append(c.Filesystem, &stringF{awkwardArgs[Dir], dest})
-	return c
-}
-
 // Symlink create symlink within sandbox
 // (--symlink SRC DEST)
 func (c *Config) Symlink(src, dest string, perm ...os.FileMode) *Config {

helper/bwrap/config.go

@@ -1,16 +1,9 @@
 package bwrap
 
 import (
-	"encoding/gob"
 	"os"
-	"strconv"
 )
 
-func init() {
-	gob.Register(new(PermConfig[SymlinkConfig]))
-	gob.Register(new(PermConfig[*TmpfsConfig]))
-}
-
 type Config struct {
 	// unshare every namespace we support by default if nil
 	// (--unshare-all)
@@ -123,153 +116,3 @@ type UnshareConfig struct {
 	// create new cgroup namespace
 	CGroup bool `json:"cgroup"`
 }
-
-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, intArgs[Perms], 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, intArgs[Size], strconv.Itoa(t.Size))
-	}
-	*args = append(*args, awkwardArgs[Tmpfs], 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, awkwardArgs[OverlaySrc], src)
-	}
-
-	if o.Persist != nil {
-		if o.Persist[0] != "" && o.Persist[1] != "" {
-			// --overlay RWSRC WORKDIR
-			*args = append(*args, awkwardArgs[Overlay], o.Persist[0], o.Persist[1])
-		} else {
-			// --ro-overlay
-			*args = append(*args, awkwardArgs[ROOverlay])
-		}
-	} else {
-		// --tmp-overlay
-		*args = append(*args, awkwardArgs[TmpOverlay])
-	}
-
-	// 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, awkwardArgs[Symlink], 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, pairArgs[Chmod], strconv.FormatInt(int64(mode), 8), path)
-	}
-}

helper/bwrap/config_test.go

@@ -1,6 +1,7 @@
 package bwrap_test
 
 import (
+	"os"
 	"slices"
 	"testing"
 
@@ -13,6 +14,83 @@ func TestConfig_Args(t *testing.T) {
 		conf *bwrap.Config
 		want []string
 	}{
+		{
+			name: "bind",
+			conf: (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),
+			want: []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",
+			},
+		},
+		{
+			name: "dir remount-ro proc dev mqueue",
+			conf: (new(bwrap.Config)).
+				Dir("/.fortify").
+				RemountRO("/home").
+				Procfs("/proc").
+				DevTmpfs("/dev").
+				Mqueue("/dev/mqueue"),
+			want: []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",
+			},
+		},
+		{
+			name: "tmpfs",
+			conf: (new(bwrap.Config)).
+				Tmpfs("/run/user", 8192).
+				Tmpfs("/run/dbus", 8192, 0755),
+			want: []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",
+			},
+		},
+		{
+			name: "symlink",
+			conf: (new(bwrap.Config)).
+				Symlink("/.fortify/sbin/init", "/sbin/init").
+				Symlink("/.fortify/sbin/init", "/sbin/init", 0755),
+			want: []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",
+			},
+		},
 		{
 			name: "overlayfs",
 			conf: (new(bwrap.Config)).
@@ -32,6 +110,64 @@ func TestConfig_Args(t *testing.T) {
 				"--overlay", "/data/data/org.chromium.Chromium/overlay/rwsrc", "/data/data/org.chromium.Chromium/workdir", "/nix",
 			},
 		},
+		{
+			name: "unshare",
+			conf: &bwrap.Config{Unshare: &bwrap.UnshareConfig{
+				User:   false,
+				IPC:    false,
+				PID:    false,
+				Net:    false,
+				UTS:    false,
+				CGroup: false,
+			}},
+			want: []string{"--disable-userns", "--assert-userns-disabled"},
+		},
+		{
+			name: "uid gid sync",
+			conf: (new(bwrap.Config)).
+				SetUID(1971).
+				SetGID(100).
+				SetSync(os.Stdin),
+			want: []string{
+				"--unshare-all", "--unshare-user",
+				"--disable-userns", "--assert-userns-disabled",
+				// SetUID(1971)
+				"--uid", "1971",
+				// SetGID(100)
+				"--gid", "100",
+				// SetSync(os.Stdin)
+				// this is set when the process is created
+			},
+		},
+		{
+			name: "hostname chdir setenv unsetenv lockfile chmod",
+			conf: &bwrap.Config{
+				Hostname: "fortify",
+				Chdir:    "/.fortify",
+				SetEnv:   map[string]string{"FORTIFY_INIT": "/.fortify/sbin/init"},
+				UnsetEnv: []string{"HOME", "HOST"},
+				LockFile: []string{"/.fortify/lock"},
+				Chmod:    map[string]os.FileMode{"/.fortify/sbin/init": 0755},
+			},
+			want: []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",
+				// Chmod: map[string]os.FileMode{"/.fortify/sbin/init": 0755}
+				"--chmod", "755", "/.fortify/sbin/init",
+			},
+		},
+
 		{
 			name: "xdg-dbus-proxy constraint sample",
 			conf: (&bwrap.Config{
@@ -90,148 +226,6 @@ func TestConfig_Args(t *testing.T) {
 				"--ro-bind", "/etc", "/etc",
 			},
 		},
-		{
-			name: "fortify permissive default nixos",
-			conf: (&bwrap.Config{
-				Unshare:  nil,
-				Net:      true,
-				UserNS:   true,
-				Clearenv: true,
-				SetEnv: map[string]string{
-					"HOME":              "/home/chronos",
-					"TERM":              "xterm-256color",
-					"FORTIFY_INIT":      "3",
-					"XDG_RUNTIME_DIR":   "/run/user/150",
-					"XDG_SESSION_CLASS": "user",
-					"XDG_SESSION_TYPE":  "tty",
-					"SHELL":             "/run/current-system/sw/bin/zsh",
-					"USER":              "chronos",
-				},
-				DieWithParent: true,
-				AsInit:        true,
-			}).SetUID(65534).SetGID(65534).
-				Procfs("/proc").DevTmpfs("/dev").Mqueue("/dev/mqueue").
-				Bind("/bin", "/bin", false, true).
-				Bind("/boot", "/boot", false, true).
-				Bind("/etc", "/etc", 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("/srv", "/srv", false, true).
-				Bind("/sys", "/sys", false, true).
-				Bind("/usr", "/usr", false, true).
-				Bind("/var", "/var", false, true).
-				Bind("/run/NetworkManager", "/run/NetworkManager", false, true).
-				Bind("/run/agetty.reload", "/run/agetty.reload", false, true).
-				Bind("/run/binfmt", "/run/binfmt", false, true).
-				Bind("/run/booted-system", "/run/booted-system", false, true).
-				Bind("/run/credentials", "/run/credentials", false, true).
-				Bind("/run/cryptsetup", "/run/cryptsetup", false, true).
-				Bind("/run/current-system", "/run/current-system", false, true).
-				Bind("/run/host", "/run/host", false, true).
-				Bind("/run/keys", "/run/keys", false, true).
-				Bind("/run/libvirt", "/run/libvirt", false, true).
-				Bind("/run/libvirtd.pid", "/run/libvirtd.pid", false, true).
-				Bind("/run/lock", "/run/lock", false, true).
-				Bind("/run/log", "/run/log", false, true).
-				Bind("/run/lvm", "/run/lvm", false, true).
-				Bind("/run/mount", "/run/mount", false, true).
-				Bind("/run/nginx", "/run/nginx", false, true).
-				Bind("/run/nscd", "/run/nscd", false, true).
-				Bind("/run/opengl-driver", "/run/opengl-driver", false, true).
-				Bind("/run/pppd", "/run/pppd", false, true).
-				Bind("/run/resolvconf", "/run/resolvconf", false, true).
-				Bind("/run/sddm", "/run/sddm", false, true).
-				Bind("/run/syncoid", "/run/syncoid", false, true).
-				Bind("/run/systemd", "/run/systemd", false, true).
-				Bind("/run/tmpfiles.d", "/run/tmpfiles.d", false, true).
-				Bind("/run/udev", "/run/udev", false, true).
-				Bind("/run/udisks2", "/run/udisks2", false, true).
-				Bind("/run/utmp", "/run/utmp", false, true).
-				Bind("/run/virtlogd.pid", "/run/virtlogd.pid", false, true).
-				Bind("/run/wrappers", "/run/wrappers", false, true).
-				Bind("/run/zed.pid", "/run/zed.pid", false, true).
-				Bind("/run/zed.state", "/run/zed.state", false, true).
-				Bind("/tmp/fortify.1971/tmpdir/150", "/tmp", false, true).
-				Tmpfs("/tmp/fortify.1971", 1048576).
-				Tmpfs("/run/user", 1048576).
-				Tmpfs("/run/user/150", 8388608).
-				Bind("/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd").
-				Bind("/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group").
-				Bind("/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd", "/etc/passwd").
-				Bind("/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group", "/etc/group").
-				Tmpfs("/var/run/nscd", 8192),
-			want: []string{
-				"--unshare-all", "--unshare-user", "--share-net",
-				"--clearenv", "--die-with-parent", "--as-pid-1",
-				"--uid", "65534",
-				"--gid", "65534",
-				"--setenv", "FORTIFY_INIT", "3",
-				"--setenv", "HOME", "/home/chronos",
-				"--setenv", "SHELL", "/run/current-system/sw/bin/zsh",
-				"--setenv", "TERM", "xterm-256color",
-				"--setenv", "USER", "chronos",
-				"--setenv", "XDG_RUNTIME_DIR", "/run/user/150",
-				"--setenv", "XDG_SESSION_CLASS", "user",
-				"--setenv", "XDG_SESSION_TYPE", "tty",
-				"--proc", "/proc", "--dev", "/dev",
-				"--mqueue", "/dev/mqueue",
-				"--bind", "/bin", "/bin",
-				"--bind", "/boot", "/boot",
-				"--bind", "/etc", "/etc",
-				"--bind", "/home", "/home",
-				"--bind", "/lib", "/lib",
-				"--bind", "/lib64", "/lib64",
-				"--bind", "/nix", "/nix",
-				"--bind", "/root", "/root",
-				"--bind", "/srv", "/srv",
-				"--bind", "/sys", "/sys",
-				"--bind", "/usr", "/usr",
-				"--bind", "/var", "/var",
-				"--bind", "/run/NetworkManager", "/run/NetworkManager",
-				"--bind", "/run/agetty.reload", "/run/agetty.reload",
-				"--bind", "/run/binfmt", "/run/binfmt",
-				"--bind", "/run/booted-system", "/run/booted-system",
-				"--bind", "/run/credentials", "/run/credentials",
-				"--bind", "/run/cryptsetup", "/run/cryptsetup",
-				"--bind", "/run/current-system", "/run/current-system",
-				"--bind", "/run/host", "/run/host",
-				"--bind", "/run/keys", "/run/keys",
-				"--bind", "/run/libvirt", "/run/libvirt",
-				"--bind", "/run/libvirtd.pid", "/run/libvirtd.pid",
-				"--bind", "/run/lock", "/run/lock",
-				"--bind", "/run/log", "/run/log",
-				"--bind", "/run/lvm", "/run/lvm",
-				"--bind", "/run/mount", "/run/mount",
-				"--bind", "/run/nginx", "/run/nginx",
-				"--bind", "/run/nscd", "/run/nscd",
-				"--bind", "/run/opengl-driver", "/run/opengl-driver",
-				"--bind", "/run/pppd", "/run/pppd",
-				"--bind", "/run/resolvconf", "/run/resolvconf",
-				"--bind", "/run/sddm", "/run/sddm",
-				"--bind", "/run/syncoid", "/run/syncoid",
-				"--bind", "/run/systemd", "/run/systemd",
-				"--bind", "/run/tmpfiles.d", "/run/tmpfiles.d",
-				"--bind", "/run/udev", "/run/udev",
-				"--bind", "/run/udisks2", "/run/udisks2",
-				"--bind", "/run/utmp", "/run/utmp",
-				"--bind", "/run/virtlogd.pid", "/run/virtlogd.pid",
-				"--bind", "/run/wrappers", "/run/wrappers",
-				"--bind", "/run/zed.pid", "/run/zed.pid",
-				"--bind", "/run/zed.state", "/run/zed.state",
-				"--bind", "/tmp/fortify.1971/tmpdir/150", "/tmp",
-				"--size", "1048576", "--tmpfs", "/tmp/fortify.1971",
-				"--size", "1048576", "--tmpfs", "/run/user",
-				"--size", "8388608", "--tmpfs", "/run/user/150",
-				"--ro-bind", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd",
-				"--ro-bind", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group",
-				"--ro-bind", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/passwd", "/etc/passwd",
-				"--ro-bind", "/tmp/fortify.1971/67a97cc824a64ef789f16b20ca6ce311/group", "/etc/group",
-				"--size", "8192", "--tmpfs", "/var/run/nscd",
-			},
-		},
 	}
 
 	for _, tc := range testCases {
@@ -241,4 +235,21 @@ func TestConfig_Args(t *testing.T) {
 			}
 		})
 	}
+
+	// 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", "", "")
+	})
+
+	t.Run("sync file", func(t *testing.T) {
+		if s := (new(bwrap.Config)).SetSync(os.Stdout).Sync(); s != os.Stdout {
+			t.Errorf("Sync() = %v", s)
+		}
+	})
 }

helper/bwrap/sequential.go

@@ -0,0 +1,223 @@
+package bwrap
+
+import (
+	"encoding/gob"
+	"os"
+	"strconv"
+)
+
+func init() {
+	gob.Register(new(PermConfig[SymlinkConfig]))
+	gob.Register(new(PermConfig[*TmpfsConfig]))
+	gob.Register(new(OverlayConfig))
+}
+
+type PositionalArg int
+
+func (p PositionalArg) Unwrap() 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
+)
+
+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",
+}
+
+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.Unwrap(), 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.Unwrap(), strconv.Itoa(t.Size))
+	}
+	*args = append(*args, Tmpfs.Unwrap(), 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.Unwrap(), src)
+	}
+
+	if o.Persist != nil {
+		if o.Persist[0] != "" && o.Persist[1] != "" {
+			// --overlay RWSRC WORKDIR
+			*args = append(*args, Overlay.Unwrap(), o.Persist[0], o.Persist[1])
+		} else {
+			// --ro-overlay
+			*args = append(*args, ROOverlay.Unwrap())
+		}
+	} else {
+		// --tmp-overlay
+		*args = append(*args, TmpOverlay.Unwrap())
+	}
+
+	// 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.Unwrap(), 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.Unwrap(), strconv.FormatInt(int64(mode), 8), path)
+	}
+}

helper/bwrap/static.go

@@ -0,0 +1,249 @@
+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])
+		}
+	}
+}

internal/app/app_pd_test.go

@@ -62,45 +62,14 @@ var testCasesPd = []sealTestCase{
 			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("/run/agetty.reload", "/run/agetty.reload", false, true).
-			Bind("/run/binfmt", "/run/binfmt", false, true).
-			Bind("/run/booted-system", "/run/booted-system", false, true).
-			Bind("/run/credentials", "/run/credentials", false, true).
-			Bind("/run/cryptsetup", "/run/cryptsetup", false, true).
-			Bind("/run/current-system", "/run/current-system", false, true).
-			Bind("/run/host", "/run/host", false, true).
-			Bind("/run/keys", "/run/keys", false, true).
-			Bind("/run/libvirt", "/run/libvirt", false, true).
-			Bind("/run/libvirtd.pid", "/run/libvirtd.pid", false, true).
-			Bind("/run/lock", "/run/lock", false, true).
-			Bind("/run/log", "/run/log", false, true).
-			Bind("/run/lvm", "/run/lvm", false, true).
-			Bind("/run/mount", "/run/mount", false, true).
-			Bind("/run/NetworkManager", "/run/NetworkManager", false, true).
-			Bind("/run/nginx", "/run/nginx", false, true).
-			Bind("/run/nixos", "/run/nixos", false, true).
-			Bind("/run/nscd", "/run/nscd", false, true).
-			Bind("/run/opengl-driver", "/run/opengl-driver", false, true).
-			Bind("/run/pppd", "/run/pppd", false, true).
-			Bind("/run/resolvconf", "/run/resolvconf", false, true).
-			Bind("/run/sddm", "/run/sddm", false, true).
-			Bind("/run/store", "/run/store", false, true).
-			Bind("/run/syncoid", "/run/syncoid", false, true).
-			Bind("/run/system", "/run/system", false, true).
-			Bind("/run/systemd", "/run/systemd", false, true).
-			Bind("/run/tmpfiles.d", "/run/tmpfiles.d", false, true).
-			Bind("/run/udev", "/run/udev", false, true).
-			Bind("/run/udisks2", "/run/udisks2", false, true).
-			Bind("/run/utmp", "/run/utmp", false, true).
-			Bind("/run/virtlogd.pid", "/run/virtlogd.pid", false, true).
-			Bind("/run/wrappers", "/run/wrappers", false, true).
-			Bind("/run/zed.pid", "/run/zed.pid", false, true).
-			Bind("/run/zed.state", "/run/zed.state", 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").
@@ -317,46 +286,15 @@ var testCasesPd = []sealTestCase{
 			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("/run/agetty.reload", "/run/agetty.reload", false, true).
-			Bind("/run/binfmt", "/run/binfmt", false, true).
-			Bind("/run/booted-system", "/run/booted-system", false, true).
-			Bind("/run/credentials", "/run/credentials", false, true).
-			Bind("/run/cryptsetup", "/run/cryptsetup", false, true).
-			Bind("/run/current-system", "/run/current-system", false, true).
-			Bind("/run/host", "/run/host", false, true).
-			Bind("/run/keys", "/run/keys", false, true).
-			Bind("/run/libvirt", "/run/libvirt", false, true).
-			Bind("/run/libvirtd.pid", "/run/libvirtd.pid", false, true).
-			Bind("/run/lock", "/run/lock", false, true).
-			Bind("/run/log", "/run/log", false, true).
-			Bind("/run/lvm", "/run/lvm", false, true).
-			Bind("/run/mount", "/run/mount", false, true).
-			Bind("/run/NetworkManager", "/run/NetworkManager", false, true).
-			Bind("/run/nginx", "/run/nginx", false, true).
-			Bind("/run/nixos", "/run/nixos", false, true).
-			Bind("/run/nscd", "/run/nscd", false, true).
-			Bind("/run/opengl-driver", "/run/opengl-driver", false, true).
-			Bind("/run/pppd", "/run/pppd", false, true).
-			Bind("/run/resolvconf", "/run/resolvconf", false, true).
-			Bind("/run/sddm", "/run/sddm", false, true).
-			Bind("/run/store", "/run/store", false, true).
-			Bind("/run/syncoid", "/run/syncoid", false, true).
-			Bind("/run/system", "/run/system", false, true).
-			Bind("/run/systemd", "/run/systemd", false, true).
-			Bind("/run/tmpfiles.d", "/run/tmpfiles.d", false, true).
-			Bind("/run/udev", "/run/udev", false, true).
-			Bind("/run/udisks2", "/run/udisks2", false, true).
-			Bind("/run/utmp", "/run/utmp", false, true).
-			Bind("/run/virtlogd.pid", "/run/virtlogd.pid", false, true).
-			Bind("/run/wrappers", "/run/wrappers", false, true).
-			Bind("/run/zed.pid", "/run/zed.pid", false, true).
-			Bind("/run/zed.state", "/run/zed.state", 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").

internal/app/app_stub_test.go

@@ -2,7 +2,6 @@ package app_test
 
 import (
 	"fmt"
-	"io"
 	"io/fs"
 	"os/user"
 	"strconv"
@@ -128,12 +127,12 @@ func (s *stubNixOS) Open(name string) (fs.File, error) {
 	}
 }
 
-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) Stdout() io.Writer {
-	panic("requested stdout")
+func (s *stubNixOS) Exit(code int) {
+	panic("called exit on stub with code " + strconv.Itoa(code))
 }
 
 func (s *stubNixOS) Paths() linux.Paths {

internal/app/app_test.go

@@ -1,6 +1,7 @@
 package app_test
 
 import (
+	"encoding/json"
 	"io/fs"
 	"reflect"
 	"testing"
@@ -48,14 +49,22 @@ func TestApp(t *testing.T) {
 
 			t.Run("compare bwrap", func(t *testing.T) {
 				if !reflect.DeepEqual(gotBwrap, tc.wantBwrap) {
-					t.Errorf("seal: bwrap = %#v, want %#v",
-						gotBwrap, tc.wantBwrap)
+					t.Errorf("seal: bwrap =\n%s\n, want\n%s",
+						mustMarshal(gotBwrap), mustMarshal(tc.wantBwrap))
 				}
 			})
 		})
 	}
 }
 
+func mustMarshal(v any) string {
+	if b, err := json.Marshal(v); err != nil {
+		panic(err.Error())
+	} else {
+		return string(b)
+	}
+}
+
 func stubDirEntries(names ...string) (e []fs.DirEntry, err error) {
 	e = make([]fs.DirEntry, len(names))
 	for i, name := range names {

internal/app/seal.go

@@ -194,7 +194,6 @@ func (a *app) Seal(config *fst.Config) error {
 				switch p {
 				case "/proc":
 				case "/dev":
-				case "/run":
 				case "/tmp":
 				case "/mnt":
 				case "/etc":
@@ -205,23 +204,7 @@ func (a *app) Seal(config *fst.Config) error {
 			}
 			conf.Filesystem = append(conf.Filesystem, b...)
 		}
-		// bind entries in /run
-		if d, err := a.os.ReadDir("/run"); err != nil {
-			return err
-		} else {
-			b := make([]*fst.FilesystemConfig, 0, len(d))
-			for _, ent := range d {
-				name := ent.Name()
-				switch name {
-				case "user":
-				case "dbus":
-				default:
-					p := "/run/" + name
-					b = append(b, &fst.FilesystemConfig{Src: p, Write: true, Must: true})
-				}
-			}
-			conf.Filesystem = append(conf.Filesystem, b...)
-		}
+
 		// hide nscd from sandbox if present
 		nscd := "/var/run/nscd"
 		if _, err := a.os.Stat(nscd); !errors.Is(err, fs.ErrNotExist) {

internal/linux/interface.go

@@ -1,7 +1,6 @@
 package linux
 
 import (
-	"io"
 	"io/fs"
 	"os/user"
 	"path"
@@ -30,10 +29,10 @@ type System interface {
 	Stat(name string) (fs.FileInfo, error)
 	// Open provides [os.Open]
 	Open(name string) (fs.File, error)
+	// EvalSymlinks provides [filepath.EvalSymlinks]
+	EvalSymlinks(path string) (string, error)
 	// Exit provides [os.Exit].
 	Exit(code int)
-	// Stdout provides [os.Stdout].
-	Stdout() io.Writer
 
 	// Paths returns a populated [Paths] struct.
 	Paths() Paths

internal/linux/std.go

@@ -2,11 +2,11 @@ package linux
 
 import (
 	"errors"
-	"io"
 	"io/fs"
 	"os"
 	"os/exec"
 	"os/user"
+	"path/filepath"
 	"strconv"
 	"sync"
 	"syscall"
@@ -37,8 +37,8 @@ func (s *Std) LookupGroup(name string) (*user.Group, error) { return user.Lookup
 func (s *Std) ReadDir(name string) ([]os.DirEntry, error)   { return os.ReadDir(name) }
 func (s *Std) Stat(name string) (fs.FileInfo, error)        { return os.Stat(name) }
 func (s *Std) Open(name string) (fs.File, error)            { return os.Open(name) }
+func (s *Std) EvalSymlinks(path string) (string, error)     { return filepath.EvalSymlinks(path) }
 func (s *Std) Exit(code int)                                { fmsg.Exit(code) }
-func (s *Std) Stdout() io.Writer                            { return os.Stdout }
 
 const xdgRuntimeDir = "XDG_RUNTIME_DIR"