sandbox: set mkdir perm

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

sandbox/container_test.go

@@ -93,7 +93,7 @@ func TestContainer(t *testing.T) {
 			container.
 				Tmpfs("/tmp", 0, 0755).
 				Bind(os.Args[0], os.Args[0], 0).
-				Mkdir("/usr/bin").
+				Mkdir("/usr/bin", 0755).
 				Link(os.Args[0], "/usr/bin/sandbox.test").
 				Place("/etc/hostname", []byte(container.Args[5]))
 			// in case test has cgo enabled

sandbox/mount.go

@@ -101,7 +101,7 @@ func remountWithFlags(n *vfs.MountInfoNode, mf uintptr) error {
 
 func mountTmpfs(fsname, name string, size int, perm os.FileMode) error {
 	target := toSysroot(name)
-	if err := os.MkdirAll(target, perm); err != nil {
+	if err := os.MkdirAll(target, parentPerm(perm)); err != nil {
 		return msg.WrapErr(err, err.Error())
 	}
 	opt := fmt.Sprintf("mode=%#o", perm)
@@ -112,3 +112,14 @@ func mountTmpfs(fsname, name string, size int, perm os.FileMode) error {
 		syscall.MS_NOSUID|syscall.MS_NODEV, opt),
 		fmt.Sprintf("cannot mount tmpfs on %q:", name))
 }
+
+func parentPerm(perm os.FileMode) os.FileMode {
+	pperm := 0755
+	if perm&0070 == 0 {
+		pperm &= ^0050
+	}
+	if perm&0007 == 0 {
+		pperm &= ^0005
+	}
+	return os.FileMode(pperm)
+}

sandbox/path.go

@@ -30,8 +30,8 @@ func toHost(name string) string {
 	return path.Join(hostPath, name)
 }
 
-func createFile(name string, perm os.FileMode, content []byte) error {
-	if err := os.MkdirAll(path.Dir(name), 0755); err != nil {
+func createFile(name string, perm, pperm os.FileMode, content []byte) error {
+	if err := os.MkdirAll(path.Dir(name), pperm); err != nil {
 		return msg.WrapErr(err, err.Error())
 	}
 	f, err := os.OpenFile(name, syscall.O_CREAT|syscall.O_EXCL|syscall.O_WRONLY, perm)
@@ -47,13 +47,13 @@ func createFile(name string, perm os.FileMode, content []byte) error {
 	return errors.Join(f.Close(), err)
 }
 
-func ensureFile(name string, perm os.FileMode) error {
+func ensureFile(name string, perm, pperm os.FileMode) error {
 	fi, err := os.Stat(name)
 	if err != nil {
 		if !os.IsNotExist(err) {
 			return err
 		}
-		return createFile(name, perm, nil)
+		return createFile(name, perm, pperm, nil)
 	}
 
 	if mode := fi.Mode(); mode&fs.ModeDir != 0 || mode&fs.ModeSymlink != 0 {

sandbox/sequential.go

@@ -61,13 +61,16 @@ func (b *BindMount) apply(*Params) error {
 
 	source := toHost(b.SourceFinal)
 	target := toSysroot(b.Target)
+
+	// this perm value emulates bwrap behaviour as it clears bits from 0755 based on
+	// op->perms which is never set for any bind setup op so always results in 0700
 	if fi, err := os.Stat(source); err != nil {
 		return msg.WrapErr(err, err.Error())
 	} else if fi.IsDir() {
-		if err = os.MkdirAll(target, 0755); err != nil {
+		if err = os.MkdirAll(target, 0700); err != nil {
 			return msg.WrapErr(err, err.Error())
 		}
-	} else if err = ensureFile(target, 0444); err != nil {
+	} else if err = ensureFile(target, 0444, 0700); err != nil {
 		return err
 	}
 
@@ -147,7 +150,7 @@ func (d MountDev) apply(params *Params) error {
 
 	for _, name := range []string{"null", "zero", "full", "random", "urandom", "tty"} {
 		targetPath := toSysroot(path.Join(v, name))
-		if err := ensureFile(targetPath, 0444); err != nil {
+		if err := ensureFile(targetPath, 0444, 0755); err != nil {
 			return err
 		}
 		if err := hostProc.bindMount(
@@ -198,7 +201,7 @@ func (d MountDev) apply(params *Params) error {
 			uintptr(unsafe.Pointer(&buf[0])),
 		); errno == 0 {
 			consolePath := toSysroot(path.Join(v, "console"))
-			if err := ensureFile(consolePath, 0444); err != nil {
+			if err := ensureFile(consolePath, 0444, 0755); err != nil {
 				return err
 			}
 			if err := hostProc.bindMount(
@@ -313,29 +316,29 @@ func (f *Ops) Link(target, linkName string) *Ops {
 func init() { gob.Register(new(Mkdir)) }
 
 // Mkdir creates a directory in the container filesystem.
-type Mkdir string
+type Mkdir struct {
+	Path string
+	Perm os.FileMode
+}
 
-func (m Mkdir) early(*Params) error { return nil }
-func (m Mkdir) apply(*Params) error {
-	v := string(m)
-
-	if !path.IsAbs(v) {
+func (m *Mkdir) early(*Params) error { return nil }
+func (m *Mkdir) apply(*Params) error {
+	if !path.IsAbs(m.Path) {
 		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", v))
+			fmt.Sprintf("path %q is not absolute", m.Path))
 	}
 
-	target := toSysroot(v)
-	if err := os.MkdirAll(target, 0755); err != nil {
+	if err := os.MkdirAll(toSysroot(m.Path), m.Perm); err != nil {
 		return msg.WrapErr(err, err.Error())
 	}
 	return nil
 }
 
-func (m Mkdir) Is(op Op) bool  { vm, ok := op.(Mkdir); return ok && m == vm }
-func (Mkdir) prefix() string   { return "creating" }
-func (m Mkdir) String() string { return fmt.Sprintf("directory %q", string(m)) }
-func (f *Ops) Mkdir(dest string) *Ops {
-	*f = append(*f, Mkdir(dest))
+func (m *Mkdir) Is(op Op) bool  { vm, ok := op.(*Mkdir); return ok && m == vm }
+func (*Mkdir) prefix() string   { return "creating" }
+func (m *Mkdir) String() string { return fmt.Sprintf("directory %q perm %s", m.Path, m.Perm) }
+func (f *Ops) Mkdir(dest string, perm os.FileMode) *Ops {
+	*f = append(*f, &Mkdir{dest, perm})
 	return f
 }
 
@@ -368,7 +371,7 @@ func (t *Tmpfile) apply(*Params) error {
 	}
 
 	target := toSysroot(t.Path)
-	if err := ensureFile(target, 0444); err != nil {
+	if err := ensureFile(target, 0444, 0755); err != nil {
 		return err
 	} else if err = hostProc.bindMount(
 		tmpPath,