Allow filesystem.Mount to take an optional interface argument.

PiperOrigin-RevId: 238360231
Change-Id: I5eaf8d26f8892f77d71c7fbd6c5225ef471cedf1

16 files changed, 42 insertions, 39 deletions

diff --git a/pkg/sentry/fs/copy_up_test.go b/pkg/sentry/fs/copy_up_test.go
index 2b2f4bb8f..98a0b7638 100644
--- a/pkg/sentry/fs/copy_up_test.go
+++ b/pkg/sentry/fs/copy_up_test.go
@@ -98,7 +98,7 @@ func makeOverlayTestFiles(t *testing.T) []*overlayTestFile {
 
 	// Create a lower tmpfs mount.
 	fsys, _ := fs.FindFilesystem("tmpfs")
-	lower, err := fsys.Mount(contexttest.Context(t), "", fs.MountSourceFlags{}, "")
+	lower, err := fsys.Mount(contexttest.Context(t), "", fs.MountSourceFlags{}, "", nil)
 	if err != nil {
 		t.Fatalf("failed to mount tmpfs: %v", err)
 	}
@@ -147,7 +147,7 @@ func makeOverlayTestFiles(t *testing.T) []*overlayTestFile {
 	}
 
 	// Create an empty upper tmpfs mount which we will copy up into.
-	upper, err := fsys.Mount(ctx, "", fs.MountSourceFlags{}, "")
+	upper, err := fsys.Mount(ctx, "", fs.MountSourceFlags{}, "", nil)
 	if err != nil {
 		t.Fatalf("failed to mount tmpfs: %v", err)
 	}
diff --git a/pkg/sentry/fs/dev/fs.go b/pkg/sentry/fs/dev/fs.go
index abfe689f0..cf4e7d00f 100644
--- a/pkg/sentry/fs/dev/fs.go
+++ b/pkg/sentry/fs/dev/fs.go
@@ -66,7 +66,7 @@ func (*filesystem) Flags() fs.FilesystemFlags {
 }
 
 // Mount returns a devtmpfs root that can be positioned in the vfs.
-func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// device is always ignored.
 	// devtmpfs backed by ramfs ignores bad options. See fs/ramfs/inode.c:ramfs_parse_options.
 	//  -> we should consider parsing the mode and backing devtmpfs by this.
diff --git a/pkg/sentry/fs/filesystems.go b/pkg/sentry/fs/filesystems.go
index ba8be85e4..aa664b973 100644
--- a/pkg/sentry/fs/filesystems.go
+++ b/pkg/sentry/fs/filesystems.go
@@ -50,7 +50,7 @@ type Filesystem interface {
 	// data options.
 	//
 	// Mount may return arbitrary errors. They do not need syserr translations.
-	Mount(ctx context.Context, device string, flags MountSourceFlags, data string) (*Inode, error)
+	Mount(ctx context.Context, device string, flags MountSourceFlags, data string, dataObj interface{}) (*Inode, error)
 
 	// AllowUserMount determines whether mount(2) is allowed to mount a
 	// file system of this type.
diff --git a/pkg/sentry/fs/gofer/fs.go b/pkg/sentry/fs/gofer/fs.go
index 2dc000c6f..adff0abac 100644
--- a/pkg/sentry/fs/gofer/fs.go
+++ b/pkg/sentry/fs/gofer/fs.go
@@ -120,7 +120,7 @@ func (*filesystem) Flags() fs.FilesystemFlags {
 }
 
 // Mount returns an attached 9p client that can be positioned in the vfs.
-func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// Parse and validate the mount options.
 	o, err := options(data)
 	if err != nil {
diff --git a/pkg/sentry/fs/gofer/session_state.go b/pkg/sentry/fs/gofer/session_state.go
index d9fd7a221..0ad5d63b5 100644
--- a/pkg/sentry/fs/gofer/session_state.go
+++ b/pkg/sentry/fs/gofer/session_state.go
@@ -57,7 +57,7 @@ func (s *session) afterLoad() {
 	}
 
 	// Validate the mount flags and options.
-	opts, err := options(args.Data)
+	opts, err := options(args.DataString)
 	if err != nil {
 		panic("failed to parse mount options: " + err.Error())
 	}
diff --git a/pkg/sentry/fs/host/fs.go b/pkg/sentry/fs/host/fs.go
index d2ba38449..800649211 100644
--- a/pkg/sentry/fs/host/fs.go
+++ b/pkg/sentry/fs/host/fs.go
@@ -82,7 +82,7 @@ func (*Filesystem) Flags() fs.FilesystemFlags {
 
 // Mount returns an fs.Inode exposing the host file system.  It is intended to be locked
 // down in PreExec below.
-func (f *Filesystem) Mount(ctx context.Context, _ string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *Filesystem) Mount(ctx context.Context, _ string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// Parse generic comma-separated key=value options.
 	options := fs.GenericMountSourceOptions(data)
 
diff --git a/pkg/sentry/fs/host/fs_test.go b/pkg/sentry/fs/host/fs_test.go
index 44db61ecd..c83b29a16 100644
--- a/pkg/sentry/fs/host/fs_test.go
+++ b/pkg/sentry/fs/host/fs_test.go
@@ -321,7 +321,7 @@ func TestRootPath(t *testing.T) {
 	hostFS := &Filesystem{}
 	ctx := contexttest.Context(t)
 	data := fmt.Sprintf("%s=%s,%s=%s", rootPathKey, rootPath, whitelistKey, whitelisted.Name())
-	inode, err := hostFS.Mount(ctx, "", fs.MountSourceFlags{}, data)
+	inode, err := hostFS.Mount(ctx, "", fs.MountSourceFlags{}, data, nil)
 	if err != nil {
 		t.Fatalf("Mount failed: %v", err)
 	}
diff --git a/pkg/sentry/fs/mount_overlay.go b/pkg/sentry/fs/mount_overlay.go
index fb91635bc..4c89673b5 100644
--- a/pkg/sentry/fs/mount_overlay.go
+++ b/pkg/sentry/fs/mount_overlay.go
@@ -122,6 +122,6 @@ func (*overlayFilesystem) AllowUserList() bool {
 }
 
 // Mount implements Filesystem.Mount.
-func (ofs *overlayFilesystem) Mount(ctx context.Context, device string, flags MountSourceFlags, data string) (*Inode, error) {
+func (ofs *overlayFilesystem) Mount(ctx context.Context, device string, flags MountSourceFlags, data string, _ interface{}) (*Inode, error) {
 	panic("overlayFilesystem.Mount should not be called!")
 }
diff --git a/pkg/sentry/fs/proc/fs.go b/pkg/sentry/fs/proc/fs.go
index 63f737ff4..666a2d054 100644
--- a/pkg/sentry/fs/proc/fs.go
+++ b/pkg/sentry/fs/proc/fs.go
@@ -57,7 +57,7 @@ func (*filesystem) Flags() fs.FilesystemFlags {
 }
 
 // Mount returns the root of a procfs that can be positioned in the vfs.
-func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// device is always ignored.
 
 	// Parse generic comma-separated key=value options, this file system expects them.
diff --git a/pkg/sentry/fs/restore.go b/pkg/sentry/fs/restore.go
index da2df7e1d..a6645b41e 100644
--- a/pkg/sentry/fs/restore.go
+++ b/pkg/sentry/fs/restore.go
@@ -41,8 +41,11 @@ type MountArgs struct {
 	// Flags corresponds to the flags argument of Mount.
 	Flags MountSourceFlags
 
-	// Data corresponds to the data argument of Mount.
-	Data string
+	// DataString corresponds to the data argument of Mount.
+	DataString string
+
+	// DataObj corresponds to the data interface argument of Mount.
+	DataObj interface{}
 }
 
 // restoreEnv holds the fs package global RestoreEnvironment.
diff --git a/pkg/sentry/fs/sys/fs.go b/pkg/sentry/fs/sys/fs.go
index 301fef038..44ae43754 100644
--- a/pkg/sentry/fs/sys/fs.go
+++ b/pkg/sentry/fs/sys/fs.go
@@ -57,7 +57,7 @@ func (*filesystem) Flags() fs.FilesystemFlags {
 }
 
 // Mount returns a sysfs root which can be positioned in the vfs.
-func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// device is always ignored.
 	// sysfs ignores data, see fs/sysfs/mount.c:sysfs_mount.
 
diff --git a/pkg/sentry/fs/tmpfs/fs.go b/pkg/sentry/fs/tmpfs/fs.go
index d495430e9..d0c93028f 100644
--- a/pkg/sentry/fs/tmpfs/fs.go
+++ b/pkg/sentry/fs/tmpfs/fs.go
@@ -82,7 +82,7 @@ func (*Filesystem) Flags() fs.FilesystemFlags {
 }
 
 // Mount returns a tmpfs root that can be positioned in the vfs.
-func (f *Filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *Filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// device is always ignored.
 
 	// Parse generic comma-separated key=value options, this file system expects them.
diff --git a/pkg/sentry/fs/tty/fs.go b/pkg/sentry/fs/tty/fs.go
index 0c412eb21..43e0e2a04 100644
--- a/pkg/sentry/fs/tty/fs.go
+++ b/pkg/sentry/fs/tty/fs.go
@@ -59,7 +59,7 @@ func (*filesystem) Flags() fs.FilesystemFlags {
 }
 
 // MountSource returns a devpts root that can be positioned in the vfs.
-func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string) (*fs.Inode, error) {
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
 	// device is always ignored.
 
 	// No options are supported.
diff --git a/pkg/sentry/syscalls/linux/sys_mount.go b/pkg/sentry/syscalls/linux/sys_mount.go
index bf0df7302..6b8d75d24 100644
--- a/pkg/sentry/syscalls/linux/sys_mount.go
+++ b/pkg/sentry/syscalls/linux/sys_mount.go
@@ -101,7 +101,7 @@ func Mount(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 		superFlags.ReadOnly = true
 	}
 
-	rootInode, err := rsys.Mount(t, sourcePath, superFlags, data)
+	rootInode, err := rsys.Mount(t, sourcePath, superFlags, data, nil)
 	if err != nil {
 		return 0, nil, syserror.EINVAL
 	}
diff --git a/runsc/boot/fs.go b/runsc/boot/fs.go
index ada292c9e..25e23c09b 100644
--- a/runsc/boot/fs.go
+++ b/runsc/boot/fs.go
@@ -181,7 +181,7 @@ func createRootMount(ctx context.Context, spec *specs.Spec, conf *Config, fds *f
 	log.Infof("Mounting root over 9P, ioFD: %d", fd)
 	p9FS := mustFindFilesystem("9p")
 	opts := p9MountOptions(fd, conf.FileAccess)
-	rootInode, err = p9FS.Mount(ctx, rootDevice, mf, strings.Join(opts, ","))
+	rootInode, err = p9FS.Mount(ctx, rootDevice, mf, strings.Join(opts, ","), nil)
 	if err != nil {
 		return nil, fmt.Errorf("creating root mount point: %v", err)
 	}
@@ -220,7 +220,7 @@ func addOverlay(ctx context.Context, conf *Config, lower *fs.Inode, name string,
 	}
 
 	// Create overlay on top of mount dir.
-	upper, err := tmpFS.Mount(ctx, name+"-upper", lowerFlags, "")
+	upper, err := tmpFS.Mount(ctx, name+"-upper", lowerFlags, "", nil)
 	if err != nil {
 		return nil, fmt.Errorf("creating tmpfs overlay: %v", err)
 	}
@@ -309,7 +309,7 @@ func mountSubmount(ctx context.Context, conf *Config, mns *fs.MountNamespace, ro
 		mf.ReadOnly = true
 	}
 
-	inode, err := filesystem.Mount(ctx, mountDevice(m), mf, strings.Join(opts, ","))
+	inode, err := filesystem.Mount(ctx, mountDevice(m), mf, strings.Join(opts, ","), nil)
 	if err != nil {
 		return fmt.Errorf("creating mount with source %q: %v", m.Source, err)
 	}
@@ -415,9 +415,9 @@ func addRestoreMount(conf *Config, renv *fs.RestoreEnvironment, m specs.Mount, f
 	}
 
 	newMount := fs.MountArgs{
-		Dev:   mountDevice(m),
-		Flags: mountFlags(m.Options),
-		Data:  strings.Join(opts, ","),
+		Dev:        mountDevice(m),
+		Flags:      mountFlags(m.Options),
+		DataString: strings.Join(opts, ","),
 	}
 	renv.MountSources[fsName] = append(renv.MountSources[fsName], newMount)
 	log.Infof("Added mount at %q: %+v", fsName, newMount)
@@ -441,9 +441,9 @@ func createRestoreEnvironment(spec *specs.Spec, conf *Config, fds *fdDispenser)
 	}
 
 	rootMount := fs.MountArgs{
-		Dev:   rootDevice,
-		Flags: mf,
-		Data:  strings.Join(opts, ","),
+		Dev:        rootDevice,
+		Flags:      mf,
+		DataString: strings.Join(opts, ","),
 	}
 	renv.MountSources[rootFsName] = append(renv.MountSources[rootFsName], rootMount)
 
diff --git a/runsc/boot/loader_test.go b/runsc/boot/loader_test.go
index 4fcc0faea..01578cfc5 100644
--- a/runsc/boot/loader_test.go
+++ b/runsc/boot/loader_test.go
@@ -456,9 +456,9 @@ func TestRestoreEnvironment(t *testing.T) {
 				MountSources: map[string][]fs.MountArgs{
 					"9p": {
 						{
-							Dev:   "9pfs-/",
-							Flags: fs.MountSourceFlags{ReadOnly: true},
-							Data:  "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
+							Dev:        "9pfs-/",
+							Flags:      fs.MountSourceFlags{ReadOnly: true},
+							DataString: "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
 						},
 					},
 					"tmpfs": {
@@ -510,13 +510,13 @@ func TestRestoreEnvironment(t *testing.T) {
 				MountSources: map[string][]fs.MountArgs{
 					"9p": {
 						{
-							Dev:   "9pfs-/",
-							Flags: fs.MountSourceFlags{ReadOnly: true},
-							Data:  "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
+							Dev:        "9pfs-/",
+							Flags:      fs.MountSourceFlags{ReadOnly: true},
+							DataString: "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
 						},
 						{
-							Dev:  "9pfs-/dev/fd-foo",
-							Data: "trans=fd,rfdno=1,wfdno=1,privateunixsocket=true,cache=remote_revalidating",
+							Dev:        "9pfs-/dev/fd-foo",
+							DataString: "trans=fd,rfdno=1,wfdno=1,privateunixsocket=true,cache=remote_revalidating",
 						},
 					},
 					"tmpfs": {
@@ -568,16 +568,16 @@ func TestRestoreEnvironment(t *testing.T) {
 				MountSources: map[string][]fs.MountArgs{
 					"9p": {
 						{
-							Dev:   "9pfs-/",
-							Flags: fs.MountSourceFlags{ReadOnly: true},
-							Data:  "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
+							Dev:        "9pfs-/",
+							Flags:      fs.MountSourceFlags{ReadOnly: true},
+							DataString: "trans=fd,rfdno=0,wfdno=0,privateunixsocket=true,cache=remote_revalidating",
 						},
 					},
 					"tmpfs": {
 						{
-							Dev:   "none",
-							Flags: fs.MountSourceFlags{NoAtime: true},
-							Data:  "uid=1022",
+							Dev:        "none",
+							Flags:      fs.MountSourceFlags{NoAtime: true},
+							DataString: "uid=1022",
 						},
 						{
 							Dev: "none",