Add container name to unique path keys

This is to allow multi-containers to be saved/restored
without conflicting "unique" IDs.

Updates #1956

PiperOrigin-RevId: 601231193

pkg/sentry/fsimpl/erofs/erofs.go

@@ -81,7 +81,7 @@ type filesystem struct {
 type InternalFilesystemOptions struct {
 	// If UniqueID is non-empty, it is an opaque string used to reassociate the
 	// filesystem with a new image FD during restoration from checkpoint.
-	UniqueID string
+	UniqueID vfs.RestoreID
 }
 
 // Name implements vfs.FilesystemType.Name.

pkg/sentry/fsimpl/erofs/save_restore.go

@@ -38,7 +38,7 @@ func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRest
 	if fdmapv == nil {
 		return fmt.Errorf("no image FD map available")
 	}
-	fdmap := fdmapv.(map[string]int)
+	fdmap := fdmapv.(map[vfs.RestoreID]int)
 	fd, ok := fdmap[fs.iopts.UniqueID]
 	if !ok {
 		return fmt.Errorf("no image FD available for filesystem with unique ID %q", fs.iopts.UniqueID)

pkg/sentry/fsimpl/gofer/gofer.go

@@ -363,7 +363,7 @@ const (
 type InternalFilesystemOptions struct {
 	// If UniqueID is non-empty, it is an opaque string used to reassociate the
 	// filesystem with a new server FD during restoration from checkpoint.
-	UniqueID string
+	UniqueID vfs.RestoreID
 
 	// If LeakConnection is true, do not close the connection to the server
 	// when the Filesystem is released. This is necessary for deployments in

pkg/sentry/fsimpl/gofer/save_restore.go

@@ -37,7 +37,7 @@ type savedDentryRW struct {
 
 // PrepareSave implements vfs.FilesystemImplSaveRestoreExtension.PrepareSave.
 func (fs *filesystem) PrepareSave(ctx context.Context) error {
-	if len(fs.iopts.UniqueID) == 0 {
+	if len(fs.iopts.UniqueID.Path) == 0 {
 		return fmt.Errorf("gofer.filesystem with no UniqueID cannot be saved")
 	}
 
@@ -176,10 +176,10 @@ func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRest
 	if fdmapv == nil {
 		return fmt.Errorf("no server FD map available")
 	}
-	fdmap := fdmapv.(map[string]int)
+	fdmap := fdmapv.(map[vfs.RestoreID]int)
 	fd, ok := fdmap[fs.iopts.UniqueID]
 	if !ok {
-		return fmt.Errorf("no server FD available for filesystem with unique ID %q", fs.iopts.UniqueID)
+		return fmt.Errorf("no server FD available for filesystem with unique ID %+v, map: %v", fs.iopts.UniqueID, fdmap)
 	}
 	fs.opts.fd = fd
 	fs.inoByKey = make(map[inoKey]uint64)

pkg/sentry/fsimpl/tmpfs/save_restore.go

@@ -48,7 +48,7 @@ func (fs *filesystem) PrepareSave(ctx context.Context) error {
 	if mfmapv == nil {
 		return fmt.Errorf("CtxFilesystemMemoryFileMap was not provided")
 	}
-	mfmap := mfmapv.(map[string]*pgalloc.MemoryFile)
+	mfmap := mfmapv.(map[vfs.RestoreID]*pgalloc.MemoryFile)
 	mfmap[fs.uniqueID] = fs.mf
 	return nil
 }
@@ -63,7 +63,7 @@ func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRest
 	if mfmapv == nil {
 		return fmt.Errorf("CtxFilesystemMemoryFileMap was not provided")
 	}
-	mfmap := mfmapv.(map[string]*pgalloc.MemoryFile)
+	mfmap := mfmapv.(map[vfs.RestoreID]*pgalloc.MemoryFile)
 	mf, ok := mfmap[fs.uniqueID]
 	if !ok {
 		return fmt.Errorf("memory file for %q not found in CtxFilesystemMemoryFileMap", fs.uniqueID)

pkg/sentry/fsimpl/tmpfs/tmpfs.go

@@ -72,7 +72,7 @@ type filesystem struct {
 
 	// uniqueID is an opaque string used to reassociate the filesystem with its
 	// private MemoryFile during checkpoint and restore.
-	uniqueID string
+	uniqueID vfs.RestoreID
 
 	// mfp is used to provide mf, when privateMF == false. This is required to
 	// re-provide mf on restore. mfp is immutable.
@@ -159,7 +159,7 @@ type FilesystemOpts struct {
 
 	// If UniqueID is non-empty, it is an opaque string used to reassociate the
 	// filesystem with its private MemoryFile during checkpoint and restore.
-	UniqueID string
+	UniqueID vfs.RestoreID
 }
 
 // Default size limit mount option. It is immutable after initialization.
@@ -192,7 +192,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 	}
 	mf := mfp.MemoryFile()
 	privateMF := false
-	uniqueID := ""
+	var uniqueID vfs.RestoreID
 	rootFileType := uint16(linux.S_IFDIR)
 	disableDefaultSizeLimit := false
 	newFSType := vfs.FilesystemType(&fstype)
@@ -225,7 +225,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 			allowXattrPrefix[xattr] = struct{}{}
 		}
 	}
-	if privateMF && uniqueID == "" {
+	if privateMF && len(uniqueID.Path) == 0 {
 		ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: privateMF requires uniqueID to be set")
 		return nil, nil, linuxerr.EINVAL
 	}

pkg/sentry/kernel/kernel.go

@@ -505,10 +505,10 @@ func (k *Kernel) Init(args InitKernelArgs) error {
 
 // +stateify savable
 type privateMemoryFileMetadata struct {
-	owners []string
+	owners []vfs.RestoreID
 }
 
-func savePrivateMFs(ctx context.Context, w wire.Writer, mfsToSave map[string]*pgalloc.MemoryFile) error {
+func savePrivateMFs(ctx context.Context, w wire.Writer, mfsToSave map[vfs.RestoreID]*pgalloc.MemoryFile) error {
 	var meta privateMemoryFileMetadata
 	// Generate the order in which private memory files are saved.
 	for fsID := range mfsToSave {
@@ -533,9 +533,9 @@ func loadPrivateMFs(ctx context.Context, r wire.Reader) error {
 	if _, err := state.Load(ctx, r, &meta); err != nil {
 		return err
 	}
-	var mfmap map[string]*pgalloc.MemoryFile
+	var mfmap map[vfs.RestoreID]*pgalloc.MemoryFile
 	if mfmapv := ctx.Value(vfs.CtxFilesystemMemoryFileMap); mfmapv != nil {
-		mfmap = mfmapv.(map[string]*pgalloc.MemoryFile)
+		mfmap = mfmapv.(map[vfs.RestoreID]*pgalloc.MemoryFile)
 	}
 	// Ensure that it is consistent with CtxFilesystemMemoryFileMap.
 	if len(mfmap) != len(meta.owners) {
@@ -578,7 +578,7 @@ func (k *Kernel) SaveTo(ctx context.Context, w wire.Writer) error {
 	}
 
 	// Capture all private memory files.
-	mfsToSave := make(map[string]*pgalloc.MemoryFile)
+	mfsToSave := make(map[vfs.RestoreID]*pgalloc.MemoryFile)
 	vfsCtx := context.WithValue(ctx, vfs.CtxFilesystemMemoryFileMap, mfsToSave)
 	// Prepare filesystems for saving. This must be done after
 	// invalidateUnsavableMappings(), since dropping memory mappings may

pkg/sentry/vfs/save_restore.go

@@ -15,6 +15,7 @@
 package vfs
 
 import (
+	"fmt"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/context"
@@ -133,3 +134,18 @@ func (epi *epollInterest) afterLoad() {
 	// EpollInstance.ReadEvents() rechecks their readiness.
 	epi.waiter.NotifyEvent(waiter.EventMaskFromLinux(epi.mask))
 }
+
+// RestoreID is a unique ID that is used to identify resources between save/restore sessions.
+// Example of resources are host files, gofer connection for mount points, etc.
+//
+// +stateify savable
+type RestoreID struct {
+	// ContainerName is the name of the container that the resource belongs to.
+	ContainerName string
+	// Path is the path of the resource.
+	Path string
+}
+
+func (f RestoreID) String() string {
+	return fmt.Sprintf("%s:%s", f.ContainerName, f.Path)
+}

runsc/boot/loader.go

@@ -95,6 +95,8 @@ import (
 type containerInfo struct {
 	cid string
 
+	containerName string
+
 	conf *config.Config
 
 	// spec is the base configuration for the root container.
@@ -328,6 +330,7 @@ func New(args Args) (*Loader, error) {
 
 	info := containerInfo{
 		cid:                 args.ID,
+		containerName:       specutils.ContainerName(args.Spec),
 		conf:                args.Conf,
 		spec:                args.Spec,
 		goferMountConfs:     args.GoferMountConfs,
@@ -899,6 +902,7 @@ func (l *Loader) startSubcontainer(spec *specs.Spec, conf *config.Config, cid st
 
 	info := &containerInfo{
 		cid:                 cid,
+		containerName:       specutils.ContainerName(spec),
 		conf:                conf,
 		spec:                spec,
 		goferFDs:            goferFDs,
@@ -973,7 +977,7 @@ func (l *Loader) startSubcontainer(spec *specs.Spec, conf *config.Config, cid st
 func (l *Loader) createContainerProcess(info *containerInfo) (*kernel.ThreadGroup, *host.TTYFileDescription, error) {
 	// Create the FD map, which will set stdin, stdout, and stderr.
 	ctx := info.procArgs.NewContext(l.k)
-	fdTable, ttyFile, err := createFDTable(ctx, info.spec.Process.Terminal, info.stdioFDs, info.passFDs, info.spec.Process.User)
+	fdTable, ttyFile, err := createFDTable(ctx, info.spec.Process.Terminal, info.stdioFDs, info.passFDs, info.spec.Process.User, info.containerName)
 	if err != nil {
 		return nil, nil, fmt.Errorf("importing fds: %w", err)
 	}
@@ -1572,7 +1576,7 @@ func (l *Loader) ttyFromIDLocked(key execID) (*host.TTYFileDescription, error) {
 	return ep.tty, nil
 }
 
-func createFDTable(ctx context.Context, console bool, stdioFDs []*fd.FD, passFDs []fdMapping, user specs.User) (*kernel.FDTable, *host.TTYFileDescription, error) {
+func createFDTable(ctx context.Context, console bool, stdioFDs []*fd.FD, passFDs []fdMapping, user specs.User, containerName string) (*kernel.FDTable, *host.TTYFileDescription, error) {
 	if len(stdioFDs) != 3 {
 		return nil, nil, fmt.Errorf("stdioFDs should contain exactly 3 FDs (stdin, stdout, and stderr), but %d FDs received", len(stdioFDs))
 	}

runsc/boot/vfs.go

@@ -402,7 +402,8 @@ type containerMounter struct {
 	containerID string
 
 	// sandboxID is the ID for the whole sandbox.
-	sandboxID string
+	sandboxID     string
+	containerName string
 
 	// cgroupMounts is a map of cgroup mounts that can be reused across
 	// containers. Key is the cgroup controller name string.
@@ -434,6 +435,7 @@ func newContainerMounter(info *containerInfo, k *kernel.Kernel, hints *PodMountH
 		productName:       productName,
 		containerID:       info.procArgs.ContainerID,
 		sandboxID:         sandboxID,
+		containerName:     info.containerName,
 		cgroupMounts:      cgroupMounts,
 	}
 }
@@ -519,7 +521,10 @@ func (c *containerMounter) createMountNamespace(ctx context.Context, conf *confi
 				InternalMount: true,
 				Data:          strings.Join(data, ","),
 				InternalData: gofer.InternalFilesystemOptions{
-					UniqueID: "/",
+					UniqueID: vfs.RestoreID{
+						ContainerName: c.containerName,
+						Path:          "/",
+					},
 				},
 			},
 		}
@@ -532,7 +537,10 @@ func (c *containerMounter) createMountNamespace(ctx context.Context, conf *confi
 				InternalMount: true,
 				Data:          fmt.Sprintf("ifd=%d", ioFD),
 				InternalData: erofs.InternalFilesystemOptions{
-					UniqueID: "/",
+					UniqueID: vfs.RestoreID{
+						ContainerName: c.containerName,
+						Path:          "/",
+					},
 				},
 			},
 		}
@@ -645,7 +653,7 @@ func (c *containerMounter) configureOverlay(ctx context.Context, conf *config.Co
 			return nil, nil, fmt.Errorf("failed to create memory file for overlay: %v", err)
 		}
 		tmpfsOpts.MemoryFile = mf
-		tmpfsOpts.UniqueID = dst
+		tmpfsOpts.UniqueID = vfs.RestoreID{ContainerName: c.containerName, Path: dst}
 	}
 	upperOpts.GetFilesystemOptions.InternalData = tmpfsOpts
 	upper, err := c.k.VFS().MountDisconnected(ctx, creds, "" /* source */, tmpfs.Name, &upperOpts)
@@ -829,7 +837,7 @@ func (c *containerMounter) prepareMounts() ([]mountInfo, error) {
 }
 
 func (c *containerMounter) mountSubmount(ctx context.Context, spec *specs.Spec, conf *config.Config, mns *vfs.MountNamespace, creds *auth.Credentials, submount *mountInfo) (*vfs.Mount, error) {
-	fsName, opts, err := getMountNameAndOptions(spec, conf, submount, c.productName)
+	fsName, opts, err := getMountNameAndOptions(spec, conf, submount, c.productName, c.containerName)
 	if err != nil {
 		return nil, fmt.Errorf("mountOptions failed: %w", err)
 	}
@@ -870,7 +878,7 @@ func (c *containerMounter) mountSubmount(ctx context.Context, spec *specs.Spec,
 
 // getMountNameAndOptions retrieves the fsName, opts, and useOverlay values
 // used for mounts.
-func getMountNameAndOptions(spec *specs.Spec, conf *config.Config, m *mountInfo, productName string) (string, *vfs.MountOptions, error) {
+func getMountNameAndOptions(spec *specs.Spec, conf *config.Config, m *mountInfo, productName, containerName string) (string, *vfs.MountOptions, error) {
 	fsName := m.mount.Type
 	var (
 		mopts        = m.mount.Options
@@ -906,7 +914,7 @@ func getMountNameAndOptions(spec *specs.Spec, conf *config.Config, m *mountInfo,
 			}
 			internalData = tmpfs.FilesystemOpts{
 				MemoryFile: mf,
-				UniqueID:   m.mount.Destination,
+				UniqueID:   vfs.RestoreID{ContainerName: containerName, Path: m.mount.Destination},
 				// If a mount is being overlaid with tmpfs, it should not be limited by
 				// the default tmpfs size limit.
 				DisableDefaultSizeLimit: true,
@@ -926,7 +934,10 @@ func getMountNameAndOptions(spec *specs.Spec, conf *config.Config, m *mountInfo,
 		}
 		data = append(data, goferMountData(m.goferFD.Release(), getMountAccessType(conf, m.hint), conf)...)
 		internalData = gofer.InternalFilesystemOptions{
-			UniqueID: m.mount.Destination,
+			UniqueID: vfs.RestoreID{
+				ContainerName: containerName,
+				Path:          m.mount.Destination,
+			},
 		}
 
 	case cgroupfs.Name:
@@ -1204,7 +1215,7 @@ func (c *containerMounter) mountSharedMaster(ctx context.Context, spec *specs.Sp
 	// Mount the master using the options from the hint (mount annotations).
 	origOpts := mntInfo.mount.Options
 	mntInfo.mount.Options = mntInfo.hint.Mount.Options
-	fsName, opts, err := getMountNameAndOptions(spec, conf, mntInfo, c.productName)
+	fsName, opts, err := getMountNameAndOptions(spec, conf, mntInfo, c.productName, c.containerName)
 	mntInfo.mount.Options = origOpts
 	if err != nil {
 		return nil, err
@@ -1271,15 +1282,18 @@ func (c *containerMounter) makeMountPoint(ctx context.Context, creds *auth.Crede
 func (c *containerMounter) configureRestore(ctx context.Context) (context.Context, error) {
 	// Compare createMountNamespace(); rootfs always consumes a gofer FD and a
 	// filestore FD is consumed if the rootfs GoferMountConf indicates so.
-	fdmap := make(map[string]int)
-	fdmap["/"] = c.goferFDs.remove()
-	mfmap := make(map[string]*pgalloc.MemoryFile)
+	fdmap := make(map[vfs.RestoreID]int)
+
+	rootKey := vfs.RestoreID{ContainerName: c.containerName, Path: "/"}
+	fdmap[rootKey] = c.goferFDs.remove()
+
+	mfmap := make(map[vfs.RestoreID]*pgalloc.MemoryFile)
 	if rootfsConf := c.goferMountConfs[0]; rootfsConf.IsFilestorePresent() {
 		mf, err := createPrivateMemoryFile(c.goferFilestoreFDs.removeAsFD().ReleaseToFile("overlay-filestore"))
 		if err != nil {
 			return ctx, fmt.Errorf("failed to create private memory file for mount rootfs: %w", err)
 		}
-		mfmap["/"] = mf
+		mfmap[rootKey] = mf
 	}
 	// prepareMounts() consumes the remaining FDs for submounts.
 	mounts, err := c.prepareMounts()
@@ -1289,14 +1303,16 @@ func (c *containerMounter) configureRestore(ctx context.Context) (context.Contex
 	for i := range mounts {
 		submount := &mounts[i]
 		if submount.goferFD != nil {
-			fdmap[submount.mount.Destination] = submount.goferFD.Release()
+			key := vfs.RestoreID{ContainerName: c.containerName, Path: submount.mount.Destination}
+			fdmap[key] = submount.goferFD.Release()
 		}
 		if submount.filestoreFD != nil {
 			mf, err := createPrivateMemoryFile(submount.filestoreFD.ReleaseToFile("overlay-filestore"))
 			if err != nil {
 				return ctx, fmt.Errorf("failed to create private memory file for mount %q: %w", submount.mount.Destination, err)
 			}
-			mfmap[submount.mount.Destination] = mf
+			key := vfs.RestoreID{ContainerName: c.containerName, Path: submount.mount.Destination}
+			mfmap[key] = mf
 		}
 	}
 	return context.WithValue(context.WithValue(ctx, vfs.CtxRestoreFilesystemFDMap, fdmap), vfs.CtxFilesystemMemoryFileMap, mfmap), nil

runsc/specutils/specutils.go

@@ -241,15 +241,7 @@ func fixSpec(spec *specs.Spec, bundleDir string, conf *config.Config) error {
 		}
 	}
 
-	// Check annotation to see if container name is available.
-	var containerName string
-	for key, val := range spec.Annotations {
-		if key == annotationContainerName {
-			containerName = val
-			log.Debugf("Container name: %q", containerName)
-			break
-		}
-	}
+	containerName := ContainerName(spec)
 	for annotation, val := range spec.Annotations {
 		if strings.HasPrefix(annotation, annotationFlagPrefix) {
 			// Override flags using annotation to allow customization per sandbox
@@ -758,3 +750,9 @@ func ResolveEnvs(envs ...[]string) ([]string, error) {
 func FaqErrorMsg(anchor, msg string) string {
 	return fmt.Sprintf("%s; see https://gvisor.dev/faq#%s for more details", msg, anchor)
 }
+
+// ContainerName looks for an annotation in the spec with the container name. Returns empty string
+// if no annotation is found.
+func ContainerName(spec *specs.Spec) string {
+	return spec.Annotations[annotationContainerName]
+}