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-rw-r--r--pkg/sentry/fsimpl/overlay/filesystem.go8
-rw-r--r--pkg/sentry/fsimpl/overlay/overlay.go177
-rw-r--r--pkg/sentry/fsimpl/overlay/overlay_state_autogen.go27
3 files changed, 132 insertions, 80 deletions
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index 78a01bbb7..10161a08d 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -302,8 +302,14 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
child.devMinor = fs.dirDevMinor
child.ino = fs.newDirIno()
} else if !child.upperVD.Ok() {
+ childDevMinor, err := fs.getLowerDevMinor(child.devMajor, child.devMinor)
+ if err != nil {
+ ctx.Infof("overlay.filesystem.lookupLocked: failed to map lower layer device number (%d, %d) to an overlay-specific device number: %v", child.devMajor, child.devMinor, err)
+ child.destroyLocked(ctx)
+ return nil, err
+ }
child.devMajor = linux.UNNAMED_MAJOR
- child.devMinor = fs.lowerDevMinors[child.lowerVDs[0].Mount().Filesystem()]
+ child.devMinor = childDevMinor
}
parent.IncRef()
diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go
index 6fe97c57b..c812f0a70 100644
--- a/pkg/sentry/fsimpl/overlay/overlay.go
+++ b/pkg/sentry/fsimpl/overlay/overlay.go
@@ -22,6 +22,7 @@
// filesystem.renameMu
// dentry.dirMu
// dentry.copyMu
+// filesystem.devMu
// *** "memmap.Mappable locks" below this point
// dentry.mapsMu
// *** "memmap.Mappable locks taken by Translate" below this point
@@ -101,10 +102,15 @@ type filesystem struct {
// is immutable.
dirDevMinor uint32
- // lowerDevMinors maps lower layer filesystems to device minor numbers
- // assigned to non-directory files originating from that filesystem.
- // lowerDevMinors is immutable.
- lowerDevMinors map[*vfs.Filesystem]uint32
+ // lowerDevMinors maps device numbers from lower layer filesystems to
+ // device minor numbers assigned to non-directory files originating from
+ // that filesystem. (This remapping is necessary for lower layers because a
+ // file on a lower layer, and that same file on an overlay, are
+ // distinguishable because they will diverge after copy-up; this isn't true
+ // for non-directory files already on the upper layer.) lowerDevMinors is
+ // protected by devMu.
+ devMu sync.Mutex `state:"nosave"`
+ lowerDevMinors map[layerDevNumber]uint32
// renameMu synchronizes renaming with non-renaming operations in order to
// ensure consistent lock ordering between dentry.dirMu in different
@@ -116,78 +122,69 @@ type filesystem struct {
lastDirIno uint64
}
+// +stateify savable
+type layerDevNumber struct {
+ major uint32
+ minor uint32
+}
+
// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
mopts := vfs.GenericParseMountOptions(opts.Data)
fsoptsRaw := opts.InternalData
- fsopts, haveFSOpts := fsoptsRaw.(FilesystemOptions)
- if fsoptsRaw != nil && !haveFSOpts {
+ fsopts, ok := fsoptsRaw.(FilesystemOptions)
+ if fsoptsRaw != nil && !ok {
ctx.Infof("overlay.FilesystemType.GetFilesystem: GetFilesystemOptions.InternalData has type %T, wanted overlay.FilesystemOptions or nil", fsoptsRaw)
return nil, nil, syserror.EINVAL
}
- if haveFSOpts {
- if len(fsopts.LowerRoots) == 0 {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: LowerRoots must be non-empty")
+ vfsroot := vfs.RootFromContext(ctx)
+ if vfsroot.Ok() {
+ defer vfsroot.DecRef(ctx)
+ }
+
+ if upperPathname, ok := mopts["upperdir"]; ok {
+ if fsopts.UpperRoot.Ok() {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: both upperdir and FilesystemOptions.UpperRoot are specified")
return nil, nil, syserror.EINVAL
}
- if len(fsopts.LowerRoots) < 2 && !fsopts.UpperRoot.Ok() {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: at least two LowerRoots are required when UpperRoot is unspecified")
+ delete(mopts, "upperdir")
+ // Linux overlayfs also requires a workdir when upperdir is
+ // specified; we don't, so silently ignore this option.
+ delete(mopts, "workdir")
+ upperPath := fspath.Parse(upperPathname)
+ if !upperPath.Absolute {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: upperdir %q must be absolute", upperPathname)
return nil, nil, syserror.EINVAL
}
- // We don't enforce a maximum number of lower layers when not
- // configured by applications; the sandbox owner can have an overlay
- // filesystem with any number of lower layers.
- } else {
- vfsroot := vfs.RootFromContext(ctx)
- defer vfsroot.DecRef(ctx)
- upperPathname, ok := mopts["upperdir"]
- if ok {
- delete(mopts, "upperdir")
- // Linux overlayfs also requires a workdir when upperdir is
- // specified; we don't, so silently ignore this option.
- delete(mopts, "workdir")
- upperPath := fspath.Parse(upperPathname)
- if !upperPath.Absolute {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: upperdir %q must be absolute", upperPathname)
- return nil, nil, syserror.EINVAL
- }
- upperRoot, err := vfsObj.GetDentryAt(ctx, creds, &vfs.PathOperation{
- Root: vfsroot,
- Start: vfsroot,
- Path: upperPath,
- FollowFinalSymlink: true,
- }, &vfs.GetDentryOptions{
- CheckSearchable: true,
- })
- if err != nil {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to resolve upperdir %q: %v", upperPathname, err)
- return nil, nil, err
- }
- defer upperRoot.DecRef(ctx)
- privateUpperRoot, err := clonePrivateMount(vfsObj, upperRoot, false /* forceReadOnly */)
- if err != nil {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to make private bind mount of upperdir %q: %v", upperPathname, err)
- return nil, nil, err
- }
- defer privateUpperRoot.DecRef(ctx)
- fsopts.UpperRoot = privateUpperRoot
+ upperRoot, err := vfsObj.GetDentryAt(ctx, creds, &vfs.PathOperation{
+ Root: vfsroot,
+ Start: vfsroot,
+ Path: upperPath,
+ FollowFinalSymlink: true,
+ }, &vfs.GetDentryOptions{
+ CheckSearchable: true,
+ })
+ if err != nil {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to resolve upperdir %q: %v", upperPathname, err)
+ return nil, nil, err
}
- lowerPathnamesStr, ok := mopts["lowerdir"]
- if !ok {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: missing required option lowerdir")
+ privateUpperRoot, err := clonePrivateMount(vfsObj, upperRoot, false /* forceReadOnly */)
+ upperRoot.DecRef(ctx)
+ if err != nil {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to make private bind mount of upperdir %q: %v", upperPathname, err)
+ return nil, nil, err
+ }
+ defer privateUpperRoot.DecRef(ctx)
+ fsopts.UpperRoot = privateUpperRoot
+ }
+
+ if lowerPathnamesStr, ok := mopts["lowerdir"]; ok {
+ if len(fsopts.LowerRoots) != 0 {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: both lowerdir and FilesystemOptions.LowerRoots are specified")
return nil, nil, syserror.EINVAL
}
delete(mopts, "lowerdir")
lowerPathnames := strings.Split(lowerPathnamesStr, ":")
- const maxLowerLayers = 500 // Linux: fs/overlay/super.c:OVL_MAX_STACK
- if len(lowerPathnames) < 2 && !fsopts.UpperRoot.Ok() {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: at least two lowerdirs are required when upperdir is unspecified")
- return nil, nil, syserror.EINVAL
- }
- if len(lowerPathnames) > maxLowerLayers {
- ctx.Infof("overlay.FilesystemType.GetFilesystem: %d lowerdirs specified, maximum %d", len(lowerPathnames), maxLowerLayers)
- return nil, nil, syserror.EINVAL
- }
for _, lowerPathname := range lowerPathnames {
lowerPath := fspath.Parse(lowerPathname)
if !lowerPath.Absolute {
@@ -206,8 +203,8 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to resolve lowerdir %q: %v", lowerPathname, err)
return nil, nil, err
}
- defer lowerRoot.DecRef(ctx)
privateLowerRoot, err := clonePrivateMount(vfsObj, lowerRoot, true /* forceReadOnly */)
+ lowerRoot.DecRef(ctx)
if err != nil {
ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to make private bind mount of lowerdir %q: %v", lowerPathname, err)
return nil, nil, err
@@ -216,31 +213,31 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
fsopts.LowerRoots = append(fsopts.LowerRoots, privateLowerRoot)
}
}
+
if len(mopts) != 0 {
ctx.Infof("overlay.FilesystemType.GetFilesystem: unused options: %v", mopts)
return nil, nil, syserror.EINVAL
}
- // Allocate device numbers.
+ if len(fsopts.LowerRoots) == 0 {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: at least one lower layer is required")
+ return nil, nil, syserror.EINVAL
+ }
+ if len(fsopts.LowerRoots) < 2 && !fsopts.UpperRoot.Ok() {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: at least two lower layers are required when no upper layer is present")
+ return nil, nil, syserror.EINVAL
+ }
+ const maxLowerLayers = 500 // Linux: fs/overlay/super.c:OVL_MAX_STACK
+ if len(fsopts.LowerRoots) > maxLowerLayers {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: %d lower layers specified, maximum %d", len(fsopts.LowerRoots), maxLowerLayers)
+ return nil, nil, syserror.EINVAL
+ }
+
+ // Allocate dirDevMinor. lowerDevMinors are allocated dynamically.
dirDevMinor, err := vfsObj.GetAnonBlockDevMinor()
if err != nil {
return nil, nil, err
}
- lowerDevMinors := make(map[*vfs.Filesystem]uint32)
- for _, lowerRoot := range fsopts.LowerRoots {
- lowerFS := lowerRoot.Mount().Filesystem()
- if _, ok := lowerDevMinors[lowerFS]; !ok {
- devMinor, err := vfsObj.GetAnonBlockDevMinor()
- if err != nil {
- vfsObj.PutAnonBlockDevMinor(dirDevMinor)
- for _, lowerDevMinor := range lowerDevMinors {
- vfsObj.PutAnonBlockDevMinor(lowerDevMinor)
- }
- return nil, nil, err
- }
- lowerDevMinors[lowerFS] = devMinor
- }
- }
// Take extra references held by the filesystem.
if fsopts.UpperRoot.Ok() {
@@ -254,7 +251,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
opts: fsopts,
creds: creds.Fork(),
dirDevMinor: dirDevMinor,
- lowerDevMinors: lowerDevMinors,
+ lowerDevMinors: make(map[layerDevNumber]uint32),
}
fs.vfsfs.Init(vfsObj, &fstype, fs)
@@ -304,7 +301,14 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
root.ino = fs.newDirIno()
} else if !root.upperVD.Ok() {
root.devMajor = linux.UNNAMED_MAJOR
- root.devMinor = fs.lowerDevMinors[root.lowerVDs[0].Mount().Filesystem()]
+ rootDevMinor, err := fs.getLowerDevMinor(rootStat.DevMajor, rootStat.DevMinor)
+ if err != nil {
+ ctx.Infof("overlay.FilesystemType.GetFilesystem: failed to get device number for root: %v", err)
+ root.destroyLocked(ctx)
+ fs.vfsfs.DecRef(ctx)
+ return nil, nil, err
+ }
+ root.devMinor = rootDevMinor
root.ino = rootStat.Ino
} else {
root.devMajor = rootStat.DevMajor
@@ -377,6 +381,21 @@ func (fs *filesystem) newDirIno() uint64 {
return atomic.AddUint64(&fs.lastDirIno, 1)
}
+func (fs *filesystem) getLowerDevMinor(layerMajor, layerMinor uint32) (uint32, error) {
+ fs.devMu.Lock()
+ defer fs.devMu.Unlock()
+ orig := layerDevNumber{layerMajor, layerMinor}
+ if minor, ok := fs.lowerDevMinors[orig]; ok {
+ return minor, nil
+ }
+ minor, err := fs.vfsfs.VirtualFilesystem().GetAnonBlockDevMinor()
+ if err != nil {
+ return 0, err
+ }
+ fs.lowerDevMinors[orig] = minor
+ return minor, nil
+}
+
// dentry implements vfs.DentryImpl.
//
// +stateify savable
diff --git a/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go b/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go
index 760300f42..6c01b2fbf 100644
--- a/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go
+++ b/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go
@@ -124,6 +124,32 @@ func (fs *filesystem) StateLoad(stateSourceObject state.Source) {
stateSourceObject.Load(5, &fs.lastDirIno)
}
+func (l *layerDevNumber) StateTypeName() string {
+ return "pkg/sentry/fsimpl/overlay.layerDevNumber"
+}
+
+func (l *layerDevNumber) StateFields() []string {
+ return []string{
+ "major",
+ "minor",
+ }
+}
+
+func (l *layerDevNumber) beforeSave() {}
+
+func (l *layerDevNumber) StateSave(stateSinkObject state.Sink) {
+ l.beforeSave()
+ stateSinkObject.Save(0, &l.major)
+ stateSinkObject.Save(1, &l.minor)
+}
+
+func (l *layerDevNumber) afterLoad() {}
+
+func (l *layerDevNumber) StateLoad(stateSourceObject state.Source) {
+ stateSourceObject.Load(0, &l.major)
+ stateSourceObject.Load(1, &l.minor)
+}
+
func (d *dentry) StateTypeName() string {
return "pkg/sentry/fsimpl/overlay.dentry"
}
@@ -278,6 +304,7 @@ func init() {
state.Register((*FilesystemType)(nil))
state.Register((*FilesystemOptions)(nil))
state.Register((*filesystem)(nil))
+ state.Register((*layerDevNumber)(nil))
state.Register((*dentry)(nil))
state.Register((*fileDescription)(nil))
state.Register((*regularFileFD)(nil))
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 04:31:21 +0000