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-rw-r--r--pkg/sentry/vfs/vfs.go743
1 files changed, 723 insertions, 20 deletions
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 4a8a69540..9015f2cc1 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -16,24 +16,44 @@
//
// Lock order:
//
-// Filesystem implementation locks
-// VirtualFilesystem.mountMu
+// EpollInstance.interestMu
+// FileDescription.epollMu
+// FilesystemImpl/FileDescriptionImpl locks
+// VirtualFilesystem.mountMu
+// Dentry.mu
+// Locks acquired by FilesystemImpls between Prepare{Delete,Rename}Dentry and Commit{Delete,Rename*}Dentry
+// VirtualFilesystem.filesystemsMu
+// EpollInstance.mu
// VirtualFilesystem.fsTypesMu
+//
+// Locking Dentry.mu in multiple Dentries requires holding
+// VirtualFilesystem.mountMu. Locking EpollInstance.interestMu in multiple
+// EpollInstances requires holding epollCycleMu.
package vfs
import (
- "sync"
+ "fmt"
+
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/fspath"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+ "gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
+ "gvisor.dev/gvisor/pkg/sync"
+ "gvisor.dev/gvisor/pkg/syserror"
)
// A VirtualFilesystem (VFS for short) combines Filesystems in trees of Mounts.
//
// There is no analogue to the VirtualFilesystem type in Linux, as the
// equivalent state in Linux is global.
+//
+// +stateify savable
type VirtualFilesystem struct {
// mountMu serializes mount mutations.
//
// mountMu is analogous to Linux's namespace_sem.
- mountMu sync.RWMutex
+ mountMu sync.Mutex `state:"nosave"`
// mounts maps (mount parent, mount point) pairs to mounts. (Since mounts
// are uniquely namespaced, including mount parent in the key correctly
@@ -52,7 +72,7 @@ type VirtualFilesystem struct {
// mountpoints maps mount points to mounts at those points in all
// namespaces. mountpoints is protected by mountMu.
//
- // mountpoints is used to find mounts that must be unmounted due to
+ // mountpoints is used to find mounts that must be umounted due to
// removal of a mount point Dentry from another mount namespace. ("A file
// or directory that is a mount point in one namespace that is not a mount
// point in another namespace, may be renamed, unlinked, or removed
@@ -62,20 +82,693 @@ type VirtualFilesystem struct {
// mountpoints is analogous to Linux's mountpoint_hashtable.
mountpoints map[*Dentry]map[*Mount]struct{}
- // fsTypes contains all FilesystemTypes that are usable in the
- // VirtualFilesystem. fsTypes is protected by fsTypesMu.
- fsTypesMu sync.RWMutex
- fsTypes map[string]FilesystemType
+ // anonMount is a Mount, not included in mounts or mountpoints,
+ // representing an anonFilesystem. anonMount is used to back
+ // VirtualDentries returned by VirtualFilesystem.NewAnonVirtualDentry().
+ // anonMount is immutable.
+ //
+ // anonMount is analogous to Linux's anon_inode_mnt.
+ anonMount *Mount
+
+ // devices contains all registered Devices. devices is protected by
+ // devicesMu.
+ devicesMu sync.RWMutex `state:"nosave"`
+ devices map[devTuple]*registeredDevice
+
+ // anonBlockDevMinor contains all allocated anonymous block device minor
+ // numbers. anonBlockDevMinorNext is a lower bound for the smallest
+ // unallocated anonymous block device number. anonBlockDevMinorNext and
+ // anonBlockDevMinor are protected by anonBlockDevMinorMu.
+ anonBlockDevMinorMu sync.Mutex `state:"nosave"`
+ anonBlockDevMinorNext uint32
+ anonBlockDevMinor map[uint32]struct{}
+
+ // fsTypes contains all registered FilesystemTypes. fsTypes is protected by
+ // fsTypesMu.
+ fsTypesMu sync.RWMutex `state:"nosave"`
+ fsTypes map[string]*registeredFilesystemType
+
+ // filesystems contains all Filesystems. filesystems is protected by
+ // filesystemsMu.
+ filesystemsMu sync.Mutex `state:"nosave"`
+ filesystems map[*Filesystem]struct{}
}
-// New returns a new VirtualFilesystem with no mounts or FilesystemTypes.
-func New() *VirtualFilesystem {
- vfs := &VirtualFilesystem{
- mountpoints: make(map[*Dentry]map[*Mount]struct{}),
- fsTypes: make(map[string]FilesystemType),
- }
+// Init initializes a new VirtualFilesystem with no mounts or FilesystemTypes.
+func (vfs *VirtualFilesystem) Init() error {
+ vfs.mountpoints = make(map[*Dentry]map[*Mount]struct{})
+ vfs.devices = make(map[devTuple]*registeredDevice)
+ vfs.anonBlockDevMinorNext = 1
+ vfs.anonBlockDevMinor = make(map[uint32]struct{})
+ vfs.fsTypes = make(map[string]*registeredFilesystemType)
+ vfs.filesystems = make(map[*Filesystem]struct{})
vfs.mounts.Init()
- return vfs
+
+ // Construct vfs.anonMount.
+ anonfsDevMinor, err := vfs.GetAnonBlockDevMinor()
+ if err != nil {
+ // This shouldn't be possible since anonBlockDevMinorNext was
+ // initialized to 1 above (no device numbers have been allocated yet).
+ panic(fmt.Sprintf("VirtualFilesystem.Init: device number allocation for anonfs failed: %v", err))
+ }
+ anonfs := anonFilesystem{
+ devMinor: anonfsDevMinor,
+ }
+ anonfs.vfsfs.Init(vfs, &anonFilesystemType{}, &anonfs)
+ defer anonfs.vfsfs.DecRef()
+ anonMount, err := vfs.NewDisconnectedMount(&anonfs.vfsfs, nil, &MountOptions{})
+ if err != nil {
+ // We should not be passing any MountOptions that would cause
+ // construction of this mount to fail.
+ panic(fmt.Sprintf("VirtualFilesystem.Init: anonfs mount failed: %v", err))
+ }
+ vfs.anonMount = anonMount
+
+ return nil
+}
+
+// PathOperation specifies the path operated on by a VFS method.
+//
+// PathOperation is passed to VFS methods by pointer to reduce memory copying:
+// it's somewhat large and should never escape. (Options structs are passed by
+// pointer to VFS and FileDescription methods for the same reason.)
+type PathOperation struct {
+ // Root is the VFS root. References on Root are borrowed from the provider
+ // of the PathOperation.
+ //
+ // Invariants: Root.Ok().
+ Root VirtualDentry
+
+ // Start is the starting point for the path traversal. References on Start
+ // are borrowed from the provider of the PathOperation (i.e. the caller of
+ // the VFS method to which the PathOperation was passed).
+ //
+ // Invariants: Start.Ok(). If Path.Absolute, then Start == Root.
+ Start VirtualDentry
+
+ // Path is the pathname traversed by this operation.
+ Path fspath.Path
+
+ // If FollowFinalSymlink is true, and the Dentry traversed by the final
+ // path component represents a symbolic link, the symbolic link should be
+ // followed.
+ FollowFinalSymlink bool
+}
+
+// AccessAt checks whether a user with creds has access to the file at
+// the given path.
+func (vfs *VirtualFilesystem) AccessAt(ctx context.Context, creds *auth.Credentials, ats AccessTypes, pop *PathOperation) error {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.AccessAt(ctx, rp, creds, ats)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// GetDentryAt returns a VirtualDentry representing the given path, at which a
+// file must exist. A reference is taken on the returned VirtualDentry.
+func (vfs *VirtualFilesystem) GetDentryAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *GetDentryOptions) (VirtualDentry, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ d, err := rp.mount.fs.impl.GetDentryAt(ctx, rp, *opts)
+ if err == nil {
+ vd := VirtualDentry{
+ mount: rp.mount,
+ dentry: d,
+ }
+ rp.mount.IncRef()
+ vfs.putResolvingPath(rp)
+ return vd, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return VirtualDentry{}, err
+ }
+ }
+}
+
+// Preconditions: pop.Path.Begin.Ok().
+func (vfs *VirtualFilesystem) getParentDirAndName(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (VirtualDentry, string, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ parent, err := rp.mount.fs.impl.GetParentDentryAt(ctx, rp)
+ if err == nil {
+ parentVD := VirtualDentry{
+ mount: rp.mount,
+ dentry: parent,
+ }
+ rp.mount.IncRef()
+ name := rp.Component()
+ vfs.putResolvingPath(rp)
+ return parentVD, name, nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.GetParentDentryAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return VirtualDentry{}, "", err
+ }
+ }
+}
+
+// LinkAt creates a hard link at newpop representing the existing file at
+// oldpop.
+func (vfs *VirtualFilesystem) LinkAt(ctx context.Context, creds *auth.Credentials, oldpop, newpop *PathOperation) error {
+ oldVD, err := vfs.GetDentryAt(ctx, creds, oldpop, &GetDentryOptions{})
+ if err != nil {
+ return err
+ }
+
+ if !newpop.Path.Begin.Ok() {
+ oldVD.DecRef()
+ if newpop.Path.Absolute {
+ return syserror.EEXIST
+ }
+ return syserror.ENOENT
+ }
+ if newpop.FollowFinalSymlink {
+ oldVD.DecRef()
+ ctx.Warningf("VirtualFilesystem.LinkAt: file creation paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, newpop)
+ for {
+ err := rp.mount.fs.impl.LinkAt(ctx, rp, oldVD)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ oldVD.DecRef()
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.LinkAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ oldVD.DecRef()
+ return err
+ }
+ }
+}
+
+// MkdirAt creates a directory at the given path.
+func (vfs *VirtualFilesystem) MkdirAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *MkdirOptions) error {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return syserror.EEXIST
+ }
+ return syserror.ENOENT
+ }
+ if pop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.MkdirAt: file creation paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+ // "Under Linux, apart from the permission bits, the S_ISVTX mode bit is
+ // also honored." - mkdir(2)
+ opts.Mode &= 0777 | linux.S_ISVTX
+
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.MkdirAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.MkdirAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// MknodAt creates a file of the given mode at the given path. It returns an
+// error from the syserror package.
+func (vfs *VirtualFilesystem) MknodAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *MknodOptions) error {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return syserror.EEXIST
+ }
+ return syserror.ENOENT
+ }
+ if pop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.MknodAt: file creation paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.MknodAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.MknodAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// BoundEndpointAt gets the bound endpoint at the given path, if one exists.
+func (vfs *VirtualFilesystem) BoundEndpointAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (transport.BoundEndpoint, error) {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return nil, syserror.ECONNREFUSED
+ }
+ return nil, syserror.ENOENT
+ }
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ bep, err := rp.mount.fs.impl.BoundEndpointAt(ctx, rp)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return bep, nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.BoundEndpointAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return nil, err
+ }
+ }
+}
+
+// OpenAt returns a FileDescription providing access to the file at the given
+// path. A reference is taken on the returned FileDescription.
+func (vfs *VirtualFilesystem) OpenAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *OpenOptions) (*FileDescription, error) {
+ // Remove:
+ //
+ // - O_CLOEXEC, which affects file descriptors and therefore must be
+ // handled outside of VFS.
+ //
+ // - Unknown flags.
+ opts.Flags &= linux.O_ACCMODE | linux.O_CREAT | linux.O_EXCL | linux.O_NOCTTY | linux.O_TRUNC | linux.O_APPEND | linux.O_NONBLOCK | linux.O_DSYNC | linux.O_ASYNC | linux.O_DIRECT | linux.O_LARGEFILE | linux.O_DIRECTORY | linux.O_NOFOLLOW | linux.O_NOATIME | linux.O_SYNC | linux.O_PATH | linux.O_TMPFILE
+ // Linux's __O_SYNC (which we call linux.O_SYNC) implies O_DSYNC.
+ if opts.Flags&linux.O_SYNC != 0 {
+ opts.Flags |= linux.O_DSYNC
+ }
+ // Linux's __O_TMPFILE (which we call linux.O_TMPFILE) must be specified
+ // with O_DIRECTORY and a writable access mode (to ensure that it fails on
+ // filesystem implementations that do not support it).
+ if opts.Flags&linux.O_TMPFILE != 0 {
+ if opts.Flags&linux.O_DIRECTORY == 0 {
+ return nil, syserror.EINVAL
+ }
+ if opts.Flags&linux.O_CREAT != 0 {
+ return nil, syserror.EINVAL
+ }
+ if opts.Flags&linux.O_ACCMODE == linux.O_RDONLY {
+ return nil, syserror.EINVAL
+ }
+ }
+ // O_PATH causes most other flags to be ignored.
+ if opts.Flags&linux.O_PATH != 0 {
+ opts.Flags &= linux.O_DIRECTORY | linux.O_NOFOLLOW | linux.O_PATH
+ }
+ // "On Linux, the following bits are also honored in mode: [S_ISUID,
+ // S_ISGID, S_ISVTX]" - open(2)
+ opts.Mode &= 0777 | linux.S_ISUID | linux.S_ISGID | linux.S_ISVTX
+
+ if opts.Flags&linux.O_NOFOLLOW != 0 {
+ pop.FollowFinalSymlink = false
+ }
+ rp := vfs.getResolvingPath(creds, pop)
+ if opts.Flags&linux.O_DIRECTORY != 0 {
+ rp.mustBeDir = true
+ rp.mustBeDirOrig = true
+ }
+ for {
+ fd, err := rp.mount.fs.impl.OpenAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+
+ if opts.FileExec {
+ if fd.Mount().flags.NoExec {
+ fd.DecRef()
+ return nil, syserror.EACCES
+ }
+
+ // Only a regular file can be executed.
+ stat, err := fd.Stat(ctx, StatOptions{Mask: linux.STATX_TYPE})
+ if err != nil {
+ fd.DecRef()
+ return nil, err
+ }
+ if stat.Mask&linux.STATX_TYPE == 0 || stat.Mode&linux.S_IFMT != linux.S_IFREG {
+ fd.DecRef()
+ return nil, syserror.EACCES
+ }
+ }
+
+ return fd, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return nil, err
+ }
+ }
+}
+
+// ReadlinkAt returns the target of the symbolic link at the given path.
+func (vfs *VirtualFilesystem) ReadlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (string, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ target, err := rp.mount.fs.impl.ReadlinkAt(ctx, rp)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return target, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return "", err
+ }
+ }
+}
+
+// RenameAt renames the file at oldpop to newpop.
+func (vfs *VirtualFilesystem) RenameAt(ctx context.Context, creds *auth.Credentials, oldpop, newpop *PathOperation, opts *RenameOptions) error {
+ if !oldpop.Path.Begin.Ok() {
+ if oldpop.Path.Absolute {
+ return syserror.EBUSY
+ }
+ return syserror.ENOENT
+ }
+ if oldpop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.RenameAt: source path can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ oldParentVD, oldName, err := vfs.getParentDirAndName(ctx, creds, oldpop)
+ if err != nil {
+ return err
+ }
+ if oldName == "." || oldName == ".." {
+ oldParentVD.DecRef()
+ return syserror.EBUSY
+ }
+
+ if !newpop.Path.Begin.Ok() {
+ oldParentVD.DecRef()
+ if newpop.Path.Absolute {
+ return syserror.EBUSY
+ }
+ return syserror.ENOENT
+ }
+ if newpop.FollowFinalSymlink {
+ oldParentVD.DecRef()
+ ctx.Warningf("VirtualFilesystem.RenameAt: destination path can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, newpop)
+ renameOpts := *opts
+ if oldpop.Path.Dir {
+ renameOpts.MustBeDir = true
+ }
+ for {
+ err := rp.mount.fs.impl.RenameAt(ctx, rp, oldParentVD, oldName, renameOpts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ oldParentVD.DecRef()
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.RenameAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ oldParentVD.DecRef()
+ return err
+ }
+ }
+}
+
+// RmdirAt removes the directory at the given path.
+func (vfs *VirtualFilesystem) RmdirAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) error {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return syserror.EBUSY
+ }
+ return syserror.ENOENT
+ }
+ if pop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.RmdirAt: file deletion paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.RmdirAt(ctx, rp)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.RmdirAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// SetStatAt changes metadata for the file at the given path.
+func (vfs *VirtualFilesystem) SetStatAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *SetStatOptions) error {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.SetStatAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// StatAt returns metadata for the file at the given path.
+func (vfs *VirtualFilesystem) StatAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *StatOptions) (linux.Statx, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ stat, err := rp.mount.fs.impl.StatAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return stat, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return linux.Statx{}, err
+ }
+ }
+}
+
+// StatFSAt returns metadata for the filesystem containing the file at the
+// given path.
+func (vfs *VirtualFilesystem) StatFSAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (linux.Statfs, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ statfs, err := rp.mount.fs.impl.StatFSAt(ctx, rp)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return statfs, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return linux.Statfs{}, err
+ }
+ }
+}
+
+// SymlinkAt creates a symbolic link at the given path with the given target.
+func (vfs *VirtualFilesystem) SymlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, target string) error {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return syserror.EEXIST
+ }
+ return syserror.ENOENT
+ }
+ if pop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.SymlinkAt: file creation paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.SymlinkAt(ctx, rp, target)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.SymlinkAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// UnlinkAt deletes the non-directory file at the given path.
+func (vfs *VirtualFilesystem) UnlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) error {
+ if !pop.Path.Begin.Ok() {
+ if pop.Path.Absolute {
+ return syserror.EBUSY
+ }
+ return syserror.ENOENT
+ }
+ if pop.FollowFinalSymlink {
+ ctx.Warningf("VirtualFilesystem.UnlinkAt: file deletion paths can't follow final symlink")
+ return syserror.EINVAL
+ }
+
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.UnlinkAt(ctx, rp)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if checkInvariants {
+ if rp.canHandleError(err) && rp.Done() {
+ panic(fmt.Sprintf("%T.UnlinkAt() consumed all path components and returned %v", rp.mount.fs.impl, err))
+ }
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// ListxattrAt returns all extended attribute names for the file at the given
+// path.
+func (vfs *VirtualFilesystem) ListxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, size uint64) ([]string, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ names, err := rp.mount.fs.impl.ListxattrAt(ctx, rp, size)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return names, nil
+ }
+ if err == syserror.ENOTSUP {
+ // Linux doesn't actually return ENOTSUP in this case; instead,
+ // fs/xattr.c:vfs_listxattr() falls back to allowing the security
+ // subsystem to return security extended attributes, which by
+ // default don't exist.
+ vfs.putResolvingPath(rp)
+ return nil, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return nil, err
+ }
+ }
+}
+
+// GetxattrAt returns the value associated with the given extended attribute
+// for the file at the given path.
+func (vfs *VirtualFilesystem) GetxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *GetxattrOptions) (string, error) {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ val, err := rp.mount.fs.impl.GetxattrAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return val, nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return "", err
+ }
+ }
+}
+
+// SetxattrAt changes the value associated with the given extended attribute
+// for the file at the given path.
+func (vfs *VirtualFilesystem) SetxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *SetxattrOptions) error {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.SetxattrAt(ctx, rp, *opts)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// RemovexattrAt removes the given extended attribute from the file at rp.
+func (vfs *VirtualFilesystem) RemovexattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, name string) error {
+ rp := vfs.getResolvingPath(creds, pop)
+ for {
+ err := rp.mount.fs.impl.RemovexattrAt(ctx, rp, name)
+ if err == nil {
+ vfs.putResolvingPath(rp)
+ return nil
+ }
+ if !rp.handleError(err) {
+ vfs.putResolvingPath(rp)
+ return err
+ }
+ }
+}
+
+// SyncAllFilesystems has the semantics of Linux's sync(2).
+func (vfs *VirtualFilesystem) SyncAllFilesystems(ctx context.Context) error {
+ fss := make(map[*Filesystem]struct{})
+ vfs.filesystemsMu.Lock()
+ for fs := range vfs.filesystems {
+ if !fs.TryIncRef() {
+ continue
+ }
+ fss[fs] = struct{}{}
+ }
+ vfs.filesystemsMu.Unlock()
+ var retErr error
+ for fs := range fss {
+ if err := fs.impl.Sync(ctx); err != nil && retErr == nil {
+ retErr = err
+ }
+ fs.DecRef()
+ }
+ return retErr
}
// A VirtualDentry represents a node in a VFS tree, by combining a Dentry
@@ -97,11 +790,21 @@ func New() *VirtualFilesystem {
// VirtualDentry methods require that a reference is held on the VirtualDentry.
//
// VirtualDentry is analogous to Linux's struct path.
+//
+// +stateify savable
type VirtualDentry struct {
mount *Mount
dentry *Dentry
}
+// MakeVirtualDentry creates a VirtualDentry.
+func MakeVirtualDentry(mount *Mount, dentry *Dentry) VirtualDentry {
+ return VirtualDentry{
+ mount: mount,
+ dentry: dentry,
+ }
+}
+
// Ok returns true if vd is not empty. It does not require that a reference is
// held.
func (vd VirtualDentry) Ok() bool {
@@ -111,15 +814,15 @@ func (vd VirtualDentry) Ok() bool {
// IncRef increments the reference counts on the Mount and Dentry represented
// by vd.
func (vd VirtualDentry) IncRef() {
- vd.mount.incRef()
- vd.dentry.incRef(vd.mount.fs)
+ vd.mount.IncRef()
+ vd.dentry.IncRef()
}
// DecRef decrements the reference counts on the Mount and Dentry represented
// by vd.
func (vd VirtualDentry) DecRef() {
- vd.dentry.decRef(vd.mount.fs)
- vd.mount.decRef()
+ vd.dentry.DecRef()
+ vd.mount.DecRef()
}
// Mount returns the Mount associated with vd. It does not take a reference on
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-20 18:29:18 +0000