Resolve remaining O_PATH TODOs.

O_PATH is now implemented in vfs2.

Fixes #2782.

PiperOrigin-RevId: 373861410

7 files changed, 95 insertions, 34 deletions

diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 97ce80853..91ec4a142 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -961,7 +961,7 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open
 		}
 		return &fd.vfsfd, nil
 	case linux.S_IFLNK:
-		// Can't open symlinks without O_PATH (which is unimplemented).
+		// Can't open symlinks without O_PATH, which is handled at the VFS layer.
 		return nil, syserror.ELOOP
 	case linux.S_IFSOCK:
 		if d.isSynthetic() {
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 5fdca1d46..766289e60 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -465,7 +465,7 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open
 		}
 		return &fd.vfsfd, nil
 	case *symlink:
-		// TODO(gvisor.dev/issue/2782): Can't open symlinks without O_PATH.
+		// Can't open symlinks without O_PATH, which is handled at the VFS layer.
 		return nil, syserror.ELOOP
 	case *namedPipe:
 		return impl.pipe.Open(ctx, rp.Mount(), &d.vfsd, opts.Flags, &d.inode.locks)
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index 31d34ef60..fa7696ad6 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -1299,6 +1299,11 @@ func (fd *fileDescription) ConfigureMMap(ctx context.Context, opts *memmap.MMapO
 	return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
 }
 
+// SupportsLocks implements vfs.FileDescriptionImpl.SupportsLocks.
+func (fd *fileDescription) SupportsLocks() bool {
+	return fd.lowerFD.SupportsLocks()
+}
+
 // LockBSD implements vfs.FileDescriptionImpl.LockBSD.
 func (fd *fileDescription) LockBSD(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, block fslock.Blocker) error {
 	return fd.lowerFD.LockBSD(ctx, ownerPID, t, block)
diff --git a/pkg/sentry/kernel/fd_table.go b/pkg/sentry/kernel/fd_table.go
index 10885688c..62777faa8 100644
--- a/pkg/sentry/kernel/fd_table.go
+++ b/pkg/sentry/kernel/fd_table.go
@@ -154,9 +154,11 @@ func (f *FDTable) drop(ctx context.Context, file *fs.File) {
 // dropVFS2 drops the table reference.
 func (f *FDTable) dropVFS2(ctx context.Context, file *vfs.FileDescription) {
 	// Release any POSIX lock possibly held by the FDTable.
-	err := file.UnlockPOSIX(ctx, f, lock.LockRange{0, lock.LockEOF})
-	if err != nil && err != syserror.ENOLCK {
-		panic(fmt.Sprintf("UnlockPOSIX failed: %v", err))
+	if file.SupportsLocks() {
+		err := file.UnlockPOSIX(ctx, f, lock.LockRange{0, lock.LockEOF})
+		if err != nil && err != syserror.ENOLCK {
+			panic(fmt.Sprintf("UnlockPOSIX failed: %v", err))
+		}
 	}
 
 	// Drop the table's reference.
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 176bcc242..ef8d8a813 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -454,6 +454,9 @@ type FileDescriptionImpl interface {
 	// RemoveXattr removes the given extended attribute from the file.
 	RemoveXattr(ctx context.Context, name string) error
 
+	// SupportsLocks indicates whether file locks are supported.
+	SupportsLocks() bool
+
 	// LockBSD tries to acquire a BSD-style advisory file lock.
 	LockBSD(ctx context.Context, uid lock.UniqueID, ownerPID int32, t lock.LockType, block lock.Blocker) error
 
@@ -818,6 +821,11 @@ func (fd *FileDescription) Msync(ctx context.Context, mr memmap.MappableRange) e
 	return fd.Sync(ctx)
 }
 
+// SupportsLocks indicates whether file locks are supported.
+func (fd *FileDescription) SupportsLocks() bool {
+	return fd.impl.SupportsLocks()
+}
+
 // LockBSD tries to acquire a BSD-style advisory file lock.
 func (fd *FileDescription) LockBSD(ctx context.Context, ownerPID int32, lockType lock.LockType, blocker lock.Blocker) error {
 	atomic.StoreUint32(&fd.usedLockBSD, 1)
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index b87d9690a..2b6f47b4b 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -413,6 +413,11 @@ type LockFD struct {
 	locks *FileLocks
 }
 
+// SupportsLocks implements FileDescriptionImpl.SupportsLocks.
+func (LockFD) SupportsLocks() bool {
+	return true
+}
+
 // Init initializes fd with FileLocks to use.
 func (fd *LockFD) Init(locks *FileLocks) {
 	fd.locks = locks
@@ -423,28 +428,28 @@ func (fd *LockFD) Locks() *FileLocks {
 	return fd.locks
 }
 
-// LockBSD implements vfs.FileDescriptionImpl.LockBSD.
+// LockBSD implements FileDescriptionImpl.LockBSD.
 func (fd *LockFD) LockBSD(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, block fslock.Blocker) error {
 	return fd.locks.LockBSD(ctx, uid, ownerPID, t, block)
 }
 
-// UnlockBSD implements vfs.FileDescriptionImpl.UnlockBSD.
+// UnlockBSD implements FileDescriptionImpl.UnlockBSD.
 func (fd *LockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
 	fd.locks.UnlockBSD(uid)
 	return nil
 }
 
-// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+// LockPOSIX implements FileDescriptionImpl.LockPOSIX.
 func (fd *LockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
 	return fd.locks.LockPOSIX(ctx, uid, ownerPID, t, r, block)
 }
 
-// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+// UnlockPOSIX implements FileDescriptionImpl.UnlockPOSIX.
 func (fd *LockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
 	return fd.locks.UnlockPOSIX(ctx, uid, r)
 }
 
-// TestPOSIX implements vfs.FileDescriptionImpl.TestPOSIX.
+// TestPOSIX implements FileDescriptionImpl.TestPOSIX.
 func (fd *LockFD) TestPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange) (linux.Flock, error) {
 	return fd.locks.TestPOSIX(ctx, uid, t, r)
 }
@@ -455,27 +460,68 @@ func (fd *LockFD) TestPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.L
 // +stateify savable
 type NoLockFD struct{}
 
-// LockBSD implements vfs.FileDescriptionImpl.LockBSD.
+// SupportsLocks implements FileDescriptionImpl.SupportsLocks.
+func (NoLockFD) SupportsLocks() bool {
+	return false
+}
+
+// LockBSD implements FileDescriptionImpl.LockBSD.
 func (NoLockFD) LockBSD(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, block fslock.Blocker) error {
 	return syserror.ENOLCK
 }
 
-// UnlockBSD implements vfs.FileDescriptionImpl.UnlockBSD.
+// UnlockBSD implements FileDescriptionImpl.UnlockBSD.
 func (NoLockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
 	return syserror.ENOLCK
 }
 
-// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+// LockPOSIX implements FileDescriptionImpl.LockPOSIX.
 func (NoLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
 	return syserror.ENOLCK
 }
 
-// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+// UnlockPOSIX implements FileDescriptionImpl.UnlockPOSIX.
 func (NoLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
 	return syserror.ENOLCK
 }
 
-// TestPOSIX implements vfs.FileDescriptionImpl.TestPOSIX.
+// TestPOSIX implements FileDescriptionImpl.TestPOSIX.
 func (NoLockFD) TestPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange) (linux.Flock, error) {
 	return linux.Flock{}, syserror.ENOLCK
 }
+
+// BadLockFD implements Lock*/Unlock* portion of FileDescriptionImpl interface
+// returning EBADF.
+//
+// +stateify savable
+type BadLockFD struct{}
+
+// SupportsLocks implements FileDescriptionImpl.SupportsLocks.
+func (BadLockFD) SupportsLocks() bool {
+	return false
+}
+
+// LockBSD implements FileDescriptionImpl.LockBSD.
+func (BadLockFD) LockBSD(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, block fslock.Blocker) error {
+	return syserror.EBADF
+}
+
+// UnlockBSD implements FileDescriptionImpl.UnlockBSD.
+func (BadLockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
+	return syserror.EBADF
+}
+
+// LockPOSIX implements FileDescriptionImpl.LockPOSIX.
+func (BadLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, ownerPID int32, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
+	return syserror.EBADF
+}
+
+// UnlockPOSIX implements FileDescriptionImpl.UnlockPOSIX.
+func (BadLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
+	return syserror.EBADF
+}
+
+// TestPOSIX implements FileDescriptionImpl.TestPOSIX.
+func (BadLockFD) TestPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange) (linux.Flock, error) {
+	return linux.Flock{}, syserror.EBADF
+}
diff --git a/pkg/sentry/vfs/opath.go b/pkg/sentry/vfs/opath.go
index 47848c76b..e9651b631 100644
--- a/pkg/sentry/vfs/opath.go
+++ b/pkg/sentry/vfs/opath.go
@@ -24,96 +24,96 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
-// opathFD implements vfs.FileDescriptionImpl for a file description opened with O_PATH.
+// opathFD implements FileDescriptionImpl for a file description opened with O_PATH.
 //
 // +stateify savable
 type opathFD struct {
 	vfsfd FileDescription
 	FileDescriptionDefaultImpl
-	NoLockFD
+	BadLockFD
 }
 
-// Release implements vfs.FileDescriptionImpl.Release.
+// Release implements FileDescriptionImpl.Release.
 func (fd *opathFD) Release(context.Context) {
 	// noop
 }
 
-// Allocate implements vfs.FileDescriptionImpl.Allocate.
+// Allocate implements FileDescriptionImpl.Allocate.
 func (fd *opathFD) Allocate(ctx context.Context, mode, offset, length uint64) error {
 	return syserror.EBADF
 }
 
-// PRead implements vfs.FileDescriptionImpl.PRead.
+// PRead implements FileDescriptionImpl.PRead.
 func (fd *opathFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) {
 	return 0, syserror.EBADF
 }
 
-// Read implements vfs.FileDescriptionImpl.Read.
+// Read implements FileDescriptionImpl.Read.
 func (fd *opathFD) Read(ctx context.Context, dst usermem.IOSequence, opts ReadOptions) (int64, error) {
 	return 0, syserror.EBADF
 }
 
-// PWrite implements vfs.FileDescriptionImpl.PWrite.
+// PWrite implements FileDescriptionImpl.PWrite.
 func (fd *opathFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts WriteOptions) (int64, error) {
 	return 0, syserror.EBADF
 }
 
-// Write implements vfs.FileDescriptionImpl.Write.
+// Write implements FileDescriptionImpl.Write.
 func (fd *opathFD) Write(ctx context.Context, src usermem.IOSequence, opts WriteOptions) (int64, error) {
 	return 0, syserror.EBADF
 }
 
-// Ioctl implements vfs.FileDescriptionImpl.Ioctl.
+// Ioctl implements FileDescriptionImpl.Ioctl.
 func (fd *opathFD) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	return 0, syserror.EBADF
 }
 
-// IterDirents implements vfs.FileDescriptionImpl.IterDirents.
+// IterDirents implements FileDescriptionImpl.IterDirents.
 func (fd *opathFD) IterDirents(ctx context.Context, cb IterDirentsCallback) error {
 	return syserror.EBADF
 }
 
-// Seek implements vfs.FileDescriptionImpl.Seek.
+// Seek implements FileDescriptionImpl.Seek.
 func (fd *opathFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
 	return 0, syserror.EBADF
 }
 
-// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
+// ConfigureMMap implements FileDescriptionImpl.ConfigureMMap.
 func (fd *opathFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
 	return syserror.EBADF
 }
 
-// ListXattr implements vfs.FileDescriptionImpl.ListXattr.
+// ListXattr implements FileDescriptionImpl.ListXattr.
 func (fd *opathFD) ListXattr(ctx context.Context, size uint64) ([]string, error) {
 	return nil, syserror.EBADF
 }
 
-// GetXattr implements vfs.FileDescriptionImpl.GetXattr.
+// GetXattr implements FileDescriptionImpl.GetXattr.
 func (fd *opathFD) GetXattr(ctx context.Context, opts GetXattrOptions) (string, error) {
 	return "", syserror.EBADF
 }
 
-// SetXattr implements vfs.FileDescriptionImpl.SetXattr.
+// SetXattr implements FileDescriptionImpl.SetXattr.
 func (fd *opathFD) SetXattr(ctx context.Context, opts SetXattrOptions) error {
 	return syserror.EBADF
 }
 
-// RemoveXattr implements vfs.FileDescriptionImpl.RemoveXattr.
+// RemoveXattr implements FileDescriptionImpl.RemoveXattr.
 func (fd *opathFD) RemoveXattr(ctx context.Context, name string) error {
 	return syserror.EBADF
 }
 
-// Sync implements vfs.FileDescriptionImpl.Sync.
+// Sync implements FileDescriptionImpl.Sync.
 func (fd *opathFD) Sync(ctx context.Context) error {
 	return syserror.EBADF
 }
 
-// SetStat implements vfs.FileDescriptionImpl.SetStat.
+// SetStat implements FileDescriptionImpl.SetStat.
 func (fd *opathFD) SetStat(ctx context.Context, opts SetStatOptions) error {
 	return syserror.EBADF
 }
 
-// Stat implements vfs.FileDescriptionImpl.Stat.
+// Stat implements FileDescriptionImpl.Stat.
 func (fd *opathFD) Stat(ctx context.Context, opts StatOptions) (linux.Statx, error) {
 	vfsObj := fd.vfsfd.vd.mount.vfs
 	rp := vfsObj.getResolvingPath(auth.CredentialsFromContext(ctx), &PathOperation{