Implement flock(2) in VFS2

LockFD is the generic implementation that can be embedded in
FileDescriptionImpl implementations. Unique lock ID is
maintained in vfs.FileDescription and is created on demand.

Updates #1480

PiperOrigin-RevId: 315604825

3 files changed, 5 insertions, 65 deletions

diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index e801680e8..72399b321 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -399,6 +399,7 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open
 	switch impl := d.inode.impl.(type) {
 	case *regularFile:
 		var fd regularFileFD
+		fd.LockFD.Init(&d.inode.locks)
 		if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
 			return nil, err
 		}
@@ -414,15 +415,16 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open
 			return nil, syserror.EISDIR
 		}
 		var fd directoryFD
+		fd.LockFD.Init(&d.inode.locks)
 		if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
 			return nil, err
 		}
 		return &fd.vfsfd, nil
 	case *symlink:
-		// Can't open symlinks without O_PATH (which is unimplemented).
+		// TODO(gvisor.dev/issue/2782): Can't open symlinks without O_PATH.
 		return nil, syserror.ELOOP
 	case *namedPipe:
-		return impl.pipe.Open(ctx, rp.Mount(), &d.vfsd, opts.Flags)
+		return impl.pipe.Open(ctx, rp.Mount(), &d.vfsd, opts.Flags, &d.inode.locks)
 	case *deviceFile:
 		return rp.VirtualFilesystem().OpenDeviceSpecialFile(ctx, rp.Mount(), &d.vfsd, impl.kind, impl.major, impl.minor, opts)
 	case *socketFile:
diff --git a/pkg/sentry/fsimpl/tmpfs/regular_file.go b/pkg/sentry/fsimpl/tmpfs/regular_file.go
index 4f2ae04d2..77447b32c 100644
--- a/pkg/sentry/fsimpl/tmpfs/regular_file.go
+++ b/pkg/sentry/fsimpl/tmpfs/regular_file.go
@@ -25,7 +25,6 @@ import (
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
@@ -366,28 +365,6 @@ func (fd *regularFileFD) Sync(ctx context.Context) error {
 	return nil
 }
 
-// LockBSD implements vfs.FileDescriptionImpl.LockBSD.
-func (fd *regularFileFD) LockBSD(ctx context.Context, uid lock.UniqueID, t lock.LockType, block lock.Blocker) error {
-	return fd.inode().lockBSD(uid, t, block)
-}
-
-// UnlockBSD implements vfs.FileDescriptionImpl.UnlockBSD.
-func (fd *regularFileFD) UnlockBSD(ctx context.Context, uid lock.UniqueID) error {
-	fd.inode().unlockBSD(uid)
-	return nil
-}
-
-// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
-func (fd *regularFileFD) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error {
-	return fd.inode().lockPOSIX(uid, t, rng, block)
-}
-
-// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
-func (fd *regularFileFD) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error {
-	fd.inode().unlockPOSIX(uid, rng)
-	return nil
-}
-
 // ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
 func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
 	file := fd.inode().impl.(*regularFile)
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index 7ce1b86c7..71a7522af 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -36,7 +36,6 @@ import (
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
-	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/time"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
@@ -311,7 +310,6 @@ type inode struct {
 	ctime int64 // nanoseconds
 	mtime int64 // nanoseconds
 
-	// Advisory file locks, which lock at the inode level.
 	locks lock.FileLocks
 
 	// Inotify watches for this inode.
@@ -539,44 +537,6 @@ func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linu
 	return nil
 }
 
-// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular.
-func (i *inode) lockBSD(uid fslock.UniqueID, t fslock.LockType, block fslock.Blocker) error {
-	switch i.impl.(type) {
-	case *regularFile:
-		return i.locks.LockBSD(uid, t, block)
-	}
-	return syserror.EBADF
-}
-
-// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular.
-func (i *inode) unlockBSD(uid fslock.UniqueID) error {
-	switch i.impl.(type) {
-	case *regularFile:
-		i.locks.UnlockBSD(uid)
-		return nil
-	}
-	return syserror.EBADF
-}
-
-// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular.
-func (i *inode) lockPOSIX(uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error {
-	switch i.impl.(type) {
-	case *regularFile:
-		return i.locks.LockPOSIX(uid, t, rng, block)
-	}
-	return syserror.EBADF
-}
-
-// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular.
-func (i *inode) unlockPOSIX(uid fslock.UniqueID, rng fslock.LockRange) error {
-	switch i.impl.(type) {
-	case *regularFile:
-		i.locks.UnlockPOSIX(uid, rng)
-		return nil
-	}
-	return syserror.EBADF
-}
-
 // allocatedBlocksForSize returns the number of 512B blocks needed to
 // accommodate the given size in bytes, as appropriate for struct
 // stat::st_blocks and struct statx::stx_blocks. (Note that this 512B block
@@ -708,6 +668,7 @@ func (i *inode) userXattrSupported() bool {
 type fileDescription struct {
 	vfsfd vfs.FileDescription
 	vfs.FileDescriptionDefaultImpl
+	vfs.LockFD
 }
 
 func (fd *fileDescription) filesystem() *filesystem {