Implement POSIX locks

- Change FileDescriptionImpl Lock/UnlockPOSIX signature to
  take {start,length,whence}, so the correct offset can be
  calculated in the implementations.
- Create PosixLocker interface to make it possible to share
  the same locking code from different implementations.

Closes #1480

PiperOrigin-RevId: 316910286

5 files changed, 30 insertions, 13 deletions

diff --git a/pkg/sentry/fsimpl/kernfs/BUILD b/pkg/sentry/fsimpl/kernfs/BUILD
index 0299dbde9..179df6c1e 100644
--- a/pkg/sentry/fsimpl/kernfs/BUILD
+++ b/pkg/sentry/fsimpl/kernfs/BUILD
@@ -45,11 +45,11 @@ go_library(
         "//pkg/fspath",
         "//pkg/log",
         "//pkg/refs",
+        "//pkg/sentry/fs/lock",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/memmap",
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/vfs",
-        "//pkg/sentry/vfs/lock",
         "//pkg/sync",
         "//pkg/syserror",
         "//pkg/usermem",
@@ -68,7 +68,6 @@ go_test(
         "//pkg/sentry/fsimpl/testutil",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/vfs",
-        "//pkg/sentry/vfs/lock",
         "//pkg/syserror",
         "//pkg/usermem",
         "@com_github_google_go-cmp//cmp:go_default_library",
diff --git a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
index 6418de0a3..c1215b70a 100644
--- a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
+++ b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
@@ -19,9 +19,9 @@ 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/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
@@ -39,7 +39,7 @@ type DynamicBytesFile struct {
 	InodeNotDirectory
 	InodeNotSymlink
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 	data  vfs.DynamicBytesSource
 }
 
@@ -86,7 +86,7 @@ type DynamicBytesFD struct {
 }
 
 // Init initializes a DynamicBytesFD.
-func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, locks *lock.FileLocks, flags uint32) error {
+func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, locks *vfs.FileLocks, flags uint32) error {
 	fd.LockFD.Init(locks)
 	if err := fd.vfsfd.Init(fd, flags, m, d, &vfs.FileDescriptionOptions{}); err != nil {
 		return err
@@ -135,3 +135,13 @@ func (fd *DynamicBytesFD) SetStat(context.Context, vfs.SetStatOptions) error {
 	// DynamicBytesFiles are immutable.
 	return syserror.EPERM
 }
+
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (fd *DynamicBytesFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+	return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (fd *DynamicBytesFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+	return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence)
+}
diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
index 33a5968ca..5f7853a2a 100644
--- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
@@ -19,10 +19,10 @@ 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/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
@@ -57,7 +57,7 @@ type GenericDirectoryFD struct {
 
 // NewGenericDirectoryFD creates a new GenericDirectoryFD and returns its
 // dentry.
-func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, locks *lock.FileLocks, opts *vfs.OpenOptions) (*GenericDirectoryFD, error) {
+func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) (*GenericDirectoryFD, error) {
 	fd := &GenericDirectoryFD{}
 	if err := fd.Init(children, locks, opts); err != nil {
 		return nil, err
@@ -71,7 +71,7 @@ func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildre
 // Init initializes a GenericDirectoryFD. Use it when overriding
 // GenericDirectoryFD. Caller must call fd.VFSFileDescription.Init() with the
 // correct implementation.
-func (fd *GenericDirectoryFD) Init(children *OrderedChildren, locks *lock.FileLocks, opts *vfs.OpenOptions) error {
+func (fd *GenericDirectoryFD) Init(children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) error {
 	if vfs.AccessTypesForOpenFlags(opts)&vfs.MayWrite != 0 {
 		// Can't open directories for writing.
 		return syserror.EISDIR
@@ -235,3 +235,13 @@ func (fd *GenericDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptio
 	inode := fd.vfsfd.VirtualDentry().Dentry().Impl().(*Dentry).inode
 	return inode.SetStat(ctx, fd.filesystem(), creds, opts)
 }
+
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (fd *GenericDirectoryFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+	return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (fd *GenericDirectoryFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+	return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence)
+}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 0e4927215..650bd7b88 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -23,7 +23,6 @@ import (
 	"gvisor.dev/gvisor/pkg/refs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
@@ -557,7 +556,7 @@ type StaticDirectory struct {
 	InodeNoDynamicLookup
 	OrderedChildren
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 }
 
 var _ Inode = (*StaticDirectory)(nil)
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_test.go b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
index 6749facf7..dc407eb1d 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs_test.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
@@ -27,7 +27,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
@@ -103,7 +102,7 @@ type readonlyDir struct {
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.OrderedChildren
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	dentry kernfs.Dentry
 }
@@ -133,7 +132,7 @@ type dir struct {
 	kernfs.InodeNoDynamicLookup
 	kernfs.OrderedChildren
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	fs     *filesystem
 	dentry kernfs.Dentry