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

2 files changed, 14 insertions, 4 deletions

diff --git a/pkg/sentry/socket/unix/BUILD b/pkg/sentry/socket/unix/BUILD
index 7d4cc80fe..cca5e70f1 100644
--- a/pkg/sentry/socket/unix/BUILD
+++ b/pkg/sentry/socket/unix/BUILD
@@ -21,6 +21,7 @@ go_library(
         "//pkg/sentry/device",
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/fsutil",
+        "//pkg/sentry/fs/lock",
         "//pkg/sentry/fsimpl/sockfs",
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/time",
@@ -29,7 +30,6 @@ go_library(
         "//pkg/sentry/socket/netstack",
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/vfs",
-        "//pkg/sentry/vfs/lock",
         "//pkg/syserr",
         "//pkg/syserror",
         "//pkg/tcpip",
diff --git a/pkg/sentry/socket/unix/unix_vfs2.go b/pkg/sentry/socket/unix/unix_vfs2.go
index 8c32371a2..ff2149250 100644
--- a/pkg/sentry/socket/unix/unix_vfs2.go
+++ b/pkg/sentry/socket/unix/unix_vfs2.go
@@ -19,6 +19,7 @@ import (
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
+	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/sockfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/socket"
@@ -26,7 +27,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/socket/netstack"
 	"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserr"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -53,7 +53,7 @@ func NewSockfsFile(t *kernel.Task, ep transport.Endpoint, stype linux.SockType)
 	mnt := t.Kernel().SocketMount()
 	d := sockfs.NewDentry(t.Credentials(), mnt)
 
-	fd, err := NewFileDescription(ep, stype, linux.O_RDWR, mnt, d, &lock.FileLocks{})
+	fd, err := NewFileDescription(ep, stype, linux.O_RDWR, mnt, d, &vfs.FileLocks{})
 	if err != nil {
 		return nil, syserr.FromError(err)
 	}
@@ -62,7 +62,7 @@ func NewSockfsFile(t *kernel.Task, ep transport.Endpoint, stype linux.SockType)
 
 // NewFileDescription creates and returns a socket file description
 // corresponding to the given mount and dentry.
-func NewFileDescription(ep transport.Endpoint, stype linux.SockType, flags uint32, mnt *vfs.Mount, d *vfs.Dentry, locks *lock.FileLocks) (*vfs.FileDescription, error) {
+func NewFileDescription(ep transport.Endpoint, stype linux.SockType, flags uint32, mnt *vfs.Mount, d *vfs.Dentry, locks *vfs.FileLocks) (*vfs.FileDescription, error) {
 	// You can create AF_UNIX, SOCK_RAW sockets. They're the same as
 	// SOCK_DGRAM and don't require CAP_NET_RAW.
 	if stype == linux.SOCK_RAW {
@@ -300,6 +300,16 @@ func (s *SocketVFS2) SetSockOpt(t *kernel.Task, level int, name int, optVal []by
 	return netstack.SetSockOpt(t, s, s.ep, level, name, optVal)
 }
 
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (s *SocketVFS2) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+	return s.Locks().LockPOSIX(ctx, &s.vfsfd, uid, t, start, length, whence, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (s *SocketVFS2) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+	return s.Locks().UnlockPOSIX(ctx, &s.vfsfd, uid, start, length, whence)
+}
+
 // providerVFS2 is a unix domain socket provider for VFS2.
 type providerVFS2 struct{}