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

6 files changed, 17 insertions, 11 deletions

diff --git a/pkg/sentry/fsimpl/proc/BUILD b/pkg/sentry/fsimpl/proc/BUILD
index 351ba4ee9..6014138ff 100644
--- a/pkg/sentry/fsimpl/proc/BUILD
+++ b/pkg/sentry/fsimpl/proc/BUILD
@@ -22,6 +22,7 @@ go_library(
         "//pkg/log",
         "//pkg/refs",
         "//pkg/safemem",
+        "//pkg/sentry/fs/lock",
         "//pkg/sentry/fsbridge",
         "//pkg/sentry/fsimpl/kernfs",
         "//pkg/sentry/inet",
@@ -35,7 +36,6 @@ go_library(
         "//pkg/sentry/socket/unix/transport",
         "//pkg/sentry/usage",
         "//pkg/sentry/vfs",
-        "//pkg/sentry/vfs/lock",
         "//pkg/syserror",
         "//pkg/tcpip/header",
         "//pkg/usermem",
diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go
index e2cdb7ee9..36a89540c 100644
--- a/pkg/sentry/fsimpl/proc/subtasks.go
+++ b/pkg/sentry/fsimpl/proc/subtasks.go
@@ -24,7 +24,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"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"
 )
 
@@ -38,7 +37,7 @@ type subtasksInode struct {
 	kernfs.OrderedChildren
 	kernfs.AlwaysValid
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	fs                *filesystem
 	task              *kernel.Task
diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go
index 44078a765..8bb2b0ce1 100644
--- a/pkg/sentry/fsimpl/proc/task.go
+++ b/pkg/sentry/fsimpl/proc/task.go
@@ -25,7 +25,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
@@ -39,7 +38,7 @@ type taskInode struct {
 	kernfs.InodeAttrs
 	kernfs.OrderedChildren
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	task *kernel.Task
 }
diff --git a/pkg/sentry/fsimpl/proc/task_fds.go b/pkg/sentry/fsimpl/proc/task_fds.go
index ef6c1d04f..7debdb07a 100644
--- a/pkg/sentry/fsimpl/proc/task_fds.go
+++ b/pkg/sentry/fsimpl/proc/task_fds.go
@@ -27,7 +27,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"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"
 )
 
@@ -54,7 +53,7 @@ func taskFDExists(t *kernel.Task, fd int32) bool {
 }
 
 type fdDir struct {
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	fs   *filesystem
 	task *kernel.Task
diff --git a/pkg/sentry/fsimpl/proc/task_files.go b/pkg/sentry/fsimpl/proc/task_files.go
index e5eaa91cd..ba4405026 100644
--- a/pkg/sentry/fsimpl/proc/task_files.go
+++ b/pkg/sentry/fsimpl/proc/task_files.go
@@ -22,6 +22,7 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/safemem"
+	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -30,7 +31,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/mm"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
@@ -777,7 +777,7 @@ type namespaceInode struct {
 	kernfs.InodeNotDirectory
 	kernfs.InodeNotSymlink
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 }
 
 var _ kernfs.Inode = (*namespaceInode)(nil)
@@ -830,3 +830,13 @@ func (fd *namespaceFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) err
 func (fd *namespaceFD) Release() {
 	fd.inode.DecRef()
 }
+
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (fd *namespaceFD) 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 *namespaceFD) 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/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go
index 58c8b9d05..2f214d0c2 100644
--- a/pkg/sentry/fsimpl/proc/tasks.go
+++ b/pkg/sentry/fsimpl/proc/tasks.go
@@ -25,7 +25,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"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"
 )
 
@@ -44,7 +43,7 @@ type tasksInode struct {
 	kernfs.OrderedChildren
 	kernfs.AlwaysValid
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	fs    *filesystem
 	pidns *kernel.PIDNamespace