Move VFS2 handling of FD readability/writability to vfs.FileDescription.

PiperOrigin-RevId: 291006713

3 files changed, 8 insertions, 26 deletions

diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 4cd7e9aea..a9f66a42a 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -337,19 +337,12 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32,
 			return nil, err
 		}
 	}
-	mnt := rp.Mount()
 	switch impl := d.inode.impl.(type) {
 	case *regularFile:
 		var fd regularFileFD
-		fd.readable = vfs.MayReadFileWithOpenFlags(flags)
-		fd.writable = vfs.MayWriteFileWithOpenFlags(flags)
-		if fd.writable {
-			if err := mnt.CheckBeginWrite(); err != nil {
-				return nil, err
-			}
-			// mnt.EndWrite() is called by regularFileFD.Release().
+		if err := fd.vfsfd.Init(&fd, flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
+			return nil, err
 		}
-		fd.vfsfd.Init(&fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{})
 		if flags&linux.O_TRUNC != 0 {
 			impl.mu.Lock()
 			impl.data.Truncate(0, impl.memFile)
@@ -363,7 +356,9 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32,
 			return nil, syserror.EISDIR
 		}
 		var fd directoryFD
-		fd.vfsfd.Init(&fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{})
+		if err := fd.vfsfd.Init(&fd, 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).
diff --git a/pkg/sentry/fsimpl/tmpfs/named_pipe.go b/pkg/sentry/fsimpl/tmpfs/named_pipe.go
index 40bde54de..482aabd52 100644
--- a/pkg/sentry/fsimpl/tmpfs/named_pipe.go
+++ b/pkg/sentry/fsimpl/tmpfs/named_pipe.go
@@ -50,11 +50,10 @@ type namedPipeFD struct {
 func newNamedPipeFD(ctx context.Context, np *namedPipe, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, flags uint32) (*vfs.FileDescription, error) {
 	var err error
 	var fd namedPipeFD
-	fd.VFSPipeFD, err = np.pipe.NewVFSPipeFD(ctx, rp, vfsd, &fd.vfsfd, flags)
+	fd.VFSPipeFD, err = np.pipe.NewVFSPipeFD(ctx, vfsd, &fd.vfsfd, flags)
 	if err != nil {
 		return nil, err
 	}
-	mnt := rp.Mount()
-	fd.vfsfd.Init(&fd, flags, mnt, vfsd, &vfs.FileDescriptionOptions{})
+	fd.vfsfd.Init(&fd, flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{})
 	return &fd.vfsfd, nil
 }
diff --git a/pkg/sentry/fsimpl/tmpfs/regular_file.go b/pkg/sentry/fsimpl/tmpfs/regular_file.go
index 5fa70cc6d..7c633c1b0 100644
--- a/pkg/sentry/fsimpl/tmpfs/regular_file.go
+++ b/pkg/sentry/fsimpl/tmpfs/regular_file.go
@@ -101,10 +101,6 @@ func (rf *regularFile) truncate(size uint64) (bool, error) {
 type regularFileFD struct {
 	fileDescription
 
-	// These are immutable.
-	readable bool
-	writable bool
-
 	// off is the file offset. off is accessed using atomic memory operations.
 	// offMu serializes operations that may mutate off.
 	off   int64
@@ -113,16 +109,11 @@ type regularFileFD struct {
 
 // Release implements vfs.FileDescriptionImpl.Release.
 func (fd *regularFileFD) Release() {
-	if fd.writable {
-		fd.vfsfd.VirtualDentry().Mount().EndWrite()
-	}
+	// noop
 }
 
 // PRead implements vfs.FileDescriptionImpl.PRead.
 func (fd *regularFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
-	if !fd.readable {
-		return 0, syserror.EINVAL
-	}
 	if offset < 0 {
 		return 0, syserror.EINVAL
 	}
@@ -147,9 +138,6 @@ func (fd *regularFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts
 
 // PWrite implements vfs.FileDescriptionImpl.PWrite.
 func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
-	if !fd.writable {
-		return 0, syserror.EINVAL
-	}
 	if offset < 0 {
 		return 0, syserror.EINVAL
 	}