NFSv4: Ensure that we check lock exclusive/shared type against open modes

commit 55725513b5ef9d462aa3e18527658a0362aaae83 upstream.

Since we may be simulating flock() locks using NFS byte range locks,
we can't rely on the VFS having checked the file open mode for us.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 57f9971..51f6a40 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4601,6 +4601,20 @@ nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)
 
        if (state == NULL)
                return -ENOLCK;
 
        if (state == NULL)
                return -ENOLCK;

+       /*
+        * Don't rely on the VFS having checked the file open mode,
+        * since it won't do this for flock() locks.
+        */
+       switch (request->fl_type & (F_RDLCK|F_WRLCK|F_UNLCK)) {
+       case F_RDLCK:
+               if (!(filp->f_mode & FMODE_READ))
+                       return -EBADF;
+               break;
+       case F_WRLCK:
+               if (!(filp->f_mode & FMODE_WRITE))
+                       return -EBADF;
+       }
+

        do {
                status = nfs4_proc_setlk(state, cmd, request);
                if ((status != -EAGAIN) || IS_SETLK(cmd))
        do {
                status = nfs4_proc_setlk(state, cmd, request);
                if ((status != -EAGAIN) || IS_SETLK(cmd))