[ 03/47] NFSv4: Ensure that we check lock exclusive/shared type against open modes

From: Greg KH
Date: Fri May 04 2012 - 17:01:24 EST


3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/nfs/nfs4proc.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4558,6 +4558,20 @@ nfs4_proc_lock(struct file *filp, int cm

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))


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