[patch 21/87] nfs: Fix NFS v4 client handling of MAY_EXEC in nfs_permission.

Greg KH
2009-06-09T10:20:49Z

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2.6.29-stable review patch. If anyone has any objections, please let us know.

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

From: Frank Filz <ffilzlnx@us.ibm.com>

commit 7ee2cb7f32b299c2b06a31fde155457203e4b7dd upstream.

The problem is that permission checking is skipped if atomic open is
possible, but when exec opens a file, it just opens it O_READONLY which
means EXEC permission will not be checked at that time.

This problem is observed by the following sequence (executed as root):

mount -t nfs4 server:/ /mnt4
echo "ls" >/mnt4/foo
chmod 744 /mnt4/foo
su guest -c "mnt4/foo"

Signed-off-by: Frank Filz <ffilzlnx@us.ibm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: Eugene Teo <eugeneteo@kernel.sg>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/nfs/dir.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1943,7 +1943,8 @@ int nfs_permission(struct inode *inode,
case S_IFREG:
/* NFSv4 has atomic_open... */
if (nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN)
- && (mask & MAY_OPEN))
+ && (mask & MAY_OPEN)
+ && !(mask & MAY_EXEC))
goto out;
break;