[ 090/167] [PATCH] NFSv4: Ensure that we check lock exclusive/shared type against open modes

Ben Hutchings
2012-05-09T06:09:13Z

From: Trond Myklebust <Trond.Myklebust@netapp.com>

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

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 3c787d0..ba837d9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4726,6 +4726,20 @@ nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)

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))
--
1.7.10