nfs41: verify CB_SEQUENCE position in callback compound

CB_SEQUENCE must appear first in the callback compound RPC.
If it is not the first operation NFS4ERR_SEQUENCE_POS must be returned.
If the first operation ni the CB_COMPOUND is not CB_SEQUENCE then
NFS4ERR_OP_NOT_IN_SESSION must be returned.

Signed-off-by: Ricardo Labiaga <ricardo.labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfs41: refactor op preprocessing out of process_op]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 56a3cc51010..537f21da6e5 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -521,6 +521,14 @@ out:
 static __be32
 preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
 {
+        if (op_nr == OP_CB_SEQUENCE) {
+                if (nop != 0)
+                        return htonl(NFS4ERR_SEQUENCE_POS);
+        } else {
+                if (nop == 0)
+                        return htonl(NFS4ERR_OP_NOT_IN_SESSION);
+        }
+
         switch (op_nr) {
         case OP_CB_GETATTR:
         case OP_CB_RECALL: