nfs41: Backchannel: CB_SEQUENCE validation
Validates the callback's sessionID, the slot number, and the sequence ID.
Increments the slot's sequence.
Detects replays, but simply prints a debug message (if debugging is enabled
since we don't yet implement a duplicate request cache for the backchannel.
This should not present a problem, since only idempotent callbacks are
currently implemented.
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfs41: Backchannel: Be more obvious about the return value]
[nfs41: Backchannel: dprink in host order]
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 6b342e8..b7da1f5 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -105,6 +105,57 @@
#if defined(CONFIG_NFS_V4_1)
/*
+ * Validate the sequenceID sent by the server.
+ * Return success if the sequenceID is one more than what we last saw on
+ * this slot, accounting for wraparound. Increments the slot's sequence.
+ *
+ * We don't yet implement a duplicate request cache, so at this time
+ * we will log replays, and process them as if we had not seen them before,
+ * but we don't bump the sequence in the slot. Not too worried about it,
+ * since we only currently implement idempotent callbacks anyway.
+ *
+ * We have a single slot backchannel at this time, so we don't bother
+ * checking the used_slots bit array on the table. The lower layer guarantees
+ * a single outstanding callback request at a time.
+ */
+static int
+validate_seqid(struct nfs4_slot_table *tbl, u32 slotid, u32 seqid)
+{
+ struct nfs4_slot *slot;
+
+ dprintk("%s enter. slotid %d seqid %d\n",
+ __func__, slotid, seqid);
+
+ if (slotid > NFS41_BC_MAX_CALLBACKS)
+ return htonl(NFS4ERR_BADSLOT);
+
+ slot = tbl->slots + slotid;
+ dprintk("%s slot table seqid: %d\n", __func__, slot->seq_nr);
+
+ /* Normal */
+ if (likely(seqid == slot->seq_nr + 1)) {
+ slot->seq_nr++;
+ return htonl(NFS4_OK);
+ }
+
+ /* Replay */
+ if (seqid == slot->seq_nr) {
+ dprintk("%s seqid %d is a replay - no DRC available\n",
+ __func__, seqid);
+ return htonl(NFS4_OK);
+ }
+
+ /* Wraparound */
+ if (seqid == 1 && (slot->seq_nr + 1) == 0) {
+ slot->seq_nr = 1;
+ return htonl(NFS4_OK);
+ }
+
+ /* Misordered request */
+ return htonl(NFS4ERR_SEQ_MISORDERED);
+}
+
+/*
* Returns a pointer to a held 'struct nfs_client' that matches the server's
* address, major version number, and session ID. It is the caller's
* responsibility to release the returned reference.
@@ -140,18 +191,27 @@
return NULL;
}
-/* FIXME: validate args->cbs_{sequence,slot}id */
/* FIXME: referring calls should be processed */
unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
struct cb_sequenceres *res)
{
- int i;
- unsigned status = 0;
+ struct nfs_client *clp;
+ int i, status;
for (i = 0; i < args->csa_nrclists; i++)
kfree(args->csa_rclists[i].rcl_refcalls);
kfree(args->csa_rclists);
+ status = htonl(NFS4ERR_BADSESSION);
+ clp = find_client_with_session(args->csa_addr, 4, &args->csa_sessionid);
+ if (clp == NULL)
+ goto out;
+
+ status = validate_seqid(&clp->cl_session->bc_slot_table,
+ args->csa_slotid, args->csa_sequenceid);
+ if (status)
+ goto out_putclient;
+
memcpy(&res->csr_sessionid, &args->csa_sessionid,
sizeof(res->csr_sessionid));
res->csr_sequenceid = args->csa_sequenceid;
@@ -159,9 +219,12 @@
res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
+out_putclient:
+ nfs_put_client(clp);
+out:
dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
res->csr_status = status;
- return status;
+ return res->csr_status;
}
#endif /* CONFIG_NFS_V4_1 */