tipc: check session number before accepting link protocol messages

In some virtual environments we observe a significant higher number of
packet reordering and delays than we have been used to traditionally.

This makes it necessary with stricter checks on incoming link protocol
messages' session number, which until now only has been validated for
RESET messages.

Since the other two message types, ACTIVATE and STATE messages also
carry this number, it is easy to extend the validation check to those
messages.

We also introduce a flag indicating if a link has a valid peer session
number or not. This eliminates the mixing of 32- and 16-bit arithmethics
we are currently using to achieve this.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 1cdb176798f7..52fd80b0e728 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -1540,7 +1540,7 @@ static void tipc_node_bc_rcv(struct net *net, struct sk_buff *skb, int bearer_id
  * tipc_node_check_state - check and if necessary update node state
  * @skb: TIPC packet
  * @bearer_id: identity of bearer delivering the packet
- * Returns true if state is ok, otherwise consumes buffer and returns false
+ * Returns true if state and msg are ok, otherwise false
  */
 static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
                                   int bearer_id, struct sk_buff_head *xmitq)
@@ -1574,6 +1574,9 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
                 }
         }
 
+        if (!tipc_link_validate_msg(l, hdr))
+                return false;
+
         /* Check and update node accesibility if applicable */
         if (state == SELF_UP_PEER_COMING) {
                 if (!tipc_link_is_up(l))