tipc: add loopback device tracking

Since node internal messages are passed directly to the socket, it is not
possible to observe those messages via tcpdump or wireshark.

We now remedy this by making it possible to clone such messages and send
the clones to the loopback interface.  The clones are dropped at reception
and have no functional role except making the traffic visible.

The feature is enabled if network taps are active for the loopback device.
pcap filtering restrictions require the messages to be presented to the
receiving side of the loopback device.

v3 - Function dev_nit_active used to check for network taps.
   - Procedure netif_rx_ni used to send cloned messages to loopback device.

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

1 files changed, 3 insertions, 1 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 1336f3cdad38..34f3e5641438 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -406,8 +406,10 @@ int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts,
                         rc = tipc_bcast_xmit(net, pkts, cong_link_cnt);
         }
 
-        if (dests->local)
+        if (dests->local) {
+                tipc_loopback_trace(net, &localq);
                 tipc_sk_mcast_rcv(net, &localq, &inputq);
+        }
 exit:
         /* This queue should normally be empty by now */
         __skb_queue_purge(pkts);