ip: fix mc_loop checks for tunnels with multicast outer addresses

When we have L3 tunnels with different inner/outer families
(i.e. IPV4/IPV6) which use a multicast address as the outer tunnel
destination address, multicast packets will be loopbacked back to the
sending socket even if IP*_MULTICAST_LOOP is set to disabled.

The mc_loop flag is present in the family specific part of the socket
(e.g. the IPv4 or IPv4 specific part).  setsockopt sets the inner
family mc_loop flag. When the packet is pushed through the L3 tunnel
it will eventually be processed by the outer family which if different
will check the flag in a different part of the socket then it was set.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index e34013a78ef4..3451799e3dbf 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -254,7 +254,7 @@ int ip_mc_output(struct sk_buff *skb)
          */
 
         if (rt->rt_flags&RTCF_MULTICAST) {
-                if ((!sk || inet_sk(sk)->mc_loop)
+                if (sk_mc_loop(sk)
 #ifdef CONFIG_IP_MROUTE
                 /* Small optimization: do not loopback not local frames,
                    which returned after forwarding; they will be  dropped