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, 16 insertions, 0 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 85108cfbb1ae..d9a0e74d8923 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -326,6 +326,22 @@ static __inline__ void inet_reset_saddr(struct sock *sk)
 
 #endif
 
+static inline int sk_mc_loop(struct sock *sk)
+{
+        if (!sk)
+                return 1;
+        switch (sk->sk_family) {
+        case AF_INET:
+                return inet_sk(sk)->mc_loop;
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+        case AF_INET6:
+                return inet6_sk(sk)->mc_loop;
+#endif
+        }
+        __WARN();
+        return 1;
+}
+
 extern int      ip_call_ra_chain(struct sk_buff *skb);
 
 /*