Merge branch 'sctp-src-addr'

Marcelo Ricardo Leitner says:

====================
sctp: fix src address selection if using secondary address

This series improves the way SCTP chooses its src address so that the
choosen one will always belong to the interface being used for output.

v1->v2:
 - split out the refactoring from the fix itself
 - Doing a full reverse routing as in v1 is not necessary. Only looking
   for the interface that has the address and comparing its number is
   enough.
====================
Acked-by: NVlad Yasevich <vyasevich@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/protocol.c

@@ -487,23 +487,35 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 	 */
 	rcu_read_lock();
 	list_for_each_entry_rcu(laddr, &bp->address_list, list) {
+		struct net_device *odev;
+
 		if (!laddr->valid)
 			continue;
-		if ((laddr->state == SCTP_ADDR_SRC) &&
-		    (AF_INET == laddr->a.sa.sa_family)) {
-			fl4->fl4_sport = laddr->a.v4.sin_port;
-			flowi4_update_output(fl4,
-					     asoc->base.sk->sk_bound_dev_if,
-					     RT_CONN_FLAGS(asoc->base.sk),
-					     daddr->v4.sin_addr.s_addr,
-					     laddr->a.v4.sin_addr.s_addr);
-
-			rt = ip_route_output_key(sock_net(sk), fl4);
-			if (!IS_ERR(rt)) {
-				dst = &rt->dst;
-				goto out_unlock;
-			}
-		}
+		if (laddr->state != SCTP_ADDR_SRC ||
+		    AF_INET != laddr->a.sa.sa_family)
+			continue;
+
+		fl4->fl4_sport = laddr->a.v4.sin_port;
+		flowi4_update_output(fl4,
+				     asoc->base.sk->sk_bound_dev_if,
+				     RT_CONN_FLAGS(asoc->base.sk),
+				     daddr->v4.sin_addr.s_addr,
+				     laddr->a.v4.sin_addr.s_addr);
+
+		rt = ip_route_output_key(sock_net(sk), fl4);
+		if (IS_ERR(rt))
+			continue;
+
+		/* Ensure the src address belongs to the output
+		 * interface.
+		 */
+		odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr,
+				     false);
+		if (!odev || odev->ifindex != fl4->flowi4_oif)
+			continue;
+
+		dst = &rt->dst;
+		break;
 	}
 
 out_unlock: