net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup

ipv6_stub uses the ip6_dst_lookup function to allow other modules to
perform IPv6 lookups. However, this function skips the XFRM layer
entirely.

All users of ipv6_stub->ip6_dst_lookup use ip_route_output_flow (via the
ip_route_output_key and ip_route_output helpers) for their IPv4 lookups,
which calls xfrm_lookup_route(). This patch fixes this inconsistent
behavior by switching the stub to ip6_dst_lookup_flow, which also calls
xfrm_lookup_route().

This requires some changes in all the callers, as these two functions
take different arguments and have different return types.

Fixes: 5f81bd2e5d ("ipv6: export a stub for IPv6 symbols used by vxlan")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/udp_media.c

@@ -195,10 +195,13 @@ static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 				.saddr = src->ipv6,
 				.flowi6_proto = IPPROTO_UDP
 			};
-			err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk,
-							 &ndst, &fl6);
-			if (err)
+			ndst = ipv6_stub->ipv6_dst_lookup_flow(net,
+							       ub->ubsock->sk,
+							       &fl6, NULL);
+			if (IS_ERR(ndst)) {
+				err = PTR_ERR(ndst);
 				goto tx_error;
+			}
 			dst_cache_set_ip6(cache, ndst, &fl6.saddr);
 		}
 		ttl = ip6_dst_hoplimit(ndst);