ipvs: support scheduling inverse and icmp UDP packets

In the event of an icmp packet, take only the ports instead of trying to
grab the full header.

In the event of an inverse packet, use the source address and port.
Signed-off-by: Alex Gartrell <agartrell@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_proto_udp.c

@@ -36,23 +36,32 @@ udp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
 	struct net *net;
 	struct ip_vs_service *svc;
 	struct udphdr _udph, *uh;
+	__be16 _ports[2], *ports = NULL;
 
-	if (ip_vs_iph_icmp(iph)) {
-		/* TEMPORARY - do not schedule icmp yet */
-		*verdict = NF_ACCEPT;
-		return 0;
+	if (likely(!ip_vs_iph_icmp(iph))) {
+		/* IPv6 fragments, only first fragment will hit this */
+		uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
+		if (uh)
+			ports = &uh->source;
+	} else {
+		ports = skb_header_pointer(
+			skb, iph->len, sizeof(_ports), &_ports);
 	}
 
-	/* IPv6 fragments, only first fragment will hit this */
-	uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
-	if (uh == NULL) {
+	if (!ports) {
 		*verdict = NF_DROP;
 		return 0;
 	}
+
 	net = skb_net(skb);
 	rcu_read_lock();
-	svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
-				 &iph->daddr, uh->dest);
+	if (likely(!ip_vs_iph_inverse(iph)))
+		svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
+					 &iph->daddr, ports[1]);
+	else
+		svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
+					 &iph->saddr, ports[0]);
+
 	if (svc) {
 		int ignored;