ipvs: support scheduling inverse and icmp SCTP 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: NAlex Gartrell <agartrell@fb.com>
Acked-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_proto_sctp.c

@@ -18,22 +18,24 @@ sctp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
 	struct netns_ipvs *ipvs;
 	sctp_chunkhdr_t _schunkh, *sch;
 	sctp_sctphdr_t *sh, _sctph;
-
-	if (ip_vs_iph_icmp(iph)) {
-		/* TEMPORARY - do not schedule icmp yet */
-		*verdict = NF_ACCEPT;
-		return 0;
-	}
-
-	sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph);
-	if (sh == NULL) {
-		*verdict = NF_DROP;
-		return 0;
+	__be16 _ports[2], *ports = NULL;
+
+	if (likely(!ip_vs_iph_icmp(iph))) {
+		sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph);
+		if (sh) {
+			sch = skb_header_pointer(
+				skb, iph->len + sizeof(sctp_sctphdr_t),
+				sizeof(_schunkh), &_schunkh);
+			if (sch && (sch->type == SCTP_CID_INIT ||
+				    sysctl_sloppy_sctp(ipvs)))
+				ports = &sh->source;
+		}
+	} else {
+		ports = skb_header_pointer(
+			skb, iph->len, sizeof(_ports), &_ports);
 	}
 
-	sch = skb_header_pointer(skb, iph->len + sizeof(sctp_sctphdr_t),
-				 sizeof(_schunkh), &_schunkh);
-	if (sch == NULL) {
+	if (!ports) {
 		*verdict = NF_DROP;
 		return 0;
 	}
@@ -41,9 +43,13 @@ sctp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
 	net = skb_net(skb);
 	ipvs = net_ipvs(net);
 	rcu_read_lock();
-	if ((sch->type == SCTP_CID_INIT || sysctl_sloppy_sctp(ipvs)) &&
-	    (svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
-				      &iph->daddr, sh->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;
 
 		if (ip_vs_todrop(ipvs)) {