netfilter: ipvs: merge ipv4 + ipv6 icmp reply handlers

Similar to earlier patches: allow ipv4 and ipv6 to use the
same handler.  ipv4 and ipv6 specific actions can be done by
checking state->pf.

v2: split the pf == NFPROTO_IPV4 check (Julian Anastasov)
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipvs/ip_vs_core.c

@@ -2106,40 +2106,31 @@ static unsigned int
 ip_vs_forward_icmp(void *priv, struct sk_buff *skb,
 		   const struct nf_hook_state *state)
 {
-	int r;
 	struct netns_ipvs *ipvs = net_ipvs(state->net);
-
-	if (ip_hdr(skb)->protocol != IPPROTO_ICMP)
-		return NF_ACCEPT;
+	int r;
 
 	/* ipvs enabled in this netns ? */
 	if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable))
 		return NF_ACCEPT;
 
-	return ip_vs_in_icmp(ipvs, skb, &r, state->hook);
-}
-
+	if (state->pf == NFPROTO_IPV4) {
+		if (ip_hdr(skb)->protocol != IPPROTO_ICMP)
+			return NF_ACCEPT;
 #ifdef CONFIG_IP_VS_IPV6
-static unsigned int
-ip_vs_forward_icmp_v6(void *priv, struct sk_buff *skb,
-		      const struct nf_hook_state *state)
-{
-	int r;
-	struct netns_ipvs *ipvs = net_ipvs(state->net);
+	} else {
 		struct ip_vs_iphdr iphdr;
 
 		ip_vs_fill_iph_skb(AF_INET6, skb, false, &iphdr);
-	if (iphdr.protocol != IPPROTO_ICMPV6)
-		return NF_ACCEPT;
 
-	/* ipvs enabled in this netns ? */
-	if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable))
+		if (iphdr.protocol != IPPROTO_ICMPV6)
 			return NF_ACCEPT;
 
 		return ip_vs_in_icmp_v6(ipvs, skb, &r, state->hook, &iphdr);
-}
 #endif
+	}
 
+	return ip_vs_in_icmp(ipvs, skb, &r, state->hook);
+}
 
 static const struct nf_hook_ops ip_vs_ops4[] = {
 	/* After packet filtering, change source only for VS/NAT */
@@ -2224,7 +2215,7 @@ static const struct nf_hook_ops ip_vs_ops6[] = {
 	/* After packet filtering (but before ip_vs_out_icmp), catch icmp
 	 * destined for 0.0.0.0/0, which is for incoming IPVS connections */
 	{
-		.hook		= ip_vs_forward_icmp_v6,
+		.hook		= ip_vs_forward_icmp,
 		.pf		= NFPROTO_IPV6,
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= 99,