netfilter: nf_nat: don't check for port change on ICMP tuples

ICMP tuples have id in src and type/code in dst.
So comparing src.u.all with dst.u.all will always fail here
and ip_xfrm_me_harder() is called for every ICMP packet,
even if there was no NAT.
Signed-off-by: Ulrich Weber <ulrich.weber@sophos.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/iptable_nat.c

@@ -184,7 +184,8 @@ nf_nat_ipv4_out(unsigned int hooknum,
 
 		if ((ct->tuplehash[dir].tuple.src.u3.ip !=
 		     ct->tuplehash[!dir].tuple.dst.u3.ip) ||
-		    (ct->tuplehash[dir].tuple.src.u.all !=
+		    (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
+		     ct->tuplehash[dir].tuple.src.u.all !=
 		     ct->tuplehash[!dir].tuple.dst.u.all))
 			if (nf_xfrm_me_harder(skb, AF_INET) < 0)
 				ret = NF_DROP;
@@ -221,6 +222,7 @@ nf_nat_ipv4_local_fn(unsigned int hooknum,
 		}
 #ifdef CONFIG_XFRM
 		else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+			 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
 			 ct->tuplehash[dir].tuple.dst.u.all !=
 			 ct->tuplehash[!dir].tuple.src.u.all)
 			if (nf_xfrm_me_harder(skb, AF_INET) < 0)

net/ipv6/netfilter/ip6table_nat.c

@@ -186,7 +186,8 @@ nf_nat_ipv6_out(unsigned int hooknum,
 
 		if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
 				      &ct->tuplehash[!dir].tuple.dst.u3) ||
-		    (ct->tuplehash[dir].tuple.src.u.all !=
+		    (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
+		     ct->tuplehash[dir].tuple.src.u.all !=
 		     ct->tuplehash[!dir].tuple.dst.u.all))
 			if (nf_xfrm_me_harder(skb, AF_INET6) < 0)
 				ret = NF_DROP;
@@ -222,6 +223,7 @@ nf_nat_ipv6_local_fn(unsigned int hooknum,
 		}
 #ifdef CONFIG_XFRM
 		else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
+			 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
 			 ct->tuplehash[dir].tuple.dst.u.all !=
 			 ct->tuplehash[!dir].tuple.src.u.all)
 			if (nf_xfrm_me_harder(skb, AF_INET6))