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

commit 38fe36a2 upstream.

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>
[Pablo Neira Ayuso: Backported to.3.0]
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/ipv4/netfilter/nf_nat_standalone.c

@@ -194,7 +194,8 @@ nf_nat_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)
 		   )
 			return ip_xfrm_me_harder(skb) == 0 ? ret : NF_DROP;
@@ -230,7 +231,8 @@ nf_nat_local_fn(unsigned int hooknum,
 				ret = NF_DROP;
 		}
 #ifdef CONFIG_XFRM
-		else if (ct->tuplehash[dir].tuple.dst.u.all !=
+		else if (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
+			 ct->tuplehash[dir].tuple.dst.u.all !=
 			 ct->tuplehash[!dir].tuple.src.u.all)
 			if (ip_xfrm_me_harder(skb))
 				ret = NF_DROP;