icmp: remove duplicate code

The same code which recognizes ICMP error packets is duplicated several
times. Use the icmp_is_err() and icmpv6_is_err() helpers instead, which
do the same thing.

ip_multipath_l3_keys() and tcf_nat_act() didn't check for all the error types,
assume that they should instead.

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/nf_socket_ipv4.c

@@ -31,16 +31,8 @@ extract_icmp4_fields(const struct sk_buff *skb, u8 *protocol,
 	if (icmph == NULL)
 		return 1;
 
-	switch (icmph->type) {
+	if (!icmp_is_err(icmph->type))
-	case ICMP_DEST_UNREACH:
-	case ICMP_SOURCE_QUENCH:
-	case ICMP_REDIRECT:
-	case ICMP_TIME_EXCEEDED:
-	case ICMP_PARAMETERPROB:
-		break;
-	default:
 		return 1;
-	}
 
 	inside_iph = skb_header_pointer(skb, outside_hdrlen +
 					sizeof(struct icmphdr),

net/ipv4/route.c

@@ -1894,10 +1894,7 @@ static void ip_multipath_l3_keys(const struct sk_buff *skb,
 	if (!icmph)
 		goto out;
 
-	if (icmph->type != ICMP_DEST_UNREACH &&
+	if (!icmp_is_err(icmph->type))
-	    icmph->type != ICMP_REDIRECT &&
-	    icmph->type != ICMP_TIME_EXCEEDED &&
-	    icmph->type != ICMP_PARAMETERPROB)
 		goto out;
 
 	inner_iph = skb_header_pointer(skb,

net/ipv6/route.c

@@ -2291,10 +2291,7 @@ static void ip6_multipath_l3_keys(const struct sk_buff *skb,
 	if (!icmph)
 		goto out;
 
-	if (icmph->icmp6_type != ICMPV6_DEST_UNREACH &&
+	if (!icmpv6_is_err(icmph->icmp6_type))
-	    icmph->icmp6_type != ICMPV6_PKT_TOOBIG &&
-	    icmph->icmp6_type != ICMPV6_TIME_EXCEED &&
-	    icmph->icmp6_type != ICMPV6_PARAMPROB)
 		goto out;
 
 	inner_iph = skb_header_pointer(skb,

net/netfilter/nf_conntrack_proto_icmp.c

@@ -235,11 +235,7 @@ int nf_conntrack_icmpv4_error(struct nf_conn *tmpl,
 	}
 
 	/* Need to track icmp error message? */
-	if (icmph->type != ICMP_DEST_UNREACH &&
+	if (!icmp_is_err(icmph->type))
-	    icmph->type != ICMP_SOURCE_QUENCH &&
-	    icmph->type != ICMP_TIME_EXCEEDED &&
-	    icmph->type != ICMP_PARAMETERPROB &&
-	    icmph->type != ICMP_REDIRECT)
 		return NF_ACCEPT;
 
 	memset(&outer_daddr, 0, sizeof(outer_daddr));

net/netfilter/xt_HMARK.c

@@ -239,11 +239,7 @@ static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff)
 		return 0;
 
 	/* Error message? */
-	if (icmph->type != ICMP_DEST_UNREACH &&
+	if (!icmp_is_err(icmph->type))
-	    icmph->type != ICMP_SOURCE_QUENCH &&
-	    icmph->type != ICMP_TIME_EXCEEDED &&
-	    icmph->type != ICMP_PARAMETERPROB &&
-	    icmph->type != ICMP_REDIRECT)
 		return 0;
 
 	*nhoff += iphsz + sizeof(_ih);

net/sched/act_nat.c

@@ -206,9 +206,7 @@ static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
 
 		icmph = (void *)(skb_network_header(skb) + ihl);
 
-		if ((icmph->type != ICMP_DEST_UNREACH) &&
+		if (!icmp_is_err(icmph->type))
-		    (icmph->type != ICMP_TIME_EXCEEDED) &&
-		    (icmph->type != ICMP_PARAMETERPROB))
 			break;
 
 		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +