ipv6: Add an error handler for icmp6

pmtu and redirect events are now handled in the protocols error handler,
so add an error handler for icmp6 to do this. It is needed in the case
when we have no socket context. Based on a patch by Duan Jiong.
Reported-by: NDuan Jiong <djduanjiong@gmail.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/icmp.c

@@ -81,10 +81,22 @@ static inline struct sock *icmpv6_sk(struct net *net)
 	return net->ipv6.icmp_sk[smp_processor_id()];
 }
 
+static void icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		       u8 type, u8 code, int offset, __be32 info)
+{
+	struct net *net = dev_net(skb->dev);
+
+	if (type == ICMPV6_PKT_TOOBIG)
+		ip6_update_pmtu(skb, net, info, 0, 0);
+	else if (type == NDISC_REDIRECT)
+		ip6_redirect(skb, net, 0, 0);
+}
+
 static int icmpv6_rcv(struct sk_buff *skb);
 
 static const struct inet6_protocol icmpv6_protocol = {
 	.handler	=	icmpv6_rcv,
+	.err_handler	=	icmpv6_err,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 };