tunnels: fix netns vs proto registration ordering

Same stuff as in ip_gre patch: receive hook can be called before netns
setup is done, oopsing in net_generic().

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
	   u8 type, u8 code, int offset, __be32 info)
{
	int rel_msg = 0;
	u8 rel_type = type;
	u8 rel_code = code;
	__u32 rel_info = ntohl(info);
	int err;
	struct sk_buff *skb2;
	struct iphdr *eiph;
	struct flowi fl;
	struct rtable *rt;

	err = ip6_tnl_err(skb, IPPROTO_IPIP, opt, &rel_type, &rel_code,
			  &rel_msg, &rel_info, offset);
	if (err < 0)
		return err;

	if (rel_msg == 0)
		return 0;

	switch (rel_type) {
	case ICMPV6_DEST_UNREACH:
		if (rel_code != ICMPV6_ADDR_UNREACH)
			return 0;
		rel_type = ICMP_DEST_UNREACH;
		rel_code = ICMP_HOST_UNREACH;
		break;
	case ICMPV6_PKT_TOOBIG:
		if (rel_code != 0)
			return 0;
		rel_type = ICMP_DEST_UNREACH;
		rel_code = ICMP_FRAG_NEEDED;
		break;
	default:
		return 0;
	}

	if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
		return 0;

	skb2 = skb_clone(skb, GFP_ATOMIC);
	if (!skb2)
		return 0;

	skb_dst_drop(skb2);

	skb_pull(skb2, offset);
	skb_reset_network_header(skb2);
	eiph = ip_hdr(skb2);

	/* Try to guess incoming interface */
	memset(&fl, 0, sizeof(fl));
	fl.fl4_dst = eiph->saddr;
	fl.fl4_tos = RT_TOS(eiph->tos);
	fl.proto = IPPROTO_IPIP;
	if (ip_route_output_key(dev_net(skb->dev), &rt, &fl))
		goto out;

	skb2->dev = rt->u.dst.dev;

	/* route "incoming" packet */
	if (rt->rt_flags & RTCF_LOCAL) {
		ip_rt_put(rt);
		rt = NULL;
		fl.fl4_dst = eiph->daddr;
		fl.fl4_src = eiph->saddr;
		fl.fl4_tos = eiph->tos;
		if (ip_route_output_key(dev_net(skb->dev), &rt, &fl) ||
		    rt->u.dst.dev->type != ARPHRD_TUNNEL) {
			ip_rt_put(rt);
			goto out;
		}
		skb_dst_set(skb2, (struct dst_entry *)rt);
	} else {
		ip_rt_put(rt);
		if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos,
				   skb2->dev) ||
		    skb_dst(skb2)->dev->type != ARPHRD_TUNNEL)
			goto out;
	}

	/* change mtu on this route */
	if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) {
		if (rel_info > dst_mtu(skb_dst(skb2)))
			goto out;

		skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), rel_info);
	}

	icmp_send(skb2, rel_type, rel_code, htonl(rel_info));

out:
	kfree_skb(skb2);
	return 0;
}

ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
	   u8 type, u8 code, int offset, __be32 info)
{
	int rel_msg = 0;
	u8 rel_type = type;
	u8 rel_code = code;
	__u32 rel_info = ntohl(info);
	int err;
	struct sk_buff *skb2;
	struct iphdr *eiph;
	struct flowi fl;
	struct rtable *rt;

	err = ip6_tnl_err(skb, IPPROTO_IPIP, opt, &rel_type, &rel_code,
			  &rel_msg, &rel_info, offset);
	if (err < 0)
		return err;

	if (rel_msg == 0)
		return 0;

	switch (rel_type) {
	case ICMPV6_DEST_UNREACH:
		if (rel_code != ICMPV6_ADDR_UNREACH)
			return 0;
		rel_type = ICMP_DEST_UNREACH;
		rel_code = ICMP_HOST_UNREACH;
		break;
	case ICMPV6_PKT_TOOBIG:
		if (rel_code != 0)
			return 0;
		rel_type = ICMP_DEST_UNREACH;
		rel_code = ICMP_FRAG_NEEDED;
		break;
	default:
		return 0;
	}

	if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
		return 0;

	skb2 = skb_clone(skb, GFP_ATOMIC);
	if (!skb2)
		return 0;

	skb_dst_drop(skb2);

	skb_pull(skb2, offset);
	skb_reset_network_header(skb2);
	eiph = ip_hdr(skb2);

	/* Try to guess incoming interface */
	memset(&fl, 0, sizeof(fl));
	fl.fl4_dst = eiph->saddr;
	fl.fl4_tos = RT_TOS(eiph->tos);
	fl.proto = IPPROTO_IPIP;
	if (ip_route_output_key(dev_net(skb->dev), &rt, &fl))
		goto out;

	skb2->dev = rt->u.dst.dev;

	/* route "incoming" packet */
	if (rt->rt_flags & RTCF_LOCAL) {
		ip_rt_put(rt);
		rt = NULL;
		fl.fl4_dst = eiph->daddr;
		fl.fl4_src = eiph->saddr;
		fl.fl4_tos = eiph->tos;
		if (ip_route_output_key(dev_net(skb->dev), &rt, &fl) ||
		    rt->u.dst.dev->type != ARPHRD_TUNNEL) {
			ip_rt_put(rt);
			goto out;
		}
		skb_dst_set(skb2, (struct dst_entry *)rt);
	} else {
		ip_rt_put(rt);
		if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos,
				   skb2->dev) ||
		    skb_dst(skb2)->dev->type != ARPHRD_TUNNEL)
			goto out;
	}

	/* change mtu on this route */
	if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) {
		if (rel_info > dst_mtu(skb_dst(skb2)))
			goto out;

		skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), rel_info);
	}

	icmp_send(skb2, rel_type, rel_code, htonl(rel_info));

out:
	kfree_skb(skb2);
	return 0;
}
