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Commit 23a3647b authored by Pravin B Shelar's avatar Pravin B Shelar Committed by David S. Miller
Browse files

ip_tunnels: Use skb-len to PMTU check. 



In path mtu check, ip header total length works for gre device
but not for gre-tap device.  Use skb len which is consistent
for all tunneling types.  This is old bug in gre.
This also fixes mtu calculation bug introduced by
commit c5441932 (GRE: Refactor GRE tunneling code).

Reported-by: default avatarTimo Teras <timo.teras@iki.fi>
Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 784771e7

net/ipv4/ip_tunnel.c

+55 −44
Original line number Diff line number Diff line
@@ -472,6 +472,54 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb, 
}

EXPORT_SYMBOL_GPL(ip_tunnel_rcv);



static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,

			    struct rtable *rt, __be16 df)

{

	struct ip_tunnel *tunnel = netdev_priv(dev);

	int pkt_size = skb->len - tunnel->hlen;

	int mtu;



	if (df)

		mtu = dst_mtu(&rt->dst) - dev->hard_header_len

					- sizeof(struct iphdr) - tunnel->hlen;

	else

		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;



	if (skb_dst(skb))

		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);



	if (skb->protocol == htons(ETH_P_IP)) {

		if (!skb_is_gso(skb) &&

		    (df & htons(IP_DF)) && mtu < pkt_size) {

			memset(IPCB(skb), 0, sizeof(*IPCB(skb)));

			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));

			return -E2BIG;

		}

	}

#if IS_ENABLED(CONFIG_IPV6)

	else if (skb->protocol == htons(ETH_P_IPV6)) {

		struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);



		if (rt6 && mtu < dst_mtu(skb_dst(skb)) &&

			   mtu >= IPV6_MIN_MTU) {

			if ((tunnel->parms.iph.daddr &&

			    !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||

			    rt6->rt6i_dst.plen == 128) {

				rt6->rt6i_flags |= RTF_MODIFIED;

				dst_metric_set(skb_dst(skb), RTAX_MTU, mtu);

			}

		}



		if (!skb_is_gso(skb) && mtu >= IPV6_MIN_MTU &&

					mtu < pkt_size) {

			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);

			return -E2BIG;

		}

	}

#endif

	return 0;

}



void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,

		    const struct iphdr *tnl_params, const u8 protocol)

{
@@ -483,7 +531,6 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 
	struct rtable *rt;		/* Route to the other host */

	unsigned int max_headroom;	/* The extra header space needed */

	__be32 dst;

	int mtu;

	int err;



	inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
@@ -560,51 +607,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 
		dev->stats.collisions++;

		goto tx_error;

	}

	df = tnl_params->frag_off;



	if (df)

		mtu = dst_mtu(&rt->dst) - dev->hard_header_len

					- sizeof(struct iphdr);

	else

		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;



	if (skb_dst(skb))

		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);



	if (skb->protocol == htons(ETH_P_IP)) {

		df |= (inner_iph->frag_off&htons(IP_DF));



		if (!skb_is_gso(skb) &&

		    (inner_iph->frag_off&htons(IP_DF)) &&

		     mtu < ntohs(inner_iph->tot_len)) {

			memset(IPCB(skb), 0, sizeof(*IPCB(skb)));

			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));

	if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off)) {

		ip_rt_put(rt);

		goto tx_error;

	}

	}

#if IS_ENABLED(CONFIG_IPV6)

	else if (skb->protocol == htons(ETH_P_IPV6)) {

		struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);



		if (rt6 && mtu < dst_mtu(skb_dst(skb)) &&

		    mtu >= IPV6_MIN_MTU) {

			if ((tunnel->parms.iph.daddr &&

			    !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||

			    rt6->rt6i_dst.plen == 128) {

				rt6->rt6i_flags |= RTF_MODIFIED;

				dst_metric_set(skb_dst(skb), RTAX_MTU, mtu);

			}

		}



		if (!skb_is_gso(skb) && mtu >= IPV6_MIN_MTU &&

		    mtu < skb->len) {

			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);

			ip_rt_put(rt);

			goto tx_error;

		}

	}

#endif



	if (tunnel->net != dev_net(dev))

		skb_scrub_packet(skb);
@@ -631,6 +638,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 
			ttl = ip4_dst_hoplimit(&rt->dst);

	}



	df = tnl_params->frag_off;

	if (skb->protocol == htons(ETH_P_IP))

		df |= (inner_iph->frag_off&htons(IP_DF));



	max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)

			+ rt->dst.header_len;

	if (max_headroom > dev->needed_headroom) {