Commit 8c91e162 authored Jul 11, 2013 by Alexander Duyck Committed by David S. Miller Jul 11, 2013

gre: Fix MTU sizing check for gretap tunnels



This change fixes an MTU sizing issue seen with gretap tunnels when non-gso
packets are sent from the interface.

In my case I was able to reproduce the issue by simply sending a ping of
1421 bytes with the gretap interface created on a device with a standard
1500 mtu.

This fix is based on the fact that the tunnel mtu is already adjusted by
dev->hard_header_len so it would make sense that any packets being compared
against that mtu should also be adjusted by hard_header_len and the tunnel
header instead of just the tunnel header.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Reported-by: Cong Wang <amwang@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 88d4f419

net/ipv4/ip_tunnel.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -476,7 +476,7 @@ 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 pkt_size = skb->len - tunnel->hlen - dev->hard_header_len;
		int mtu;

		if (df)

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