gre: Fix MTU sizing check for gretap tunnels
authorAlexander Duyck <alexander.h.duyck@intel.com>
Thu, 11 Jul 2013 20:12:22 +0000 (13:12 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 28 Jul 2013 23:30:02 +0000 (16:30 -0700)
commit6afbcb59964ec9dc3dd63ed96a9e2cda31f8a072
tree6aa13e211fe1cd87b341bab8069f1c69b7d92c81
parentf84ddbc58cfd8551757efe3c61242c4d6e9918ce
gre: Fix MTU sizing check for gretap tunnels

[ Upstream commit 8c91e162e058bb91b7766f26f4d5823a21941026 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/ipv4/ip_tunnel.c