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ipv6: Allow the MTU of ipip6 tunnel to be set below 1280

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The (inner) MTU of a ipip6 (IPv4-in-IPv6) tunnel cannot be set below 1280, which is the minimum MTU in IPv6.
However, there should be no IPv6 on the tunnel interface at all, so the IPv6 rules should not apply.
More info at https://bugzilla.kernel.org/show_bug.cgi?id=15530

This patch allows to check the minimum MTU for ipv6 tunnel according to these rules:
-In case the tunnel is configured with ipip6 mode the minimum MTU is 68.
-In case the tunnel is configured with ip6ip6 or any mode the minimum MTU is 1280.

Signed-off-by: Oussama Ghorbel <ou.ghorbel@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Oussama Ghorbel 2013-10-03 14:49:26 +01:00 committed by David S. Miller
parent 3573540caf
commit 582442d6d5
1 changed files with 10 additions and 2 deletions
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12
net/ipv6/ip6_tunnel.c
View file

@ -1430,9 +1430,17 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
static int
ip6_tnl_change_mtu(struct net_device *dev, int new_mtu)
{
if (new_mtu < IPV6_MIN_MTU) {
return -EINVAL;
struct ip6_tnl *tnl = netdev_priv(dev);
if (tnl->parms.proto == IPPROTO_IPIP) {
if (new_mtu < 68)
return -EINVAL;
} else {
if (new_mtu < IPV6_MIN_MTU)
return -EINVAL;
}
if (new_mtu > 0xFFF8 - dev->hard_header_len)
return -EINVAL;
dev->mtu = new_mtu;
return 0;
}