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

[deliverable/linux.git] / net / ipv6 / ip6_tunnel.c

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index a791552e042212d866b2cd96c35e2f0b5d289ab5..583b77e2f69be1d1499da479e2f8da1435d22a97 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -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;
 }