From 381601e5bbae78d7c18d946fe874a63957edea13 Mon Sep 17 00:00:00 2001 From: Anders Franzen Date: Wed, 24 Nov 2010 05:47:18 +0000 Subject: Make the ip6_tunnel reflect the true mtu. The ip6_tunnel always assumes it consumes 40 bytes (ip6 hdr) of the mtu of the underlaying device. So for a normal ethernet bearer, the mtu of the ip6_tunnel is 1460. However, when creating a tunnel the encap limit option is enabled by default, and it consumes 8 bytes more, so the true mtu shall be 1452. I dont really know if this breaks some statement in some RFC, so this is a request for comments. Signed-off-by: Anders Franzen Signed-off-by: David S. Miller --- net/ipv6/ip6_tunnel.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'net') diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 2a59610c2a58..70e891a20fb9 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -1175,6 +1175,8 @@ static void ip6_tnl_link_config(struct ip6_tnl *t) sizeof (struct ipv6hdr); dev->mtu = rt->rt6i_dev->mtu - sizeof (struct ipv6hdr); + if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) + dev->mtu-=8; if (dev->mtu < IPV6_MIN_MTU) dev->mtu = IPV6_MIN_MTU; @@ -1363,12 +1365,17 @@ static const struct net_device_ops ip6_tnl_netdev_ops = { static void ip6_tnl_dev_setup(struct net_device *dev) { + struct ip6_tnl *t; + dev->netdev_ops = &ip6_tnl_netdev_ops; dev->destructor = ip6_dev_free; dev->type = ARPHRD_TUNNEL6; dev->hard_header_len = LL_MAX_HEADER + sizeof (struct ipv6hdr); dev->mtu = ETH_DATA_LEN - sizeof (struct ipv6hdr); + t = netdev_priv(dev); + if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) + dev->mtu-=8; dev->flags |= IFF_NOARP; dev->addr_len = sizeof(struct in6_addr); dev->features |= NETIF_F_NETNS_LOCAL; -- cgit v1.2.1