Commit 128bb975 authored by Alexey Kodanev's avatar Alexey Kodanev Committed by David S. Miller

ip6_gre: init dev->mtu and dev->hard_header_len correctly

Commit b05229f4 ("gre6: Cleanup GREv6 transmit path,
call common GRE functions") moved dev->mtu initialization
from ip6gre_tunnel_setup() to ip6gre_tunnel_init(), as a
result, the previously set values, before ndo_init(), are
reset in the following cases:

* rtnl_create_link() can update dev->mtu from IFLA_MTU

* ip6gre_tnl_link_config() is invoked before ndo_init() in
  netlink and ioctl setup, so ndo_init() can reset MTU
  adjustments with the lower device MTU as well, dev->mtu
  and dev->hard_header_len.

  Not applicable for ip6gretap because it has one more call
  to ip6gre_tnl_link_config(tunnel, 1) in ip6gre_tap_init().

Fix the first case by updating dev->mtu with 'tb[IFLA_MTU]'
parameter if a user sets it manually on a device creation,
and fix the second one by moving ip6gre_tnl_link_config()
call after register_netdevice().

Fixes: b05229f4 ("gre6: Cleanup GREv6 transmit path, call common GRE functions")
Fixes: db2ec95d ("ip6_gre: Fix MTU setting")
Signed-off-by: default avatarAlexey Kodanev <>
Signed-off-by: default avatarDavid S. Miller <>
parent ed604c5d
......@@ -337,11 +337,12 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
nt->dev = dev;
nt->net = dev_net(dev);
ip6gre_tnl_link_config(nt, 1);
if (register_netdevice(dev) < 0)
goto failed_free;
ip6gre_tnl_link_config(nt, 1);
/* Can use a lockless transmit, unless we generate output sequences */
if (!(nt->parms.o_flags & TUNNEL_SEQ))
dev->features |= NETIF_F_LLTX;
......@@ -1303,7 +1304,6 @@ static void ip6gre_netlink_parms(struct nlattr *data[],
static int ip6gre_tap_init(struct net_device *dev)
struct ip6_tnl *tunnel;
int ret;
ret = ip6gre_tunnel_init_common(dev);
......@@ -1312,10 +1312,6 @@ static int ip6gre_tap_init(struct net_device *dev)
dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
tunnel = netdev_priv(dev);
ip6gre_tnl_link_config(tunnel, 1);
return 0;
......@@ -1408,12 +1404,16 @@ static int ip6gre_newlink(struct net *src_net, struct net_device *dev,
nt->dev = dev;
nt->net = dev_net(dev);
ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);
err = register_netdevice(dev);
if (err)
goto out;
ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);
if (tb[IFLA_MTU])
ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU]));
ip6gre_tunnel_link(ign, nt);
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