Commit 128bb975 authored Jan 18, 2018 by Alexey Kodanev Committed by David S. Miller Jan 18, 2018

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
  parameter.

* 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: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ed604c5d

net/ipv6/ip6_gre.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -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]));

		dev_hold(dev);
		ip6gre_tunnel_link(ign, nt);

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