[PATCH 3.10 51/86] ip6_gre: dont allow to remove the fb_tunnel_dev

Greg Kroah-Hartman
2014-05-29T04:52:07Z

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

[ Upstream commit 54d63f787b652755e66eb4dd8892ee6d3f5197fc ]

It's possible to remove the FB tunnel with the command 'ip link del ip6gre0' but
this is unsafe, the module always supposes that this device exists. For example,
ip6gre_tunnel_lookup() may use it unconditionally.

Let's add a rtnl handler for dellink, which will never remove the FB tunnel (we
let ip6gre_destroy_tunnels() do the job).

Introduced by commit c12b395a4664 ("gre: Support GRE over IPv6").

CC: Dmitry Kozlov <xeb@mail.ru>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/ip6_gre.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1549,6 +1549,15 @@ static int ip6gre_changelink(struct net_
return 0;
}

+static void ip6gre_dellink(struct net_device *dev, struct list_head *head)
+{
+ struct net *net = dev_net(dev);
+ struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
+
+ if (dev != ign->fb_tunnel_dev)
+ unregister_netdevice_queue(dev, head);
+}
+
static size_t ip6gre_get_size(const struct net_device *dev)
{
return
@@ -1626,6 +1635,7 @@ static struct rtnl_link_ops ip6gre_link_
.validate = ip6gre_tunnel_validate,
.newlink = ip6gre_newlink,
.changelink = ip6gre_changelink,
+ .dellink = ip6gre_dellink,
.get_size = ip6gre_get_size,
.fill_info = ip6gre_fill_info,
};