[3.13.y.z extended stable] Patch "ip6_gre: don't allow to remove the fb_tunnel_dev" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ip6_gre: don't allow to remove the fb_tunnel_dev

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From d272fdcc16de9dd33c0651dd334ec69c649fbfbb Mon Sep 17 00:00:00 2001
From: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
Date: Mon, 14 Apr 2014 17:11:38 +0200
Subject: ip6_gre: don't allow to remove the fb_tunnel_dev

[ 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 at mail.ru>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/ipv6/ip6_gre.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 8acb286..01ee297 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1569,6 +1569,15 @@ static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],
 	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
@@ -1646,6 +1655,7 @@ static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
 	.validate	= ip6gre_tunnel_validate,
 	.newlink	= ip6gre_newlink,
 	.changelink	= ip6gre_changelink,
+	.dellink	= ip6gre_dellink,
 	.get_size	= ip6gre_get_size,
 	.fill_info	= ip6gre_fill_info,
 };
--
1.9.1