ip6_tunnel: use the right netns in ioctl handler

Because the netdevice may be in another netns than the i/o netns, we should
use the i/o netns instead of dev_net(dev).
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ip6_tunnel.c

@@ -1340,8 +1340,8 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	int err = 0;
 	struct ip6_tnl_parm p;
 	struct __ip6_tnl_parm p1;
-	struct ip6_tnl *t = NULL;
-	struct net *net = dev_net(dev);
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct net *net = t->net;
 	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
 
 	switch (cmd) {
@@ -1353,11 +1353,11 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 			}
 			ip6_tnl_parm_from_user(&p1, &p);
 			t = ip6_tnl_locate(net, &p1, 0);
+			if (t == NULL)
+				t = netdev_priv(dev);
 		} else {
 			memset(&p, 0, sizeof(p));
 		}
-		if (t == NULL)
-			t = netdev_priv(dev);
 		ip6_tnl_parm_to_user(&p, &t->parms);
 		if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof (p))) {
 			err = -EFAULT;