[NETNS][IPV6] proc - protect snmp6 from non-init_net calls

This patchset avoids creation of the /proc entry for snmp6 when
the call is made from a network namespace different from the init_net.
Signed-off-by: NDaniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/proc.c

@@ -220,6 +220,9 @@ int snmp6_register_dev(struct inet6_dev *idev)
 	if (!idev || !idev->dev)
 		return -EINVAL;
 
+	if (idev->dev->nd_net != &init_net)
+		return 0;
+
 	if (!proc_net_devsnmp6)
 		return -ENOENT;