[NET]: Make packet reception network namespace safe

This patch modifies every packet receive function
registered with dev_add_pack() to drop packets if they
are not from the initial network namespace.

This should ensure that the various network stacks do
not receive packets in a anything but the initial network
namespace until the code has been converted and is ready
for them.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_3ad.c

@@ -29,6 +29,7 @@
 #include <linux/ethtool.h>
 #include <linux/if_bonding.h>
 #include <linux/pkt_sched.h>
+#include <net/net_namespace.h>
 #include "bonding.h"
 #include "bond_3ad.h"
 
@@ -2448,6 +2449,9 @@ int bond_3ad_lacpdu_recv(struct sk_buff *skb, struct net_device *dev, struct pac
 	struct slave *slave = NULL;
 	int ret = NET_RX_DROP;
 
+	if (dev->nd_net != &init_net)
+		goto out;
+
 	if (!(dev->flags & IFF_MASTER))
 		goto out;