[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/block/aoe/aoenet.c

@@ -8,6 +8,7 @@
 #include <linux/blkdev.h>
 #include <linux/netdevice.h>
 #include <linux/moduleparam.h>
+#include <net/net_namespace.h>
 #include <asm/unaligned.h>
 #include "aoe.h"
 
@@ -114,6 +115,9 @@ aoenet_rcv(struct sk_buff *skb, struct net_device *ifp, struct packet_type *pt,
 	struct aoe_hdr *h;
 	u32 n;
 
+	if (ifp->nd_net != &init_net)
+		goto exit;
+
 	skb = skb_share_check(skb, GFP_ATOMIC);
 	if (skb == NULL)
 		return 0;