[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>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 78dd3443016c..bde129708e22 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -932,6 +932,9 @@ static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
 {
         struct arphdr *arp;
 
+        if (dev->nd_net != &init_net)
+                goto freeskb;
+
         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
                                  (2 * dev->addr_len) +