[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>

3 files changed, 12 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) +
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 97069399d864..41d8964591e7 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -382,6 +382,9 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
         struct iphdr *iph;
         u32 len;
 
+        if (dev->nd_net != &init_net)
+                goto drop;
+
         /* When the interface is in promisc. mode, drop all the crap
          * that it receives, do not try to analyse it.
          */
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 5ae4849878a3..08ff623371f0 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -426,6 +426,9 @@ ic_rarp_recv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
         unsigned char *sha, *tha;               /* s for "source", t for "target" */
         struct ic_device *d;
 
+        if (dev->nd_net != &init_net)
+                goto drop;
+
         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                 return NET_RX_DROP;
 
@@ -835,6 +838,9 @@ static int __init ic_bootp_recv(struct sk_buff *skb, struct net_device *dev, str
         struct ic_device *d;
         int len, ext_len;
 
+        if (dev->nd_net != &init_net)
+                goto drop;
+
         /* Perform verifications before taking the lock.  */
         if (skb->pkt_type == PACKET_OTHERHOST)
                 goto drop;