[PATCH?] Fix sniffing of ARP replies

[Petr Vandrovec <vandrove@xxxxxxxxxx>]

Hi Dave,
  after recent changes in packet_type interface I stopped setting
af_packet_priv - as you told that it is only for AF_PACKET, for nobody
else. And - things stopped working.

  After some debugging I found that there are skb's with ->sk == NULL -
namely ARP replies - and if af_packet_priv == NULL, these skbs are not
delivered to the registered ptype.

  Is change below correct, or should I simple set af_packet_priv to
non-NULL value, like I did before (and like I have to do it again for
older kernels, in the light of problems I'm seeing now)?
                                        Thanks,
                                                Petr Vandrovec


diff -urdN linux/net/core/dev.c linux/net/core/dev.c
--- linux/net/core/dev.c        2003-10-15 14:05:23.000000000 +0000
+++ linux/net/core/dev.c        2003-10-15 16:52:41.000000000 +0000
@@ -942,7 +942,8 @@
                 * they originated from - MvS (miquels@xxxxxxxxxxxxxx)
                 */
                if ((ptype->dev == dev || !ptype->dev) &&
-                   (struct sock *)ptype->af_packet_priv != skb->sk) {
+                   (ptype->af_packet_priv == NULL ||
+                    (struct sock *)ptype->af_packet_priv != skb->sk)) {
                        struct sk_buff *skb2= skb_clone(skb, GFP_ATOMIC);
                        if (!skb2)
                                break;