: Drop conntrack reference when packet leaves IP

We had reoccuring problems with hanging conntrack module unload because not all references could be reclaimed. Some were caused by real leaks and were fixed, but queued packets are still a problem. A packet with a conntrack reference can be held infinte time in qdiscs or AF_PACKET socket receive queues. This patch drops the conntrack reference when the packet leaves IP, so we don't have to make assumptions about its fate.

# This is a BitKeeper generated diff -Nru style patch. #
# ChangeSet
# 2005/03/28 22:23:34+02:00 [email protected]
# [NETFILTER]: Drop conntrack reference when packet leaves IP
#

#   In the event a raw socket is created for sending purposes only, the creator
#   never bothers to check the socket's receive queue.  But we continue to
#   add skbs to its queue until it fills up.
#   
#   Unfortunately, if ip_conntrack is loaded on the box, each skb we add to the
#   queue potentially holds a reference to a conntrack.  If the user attempts
#   to unload ip_conntrack, we will spin around forever since the queued skbs
#   are pinned.
#   
#   Signed-off-by: Patrick McHardy <[email protected]>
# 
# net/ipv4/netfilter/ip_conntrack_standalone.c
#   2005/03/28 22:23:25+02:00 [email protected] +0 -7
#   [NETFILTER]: Drop conntrack reference when packet leaves IP
#   
#   In the event a raw socket is created for sending purposes only, the creator
#   never bothers to check the socket's receive queue.  But we continue to
#   add skbs to its queue until it fills up.
#   
#   Unfortunately, if ip_conntrack is loaded on the box, each skb we add to the
#   queue potentially holds a reference to a conntrack.  If the user attempts
#   to unload ip_conntrack, we will spin around forever since the queued skbs
#   are pinned.
#   
#   Signed-off-by: Patrick McHardy <[email protected]>
# 
# net/ipv4/ip_output.c
#   2005/03/28 22:23:25+02:00 [email protected] +2 -0
#   [NETFILTER]: Drop conntrack reference when packet leaves IP
#   
#   In the event a raw socket is created for sending purposes only, the creator
#   never bothers to check the socket's receive queue.  But we continue to
#   add skbs to its queue until it fills up.
#   
#   Unfortunately, if ip_conntrack is loaded on the box, each skb we add to the
#   queue potentially holds a reference to a conntrack.  If the user attempts
#   to unload ip_conntrack, we will spin around forever since the queued skbs
#   are pinned.
#   
#   Signed-off-by: Patrick McHardy <[email protected]>
# 
diff -Nru a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
--- a/net/ipv4/ip_output.c	2005-04-18 04:00:03 +02:00
+++ b/net/ipv4/ip_output.c	2005-04-18 04:00:03 +02:00
@@ -195,6 +195,8 @@
 	nf_debug_ip_finish_output2(skb);
 #endif /*CONFIG_NETFILTER_DEBUG*/

+ nf_reset(skb);
+
if (hh) {
int hh_alen;

diff -Nru a/net/ipv4/netfilter/ip_conntrack_standalone.c b/net/ipv4/netfilter/ip_conntrack_standalone.c
@@ -423,13 +423,6 @@
 				        const struct net_device *out,
 				        int (*okfn)(struct sk_buff *))
 {
-#if !defined(CONFIG_IP_NF_NAT) && !defined(CONFIG_IP_NF_NAT_MODULE)
-	/* Previously seen (loopback)?  Ignore.  Do this before
-           fragment check. */
-	if ((*pskb)->nfct)
-		return NF_ACCEPT;
-#endif
-
 	/* Gather fragments. */
 	if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
 		*pskb = ip_ct_gather_frags(*pskb,