1/* Event cache for netfilter. */
2
3/* (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/types.h>
13#include <linux/netfilter.h>
14#include <linux/skbuff.h>
15#include <linux/vmalloc.h>
16#include <linux/stddef.h>
17#include <linux/err.h>
18#include <linux/percpu.h>
19#include <linux/notifier.h>
20#include <linux/kernel.h>
21#include <linux/netdevice.h>
22
23#include <net/netfilter/nf_conntrack.h>
24#include <net/netfilter/nf_conntrack_core.h>
25
26ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain);
27EXPORT_SYMBOL_GPL(nf_conntrack_chain);
28
29ATOMIC_NOTIFIER_HEAD(nf_conntrack_expect_chain);
30EXPORT_SYMBOL_GPL(nf_conntrack_expect_chain);
31
32DEFINE_PER_CPU(struct nf_conntrack_ecache, nf_conntrack_ecache);
33EXPORT_PER_CPU_SYMBOL_GPL(nf_conntrack_ecache);
34
35/* deliver cached events and clear cache entry - must be called with locally
36 * disabled softirqs */
37static inline void
38__nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
39{
40	if (nf_ct_is_confirmed(ecache->ct) && !nf_ct_is_dying(ecache->ct)
41	    && ecache->events)
42		atomic_notifier_call_chain(&nf_conntrack_chain, ecache->events,
43				    ecache->ct);
44
45	ecache->events = 0;
46	nf_ct_put(ecache->ct);
47	ecache->ct = NULL;
48}
49
50/* Deliver all cached events for a particular conntrack. This is called
51 * by code prior to async packet handling for freeing the skb */
52void nf_ct_deliver_cached_events(const struct nf_conn *ct)
53{
54	struct nf_conntrack_ecache *ecache;
55
56	local_bh_disable();
57	ecache = &__get_cpu_var(nf_conntrack_ecache);
58	if (ecache->ct == ct)
59		__nf_ct_deliver_cached_events(ecache);
60	local_bh_enable();
61}
62EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
63
64/* Deliver cached events for old pending events, if current conntrack != old */
65void __nf_ct_event_cache_init(struct nf_conn *ct)
66{
67	struct nf_conntrack_ecache *ecache;
68
69	/* take care of delivering potentially old events */
70	ecache = &__get_cpu_var(nf_conntrack_ecache);
71	BUG_ON(ecache->ct == ct);
72	if (ecache->ct)
73		__nf_ct_deliver_cached_events(ecache);
74	/* initialize for this conntrack/packet */
75	ecache->ct = ct;
76	nf_conntrack_get(&ct->ct_general);
77}
78EXPORT_SYMBOL_GPL(__nf_ct_event_cache_init);
79
80/* flush the event cache - touches other CPU's data and must not be called
81 * while packets are still passing through the code */
82void nf_ct_event_cache_flush(void)
83{
84	struct nf_conntrack_ecache *ecache;
85	int cpu;
86
87	for_each_possible_cpu(cpu) {
88		ecache = &per_cpu(nf_conntrack_ecache, cpu);
89		if (ecache->ct)
90			nf_ct_put(ecache->ct);
91	}
92}
93
94int nf_conntrack_register_notifier(struct notifier_block *nb)
95{
96	return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
97}
98EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
99
100int nf_conntrack_unregister_notifier(struct notifier_block *nb)
101{
102	return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
103}
104EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
105
106int nf_conntrack_expect_register_notifier(struct notifier_block *nb)
107{
108	return atomic_notifier_chain_register(&nf_conntrack_expect_chain, nb);
109}
110EXPORT_SYMBOL_GPL(nf_conntrack_expect_register_notifier);
111
112int nf_conntrack_expect_unregister_notifier(struct notifier_block *nb)
113{
114	return atomic_notifier_chain_unregister(&nf_conntrack_expect_chain, nb);
115}
116EXPORT_SYMBOL_GPL(nf_conntrack_expect_unregister_notifier);
117