linux/net/netfilter/nf_conntrack_ecache.c
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   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_ct_expect_chain);
  30EXPORT_SYMBOL_GPL(nf_ct_expect_chain);
  31
  32/* deliver cached events and clear cache entry - must be called with locally
  33 * disabled softirqs */
  34static inline void
  35__nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
  36{
  37        if (nf_ct_is_confirmed(ecache->ct) && !nf_ct_is_dying(ecache->ct)
  38            && ecache->events)
  39                atomic_notifier_call_chain(&nf_conntrack_chain, ecache->events,
  40                                    ecache->ct);
  41
  42        ecache->events = 0;
  43        nf_ct_put(ecache->ct);
  44        ecache->ct = NULL;
  45}
  46
  47/* Deliver all cached events for a particular conntrack. This is called
  48 * by code prior to async packet handling for freeing the skb */
  49void nf_ct_deliver_cached_events(const struct nf_conn *ct)
  50{
  51        struct net *net = nf_ct_net(ct);
  52        struct nf_conntrack_ecache *ecache;
  53
  54        local_bh_disable();
  55        ecache = per_cpu_ptr(net->ct.ecache, raw_smp_processor_id());
  56        if (ecache->ct == ct)
  57                __nf_ct_deliver_cached_events(ecache);
  58        local_bh_enable();
  59}
  60EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  61
  62/* Deliver cached events for old pending events, if current conntrack != old */
  63void __nf_ct_event_cache_init(struct nf_conn *ct)
  64{
  65        struct net *net = nf_ct_net(ct);
  66        struct nf_conntrack_ecache *ecache;
  67
  68        /* take care of delivering potentially old events */
  69        ecache = per_cpu_ptr(net->ct.ecache, raw_smp_processor_id());
  70        BUG_ON(ecache->ct == ct);
  71        if (ecache->ct)
  72                __nf_ct_deliver_cached_events(ecache);
  73        /* initialize for this conntrack/packet */
  74        ecache->ct = ct;
  75        nf_conntrack_get(&ct->ct_general);
  76}
  77EXPORT_SYMBOL_GPL(__nf_ct_event_cache_init);
  78
  79/* flush the event cache - touches other CPU's data and must not be called
  80 * while packets are still passing through the code */
  81void nf_ct_event_cache_flush(struct net *net)
  82{
  83        struct nf_conntrack_ecache *ecache;
  84        int cpu;
  85
  86        for_each_possible_cpu(cpu) {
  87                ecache = per_cpu_ptr(net->ct.ecache, cpu);
  88                if (ecache->ct)
  89                        nf_ct_put(ecache->ct);
  90        }
  91}
  92
  93int nf_conntrack_ecache_init(struct net *net)
  94{
  95        net->ct.ecache = alloc_percpu(struct nf_conntrack_ecache);
  96        if (!net->ct.ecache)
  97                return -ENOMEM;
  98        return 0;
  99}
 100
 101void nf_conntrack_ecache_fini(struct net *net)
 102{
 103        free_percpu(net->ct.ecache);
 104}
 105
 106int nf_conntrack_register_notifier(struct notifier_block *nb)
 107{
 108        return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
 109}
 110EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 111
 112int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 113{
 114        return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 115}
 116EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 117
 118int nf_ct_expect_register_notifier(struct notifier_block *nb)
 119{
 120        return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
 121}
 122EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 123
 124int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
 125{
 126        return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
 127}
 128EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 129