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                struct nf_ct_event item = {
  40                        .ct     = ecache->ct,
  41                        .pid    = 0,
  42                        .report = 0
  43                };
  44
  45                atomic_notifier_call_chain(&nf_conntrack_chain,
  46                                           ecache->events,
  47                                           &item);
  48        }
  49
  50        ecache->events = 0;
  51        nf_ct_put(ecache->ct);
  52        ecache->ct = NULL;
  53}
  54
  55/* Deliver all cached events for a particular conntrack. This is called
  56 * by code prior to async packet handling for freeing the skb */
  57void nf_ct_deliver_cached_events(const struct nf_conn *ct)
  58{
  59        struct net *net = nf_ct_net(ct);
  60        struct nf_conntrack_ecache *ecache;
  61
  62        local_bh_disable();
  63        ecache = per_cpu_ptr(net->ct.ecache, raw_smp_processor_id());
  64        if (ecache->ct == ct)
  65                __nf_ct_deliver_cached_events(ecache);
  66        local_bh_enable();
  67}
  68EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  69
  70/* Deliver cached events for old pending events, if current conntrack != old */
  71void __nf_ct_event_cache_init(struct nf_conn *ct)
  72{
  73        struct net *net = nf_ct_net(ct);
  74        struct nf_conntrack_ecache *ecache;
  75
  76        /* take care of delivering potentially old events */
  77        ecache = per_cpu_ptr(net->ct.ecache, raw_smp_processor_id());
  78        BUG_ON(ecache->ct == ct);
  79        if (ecache->ct)
  80                __nf_ct_deliver_cached_events(ecache);
  81        /* initialize for this conntrack/packet */
  82        ecache->ct = ct;
  83        nf_conntrack_get(&ct->ct_general);
  84}
  85EXPORT_SYMBOL_GPL(__nf_ct_event_cache_init);
  86
  87/* flush the event cache - touches other CPU's data and must not be called
  88 * while packets are still passing through the code */
  89void nf_ct_event_cache_flush(struct net *net)
  90{
  91        struct nf_conntrack_ecache *ecache;
  92        int cpu;
  93
  94        for_each_possible_cpu(cpu) {
  95                ecache = per_cpu_ptr(net->ct.ecache, cpu);
  96                if (ecache->ct)
  97                        nf_ct_put(ecache->ct);
  98        }
  99}
 100
 101int nf_conntrack_ecache_init(struct net *net)
 102{
 103        net->ct.ecache = alloc_percpu(struct nf_conntrack_ecache);
 104        if (!net->ct.ecache)
 105                return -ENOMEM;
 106        return 0;
 107}
 108
 109void nf_conntrack_ecache_fini(struct net *net)
 110{
 111        free_percpu(net->ct.ecache);
 112}
 113
 114int nf_conntrack_register_notifier(struct notifier_block *nb)
 115{
 116        return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
 117}
 118EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 119
 120int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 121{
 122        return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 123}
 124EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 125
 126int nf_ct_expect_register_notifier(struct notifier_block *nb)
 127{
 128        return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
 129}
 130EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 131
 132int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
 133{
 134        return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
 135}
 136EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 137