net/netfilter/nf_conntrack_ecache.c

   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
  26 ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain);
  27 EXPORT_SYMBOL_GPL(nf_conntrack_chain);
  28
  29 ATOMIC_NOTIFIER_HEAD(nf_ct_expect_chain);
  30 EXPORT_SYMBOL_GPL(nf_ct_expect_chain);
  31
  32 DEFINE_PER_CPU(struct nf_conntrack_ecache, nf_conntrack_ecache);
  33 EXPORT_PER_CPU_SYMBOL_GPL(nf_conntrack_ecache);
  34
  35 /* deliver cached events and clear cache entry - must be called with locally
  36  * disabled softirqs */
  37 static 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 */
  52 void 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 }
  62 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  63
  64 /* Deliver cached events for old pending events, if current conntrack != old */
  65 void __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 }
  78 EXPORT_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 */
  82 void 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
  94 int nf_conntrack_register_notifier(struct notifier_block *nb)
  95 {
  96         return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
  97 }
  98 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
  99
 100 int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 101 {
 102         return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 103 }
 104 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 105
 106 int nf_ct_expect_register_notifier(struct notifier_block *nb)
 107 {
 108         return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
 109 }
 110 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 111
 112 int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
 113 {
 114         return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
 115 }
 116 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);