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 /* deliver cached events and clear cache entry - must be called with locally
  33  * disabled softirqs */
  34 static 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 */
  57 void 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 }
  68 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  69
  70 /* Deliver cached events for old pending events, if current conntrack != old */
  71 void __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 }
  85 EXPORT_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 */
  89 void 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
 101 int 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
 109 void nf_conntrack_ecache_fini(struct net *net)
 110 {
 111         free_percpu(net->ct.ecache);
 112 }
 113
 114 int nf_conntrack_register_notifier(struct notifier_block *nb)
 115 {
 116         return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
 117 }
 118 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 119
 120 int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 121 {
 122         return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 123 }
 124 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 125
 126 int nf_ct_expect_register_notifier(struct notifier_block *nb)
 127 {
 128         return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
 129 }
 130 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 131
 132 int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
 133 {
 134         return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
 135 }
 136 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);