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                 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 */
  49 void 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 }
  60 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  61
  62 /* Deliver cached events for old pending events, if current conntrack != old */
  63 void __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 }
  77 EXPORT_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 */
  81 void 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
  93 int 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
 101 void nf_conntrack_ecache_fini(struct net *net)
 102 {
 103         free_percpu(net->ct.ecache);
 104 }
 105
 106 int nf_conntrack_register_notifier(struct notifier_block *nb)
 107 {
 108         return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
 109 }
 110 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 111
 112 int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 113 {
 114         return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 115 }
 116 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 117
 118 int nf_ct_expect_register_notifier(struct notifier_block *nb)
 119 {
 120         return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
 121 }
 122 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 123
 124 int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
 125 {
 126         return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
 127 }
 128 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);