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_l3proto.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_expect.h>
  27 #include <net/netfilter/nf_conntrack_helper.h>
  28 #include <net/netfilter/nf_conntrack_core.h>
  29
  30 ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain);
  31 EXPORT_SYMBOL_GPL(nf_conntrack_chain);
  32
  33 ATOMIC_NOTIFIER_HEAD(nf_conntrack_expect_chain);
  34 EXPORT_SYMBOL_GPL(nf_conntrack_expect_chain);
  35
  36 DEFINE_PER_CPU(struct nf_conntrack_ecache, nf_conntrack_ecache);
  37 EXPORT_PER_CPU_SYMBOL_GPL(nf_conntrack_ecache);
  38
  39 /* deliver cached events and clear cache entry - must be called with locally
  40  * disabled softirqs */
  41 static inline void
  42 __nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
  43 {
  44         if (nf_ct_is_confirmed(ecache->ct) && !nf_ct_is_dying(ecache->ct)
  45             && ecache->events)
  46                 atomic_notifier_call_chain(&nf_conntrack_chain, ecache->events,
  47                                     ecache->ct);
  48
  49         ecache->events = 0;
  50         nf_ct_put(ecache->ct);
  51         ecache->ct = NULL;
  52 }
  53
  54 /* Deliver all cached events for a particular conntrack. This is called
  55  * by code prior to async packet handling for freeing the skb */
  56 void nf_ct_deliver_cached_events(const struct nf_conn *ct)
  57 {
  58         struct nf_conntrack_ecache *ecache;
  59
  60         local_bh_disable();
  61         ecache = &__get_cpu_var(nf_conntrack_ecache);
  62         if (ecache->ct == ct)
  63                 __nf_ct_deliver_cached_events(ecache);
  64         local_bh_enable();
  65 }
  66 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  67
  68 /* Deliver cached events for old pending events, if current conntrack != old */
  69 void __nf_ct_event_cache_init(struct nf_conn *ct)
  70 {
  71         struct nf_conntrack_ecache *ecache;
  72
  73         /* take care of delivering potentially old events */
  74         ecache = &__get_cpu_var(nf_conntrack_ecache);
  75         BUG_ON(ecache->ct == ct);
  76         if (ecache->ct)
  77                 __nf_ct_deliver_cached_events(ecache);
  78         /* initialize for this conntrack/packet */
  79         ecache->ct = ct;
  80         nf_conntrack_get(&ct->ct_general);
  81 }
  82 EXPORT_SYMBOL_GPL(__nf_ct_event_cache_init);
  83
  84 /* flush the event cache - touches other CPU's data and must not be called
  85  * while packets are still passing through the code */
  86 void nf_ct_event_cache_flush(void)
  87 {
  88         struct nf_conntrack_ecache *ecache;
  89         int cpu;
  90
  91         for_each_possible_cpu(cpu) {
  92                 ecache = &per_cpu(nf_conntrack_ecache, cpu);
  93                 if (ecache->ct)
  94                         nf_ct_put(ecache->ct);
  95         }
  96 }
  97