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/kernel.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/slab.h>
  22
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_core.h>
  25 #include <net/netfilter/nf_conntrack_extend.h>
  26
  27 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  28
  29 struct nf_ct_event_notifier *nf_conntrack_event_cb __read_mostly;
  30 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
  31
  32 struct nf_exp_event_notifier *nf_expect_event_cb __read_mostly;
  33 EXPORT_SYMBOL_GPL(nf_expect_event_cb);
  34
  35 /* deliver cached events and clear cache entry - must be called with locally
  36  * disabled softirqs */
  37 void nf_ct_deliver_cached_events(struct nf_conn *ct)
  38 {
  39         unsigned long events;
  40         struct nf_ct_event_notifier *notify;
  41         struct nf_conntrack_ecache *e;
  42
  43         rcu_read_lock();
  44         notify = rcu_dereference(nf_conntrack_event_cb);
  45         if (notify == NULL)
  46                 goto out_unlock;
  47
  48         e = nf_ct_ecache_find(ct);
  49         if (e == NULL)
  50                 goto out_unlock;
  51
  52         events = xchg(&e->cache, 0);
  53
  54         if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct) && events) {
  55                 struct nf_ct_event item = {
  56                         .ct     = ct,
  57                         .pid    = 0,
  58                         .report = 0
  59                 };
  60                 int ret;
  61                 /* We make a copy of the missed event cache without taking
  62                  * the lock, thus we may send missed events twice. However,
  63                  * this does not harm and it happens very rarely. */
  64                 unsigned long missed = e->missed;
  65
  66                 ret = notify->fcn(events | missed, &item);
  67                 if (unlikely(ret < 0 || missed)) {
  68                         spin_lock_bh(&ct->lock);
  69                         if (ret < 0)
  70                                 e->missed |= events;
  71                         else
  72                                 e->missed &= ~missed;
  73                         spin_unlock_bh(&ct->lock);
  74                 }
  75         }
  76
  77 out_unlock:
  78         rcu_read_unlock();
  79 }
  80 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  81
  82 int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
  83 {
  84         int ret = 0;
  85         struct nf_ct_event_notifier *notify;
  86
  87         mutex_lock(&nf_ct_ecache_mutex);
  88         notify = rcu_dereference(nf_conntrack_event_cb);
  89         if (notify != NULL) {
  90                 ret = -EBUSY;
  91                 goto out_unlock;
  92         }
  93         rcu_assign_pointer(nf_conntrack_event_cb, new);
  94         mutex_unlock(&nf_ct_ecache_mutex);
  95         return ret;
  96
  97 out_unlock:
  98         mutex_unlock(&nf_ct_ecache_mutex);
  99         return ret;
 100 }
 101 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 102
 103 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 104 {
 105         struct nf_ct_event_notifier *notify;
 106
 107         mutex_lock(&nf_ct_ecache_mutex);
 108         notify = rcu_dereference(nf_conntrack_event_cb);
 109         BUG_ON(notify != new);
 110         rcu_assign_pointer(nf_conntrack_event_cb, NULL);
 111         mutex_unlock(&nf_ct_ecache_mutex);
 112 }
 113 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 114
 115 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 116 {
 117         int ret = 0;
 118         struct nf_exp_event_notifier *notify;
 119
 120         mutex_lock(&nf_ct_ecache_mutex);
 121         notify = rcu_dereference(nf_expect_event_cb);
 122         if (notify != NULL) {
 123                 ret = -EBUSY;
 124                 goto out_unlock;
 125         }
 126         rcu_assign_pointer(nf_expect_event_cb, new);
 127         mutex_unlock(&nf_ct_ecache_mutex);
 128         return ret;
 129
 130 out_unlock:
 131         mutex_unlock(&nf_ct_ecache_mutex);
 132         return ret;
 133 }
 134 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 135
 136 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 137 {
 138         struct nf_exp_event_notifier *notify;
 139
 140         mutex_lock(&nf_ct_ecache_mutex);
 141         notify = rcu_dereference(nf_expect_event_cb);
 142         BUG_ON(notify != new);
 143         rcu_assign_pointer(nf_expect_event_cb, NULL);
 144         mutex_unlock(&nf_ct_ecache_mutex);
 145 }
 146 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 147
 148 #define NF_CT_EVENTS_DEFAULT 1
 149 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 150 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 151
 152 #ifdef CONFIG_SYSCTL
 153 static struct ctl_table event_sysctl_table[] = {
 154         {
 155                 .procname       = "nf_conntrack_events",
 156                 .data           = &init_net.ct.sysctl_events,
 157                 .maxlen         = sizeof(unsigned int),
 158                 .mode           = 0644,
 159                 .proc_handler   = proc_dointvec,
 160         },
 161         {
 162                 .procname       = "nf_conntrack_events_retry_timeout",
 163                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 164                 .maxlen         = sizeof(unsigned int),
 165                 .mode           = 0644,
 166                 .proc_handler   = proc_dointvec_jiffies,
 167         },
 168         {}
 169 };
 170 #endif /* CONFIG_SYSCTL */
 171
 172 static struct nf_ct_ext_type event_extend __read_mostly = {
 173         .len    = sizeof(struct nf_conntrack_ecache),
 174         .align  = __alignof__(struct nf_conntrack_ecache),
 175         .id     = NF_CT_EXT_ECACHE,
 176 };
 177
 178 #ifdef CONFIG_SYSCTL
 179 static int nf_conntrack_event_init_sysctl(struct net *net)
 180 {
 181         struct ctl_table *table;
 182
 183         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 184                         GFP_KERNEL);
 185         if (!table)
 186                 goto out;
 187
 188         table[0].data = &net->ct.sysctl_events;
 189         table[1].data = &net->ct.sysctl_events_retry_timeout;
 190
 191         net->ct.event_sysctl_header =
 192                 register_net_sysctl_table(net,
 193                                           nf_net_netfilter_sysctl_path, table);
 194         if (!net->ct.event_sysctl_header) {
 195                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 196                 goto out_register;
 197         }
 198         return 0;
 199
 200 out_register:
 201         kfree(table);
 202 out:
 203         return -ENOMEM;
 204 }
 205
 206 static void nf_conntrack_event_fini_sysctl(struct net *net)
 207 {
 208         struct ctl_table *table;
 209
 210         table = net->ct.event_sysctl_header->ctl_table_arg;
 211         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 212         kfree(table);
 213 }
 214 #else
 215 static int nf_conntrack_event_init_sysctl(struct net *net)
 216 {
 217         return 0;
 218 }
 219
 220 static void nf_conntrack_event_fini_sysctl(struct net *net)
 221 {
 222 }
 223 #endif /* CONFIG_SYSCTL */
 224
 225 int nf_conntrack_ecache_init(struct net *net)
 226 {
 227         int ret;
 228
 229         net->ct.sysctl_events = nf_ct_events;
 230         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 231
 232         if (net_eq(net, &init_net)) {
 233                 ret = nf_ct_extend_register(&event_extend);
 234                 if (ret < 0) {
 235                         printk(KERN_ERR "nf_ct_event: Unable to register "
 236                                         "event extension.\n");
 237                         goto out_extend_register;
 238                 }
 239         }
 240
 241         ret = nf_conntrack_event_init_sysctl(net);
 242         if (ret < 0)
 243                 goto out_sysctl;
 244
 245         return 0;
 246
 247 out_sysctl:
 248         if (net_eq(net, &init_net))
 249                 nf_ct_extend_unregister(&event_extend);
 250 out_extend_register:
 251         return ret;
 252 }
 253
 254 void nf_conntrack_ecache_fini(struct net *net)
 255 {
 256         nf_conntrack_event_fini_sysctl(net);
 257         if (net_eq(net, &init_net))
 258                 nf_ct_extend_unregister(&event_extend);
 259 }