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 #include <linux/export.h>
  23
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_core.h>
  26 #include <net/netfilter/nf_conntrack_extend.h>
  27
  28 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  29
  30 struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb __read_mostly;
  31 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
  32
  33 struct nf_exp_event_notifier __rcu *nf_expect_event_cb __read_mostly;
  34 EXPORT_SYMBOL_GPL(nf_expect_event_cb);
  35
  36 /* deliver cached events and clear cache entry - must be called with locally
  37  * disabled softirqs */
  38 void nf_ct_deliver_cached_events(struct nf_conn *ct)
  39 {
  40         unsigned long events;
  41         struct nf_ct_event_notifier *notify;
  42         struct nf_conntrack_ecache *e;
  43
  44         rcu_read_lock();
  45         notify = rcu_dereference(nf_conntrack_event_cb);
  46         if (notify == NULL)
  47                 goto out_unlock;
  48
  49         e = nf_ct_ecache_find(ct);
  50         if (e == NULL)
  51                 goto out_unlock;
  52
  53         events = xchg(&e->cache, 0);
  54
  55         if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct) && events) {
  56                 struct nf_ct_event item = {
  57                         .ct     = ct,
  58                         .pid    = 0,
  59                         .report = 0
  60                 };
  61                 int ret;
  62                 /* We make a copy of the missed event cache without taking
  63                  * the lock, thus we may send missed events twice. However,
  64                  * this does not harm and it happens very rarely. */
  65                 unsigned long missed = e->missed;
  66
  67                 if (!((events | missed) & e->ctmask))
  68                         goto out_unlock;
  69
  70                 ret = notify->fcn(events | missed, &item);
  71                 if (unlikely(ret < 0 || missed)) {
  72                         spin_lock_bh(&ct->lock);
  73                         if (ret < 0)
  74                                 e->missed |= events;
  75                         else
  76                                 e->missed &= ~missed;
  77                         spin_unlock_bh(&ct->lock);
  78                 }
  79         }
  80
  81 out_unlock:
  82         rcu_read_unlock();
  83 }
  84 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  85
  86 int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
  87 {
  88         int ret = 0;
  89         struct nf_ct_event_notifier *notify;
  90
  91         mutex_lock(&nf_ct_ecache_mutex);
  92         notify = rcu_dereference_protected(nf_conntrack_event_cb,
  93                                            lockdep_is_held(&nf_ct_ecache_mutex));
  94         if (notify != NULL) {
  95                 ret = -EBUSY;
  96                 goto out_unlock;
  97         }
  98         RCU_INIT_POINTER(nf_conntrack_event_cb, new);
  99         mutex_unlock(&nf_ct_ecache_mutex);
 100         return ret;
 101
 102 out_unlock:
 103         mutex_unlock(&nf_ct_ecache_mutex);
 104         return ret;
 105 }
 106 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 107
 108 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 109 {
 110         struct nf_ct_event_notifier *notify;
 111
 112         mutex_lock(&nf_ct_ecache_mutex);
 113         notify = rcu_dereference_protected(nf_conntrack_event_cb,
 114                                            lockdep_is_held(&nf_ct_ecache_mutex));
 115         BUG_ON(notify != new);
 116         RCU_INIT_POINTER(nf_conntrack_event_cb, NULL);
 117         mutex_unlock(&nf_ct_ecache_mutex);
 118 }
 119 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 120
 121 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 122 {
 123         int ret = 0;
 124         struct nf_exp_event_notifier *notify;
 125
 126         mutex_lock(&nf_ct_ecache_mutex);
 127         notify = rcu_dereference_protected(nf_expect_event_cb,
 128                                            lockdep_is_held(&nf_ct_ecache_mutex));
 129         if (notify != NULL) {
 130                 ret = -EBUSY;
 131                 goto out_unlock;
 132         }
 133         RCU_INIT_POINTER(nf_expect_event_cb, new);
 134         mutex_unlock(&nf_ct_ecache_mutex);
 135         return ret;
 136
 137 out_unlock:
 138         mutex_unlock(&nf_ct_ecache_mutex);
 139         return ret;
 140 }
 141 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 142
 143 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 144 {
 145         struct nf_exp_event_notifier *notify;
 146
 147         mutex_lock(&nf_ct_ecache_mutex);
 148         notify = rcu_dereference_protected(nf_expect_event_cb,
 149                                            lockdep_is_held(&nf_ct_ecache_mutex));
 150         BUG_ON(notify != new);
 151         RCU_INIT_POINTER(nf_expect_event_cb, NULL);
 152         mutex_unlock(&nf_ct_ecache_mutex);
 153 }
 154 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 155
 156 #define NF_CT_EVENTS_DEFAULT 1
 157 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 158 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 159
 160 #ifdef CONFIG_SYSCTL
 161 static struct ctl_table event_sysctl_table[] = {
 162         {
 163                 .procname       = "nf_conntrack_events",
 164                 .data           = &init_net.ct.sysctl_events,
 165                 .maxlen         = sizeof(unsigned int),
 166                 .mode           = 0644,
 167                 .proc_handler   = proc_dointvec,
 168         },
 169         {
 170                 .procname       = "nf_conntrack_events_retry_timeout",
 171                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 172                 .maxlen         = sizeof(unsigned int),
 173                 .mode           = 0644,
 174                 .proc_handler   = proc_dointvec_jiffies,
 175         },
 176         {}
 177 };
 178 #endif /* CONFIG_SYSCTL */
 179
 180 static struct nf_ct_ext_type event_extend __read_mostly = {
 181         .len    = sizeof(struct nf_conntrack_ecache),
 182         .align  = __alignof__(struct nf_conntrack_ecache),
 183         .id     = NF_CT_EXT_ECACHE,
 184 };
 185
 186 #ifdef CONFIG_SYSCTL
 187 static int nf_conntrack_event_init_sysctl(struct net *net)
 188 {
 189         struct ctl_table *table;
 190
 191         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 192                         GFP_KERNEL);
 193         if (!table)
 194                 goto out;
 195
 196         table[0].data = &net->ct.sysctl_events;
 197         table[1].data = &net->ct.sysctl_events_retry_timeout;
 198
 199         net->ct.event_sysctl_header =
 200                 register_net_sysctl_table(net,
 201                                           nf_net_netfilter_sysctl_path, table);
 202         if (!net->ct.event_sysctl_header) {
 203                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 204                 goto out_register;
 205         }
 206         return 0;
 207
 208 out_register:
 209         kfree(table);
 210 out:
 211         return -ENOMEM;
 212 }
 213
 214 static void nf_conntrack_event_fini_sysctl(struct net *net)
 215 {
 216         struct ctl_table *table;
 217
 218         table = net->ct.event_sysctl_header->ctl_table_arg;
 219         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 220         kfree(table);
 221 }
 222 #else
 223 static int nf_conntrack_event_init_sysctl(struct net *net)
 224 {
 225         return 0;
 226 }
 227
 228 static void nf_conntrack_event_fini_sysctl(struct net *net)
 229 {
 230 }
 231 #endif /* CONFIG_SYSCTL */
 232
 233 int nf_conntrack_ecache_init(struct net *net)
 234 {
 235         int ret;
 236
 237         net->ct.sysctl_events = nf_ct_events;
 238         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 239
 240         if (net_eq(net, &init_net)) {
 241                 ret = nf_ct_extend_register(&event_extend);
 242                 if (ret < 0) {
 243                         printk(KERN_ERR "nf_ct_event: Unable to register "
 244                                         "event extension.\n");
 245                         goto out_extend_register;
 246                 }
 247         }
 248
 249         ret = nf_conntrack_event_init_sysctl(net);
 250         if (ret < 0)
 251                 goto out_sysctl;
 252
 253         return 0;
 254
 255 out_sysctl:
 256         if (net_eq(net, &init_net))
 257                 nf_ct_extend_unregister(&event_extend);
 258 out_extend_register:
 259         return ret;
 260 }
 261
 262 void nf_conntrack_ecache_fini(struct net *net)
 263 {
 264         nf_conntrack_event_fini_sysctl(net);
 265         if (net_eq(net, &init_net))
 266                 nf_ct_extend_unregister(&event_extend);
 267 }