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_protected(nf_conntrack_event_cb,
  89                                            lockdep_is_held(&nf_ct_ecache_mutex));
  90         if (notify != NULL) {
  91                 ret = -EBUSY;
  92                 goto out_unlock;
  93         }
  94         rcu_assign_pointer(nf_conntrack_event_cb, new);
  95         mutex_unlock(&nf_ct_ecache_mutex);
  96         return ret;
  97
  98 out_unlock:
  99         mutex_unlock(&nf_ct_ecache_mutex);
 100         return ret;
 101 }
 102 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 103
 104 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 105 {
 106         struct nf_ct_event_notifier *notify;
 107
 108         mutex_lock(&nf_ct_ecache_mutex);
 109         notify = rcu_dereference_protected(nf_conntrack_event_cb,
 110                                            lockdep_is_held(&nf_ct_ecache_mutex));
 111         BUG_ON(notify != new);
 112         rcu_assign_pointer(nf_conntrack_event_cb, NULL);
 113         mutex_unlock(&nf_ct_ecache_mutex);
 114 }
 115 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 116
 117 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 118 {
 119         int ret = 0;
 120         struct nf_exp_event_notifier *notify;
 121
 122         mutex_lock(&nf_ct_ecache_mutex);
 123         notify = rcu_dereference_protected(nf_expect_event_cb,
 124                                            lockdep_is_held(&nf_ct_ecache_mutex));
 125         if (notify != NULL) {
 126                 ret = -EBUSY;
 127                 goto out_unlock;
 128         }
 129         rcu_assign_pointer(nf_expect_event_cb, new);
 130         mutex_unlock(&nf_ct_ecache_mutex);
 131         return ret;
 132
 133 out_unlock:
 134         mutex_unlock(&nf_ct_ecache_mutex);
 135         return ret;
 136 }
 137 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 138
 139 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 140 {
 141         struct nf_exp_event_notifier *notify;
 142
 143         mutex_lock(&nf_ct_ecache_mutex);
 144         notify = rcu_dereference_protected(nf_expect_event_cb,
 145                                            lockdep_is_held(&nf_ct_ecache_mutex));
 146         BUG_ON(notify != new);
 147         rcu_assign_pointer(nf_expect_event_cb, NULL);
 148         mutex_unlock(&nf_ct_ecache_mutex);
 149 }
 150 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 151
 152 #define NF_CT_EVENTS_DEFAULT 1
 153 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 154 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 155
 156 #ifdef CONFIG_SYSCTL
 157 static struct ctl_table event_sysctl_table[] = {
 158         {
 159                 .procname       = "nf_conntrack_events",
 160                 .data           = &init_net.ct.sysctl_events,
 161                 .maxlen         = sizeof(unsigned int),
 162                 .mode           = 0644,
 163                 .proc_handler   = proc_dointvec,
 164         },
 165         {
 166                 .procname       = "nf_conntrack_events_retry_timeout",
 167                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 168                 .maxlen         = sizeof(unsigned int),
 169                 .mode           = 0644,
 170                 .proc_handler   = proc_dointvec_jiffies,
 171         },
 172         {}
 173 };
 174 #endif /* CONFIG_SYSCTL */
 175
 176 static struct nf_ct_ext_type event_extend __read_mostly = {
 177         .len    = sizeof(struct nf_conntrack_ecache),
 178         .align  = __alignof__(struct nf_conntrack_ecache),
 179         .id     = NF_CT_EXT_ECACHE,
 180 };
 181
 182 #ifdef CONFIG_SYSCTL
 183 static int nf_conntrack_event_init_sysctl(struct net *net)
 184 {
 185         struct ctl_table *table;
 186
 187         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 188                         GFP_KERNEL);
 189         if (!table)
 190                 goto out;
 191
 192         table[0].data = &net->ct.sysctl_events;
 193         table[1].data = &net->ct.sysctl_events_retry_timeout;
 194
 195         net->ct.event_sysctl_header =
 196                 register_net_sysctl_table(net,
 197                                           nf_net_netfilter_sysctl_path, table);
 198         if (!net->ct.event_sysctl_header) {
 199                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 200                 goto out_register;
 201         }
 202         return 0;
 203
 204 out_register:
 205         kfree(table);
 206 out:
 207         return -ENOMEM;
 208 }
 209
 210 static void nf_conntrack_event_fini_sysctl(struct net *net)
 211 {
 212         struct ctl_table *table;
 213
 214         table = net->ct.event_sysctl_header->ctl_table_arg;
 215         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 216         kfree(table);
 217 }
 218 #else
 219 static int nf_conntrack_event_init_sysctl(struct net *net)
 220 {
 221         return 0;
 222 }
 223
 224 static void nf_conntrack_event_fini_sysctl(struct net *net)
 225 {
 226 }
 227 #endif /* CONFIG_SYSCTL */
 228
 229 int nf_conntrack_ecache_init(struct net *net)
 230 {
 231         int ret;
 232
 233         net->ct.sysctl_events = nf_ct_events;
 234         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 235
 236         if (net_eq(net, &init_net)) {
 237                 ret = nf_ct_extend_register(&event_extend);
 238                 if (ret < 0) {
 239                         printk(KERN_ERR "nf_ct_event: Unable to register "
 240                                         "event extension.\n");
 241                         goto out_extend_register;
 242                 }
 243         }
 244
 245         ret = nf_conntrack_event_init_sysctl(net);
 246         if (ret < 0)
 247                 goto out_sysctl;
 248
 249         return 0;
 250
 251 out_sysctl:
 252         if (net_eq(net, &init_net))
 253                 nf_ct_extend_unregister(&event_extend);
 254 out_extend_register:
 255         return ret;
 256 }
 257
 258 void nf_conntrack_ecache_fini(struct net *net)
 259 {
 260         nf_conntrack_event_fini_sysctl(net);
 261         if (net_eq(net, &init_net))
 262                 nf_ct_extend_unregister(&event_extend);
 263 }