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 __rcu *nf_conntrack_event_cb __read_mostly;
  30 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
  31
  32 struct nf_exp_event_notifier __rcu *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                 if (!((events | missed) & e->ctmask))
  67                         goto out_unlock;
  68
  69                 ret = notify->fcn(events | missed, &item);
  70                 if (unlikely(ret < 0 || missed)) {
  71                         spin_lock_bh(&ct->lock);
  72                         if (ret < 0)
  73                                 e->missed |= events;
  74                         else
  75                                 e->missed &= ~missed;
  76                         spin_unlock_bh(&ct->lock);
  77                 }
  78         }
  79
  80 out_unlock:
  81         rcu_read_unlock();
  82 }
  83 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  84
  85 int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
  86 {
  87         int ret = 0;
  88         struct nf_ct_event_notifier *notify;
  89
  90         mutex_lock(&nf_ct_ecache_mutex);
  91         notify = rcu_dereference_protected(nf_conntrack_event_cb,
  92                                            lockdep_is_held(&nf_ct_ecache_mutex));
  93         if (notify != NULL) {
  94                 ret = -EBUSY;
  95                 goto out_unlock;
  96         }
  97         rcu_assign_pointer(nf_conntrack_event_cb, new);
  98         mutex_unlock(&nf_ct_ecache_mutex);
  99         return ret;
 100
 101 out_unlock:
 102         mutex_unlock(&nf_ct_ecache_mutex);
 103         return ret;
 104 }
 105 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 106
 107 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 108 {
 109         struct nf_ct_event_notifier *notify;
 110
 111         mutex_lock(&nf_ct_ecache_mutex);
 112         notify = rcu_dereference_protected(nf_conntrack_event_cb,
 113                                            lockdep_is_held(&nf_ct_ecache_mutex));
 114         BUG_ON(notify != new);
 115         rcu_assign_pointer(nf_conntrack_event_cb, NULL);
 116         mutex_unlock(&nf_ct_ecache_mutex);
 117 }
 118 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 119
 120 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 121 {
 122         int ret = 0;
 123         struct nf_exp_event_notifier *notify;
 124
 125         mutex_lock(&nf_ct_ecache_mutex);
 126         notify = rcu_dereference_protected(nf_expect_event_cb,
 127                                            lockdep_is_held(&nf_ct_ecache_mutex));
 128         if (notify != NULL) {
 129                 ret = -EBUSY;
 130                 goto out_unlock;
 131         }
 132         rcu_assign_pointer(nf_expect_event_cb, new);
 133         mutex_unlock(&nf_ct_ecache_mutex);
 134         return ret;
 135
 136 out_unlock:
 137         mutex_unlock(&nf_ct_ecache_mutex);
 138         return ret;
 139 }
 140 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 141
 142 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 143 {
 144         struct nf_exp_event_notifier *notify;
 145
 146         mutex_lock(&nf_ct_ecache_mutex);
 147         notify = rcu_dereference_protected(nf_expect_event_cb,
 148                                            lockdep_is_held(&nf_ct_ecache_mutex));
 149         BUG_ON(notify != new);
 150         rcu_assign_pointer(nf_expect_event_cb, NULL);
 151         mutex_unlock(&nf_ct_ecache_mutex);
 152 }
 153 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 154
 155 #define NF_CT_EVENTS_DEFAULT 1
 156 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 157 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 158
 159 #ifdef CONFIG_SYSCTL
 160 static struct ctl_table event_sysctl_table[] = {
 161         {
 162                 .procname       = "nf_conntrack_events",
 163                 .data           = &init_net.ct.sysctl_events,
 164                 .maxlen         = sizeof(unsigned int),
 165                 .mode           = 0644,
 166                 .proc_handler   = proc_dointvec,
 167         },
 168         {
 169                 .procname       = "nf_conntrack_events_retry_timeout",
 170                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 171                 .maxlen         = sizeof(unsigned int),
 172                 .mode           = 0644,
 173                 .proc_handler   = proc_dointvec_jiffies,
 174         },
 175         {}
 176 };
 177 #endif /* CONFIG_SYSCTL */
 178
 179 static struct nf_ct_ext_type event_extend __read_mostly = {
 180         .len    = sizeof(struct nf_conntrack_ecache),
 181         .align  = __alignof__(struct nf_conntrack_ecache),
 182         .id     = NF_CT_EXT_ECACHE,
 183 };
 184
 185 #ifdef CONFIG_SYSCTL
 186 static int nf_conntrack_event_init_sysctl(struct net *net)
 187 {
 188         struct ctl_table *table;
 189
 190         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 191                         GFP_KERNEL);
 192         if (!table)
 193                 goto out;
 194
 195         table[0].data = &net->ct.sysctl_events;
 196         table[1].data = &net->ct.sysctl_events_retry_timeout;
 197
 198         net->ct.event_sysctl_header =
 199                 register_net_sysctl_table(net,
 200                                           nf_net_netfilter_sysctl_path, table);
 201         if (!net->ct.event_sysctl_header) {
 202                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 203                 goto out_register;
 204         }
 205         return 0;
 206
 207 out_register:
 208         kfree(table);
 209 out:
 210         return -ENOMEM;
 211 }
 212
 213 static void nf_conntrack_event_fini_sysctl(struct net *net)
 214 {
 215         struct ctl_table *table;
 216
 217         table = net->ct.event_sysctl_header->ctl_table_arg;
 218         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 219         kfree(table);
 220 }
 221 #else
 222 static int nf_conntrack_event_init_sysctl(struct net *net)
 223 {
 224         return 0;
 225 }
 226
 227 static void nf_conntrack_event_fini_sysctl(struct net *net)
 228 {
 229 }
 230 #endif /* CONFIG_SYSCTL */
 231
 232 int nf_conntrack_ecache_init(struct net *net)
 233 {
 234         int ret;
 235
 236         net->ct.sysctl_events = nf_ct_events;
 237         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 238
 239         if (net_eq(net, &init_net)) {
 240                 ret = nf_ct_extend_register(&event_extend);
 241                 if (ret < 0) {
 242                         printk(KERN_ERR "nf_ct_event: Unable to register "
 243                                         "event extension.\n");
 244                         goto out_extend_register;
 245                 }
 246         }
 247
 248         ret = nf_conntrack_event_init_sysctl(net);
 249         if (ret < 0)
 250                 goto out_sysctl;
 251
 252         return 0;
 253
 254 out_sysctl:
 255         if (net_eq(net, &init_net))
 256                 nf_ct_extend_unregister(&event_extend);
 257 out_extend_register:
 258         return ret;
 259 }
 260
 261 void nf_conntrack_ecache_fini(struct net *net)
 262 {
 263         nf_conntrack_event_fini_sysctl(net);
 264         if (net_eq(net, &init_net))
 265                 nf_ct_extend_unregister(&event_extend);
 266 }