net/netfilter/nf_conntrack_ecache.c

   1 /* Event cache for netfilter. */
   2
   3 /*
   4  * (C) 2005 Harald Welte <laforge@gnumonks.org>
   5  * (C) 2005 Patrick McHardy <kaber@trash.net>
   6  * (C) 2005-2006 Netfilter Core Team <coreteam@netfilter.org>
   7  * (C) 2005 USAGI/WIDE Project <http://www.linux-ipv6.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/types.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/stddef.h>
  19 #include <linux/err.h>
  20 #include <linux/percpu.h>
  21 #include <linux/kernel.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/slab.h>
  24 #include <linux/export.h>
  25
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_core.h>
  28 #include <net/netfilter/nf_conntrack_extend.h>
  29
  30 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  31
  32 #define ECACHE_RETRY_WAIT (HZ/10)
  33
  34 enum retry_state {
  35         STATE_CONGESTED,
  36         STATE_RESTART,
  37         STATE_DONE,
  38 };
  39
  40 static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
  41 {
  42         struct nf_conn *refs[16];
  43         struct nf_conntrack_tuple_hash *h;
  44         struct hlist_nulls_node *n;
  45         unsigned int evicted = 0;
  46         enum retry_state ret = STATE_DONE;
  47
  48         spin_lock(&pcpu->lock);
  49
  50         hlist_nulls_for_each_entry(h, n, &pcpu->dying, hnnode) {
  51                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
  52
  53                 if (nf_ct_is_dying(ct))
  54                         continue;
  55
  56                 if (nf_conntrack_event(IPCT_DESTROY, ct)) {
  57                         ret = STATE_CONGESTED;
  58                         break;
  59                 }
  60
  61                 /* we've got the event delivered, now it's dying */
  62                 set_bit(IPS_DYING_BIT, &ct->status);
  63                 refs[evicted] = ct;
  64
  65                 if (++evicted >= ARRAY_SIZE(refs)) {
  66                         ret = STATE_RESTART;
  67                         break;
  68                 }
  69         }
  70
  71         spin_unlock(&pcpu->lock);
  72
  73         /* can't _put while holding lock */
  74         while (evicted)
  75                 nf_ct_put(refs[--evicted]);
  76
  77         return ret;
  78 }
  79
  80 static void ecache_work(struct work_struct *work)
  81 {
  82         struct netns_ct *ctnet =
  83                 container_of(work, struct netns_ct, ecache_dwork.work);
  84         int cpu, delay = -1;
  85         struct ct_pcpu *pcpu;
  86
  87         local_bh_disable();
  88
  89         for_each_possible_cpu(cpu) {
  90                 enum retry_state ret;
  91
  92                 pcpu = per_cpu_ptr(ctnet->pcpu_lists, cpu);
  93
  94                 ret = ecache_work_evict_list(pcpu);
  95
  96                 switch (ret) {
  97                 case STATE_CONGESTED:
  98                         delay = ECACHE_RETRY_WAIT;
  99                         goto out;
 100                 case STATE_RESTART:
 101                         delay = 0;
 102                         break;
 103                 case STATE_DONE:
 104                         break;
 105                 }
 106         }
 107
 108  out:
 109         local_bh_enable();
 110
 111         ctnet->ecache_dwork_pending = delay > 0;
 112         if (delay >= 0)
 113                 schedule_delayed_work(&ctnet->ecache_dwork, delay);
 114 }
 115
 116 /* deliver cached events and clear cache entry - must be called with locally
 117  * disabled softirqs */
 118 void nf_ct_deliver_cached_events(struct nf_conn *ct)
 119 {
 120         struct net *net = nf_ct_net(ct);
 121         unsigned long events, missed;
 122         struct nf_ct_event_notifier *notify;
 123         struct nf_conntrack_ecache *e;
 124         struct nf_ct_event item;
 125         int ret;
 126
 127         rcu_read_lock();
 128         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
 129         if (notify == NULL)
 130                 goto out_unlock;
 131
 132         e = nf_ct_ecache_find(ct);
 133         if (e == NULL)
 134                 goto out_unlock;
 135
 136         events = xchg(&e->cache, 0);
 137
 138         if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events)
 139                 goto out_unlock;
 140
 141         /* We make a copy of the missed event cache without taking
 142          * the lock, thus we may send missed events twice. However,
 143          * this does not harm and it happens very rarely. */
 144         missed = e->missed;
 145
 146         if (!((events | missed) & e->ctmask))
 147                 goto out_unlock;
 148
 149         item.ct = ct;
 150         item.portid = 0;
 151         item.report = 0;
 152
 153         ret = notify->fcn(events | missed, &item);
 154
 155         if (likely(ret >= 0 && !missed))
 156                 goto out_unlock;
 157
 158         spin_lock_bh(&ct->lock);
 159         if (ret < 0)
 160                 e->missed |= events;
 161         else
 162                 e->missed &= ~missed;
 163         spin_unlock_bh(&ct->lock);
 164
 165 out_unlock:
 166         rcu_read_unlock();
 167 }
 168 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
 169
 170 int nf_conntrack_register_notifier(struct net *net,
 171                                    struct nf_ct_event_notifier *new)
 172 {
 173         int ret;
 174         struct nf_ct_event_notifier *notify;
 175
 176         mutex_lock(&nf_ct_ecache_mutex);
 177         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 178                                            lockdep_is_held(&nf_ct_ecache_mutex));
 179         if (notify != NULL) {
 180                 ret = -EBUSY;
 181                 goto out_unlock;
 182         }
 183         rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
 184         ret = 0;
 185
 186 out_unlock:
 187         mutex_unlock(&nf_ct_ecache_mutex);
 188         return ret;
 189 }
 190 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 191
 192 void nf_conntrack_unregister_notifier(struct net *net,
 193                                       struct nf_ct_event_notifier *new)
 194 {
 195         struct nf_ct_event_notifier *notify;
 196
 197         mutex_lock(&nf_ct_ecache_mutex);
 198         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 199                                            lockdep_is_held(&nf_ct_ecache_mutex));
 200         BUG_ON(notify != new);
 201         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 202         mutex_unlock(&nf_ct_ecache_mutex);
 203         /* synchronize_rcu() is called from ctnetlink_exit. */
 204 }
 205 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 206
 207 int nf_ct_expect_register_notifier(struct net *net,
 208                                    struct nf_exp_event_notifier *new)
 209 {
 210         int ret;
 211         struct nf_exp_event_notifier *notify;
 212
 213         mutex_lock(&nf_ct_ecache_mutex);
 214         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 215                                            lockdep_is_held(&nf_ct_ecache_mutex));
 216         if (notify != NULL) {
 217                 ret = -EBUSY;
 218                 goto out_unlock;
 219         }
 220         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
 221         ret = 0;
 222
 223 out_unlock:
 224         mutex_unlock(&nf_ct_ecache_mutex);
 225         return ret;
 226 }
 227 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 228
 229 void nf_ct_expect_unregister_notifier(struct net *net,
 230                                       struct nf_exp_event_notifier *new)
 231 {
 232         struct nf_exp_event_notifier *notify;
 233
 234         mutex_lock(&nf_ct_ecache_mutex);
 235         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 236                                            lockdep_is_held(&nf_ct_ecache_mutex));
 237         BUG_ON(notify != new);
 238         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
 239         mutex_unlock(&nf_ct_ecache_mutex);
 240         /* synchronize_rcu() is called from ctnetlink_exit. */
 241 }
 242 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 243
 244 #define NF_CT_EVENTS_DEFAULT 1
 245 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 246
 247 #ifdef CONFIG_SYSCTL
 248 static struct ctl_table event_sysctl_table[] = {
 249         {
 250                 .procname       = "nf_conntrack_events",
 251                 .data           = &init_net.ct.sysctl_events,
 252                 .maxlen         = sizeof(unsigned int),
 253                 .mode           = 0644,
 254                 .proc_handler   = proc_dointvec,
 255         },
 256         {}
 257 };
 258 #endif /* CONFIG_SYSCTL */
 259
 260 static struct nf_ct_ext_type event_extend __read_mostly = {
 261         .len    = sizeof(struct nf_conntrack_ecache),
 262         .align  = __alignof__(struct nf_conntrack_ecache),
 263         .id     = NF_CT_EXT_ECACHE,
 264 };
 265
 266 #ifdef CONFIG_SYSCTL
 267 static int nf_conntrack_event_init_sysctl(struct net *net)
 268 {
 269         struct ctl_table *table;
 270
 271         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 272                         GFP_KERNEL);
 273         if (!table)
 274                 goto out;
 275
 276         table[0].data = &net->ct.sysctl_events;
 277
 278         /* Don't export sysctls to unprivileged users */
 279         if (net->user_ns != &init_user_ns)
 280                 table[0].procname = NULL;
 281
 282         net->ct.event_sysctl_header =
 283                 register_net_sysctl(net, "net/netfilter", table);
 284         if (!net->ct.event_sysctl_header) {
 285                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 286                 goto out_register;
 287         }
 288         return 0;
 289
 290 out_register:
 291         kfree(table);
 292 out:
 293         return -ENOMEM;
 294 }
 295
 296 static void nf_conntrack_event_fini_sysctl(struct net *net)
 297 {
 298         struct ctl_table *table;
 299
 300         table = net->ct.event_sysctl_header->ctl_table_arg;
 301         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 302         kfree(table);
 303 }
 304 #else
 305 static int nf_conntrack_event_init_sysctl(struct net *net)
 306 {
 307         return 0;
 308 }
 309
 310 static void nf_conntrack_event_fini_sysctl(struct net *net)
 311 {
 312 }
 313 #endif /* CONFIG_SYSCTL */
 314
 315 int nf_conntrack_ecache_pernet_init(struct net *net)
 316 {
 317         net->ct.sysctl_events = nf_ct_events;
 318         INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work);
 319         return nf_conntrack_event_init_sysctl(net);
 320 }
 321
 322 void nf_conntrack_ecache_pernet_fini(struct net *net)
 323 {
 324         cancel_delayed_work_sync(&net->ct.ecache_dwork);
 325         nf_conntrack_event_fini_sysctl(net);
 326 }
 327
 328 int nf_conntrack_ecache_init(void)
 329 {
 330         int ret = nf_ct_extend_register(&event_extend);
 331         if (ret < 0)
 332                 pr_err("nf_ct_event: Unable to register event extension.\n");
 333         return ret;
 334 }
 335
 336 void nf_conntrack_ecache_fini(void)
 337 {
 338         nf_ct_extend_unregister(&event_extend);
 339 }