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 int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
 117                                   u32 portid, int report)
 118 {
 119         int ret = 0;
 120         struct net *net = nf_ct_net(ct);
 121         struct nf_ct_event_notifier *notify;
 122         struct nf_conntrack_ecache *e;
 123
 124         rcu_read_lock();
 125         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
 126         if (!notify)
 127                 goto out_unlock;
 128
 129         e = nf_ct_ecache_find(ct);
 130         if (!e)
 131                 goto out_unlock;
 132
 133         if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) {
 134                 struct nf_ct_event item = {
 135                         .ct     = ct,
 136                         .portid = e->portid ? e->portid : portid,
 137                         .report = report
 138                 };
 139                 /* This is a resent of a destroy event? If so, skip missed */
 140                 unsigned long missed = e->portid ? 0 : e->missed;
 141
 142                 if (!((eventmask | missed) & e->ctmask))
 143                         goto out_unlock;
 144
 145                 ret = notify->fcn(eventmask | missed, &item);
 146                 if (unlikely(ret < 0 || missed)) {
 147                         spin_lock_bh(&ct->lock);
 148                         if (ret < 0) {
 149                                 /* This is a destroy event that has been
 150                                  * triggered by a process, we store the PORTID
 151                                  * to include it in the retransmission.
 152                                  */
 153                                 if (eventmask & (1 << IPCT_DESTROY) &&
 154                                     e->portid == 0 && portid != 0)
 155                                         e->portid = portid;
 156                                 else
 157                                         e->missed |= eventmask;
 158                         } else {
 159                                 e->missed &= ~missed;
 160                         }
 161                         spin_unlock_bh(&ct->lock);
 162                 }
 163         }
 164 out_unlock:
 165         rcu_read_unlock();
 166         return ret;
 167 }
 168 EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
 169
 170 /* deliver cached events and clear cache entry - must be called with locally
 171  * disabled softirqs */
 172 void nf_ct_deliver_cached_events(struct nf_conn *ct)
 173 {
 174         struct net *net = nf_ct_net(ct);
 175         unsigned long events, missed;
 176         struct nf_ct_event_notifier *notify;
 177         struct nf_conntrack_ecache *e;
 178         struct nf_ct_event item;
 179         int ret;
 180
 181         rcu_read_lock();
 182         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
 183         if (notify == NULL)
 184                 goto out_unlock;
 185
 186         e = nf_ct_ecache_find(ct);
 187         if (e == NULL)
 188                 goto out_unlock;
 189
 190         events = xchg(&e->cache, 0);
 191
 192         if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events)
 193                 goto out_unlock;
 194
 195         /* We make a copy of the missed event cache without taking
 196          * the lock, thus we may send missed events twice. However,
 197          * this does not harm and it happens very rarely. */
 198         missed = e->missed;
 199
 200         if (!((events | missed) & e->ctmask))
 201                 goto out_unlock;
 202
 203         item.ct = ct;
 204         item.portid = 0;
 205         item.report = 0;
 206
 207         ret = notify->fcn(events | missed, &item);
 208
 209         if (likely(ret >= 0 && !missed))
 210                 goto out_unlock;
 211
 212         spin_lock_bh(&ct->lock);
 213         if (ret < 0)
 214                 e->missed |= events;
 215         else
 216                 e->missed &= ~missed;
 217         spin_unlock_bh(&ct->lock);
 218
 219 out_unlock:
 220         rcu_read_unlock();
 221 }
 222 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
 223
 224 void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
 225                                struct nf_conntrack_expect *exp,
 226                                u32 portid, int report)
 227
 228 {
 229         struct net *net = nf_ct_exp_net(exp);
 230         struct nf_exp_event_notifier *notify;
 231         struct nf_conntrack_ecache *e;
 232
 233         rcu_read_lock();
 234         notify = rcu_dereference(net->ct.nf_expect_event_cb);
 235         if (!notify)
 236                 goto out_unlock;
 237
 238         e = nf_ct_ecache_find(exp->master);
 239         if (!e)
 240                 goto out_unlock;
 241
 242         if (e->expmask & (1 << event)) {
 243                 struct nf_exp_event item = {
 244                         .exp    = exp,
 245                         .portid = portid,
 246                         .report = report
 247                 };
 248                 notify->fcn(1 << event, &item);
 249         }
 250 out_unlock:
 251         rcu_read_unlock();
 252 }
 253
 254 int nf_conntrack_register_notifier(struct net *net,
 255                                    struct nf_ct_event_notifier *new)
 256 {
 257         int ret;
 258         struct nf_ct_event_notifier *notify;
 259
 260         mutex_lock(&nf_ct_ecache_mutex);
 261         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 262                                            lockdep_is_held(&nf_ct_ecache_mutex));
 263         if (notify != NULL) {
 264                 ret = -EBUSY;
 265                 goto out_unlock;
 266         }
 267         rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
 268         ret = 0;
 269
 270 out_unlock:
 271         mutex_unlock(&nf_ct_ecache_mutex);
 272         return ret;
 273 }
 274 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 275
 276 void nf_conntrack_unregister_notifier(struct net *net,
 277                                       struct nf_ct_event_notifier *new)
 278 {
 279         struct nf_ct_event_notifier *notify;
 280
 281         mutex_lock(&nf_ct_ecache_mutex);
 282         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 283                                            lockdep_is_held(&nf_ct_ecache_mutex));
 284         BUG_ON(notify != new);
 285         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 286         mutex_unlock(&nf_ct_ecache_mutex);
 287 }
 288 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 289
 290 int nf_ct_expect_register_notifier(struct net *net,
 291                                    struct nf_exp_event_notifier *new)
 292 {
 293         int ret;
 294         struct nf_exp_event_notifier *notify;
 295
 296         mutex_lock(&nf_ct_ecache_mutex);
 297         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 298                                            lockdep_is_held(&nf_ct_ecache_mutex));
 299         if (notify != NULL) {
 300                 ret = -EBUSY;
 301                 goto out_unlock;
 302         }
 303         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
 304         ret = 0;
 305
 306 out_unlock:
 307         mutex_unlock(&nf_ct_ecache_mutex);
 308         return ret;
 309 }
 310 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 311
 312 void nf_ct_expect_unregister_notifier(struct net *net,
 313                                       struct nf_exp_event_notifier *new)
 314 {
 315         struct nf_exp_event_notifier *notify;
 316
 317         mutex_lock(&nf_ct_ecache_mutex);
 318         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 319                                            lockdep_is_held(&nf_ct_ecache_mutex));
 320         BUG_ON(notify != new);
 321         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
 322         mutex_unlock(&nf_ct_ecache_mutex);
 323 }
 324 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 325
 326 #define NF_CT_EVENTS_DEFAULT 1
 327 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 328
 329 #ifdef CONFIG_SYSCTL
 330 static struct ctl_table event_sysctl_table[] = {
 331         {
 332                 .procname       = "nf_conntrack_events",
 333                 .data           = &init_net.ct.sysctl_events,
 334                 .maxlen         = sizeof(unsigned int),
 335                 .mode           = 0644,
 336                 .proc_handler   = proc_dointvec,
 337         },
 338         {}
 339 };
 340 #endif /* CONFIG_SYSCTL */
 341
 342 static struct nf_ct_ext_type event_extend __read_mostly = {
 343         .len    = sizeof(struct nf_conntrack_ecache),
 344         .align  = __alignof__(struct nf_conntrack_ecache),
 345         .id     = NF_CT_EXT_ECACHE,
 346 };
 347
 348 #ifdef CONFIG_SYSCTL
 349 static int nf_conntrack_event_init_sysctl(struct net *net)
 350 {
 351         struct ctl_table *table;
 352
 353         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 354                         GFP_KERNEL);
 355         if (!table)
 356                 goto out;
 357
 358         table[0].data = &net->ct.sysctl_events;
 359
 360         /* Don't export sysctls to unprivileged users */
 361         if (net->user_ns != &init_user_ns)
 362                 table[0].procname = NULL;
 363
 364         net->ct.event_sysctl_header =
 365                 register_net_sysctl(net, "net/netfilter", table);
 366         if (!net->ct.event_sysctl_header) {
 367                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 368                 goto out_register;
 369         }
 370         return 0;
 371
 372 out_register:
 373         kfree(table);
 374 out:
 375         return -ENOMEM;
 376 }
 377
 378 static void nf_conntrack_event_fini_sysctl(struct net *net)
 379 {
 380         struct ctl_table *table;
 381
 382         table = net->ct.event_sysctl_header->ctl_table_arg;
 383         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 384         kfree(table);
 385 }
 386 #else
 387 static int nf_conntrack_event_init_sysctl(struct net *net)
 388 {
 389         return 0;
 390 }
 391
 392 static void nf_conntrack_event_fini_sysctl(struct net *net)
 393 {
 394 }
 395 #endif /* CONFIG_SYSCTL */
 396
 397 int nf_conntrack_ecache_pernet_init(struct net *net)
 398 {
 399         net->ct.sysctl_events = nf_ct_events;
 400         INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work);
 401         return nf_conntrack_event_init_sysctl(net);
 402 }
 403
 404 void nf_conntrack_ecache_pernet_fini(struct net *net)
 405 {
 406         cancel_delayed_work_sync(&net->ct.ecache_dwork);
 407         nf_conntrack_event_fini_sysctl(net);
 408 }
 409
 410 int nf_conntrack_ecache_init(void)
 411 {
 412         int ret = nf_ct_extend_register(&event_extend);
 413         if (ret < 0)
 414                 pr_err("nf_ct_event: Unable to register event extension.\n");
 415         return ret;
 416 }
 417
 418 void nf_conntrack_ecache_fini(void)
 419 {
 420         nf_ct_extend_unregister(&event_extend);
 421 }