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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/types.h>
  17 #include <linux/netfilter.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/stddef.h>
  21 #include <linux/err.h>
  22 #include <linux/percpu.h>
  23 #include <linux/kernel.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/slab.h>
  26 #include <linux/export.h>
  27
  28 #include <net/netfilter/nf_conntrack.h>
  29 #include <net/netfilter/nf_conntrack_core.h>
  30 #include <net/netfilter/nf_conntrack_extend.h>
  31
  32 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  33
  34 #define ECACHE_RETRY_WAIT (HZ/10)
  35
  36 enum retry_state {
  37         STATE_CONGESTED,
  38         STATE_RESTART,
  39         STATE_DONE,
  40 };
  41
  42 static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
  43 {
  44         struct nf_conn *refs[16];
  45         struct nf_conntrack_tuple_hash *h;
  46         struct hlist_nulls_node *n;
  47         unsigned int evicted = 0;
  48         enum retry_state ret = STATE_DONE;
  49
  50         spin_lock(&pcpu->lock);
  51
  52         hlist_nulls_for_each_entry(h, n, &pcpu->dying, hnnode) {
  53                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
  54                 struct nf_conntrack_ecache *e;
  55
  56                 if (!nf_ct_is_confirmed(ct))
  57                         continue;
  58
  59                 e = nf_ct_ecache_find(ct);
  60                 if (!e || e->state != NFCT_ECACHE_DESTROY_FAIL)
  61                         continue;
  62
  63                 if (nf_conntrack_event(IPCT_DESTROY, ct)) {
  64                         ret = STATE_CONGESTED;
  65                         break;
  66                 }
  67
  68                 e->state = NFCT_ECACHE_DESTROY_SENT;
  69                 refs[evicted] = ct;
  70
  71                 if (++evicted >= ARRAY_SIZE(refs)) {
  72                         ret = STATE_RESTART;
  73                         break;
  74                 }
  75         }
  76
  77         spin_unlock(&pcpu->lock);
  78
  79         /* can't _put while holding lock */
  80         while (evicted)
  81                 nf_ct_put(refs[--evicted]);
  82
  83         return ret;
  84 }
  85
  86 static void ecache_work(struct work_struct *work)
  87 {
  88         struct netns_ct *ctnet =
  89                 container_of(work, struct netns_ct, ecache_dwork.work);
  90         int cpu, delay = -1;
  91         struct ct_pcpu *pcpu;
  92
  93         local_bh_disable();
  94
  95         for_each_possible_cpu(cpu) {
  96                 enum retry_state ret;
  97
  98                 pcpu = per_cpu_ptr(ctnet->pcpu_lists, cpu);
  99
 100                 ret = ecache_work_evict_list(pcpu);
 101
 102                 switch (ret) {
 103                 case STATE_CONGESTED:
 104                         delay = ECACHE_RETRY_WAIT;
 105                         goto out;
 106                 case STATE_RESTART:
 107                         delay = 0;
 108                         break;
 109                 case STATE_DONE:
 110                         break;
 111                 }
 112         }
 113
 114  out:
 115         local_bh_enable();
 116
 117         ctnet->ecache_dwork_pending = delay > 0;
 118         if (delay >= 0)
 119                 schedule_delayed_work(&ctnet->ecache_dwork, delay);
 120 }
 121
 122 int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
 123                                   u32 portid, int report)
 124 {
 125         int ret = 0;
 126         struct net *net = nf_ct_net(ct);
 127         struct nf_ct_event_notifier *notify;
 128         struct nf_conntrack_ecache *e;
 129
 130         rcu_read_lock();
 131         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
 132         if (!notify)
 133                 goto out_unlock;
 134
 135         e = nf_ct_ecache_find(ct);
 136         if (!e)
 137                 goto out_unlock;
 138
 139         if (nf_ct_is_confirmed(ct)) {
 140                 struct nf_ct_event item = {
 141                         .ct     = ct,
 142                         .portid = e->portid ? e->portid : portid,
 143                         .report = report
 144                 };
 145                 /* This is a resent of a destroy event? If so, skip missed */
 146                 unsigned long missed = e->portid ? 0 : e->missed;
 147
 148                 if (!((eventmask | missed) & e->ctmask))
 149                         goto out_unlock;
 150
 151                 ret = notify->fcn(eventmask | missed, &item);
 152                 if (unlikely(ret < 0 || missed)) {
 153                         spin_lock_bh(&ct->lock);
 154                         if (ret < 0) {
 155                                 /* This is a destroy event that has been
 156                                  * triggered by a process, we store the PORTID
 157                                  * to include it in the retransmission.
 158                                  */
 159                                 if (eventmask & (1 << IPCT_DESTROY)) {
 160                                         if (e->portid == 0 && portid != 0)
 161                                                 e->portid = portid;
 162                                         e->state = NFCT_ECACHE_DESTROY_FAIL;
 163                                 } else {
 164                                         e->missed |= eventmask;
 165                                 }
 166                         } else {
 167                                 e->missed &= ~missed;
 168                         }
 169                         spin_unlock_bh(&ct->lock);
 170                 }
 171         }
 172 out_unlock:
 173         rcu_read_unlock();
 174         return ret;
 175 }
 176 EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
 177
 178 /* deliver cached events and clear cache entry - must be called with locally
 179  * disabled softirqs */
 180 void nf_ct_deliver_cached_events(struct nf_conn *ct)
 181 {
 182         struct net *net = nf_ct_net(ct);
 183         unsigned long events, missed;
 184         struct nf_ct_event_notifier *notify;
 185         struct nf_conntrack_ecache *e;
 186         struct nf_ct_event item;
 187         int ret;
 188
 189         rcu_read_lock();
 190         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
 191         if (notify == NULL)
 192                 goto out_unlock;
 193
 194         e = nf_ct_ecache_find(ct);
 195         if (e == NULL)
 196                 goto out_unlock;
 197
 198         events = xchg(&e->cache, 0);
 199
 200         if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct))
 201                 goto out_unlock;
 202
 203         /* We make a copy of the missed event cache without taking
 204          * the lock, thus we may send missed events twice. However,
 205          * this does not harm and it happens very rarely. */
 206         missed = e->missed;
 207
 208         if (!((events | missed) & e->ctmask))
 209                 goto out_unlock;
 210
 211         item.ct = ct;
 212         item.portid = 0;
 213         item.report = 0;
 214
 215         ret = notify->fcn(events | missed, &item);
 216
 217         if (likely(ret == 0 && !missed))
 218                 goto out_unlock;
 219
 220         spin_lock_bh(&ct->lock);
 221         if (ret < 0)
 222                 e->missed |= events;
 223         else
 224                 e->missed &= ~missed;
 225         spin_unlock_bh(&ct->lock);
 226
 227 out_unlock:
 228         rcu_read_unlock();
 229 }
 230 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
 231
 232 void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
 233                                struct nf_conntrack_expect *exp,
 234                                u32 portid, int report)
 235
 236 {
 237         struct net *net = nf_ct_exp_net(exp);
 238         struct nf_exp_event_notifier *notify;
 239         struct nf_conntrack_ecache *e;
 240
 241         rcu_read_lock();
 242         notify = rcu_dereference(net->ct.nf_expect_event_cb);
 243         if (!notify)
 244                 goto out_unlock;
 245
 246         e = nf_ct_ecache_find(exp->master);
 247         if (!e)
 248                 goto out_unlock;
 249
 250         if (e->expmask & (1 << event)) {
 251                 struct nf_exp_event item = {
 252                         .exp    = exp,
 253                         .portid = portid,
 254                         .report = report
 255                 };
 256                 notify->fcn(1 << event, &item);
 257         }
 258 out_unlock:
 259         rcu_read_unlock();
 260 }
 261
 262 int nf_conntrack_register_notifier(struct net *net,
 263                                    struct nf_ct_event_notifier *new)
 264 {
 265         int ret;
 266         struct nf_ct_event_notifier *notify;
 267
 268         mutex_lock(&nf_ct_ecache_mutex);
 269         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 270                                            lockdep_is_held(&nf_ct_ecache_mutex));
 271         if (notify != NULL) {
 272                 ret = -EBUSY;
 273                 goto out_unlock;
 274         }
 275         rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
 276         ret = 0;
 277
 278 out_unlock:
 279         mutex_unlock(&nf_ct_ecache_mutex);
 280         return ret;
 281 }
 282 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 283
 284 void nf_conntrack_unregister_notifier(struct net *net,
 285                                       struct nf_ct_event_notifier *new)
 286 {
 287         struct nf_ct_event_notifier *notify;
 288
 289         mutex_lock(&nf_ct_ecache_mutex);
 290         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 291                                            lockdep_is_held(&nf_ct_ecache_mutex));
 292         BUG_ON(notify != new);
 293         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 294         mutex_unlock(&nf_ct_ecache_mutex);
 295         /* synchronize_rcu() is called from ctnetlink_exit. */
 296 }
 297 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 298
 299 int nf_ct_expect_register_notifier(struct net *net,
 300                                    struct nf_exp_event_notifier *new)
 301 {
 302         int ret;
 303         struct nf_exp_event_notifier *notify;
 304
 305         mutex_lock(&nf_ct_ecache_mutex);
 306         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 307                                            lockdep_is_held(&nf_ct_ecache_mutex));
 308         if (notify != NULL) {
 309                 ret = -EBUSY;
 310                 goto out_unlock;
 311         }
 312         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
 313         ret = 0;
 314
 315 out_unlock:
 316         mutex_unlock(&nf_ct_ecache_mutex);
 317         return ret;
 318 }
 319 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 320
 321 void nf_ct_expect_unregister_notifier(struct net *net,
 322                                       struct nf_exp_event_notifier *new)
 323 {
 324         struct nf_exp_event_notifier *notify;
 325
 326         mutex_lock(&nf_ct_ecache_mutex);
 327         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 328                                            lockdep_is_held(&nf_ct_ecache_mutex));
 329         BUG_ON(notify != new);
 330         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
 331         mutex_unlock(&nf_ct_ecache_mutex);
 332         /* synchronize_rcu() is called from ctnetlink_exit. */
 333 }
 334 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 335
 336 #define NF_CT_EVENTS_DEFAULT 1
 337 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 338
 339 static const struct nf_ct_ext_type event_extend = {
 340         .len    = sizeof(struct nf_conntrack_ecache),
 341         .align  = __alignof__(struct nf_conntrack_ecache),
 342         .id     = NF_CT_EXT_ECACHE,
 343 };
 344
 345 void nf_conntrack_ecache_pernet_init(struct net *net)
 346 {
 347         net->ct.sysctl_events = nf_ct_events;
 348         INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work);
 349 }
 350
 351 void nf_conntrack_ecache_pernet_fini(struct net *net)
 352 {
 353         cancel_delayed_work_sync(&net->ct.ecache_dwork);
 354 }
 355
 356 int nf_conntrack_ecache_init(void)
 357 {
 358         int ret = nf_ct_extend_register(&event_extend);
 359         if (ret < 0)
 360                 pr_err("Unable to register event extension\n");
 361
 362         BUILD_BUG_ON(__IPCT_MAX >= 16); /* ctmask, missed use u16 */
 363
 364         return ret;
 365 }
 366
 367 void nf_conntrack_ecache_fini(void)
 368 {
 369         nf_ct_extend_unregister(&event_extend);
 370 }