net/netfilter/core.c

   1 /* netfilter.c: look after the filters for various protocols.
   2  * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
   3  *
   4  * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
   5  * way.
   6  *
   7  * This code is GPL.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/netfilter.h>
  11 #include <net/protocol.h>
  12 #include <linux/init.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/wait.h>
  15 #include <linux/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/if.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/netfilter_ipv6.h>
  20 #include <linux/inetdevice.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/mutex.h>
  23 #include <linux/mm.h>
  24 #include <linux/rcupdate.h>
  25 #include <net/net_namespace.h>
  26 #include <net/netfilter/nf_queue.h>
  27 #include <net/sock.h>
  28
  29 #include "nf_internals.h"
  30
  31 const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
  32 EXPORT_SYMBOL_GPL(nf_ipv6_ops);
  33
  34 DEFINE_PER_CPU(bool, nf_skb_duplicated);
  35 EXPORT_SYMBOL_GPL(nf_skb_duplicated);
  36
  37 #ifdef CONFIG_JUMP_LABEL
  38 struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
  39 EXPORT_SYMBOL(nf_hooks_needed);
  40 #endif
  41
  42 static DEFINE_MUTEX(nf_hook_mutex);
  43
  44 /* max hooks per family/hooknum */
  45 #define MAX_HOOK_COUNT          1024
  46
  47 #define nf_entry_dereference(e) \
  48         rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
  49
  50 static struct nf_hook_entries *allocate_hook_entries_size(u16 num)
  51 {
  52         struct nf_hook_entries *e;
  53         size_t alloc = sizeof(*e) +
  54                        sizeof(struct nf_hook_entry) * num +
  55                        sizeof(struct nf_hook_ops *) * num +
  56                        sizeof(struct nf_hook_entries_rcu_head);
  57
  58         if (num == 0)
  59                 return NULL;
  60
  61         e = kvzalloc(alloc, GFP_KERNEL);
  62         if (e)
  63                 e->num_hook_entries = num;
  64         return e;
  65 }
  66
  67 static void __nf_hook_entries_free(struct rcu_head *h)
  68 {
  69         struct nf_hook_entries_rcu_head *head;
  70
  71         head = container_of(h, struct nf_hook_entries_rcu_head, head);
  72         kvfree(head->allocation);
  73 }
  74
  75 static void nf_hook_entries_free(struct nf_hook_entries *e)
  76 {
  77         struct nf_hook_entries_rcu_head *head;
  78         struct nf_hook_ops **ops;
  79         unsigned int num;
  80
  81         if (!e)
  82                 return;
  83
  84         num = e->num_hook_entries;
  85         ops = nf_hook_entries_get_hook_ops(e);
  86         head = (void *)&ops[num];
  87         head->allocation = e;
  88         call_rcu(&head->head, __nf_hook_entries_free);
  89 }
  90
  91 static unsigned int accept_all(void *priv,
  92                                struct sk_buff *skb,
  93                                const struct nf_hook_state *state)
  94 {
  95         return NF_ACCEPT; /* ACCEPT makes nf_hook_slow call next hook */
  96 }
  97
  98 static const struct nf_hook_ops dummy_ops = {
  99         .hook = accept_all,
 100         .priority = INT_MIN,
 101 };
 102
 103 static struct nf_hook_entries *
 104 nf_hook_entries_grow(const struct nf_hook_entries *old,
 105                      const struct nf_hook_ops *reg)
 106 {
 107         unsigned int i, alloc_entries, nhooks, old_entries;
 108         struct nf_hook_ops **orig_ops = NULL;
 109         struct nf_hook_ops **new_ops;
 110         struct nf_hook_entries *new;
 111         bool inserted = false;
 112
 113         alloc_entries = 1;
 114         old_entries = old ? old->num_hook_entries : 0;
 115
 116         if (old) {
 117                 orig_ops = nf_hook_entries_get_hook_ops(old);
 118
 119                 for (i = 0; i < old_entries; i++) {
 120                         if (orig_ops[i] != &dummy_ops)
 121                                 alloc_entries++;
 122                 }
 123         }
 124
 125         if (alloc_entries > MAX_HOOK_COUNT)
 126                 return ERR_PTR(-E2BIG);
 127
 128         new = allocate_hook_entries_size(alloc_entries);
 129         if (!new)
 130                 return ERR_PTR(-ENOMEM);
 131
 132         new_ops = nf_hook_entries_get_hook_ops(new);
 133
 134         i = 0;
 135         nhooks = 0;
 136         while (i < old_entries) {
 137                 if (orig_ops[i] == &dummy_ops) {
 138                         ++i;
 139                         continue;
 140                 }
 141
 142                 if (inserted || reg->priority > orig_ops[i]->priority) {
 143                         new_ops[nhooks] = (void *)orig_ops[i];
 144                         new->hooks[nhooks] = old->hooks[i];
 145                         i++;
 146                 } else {
 147                         new_ops[nhooks] = (void *)reg;
 148                         new->hooks[nhooks].hook = reg->hook;
 149                         new->hooks[nhooks].priv = reg->priv;
 150                         inserted = true;
 151                 }
 152                 nhooks++;
 153         }
 154
 155         if (!inserted) {
 156                 new_ops[nhooks] = (void *)reg;
 157                 new->hooks[nhooks].hook = reg->hook;
 158                 new->hooks[nhooks].priv = reg->priv;
 159         }
 160
 161         return new;
 162 }
 163
 164 static void hooks_validate(const struct nf_hook_entries *hooks)
 165 {
 166 #ifdef CONFIG_DEBUG_MISC
 167         struct nf_hook_ops **orig_ops;
 168         int prio = INT_MIN;
 169         size_t i = 0;
 170
 171         orig_ops = nf_hook_entries_get_hook_ops(hooks);
 172
 173         for (i = 0; i < hooks->num_hook_entries; i++) {
 174                 if (orig_ops[i] == &dummy_ops)
 175                         continue;
 176
 177                 WARN_ON(orig_ops[i]->priority < prio);
 178
 179                 if (orig_ops[i]->priority > prio)
 180                         prio = orig_ops[i]->priority;
 181         }
 182 #endif
 183 }
 184
 185 int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
 186                                 const struct nf_hook_ops *reg)
 187 {
 188         struct nf_hook_entries *new_hooks;
 189         struct nf_hook_entries *p;
 190
 191         p = rcu_dereference_raw(*pp);
 192         new_hooks = nf_hook_entries_grow(p, reg);
 193         if (IS_ERR(new_hooks))
 194                 return PTR_ERR(new_hooks);
 195
 196         hooks_validate(new_hooks);
 197
 198         rcu_assign_pointer(*pp, new_hooks);
 199
 200         BUG_ON(p == new_hooks);
 201         nf_hook_entries_free(p);
 202         return 0;
 203 }
 204 EXPORT_SYMBOL_GPL(nf_hook_entries_insert_raw);
 205
 206 /*
 207  * __nf_hook_entries_try_shrink - try to shrink hook array
 208  *
 209  * @old -- current hook blob at @pp
 210  * @pp -- location of hook blob
 211  *
 212  * Hook unregistration must always succeed, so to-be-removed hooks
 213  * are replaced by a dummy one that will just move to next hook.
 214  *
 215  * This counts the current dummy hooks, attempts to allocate new blob,
 216  * copies the live hooks, then replaces and discards old one.
 217  *
 218  * return values:
 219  *
 220  * Returns address to free, or NULL.
 221  */
 222 static void *__nf_hook_entries_try_shrink(struct nf_hook_entries *old,
 223                                           struct nf_hook_entries __rcu **pp)
 224 {
 225         unsigned int i, j, skip = 0, hook_entries;
 226         struct nf_hook_entries *new = NULL;
 227         struct nf_hook_ops **orig_ops;
 228         struct nf_hook_ops **new_ops;
 229
 230         if (WARN_ON_ONCE(!old))
 231                 return NULL;
 232
 233         orig_ops = nf_hook_entries_get_hook_ops(old);
 234         for (i = 0; i < old->num_hook_entries; i++) {
 235                 if (orig_ops[i] == &dummy_ops)
 236                         skip++;
 237         }
 238
 239         /* if skip == hook_entries all hooks have been removed */
 240         hook_entries = old->num_hook_entries;
 241         if (skip == hook_entries)
 242                 goto out_assign;
 243
 244         if (skip == 0)
 245                 return NULL;
 246
 247         hook_entries -= skip;
 248         new = allocate_hook_entries_size(hook_entries);
 249         if (!new)
 250                 return NULL;
 251
 252         new_ops = nf_hook_entries_get_hook_ops(new);
 253         for (i = 0, j = 0; i < old->num_hook_entries; i++) {
 254                 if (orig_ops[i] == &dummy_ops)
 255                         continue;
 256                 new->hooks[j] = old->hooks[i];
 257                 new_ops[j] = (void *)orig_ops[i];
 258                 j++;
 259         }
 260         hooks_validate(new);
 261 out_assign:
 262         rcu_assign_pointer(*pp, new);
 263         return old;
 264 }
 265
 266 static struct nf_hook_entries __rcu **
 267 nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
 268                    struct net_device *dev)
 269 {
 270         switch (pf) {
 271         case NFPROTO_NETDEV:
 272                 break;
 273 #ifdef CONFIG_NETFILTER_FAMILY_ARP
 274         case NFPROTO_ARP:
 275                 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_arp) <= hooknum))
 276                         return NULL;
 277                 return net->nf.hooks_arp + hooknum;
 278 #endif
 279 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 280         case NFPROTO_BRIDGE:
 281                 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= hooknum))
 282                         return NULL;
 283                 return net->nf.hooks_bridge + hooknum;
 284 #endif
 285 #ifdef CONFIG_NETFILTER_INGRESS
 286         case NFPROTO_INET:
 287                 if (WARN_ON_ONCE(hooknum != NF_INET_INGRESS))
 288                         return NULL;
 289                 if (!dev || dev_net(dev) != net) {
 290                         WARN_ON_ONCE(1);
 291                         return NULL;
 292                 }
 293                 return &dev->nf_hooks_ingress;
 294 #endif
 295         case NFPROTO_IPV4:
 296                 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= hooknum))
 297                         return NULL;
 298                 return net->nf.hooks_ipv4 + hooknum;
 299         case NFPROTO_IPV6:
 300                 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv6) <= hooknum))
 301                         return NULL;
 302                 return net->nf.hooks_ipv6 + hooknum;
 303 #if IS_ENABLED(CONFIG_DECNET)
 304         case NFPROTO_DECNET:
 305                 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_decnet) <= hooknum))
 306                         return NULL;
 307                 return net->nf.hooks_decnet + hooknum;
 308 #endif
 309         default:
 310                 WARN_ON_ONCE(1);
 311                 return NULL;
 312         }
 313
 314 #ifdef CONFIG_NETFILTER_INGRESS
 315         if (hooknum == NF_NETDEV_INGRESS) {
 316                 if (dev && dev_net(dev) == net)
 317                         return &dev->nf_hooks_ingress;
 318         }
 319 #endif
 320         WARN_ON_ONCE(1);
 321         return NULL;
 322 }
 323
 324 static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
 325                             int hooknum)
 326 {
 327 #ifndef CONFIG_NETFILTER_INGRESS
 328         if (reg->hooknum == hooknum)
 329                 return -EOPNOTSUPP;
 330 #endif
 331         if (reg->hooknum != hooknum ||
 332             !reg->dev || dev_net(reg->dev) != net)
 333                 return -EINVAL;
 334
 335         return 0;
 336 }
 337
 338 static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
 339 {
 340         if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
 341             (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
 342                 return true;
 343
 344         return false;
 345 }
 346
 347 static void nf_static_key_inc(const struct nf_hook_ops *reg, int pf)
 348 {
 349 #ifdef CONFIG_JUMP_LABEL
 350         int hooknum;
 351
 352         if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
 353                 pf = NFPROTO_NETDEV;
 354                 hooknum = NF_NETDEV_INGRESS;
 355         } else {
 356                 hooknum = reg->hooknum;
 357         }
 358         static_key_slow_inc(&nf_hooks_needed[pf][hooknum]);
 359 #endif
 360 }
 361
 362 static void nf_static_key_dec(const struct nf_hook_ops *reg, int pf)
 363 {
 364 #ifdef CONFIG_JUMP_LABEL
 365         int hooknum;
 366
 367         if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
 368                 pf = NFPROTO_NETDEV;
 369                 hooknum = NF_NETDEV_INGRESS;
 370         } else {
 371                 hooknum = reg->hooknum;
 372         }
 373         static_key_slow_dec(&nf_hooks_needed[pf][hooknum]);
 374 #endif
 375 }
 376
 377 static int __nf_register_net_hook(struct net *net, int pf,
 378                                   const struct nf_hook_ops *reg)
 379 {
 380         struct nf_hook_entries *p, *new_hooks;
 381         struct nf_hook_entries __rcu **pp;
 382         int err;
 383
 384         switch (pf) {
 385         case NFPROTO_NETDEV:
 386                 err = nf_ingress_check(net, reg, NF_NETDEV_INGRESS);
 387                 if (err < 0)
 388                         return err;
 389                 break;
 390         case NFPROTO_INET:
 391                 if (reg->hooknum != NF_INET_INGRESS)
 392                         break;
 393
 394                 err = nf_ingress_check(net, reg, NF_INET_INGRESS);
 395                 if (err < 0)
 396                         return err;
 397                 break;
 398         }
 399
 400         pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
 401         if (!pp)
 402                 return -EINVAL;
 403
 404         mutex_lock(&nf_hook_mutex);
 405
 406         p = nf_entry_dereference(*pp);
 407         new_hooks = nf_hook_entries_grow(p, reg);
 408
 409         if (!IS_ERR(new_hooks)) {
 410                 hooks_validate(new_hooks);
 411                 rcu_assign_pointer(*pp, new_hooks);
 412         }
 413
 414         mutex_unlock(&nf_hook_mutex);
 415         if (IS_ERR(new_hooks))
 416                 return PTR_ERR(new_hooks);
 417
 418 #ifdef CONFIG_NETFILTER_INGRESS
 419         if (nf_ingress_hook(reg, pf))
 420                 net_inc_ingress_queue();
 421 #endif
 422         nf_static_key_inc(reg, pf);
 423
 424         BUG_ON(p == new_hooks);
 425         nf_hook_entries_free(p);
 426         return 0;
 427 }
 428
 429 /*
 430  * nf_remove_net_hook - remove a hook from blob
 431  *
 432  * @oldp: current address of hook blob
 433  * @unreg: hook to unregister
 434  *
 435  * This cannot fail, hook unregistration must always succeed.
 436  * Therefore replace the to-be-removed hook with a dummy hook.
 437  */
 438 static bool nf_remove_net_hook(struct nf_hook_entries *old,
 439                                const struct nf_hook_ops *unreg)
 440 {
 441         struct nf_hook_ops **orig_ops;
 442         unsigned int i;
 443
 444         orig_ops = nf_hook_entries_get_hook_ops(old);
 445         for (i = 0; i < old->num_hook_entries; i++) {
 446                 if (orig_ops[i] != unreg)
 447                         continue;
 448                 WRITE_ONCE(old->hooks[i].hook, accept_all);
 449                 WRITE_ONCE(orig_ops[i], (void *)&dummy_ops);
 450                 return true;
 451         }
 452
 453         return false;
 454 }
 455
 456 static void __nf_unregister_net_hook(struct net *net, int pf,
 457                                      const struct nf_hook_ops *reg)
 458 {
 459         struct nf_hook_entries __rcu **pp;
 460         struct nf_hook_entries *p;
 461
 462         pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
 463         if (!pp)
 464                 return;
 465
 466         mutex_lock(&nf_hook_mutex);
 467
 468         p = nf_entry_dereference(*pp);
 469         if (WARN_ON_ONCE(!p)) {
 470                 mutex_unlock(&nf_hook_mutex);
 471                 return;
 472         }
 473
 474         if (nf_remove_net_hook(p, reg)) {
 475 #ifdef CONFIG_NETFILTER_INGRESS
 476                 if (nf_ingress_hook(reg, pf))
 477                         net_dec_ingress_queue();
 478 #endif
 479                 nf_static_key_dec(reg, pf);
 480         } else {
 481                 WARN_ONCE(1, "hook not found, pf %d num %d", pf, reg->hooknum);
 482         }
 483
 484         p = __nf_hook_entries_try_shrink(p, pp);
 485         mutex_unlock(&nf_hook_mutex);
 486         if (!p)
 487                 return;
 488
 489         nf_queue_nf_hook_drop(net);
 490         nf_hook_entries_free(p);
 491 }
 492
 493 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 494 {
 495         if (reg->pf == NFPROTO_INET) {
 496                 if (reg->hooknum == NF_INET_INGRESS) {
 497                         __nf_unregister_net_hook(net, NFPROTO_INET, reg);
 498                 } else {
 499                         __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
 500                         __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
 501                 }
 502         } else {
 503                 __nf_unregister_net_hook(net, reg->pf, reg);
 504         }
 505 }
 506 EXPORT_SYMBOL(nf_unregister_net_hook);
 507
 508 void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
 509                                 const struct nf_hook_ops *reg)
 510 {
 511         struct nf_hook_entries *p;
 512
 513         p = rcu_dereference_raw(*pp);
 514         if (nf_remove_net_hook(p, reg)) {
 515                 p = __nf_hook_entries_try_shrink(p, pp);
 516                 nf_hook_entries_free(p);
 517         }
 518 }
 519 EXPORT_SYMBOL_GPL(nf_hook_entries_delete_raw);
 520
 521 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 522 {
 523         int err;
 524
 525         if (reg->pf == NFPROTO_INET) {
 526                 if (reg->hooknum == NF_INET_INGRESS) {
 527                         err = __nf_register_net_hook(net, NFPROTO_INET, reg);
 528                         if (err < 0)
 529                                 return err;
 530                 } else {
 531                         err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
 532                         if (err < 0)
 533                                 return err;
 534
 535                         err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
 536                         if (err < 0) {
 537                                 __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
 538                                 return err;
 539                         }
 540                 }
 541         } else {
 542                 err = __nf_register_net_hook(net, reg->pf, reg);
 543                 if (err < 0)
 544                         return err;
 545         }
 546
 547         return 0;
 548 }
 549 EXPORT_SYMBOL(nf_register_net_hook);
 550
 551 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 552                           unsigned int n)
 553 {
 554         unsigned int i;
 555         int err = 0;
 556
 557         for (i = 0; i < n; i++) {
 558                 err = nf_register_net_hook(net, &reg[i]);
 559                 if (err)
 560                         goto err;
 561         }
 562         return err;
 563
 564 err:
 565         if (i > 0)
 566                 nf_unregister_net_hooks(net, reg, i);
 567         return err;
 568 }
 569 EXPORT_SYMBOL(nf_register_net_hooks);
 570
 571 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
 572                              unsigned int hookcount)
 573 {
 574         unsigned int i;
 575
 576         for (i = 0; i < hookcount; i++)
 577                 nf_unregister_net_hook(net, &reg[i]);
 578 }
 579 EXPORT_SYMBOL(nf_unregister_net_hooks);
 580
 581 /* Returns 1 if okfn() needs to be executed by the caller,
 582  * -EPERM for NF_DROP, 0 otherwise.  Caller must hold rcu_read_lock. */
 583 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
 584                  const struct nf_hook_entries *e, unsigned int s)
 585 {
 586         unsigned int verdict;
 587         int ret;
 588
 589         for (; s < e->num_hook_entries; s++) {
 590                 verdict = nf_hook_entry_hookfn(&e->hooks[s], skb, state);
 591                 switch (verdict & NF_VERDICT_MASK) {
 592                 case NF_ACCEPT:
 593                         break;
 594                 case NF_DROP:
 595                         kfree_skb_reason(skb,
 596                                          SKB_DROP_REASON_NETFILTER_DROP);
 597                         ret = NF_DROP_GETERR(verdict);
 598                         if (ret == 0)
 599                                 ret = -EPERM;
 600                         return ret;
 601                 case NF_QUEUE:
 602                         ret = nf_queue(skb, state, s, verdict);
 603                         if (ret == 1)
 604                                 continue;
 605                         return ret;
 606                 default:
 607                         /* Implicit handling for NF_STOLEN, as well as any other
 608                          * non conventional verdicts.
 609                          */
 610                         return 0;
 611                 }
 612         }
 613
 614         return 1;
 615 }
 616 EXPORT_SYMBOL(nf_hook_slow);
 617
 618 void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
 619                        const struct nf_hook_entries *e)
 620 {
 621         struct sk_buff *skb, *next;
 622         struct list_head sublist;
 623         int ret;
 624
 625         INIT_LIST_HEAD(&sublist);
 626
 627         list_for_each_entry_safe(skb, next, head, list) {
 628                 skb_list_del_init(skb);
 629                 ret = nf_hook_slow(skb, state, e, 0);
 630                 if (ret == 1)
 631                         list_add_tail(&skb->list, &sublist);
 632         }
 633         /* Put passed packets back on main list */
 634         list_splice(&sublist, head);
 635 }
 636 EXPORT_SYMBOL(nf_hook_slow_list);
 637
 638 /* This needs to be compiled in any case to avoid dependencies between the
 639  * nfnetlink_queue code and nf_conntrack.
 640  */
 641 struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly;
 642 EXPORT_SYMBOL_GPL(nfnl_ct_hook);
 643
 644 struct nf_ct_hook __rcu *nf_ct_hook __read_mostly;
 645 EXPORT_SYMBOL_GPL(nf_ct_hook);
 646
 647 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 648 /* This does not belong here, but locally generated errors need it if connection
 649    tracking in use: without this, connection may not be in hash table, and hence
 650    manufactured ICMP or RST packets will not be associated with it. */
 651 void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
 652                 __rcu __read_mostly;
 653 EXPORT_SYMBOL(ip_ct_attach);
 654
 655 struct nf_nat_hook __rcu *nf_nat_hook __read_mostly;
 656 EXPORT_SYMBOL_GPL(nf_nat_hook);
 657
 658 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
 659 {
 660         void (*attach)(struct sk_buff *, const struct sk_buff *);
 661
 662         if (skb->_nfct) {
 663                 rcu_read_lock();
 664                 attach = rcu_dereference(ip_ct_attach);
 665                 if (attach)
 666                         attach(new, skb);
 667                 rcu_read_unlock();
 668         }
 669 }
 670 EXPORT_SYMBOL(nf_ct_attach);
 671
 672 void nf_conntrack_destroy(struct nf_conntrack *nfct)
 673 {
 674         struct nf_ct_hook *ct_hook;
 675
 676         rcu_read_lock();
 677         ct_hook = rcu_dereference(nf_ct_hook);
 678         BUG_ON(ct_hook == NULL);
 679         ct_hook->destroy(nfct);
 680         rcu_read_unlock();
 681 }
 682 EXPORT_SYMBOL(nf_conntrack_destroy);
 683
 684 bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
 685                          const struct sk_buff *skb)
 686 {
 687         struct nf_ct_hook *ct_hook;
 688         bool ret = false;
 689
 690         rcu_read_lock();
 691         ct_hook = rcu_dereference(nf_ct_hook);
 692         if (ct_hook)
 693                 ret = ct_hook->get_tuple_skb(dst_tuple, skb);
 694         rcu_read_unlock();
 695         return ret;
 696 }
 697 EXPORT_SYMBOL(nf_ct_get_tuple_skb);
 698
 699 /* Built-in default zone used e.g. by modules. */
 700 const struct nf_conntrack_zone nf_ct_zone_dflt = {
 701         .id     = NF_CT_DEFAULT_ZONE_ID,
 702         .dir    = NF_CT_DEFAULT_ZONE_DIR,
 703 };
 704 EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
 705 #endif /* CONFIG_NF_CONNTRACK */
 706
 707 static void __net_init
 708 __netfilter_net_init(struct nf_hook_entries __rcu **e, int max)
 709 {
 710         int h;
 711
 712         for (h = 0; h < max; h++)
 713                 RCU_INIT_POINTER(e[h], NULL);
 714 }
 715
 716 static int __net_init netfilter_net_init(struct net *net)
 717 {
 718         __netfilter_net_init(net->nf.hooks_ipv4, ARRAY_SIZE(net->nf.hooks_ipv4));
 719         __netfilter_net_init(net->nf.hooks_ipv6, ARRAY_SIZE(net->nf.hooks_ipv6));
 720 #ifdef CONFIG_NETFILTER_FAMILY_ARP
 721         __netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
 722 #endif
 723 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
 724         __netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
 725 #endif
 726 #if IS_ENABLED(CONFIG_DECNET)
 727         __netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(net->nf.hooks_decnet));
 728 #endif
 729
 730 #ifdef CONFIG_PROC_FS
 731         net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
 732                                                 net->proc_net);
 733         if (!net->nf.proc_netfilter) {
 734                 if (!net_eq(net, &init_net))
 735                         pr_err("cannot create netfilter proc entry");
 736
 737                 return -ENOMEM;
 738         }
 739 #endif
 740
 741         return 0;
 742 }
 743
 744 static void __net_exit netfilter_net_exit(struct net *net)
 745 {
 746         remove_proc_entry("netfilter", net->proc_net);
 747 }
 748
 749 static struct pernet_operations netfilter_net_ops = {
 750         .init = netfilter_net_init,
 751         .exit = netfilter_net_exit,
 752 };
 753
 754 int __init netfilter_init(void)
 755 {
 756         int ret;
 757
 758         ret = register_pernet_subsys(&netfilter_net_ops);
 759         if (ret < 0)
 760                 goto err;
 761
 762         ret = netfilter_log_init();
 763         if (ret < 0)
 764                 goto err_pernet;
 765
 766         return 0;
 767 err_pernet:
 768         unregister_pernet_subsys(&netfilter_net_ops);
 769 err:
 770         return ret;
 771 }