net/netfilter/nf_conntrack_proto.c

   1 /* L3/L4 protocol support for nf_conntrack. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <[email protected]>
   5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  * (C) 2006-2012 Patrick McHardy <[email protected]>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/mutex.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/stddef.h>
  20 #include <linux/err.h>
  21 #include <linux/percpu.h>
  22 #include <linux/notifier.h>
  23 #include <linux/kernel.h>
  24 #include <linux/netdevice.h>
  25
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_l3proto.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_core.h>
  30
  31 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[PF_MAX] __read_mostly;
  32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __read_mostly;
  33 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  34
  35 static DEFINE_MUTEX(nf_ct_proto_mutex);
  36
  37 #ifdef CONFIG_SYSCTL
  38 static int
  39 nf_ct_register_sysctl(struct net *net,
  40                       struct ctl_table_header **header,
  41                       const char *path,
  42                       struct ctl_table *table)
  43 {
  44         if (*header == NULL) {
  45                 *header = register_net_sysctl(net, path, table);
  46                 if (*header == NULL)
  47                         return -ENOMEM;
  48         }
  49
  50         return 0;
  51 }
  52
  53 static void
  54 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  55                         struct ctl_table **table,
  56                         unsigned int users)
  57 {
  58         if (users > 0)
  59                 return;
  60
  61         unregister_net_sysctl_table(*header);
  62         kfree(*table);
  63         *header = NULL;
  64         *table = NULL;
  65 }
  66 #endif
  67
  68 struct nf_conntrack_l4proto *
  69 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
  70 {
  71         if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
  72                 return &nf_conntrack_l4proto_generic;
  73
  74         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
  75 }
  76 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
  77
  78 /* this is guaranteed to always return a valid protocol helper, since
  79  * it falls back to generic_protocol */
  80 struct nf_conntrack_l3proto *
  81 nf_ct_l3proto_find_get(u_int16_t l3proto)
  82 {
  83         struct nf_conntrack_l3proto *p;
  84
  85         rcu_read_lock();
  86         p = __nf_ct_l3proto_find(l3proto);
  87         if (!try_module_get(p->me))
  88                 p = &nf_conntrack_l3proto_generic;
  89         rcu_read_unlock();
  90
  91         return p;
  92 }
  93 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
  94
  95 int
  96 nf_ct_l3proto_try_module_get(unsigned short l3proto)
  97 {
  98         int ret;
  99         struct nf_conntrack_l3proto *p;
 100
 101 retry:  p = nf_ct_l3proto_find_get(l3proto);
 102         if (p == &nf_conntrack_l3proto_generic) {
 103                 ret = request_module("nf_conntrack-%d", l3proto);
 104                 if (!ret)
 105                         goto retry;
 106
 107                 return -EPROTOTYPE;
 108         }
 109
 110         return 0;
 111 }
 112 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 113
 114 void nf_ct_l3proto_module_put(unsigned short l3proto)
 115 {
 116         struct nf_conntrack_l3proto *p;
 117
 118         /* rcu_read_lock not necessary since the caller holds a reference, but
 119          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 120          */
 121         rcu_read_lock();
 122         p = __nf_ct_l3proto_find(l3proto);
 123         module_put(p->me);
 124         rcu_read_unlock();
 125 }
 126 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 127
 128 int nf_ct_netns_get(struct net *net, u8 nfproto)
 129 {
 130         const struct nf_conntrack_l3proto *l3proto;
 131         int ret;
 132
 133         might_sleep();
 134
 135         ret = nf_ct_l3proto_try_module_get(nfproto);
 136         if (ret < 0)
 137                 return ret;
 138
 139         /* we already have a reference, can't fail */
 140         rcu_read_lock();
 141         l3proto = __nf_ct_l3proto_find(nfproto);
 142         rcu_read_unlock();
 143
 144         if (!l3proto->net_ns_get)
 145                 return 0;
 146
 147         ret = l3proto->net_ns_get(net);
 148         if (ret < 0)
 149                 nf_ct_l3proto_module_put(nfproto);
 150
 151         return ret;
 152 }
 153 EXPORT_SYMBOL_GPL(nf_ct_netns_get);
 154
 155 void nf_ct_netns_put(struct net *net, u8 nfproto)
 156 {
 157         const struct nf_conntrack_l3proto *l3proto;
 158
 159         might_sleep();
 160
 161         /* same as nf_conntrack_netns_get(), reference assumed */
 162         rcu_read_lock();
 163         l3proto = __nf_ct_l3proto_find(nfproto);
 164         rcu_read_unlock();
 165
 166         if (WARN_ON(!l3proto))
 167                 return;
 168
 169         if (l3proto->net_ns_put)
 170                 l3proto->net_ns_put(net);
 171
 172         nf_ct_l3proto_module_put(nfproto);
 173 }
 174 EXPORT_SYMBOL_GPL(nf_ct_netns_put);
 175
 176 struct nf_conntrack_l4proto *
 177 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 178 {
 179         struct nf_conntrack_l4proto *p;
 180
 181         rcu_read_lock();
 182         p = __nf_ct_l4proto_find(l3num, l4num);
 183         if (!try_module_get(p->me))
 184                 p = &nf_conntrack_l4proto_generic;
 185         rcu_read_unlock();
 186
 187         return p;
 188 }
 189 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
 190
 191 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
 192 {
 193         module_put(p->me);
 194 }
 195 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
 196
 197 static int kill_l3proto(struct nf_conn *i, void *data)
 198 {
 199         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 200 }
 201
 202 static int kill_l4proto(struct nf_conn *i, void *data)
 203 {
 204         struct nf_conntrack_l4proto *l4proto;
 205         l4proto = (struct nf_conntrack_l4proto *)data;
 206         return nf_ct_protonum(i) == l4proto->l4proto &&
 207                nf_ct_l3num(i) == l4proto->l3proto;
 208 }
 209
 210 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 211 {
 212         int ret = 0;
 213         struct nf_conntrack_l3proto *old;
 214
 215         if (proto->l3proto >= AF_MAX)
 216                 return -EBUSY;
 217
 218         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 219                 return -EINVAL;
 220
 221         mutex_lock(&nf_ct_proto_mutex);
 222         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 223                                         lockdep_is_held(&nf_ct_proto_mutex));
 224         if (old != &nf_conntrack_l3proto_generic) {
 225                 ret = -EBUSY;
 226                 goto out_unlock;
 227         }
 228
 229         if (proto->nlattr_tuple_size)
 230                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 231
 232         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 233
 234 out_unlock:
 235         mutex_unlock(&nf_ct_proto_mutex);
 236         return ret;
 237
 238 }
 239 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 240
 241 #ifdef CONFIG_SYSCTL
 242 extern unsigned int nf_conntrack_default_on;
 243
 244 int nf_ct_l3proto_pernet_register(struct net *net,
 245                                   struct nf_conntrack_l3proto *proto)
 246 {
 247         if (nf_conntrack_default_on == 0)
 248                 return 0;
 249
 250         return proto->net_ns_get ? proto->net_ns_get(net) : 0;
 251 }
 252 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
 253 #endif
 254
 255 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 256 {
 257         BUG_ON(proto->l3proto >= AF_MAX);
 258
 259         mutex_lock(&nf_ct_proto_mutex);
 260         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 261                                          lockdep_is_held(&nf_ct_proto_mutex)
 262                                          ) != proto);
 263         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 264                            &nf_conntrack_l3proto_generic);
 265         mutex_unlock(&nf_ct_proto_mutex);
 266
 267         synchronize_rcu();
 268 }
 269 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 270
 271 void nf_ct_l3proto_pernet_unregister(struct net *net,
 272                                      struct nf_conntrack_l3proto *proto)
 273 {
 274         /*
 275          * nf_conntrack_default_on *might* have registered hooks.
 276          * ->net_ns_put must cope with more puts() than get(), i.e.
 277          * if nf_conntrack_default_on was 0 at time of
 278          * nf_ct_l3proto_pernet_register invocation this net_ns_put()
 279          * should be a noop.
 280          */
 281         if (proto->net_ns_put)
 282                 proto->net_ns_put(net);
 283
 284         /* Remove all contrack entries for this protocol */
 285         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 286 }
 287 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
 288
 289 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 290                                               struct nf_conntrack_l4proto *l4proto)
 291 {
 292         if (l4proto->get_net_proto) {
 293                 /* statically built-in protocols use static per-net */
 294                 return l4proto->get_net_proto(net);
 295         } else if (l4proto->net_id) {
 296                 /* ... and loadable protocols use dynamic per-net */
 297                 return net_generic(net, *l4proto->net_id);
 298         }
 299         return NULL;
 300 }
 301
 302 static
 303 int nf_ct_l4proto_register_sysctl(struct net *net,
 304                                   struct nf_proto_net *pn,
 305                                   struct nf_conntrack_l4proto *l4proto)
 306 {
 307         int err = 0;
 308
 309 #ifdef CONFIG_SYSCTL
 310         if (pn->ctl_table != NULL) {
 311                 err = nf_ct_register_sysctl(net,
 312                                             &pn->ctl_table_header,
 313                                             "net/netfilter",
 314                                             pn->ctl_table);
 315                 if (err < 0) {
 316                         if (!pn->users) {
 317                                 kfree(pn->ctl_table);
 318                                 pn->ctl_table = NULL;
 319                         }
 320                 }
 321         }
 322 #endif /* CONFIG_SYSCTL */
 323         return err;
 324 }
 325
 326 static
 327 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 328                                      struct nf_proto_net *pn,
 329                                      struct nf_conntrack_l4proto *l4proto)
 330 {
 331 #ifdef CONFIG_SYSCTL
 332         if (pn->ctl_table_header != NULL)
 333                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 334                                         &pn->ctl_table,
 335                                         pn->users);
 336 #endif /* CONFIG_SYSCTL */
 337 }
 338
 339 /* FIXME: Allow NULL functions and sub in pointers to generic for
 340    them. --RR */
 341 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 342 {
 343         int ret = 0;
 344
 345         if (l4proto->l3proto >= PF_MAX)
 346                 return -EBUSY;
 347
 348         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 349             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 350                 return -EINVAL;
 351
 352         mutex_lock(&nf_ct_proto_mutex);
 353         if (!nf_ct_protos[l4proto->l3proto]) {
 354                 /* l3proto may be loaded latter. */
 355                 struct nf_conntrack_l4proto __rcu **proto_array;
 356                 int i;
 357
 358                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 359                                       sizeof(struct nf_conntrack_l4proto *),
 360                                       GFP_KERNEL);
 361                 if (proto_array == NULL) {
 362                         ret = -ENOMEM;
 363                         goto out_unlock;
 364                 }
 365
 366                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 367                         RCU_INIT_POINTER(proto_array[i],
 368                                          &nf_conntrack_l4proto_generic);
 369
 370                 /* Before making proto_array visible to lockless readers,
 371                  * we must make sure its content is committed to memory.
 372                  */
 373                 smp_wmb();
 374
 375                 nf_ct_protos[l4proto->l3proto] = proto_array;
 376         } else if (rcu_dereference_protected(
 377                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 378                         lockdep_is_held(&nf_ct_proto_mutex)
 379                         ) != &nf_conntrack_l4proto_generic) {
 380                 ret = -EBUSY;
 381                 goto out_unlock;
 382         }
 383
 384         l4proto->nla_size = 0;
 385         if (l4proto->nlattr_size)
 386                 l4proto->nla_size += l4proto->nlattr_size();
 387         if (l4proto->nlattr_tuple_size)
 388                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 389
 390         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 391                            l4proto);
 392 out_unlock:
 393         mutex_unlock(&nf_ct_proto_mutex);
 394         return ret;
 395 }
 396 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
 397
 398 int nf_ct_l4proto_pernet_register_one(struct net *net,
 399                                       struct nf_conntrack_l4proto *l4proto)
 400 {
 401         int ret = 0;
 402         struct nf_proto_net *pn = NULL;
 403
 404         if (l4proto->init_net) {
 405                 ret = l4proto->init_net(net, l4proto->l3proto);
 406                 if (ret < 0)
 407                         goto out;
 408         }
 409
 410         pn = nf_ct_l4proto_net(net, l4proto);
 411         if (pn == NULL)
 412                 goto out;
 413
 414         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 415         if (ret < 0)
 416                 goto out;
 417
 418         pn->users++;
 419 out:
 420         return ret;
 421 }
 422 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
 423
 424 void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
 425 {
 426         BUG_ON(l4proto->l3proto >= PF_MAX);
 427
 428         mutex_lock(&nf_ct_proto_mutex);
 429         BUG_ON(rcu_dereference_protected(
 430                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 431                         lockdep_is_held(&nf_ct_proto_mutex)
 432                         ) != l4proto);
 433         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 434                            &nf_conntrack_l4proto_generic);
 435         mutex_unlock(&nf_ct_proto_mutex);
 436
 437         synchronize_rcu();
 438 }
 439 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
 440
 441 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 442                                          struct nf_conntrack_l4proto *l4proto)
 443 {
 444         struct nf_proto_net *pn = NULL;
 445
 446         pn = nf_ct_l4proto_net(net, l4proto);
 447         if (pn == NULL)
 448                 return;
 449
 450         pn->users--;
 451         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 452
 453         /* Remove all contrack entries for this protocol */
 454         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
 455 }
 456 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
 457
 458 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 459                            unsigned int num_proto)
 460 {
 461         int ret = -EINVAL, ver;
 462         unsigned int i;
 463
 464         for (i = 0; i < num_proto; i++) {
 465                 ret = nf_ct_l4proto_register_one(l4proto[i]);
 466                 if (ret < 0)
 467                         break;
 468         }
 469         if (i != num_proto) {
 470                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 471                 pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
 472                        ver, l4proto[i]->name, ver);
 473                 nf_ct_l4proto_unregister(l4proto, i);
 474         }
 475         return ret;
 476 }
 477 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 478
 479 int nf_ct_l4proto_pernet_register(struct net *net,
 480                                   struct nf_conntrack_l4proto *l4proto[],
 481                                   unsigned int num_proto)
 482 {
 483         int ret = -EINVAL;
 484         unsigned int i;
 485
 486         for (i = 0; i < num_proto; i++) {
 487                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 488                 if (ret < 0)
 489                         break;
 490         }
 491         if (i != num_proto) {
 492                 pr_err("nf_conntrack_%s%d: pernet registration failed\n",
 493                        l4proto[i]->name,
 494                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 495                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 496         }
 497         return ret;
 498 }
 499 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 500
 501 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 502                               unsigned int num_proto)
 503 {
 504         while (num_proto-- != 0)
 505                 nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 506 }
 507 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 508
 509 void nf_ct_l4proto_pernet_unregister(struct net *net,
 510                                      struct nf_conntrack_l4proto *l4proto[],
 511                                      unsigned int num_proto)
 512 {
 513         while (num_proto-- != 0)
 514                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 515 }
 516 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 517
 518 int nf_conntrack_proto_pernet_init(struct net *net)
 519 {
 520         int err;
 521         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 522                                         &nf_conntrack_l4proto_generic);
 523
 524         err = nf_conntrack_l4proto_generic.init_net(net,
 525                                         nf_conntrack_l4proto_generic.l3proto);
 526         if (err < 0)
 527                 return err;
 528         err = nf_ct_l4proto_register_sysctl(net,
 529                                             pn,
 530                                             &nf_conntrack_l4proto_generic);
 531         if (err < 0)
 532                 return err;
 533
 534         pn->users++;
 535         return 0;
 536 }
 537
 538 void nf_conntrack_proto_pernet_fini(struct net *net)
 539 {
 540         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 541                                         &nf_conntrack_l4proto_generic);
 542
 543         pn->users--;
 544         nf_ct_l4proto_unregister_sysctl(net,
 545                                         pn,
 546                                         &nf_conntrack_l4proto_generic);
 547 }
 548
 549 int nf_conntrack_proto_init(void)
 550 {
 551         unsigned int i;
 552         for (i = 0; i < AF_MAX; i++)
 553                 rcu_assign_pointer(nf_ct_l3protos[i],
 554                                    &nf_conntrack_l3proto_generic);
 555         return 0;
 556 }
 557
 558 void nf_conntrack_proto_fini(void)
 559 {
 560         unsigned int i;
 561         /* free l3proto protocol tables */
 562         for (i = 0; i < PF_MAX; i++)
 563                 kfree(nf_ct_protos[i]);
 564 }