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 <coreteam@netfilter.org>
   5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   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[NFPROTO_NUMPROTO] __read_mostly;
  32 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __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 >= NFPROTO_NUMPROTO || 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 = 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 >= NFPROTO_NUMPROTO)
 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 >= NFPROTO_NUMPROTO);
 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         /* Remove all contrack entries for this protocol */
 269         nf_ct_iterate_destroy(kill_l3proto, proto);
 270 }
 271 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 272
 273 void nf_ct_l3proto_pernet_unregister(struct net *net,
 274                                      struct nf_conntrack_l3proto *proto)
 275 {
 276         /*
 277          * nf_conntrack_default_on *might* have registered hooks.
 278          * ->net_ns_put must cope with more puts() than get(), i.e.
 279          * if nf_conntrack_default_on was 0 at time of
 280          * nf_ct_l3proto_pernet_register invocation this net_ns_put()
 281          * should be a noop.
 282          */
 283         if (proto->net_ns_put)
 284                 proto->net_ns_put(net);
 285 }
 286 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
 287
 288 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 289                                               struct nf_conntrack_l4proto *l4proto)
 290 {
 291         if (l4proto->get_net_proto) {
 292                 /* statically built-in protocols use static per-net */
 293                 return l4proto->get_net_proto(net);
 294         } else if (l4proto->net_id) {
 295                 /* ... and loadable protocols use dynamic per-net */
 296                 return net_generic(net, *l4proto->net_id);
 297         }
 298         return NULL;
 299 }
 300
 301 static
 302 int nf_ct_l4proto_register_sysctl(struct net *net,
 303                                   struct nf_proto_net *pn,
 304                                   struct nf_conntrack_l4proto *l4proto)
 305 {
 306         int err = 0;
 307
 308 #ifdef CONFIG_SYSCTL
 309         if (pn->ctl_table != NULL) {
 310                 err = nf_ct_register_sysctl(net,
 311                                             &pn->ctl_table_header,
 312                                             "net/netfilter",
 313                                             pn->ctl_table);
 314                 if (err < 0) {
 315                         if (!pn->users) {
 316                                 kfree(pn->ctl_table);
 317                                 pn->ctl_table = NULL;
 318                         }
 319                 }
 320         }
 321 #endif /* CONFIG_SYSCTL */
 322         return err;
 323 }
 324
 325 static
 326 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 327                                      struct nf_proto_net *pn,
 328                                      struct nf_conntrack_l4proto *l4proto)
 329 {
 330 #ifdef CONFIG_SYSCTL
 331         if (pn->ctl_table_header != NULL)
 332                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 333                                         &pn->ctl_table,
 334                                         pn->users);
 335 #endif /* CONFIG_SYSCTL */
 336 }
 337
 338 /* FIXME: Allow NULL functions and sub in pointers to generic for
 339    them. --RR */
 340 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 341 {
 342         int ret = 0;
 343
 344         if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
 345                 return -EBUSY;
 346
 347         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 348             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 349                 return -EINVAL;
 350
 351         mutex_lock(&nf_ct_proto_mutex);
 352         if (!nf_ct_protos[l4proto->l3proto]) {
 353                 /* l3proto may be loaded latter. */
 354                 struct nf_conntrack_l4proto __rcu **proto_array;
 355                 int i;
 356
 357                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 358                                       sizeof(struct nf_conntrack_l4proto *),
 359                                       GFP_KERNEL);
 360                 if (proto_array == NULL) {
 361                         ret = -ENOMEM;
 362                         goto out_unlock;
 363                 }
 364
 365                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 366                         RCU_INIT_POINTER(proto_array[i],
 367                                          &nf_conntrack_l4proto_generic);
 368
 369                 /* Before making proto_array visible to lockless readers,
 370                  * we must make sure its content is committed to memory.
 371                  */
 372                 smp_wmb();
 373
 374                 nf_ct_protos[l4proto->l3proto] = proto_array;
 375         } else if (rcu_dereference_protected(
 376                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 377                         lockdep_is_held(&nf_ct_proto_mutex)
 378                         ) != &nf_conntrack_l4proto_generic) {
 379                 ret = -EBUSY;
 380                 goto out_unlock;
 381         }
 382
 383         l4proto->nla_size = 0;
 384         if (l4proto->nlattr_size)
 385                 l4proto->nla_size += l4proto->nlattr_size();
 386         if (l4proto->nlattr_tuple_size)
 387                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 388
 389         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 390                            l4proto);
 391 out_unlock:
 392         mutex_unlock(&nf_ct_proto_mutex);
 393         return ret;
 394 }
 395 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
 396
 397 int nf_ct_l4proto_pernet_register_one(struct net *net,
 398                                       struct nf_conntrack_l4proto *l4proto)
 399 {
 400         int ret = 0;
 401         struct nf_proto_net *pn = NULL;
 402
 403         if (l4proto->init_net) {
 404                 ret = l4proto->init_net(net, l4proto->l3proto);
 405                 if (ret < 0)
 406                         goto out;
 407         }
 408
 409         pn = nf_ct_l4proto_net(net, l4proto);
 410         if (pn == NULL)
 411                 goto out;
 412
 413         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 414         if (ret < 0)
 415                 goto out;
 416
 417         pn->users++;
 418 out:
 419         return ret;
 420 }
 421 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
 422
 423 static void __nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
 424
 425 {
 426         BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));
 427
 428         BUG_ON(rcu_dereference_protected(
 429                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 430                         lockdep_is_held(&nf_ct_proto_mutex)
 431                         ) != l4proto);
 432         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 433                            &nf_conntrack_l4proto_generic);
 434 }
 435
 436 void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
 437 {
 438         mutex_lock(&nf_ct_proto_mutex);
 439         __nf_ct_l4proto_unregister_one(l4proto);
 440         mutex_unlock(&nf_ct_proto_mutex);
 441
 442         synchronize_rcu();
 443 }
 444 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
 445
 446 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 447                                          struct nf_conntrack_l4proto *l4proto)
 448 {
 449         struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
 450
 451         if (pn == NULL)
 452                 return;
 453
 454         pn->users--;
 455         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 456 }
 457 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
 458
 459 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 460                            unsigned int num_proto)
 461 {
 462         int ret = -EINVAL, ver;
 463         unsigned int i;
 464
 465         for (i = 0; i < num_proto; i++) {
 466                 ret = nf_ct_l4proto_register_one(l4proto[i]);
 467                 if (ret < 0)
 468                         break;
 469         }
 470         if (i != num_proto) {
 471                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 472                 pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
 473                        ver, l4proto[i]->name, ver);
 474                 nf_ct_l4proto_unregister(l4proto, i);
 475         }
 476         return ret;
 477 }
 478 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 479
 480 int nf_ct_l4proto_pernet_register(struct net *net,
 481                                   struct nf_conntrack_l4proto *l4proto[],
 482                                   unsigned int num_proto)
 483 {
 484         int ret = -EINVAL;
 485         unsigned int i;
 486
 487         for (i = 0; i < num_proto; i++) {
 488                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 489                 if (ret < 0)
 490                         break;
 491         }
 492         if (i != num_proto) {
 493                 pr_err("nf_conntrack_%s%d: pernet registration failed\n",
 494                        l4proto[i]->name,
 495                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 496                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 497         }
 498         return ret;
 499 }
 500 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 501
 502 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 503                               unsigned int num_proto)
 504 {
 505         mutex_lock(&nf_ct_proto_mutex);
 506         while (num_proto-- != 0)
 507                 __nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 508         mutex_unlock(&nf_ct_proto_mutex);
 509
 510         synchronize_net();
 511         /* Remove all contrack entries for this protocol */
 512         nf_ct_iterate_destroy(kill_l4proto, l4proto);
 513 }
 514 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 515
 516 void nf_ct_l4proto_pernet_unregister(struct net *net,
 517                                      struct nf_conntrack_l4proto *l4proto[],
 518                                      unsigned int num_proto)
 519 {
 520         while (num_proto-- != 0)
 521                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 522 }
 523 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 524
 525 int nf_conntrack_proto_pernet_init(struct net *net)
 526 {
 527         int err;
 528         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 529                                         &nf_conntrack_l4proto_generic);
 530
 531         err = nf_conntrack_l4proto_generic.init_net(net,
 532                                         nf_conntrack_l4proto_generic.l3proto);
 533         if (err < 0)
 534                 return err;
 535         err = nf_ct_l4proto_register_sysctl(net,
 536                                             pn,
 537                                             &nf_conntrack_l4proto_generic);
 538         if (err < 0)
 539                 return err;
 540
 541         pn->users++;
 542         return 0;
 543 }
 544
 545 void nf_conntrack_proto_pernet_fini(struct net *net)
 546 {
 547         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 548                                         &nf_conntrack_l4proto_generic);
 549
 550         pn->users--;
 551         nf_ct_l4proto_unregister_sysctl(net,
 552                                         pn,
 553                                         &nf_conntrack_l4proto_generic);
 554 }
 555
 556 int nf_conntrack_proto_init(void)
 557 {
 558         unsigned int i;
 559         for (i = 0; i < NFPROTO_NUMPROTO; i++)
 560                 rcu_assign_pointer(nf_ct_l3protos[i],
 561                                    &nf_conntrack_l3proto_generic);
 562         return 0;
 563 }
 564
 565 void nf_conntrack_proto_fini(void)
 566 {
 567         unsigned int i;
 568         /* free l3proto protocol tables */
 569         for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
 570                 kfree(nf_ct_protos[i]);
 571 }