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 const 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 const 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         const struct nf_conntrack_l3proto *p;
  99         int ret;
 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 const struct nf_conntrack_l4proto *
 177 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 178 {
 179         const 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(const 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) == ((const struct nf_conntrack_l3proto *)data)->l3proto;
 200 }
 201
 202 static int kill_l4proto(struct nf_conn *i, void *data)
 203 {
 204         const 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(const 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 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 218         if (proto->tuple_to_nlattr && proto->nla_size == 0)
 219                 return -EINVAL;
 220 #endif
 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         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 230
 231 out_unlock:
 232         mutex_unlock(&nf_ct_proto_mutex);
 233         return ret;
 234
 235 }
 236 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 237
 238 void nf_ct_l3proto_unregister(const struct nf_conntrack_l3proto *proto)
 239 {
 240         BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);
 241
 242         mutex_lock(&nf_ct_proto_mutex);
 243         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 244                                          lockdep_is_held(&nf_ct_proto_mutex)
 245                                          ) != proto);
 246         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 247                            &nf_conntrack_l3proto_generic);
 248         mutex_unlock(&nf_ct_proto_mutex);
 249
 250         synchronize_rcu();
 251         /* Remove all contrack entries for this protocol */
 252         nf_ct_iterate_destroy(kill_l3proto, (void*)proto);
 253 }
 254 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 255
 256 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 257                                 const struct nf_conntrack_l4proto *l4proto)
 258 {
 259         if (l4proto->get_net_proto) {
 260                 /* statically built-in protocols use static per-net */
 261                 return l4proto->get_net_proto(net);
 262         } else if (l4proto->net_id) {
 263                 /* ... and loadable protocols use dynamic per-net */
 264                 return net_generic(net, *l4proto->net_id);
 265         }
 266         return NULL;
 267 }
 268
 269 static
 270 int nf_ct_l4proto_register_sysctl(struct net *net,
 271                                   struct nf_proto_net *pn,
 272                                   const struct nf_conntrack_l4proto *l4proto)
 273 {
 274         int err = 0;
 275
 276 #ifdef CONFIG_SYSCTL
 277         if (pn->ctl_table != NULL) {
 278                 err = nf_ct_register_sysctl(net,
 279                                             &pn->ctl_table_header,
 280                                             "net/netfilter",
 281                                             pn->ctl_table);
 282                 if (err < 0) {
 283                         if (!pn->users) {
 284                                 kfree(pn->ctl_table);
 285                                 pn->ctl_table = NULL;
 286                         }
 287                 }
 288         }
 289 #endif /* CONFIG_SYSCTL */
 290         return err;
 291 }
 292
 293 static
 294 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 295                                 struct nf_proto_net *pn,
 296                                 const struct nf_conntrack_l4proto *l4proto)
 297 {
 298 #ifdef CONFIG_SYSCTL
 299         if (pn->ctl_table_header != NULL)
 300                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 301                                         &pn->ctl_table,
 302                                         pn->users);
 303 #endif /* CONFIG_SYSCTL */
 304 }
 305
 306 /* FIXME: Allow NULL functions and sub in pointers to generic for
 307    them. --RR */
 308 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 309 {
 310         int ret = 0;
 311
 312         if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
 313                 return -EBUSY;
 314
 315         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 316             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 317                 return -EINVAL;
 318
 319         mutex_lock(&nf_ct_proto_mutex);
 320         if (!nf_ct_protos[l4proto->l3proto]) {
 321                 /* l3proto may be loaded latter. */
 322                 struct nf_conntrack_l4proto __rcu **proto_array;
 323                 int i;
 324
 325                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 326                                       sizeof(struct nf_conntrack_l4proto *),
 327                                       GFP_KERNEL);
 328                 if (proto_array == NULL) {
 329                         ret = -ENOMEM;
 330                         goto out_unlock;
 331                 }
 332
 333                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 334                         RCU_INIT_POINTER(proto_array[i],
 335                                          &nf_conntrack_l4proto_generic);
 336
 337                 /* Before making proto_array visible to lockless readers,
 338                  * we must make sure its content is committed to memory.
 339                  */
 340                 smp_wmb();
 341
 342                 nf_ct_protos[l4proto->l3proto] = proto_array;
 343         } else if (rcu_dereference_protected(
 344                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 345                         lockdep_is_held(&nf_ct_proto_mutex)
 346                         ) != &nf_conntrack_l4proto_generic) {
 347                 ret = -EBUSY;
 348                 goto out_unlock;
 349         }
 350
 351         l4proto->nla_size = 0;
 352         if (l4proto->nlattr_size)
 353                 l4proto->nla_size += l4proto->nlattr_size();
 354         if (l4proto->nlattr_tuple_size)
 355                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 356
 357         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 358                            l4proto);
 359 out_unlock:
 360         mutex_unlock(&nf_ct_proto_mutex);
 361         return ret;
 362 }
 363 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
 364
 365 int nf_ct_l4proto_pernet_register_one(struct net *net,
 366                                 const struct nf_conntrack_l4proto *l4proto)
 367 {
 368         int ret = 0;
 369         struct nf_proto_net *pn = NULL;
 370
 371         if (l4proto->init_net) {
 372                 ret = l4proto->init_net(net, l4proto->l3proto);
 373                 if (ret < 0)
 374                         goto out;
 375         }
 376
 377         pn = nf_ct_l4proto_net(net, l4proto);
 378         if (pn == NULL)
 379                 goto out;
 380
 381         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 382         if (ret < 0)
 383                 goto out;
 384
 385         pn->users++;
 386 out:
 387         return ret;
 388 }
 389 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
 390
 391 static void __nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
 392
 393 {
 394         BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));
 395
 396         BUG_ON(rcu_dereference_protected(
 397                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 398                         lockdep_is_held(&nf_ct_proto_mutex)
 399                         ) != l4proto);
 400         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 401                            &nf_conntrack_l4proto_generic);
 402 }
 403
 404 void nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
 405 {
 406         mutex_lock(&nf_ct_proto_mutex);
 407         __nf_ct_l4proto_unregister_one(l4proto);
 408         mutex_unlock(&nf_ct_proto_mutex);
 409
 410         synchronize_rcu();
 411 }
 412 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
 413
 414 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 415                                 const struct nf_conntrack_l4proto *l4proto)
 416 {
 417         struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
 418
 419         if (pn == NULL)
 420                 return;
 421
 422         pn->users--;
 423         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 424 }
 425 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
 426
 427 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 428                            unsigned int num_proto)
 429 {
 430         int ret = -EINVAL, ver;
 431         unsigned int i;
 432
 433         for (i = 0; i < num_proto; i++) {
 434                 ret = nf_ct_l4proto_register_one(l4proto[i]);
 435                 if (ret < 0)
 436                         break;
 437         }
 438         if (i != num_proto) {
 439                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 440                 pr_err("nf_conntrack_ipv%d: can't register l4 %d proto.\n",
 441                        ver, l4proto[i]->l4proto);
 442                 nf_ct_l4proto_unregister(l4proto, i);
 443         }
 444         return ret;
 445 }
 446 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 447
 448 int nf_ct_l4proto_pernet_register(struct net *net,
 449                                   struct nf_conntrack_l4proto *const l4proto[],
 450                                   unsigned int num_proto)
 451 {
 452         int ret = -EINVAL;
 453         unsigned int i;
 454
 455         for (i = 0; i < num_proto; i++) {
 456                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 457                 if (ret < 0)
 458                         break;
 459         }
 460         if (i != num_proto) {
 461                 pr_err("nf_conntrack_proto_%d %d: pernet registration failed\n",
 462                        l4proto[i]->l4proto,
 463                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 464                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 465         }
 466         return ret;
 467 }
 468 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 469
 470 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 471                               unsigned int num_proto)
 472 {
 473         mutex_lock(&nf_ct_proto_mutex);
 474         while (num_proto-- != 0)
 475                 __nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 476         mutex_unlock(&nf_ct_proto_mutex);
 477
 478         synchronize_net();
 479         /* Remove all contrack entries for this protocol */
 480         nf_ct_iterate_destroy(kill_l4proto, l4proto);
 481 }
 482 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 483
 484 void nf_ct_l4proto_pernet_unregister(struct net *net,
 485                                 struct nf_conntrack_l4proto *const l4proto[],
 486                                 unsigned int num_proto)
 487 {
 488         while (num_proto-- != 0)
 489                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 490 }
 491 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 492
 493 int nf_conntrack_proto_pernet_init(struct net *net)
 494 {
 495         int err;
 496         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 497                                         &nf_conntrack_l4proto_generic);
 498
 499         err = nf_conntrack_l4proto_generic.init_net(net,
 500                                         nf_conntrack_l4proto_generic.l3proto);
 501         if (err < 0)
 502                 return err;
 503         err = nf_ct_l4proto_register_sysctl(net,
 504                                             pn,
 505                                             &nf_conntrack_l4proto_generic);
 506         if (err < 0)
 507                 return err;
 508
 509         pn->users++;
 510         return 0;
 511 }
 512
 513 void nf_conntrack_proto_pernet_fini(struct net *net)
 514 {
 515         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 516                                         &nf_conntrack_l4proto_generic);
 517
 518         pn->users--;
 519         nf_ct_l4proto_unregister_sysctl(net,
 520                                         pn,
 521                                         &nf_conntrack_l4proto_generic);
 522 }
 523
 524 int nf_conntrack_proto_init(void)
 525 {
 526         unsigned int i;
 527         for (i = 0; i < NFPROTO_NUMPROTO; i++)
 528                 rcu_assign_pointer(nf_ct_l3protos[i],
 529                                    &nf_conntrack_l3proto_generic);
 530         return 0;
 531 }
 532
 533 void nf_conntrack_proto_fini(void)
 534 {
 535         unsigned int i;
 536         /* free l3proto protocol tables */
 537         for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
 538                 kfree(nf_ct_protos[i]);
 539 }