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 #include <net/netfilter/nf_log.h>
  31
  32 static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
  33 struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __read_mostly;
  34 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
  35
  36 static DEFINE_MUTEX(nf_ct_proto_mutex);
  37
  38 #ifdef CONFIG_SYSCTL
  39 static int
  40 nf_ct_register_sysctl(struct net *net,
  41                       struct ctl_table_header **header,
  42                       const char *path,
  43                       struct ctl_table *table)
  44 {
  45         if (*header == NULL) {
  46                 *header = register_net_sysctl(net, path, table);
  47                 if (*header == NULL)
  48                         return -ENOMEM;
  49         }
  50
  51         return 0;
  52 }
  53
  54 static void
  55 nf_ct_unregister_sysctl(struct ctl_table_header **header,
  56                         struct ctl_table **table,
  57                         unsigned int users)
  58 {
  59         if (users > 0)
  60                 return;
  61
  62         unregister_net_sysctl_table(*header);
  63         kfree(*table);
  64         *header = NULL;
  65         *table = NULL;
  66 }
  67
  68 __printf(5, 6)
  69 void nf_l4proto_log_invalid(const struct sk_buff *skb,
  70                             struct net *net,
  71                             u16 pf, u8 protonum,
  72                             const char *fmt, ...)
  73 {
  74         struct va_format vaf;
  75         va_list args;
  76
  77         if (net->ct.sysctl_log_invalid != protonum ||
  78             net->ct.sysctl_log_invalid != IPPROTO_RAW)
  79                 return;
  80
  81         va_start(args, fmt);
  82         vaf.fmt = fmt;
  83         vaf.va = &args;
  84
  85         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
  86                       "nf_ct_proto_%d: %pV ", protonum, &vaf);
  87         va_end(args);
  88 }
  89 EXPORT_SYMBOL_GPL(nf_l4proto_log_invalid);
  90
  91 __printf(3, 4)
  92 void nf_ct_l4proto_log_invalid(const struct sk_buff *skb,
  93                                const struct nf_conn *ct,
  94                                const char *fmt, ...)
  95 {
  96         struct va_format vaf;
  97         struct net *net;
  98         va_list args;
  99
 100         net = nf_ct_net(ct);
 101         if (likely(net->ct.sysctl_log_invalid == 0))
 102                 return;
 103
 104         va_start(args, fmt);
 105         vaf.fmt = fmt;
 106         vaf.va = &args;
 107
 108         nf_l4proto_log_invalid(skb, net, nf_ct_l3num(ct),
 109                                nf_ct_protonum(ct), "%pV", &vaf);
 110         va_end(args);
 111 }
 112 EXPORT_SYMBOL_GPL(nf_ct_l4proto_log_invalid);
 113 #endif
 114
 115 const struct nf_conntrack_l4proto *
 116 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
 117 {
 118         if (unlikely(l3proto >= NFPROTO_NUMPROTO || nf_ct_protos[l3proto] == NULL))
 119                 return &nf_conntrack_l4proto_generic;
 120
 121         return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
 122 }
 123 EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
 124
 125 /* this is guaranteed to always return a valid protocol helper, since
 126  * it falls back to generic_protocol */
 127 const struct nf_conntrack_l3proto *
 128 nf_ct_l3proto_find_get(u_int16_t l3proto)
 129 {
 130         struct nf_conntrack_l3proto *p;
 131
 132         rcu_read_lock();
 133         p = __nf_ct_l3proto_find(l3proto);
 134         if (!try_module_get(p->me))
 135                 p = &nf_conntrack_l3proto_generic;
 136         rcu_read_unlock();
 137
 138         return p;
 139 }
 140 EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
 141
 142 int
 143 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 144 {
 145         const struct nf_conntrack_l3proto *p;
 146         int ret;
 147
 148 retry:  p = nf_ct_l3proto_find_get(l3proto);
 149         if (p == &nf_conntrack_l3proto_generic) {
 150                 ret = request_module("nf_conntrack-%d", l3proto);
 151                 if (!ret)
 152                         goto retry;
 153
 154                 return -EPROTOTYPE;
 155         }
 156
 157         return 0;
 158 }
 159 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 160
 161 void nf_ct_l3proto_module_put(unsigned short l3proto)
 162 {
 163         struct nf_conntrack_l3proto *p;
 164
 165         /* rcu_read_lock not necessary since the caller holds a reference, but
 166          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 167          */
 168         rcu_read_lock();
 169         p = __nf_ct_l3proto_find(l3proto);
 170         module_put(p->me);
 171         rcu_read_unlock();
 172 }
 173 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 174
 175 static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
 176 {
 177         const struct nf_conntrack_l3proto *l3proto;
 178         int ret;
 179
 180         might_sleep();
 181
 182         ret = nf_ct_l3proto_try_module_get(nfproto);
 183         if (ret < 0)
 184                 return ret;
 185
 186         /* we already have a reference, can't fail */
 187         rcu_read_lock();
 188         l3proto = __nf_ct_l3proto_find(nfproto);
 189         rcu_read_unlock();
 190
 191         if (!l3proto->net_ns_get)
 192                 return 0;
 193
 194         ret = l3proto->net_ns_get(net);
 195         if (ret < 0)
 196                 nf_ct_l3proto_module_put(nfproto);
 197
 198         return ret;
 199 }
 200
 201 int nf_ct_netns_get(struct net *net, u8 nfproto)
 202 {
 203         int err;
 204
 205         if (nfproto == NFPROTO_INET) {
 206                 err = nf_ct_netns_do_get(net, NFPROTO_IPV4);
 207                 if (err < 0)
 208                         goto err1;
 209                 err = nf_ct_netns_do_get(net, NFPROTO_IPV6);
 210                 if (err < 0)
 211                         goto err2;
 212         } else {
 213                 err = nf_ct_netns_do_get(net, nfproto);
 214                 if (err < 0)
 215                         goto err1;
 216         }
 217         return 0;
 218
 219 err2:
 220         nf_ct_netns_put(net, NFPROTO_IPV4);
 221 err1:
 222         return err;
 223 }
 224 EXPORT_SYMBOL_GPL(nf_ct_netns_get);
 225
 226 static void nf_ct_netns_do_put(struct net *net, u8 nfproto)
 227 {
 228         const struct nf_conntrack_l3proto *l3proto;
 229
 230         might_sleep();
 231
 232         /* same as nf_conntrack_netns_get(), reference assumed */
 233         rcu_read_lock();
 234         l3proto = __nf_ct_l3proto_find(nfproto);
 235         rcu_read_unlock();
 236
 237         if (WARN_ON(!l3proto))
 238                 return;
 239
 240         if (l3proto->net_ns_put)
 241                 l3proto->net_ns_put(net);
 242
 243         nf_ct_l3proto_module_put(nfproto);
 244 }
 245
 246 void nf_ct_netns_put(struct net *net, uint8_t nfproto)
 247 {
 248         if (nfproto == NFPROTO_INET) {
 249                 nf_ct_netns_do_put(net, NFPROTO_IPV4);
 250                 nf_ct_netns_do_put(net, NFPROTO_IPV6);
 251         } else
 252                 nf_ct_netns_do_put(net, nfproto);
 253 }
 254 EXPORT_SYMBOL_GPL(nf_ct_netns_put);
 255
 256 const struct nf_conntrack_l4proto *
 257 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 258 {
 259         const struct nf_conntrack_l4proto *p;
 260
 261         rcu_read_lock();
 262         p = __nf_ct_l4proto_find(l3num, l4num);
 263         if (!try_module_get(p->me))
 264                 p = &nf_conntrack_l4proto_generic;
 265         rcu_read_unlock();
 266
 267         return p;
 268 }
 269 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
 270
 271 void nf_ct_l4proto_put(const struct nf_conntrack_l4proto *p)
 272 {
 273         module_put(p->me);
 274 }
 275 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
 276
 277 static int kill_l3proto(struct nf_conn *i, void *data)
 278 {
 279         return nf_ct_l3num(i) == ((const struct nf_conntrack_l3proto *)data)->l3proto;
 280 }
 281
 282 static int kill_l4proto(struct nf_conn *i, void *data)
 283 {
 284         const struct nf_conntrack_l4proto *l4proto;
 285         l4proto = data;
 286         return nf_ct_protonum(i) == l4proto->l4proto &&
 287                nf_ct_l3num(i) == l4proto->l3proto;
 288 }
 289
 290 int nf_ct_l3proto_register(const struct nf_conntrack_l3proto *proto)
 291 {
 292         int ret = 0;
 293         struct nf_conntrack_l3proto *old;
 294
 295         if (proto->l3proto >= NFPROTO_NUMPROTO)
 296                 return -EBUSY;
 297 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 298         if (proto->tuple_to_nlattr && proto->nla_size == 0)
 299                 return -EINVAL;
 300 #endif
 301         mutex_lock(&nf_ct_proto_mutex);
 302         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 303                                         lockdep_is_held(&nf_ct_proto_mutex));
 304         if (old != &nf_conntrack_l3proto_generic) {
 305                 ret = -EBUSY;
 306                 goto out_unlock;
 307         }
 308
 309         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 310
 311 out_unlock:
 312         mutex_unlock(&nf_ct_proto_mutex);
 313         return ret;
 314
 315 }
 316 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 317
 318 void nf_ct_l3proto_unregister(const struct nf_conntrack_l3proto *proto)
 319 {
 320         BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);
 321
 322         mutex_lock(&nf_ct_proto_mutex);
 323         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 324                                          lockdep_is_held(&nf_ct_proto_mutex)
 325                                          ) != proto);
 326         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 327                            &nf_conntrack_l3proto_generic);
 328         mutex_unlock(&nf_ct_proto_mutex);
 329
 330         synchronize_rcu();
 331         /* Remove all contrack entries for this protocol */
 332         nf_ct_iterate_destroy(kill_l3proto, (void*)proto);
 333 }
 334 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 335
 336 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 337                                 const struct nf_conntrack_l4proto *l4proto)
 338 {
 339         if (l4proto->get_net_proto) {
 340                 /* statically built-in protocols use static per-net */
 341                 return l4proto->get_net_proto(net);
 342         } else if (l4proto->net_id) {
 343                 /* ... and loadable protocols use dynamic per-net */
 344                 return net_generic(net, *l4proto->net_id);
 345         }
 346         return NULL;
 347 }
 348
 349 static
 350 int nf_ct_l4proto_register_sysctl(struct net *net,
 351                                   struct nf_proto_net *pn,
 352                                   const struct nf_conntrack_l4proto *l4proto)
 353 {
 354         int err = 0;
 355
 356 #ifdef CONFIG_SYSCTL
 357         if (pn->ctl_table != NULL) {
 358                 err = nf_ct_register_sysctl(net,
 359                                             &pn->ctl_table_header,
 360                                             "net/netfilter",
 361                                             pn->ctl_table);
 362                 if (err < 0) {
 363                         if (!pn->users) {
 364                                 kfree(pn->ctl_table);
 365                                 pn->ctl_table = NULL;
 366                         }
 367                 }
 368         }
 369 #endif /* CONFIG_SYSCTL */
 370         return err;
 371 }
 372
 373 static
 374 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 375                                 struct nf_proto_net *pn,
 376                                 const struct nf_conntrack_l4proto *l4proto)
 377 {
 378 #ifdef CONFIG_SYSCTL
 379         if (pn->ctl_table_header != NULL)
 380                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 381                                         &pn->ctl_table,
 382                                         pn->users);
 383 #endif /* CONFIG_SYSCTL */
 384 }
 385
 386 /* FIXME: Allow NULL functions and sub in pointers to generic for
 387    them. --RR */
 388 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 389 {
 390         int ret = 0;
 391
 392         if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
 393                 return -EBUSY;
 394
 395         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 396             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 397                 return -EINVAL;
 398
 399         mutex_lock(&nf_ct_proto_mutex);
 400         if (!nf_ct_protos[l4proto->l3proto]) {
 401                 /* l3proto may be loaded latter. */
 402                 struct nf_conntrack_l4proto __rcu **proto_array;
 403                 int i;
 404
 405                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 406                                       sizeof(struct nf_conntrack_l4proto *),
 407                                       GFP_KERNEL);
 408                 if (proto_array == NULL) {
 409                         ret = -ENOMEM;
 410                         goto out_unlock;
 411                 }
 412
 413                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 414                         RCU_INIT_POINTER(proto_array[i],
 415                                          &nf_conntrack_l4proto_generic);
 416
 417                 /* Before making proto_array visible to lockless readers,
 418                  * we must make sure its content is committed to memory.
 419                  */
 420                 smp_wmb();
 421
 422                 nf_ct_protos[l4proto->l3proto] = proto_array;
 423         } else if (rcu_dereference_protected(
 424                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 425                         lockdep_is_held(&nf_ct_proto_mutex)
 426                         ) != &nf_conntrack_l4proto_generic) {
 427                 ret = -EBUSY;
 428                 goto out_unlock;
 429         }
 430
 431         l4proto->nla_size = 0;
 432         if (l4proto->nlattr_size)
 433                 l4proto->nla_size += l4proto->nlattr_size();
 434
 435         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 436                            l4proto);
 437 out_unlock:
 438         mutex_unlock(&nf_ct_proto_mutex);
 439         return ret;
 440 }
 441 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
 442
 443 int nf_ct_l4proto_pernet_register_one(struct net *net,
 444                                 const struct nf_conntrack_l4proto *l4proto)
 445 {
 446         int ret = 0;
 447         struct nf_proto_net *pn = NULL;
 448
 449         if (l4proto->init_net) {
 450                 ret = l4proto->init_net(net, l4proto->l3proto);
 451                 if (ret < 0)
 452                         goto out;
 453         }
 454
 455         pn = nf_ct_l4proto_net(net, l4proto);
 456         if (pn == NULL)
 457                 goto out;
 458
 459         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 460         if (ret < 0)
 461                 goto out;
 462
 463         pn->users++;
 464 out:
 465         return ret;
 466 }
 467 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
 468
 469 static void __nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
 470
 471 {
 472         BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));
 473
 474         BUG_ON(rcu_dereference_protected(
 475                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 476                         lockdep_is_held(&nf_ct_proto_mutex)
 477                         ) != l4proto);
 478         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 479                            &nf_conntrack_l4proto_generic);
 480 }
 481
 482 void nf_ct_l4proto_unregister_one(const struct nf_conntrack_l4proto *l4proto)
 483 {
 484         mutex_lock(&nf_ct_proto_mutex);
 485         __nf_ct_l4proto_unregister_one(l4proto);
 486         mutex_unlock(&nf_ct_proto_mutex);
 487
 488         synchronize_rcu();
 489 }
 490 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
 491
 492 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 493                                 const struct nf_conntrack_l4proto *l4proto)
 494 {
 495         struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
 496
 497         if (pn == NULL)
 498                 return;
 499
 500         pn->users--;
 501         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 502 }
 503 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
 504
 505 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 506                            unsigned int num_proto)
 507 {
 508         int ret = -EINVAL, ver;
 509         unsigned int i;
 510
 511         for (i = 0; i < num_proto; i++) {
 512                 ret = nf_ct_l4proto_register_one(l4proto[i]);
 513                 if (ret < 0)
 514                         break;
 515         }
 516         if (i != num_proto) {
 517                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 518                 pr_err("nf_conntrack_ipv%d: can't register l4 %d proto.\n",
 519                        ver, l4proto[i]->l4proto);
 520                 nf_ct_l4proto_unregister(l4proto, i);
 521         }
 522         return ret;
 523 }
 524 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 525
 526 int nf_ct_l4proto_pernet_register(struct net *net,
 527                                   struct nf_conntrack_l4proto *const l4proto[],
 528                                   unsigned int num_proto)
 529 {
 530         int ret = -EINVAL;
 531         unsigned int i;
 532
 533         for (i = 0; i < num_proto; i++) {
 534                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 535                 if (ret < 0)
 536                         break;
 537         }
 538         if (i != num_proto) {
 539                 pr_err("nf_conntrack_proto_%d %d: pernet registration failed\n",
 540                        l4proto[i]->l4proto,
 541                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 542                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 543         }
 544         return ret;
 545 }
 546 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 547
 548 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 549                               unsigned int num_proto)
 550 {
 551         mutex_lock(&nf_ct_proto_mutex);
 552         while (num_proto-- != 0)
 553                 __nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 554         mutex_unlock(&nf_ct_proto_mutex);
 555
 556         synchronize_net();
 557         /* Remove all contrack entries for this protocol */
 558         nf_ct_iterate_destroy(kill_l4proto, l4proto);
 559 }
 560 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 561
 562 void nf_ct_l4proto_pernet_unregister(struct net *net,
 563                                 struct nf_conntrack_l4proto *const l4proto[],
 564                                 unsigned int num_proto)
 565 {
 566         while (num_proto-- != 0)
 567                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 568 }
 569 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 570
 571 int nf_conntrack_proto_pernet_init(struct net *net)
 572 {
 573         int err;
 574         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 575                                         &nf_conntrack_l4proto_generic);
 576
 577         err = nf_conntrack_l4proto_generic.init_net(net,
 578                                         nf_conntrack_l4proto_generic.l3proto);
 579         if (err < 0)
 580                 return err;
 581         err = nf_ct_l4proto_register_sysctl(net,
 582                                             pn,
 583                                             &nf_conntrack_l4proto_generic);
 584         if (err < 0)
 585                 return err;
 586
 587         pn->users++;
 588         return 0;
 589 }
 590
 591 void nf_conntrack_proto_pernet_fini(struct net *net)
 592 {
 593         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 594                                         &nf_conntrack_l4proto_generic);
 595
 596         pn->users--;
 597         nf_ct_l4proto_unregister_sysctl(net,
 598                                         pn,
 599                                         &nf_conntrack_l4proto_generic);
 600 }
 601
 602 int nf_conntrack_proto_init(void)
 603 {
 604         unsigned int i;
 605         for (i = 0; i < NFPROTO_NUMPROTO; i++)
 606                 rcu_assign_pointer(nf_ct_l3protos[i],
 607                                    &nf_conntrack_l3proto_generic);
 608         return 0;
 609 }
 610
 611 void nf_conntrack_proto_fini(void)
 612 {
 613         unsigned int i;
 614         /* free l3proto protocol tables */
 615         for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
 616                 kfree(nf_ct_protos[i]);
 617 }