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[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 struct nf_conntrack_l4proto *
 129 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 130 {
 131         struct nf_conntrack_l4proto *p;
 132
 133         rcu_read_lock();
 134         p = __nf_ct_l4proto_find(l3num, l4num);
 135         if (!try_module_get(p->me))
 136                 p = &nf_conntrack_l4proto_generic;
 137         rcu_read_unlock();
 138
 139         return p;
 140 }
 141 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
 142
 143 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
 144 {
 145         module_put(p->me);
 146 }
 147 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
 148
 149 static int kill_l3proto(struct nf_conn *i, void *data)
 150 {
 151         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 152 }
 153
 154 static int kill_l4proto(struct nf_conn *i, void *data)
 155 {
 156         struct nf_conntrack_l4proto *l4proto;
 157         l4proto = (struct nf_conntrack_l4proto *)data;
 158         return nf_ct_protonum(i) == l4proto->l4proto &&
 159                nf_ct_l3num(i) == l4proto->l3proto;
 160 }
 161
 162 static struct nf_ip_net *nf_ct_l3proto_net(struct net *net,
 163                                            struct nf_conntrack_l3proto *l3proto)
 164 {
 165         if (l3proto->l3proto == PF_INET)
 166                 return &net->ct.nf_ct_proto;
 167         else
 168                 return NULL;
 169 }
 170
 171 static int nf_ct_l3proto_register_sysctl(struct net *net,
 172                                          struct nf_conntrack_l3proto *l3proto)
 173 {
 174         int err = 0;
 175         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
 176         /* nf_conntrack_l3proto_ipv6 doesn't support sysctl */
 177         if (in == NULL)
 178                 return 0;
 179
 180 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 181         if (in->ctl_table != NULL) {
 182                 err = nf_ct_register_sysctl(net,
 183                                             &in->ctl_table_header,
 184                                             l3proto->ctl_table_path,
 185                                             in->ctl_table);
 186                 if (err < 0) {
 187                         kfree(in->ctl_table);
 188                         in->ctl_table = NULL;
 189                 }
 190         }
 191 #endif
 192         return err;
 193 }
 194
 195 static void nf_ct_l3proto_unregister_sysctl(struct net *net,
 196                                             struct nf_conntrack_l3proto *l3proto)
 197 {
 198         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
 199
 200         if (in == NULL)
 201                 return;
 202 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 203         if (in->ctl_table_header != NULL)
 204                 nf_ct_unregister_sysctl(&in->ctl_table_header,
 205                                         &in->ctl_table,
 206                                         0);
 207 #endif
 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 int nf_ct_l3proto_pernet_register(struct net *net,
 242                                   struct nf_conntrack_l3proto *proto)
 243 {
 244         int ret = 0;
 245
 246         if (proto->init_net) {
 247                 ret = proto->init_net(net);
 248                 if (ret < 0)
 249                         return ret;
 250         }
 251
 252         return nf_ct_l3proto_register_sysctl(net, proto);
 253 }
 254 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
 255
 256 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 257 {
 258         BUG_ON(proto->l3proto >= AF_MAX);
 259
 260         mutex_lock(&nf_ct_proto_mutex);
 261         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 262                                          lockdep_is_held(&nf_ct_proto_mutex)
 263                                          ) != proto);
 264         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 265                            &nf_conntrack_l3proto_generic);
 266         mutex_unlock(&nf_ct_proto_mutex);
 267
 268         synchronize_rcu();
 269 }
 270 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 271
 272 void nf_ct_l3proto_pernet_unregister(struct net *net,
 273                                      struct nf_conntrack_l3proto *proto)
 274 {
 275         nf_ct_l3proto_unregister_sysctl(net, proto);
 276
 277         /* Remove all contrack entries for this protocol */
 278         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 279 }
 280 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
 281
 282 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 283                                               struct nf_conntrack_l4proto *l4proto)
 284 {
 285         if (l4proto->get_net_proto) {
 286                 /* statically built-in protocols use static per-net */
 287                 return l4proto->get_net_proto(net);
 288         } else if (l4proto->net_id) {
 289                 /* ... and loadable protocols use dynamic per-net */
 290                 return net_generic(net, *l4proto->net_id);
 291         }
 292         return NULL;
 293 }
 294
 295 static
 296 int nf_ct_l4proto_register_sysctl(struct net *net,
 297                                   struct nf_proto_net *pn,
 298                                   struct nf_conntrack_l4proto *l4proto)
 299 {
 300         int err = 0;
 301
 302 #ifdef CONFIG_SYSCTL
 303         if (pn->ctl_table != NULL) {
 304                 err = nf_ct_register_sysctl(net,
 305                                             &pn->ctl_table_header,
 306                                             "net/netfilter",
 307                                             pn->ctl_table);
 308                 if (err < 0) {
 309                         if (!pn->users) {
 310                                 kfree(pn->ctl_table);
 311                                 pn->ctl_table = NULL;
 312                         }
 313                 }
 314         }
 315 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 316         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_table != NULL) {
 317                 if (err < 0) {
 318                         nf_ct_kfree_compat_sysctl_table(pn);
 319                         goto out;
 320                 }
 321                 err = nf_ct_register_sysctl(net,
 322                                             &pn->ctl_compat_header,
 323                                             "net/ipv4/netfilter",
 324                                             pn->ctl_compat_table);
 325                 if (err == 0)
 326                         goto out;
 327
 328                 nf_ct_kfree_compat_sysctl_table(pn);
 329                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 330                                         &pn->ctl_table,
 331                                         pn->users);
 332         }
 333 out:
 334 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 335 #endif /* CONFIG_SYSCTL */
 336         return err;
 337 }
 338
 339 static
 340 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 341                                      struct nf_proto_net *pn,
 342                                      struct nf_conntrack_l4proto *l4proto)
 343 {
 344 #ifdef CONFIG_SYSCTL
 345         if (pn->ctl_table_header != NULL)
 346                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 347                                         &pn->ctl_table,
 348                                         pn->users);
 349
 350 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 351         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
 352                 nf_ct_unregister_sysctl(&pn->ctl_compat_header,
 353                                         &pn->ctl_compat_table,
 354                                         0);
 355 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 356 #endif /* CONFIG_SYSCTL */
 357 }
 358
 359 /* FIXME: Allow NULL functions and sub in pointers to generic for
 360    them. --RR */
 361 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 362 {
 363         int ret = 0;
 364
 365         if (l4proto->l3proto >= PF_MAX)
 366                 return -EBUSY;
 367
 368         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 369                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 370                 return -EINVAL;
 371
 372         mutex_lock(&nf_ct_proto_mutex);
 373         if (!nf_ct_protos[l4proto->l3proto]) {
 374                 /* l3proto may be loaded latter. */
 375                 struct nf_conntrack_l4proto __rcu **proto_array;
 376                 int i;
 377
 378                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 379                                       sizeof(struct nf_conntrack_l4proto *),
 380                                       GFP_KERNEL);
 381                 if (proto_array == NULL) {
 382                         ret = -ENOMEM;
 383                         goto out_unlock;
 384                 }
 385
 386                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 387                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
 388
 389                 /* Before making proto_array visible to lockless readers,
 390                  * we must make sure its content is committed to memory.
 391                  */
 392                 smp_wmb();
 393
 394                 nf_ct_protos[l4proto->l3proto] = proto_array;
 395         } else if (rcu_dereference_protected(
 396                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 397                         lockdep_is_held(&nf_ct_proto_mutex)
 398                         ) != &nf_conntrack_l4proto_generic) {
 399                 ret = -EBUSY;
 400                 goto out_unlock;
 401         }
 402
 403         l4proto->nla_size = 0;
 404         if (l4proto->nlattr_size)
 405                 l4proto->nla_size += l4proto->nlattr_size();
 406         if (l4proto->nlattr_tuple_size)
 407                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 408
 409         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 410                            l4proto);
 411 out_unlock:
 412         mutex_unlock(&nf_ct_proto_mutex);
 413         return ret;
 414 }
 415 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 416
 417 int nf_ct_l4proto_pernet_register(struct net *net,
 418                                   struct nf_conntrack_l4proto *l4proto)
 419 {
 420         int ret = 0;
 421         struct nf_proto_net *pn = NULL;
 422
 423         if (l4proto->init_net) {
 424                 ret = l4proto->init_net(net, l4proto->l3proto);
 425                 if (ret < 0)
 426                         goto out;
 427         }
 428
 429         pn = nf_ct_l4proto_net(net, l4proto);
 430         if (pn == NULL)
 431                 goto out;
 432
 433         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 434         if (ret < 0)
 435                 goto out;
 436
 437         pn->users++;
 438 out:
 439         return ret;
 440 }
 441 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 442
 443 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 444 {
 445         BUG_ON(l4proto->l3proto >= PF_MAX);
 446
 447         mutex_lock(&nf_ct_proto_mutex);
 448         BUG_ON(rcu_dereference_protected(
 449                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 450                         lockdep_is_held(&nf_ct_proto_mutex)
 451                         ) != l4proto);
 452         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 453                            &nf_conntrack_l4proto_generic);
 454         mutex_unlock(&nf_ct_proto_mutex);
 455
 456         synchronize_rcu();
 457 }
 458 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 459
 460 void nf_ct_l4proto_pernet_unregister(struct net *net,
 461                                      struct nf_conntrack_l4proto *l4proto)
 462 {
 463         struct nf_proto_net *pn = NULL;
 464
 465         pn = nf_ct_l4proto_net(net, l4proto);
 466         if (pn == NULL)
 467                 return;
 468
 469         pn->users--;
 470         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 471
 472         /* Remove all contrack entries for this protocol */
 473         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
 474 }
 475 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 476
 477 int nf_conntrack_proto_pernet_init(struct net *net)
 478 {
 479         int err;
 480         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 481                                         &nf_conntrack_l4proto_generic);
 482
 483         err = nf_conntrack_l4proto_generic.init_net(net,
 484                                         nf_conntrack_l4proto_generic.l3proto);
 485         if (err < 0)
 486                 return err;
 487         err = nf_ct_l4proto_register_sysctl(net,
 488                                             pn,
 489                                             &nf_conntrack_l4proto_generic);
 490         if (err < 0)
 491                 return err;
 492
 493         pn->users++;
 494         return 0;
 495 }
 496
 497 void nf_conntrack_proto_pernet_fini(struct net *net)
 498 {
 499         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 500                                         &nf_conntrack_l4proto_generic);
 501
 502         pn->users--;
 503         nf_ct_l4proto_unregister_sysctl(net,
 504                                         pn,
 505                                         &nf_conntrack_l4proto_generic);
 506 }
 507
 508 int nf_conntrack_proto_init(void)
 509 {
 510         unsigned int i;
 511         for (i = 0; i < AF_MAX; i++)
 512                 rcu_assign_pointer(nf_ct_l3protos[i],
 513                                    &nf_conntrack_l3proto_generic);
 514         return 0;
 515 }
 516
 517 void nf_conntrack_proto_fini(void)
 518 {
 519         unsigned int i;
 520         /* free l3proto protocol tables */
 521         for (i = 0; i < PF_MAX; i++)
 522                 kfree(nf_ct_protos[i]);
 523 }