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 void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
  96 {
  97         module_put(p->me);
  98 }
  99 EXPORT_SYMBOL_GPL(nf_ct_l3proto_put);
 100
 101 int
 102 nf_ct_l3proto_try_module_get(unsigned short l3proto)
 103 {
 104         int ret;
 105         struct nf_conntrack_l3proto *p;
 106
 107 retry:  p = nf_ct_l3proto_find_get(l3proto);
 108         if (p == &nf_conntrack_l3proto_generic) {
 109                 ret = request_module("nf_conntrack-%d", l3proto);
 110                 if (!ret)
 111                         goto retry;
 112
 113                 return -EPROTOTYPE;
 114         }
 115
 116         return 0;
 117 }
 118 EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
 119
 120 void nf_ct_l3proto_module_put(unsigned short l3proto)
 121 {
 122         struct nf_conntrack_l3proto *p;
 123
 124         /* rcu_read_lock not necessary since the caller holds a reference, but
 125          * taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
 126          */
 127         rcu_read_lock();
 128         p = __nf_ct_l3proto_find(l3proto);
 129         module_put(p->me);
 130         rcu_read_unlock();
 131 }
 132 EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
 133
 134 struct nf_conntrack_l4proto *
 135 nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
 136 {
 137         struct nf_conntrack_l4proto *p;
 138
 139         rcu_read_lock();
 140         p = __nf_ct_l4proto_find(l3num, l4num);
 141         if (!try_module_get(p->me))
 142                 p = &nf_conntrack_l4proto_generic;
 143         rcu_read_unlock();
 144
 145         return p;
 146 }
 147 EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
 148
 149 void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
 150 {
 151         module_put(p->me);
 152 }
 153 EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
 154
 155 static int kill_l3proto(struct nf_conn *i, void *data)
 156 {
 157         return nf_ct_l3num(i) == ((struct nf_conntrack_l3proto *)data)->l3proto;
 158 }
 159
 160 static int kill_l4proto(struct nf_conn *i, void *data)
 161 {
 162         struct nf_conntrack_l4proto *l4proto;
 163         l4proto = (struct nf_conntrack_l4proto *)data;
 164         return nf_ct_protonum(i) == l4proto->l4proto &&
 165                nf_ct_l3num(i) == l4proto->l3proto;
 166 }
 167
 168 static struct nf_ip_net *nf_ct_l3proto_net(struct net *net,
 169                                            struct nf_conntrack_l3proto *l3proto)
 170 {
 171         if (l3proto->l3proto == PF_INET)
 172                 return &net->ct.nf_ct_proto;
 173         else
 174                 return NULL;
 175 }
 176
 177 static int nf_ct_l3proto_register_sysctl(struct net *net,
 178                                          struct nf_conntrack_l3proto *l3proto)
 179 {
 180         int err = 0;
 181         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
 182         /* nf_conntrack_l3proto_ipv6 doesn't support sysctl */
 183         if (in == NULL)
 184                 return 0;
 185
 186 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 187         if (in->ctl_table != NULL) {
 188                 err = nf_ct_register_sysctl(net,
 189                                             &in->ctl_table_header,
 190                                             l3proto->ctl_table_path,
 191                                             in->ctl_table);
 192                 if (err < 0) {
 193                         kfree(in->ctl_table);
 194                         in->ctl_table = NULL;
 195                 }
 196         }
 197 #endif
 198         return err;
 199 }
 200
 201 static void nf_ct_l3proto_unregister_sysctl(struct net *net,
 202                                             struct nf_conntrack_l3proto *l3proto)
 203 {
 204         struct nf_ip_net *in = nf_ct_l3proto_net(net, l3proto);
 205
 206         if (in == NULL)
 207                 return;
 208 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 209         if (in->ctl_table_header != NULL)
 210                 nf_ct_unregister_sysctl(&in->ctl_table_header,
 211                                         &in->ctl_table,
 212                                         0);
 213 #endif
 214 }
 215
 216 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 217 {
 218         int ret = 0;
 219         struct nf_conntrack_l3proto *old;
 220
 221         if (proto->l3proto >= AF_MAX)
 222                 return -EBUSY;
 223
 224         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 225                 return -EINVAL;
 226
 227         mutex_lock(&nf_ct_proto_mutex);
 228         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 229                                         lockdep_is_held(&nf_ct_proto_mutex));
 230         if (old != &nf_conntrack_l3proto_generic) {
 231                 ret = -EBUSY;
 232                 goto out_unlock;
 233         }
 234
 235         if (proto->nlattr_tuple_size)
 236                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 237
 238         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 239
 240 out_unlock:
 241         mutex_unlock(&nf_ct_proto_mutex);
 242         return ret;
 243
 244 }
 245 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 246
 247 int nf_ct_l3proto_pernet_register(struct net *net,
 248                                   struct nf_conntrack_l3proto *proto)
 249 {
 250         int ret = 0;
 251
 252         if (proto->init_net) {
 253                 ret = proto->init_net(net);
 254                 if (ret < 0)
 255                         return ret;
 256         }
 257
 258         return nf_ct_l3proto_register_sysctl(net, proto);
 259 }
 260 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
 261
 262 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 263 {
 264         BUG_ON(proto->l3proto >= AF_MAX);
 265
 266         mutex_lock(&nf_ct_proto_mutex);
 267         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 268                                          lockdep_is_held(&nf_ct_proto_mutex)
 269                                          ) != proto);
 270         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 271                            &nf_conntrack_l3proto_generic);
 272         mutex_unlock(&nf_ct_proto_mutex);
 273
 274         synchronize_rcu();
 275 }
 276 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 277
 278 void nf_ct_l3proto_pernet_unregister(struct net *net,
 279                                      struct nf_conntrack_l3proto *proto)
 280 {
 281         nf_ct_l3proto_unregister_sysctl(net, proto);
 282
 283         /* Remove all contrack entries for this protocol */
 284         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 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 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 322         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_table != NULL) {
 323                 if (err < 0) {
 324                         nf_ct_kfree_compat_sysctl_table(pn);
 325                         goto out;
 326                 }
 327                 err = nf_ct_register_sysctl(net,
 328                                             &pn->ctl_compat_header,
 329                                             "net/ipv4/netfilter",
 330                                             pn->ctl_compat_table);
 331                 if (err == 0)
 332                         goto out;
 333
 334                 nf_ct_kfree_compat_sysctl_table(pn);
 335                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 336                                         &pn->ctl_table,
 337                                         pn->users);
 338         }
 339 out:
 340 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 341 #endif /* CONFIG_SYSCTL */
 342         return err;
 343 }
 344
 345 static
 346 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 347                                      struct nf_proto_net *pn,
 348                                      struct nf_conntrack_l4proto *l4proto)
 349 {
 350 #ifdef CONFIG_SYSCTL
 351         if (pn->ctl_table_header != NULL)
 352                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 353                                         &pn->ctl_table,
 354                                         pn->users);
 355
 356 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 357         if (l4proto->l3proto != AF_INET6 && pn->ctl_compat_header != NULL)
 358                 nf_ct_unregister_sysctl(&pn->ctl_compat_header,
 359                                         &pn->ctl_compat_table,
 360                                         0);
 361 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 362 #endif /* CONFIG_SYSCTL */
 363 }
 364
 365 /* FIXME: Allow NULL functions and sub in pointers to generic for
 366    them. --RR */
 367 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 368 {
 369         int ret = 0;
 370
 371         if (l4proto->l3proto >= PF_MAX)
 372                 return -EBUSY;
 373
 374         if ((l4proto->to_nlattr && !l4proto->nlattr_size)
 375                 || (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 376                 return -EINVAL;
 377
 378         mutex_lock(&nf_ct_proto_mutex);
 379         if (!nf_ct_protos[l4proto->l3proto]) {
 380                 /* l3proto may be loaded latter. */
 381                 struct nf_conntrack_l4proto __rcu **proto_array;
 382                 int i;
 383
 384                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 385                                       sizeof(struct nf_conntrack_l4proto *),
 386                                       GFP_KERNEL);
 387                 if (proto_array == NULL) {
 388                         ret = -ENOMEM;
 389                         goto out_unlock;
 390                 }
 391
 392                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 393                         RCU_INIT_POINTER(proto_array[i], &nf_conntrack_l4proto_generic);
 394
 395                 /* Before making proto_array visible to lockless readers,
 396                  * we must make sure its content is committed to memory.
 397                  */
 398                 smp_wmb();
 399
 400                 nf_ct_protos[l4proto->l3proto] = proto_array;
 401         } else if (rcu_dereference_protected(
 402                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 403                         lockdep_is_held(&nf_ct_proto_mutex)
 404                         ) != &nf_conntrack_l4proto_generic) {
 405                 ret = -EBUSY;
 406                 goto out_unlock;
 407         }
 408
 409         l4proto->nla_size = 0;
 410         if (l4proto->nlattr_size)
 411                 l4proto->nla_size += l4proto->nlattr_size();
 412         if (l4proto->nlattr_tuple_size)
 413                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 414
 415         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 416                            l4proto);
 417 out_unlock:
 418         mutex_unlock(&nf_ct_proto_mutex);
 419         return ret;
 420 }
 421 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 422
 423 int nf_ct_l4proto_pernet_register(struct net *net,
 424                                   struct nf_conntrack_l4proto *l4proto)
 425 {
 426         int ret = 0;
 427         struct nf_proto_net *pn = NULL;
 428
 429         if (l4proto->init_net) {
 430                 ret = l4proto->init_net(net, l4proto->l3proto);
 431                 if (ret < 0)
 432                         goto out;
 433         }
 434
 435         pn = nf_ct_l4proto_net(net, l4proto);
 436         if (pn == NULL)
 437                 goto out;
 438
 439         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 440         if (ret < 0)
 441                 goto out;
 442
 443         pn->users++;
 444 out:
 445         return ret;
 446 }
 447 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 448
 449 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
 450 {
 451         BUG_ON(l4proto->l3proto >= PF_MAX);
 452
 453         mutex_lock(&nf_ct_proto_mutex);
 454         BUG_ON(rcu_dereference_protected(
 455                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 456                         lockdep_is_held(&nf_ct_proto_mutex)
 457                         ) != l4proto);
 458         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 459                            &nf_conntrack_l4proto_generic);
 460         mutex_unlock(&nf_ct_proto_mutex);
 461
 462         synchronize_rcu();
 463 }
 464 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 465
 466 void nf_ct_l4proto_pernet_unregister(struct net *net,
 467                                      struct nf_conntrack_l4proto *l4proto)
 468 {
 469         struct nf_proto_net *pn = NULL;
 470
 471         pn = nf_ct_l4proto_net(net, l4proto);
 472         if (pn == NULL)
 473                 return;
 474
 475         pn->users--;
 476         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 477
 478         /* Remove all contrack entries for this protocol */
 479         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
 480 }
 481 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 482
 483 int nf_conntrack_proto_pernet_init(struct net *net)
 484 {
 485         int err;
 486         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 487                                         &nf_conntrack_l4proto_generic);
 488
 489         err = nf_conntrack_l4proto_generic.init_net(net,
 490                                         nf_conntrack_l4proto_generic.l3proto);
 491         if (err < 0)
 492                 return err;
 493         err = nf_ct_l4proto_register_sysctl(net,
 494                                             pn,
 495                                             &nf_conntrack_l4proto_generic);
 496         if (err < 0)
 497                 return err;
 498
 499         pn->users++;
 500         return 0;
 501 }
 502
 503 void nf_conntrack_proto_pernet_fini(struct net *net)
 504 {
 505         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 506                                         &nf_conntrack_l4proto_generic);
 507
 508         pn->users--;
 509         nf_ct_l4proto_unregister_sysctl(net,
 510                                         pn,
 511                                         &nf_conntrack_l4proto_generic);
 512 }
 513
 514 int nf_conntrack_proto_init(void)
 515 {
 516         unsigned int i;
 517         for (i = 0; i < AF_MAX; i++)
 518                 rcu_assign_pointer(nf_ct_l3protos[i],
 519                                    &nf_conntrack_l3proto_generic);
 520         return 0;
 521 }
 522
 523 void nf_conntrack_proto_fini(void)
 524 {
 525         unsigned int i;
 526         /* free l3proto protocol tables */
 527         for (i = 0; i < PF_MAX; i++)
 528                 kfree(nf_ct_protos[i]);
 529 }