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 int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 163 {
 164         int ret = 0;
 165         struct nf_conntrack_l3proto *old;
 166
 167         if (proto->l3proto >= AF_MAX)
 168                 return -EBUSY;
 169
 170         if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
 171                 return -EINVAL;
 172
 173         mutex_lock(&nf_ct_proto_mutex);
 174         old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 175                                         lockdep_is_held(&nf_ct_proto_mutex));
 176         if (old != &nf_conntrack_l3proto_generic) {
 177                 ret = -EBUSY;
 178                 goto out_unlock;
 179         }
 180
 181         if (proto->nlattr_tuple_size)
 182                 proto->nla_size = 3 * proto->nlattr_tuple_size();
 183
 184         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 185
 186 out_unlock:
 187         mutex_unlock(&nf_ct_proto_mutex);
 188         return ret;
 189
 190 }
 191 EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 192
 193 int nf_ct_l3proto_pernet_register(struct net *net,
 194                                   struct nf_conntrack_l3proto *proto)
 195 {
 196         int ret;
 197
 198         if (proto->init_net) {
 199                 ret = proto->init_net(net);
 200                 if (ret < 0)
 201                         return ret;
 202         }
 203
 204         return 0;
 205 }
 206 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);
 207
 208 void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
 209 {
 210         BUG_ON(proto->l3proto >= AF_MAX);
 211
 212         mutex_lock(&nf_ct_proto_mutex);
 213         BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 214                                          lockdep_is_held(&nf_ct_proto_mutex)
 215                                          ) != proto);
 216         rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
 217                            &nf_conntrack_l3proto_generic);
 218         mutex_unlock(&nf_ct_proto_mutex);
 219
 220         synchronize_rcu();
 221 }
 222 EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
 223
 224 void nf_ct_l3proto_pernet_unregister(struct net *net,
 225                                      struct nf_conntrack_l3proto *proto)
 226 {
 227         /* Remove all contrack entries for this protocol */
 228         nf_ct_iterate_cleanup(net, kill_l3proto, proto, 0, 0);
 229 }
 230 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_unregister);
 231
 232 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 233                                               struct nf_conntrack_l4proto *l4proto)
 234 {
 235         if (l4proto->get_net_proto) {
 236                 /* statically built-in protocols use static per-net */
 237                 return l4proto->get_net_proto(net);
 238         } else if (l4proto->net_id) {
 239                 /* ... and loadable protocols use dynamic per-net */
 240                 return net_generic(net, *l4proto->net_id);
 241         }
 242         return NULL;
 243 }
 244
 245 static
 246 int nf_ct_l4proto_register_sysctl(struct net *net,
 247                                   struct nf_proto_net *pn,
 248                                   struct nf_conntrack_l4proto *l4proto)
 249 {
 250         int err = 0;
 251
 252 #ifdef CONFIG_SYSCTL
 253         if (pn->ctl_table != NULL) {
 254                 err = nf_ct_register_sysctl(net,
 255                                             &pn->ctl_table_header,
 256                                             "net/netfilter",
 257                                             pn->ctl_table);
 258                 if (err < 0) {
 259                         if (!pn->users) {
 260                                 kfree(pn->ctl_table);
 261                                 pn->ctl_table = NULL;
 262                         }
 263                 }
 264         }
 265 #endif /* CONFIG_SYSCTL */
 266         return err;
 267 }
 268
 269 static
 270 void nf_ct_l4proto_unregister_sysctl(struct net *net,
 271                                      struct nf_proto_net *pn,
 272                                      struct nf_conntrack_l4proto *l4proto)
 273 {
 274 #ifdef CONFIG_SYSCTL
 275         if (pn->ctl_table_header != NULL)
 276                 nf_ct_unregister_sysctl(&pn->ctl_table_header,
 277                                         &pn->ctl_table,
 278                                         pn->users);
 279 #endif /* CONFIG_SYSCTL */
 280 }
 281
 282 /* FIXME: Allow NULL functions and sub in pointers to generic for
 283    them. --RR */
 284 int nf_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
 285 {
 286         int ret = 0;
 287
 288         if (l4proto->l3proto >= PF_MAX)
 289                 return -EBUSY;
 290
 291         if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
 292             (l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
 293                 return -EINVAL;
 294
 295         mutex_lock(&nf_ct_proto_mutex);
 296         if (!nf_ct_protos[l4proto->l3proto]) {
 297                 /* l3proto may be loaded latter. */
 298                 struct nf_conntrack_l4proto __rcu **proto_array;
 299                 int i;
 300
 301                 proto_array = kmalloc(MAX_NF_CT_PROTO *
 302                                       sizeof(struct nf_conntrack_l4proto *),
 303                                       GFP_KERNEL);
 304                 if (proto_array == NULL) {
 305                         ret = -ENOMEM;
 306                         goto out_unlock;
 307                 }
 308
 309                 for (i = 0; i < MAX_NF_CT_PROTO; i++)
 310                         RCU_INIT_POINTER(proto_array[i],
 311                                          &nf_conntrack_l4proto_generic);
 312
 313                 /* Before making proto_array visible to lockless readers,
 314                  * we must make sure its content is committed to memory.
 315                  */
 316                 smp_wmb();
 317
 318                 nf_ct_protos[l4proto->l3proto] = proto_array;
 319         } else if (rcu_dereference_protected(
 320                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 321                         lockdep_is_held(&nf_ct_proto_mutex)
 322                         ) != &nf_conntrack_l4proto_generic) {
 323                 ret = -EBUSY;
 324                 goto out_unlock;
 325         }
 326
 327         l4proto->nla_size = 0;
 328         if (l4proto->nlattr_size)
 329                 l4proto->nla_size += l4proto->nlattr_size();
 330         if (l4proto->nlattr_tuple_size)
 331                 l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 332
 333         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 334                            l4proto);
 335 out_unlock:
 336         mutex_unlock(&nf_ct_proto_mutex);
 337         return ret;
 338 }
 339 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
 340
 341 int nf_ct_l4proto_pernet_register_one(struct net *net,
 342                                       struct nf_conntrack_l4proto *l4proto)
 343 {
 344         int ret = 0;
 345         struct nf_proto_net *pn = NULL;
 346
 347         if (l4proto->init_net) {
 348                 ret = l4proto->init_net(net, l4proto->l3proto);
 349                 if (ret < 0)
 350                         goto out;
 351         }
 352
 353         pn = nf_ct_l4proto_net(net, l4proto);
 354         if (pn == NULL)
 355                 goto out;
 356
 357         ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
 358         if (ret < 0)
 359                 goto out;
 360
 361         pn->users++;
 362 out:
 363         return ret;
 364 }
 365 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
 366
 367 void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
 368 {
 369         BUG_ON(l4proto->l3proto >= PF_MAX);
 370
 371         mutex_lock(&nf_ct_proto_mutex);
 372         BUG_ON(rcu_dereference_protected(
 373                         nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 374                         lockdep_is_held(&nf_ct_proto_mutex)
 375                         ) != l4proto);
 376         rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 377                            &nf_conntrack_l4proto_generic);
 378         mutex_unlock(&nf_ct_proto_mutex);
 379
 380         synchronize_rcu();
 381 }
 382 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
 383
 384 void nf_ct_l4proto_pernet_unregister_one(struct net *net,
 385                                          struct nf_conntrack_l4proto *l4proto)
 386 {
 387         struct nf_proto_net *pn = NULL;
 388
 389         pn = nf_ct_l4proto_net(net, l4proto);
 390         if (pn == NULL)
 391                 return;
 392
 393         pn->users--;
 394         nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
 395
 396         /* Remove all contrack entries for this protocol */
 397         nf_ct_iterate_cleanup(net, kill_l4proto, l4proto, 0, 0);
 398 }
 399 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
 400
 401 int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
 402                            unsigned int num_proto)
 403 {
 404         int ret = -EINVAL, ver;
 405         unsigned int i;
 406
 407         for (i = 0; i < num_proto; i++) {
 408                 ret = nf_ct_l4proto_register_one(l4proto[i]);
 409                 if (ret < 0)
 410                         break;
 411         }
 412         if (i != num_proto) {
 413                 ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
 414                 pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
 415                        ver, l4proto[i]->name, ver);
 416                 nf_ct_l4proto_unregister(l4proto, i);
 417         }
 418         return ret;
 419 }
 420 EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
 421
 422 int nf_ct_l4proto_pernet_register(struct net *net,
 423                                   struct nf_conntrack_l4proto *l4proto[],
 424                                   unsigned int num_proto)
 425 {
 426         int ret = -EINVAL;
 427         unsigned int i;
 428
 429         for (i = 0; i < num_proto; i++) {
 430                 ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
 431                 if (ret < 0)
 432                         break;
 433         }
 434         if (i != num_proto) {
 435                 pr_err("nf_conntrack_%s%d: pernet registration failed\n",
 436                        l4proto[i]->name,
 437                        l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
 438                 nf_ct_l4proto_pernet_unregister(net, l4proto, i);
 439         }
 440         return ret;
 441 }
 442 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
 443
 444 void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
 445                               unsigned int num_proto)
 446 {
 447         while (num_proto-- != 0)
 448                 nf_ct_l4proto_unregister_one(l4proto[num_proto]);
 449 }
 450 EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
 451
 452 void nf_ct_l4proto_pernet_unregister(struct net *net,
 453                                      struct nf_conntrack_l4proto *l4proto[],
 454                                      unsigned int num_proto)
 455 {
 456         while (num_proto-- != 0)
 457                 nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
 458 }
 459 EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
 460
 461 int nf_conntrack_proto_pernet_init(struct net *net)
 462 {
 463         int err;
 464         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 465                                         &nf_conntrack_l4proto_generic);
 466
 467         err = nf_conntrack_l4proto_generic.init_net(net,
 468                                         nf_conntrack_l4proto_generic.l3proto);
 469         if (err < 0)
 470                 return err;
 471         err = nf_ct_l4proto_register_sysctl(net,
 472                                             pn,
 473                                             &nf_conntrack_l4proto_generic);
 474         if (err < 0)
 475                 return err;
 476
 477         pn->users++;
 478         return 0;
 479 }
 480
 481 void nf_conntrack_proto_pernet_fini(struct net *net)
 482 {
 483         struct nf_proto_net *pn = nf_ct_l4proto_net(net,
 484                                         &nf_conntrack_l4proto_generic);
 485
 486         pn->users--;
 487         nf_ct_l4proto_unregister_sysctl(net,
 488                                         pn,
 489                                         &nf_conntrack_l4proto_generic);
 490 }
 491
 492 int nf_conntrack_proto_init(void)
 493 {
 494         unsigned int i;
 495         for (i = 0; i < AF_MAX; i++)
 496                 rcu_assign_pointer(nf_ct_l3protos[i],
 497                                    &nf_conntrack_l3proto_generic);
 498         return 0;
 499 }
 500
 501 void nf_conntrack_proto_fini(void)
 502 {
 503         unsigned int i;
 504         /* free l3proto protocol tables */
 505         for (i = 0; i < PF_MAX; i++)
 506                 kfree(nf_ct_protos[i]);
 507 }