net/netfilter/nfnetlink.c

   1 /* Netfilter messages via netlink socket. Allows for user space
   2  * protocol helpers and general trouble making from userspace.
   3  *
   4  * (C) 2001 by Jay Schulist <jschlst@samba.org>,
   5  * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
   6  * (C) 2005-2017 by Pablo Neira Ayuso <pablo@netfilter.org>
   7  *
   8  * Initial netfilter messages via netlink development funded and
   9  * generally made possible by Network Robots, Inc. (www.networkrobots.com)
  10  *
  11  * Further development of this code funded by Astaro AG (http://www.astaro.com)
  12  *
  13  * This software may be used and distributed according to the terms
  14  * of the GNU General Public License, incorporated herein by reference.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/types.h>
  19 #include <linux/socket.h>
  20 #include <linux/kernel.h>
  21 #include <linux/string.h>
  22 #include <linux/sockios.h>
  23 #include <linux/net.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/uaccess.h>
  26 #include <net/sock.h>
  27 #include <linux/init.h>
  28 #include <linux/sched/signal.h>
  29
  30 #include <net/netlink.h>
  31 #include <linux/netfilter/nfnetlink.h>
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  35 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
  36
  37 #define nfnl_dereference_protected(id) \
  38         rcu_dereference_protected(table[(id)].subsys, \
  39                                   lockdep_nfnl_is_held((id)))
  40
  41 #define NFNL_MAX_ATTR_COUNT     32
  42
  43 static struct {
  44         struct mutex                            mutex;
  45         const struct nfnetlink_subsystem __rcu  *subsys;
  46 } table[NFNL_SUBSYS_COUNT];
  47
  48 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
  49         [NFNLGRP_CONNTRACK_NEW]         = NFNL_SUBSYS_CTNETLINK,
  50         [NFNLGRP_CONNTRACK_UPDATE]      = NFNL_SUBSYS_CTNETLINK,
  51         [NFNLGRP_CONNTRACK_DESTROY]     = NFNL_SUBSYS_CTNETLINK,
  52         [NFNLGRP_CONNTRACK_EXP_NEW]     = NFNL_SUBSYS_CTNETLINK_EXP,
  53         [NFNLGRP_CONNTRACK_EXP_UPDATE]  = NFNL_SUBSYS_CTNETLINK_EXP,
  54         [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
  55         [NFNLGRP_NFTABLES]              = NFNL_SUBSYS_NFTABLES,
  56         [NFNLGRP_ACCT_QUOTA]            = NFNL_SUBSYS_ACCT,
  57         [NFNLGRP_NFTRACE]               = NFNL_SUBSYS_NFTABLES,
  58 };
  59
  60 void nfnl_lock(__u8 subsys_id)
  61 {
  62         mutex_lock(&table[subsys_id].mutex);
  63 }
  64 EXPORT_SYMBOL_GPL(nfnl_lock);
  65
  66 void nfnl_unlock(__u8 subsys_id)
  67 {
  68         mutex_unlock(&table[subsys_id].mutex);
  69 }
  70 EXPORT_SYMBOL_GPL(nfnl_unlock);
  71
  72 #ifdef CONFIG_PROVE_LOCKING
  73 bool lockdep_nfnl_is_held(u8 subsys_id)
  74 {
  75         return lockdep_is_held(&table[subsys_id].mutex);
  76 }
  77 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
  78 #endif
  79
  80 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
  81 {
  82         u8 cb_id;
  83
  84         /* Sanity-check attr_count size to avoid stack buffer overflow. */
  85         for (cb_id = 0; cb_id < n->cb_count; cb_id++)
  86                 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
  87                         return -EINVAL;
  88
  89         nfnl_lock(n->subsys_id);
  90         if (table[n->subsys_id].subsys) {
  91                 nfnl_unlock(n->subsys_id);
  92                 return -EBUSY;
  93         }
  94         rcu_assign_pointer(table[n->subsys_id].subsys, n);
  95         nfnl_unlock(n->subsys_id);
  96
  97         return 0;
  98 }
  99 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
 100
 101 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
 102 {
 103         nfnl_lock(n->subsys_id);
 104         table[n->subsys_id].subsys = NULL;
 105         nfnl_unlock(n->subsys_id);
 106         synchronize_rcu();
 107         return 0;
 108 }
 109 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
 110
 111 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
 112 {
 113         u8 subsys_id = NFNL_SUBSYS_ID(type);
 114
 115         if (subsys_id >= NFNL_SUBSYS_COUNT)
 116                 return NULL;
 117
 118         return rcu_dereference(table[subsys_id].subsys);
 119 }
 120
 121 static inline const struct nfnl_callback *
 122 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
 123 {
 124         u8 cb_id = NFNL_MSG_TYPE(type);
 125
 126         if (cb_id >= ss->cb_count)
 127                 return NULL;
 128
 129         return &ss->cb[cb_id];
 130 }
 131
 132 int nfnetlink_has_listeners(struct net *net, unsigned int group)
 133 {
 134         return netlink_has_listeners(net->nfnl, group);
 135 }
 136 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
 137
 138 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
 139                    unsigned int group, int echo, gfp_t flags)
 140 {
 141         return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
 142 }
 143 EXPORT_SYMBOL_GPL(nfnetlink_send);
 144
 145 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
 146 {
 147         return netlink_set_err(net->nfnl, portid, group, error);
 148 }
 149 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
 150
 151 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
 152 {
 153         int err;
 154
 155         err = nlmsg_unicast(net->nfnl, skb, portid);
 156         if (err == -EAGAIN)
 157                 err = -ENOBUFS;
 158
 159         return err;
 160 }
 161 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
 162
 163 /* Process one complete nfnetlink message. */
 164 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 165                              struct netlink_ext_ack *extack)
 166 {
 167         struct net *net = sock_net(skb->sk);
 168         const struct nfnl_callback *nc;
 169         const struct nfnetlink_subsystem *ss;
 170         int type, err;
 171
 172         /* All the messages must at least contain nfgenmsg */
 173         if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
 174                 return 0;
 175
 176         type = nlh->nlmsg_type;
 177 replay:
 178         rcu_read_lock();
 179         ss = nfnetlink_get_subsys(type);
 180         if (!ss) {
 181 #ifdef CONFIG_MODULES
 182                 rcu_read_unlock();
 183                 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
 184                 rcu_read_lock();
 185                 ss = nfnetlink_get_subsys(type);
 186                 if (!ss)
 187 #endif
 188                 {
 189                         rcu_read_unlock();
 190                         return -EINVAL;
 191                 }
 192         }
 193
 194         nc = nfnetlink_find_client(type, ss);
 195         if (!nc) {
 196                 rcu_read_unlock();
 197                 return -EINVAL;
 198         }
 199
 200         {
 201                 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 202                 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 203                 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 204                 struct nlattr *attr = (void *)nlh + min_len;
 205                 int attrlen = nlh->nlmsg_len - min_len;
 206                 __u8 subsys_id = NFNL_SUBSYS_ID(type);
 207
 208                 /* Sanity-check NFNL_MAX_ATTR_COUNT */
 209                 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 210                         rcu_read_unlock();
 211                         return -ENOMEM;
 212                 }
 213
 214                 err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen,
 215                                 ss->cb[cb_id].policy, extack);
 216                 if (err < 0) {
 217                         rcu_read_unlock();
 218                         return err;
 219                 }
 220
 221                 if (nc->call_rcu) {
 222                         err = nc->call_rcu(net, net->nfnl, skb, nlh,
 223                                            (const struct nlattr **)cda,
 224                                            extack);
 225                         rcu_read_unlock();
 226                 } else {
 227                         rcu_read_unlock();
 228                         nfnl_lock(subsys_id);
 229                         if (nfnl_dereference_protected(subsys_id) != ss ||
 230                             nfnetlink_find_client(type, ss) != nc)
 231                                 err = -EAGAIN;
 232                         else if (nc->call)
 233                                 err = nc->call(net, net->nfnl, skb, nlh,
 234                                                (const struct nlattr **)cda,
 235                                                extack);
 236                         else
 237                                 err = -EINVAL;
 238                         nfnl_unlock(subsys_id);
 239                 }
 240                 if (err == -EAGAIN)
 241                         goto replay;
 242                 return err;
 243         }
 244 }
 245
 246 struct nfnl_err {
 247         struct list_head        head;
 248         struct nlmsghdr         *nlh;
 249         int                     err;
 250         struct netlink_ext_ack  extack;
 251 };
 252
 253 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
 254                         const struct netlink_ext_ack *extack)
 255 {
 256         struct nfnl_err *nfnl_err;
 257
 258         nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
 259         if (nfnl_err == NULL)
 260                 return -ENOMEM;
 261
 262         nfnl_err->nlh = nlh;
 263         nfnl_err->err = err;
 264         nfnl_err->extack = *extack;
 265         list_add_tail(&nfnl_err->head, list);
 266
 267         return 0;
 268 }
 269
 270 static void nfnl_err_del(struct nfnl_err *nfnl_err)
 271 {
 272         list_del(&nfnl_err->head);
 273         kfree(nfnl_err);
 274 }
 275
 276 static void nfnl_err_reset(struct list_head *err_list)
 277 {
 278         struct nfnl_err *nfnl_err, *next;
 279
 280         list_for_each_entry_safe(nfnl_err, next, err_list, head)
 281                 nfnl_err_del(nfnl_err);
 282 }
 283
 284 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
 285 {
 286         struct nfnl_err *nfnl_err, *next;
 287
 288         list_for_each_entry_safe(nfnl_err, next, err_list, head) {
 289                 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
 290                             &nfnl_err->extack);
 291                 nfnl_err_del(nfnl_err);
 292         }
 293 }
 294
 295 enum {
 296         NFNL_BATCH_FAILURE      = (1 << 0),
 297         NFNL_BATCH_DONE         = (1 << 1),
 298         NFNL_BATCH_REPLAY       = (1 << 2),
 299 };
 300
 301 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
 302                                 u16 subsys_id, u32 genid)
 303 {
 304         struct sk_buff *oskb = skb;
 305         struct net *net = sock_net(skb->sk);
 306         const struct nfnetlink_subsystem *ss;
 307         const struct nfnl_callback *nc;
 308         struct netlink_ext_ack extack;
 309         LIST_HEAD(err_list);
 310         u32 status;
 311         int err;
 312
 313         if (subsys_id >= NFNL_SUBSYS_COUNT)
 314                 return netlink_ack(skb, nlh, -EINVAL, NULL);
 315 replay:
 316         status = 0;
 317
 318         skb = netlink_skb_clone(oskb, GFP_KERNEL);
 319         if (!skb)
 320                 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
 321
 322         nfnl_lock(subsys_id);
 323         ss = nfnl_dereference_protected(subsys_id);
 324         if (!ss) {
 325 #ifdef CONFIG_MODULES
 326                 nfnl_unlock(subsys_id);
 327                 request_module("nfnetlink-subsys-%d", subsys_id);
 328                 nfnl_lock(subsys_id);
 329                 ss = nfnl_dereference_protected(subsys_id);
 330                 if (!ss)
 331 #endif
 332                 {
 333                         nfnl_unlock(subsys_id);
 334                         netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 335                         return kfree_skb(skb);
 336                 }
 337         }
 338
 339         if (!ss->valid_genid || !ss->commit || !ss->abort) {
 340                 nfnl_unlock(subsys_id);
 341                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 342                 return kfree_skb(skb);
 343         }
 344
 345         if (!try_module_get(ss->owner)) {
 346                 nfnl_unlock(subsys_id);
 347                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 348                 return kfree_skb(skb);
 349         }
 350
 351         if (!ss->valid_genid(net, genid)) {
 352                 module_put(ss->owner);
 353                 nfnl_unlock(subsys_id);
 354                 netlink_ack(oskb, nlh, -ERESTART, NULL);
 355                 return kfree_skb(skb);
 356         }
 357
 358         nfnl_unlock(subsys_id);
 359
 360         while (skb->len >= nlmsg_total_size(0)) {
 361                 int msglen, type;
 362
 363                 if (fatal_signal_pending(current)) {
 364                         nfnl_err_reset(&err_list);
 365                         err = -EINTR;
 366                         status = NFNL_BATCH_FAILURE;
 367                         goto done;
 368                 }
 369
 370                 memset(&extack, 0, sizeof(extack));
 371                 nlh = nlmsg_hdr(skb);
 372                 err = 0;
 373
 374                 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
 375                     skb->len < nlh->nlmsg_len ||
 376                     nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
 377                         nfnl_err_reset(&err_list);
 378                         status |= NFNL_BATCH_FAILURE;
 379                         goto done;
 380                 }
 381
 382                 /* Only requests are handled by the kernel */
 383                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
 384                         err = -EINVAL;
 385                         goto ack;
 386                 }
 387
 388                 type = nlh->nlmsg_type;
 389                 if (type == NFNL_MSG_BATCH_BEGIN) {
 390                         /* Malformed: Batch begin twice */
 391                         nfnl_err_reset(&err_list);
 392                         status |= NFNL_BATCH_FAILURE;
 393                         goto done;
 394                 } else if (type == NFNL_MSG_BATCH_END) {
 395                         status |= NFNL_BATCH_DONE;
 396                         goto done;
 397                 } else if (type < NLMSG_MIN_TYPE) {
 398                         err = -EINVAL;
 399                         goto ack;
 400                 }
 401
 402                 /* We only accept a batch with messages for the same
 403                  * subsystem.
 404                  */
 405                 if (NFNL_SUBSYS_ID(type) != subsys_id) {
 406                         err = -EINVAL;
 407                         goto ack;
 408                 }
 409
 410                 nc = nfnetlink_find_client(type, ss);
 411                 if (!nc) {
 412                         err = -EINVAL;
 413                         goto ack;
 414                 }
 415
 416                 {
 417                         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 418                         u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 419                         struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 420                         struct nlattr *attr = (void *)nlh + min_len;
 421                         int attrlen = nlh->nlmsg_len - min_len;
 422
 423                         /* Sanity-check NFTA_MAX_ATTR */
 424                         if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 425                                 err = -ENOMEM;
 426                                 goto ack;
 427                         }
 428
 429                         err = nla_parse(cda, ss->cb[cb_id].attr_count, attr,
 430                                         attrlen, ss->cb[cb_id].policy, NULL);
 431                         if (err < 0)
 432                                 goto ack;
 433
 434                         if (nc->call_batch) {
 435                                 err = nc->call_batch(net, net->nfnl, skb, nlh,
 436                                                      (const struct nlattr **)cda,
 437                                                      &extack);
 438                         }
 439
 440                         /* The lock was released to autoload some module, we
 441                          * have to abort and start from scratch using the
 442                          * original skb.
 443                          */
 444                         if (err == -EAGAIN) {
 445                                 status |= NFNL_BATCH_REPLAY;
 446                                 goto done;
 447                         }
 448                 }
 449 ack:
 450                 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
 451                         /* Errors are delivered once the full batch has been
 452                          * processed, this avoids that the same error is
 453                          * reported several times when replaying the batch.
 454                          */
 455                         if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
 456                                 /* We failed to enqueue an error, reset the
 457                                  * list of errors and send OOM to userspace
 458                                  * pointing to the batch header.
 459                                  */
 460                                 nfnl_err_reset(&err_list);
 461                                 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
 462                                             NULL);
 463                                 status |= NFNL_BATCH_FAILURE;
 464                                 goto done;
 465                         }
 466                         /* We don't stop processing the batch on errors, thus,
 467                          * userspace gets all the errors that the batch
 468                          * triggers.
 469                          */
 470                         if (err)
 471                                 status |= NFNL_BATCH_FAILURE;
 472                 }
 473
 474                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 475                 if (msglen > skb->len)
 476                         msglen = skb->len;
 477                 skb_pull(skb, msglen);
 478         }
 479 done:
 480         if (status & NFNL_BATCH_REPLAY) {
 481                 ss->abort(net, oskb);
 482                 nfnl_err_reset(&err_list);
 483                 kfree_skb(skb);
 484                 module_put(ss->owner);
 485                 goto replay;
 486         } else if (status == NFNL_BATCH_DONE) {
 487                 err = ss->commit(net, oskb);
 488                 if (err == -EAGAIN) {
 489                         status |= NFNL_BATCH_REPLAY;
 490                         goto done;
 491                 } else if (err) {
 492                         ss->abort(net, oskb);
 493                         netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
 494                 }
 495         } else {
 496                 ss->abort(net, oskb);
 497         }
 498         if (ss->cleanup)
 499                 ss->cleanup(net);
 500
 501         nfnl_err_deliver(&err_list, oskb);
 502         kfree_skb(skb);
 503         module_put(ss->owner);
 504 }
 505
 506 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
 507         [NFNL_BATCH_GENID]      = { .type = NLA_U32 },
 508 };
 509
 510 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
 511 {
 512         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 513         struct nlattr *attr = (void *)nlh + min_len;
 514         struct nlattr *cda[NFNL_BATCH_MAX + 1];
 515         int attrlen = nlh->nlmsg_len - min_len;
 516         struct nfgenmsg *nfgenmsg;
 517         int msglen, err;
 518         u32 gen_id = 0;
 519         u16 res_id;
 520
 521         msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 522         if (msglen > skb->len)
 523                 msglen = skb->len;
 524
 525         if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
 526                 return;
 527
 528         err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy,
 529                         NULL);
 530         if (err < 0) {
 531                 netlink_ack(skb, nlh, err, NULL);
 532                 return;
 533         }
 534         if (cda[NFNL_BATCH_GENID])
 535                 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
 536
 537         nfgenmsg = nlmsg_data(nlh);
 538         skb_pull(skb, msglen);
 539         /* Work around old nft using host byte order */
 540         if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
 541                 res_id = NFNL_SUBSYS_NFTABLES;
 542         else
 543                 res_id = ntohs(nfgenmsg->res_id);
 544
 545         nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
 546 }
 547
 548 static void nfnetlink_rcv(struct sk_buff *skb)
 549 {
 550         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 551
 552         if (skb->len < NLMSG_HDRLEN ||
 553             nlh->nlmsg_len < NLMSG_HDRLEN ||
 554             skb->len < nlh->nlmsg_len)
 555                 return;
 556
 557         if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
 558                 netlink_ack(skb, nlh, -EPERM, NULL);
 559                 return;
 560         }
 561
 562         if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
 563                 nfnetlink_rcv_skb_batch(skb, nlh);
 564         else
 565                 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
 566 }
 567
 568 #ifdef CONFIG_MODULES
 569 static int nfnetlink_bind(struct net *net, int group)
 570 {
 571         const struct nfnetlink_subsystem *ss;
 572         int type;
 573
 574         if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
 575                 return 0;
 576
 577         type = nfnl_group2type[group];
 578
 579         rcu_read_lock();
 580         ss = nfnetlink_get_subsys(type << 8);
 581         rcu_read_unlock();
 582         if (!ss)
 583                 request_module_nowait("nfnetlink-subsys-%d", type);
 584         return 0;
 585 }
 586 #endif
 587
 588 static int __net_init nfnetlink_net_init(struct net *net)
 589 {
 590         struct sock *nfnl;
 591         struct netlink_kernel_cfg cfg = {
 592                 .groups = NFNLGRP_MAX,
 593                 .input  = nfnetlink_rcv,
 594 #ifdef CONFIG_MODULES
 595                 .bind   = nfnetlink_bind,
 596 #endif
 597         };
 598
 599         nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
 600         if (!nfnl)
 601                 return -ENOMEM;
 602         net->nfnl_stash = nfnl;
 603         rcu_assign_pointer(net->nfnl, nfnl);
 604         return 0;
 605 }
 606
 607 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
 608 {
 609         struct net *net;
 610
 611         list_for_each_entry(net, net_exit_list, exit_list)
 612                 RCU_INIT_POINTER(net->nfnl, NULL);
 613         synchronize_net();
 614         list_for_each_entry(net, net_exit_list, exit_list)
 615                 netlink_kernel_release(net->nfnl_stash);
 616 }
 617
 618 static struct pernet_operations nfnetlink_net_ops = {
 619         .init           = nfnetlink_net_init,
 620         .exit_batch     = nfnetlink_net_exit_batch,
 621 };
 622
 623 static int __init nfnetlink_init(void)
 624 {
 625         int i;
 626
 627         for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
 628                 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
 629
 630         for (i=0; i<NFNL_SUBSYS_COUNT; i++)
 631                 mutex_init(&table[i].mutex);
 632
 633         return register_pernet_subsys(&nfnetlink_net_ops);
 634 }
 635
 636 static void __exit nfnetlink_exit(void)
 637 {
 638         unregister_pernet_subsys(&nfnetlink_net_ops);
 639 }
 640 module_init(nfnetlink_init);
 641 module_exit(nfnetlink_exit);