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 MODULE_DESCRIPTION("Netfilter messages via netlink socket");
  37
  38 #define nfnl_dereference_protected(id) \
  39         rcu_dereference_protected(table[(id)].subsys, \
  40                                   lockdep_nfnl_is_held((id)))
  41
  42 #define NFNL_MAX_ATTR_COUNT     32
  43
  44 static struct {
  45         struct mutex                            mutex;
  46         const struct nfnetlink_subsystem __rcu  *subsys;
  47 } table[NFNL_SUBSYS_COUNT];
  48
  49 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
  50         [NFNLGRP_CONNTRACK_NEW]         = NFNL_SUBSYS_CTNETLINK,
  51         [NFNLGRP_CONNTRACK_UPDATE]      = NFNL_SUBSYS_CTNETLINK,
  52         [NFNLGRP_CONNTRACK_DESTROY]     = NFNL_SUBSYS_CTNETLINK,
  53         [NFNLGRP_CONNTRACK_EXP_NEW]     = NFNL_SUBSYS_CTNETLINK_EXP,
  54         [NFNLGRP_CONNTRACK_EXP_UPDATE]  = NFNL_SUBSYS_CTNETLINK_EXP,
  55         [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
  56         [NFNLGRP_NFTABLES]              = NFNL_SUBSYS_NFTABLES,
  57         [NFNLGRP_ACCT_QUOTA]            = NFNL_SUBSYS_ACCT,
  58         [NFNLGRP_NFTRACE]               = NFNL_SUBSYS_NFTABLES,
  59 };
  60
  61 void nfnl_lock(__u8 subsys_id)
  62 {
  63         mutex_lock(&table[subsys_id].mutex);
  64 }
  65 EXPORT_SYMBOL_GPL(nfnl_lock);
  66
  67 void nfnl_unlock(__u8 subsys_id)
  68 {
  69         mutex_unlock(&table[subsys_id].mutex);
  70 }
  71 EXPORT_SYMBOL_GPL(nfnl_unlock);
  72
  73 #ifdef CONFIG_PROVE_LOCKING
  74 bool lockdep_nfnl_is_held(u8 subsys_id)
  75 {
  76         return lockdep_is_held(&table[subsys_id].mutex);
  77 }
  78 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
  79 #endif
  80
  81 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
  82 {
  83         u8 cb_id;
  84
  85         /* Sanity-check attr_count size to avoid stack buffer overflow. */
  86         for (cb_id = 0; cb_id < n->cb_count; cb_id++)
  87                 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
  88                         return -EINVAL;
  89
  90         nfnl_lock(n->subsys_id);
  91         if (table[n->subsys_id].subsys) {
  92                 nfnl_unlock(n->subsys_id);
  93                 return -EBUSY;
  94         }
  95         rcu_assign_pointer(table[n->subsys_id].subsys, n);
  96         nfnl_unlock(n->subsys_id);
  97
  98         return 0;
  99 }
 100 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
 101
 102 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
 103 {
 104         nfnl_lock(n->subsys_id);
 105         table[n->subsys_id].subsys = NULL;
 106         nfnl_unlock(n->subsys_id);
 107         synchronize_rcu();
 108         return 0;
 109 }
 110 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
 111
 112 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
 113 {
 114         u8 subsys_id = NFNL_SUBSYS_ID(type);
 115
 116         if (subsys_id >= NFNL_SUBSYS_COUNT)
 117                 return NULL;
 118
 119         return rcu_dereference(table[subsys_id].subsys);
 120 }
 121
 122 static inline const struct nfnl_callback *
 123 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
 124 {
 125         u8 cb_id = NFNL_MSG_TYPE(type);
 126
 127         if (cb_id >= ss->cb_count)
 128                 return NULL;
 129
 130         return &ss->cb[cb_id];
 131 }
 132
 133 int nfnetlink_has_listeners(struct net *net, unsigned int group)
 134 {
 135         return netlink_has_listeners(net->nfnl, group);
 136 }
 137 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
 138
 139 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
 140                    unsigned int group, int echo, gfp_t flags)
 141 {
 142         return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
 143 }
 144 EXPORT_SYMBOL_GPL(nfnetlink_send);
 145
 146 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
 147 {
 148         return netlink_set_err(net->nfnl, portid, group, error);
 149 }
 150 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
 151
 152 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
 153 {
 154         int err;
 155
 156         err = nlmsg_unicast(net->nfnl, skb, portid);
 157         if (err == -EAGAIN)
 158                 err = -ENOBUFS;
 159
 160         return err;
 161 }
 162 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
 163
 164 /* Process one complete nfnetlink message. */
 165 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 166                              struct netlink_ext_ack *extack)
 167 {
 168         struct net *net = sock_net(skb->sk);
 169         const struct nfnl_callback *nc;
 170         const struct nfnetlink_subsystem *ss;
 171         int type, err;
 172
 173         /* All the messages must at least contain nfgenmsg */
 174         if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
 175                 return 0;
 176
 177         type = nlh->nlmsg_type;
 178 replay:
 179         rcu_read_lock();
 180         ss = nfnetlink_get_subsys(type);
 181         if (!ss) {
 182 #ifdef CONFIG_MODULES
 183                 rcu_read_unlock();
 184                 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
 185                 rcu_read_lock();
 186                 ss = nfnetlink_get_subsys(type);
 187                 if (!ss)
 188 #endif
 189                 {
 190                         rcu_read_unlock();
 191                         return -EINVAL;
 192                 }
 193         }
 194
 195         nc = nfnetlink_find_client(type, ss);
 196         if (!nc) {
 197                 rcu_read_unlock();
 198                 return -EINVAL;
 199         }
 200
 201         {
 202                 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 203                 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 204                 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 205                 struct nlattr *attr = (void *)nlh + min_len;
 206                 int attrlen = nlh->nlmsg_len - min_len;
 207                 __u8 subsys_id = NFNL_SUBSYS_ID(type);
 208
 209                 /* Sanity-check NFNL_MAX_ATTR_COUNT */
 210                 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 211                         rcu_read_unlock();
 212                         return -ENOMEM;
 213                 }
 214
 215                 err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
 216                                            attr, attrlen,
 217                                            ss->cb[cb_id].policy, extack);
 218                 if (err < 0) {
 219                         rcu_read_unlock();
 220                         return err;
 221                 }
 222
 223                 if (nc->call_rcu) {
 224                         err = nc->call_rcu(net, net->nfnl, skb, nlh,
 225                                            (const struct nlattr **)cda,
 226                                            extack);
 227                         rcu_read_unlock();
 228                 } else {
 229                         rcu_read_unlock();
 230                         nfnl_lock(subsys_id);
 231                         if (nfnl_dereference_protected(subsys_id) != ss ||
 232                             nfnetlink_find_client(type, ss) != nc)
 233                                 err = -EAGAIN;
 234                         else if (nc->call)
 235                                 err = nc->call(net, net->nfnl, skb, nlh,
 236                                                (const struct nlattr **)cda,
 237                                                extack);
 238                         else
 239                                 err = -EINVAL;
 240                         nfnl_unlock(subsys_id);
 241                 }
 242                 if (err == -EAGAIN)
 243                         goto replay;
 244                 return err;
 245         }
 246 }
 247
 248 struct nfnl_err {
 249         struct list_head        head;
 250         struct nlmsghdr         *nlh;
 251         int                     err;
 252         struct netlink_ext_ack  extack;
 253 };
 254
 255 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
 256                         const struct netlink_ext_ack *extack)
 257 {
 258         struct nfnl_err *nfnl_err;
 259
 260         nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
 261         if (nfnl_err == NULL)
 262                 return -ENOMEM;
 263
 264         nfnl_err->nlh = nlh;
 265         nfnl_err->err = err;
 266         nfnl_err->extack = *extack;
 267         list_add_tail(&nfnl_err->head, list);
 268
 269         return 0;
 270 }
 271
 272 static void nfnl_err_del(struct nfnl_err *nfnl_err)
 273 {
 274         list_del(&nfnl_err->head);
 275         kfree(nfnl_err);
 276 }
 277
 278 static void nfnl_err_reset(struct list_head *err_list)
 279 {
 280         struct nfnl_err *nfnl_err, *next;
 281
 282         list_for_each_entry_safe(nfnl_err, next, err_list, head)
 283                 nfnl_err_del(nfnl_err);
 284 }
 285
 286 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
 287 {
 288         struct nfnl_err *nfnl_err, *next;
 289
 290         list_for_each_entry_safe(nfnl_err, next, err_list, head) {
 291                 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
 292                             &nfnl_err->extack);
 293                 nfnl_err_del(nfnl_err);
 294         }
 295 }
 296
 297 enum {
 298         NFNL_BATCH_FAILURE      = (1 << 0),
 299         NFNL_BATCH_DONE         = (1 << 1),
 300         NFNL_BATCH_REPLAY       = (1 << 2),
 301 };
 302
 303 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
 304                                 u16 subsys_id, u32 genid)
 305 {
 306         struct sk_buff *oskb = skb;
 307         struct net *net = sock_net(skb->sk);
 308         const struct nfnetlink_subsystem *ss;
 309         const struct nfnl_callback *nc;
 310         struct netlink_ext_ack extack;
 311         LIST_HEAD(err_list);
 312         u32 status;
 313         int err;
 314
 315         if (subsys_id >= NFNL_SUBSYS_COUNT)
 316                 return netlink_ack(skb, nlh, -EINVAL, NULL);
 317 replay:
 318         status = 0;
 319
 320         skb = netlink_skb_clone(oskb, GFP_KERNEL);
 321         if (!skb)
 322                 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
 323
 324         nfnl_lock(subsys_id);
 325         ss = nfnl_dereference_protected(subsys_id);
 326         if (!ss) {
 327 #ifdef CONFIG_MODULES
 328                 nfnl_unlock(subsys_id);
 329                 request_module("nfnetlink-subsys-%d", subsys_id);
 330                 nfnl_lock(subsys_id);
 331                 ss = nfnl_dereference_protected(subsys_id);
 332                 if (!ss)
 333 #endif
 334                 {
 335                         nfnl_unlock(subsys_id);
 336                         netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 337                         return kfree_skb(skb);
 338                 }
 339         }
 340
 341         if (!ss->valid_genid || !ss->commit || !ss->abort) {
 342                 nfnl_unlock(subsys_id);
 343                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 344                 return kfree_skb(skb);
 345         }
 346
 347         if (!try_module_get(ss->owner)) {
 348                 nfnl_unlock(subsys_id);
 349                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 350                 return kfree_skb(skb);
 351         }
 352
 353         if (!ss->valid_genid(net, genid)) {
 354                 module_put(ss->owner);
 355                 nfnl_unlock(subsys_id);
 356                 netlink_ack(oskb, nlh, -ERESTART, NULL);
 357                 return kfree_skb(skb);
 358         }
 359
 360         nfnl_unlock(subsys_id);
 361
 362         while (skb->len >= nlmsg_total_size(0)) {
 363                 int msglen, type;
 364
 365                 if (fatal_signal_pending(current)) {
 366                         nfnl_err_reset(&err_list);
 367                         err = -EINTR;
 368                         status = NFNL_BATCH_FAILURE;
 369                         goto done;
 370                 }
 371
 372                 memset(&extack, 0, sizeof(extack));
 373                 nlh = nlmsg_hdr(skb);
 374                 err = 0;
 375
 376                 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
 377                     skb->len < nlh->nlmsg_len ||
 378                     nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
 379                         nfnl_err_reset(&err_list);
 380                         status |= NFNL_BATCH_FAILURE;
 381                         goto done;
 382                 }
 383
 384                 /* Only requests are handled by the kernel */
 385                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
 386                         err = -EINVAL;
 387                         goto ack;
 388                 }
 389
 390                 type = nlh->nlmsg_type;
 391                 if (type == NFNL_MSG_BATCH_BEGIN) {
 392                         /* Malformed: Batch begin twice */
 393                         nfnl_err_reset(&err_list);
 394                         status |= NFNL_BATCH_FAILURE;
 395                         goto done;
 396                 } else if (type == NFNL_MSG_BATCH_END) {
 397                         status |= NFNL_BATCH_DONE;
 398                         goto done;
 399                 } else if (type < NLMSG_MIN_TYPE) {
 400                         err = -EINVAL;
 401                         goto ack;
 402                 }
 403
 404                 /* We only accept a batch with messages for the same
 405                  * subsystem.
 406                  */
 407                 if (NFNL_SUBSYS_ID(type) != subsys_id) {
 408                         err = -EINVAL;
 409                         goto ack;
 410                 }
 411
 412                 nc = nfnetlink_find_client(type, ss);
 413                 if (!nc) {
 414                         err = -EINVAL;
 415                         goto ack;
 416                 }
 417
 418                 {
 419                         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 420                         u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 421                         struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 422                         struct nlattr *attr = (void *)nlh + min_len;
 423                         int attrlen = nlh->nlmsg_len - min_len;
 424
 425                         /* Sanity-check NFTA_MAX_ATTR */
 426                         if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 427                                 err = -ENOMEM;
 428                                 goto ack;
 429                         }
 430
 431                         err = nla_parse_deprecated(cda,
 432                                                    ss->cb[cb_id].attr_count,
 433                                                    attr, attrlen,
 434                                                    ss->cb[cb_id].policy, NULL);
 435                         if (err < 0)
 436                                 goto ack;
 437
 438                         if (nc->call_batch) {
 439                                 err = nc->call_batch(net, net->nfnl, skb, nlh,
 440                                                      (const struct nlattr **)cda,
 441                                                      &extack);
 442                         }
 443
 444                         /* The lock was released to autoload some module, we
 445                          * have to abort and start from scratch using the
 446                          * original skb.
 447                          */
 448                         if (err == -EAGAIN) {
 449                                 status |= NFNL_BATCH_REPLAY;
 450                                 goto done;
 451                         }
 452                 }
 453 ack:
 454                 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
 455                         /* Errors are delivered once the full batch has been
 456                          * processed, this avoids that the same error is
 457                          * reported several times when replaying the batch.
 458                          */
 459                         if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
 460                                 /* We failed to enqueue an error, reset the
 461                                  * list of errors and send OOM to userspace
 462                                  * pointing to the batch header.
 463                                  */
 464                                 nfnl_err_reset(&err_list);
 465                                 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
 466                                             NULL);
 467                                 status |= NFNL_BATCH_FAILURE;
 468                                 goto done;
 469                         }
 470                         /* We don't stop processing the batch on errors, thus,
 471                          * userspace gets all the errors that the batch
 472                          * triggers.
 473                          */
 474                         if (err)
 475                                 status |= NFNL_BATCH_FAILURE;
 476                 }
 477
 478                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 479                 if (msglen > skb->len)
 480                         msglen = skb->len;
 481                 skb_pull(skb, msglen);
 482         }
 483 done:
 484         if (status & NFNL_BATCH_REPLAY) {
 485                 ss->abort(net, oskb, true);
 486                 nfnl_err_reset(&err_list);
 487                 kfree_skb(skb);
 488                 module_put(ss->owner);
 489                 goto replay;
 490         } else if (status == NFNL_BATCH_DONE) {
 491                 err = ss->commit(net, oskb);
 492                 if (err == -EAGAIN) {
 493                         status |= NFNL_BATCH_REPLAY;
 494                         goto done;
 495                 } else if (err) {
 496                         ss->abort(net, oskb, false);
 497                         netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
 498                 }
 499         } else {
 500                 ss->abort(net, oskb, false);
 501         }
 502         if (ss->cleanup)
 503                 ss->cleanup(net);
 504
 505         nfnl_err_deliver(&err_list, oskb);
 506         kfree_skb(skb);
 507         module_put(ss->owner);
 508 }
 509
 510 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
 511         [NFNL_BATCH_GENID]      = { .type = NLA_U32 },
 512 };
 513
 514 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
 515 {
 516         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 517         struct nlattr *attr = (void *)nlh + min_len;
 518         struct nlattr *cda[NFNL_BATCH_MAX + 1];
 519         int attrlen = nlh->nlmsg_len - min_len;
 520         struct nfgenmsg *nfgenmsg;
 521         int msglen, err;
 522         u32 gen_id = 0;
 523         u16 res_id;
 524
 525         msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 526         if (msglen > skb->len)
 527                 msglen = skb->len;
 528
 529         if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
 530                 return;
 531
 532         err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
 533                                    nfnl_batch_policy, NULL);
 534         if (err < 0) {
 535                 netlink_ack(skb, nlh, err, NULL);
 536                 return;
 537         }
 538         if (cda[NFNL_BATCH_GENID])
 539                 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
 540
 541         nfgenmsg = nlmsg_data(nlh);
 542         skb_pull(skb, msglen);
 543         /* Work around old nft using host byte order */
 544         if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
 545                 res_id = NFNL_SUBSYS_NFTABLES;
 546         else
 547                 res_id = ntohs(nfgenmsg->res_id);
 548
 549         nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
 550 }
 551
 552 static void nfnetlink_rcv(struct sk_buff *skb)
 553 {
 554         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 555
 556         if (skb->len < NLMSG_HDRLEN ||
 557             nlh->nlmsg_len < NLMSG_HDRLEN ||
 558             skb->len < nlh->nlmsg_len)
 559                 return;
 560
 561         if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
 562                 netlink_ack(skb, nlh, -EPERM, NULL);
 563                 return;
 564         }
 565
 566         if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
 567                 nfnetlink_rcv_skb_batch(skb, nlh);
 568         else
 569                 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
 570 }
 571
 572 #ifdef CONFIG_MODULES
 573 static int nfnetlink_bind(struct net *net, int group)
 574 {
 575         const struct nfnetlink_subsystem *ss;
 576         int type;
 577
 578         if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
 579                 return 0;
 580
 581         type = nfnl_group2type[group];
 582
 583         rcu_read_lock();
 584         ss = nfnetlink_get_subsys(type << 8);
 585         rcu_read_unlock();
 586         if (!ss)
 587                 request_module_nowait("nfnetlink-subsys-%d", type);
 588         return 0;
 589 }
 590 #endif
 591
 592 static int __net_init nfnetlink_net_init(struct net *net)
 593 {
 594         struct sock *nfnl;
 595         struct netlink_kernel_cfg cfg = {
 596                 .groups = NFNLGRP_MAX,
 597                 .input  = nfnetlink_rcv,
 598 #ifdef CONFIG_MODULES
 599                 .bind   = nfnetlink_bind,
 600 #endif
 601         };
 602
 603         nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
 604         if (!nfnl)
 605                 return -ENOMEM;
 606         net->nfnl_stash = nfnl;
 607         rcu_assign_pointer(net->nfnl, nfnl);
 608         return 0;
 609 }
 610
 611 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
 612 {
 613         struct net *net;
 614
 615         list_for_each_entry(net, net_exit_list, exit_list)
 616                 RCU_INIT_POINTER(net->nfnl, NULL);
 617         synchronize_net();
 618         list_for_each_entry(net, net_exit_list, exit_list)
 619                 netlink_kernel_release(net->nfnl_stash);
 620 }
 621
 622 static struct pernet_operations nfnetlink_net_ops = {
 623         .init           = nfnetlink_net_init,
 624         .exit_batch     = nfnetlink_net_exit_batch,
 625 };
 626
 627 static int __init nfnetlink_init(void)
 628 {
 629         int i;
 630
 631         for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
 632                 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
 633
 634         for (i=0; i<NFNL_SUBSYS_COUNT; i++)
 635                 mutex_init(&table[i].mutex);
 636
 637         return register_pernet_subsys(&nfnetlink_net_ops);
 638 }
 639
 640 static void __exit nfnetlink_exit(void)
 641 {
 642         unregister_pernet_subsys(&nfnetlink_net_ops);
 643 }
 644 module_init(nfnetlink_init);
 645 module_exit(nfnetlink_exit);