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 struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT];
  50
  51 static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = {
  52         [NFNL_SUBSYS_NONE] = "nfnl_subsys_none",
  53         [NFNL_SUBSYS_CTNETLINK] = "nfnl_subsys_ctnetlink",
  54         [NFNL_SUBSYS_CTNETLINK_EXP] = "nfnl_subsys_ctnetlink_exp",
  55         [NFNL_SUBSYS_QUEUE] = "nfnl_subsys_queue",
  56         [NFNL_SUBSYS_ULOG] = "nfnl_subsys_ulog",
  57         [NFNL_SUBSYS_OSF] = "nfnl_subsys_osf",
  58         [NFNL_SUBSYS_IPSET] = "nfnl_subsys_ipset",
  59         [NFNL_SUBSYS_ACCT] = "nfnl_subsys_acct",
  60         [NFNL_SUBSYS_CTNETLINK_TIMEOUT] = "nfnl_subsys_cttimeout",
  61         [NFNL_SUBSYS_CTHELPER] = "nfnl_subsys_cthelper",
  62         [NFNL_SUBSYS_NFTABLES] = "nfnl_subsys_nftables",
  63         [NFNL_SUBSYS_NFT_COMPAT] = "nfnl_subsys_nftcompat",
  64 };
  65
  66 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
  67         [NFNLGRP_CONNTRACK_NEW]         = NFNL_SUBSYS_CTNETLINK,
  68         [NFNLGRP_CONNTRACK_UPDATE]      = NFNL_SUBSYS_CTNETLINK,
  69         [NFNLGRP_CONNTRACK_DESTROY]     = NFNL_SUBSYS_CTNETLINK,
  70         [NFNLGRP_CONNTRACK_EXP_NEW]     = NFNL_SUBSYS_CTNETLINK_EXP,
  71         [NFNLGRP_CONNTRACK_EXP_UPDATE]  = NFNL_SUBSYS_CTNETLINK_EXP,
  72         [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
  73         [NFNLGRP_NFTABLES]              = NFNL_SUBSYS_NFTABLES,
  74         [NFNLGRP_ACCT_QUOTA]            = NFNL_SUBSYS_ACCT,
  75         [NFNLGRP_NFTRACE]               = NFNL_SUBSYS_NFTABLES,
  76 };
  77
  78 void nfnl_lock(__u8 subsys_id)
  79 {
  80         mutex_lock(&table[subsys_id].mutex);
  81 }
  82 EXPORT_SYMBOL_GPL(nfnl_lock);
  83
  84 void nfnl_unlock(__u8 subsys_id)
  85 {
  86         mutex_unlock(&table[subsys_id].mutex);
  87 }
  88 EXPORT_SYMBOL_GPL(nfnl_unlock);
  89
  90 #ifdef CONFIG_PROVE_LOCKING
  91 bool lockdep_nfnl_is_held(u8 subsys_id)
  92 {
  93         return lockdep_is_held(&table[subsys_id].mutex);
  94 }
  95 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
  96 #endif
  97
  98 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
  99 {
 100         u8 cb_id;
 101
 102         /* Sanity-check attr_count size to avoid stack buffer overflow. */
 103         for (cb_id = 0; cb_id < n->cb_count; cb_id++)
 104                 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
 105                         return -EINVAL;
 106
 107         nfnl_lock(n->subsys_id);
 108         if (table[n->subsys_id].subsys) {
 109                 nfnl_unlock(n->subsys_id);
 110                 return -EBUSY;
 111         }
 112         rcu_assign_pointer(table[n->subsys_id].subsys, n);
 113         nfnl_unlock(n->subsys_id);
 114
 115         return 0;
 116 }
 117 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
 118
 119 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
 120 {
 121         nfnl_lock(n->subsys_id);
 122         table[n->subsys_id].subsys = NULL;
 123         nfnl_unlock(n->subsys_id);
 124         synchronize_rcu();
 125         return 0;
 126 }
 127 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
 128
 129 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
 130 {
 131         u8 subsys_id = NFNL_SUBSYS_ID(type);
 132
 133         if (subsys_id >= NFNL_SUBSYS_COUNT)
 134                 return NULL;
 135
 136         return rcu_dereference(table[subsys_id].subsys);
 137 }
 138
 139 static inline const struct nfnl_callback *
 140 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
 141 {
 142         u8 cb_id = NFNL_MSG_TYPE(type);
 143
 144         if (cb_id >= ss->cb_count)
 145                 return NULL;
 146
 147         return &ss->cb[cb_id];
 148 }
 149
 150 int nfnetlink_has_listeners(struct net *net, unsigned int group)
 151 {
 152         return netlink_has_listeners(net->nfnl, group);
 153 }
 154 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
 155
 156 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
 157                    unsigned int group, int echo, gfp_t flags)
 158 {
 159         return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
 160 }
 161 EXPORT_SYMBOL_GPL(nfnetlink_send);
 162
 163 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
 164 {
 165         return netlink_set_err(net->nfnl, portid, group, error);
 166 }
 167 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
 168
 169 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
 170 {
 171         int err;
 172
 173         err = nlmsg_unicast(net->nfnl, skb, portid);
 174         if (err == -EAGAIN)
 175                 err = -ENOBUFS;
 176
 177         return err;
 178 }
 179 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
 180
 181 /* Process one complete nfnetlink message. */
 182 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 183                              struct netlink_ext_ack *extack)
 184 {
 185         struct net *net = sock_net(skb->sk);
 186         const struct nfnl_callback *nc;
 187         const struct nfnetlink_subsystem *ss;
 188         int type, err;
 189
 190         /* All the messages must at least contain nfgenmsg */
 191         if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
 192                 return 0;
 193
 194         type = nlh->nlmsg_type;
 195 replay:
 196         rcu_read_lock();
 197         ss = nfnetlink_get_subsys(type);
 198         if (!ss) {
 199 #ifdef CONFIG_MODULES
 200                 rcu_read_unlock();
 201                 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
 202                 rcu_read_lock();
 203                 ss = nfnetlink_get_subsys(type);
 204                 if (!ss)
 205 #endif
 206                 {
 207                         rcu_read_unlock();
 208                         return -EINVAL;
 209                 }
 210         }
 211
 212         nc = nfnetlink_find_client(type, ss);
 213         if (!nc) {
 214                 rcu_read_unlock();
 215                 return -EINVAL;
 216         }
 217
 218         {
 219                 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 220                 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 221                 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 222                 struct nlattr *attr = (void *)nlh + min_len;
 223                 int attrlen = nlh->nlmsg_len - min_len;
 224                 __u8 subsys_id = NFNL_SUBSYS_ID(type);
 225
 226                 /* Sanity-check NFNL_MAX_ATTR_COUNT */
 227                 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 228                         rcu_read_unlock();
 229                         return -ENOMEM;
 230                 }
 231
 232                 err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
 233                                            attr, attrlen,
 234                                            ss->cb[cb_id].policy, extack);
 235                 if (err < 0) {
 236                         rcu_read_unlock();
 237                         return err;
 238                 }
 239
 240                 if (nc->call_rcu) {
 241                         err = nc->call_rcu(net, net->nfnl, skb, nlh,
 242                                            (const struct nlattr **)cda,
 243                                            extack);
 244                         rcu_read_unlock();
 245                 } else {
 246                         rcu_read_unlock();
 247                         nfnl_lock(subsys_id);
 248                         if (nfnl_dereference_protected(subsys_id) != ss ||
 249                             nfnetlink_find_client(type, ss) != nc)
 250                                 err = -EAGAIN;
 251                         else if (nc->call)
 252                                 err = nc->call(net, net->nfnl, skb, nlh,
 253                                                (const struct nlattr **)cda,
 254                                                extack);
 255                         else
 256                                 err = -EINVAL;
 257                         nfnl_unlock(subsys_id);
 258                 }
 259                 if (err == -EAGAIN)
 260                         goto replay;
 261                 return err;
 262         }
 263 }
 264
 265 struct nfnl_err {
 266         struct list_head        head;
 267         struct nlmsghdr         *nlh;
 268         int                     err;
 269         struct netlink_ext_ack  extack;
 270 };
 271
 272 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
 273                         const struct netlink_ext_ack *extack)
 274 {
 275         struct nfnl_err *nfnl_err;
 276
 277         nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
 278         if (nfnl_err == NULL)
 279                 return -ENOMEM;
 280
 281         nfnl_err->nlh = nlh;
 282         nfnl_err->err = err;
 283         nfnl_err->extack = *extack;
 284         list_add_tail(&nfnl_err->head, list);
 285
 286         return 0;
 287 }
 288
 289 static void nfnl_err_del(struct nfnl_err *nfnl_err)
 290 {
 291         list_del(&nfnl_err->head);
 292         kfree(nfnl_err);
 293 }
 294
 295 static void nfnl_err_reset(struct list_head *err_list)
 296 {
 297         struct nfnl_err *nfnl_err, *next;
 298
 299         list_for_each_entry_safe(nfnl_err, next, err_list, head)
 300                 nfnl_err_del(nfnl_err);
 301 }
 302
 303 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
 304 {
 305         struct nfnl_err *nfnl_err, *next;
 306
 307         list_for_each_entry_safe(nfnl_err, next, err_list, head) {
 308                 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
 309                             &nfnl_err->extack);
 310                 nfnl_err_del(nfnl_err);
 311         }
 312 }
 313
 314 enum {
 315         NFNL_BATCH_FAILURE      = (1 << 0),
 316         NFNL_BATCH_DONE         = (1 << 1),
 317         NFNL_BATCH_REPLAY       = (1 << 2),
 318 };
 319
 320 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
 321                                 u16 subsys_id, u32 genid)
 322 {
 323         struct sk_buff *oskb = skb;
 324         struct net *net = sock_net(skb->sk);
 325         const struct nfnetlink_subsystem *ss;
 326         const struct nfnl_callback *nc;
 327         struct netlink_ext_ack extack;
 328         LIST_HEAD(err_list);
 329         u32 status;
 330         int err;
 331
 332         if (subsys_id >= NFNL_SUBSYS_COUNT)
 333                 return netlink_ack(skb, nlh, -EINVAL, NULL);
 334 replay:
 335         status = 0;
 336 replay_abort:
 337         skb = netlink_skb_clone(oskb, GFP_KERNEL);
 338         if (!skb)
 339                 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
 340
 341         nfnl_lock(subsys_id);
 342         ss = nfnl_dereference_protected(subsys_id);
 343         if (!ss) {
 344 #ifdef CONFIG_MODULES
 345                 nfnl_unlock(subsys_id);
 346                 request_module("nfnetlink-subsys-%d", subsys_id);
 347                 nfnl_lock(subsys_id);
 348                 ss = nfnl_dereference_protected(subsys_id);
 349                 if (!ss)
 350 #endif
 351                 {
 352                         nfnl_unlock(subsys_id);
 353                         netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 354                         return kfree_skb(skb);
 355                 }
 356         }
 357
 358         if (!ss->valid_genid || !ss->commit || !ss->abort) {
 359                 nfnl_unlock(subsys_id);
 360                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 361                 return kfree_skb(skb);
 362         }
 363
 364         if (!try_module_get(ss->owner)) {
 365                 nfnl_unlock(subsys_id);
 366                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 367                 return kfree_skb(skb);
 368         }
 369
 370         if (!ss->valid_genid(net, genid)) {
 371                 module_put(ss->owner);
 372                 nfnl_unlock(subsys_id);
 373                 netlink_ack(oskb, nlh, -ERESTART, NULL);
 374                 return kfree_skb(skb);
 375         }
 376
 377         nfnl_unlock(subsys_id);
 378
 379         while (skb->len >= nlmsg_total_size(0)) {
 380                 int msglen, type;
 381
 382                 if (fatal_signal_pending(current)) {
 383                         nfnl_err_reset(&err_list);
 384                         err = -EINTR;
 385                         status = NFNL_BATCH_FAILURE;
 386                         goto done;
 387                 }
 388
 389                 memset(&extack, 0, sizeof(extack));
 390                 nlh = nlmsg_hdr(skb);
 391                 err = 0;
 392
 393                 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
 394                     skb->len < nlh->nlmsg_len ||
 395                     nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
 396                         nfnl_err_reset(&err_list);
 397                         status |= NFNL_BATCH_FAILURE;
 398                         goto done;
 399                 }
 400
 401                 /* Only requests are handled by the kernel */
 402                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
 403                         err = -EINVAL;
 404                         goto ack;
 405                 }
 406
 407                 type = nlh->nlmsg_type;
 408                 if (type == NFNL_MSG_BATCH_BEGIN) {
 409                         /* Malformed: Batch begin twice */
 410                         nfnl_err_reset(&err_list);
 411                         status |= NFNL_BATCH_FAILURE;
 412                         goto done;
 413                 } else if (type == NFNL_MSG_BATCH_END) {
 414                         status |= NFNL_BATCH_DONE;
 415                         goto done;
 416                 } else if (type < NLMSG_MIN_TYPE) {
 417                         err = -EINVAL;
 418                         goto ack;
 419                 }
 420
 421                 /* We only accept a batch with messages for the same
 422                  * subsystem.
 423                  */
 424                 if (NFNL_SUBSYS_ID(type) != subsys_id) {
 425                         err = -EINVAL;
 426                         goto ack;
 427                 }
 428
 429                 nc = nfnetlink_find_client(type, ss);
 430                 if (!nc) {
 431                         err = -EINVAL;
 432                         goto ack;
 433                 }
 434
 435                 {
 436                         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 437                         u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 438                         struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 439                         struct nlattr *attr = (void *)nlh + min_len;
 440                         int attrlen = nlh->nlmsg_len - min_len;
 441
 442                         /* Sanity-check NFTA_MAX_ATTR */
 443                         if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 444                                 err = -ENOMEM;
 445                                 goto ack;
 446                         }
 447
 448                         err = nla_parse_deprecated(cda,
 449                                                    ss->cb[cb_id].attr_count,
 450                                                    attr, attrlen,
 451                                                    ss->cb[cb_id].policy, NULL);
 452                         if (err < 0)
 453                                 goto ack;
 454
 455                         if (nc->call_batch) {
 456                                 err = nc->call_batch(net, net->nfnl, skb, nlh,
 457                                                      (const struct nlattr **)cda,
 458                                                      &extack);
 459                         }
 460
 461                         /* The lock was released to autoload some module, we
 462                          * have to abort and start from scratch using the
 463                          * original skb.
 464                          */
 465                         if (err == -EAGAIN) {
 466                                 status |= NFNL_BATCH_REPLAY;
 467                                 goto done;
 468                         }
 469                 }
 470 ack:
 471                 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
 472                         /* Errors are delivered once the full batch has been
 473                          * processed, this avoids that the same error is
 474                          * reported several times when replaying the batch.
 475                          */
 476                         if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
 477                                 /* We failed to enqueue an error, reset the
 478                                  * list of errors and send OOM to userspace
 479                                  * pointing to the batch header.
 480                                  */
 481                                 nfnl_err_reset(&err_list);
 482                                 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
 483                                             NULL);
 484                                 status |= NFNL_BATCH_FAILURE;
 485                                 goto done;
 486                         }
 487                         /* We don't stop processing the batch on errors, thus,
 488                          * userspace gets all the errors that the batch
 489                          * triggers.
 490                          */
 491                         if (err)
 492                                 status |= NFNL_BATCH_FAILURE;
 493                 }
 494
 495                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 496                 if (msglen > skb->len)
 497                         msglen = skb->len;
 498                 skb_pull(skb, msglen);
 499         }
 500 done:
 501         if (status & NFNL_BATCH_REPLAY) {
 502                 ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
 503                 nfnl_err_reset(&err_list);
 504                 kfree_skb(skb);
 505                 module_put(ss->owner);
 506                 goto replay;
 507         } else if (status == NFNL_BATCH_DONE) {
 508                 err = ss->commit(net, oskb);
 509                 if (err == -EAGAIN) {
 510                         status |= NFNL_BATCH_REPLAY;
 511                         goto done;
 512                 } else if (err) {
 513                         ss->abort(net, oskb, NFNL_ABORT_NONE);
 514                         netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
 515                 }
 516         } else {
 517                 enum nfnl_abort_action abort_action;
 518
 519                 if (status & NFNL_BATCH_FAILURE)
 520                         abort_action = NFNL_ABORT_NONE;
 521                 else
 522                         abort_action = NFNL_ABORT_VALIDATE;
 523
 524                 err = ss->abort(net, oskb, abort_action);
 525                 if (err == -EAGAIN) {
 526                         nfnl_err_reset(&err_list);
 527                         kfree_skb(skb);
 528                         module_put(ss->owner);
 529                         status |= NFNL_BATCH_FAILURE;
 530                         goto replay_abort;
 531                 }
 532         }
 533         if (ss->cleanup)
 534                 ss->cleanup(net);
 535
 536         nfnl_err_deliver(&err_list, oskb);
 537         kfree_skb(skb);
 538         module_put(ss->owner);
 539 }
 540
 541 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
 542         [NFNL_BATCH_GENID]      = { .type = NLA_U32 },
 543 };
 544
 545 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
 546 {
 547         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 548         struct nlattr *attr = (void *)nlh + min_len;
 549         struct nlattr *cda[NFNL_BATCH_MAX + 1];
 550         int attrlen = nlh->nlmsg_len - min_len;
 551         struct nfgenmsg *nfgenmsg;
 552         int msglen, err;
 553         u32 gen_id = 0;
 554         u16 res_id;
 555
 556         msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 557         if (msglen > skb->len)
 558                 msglen = skb->len;
 559
 560         if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
 561                 return;
 562
 563         err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
 564                                    nfnl_batch_policy, NULL);
 565         if (err < 0) {
 566                 netlink_ack(skb, nlh, err, NULL);
 567                 return;
 568         }
 569         if (cda[NFNL_BATCH_GENID])
 570                 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
 571
 572         nfgenmsg = nlmsg_data(nlh);
 573         skb_pull(skb, msglen);
 574         /* Work around old nft using host byte order */
 575         if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
 576                 res_id = NFNL_SUBSYS_NFTABLES;
 577         else
 578                 res_id = ntohs(nfgenmsg->res_id);
 579
 580         nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
 581 }
 582
 583 static void nfnetlink_rcv(struct sk_buff *skb)
 584 {
 585         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 586
 587         if (skb->len < NLMSG_HDRLEN ||
 588             nlh->nlmsg_len < NLMSG_HDRLEN ||
 589             skb->len < nlh->nlmsg_len)
 590                 return;
 591
 592         if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
 593                 netlink_ack(skb, nlh, -EPERM, NULL);
 594                 return;
 595         }
 596
 597         if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
 598                 nfnetlink_rcv_skb_batch(skb, nlh);
 599         else
 600                 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
 601 }
 602
 603 #ifdef CONFIG_MODULES
 604 static int nfnetlink_bind(struct net *net, int group)
 605 {
 606         const struct nfnetlink_subsystem *ss;
 607         int type;
 608
 609         if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
 610                 return 0;
 611
 612         type = nfnl_group2type[group];
 613
 614         rcu_read_lock();
 615         ss = nfnetlink_get_subsys(type << 8);
 616         rcu_read_unlock();
 617         if (!ss)
 618                 request_module_nowait("nfnetlink-subsys-%d", type);
 619         return 0;
 620 }
 621 #endif
 622
 623 static int __net_init nfnetlink_net_init(struct net *net)
 624 {
 625         struct sock *nfnl;
 626         struct netlink_kernel_cfg cfg = {
 627                 .groups = NFNLGRP_MAX,
 628                 .input  = nfnetlink_rcv,
 629 #ifdef CONFIG_MODULES
 630                 .bind   = nfnetlink_bind,
 631 #endif
 632         };
 633
 634         nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
 635         if (!nfnl)
 636                 return -ENOMEM;
 637         net->nfnl_stash = nfnl;
 638         rcu_assign_pointer(net->nfnl, nfnl);
 639         return 0;
 640 }
 641
 642 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
 643 {
 644         struct net *net;
 645
 646         list_for_each_entry(net, net_exit_list, exit_list)
 647                 RCU_INIT_POINTER(net->nfnl, NULL);
 648         synchronize_net();
 649         list_for_each_entry(net, net_exit_list, exit_list)
 650                 netlink_kernel_release(net->nfnl_stash);
 651 }
 652
 653 static struct pernet_operations nfnetlink_net_ops = {
 654         .init           = nfnetlink_net_init,
 655         .exit_batch     = nfnetlink_net_exit_batch,
 656 };
 657
 658 static int __init nfnetlink_init(void)
 659 {
 660         int i;
 661
 662         for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
 663                 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
 664
 665         for (i=0; i<NFNL_SUBSYS_COUNT; i++)
 666                 __mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
 667
 668         return register_pernet_subsys(&nfnetlink_net_ops);
 669 }
 670
 671 static void __exit nfnetlink_exit(void)
 672 {
 673         unregister_pernet_subsys(&nfnetlink_net_ops);
 674 }
 675 module_init(nfnetlink_init);
 676 module_exit(nfnetlink_exit);