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 <net/netns/generic.h>
  32 #include <linux/netfilter/nfnetlink.h>
  33
  34 MODULE_LICENSE("GPL");
  35 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  36 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
  37 MODULE_DESCRIPTION("Netfilter messages via netlink socket");
  38
  39 #define nfnl_dereference_protected(id) \
  40         rcu_dereference_protected(table[(id)].subsys, \
  41                                   lockdep_nfnl_is_held((id)))
  42
  43 #define NFNL_MAX_ATTR_COUNT     32
  44
  45 static unsigned int nfnetlink_pernet_id __read_mostly;
  46
  47 struct nfnl_net {
  48         struct sock *nfnl;
  49 };
  50
  51 static struct {
  52         struct mutex                            mutex;
  53         const struct nfnetlink_subsystem __rcu  *subsys;
  54 } table[NFNL_SUBSYS_COUNT];
  55
  56 static struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT];
  57
  58 static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = {
  59         [NFNL_SUBSYS_NONE] = "nfnl_subsys_none",
  60         [NFNL_SUBSYS_CTNETLINK] = "nfnl_subsys_ctnetlink",
  61         [NFNL_SUBSYS_CTNETLINK_EXP] = "nfnl_subsys_ctnetlink_exp",
  62         [NFNL_SUBSYS_QUEUE] = "nfnl_subsys_queue",
  63         [NFNL_SUBSYS_ULOG] = "nfnl_subsys_ulog",
  64         [NFNL_SUBSYS_OSF] = "nfnl_subsys_osf",
  65         [NFNL_SUBSYS_IPSET] = "nfnl_subsys_ipset",
  66         [NFNL_SUBSYS_ACCT] = "nfnl_subsys_acct",
  67         [NFNL_SUBSYS_CTNETLINK_TIMEOUT] = "nfnl_subsys_cttimeout",
  68         [NFNL_SUBSYS_CTHELPER] = "nfnl_subsys_cthelper",
  69         [NFNL_SUBSYS_NFTABLES] = "nfnl_subsys_nftables",
  70         [NFNL_SUBSYS_NFT_COMPAT] = "nfnl_subsys_nftcompat",
  71 };
  72
  73 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
  74         [NFNLGRP_CONNTRACK_NEW]         = NFNL_SUBSYS_CTNETLINK,
  75         [NFNLGRP_CONNTRACK_UPDATE]      = NFNL_SUBSYS_CTNETLINK,
  76         [NFNLGRP_CONNTRACK_DESTROY]     = NFNL_SUBSYS_CTNETLINK,
  77         [NFNLGRP_CONNTRACK_EXP_NEW]     = NFNL_SUBSYS_CTNETLINK_EXP,
  78         [NFNLGRP_CONNTRACK_EXP_UPDATE]  = NFNL_SUBSYS_CTNETLINK_EXP,
  79         [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
  80         [NFNLGRP_NFTABLES]              = NFNL_SUBSYS_NFTABLES,
  81         [NFNLGRP_ACCT_QUOTA]            = NFNL_SUBSYS_ACCT,
  82         [NFNLGRP_NFTRACE]               = NFNL_SUBSYS_NFTABLES,
  83 };
  84
  85 static struct nfnl_net *nfnl_pernet(struct net *net)
  86 {
  87         return net_generic(net, nfnetlink_pernet_id);
  88 }
  89
  90 void nfnl_lock(__u8 subsys_id)
  91 {
  92         mutex_lock(&table[subsys_id].mutex);
  93 }
  94 EXPORT_SYMBOL_GPL(nfnl_lock);
  95
  96 void nfnl_unlock(__u8 subsys_id)
  97 {
  98         mutex_unlock(&table[subsys_id].mutex);
  99 }
 100 EXPORT_SYMBOL_GPL(nfnl_unlock);
 101
 102 #ifdef CONFIG_PROVE_LOCKING
 103 bool lockdep_nfnl_is_held(u8 subsys_id)
 104 {
 105         return lockdep_is_held(&table[subsys_id].mutex);
 106 }
 107 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
 108 #endif
 109
 110 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
 111 {
 112         u8 cb_id;
 113
 114         /* Sanity-check attr_count size to avoid stack buffer overflow. */
 115         for (cb_id = 0; cb_id < n->cb_count; cb_id++)
 116                 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
 117                         return -EINVAL;
 118
 119         nfnl_lock(n->subsys_id);
 120         if (table[n->subsys_id].subsys) {
 121                 nfnl_unlock(n->subsys_id);
 122                 return -EBUSY;
 123         }
 124         rcu_assign_pointer(table[n->subsys_id].subsys, n);
 125         nfnl_unlock(n->subsys_id);
 126
 127         return 0;
 128 }
 129 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
 130
 131 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
 132 {
 133         nfnl_lock(n->subsys_id);
 134         table[n->subsys_id].subsys = NULL;
 135         nfnl_unlock(n->subsys_id);
 136         synchronize_rcu();
 137         return 0;
 138 }
 139 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
 140
 141 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
 142 {
 143         u8 subsys_id = NFNL_SUBSYS_ID(type);
 144
 145         if (subsys_id >= NFNL_SUBSYS_COUNT)
 146                 return NULL;
 147
 148         return rcu_dereference(table[subsys_id].subsys);
 149 }
 150
 151 static inline const struct nfnl_callback *
 152 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
 153 {
 154         u8 cb_id = NFNL_MSG_TYPE(type);
 155
 156         if (cb_id >= ss->cb_count)
 157                 return NULL;
 158
 159         return &ss->cb[cb_id];
 160 }
 161
 162 int nfnetlink_has_listeners(struct net *net, unsigned int group)
 163 {
 164         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 165
 166         return netlink_has_listeners(nfnlnet->nfnl, group);
 167 }
 168 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
 169
 170 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
 171                    unsigned int group, int echo, gfp_t flags)
 172 {
 173         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 174
 175         return nlmsg_notify(nfnlnet->nfnl, skb, portid, group, echo, flags);
 176 }
 177 EXPORT_SYMBOL_GPL(nfnetlink_send);
 178
 179 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
 180 {
 181         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 182
 183         return netlink_set_err(nfnlnet->nfnl, portid, group, error);
 184 }
 185 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
 186
 187 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
 188 {
 189         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 190         int err;
 191
 192         err = nlmsg_unicast(nfnlnet->nfnl, skb, portid);
 193         if (err == -EAGAIN)
 194                 err = -ENOBUFS;
 195
 196         return err;
 197 }
 198 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
 199
 200 void nfnetlink_broadcast(struct net *net, struct sk_buff *skb, __u32 portid,
 201                          __u32 group, gfp_t allocation)
 202 {
 203         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 204
 205         netlink_broadcast(nfnlnet->nfnl, skb, portid, group, allocation);
 206 }
 207 EXPORT_SYMBOL_GPL(nfnetlink_broadcast);
 208
 209 /* Process one complete nfnetlink message. */
 210 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 211                              struct netlink_ext_ack *extack)
 212 {
 213         struct net *net = sock_net(skb->sk);
 214         const struct nfnl_callback *nc;
 215         const struct nfnetlink_subsystem *ss;
 216         int type, err;
 217
 218         /* All the messages must at least contain nfgenmsg */
 219         if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
 220                 return 0;
 221
 222         type = nlh->nlmsg_type;
 223 replay:
 224         rcu_read_lock();
 225
 226         ss = nfnetlink_get_subsys(type);
 227         if (!ss) {
 228 #ifdef CONFIG_MODULES
 229                 rcu_read_unlock();
 230                 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
 231                 rcu_read_lock();
 232                 ss = nfnetlink_get_subsys(type);
 233                 if (!ss)
 234 #endif
 235                 {
 236                         rcu_read_unlock();
 237                         return -EINVAL;
 238                 }
 239         }
 240
 241         nc = nfnetlink_find_client(type, ss);
 242         if (!nc) {
 243                 rcu_read_unlock();
 244                 return -EINVAL;
 245         }
 246
 247         {
 248                 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 249                 struct nfnl_net *nfnlnet = nfnl_pernet(net);
 250                 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 251                 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 252                 struct nlattr *attr = (void *)nlh + min_len;
 253                 int attrlen = nlh->nlmsg_len - min_len;
 254                 __u8 subsys_id = NFNL_SUBSYS_ID(type);
 255
 256                 /* Sanity-check NFNL_MAX_ATTR_COUNT */
 257                 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 258                         rcu_read_unlock();
 259                         return -ENOMEM;
 260                 }
 261
 262                 err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
 263                                            attr, attrlen,
 264                                            ss->cb[cb_id].policy, extack);
 265                 if (err < 0) {
 266                         rcu_read_unlock();
 267                         return err;
 268                 }
 269
 270                 if (nc->call_rcu) {
 271                         err = nc->call_rcu(net, nfnlnet->nfnl, skb, nlh,
 272                                            (const struct nlattr **)cda,
 273                                            extack);
 274                         rcu_read_unlock();
 275                 } else {
 276                         rcu_read_unlock();
 277                         nfnl_lock(subsys_id);
 278                         if (nfnl_dereference_protected(subsys_id) != ss ||
 279                             nfnetlink_find_client(type, ss) != nc)
 280                                 err = -EAGAIN;
 281                         else if (nc->call)
 282                                 err = nc->call(net, nfnlnet->nfnl, skb, nlh,
 283                                                (const struct nlattr **)cda,
 284                                                extack);
 285                         else
 286                                 err = -EINVAL;
 287                         nfnl_unlock(subsys_id);
 288                 }
 289                 if (err == -EAGAIN)
 290                         goto replay;
 291                 return err;
 292         }
 293 }
 294
 295 struct nfnl_err {
 296         struct list_head        head;
 297         struct nlmsghdr         *nlh;
 298         int                     err;
 299         struct netlink_ext_ack  extack;
 300 };
 301
 302 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
 303                         const struct netlink_ext_ack *extack)
 304 {
 305         struct nfnl_err *nfnl_err;
 306
 307         nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
 308         if (nfnl_err == NULL)
 309                 return -ENOMEM;
 310
 311         nfnl_err->nlh = nlh;
 312         nfnl_err->err = err;
 313         nfnl_err->extack = *extack;
 314         list_add_tail(&nfnl_err->head, list);
 315
 316         return 0;
 317 }
 318
 319 static void nfnl_err_del(struct nfnl_err *nfnl_err)
 320 {
 321         list_del(&nfnl_err->head);
 322         kfree(nfnl_err);
 323 }
 324
 325 static void nfnl_err_reset(struct list_head *err_list)
 326 {
 327         struct nfnl_err *nfnl_err, *next;
 328
 329         list_for_each_entry_safe(nfnl_err, next, err_list, head)
 330                 nfnl_err_del(nfnl_err);
 331 }
 332
 333 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
 334 {
 335         struct nfnl_err *nfnl_err, *next;
 336
 337         list_for_each_entry_safe(nfnl_err, next, err_list, head) {
 338                 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
 339                             &nfnl_err->extack);
 340                 nfnl_err_del(nfnl_err);
 341         }
 342 }
 343
 344 enum {
 345         NFNL_BATCH_FAILURE      = (1 << 0),
 346         NFNL_BATCH_DONE         = (1 << 1),
 347         NFNL_BATCH_REPLAY       = (1 << 2),
 348 };
 349
 350 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
 351                                 u16 subsys_id, u32 genid)
 352 {
 353         struct sk_buff *oskb = skb;
 354         struct net *net = sock_net(skb->sk);
 355         const struct nfnetlink_subsystem *ss;
 356         const struct nfnl_callback *nc;
 357         struct netlink_ext_ack extack;
 358         LIST_HEAD(err_list);
 359         u32 status;
 360         int err;
 361
 362         if (subsys_id >= NFNL_SUBSYS_COUNT)
 363                 return netlink_ack(skb, nlh, -EINVAL, NULL);
 364 replay:
 365         status = 0;
 366 replay_abort:
 367         skb = netlink_skb_clone(oskb, GFP_KERNEL);
 368         if (!skb)
 369                 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
 370
 371         nfnl_lock(subsys_id);
 372         ss = nfnl_dereference_protected(subsys_id);
 373         if (!ss) {
 374 #ifdef CONFIG_MODULES
 375                 nfnl_unlock(subsys_id);
 376                 request_module("nfnetlink-subsys-%d", subsys_id);
 377                 nfnl_lock(subsys_id);
 378                 ss = nfnl_dereference_protected(subsys_id);
 379                 if (!ss)
 380 #endif
 381                 {
 382                         nfnl_unlock(subsys_id);
 383                         netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 384                         return kfree_skb(skb);
 385                 }
 386         }
 387
 388         if (!ss->valid_genid || !ss->commit || !ss->abort) {
 389                 nfnl_unlock(subsys_id);
 390                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 391                 return kfree_skb(skb);
 392         }
 393
 394         if (!try_module_get(ss->owner)) {
 395                 nfnl_unlock(subsys_id);
 396                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 397                 return kfree_skb(skb);
 398         }
 399
 400         if (!ss->valid_genid(net, genid)) {
 401                 module_put(ss->owner);
 402                 nfnl_unlock(subsys_id);
 403                 netlink_ack(oskb, nlh, -ERESTART, NULL);
 404                 return kfree_skb(skb);
 405         }
 406
 407         nfnl_unlock(subsys_id);
 408
 409         while (skb->len >= nlmsg_total_size(0)) {
 410                 int msglen, type;
 411
 412                 if (fatal_signal_pending(current)) {
 413                         nfnl_err_reset(&err_list);
 414                         err = -EINTR;
 415                         status = NFNL_BATCH_FAILURE;
 416                         goto done;
 417                 }
 418
 419                 memset(&extack, 0, sizeof(extack));
 420                 nlh = nlmsg_hdr(skb);
 421                 err = 0;
 422
 423                 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
 424                     skb->len < nlh->nlmsg_len ||
 425                     nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
 426                         nfnl_err_reset(&err_list);
 427                         status |= NFNL_BATCH_FAILURE;
 428                         goto done;
 429                 }
 430
 431                 /* Only requests are handled by the kernel */
 432                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
 433                         err = -EINVAL;
 434                         goto ack;
 435                 }
 436
 437                 type = nlh->nlmsg_type;
 438                 if (type == NFNL_MSG_BATCH_BEGIN) {
 439                         /* Malformed: Batch begin twice */
 440                         nfnl_err_reset(&err_list);
 441                         status |= NFNL_BATCH_FAILURE;
 442                         goto done;
 443                 } else if (type == NFNL_MSG_BATCH_END) {
 444                         status |= NFNL_BATCH_DONE;
 445                         goto done;
 446                 } else if (type < NLMSG_MIN_TYPE) {
 447                         err = -EINVAL;
 448                         goto ack;
 449                 }
 450
 451                 /* We only accept a batch with messages for the same
 452                  * subsystem.
 453                  */
 454                 if (NFNL_SUBSYS_ID(type) != subsys_id) {
 455                         err = -EINVAL;
 456                         goto ack;
 457                 }
 458
 459                 nc = nfnetlink_find_client(type, ss);
 460                 if (!nc) {
 461                         err = -EINVAL;
 462                         goto ack;
 463                 }
 464
 465                 {
 466                         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 467                         u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
 468                         struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
 469                         struct nlattr *attr = (void *)nlh + min_len;
 470                         int attrlen = nlh->nlmsg_len - min_len;
 471
 472                         /* Sanity-check NFTA_MAX_ATTR */
 473                         if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
 474                                 err = -ENOMEM;
 475                                 goto ack;
 476                         }
 477
 478                         err = nla_parse_deprecated(cda,
 479                                                    ss->cb[cb_id].attr_count,
 480                                                    attr, attrlen,
 481                                                    ss->cb[cb_id].policy, NULL);
 482                         if (err < 0)
 483                                 goto ack;
 484
 485                         if (nc->call_batch) {
 486                                 struct nfnl_net *nfnlnet = nfnl_pernet(net);
 487
 488                                 err = nc->call_batch(net, nfnlnet->nfnl, skb, nlh,
 489                                                      (const struct nlattr **)cda,
 490                                                      &extack);
 491                         }
 492
 493                         /* The lock was released to autoload some module, we
 494                          * have to abort and start from scratch using the
 495                          * original skb.
 496                          */
 497                         if (err == -EAGAIN) {
 498                                 status |= NFNL_BATCH_REPLAY;
 499                                 goto done;
 500                         }
 501                 }
 502 ack:
 503                 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
 504                         /* Errors are delivered once the full batch has been
 505                          * processed, this avoids that the same error is
 506                          * reported several times when replaying the batch.
 507                          */
 508                         if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
 509                                 /* We failed to enqueue an error, reset the
 510                                  * list of errors and send OOM to userspace
 511                                  * pointing to the batch header.
 512                                  */
 513                                 nfnl_err_reset(&err_list);
 514                                 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
 515                                             NULL);
 516                                 status |= NFNL_BATCH_FAILURE;
 517                                 goto done;
 518                         }
 519                         /* We don't stop processing the batch on errors, thus,
 520                          * userspace gets all the errors that the batch
 521                          * triggers.
 522                          */
 523                         if (err)
 524                                 status |= NFNL_BATCH_FAILURE;
 525                 }
 526
 527                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 528                 if (msglen > skb->len)
 529                         msglen = skb->len;
 530                 skb_pull(skb, msglen);
 531         }
 532 done:
 533         if (status & NFNL_BATCH_REPLAY) {
 534                 ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
 535                 nfnl_err_reset(&err_list);
 536                 kfree_skb(skb);
 537                 module_put(ss->owner);
 538                 goto replay;
 539         } else if (status == NFNL_BATCH_DONE) {
 540                 err = ss->commit(net, oskb);
 541                 if (err == -EAGAIN) {
 542                         status |= NFNL_BATCH_REPLAY;
 543                         goto done;
 544                 } else if (err) {
 545                         ss->abort(net, oskb, NFNL_ABORT_NONE);
 546                         netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
 547                 }
 548         } else {
 549                 enum nfnl_abort_action abort_action;
 550
 551                 if (status & NFNL_BATCH_FAILURE)
 552                         abort_action = NFNL_ABORT_NONE;
 553                 else
 554                         abort_action = NFNL_ABORT_VALIDATE;
 555
 556                 err = ss->abort(net, oskb, abort_action);
 557                 if (err == -EAGAIN) {
 558                         nfnl_err_reset(&err_list);
 559                         kfree_skb(skb);
 560                         module_put(ss->owner);
 561                         status |= NFNL_BATCH_FAILURE;
 562                         goto replay_abort;
 563                 }
 564         }
 565         if (ss->cleanup)
 566                 ss->cleanup(net);
 567
 568         nfnl_err_deliver(&err_list, oskb);
 569         kfree_skb(skb);
 570         module_put(ss->owner);
 571 }
 572
 573 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
 574         [NFNL_BATCH_GENID]      = { .type = NLA_U32 },
 575 };
 576
 577 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
 578 {
 579         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
 580         struct nlattr *attr = (void *)nlh + min_len;
 581         struct nlattr *cda[NFNL_BATCH_MAX + 1];
 582         int attrlen = nlh->nlmsg_len - min_len;
 583         struct nfgenmsg *nfgenmsg;
 584         int msglen, err;
 585         u32 gen_id = 0;
 586         u16 res_id;
 587
 588         msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 589         if (msglen > skb->len)
 590                 msglen = skb->len;
 591
 592         if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
 593                 return;
 594
 595         err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
 596                                    nfnl_batch_policy, NULL);
 597         if (err < 0) {
 598                 netlink_ack(skb, nlh, err, NULL);
 599                 return;
 600         }
 601         if (cda[NFNL_BATCH_GENID])
 602                 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
 603
 604         nfgenmsg = nlmsg_data(nlh);
 605         skb_pull(skb, msglen);
 606         /* Work around old nft using host byte order */
 607         if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
 608                 res_id = NFNL_SUBSYS_NFTABLES;
 609         else
 610                 res_id = ntohs(nfgenmsg->res_id);
 611
 612         nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
 613 }
 614
 615 static void nfnetlink_rcv(struct sk_buff *skb)
 616 {
 617         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 618
 619         if (skb->len < NLMSG_HDRLEN ||
 620             nlh->nlmsg_len < NLMSG_HDRLEN ||
 621             skb->len < nlh->nlmsg_len)
 622                 return;
 623
 624         if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
 625                 netlink_ack(skb, nlh, -EPERM, NULL);
 626                 return;
 627         }
 628
 629         if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
 630                 nfnetlink_rcv_skb_batch(skb, nlh);
 631         else
 632                 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
 633 }
 634
 635 #ifdef CONFIG_MODULES
 636 static int nfnetlink_bind(struct net *net, int group)
 637 {
 638         const struct nfnetlink_subsystem *ss;
 639         int type;
 640
 641         if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
 642                 return 0;
 643
 644         type = nfnl_group2type[group];
 645
 646         rcu_read_lock();
 647         ss = nfnetlink_get_subsys(type << 8);
 648         rcu_read_unlock();
 649         if (!ss)
 650                 request_module_nowait("nfnetlink-subsys-%d", type);
 651         return 0;
 652 }
 653 #endif
 654
 655 static int __net_init nfnetlink_net_init(struct net *net)
 656 {
 657         struct nfnl_net *nfnlnet = nfnl_pernet(net);
 658         struct netlink_kernel_cfg cfg = {
 659                 .groups = NFNLGRP_MAX,
 660                 .input  = nfnetlink_rcv,
 661 #ifdef CONFIG_MODULES
 662                 .bind   = nfnetlink_bind,
 663 #endif
 664         };
 665
 666         nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
 667         if (!nfnlnet->nfnl)
 668                 return -ENOMEM;
 669         return 0;
 670 }
 671
 672 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
 673 {
 674         struct nfnl_net *nfnlnet;
 675         struct net *net;
 676
 677         list_for_each_entry(net, net_exit_list, exit_list) {
 678                 nfnlnet = nfnl_pernet(net);
 679
 680                 netlink_kernel_release(nfnlnet->nfnl);
 681         }
 682 }
 683
 684 static struct pernet_operations nfnetlink_net_ops = {
 685         .init           = nfnetlink_net_init,
 686         .exit_batch     = nfnetlink_net_exit_batch,
 687         .id             = &nfnetlink_pernet_id,
 688         .size           = sizeof(struct nfnl_net),
 689 };
 690
 691 static int __init nfnetlink_init(void)
 692 {
 693         int i;
 694
 695         for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
 696                 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
 697
 698         for (i=0; i<NFNL_SUBSYS_COUNT; i++)
 699                 __mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
 700
 701         return register_pernet_subsys(&nfnetlink_net_ops);
 702 }
 703
 704 static void __exit nfnetlink_exit(void)
 705 {
 706         unregister_pernet_subsys(&nfnetlink_net_ops);
 707 }
 708 module_init(nfnetlink_init);
 709 module_exit(nfnetlink_exit);