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.h> 33 #include <linux/netfilter/nfnetlink.h> 34 35 MODULE_LICENSE("GPL"); 36 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 37 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 38 MODULE_DESCRIPTION("Netfilter messages via netlink socket"); 39 40 #define nfnl_dereference_protected(id) \ 41 rcu_dereference_protected(table[(id)].subsys, \ 42 lockdep_nfnl_is_held((id))) 43 44 #define NFNL_MAX_ATTR_COUNT 32 45 46 static unsigned int nfnetlink_pernet_id __read_mostly; 47 48 #ifdef CONFIG_NF_CONNTRACK_EVENTS 49 static DEFINE_SPINLOCK(nfnl_grp_active_lock); 50 #endif 51 52 struct nfnl_net { 53 struct sock *nfnl; 54 }; 55 56 static struct { 57 struct mutex mutex; 58 const struct nfnetlink_subsystem __rcu *subsys; 59 } table[NFNL_SUBSYS_COUNT]; 60 61 static struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT]; 62 63 static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = { 64 [NFNL_SUBSYS_NONE] = "nfnl_subsys_none", 65 [NFNL_SUBSYS_CTNETLINK] = "nfnl_subsys_ctnetlink", 66 [NFNL_SUBSYS_CTNETLINK_EXP] = "nfnl_subsys_ctnetlink_exp", 67 [NFNL_SUBSYS_QUEUE] = "nfnl_subsys_queue", 68 [NFNL_SUBSYS_ULOG] = "nfnl_subsys_ulog", 69 [NFNL_SUBSYS_OSF] = "nfnl_subsys_osf", 70 [NFNL_SUBSYS_IPSET] = "nfnl_subsys_ipset", 71 [NFNL_SUBSYS_ACCT] = "nfnl_subsys_acct", 72 [NFNL_SUBSYS_CTNETLINK_TIMEOUT] = "nfnl_subsys_cttimeout", 73 [NFNL_SUBSYS_CTHELPER] = "nfnl_subsys_cthelper", 74 [NFNL_SUBSYS_NFTABLES] = "nfnl_subsys_nftables", 75 [NFNL_SUBSYS_NFT_COMPAT] = "nfnl_subsys_nftcompat", 76 [NFNL_SUBSYS_HOOK] = "nfnl_subsys_hook", 77 }; 78 79 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 80 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 81 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 82 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 83 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 84 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 85 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 86 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES, 87 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT, 88 [NFNLGRP_NFTRACE] = NFNL_SUBSYS_NFTABLES, 89 }; 90 91 static struct nfnl_net *nfnl_pernet(struct net *net) 92 { 93 return net_generic(net, nfnetlink_pernet_id); 94 } 95 96 void nfnl_lock(__u8 subsys_id) 97 { 98 mutex_lock(&table[subsys_id].mutex); 99 } 100 EXPORT_SYMBOL_GPL(nfnl_lock); 101 102 void nfnl_unlock(__u8 subsys_id) 103 { 104 mutex_unlock(&table[subsys_id].mutex); 105 } 106 EXPORT_SYMBOL_GPL(nfnl_unlock); 107 108 #ifdef CONFIG_PROVE_LOCKING 109 bool lockdep_nfnl_is_held(u8 subsys_id) 110 { 111 return lockdep_is_held(&table[subsys_id].mutex); 112 } 113 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); 114 #endif 115 116 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 117 { 118 u8 cb_id; 119 120 /* Sanity-check attr_count size to avoid stack buffer overflow. */ 121 for (cb_id = 0; cb_id < n->cb_count; cb_id++) 122 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT)) 123 return -EINVAL; 124 125 nfnl_lock(n->subsys_id); 126 if (table[n->subsys_id].subsys) { 127 nfnl_unlock(n->subsys_id); 128 return -EBUSY; 129 } 130 rcu_assign_pointer(table[n->subsys_id].subsys, n); 131 nfnl_unlock(n->subsys_id); 132 133 return 0; 134 } 135 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 136 137 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 138 { 139 nfnl_lock(n->subsys_id); 140 table[n->subsys_id].subsys = NULL; 141 nfnl_unlock(n->subsys_id); 142 synchronize_rcu(); 143 return 0; 144 } 145 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 146 147 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type) 148 { 149 u8 subsys_id = NFNL_SUBSYS_ID(type); 150 151 if (subsys_id >= NFNL_SUBSYS_COUNT) 152 return NULL; 153 154 return rcu_dereference(table[subsys_id].subsys); 155 } 156 157 static inline const struct nfnl_callback * 158 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss) 159 { 160 u8 cb_id = NFNL_MSG_TYPE(type); 161 162 if (cb_id >= ss->cb_count) 163 return NULL; 164 165 return &ss->cb[cb_id]; 166 } 167 168 int nfnetlink_has_listeners(struct net *net, unsigned int group) 169 { 170 struct nfnl_net *nfnlnet = nfnl_pernet(net); 171 172 return netlink_has_listeners(nfnlnet->nfnl, group); 173 } 174 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 175 176 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, 177 unsigned int group, int echo, gfp_t flags) 178 { 179 struct nfnl_net *nfnlnet = nfnl_pernet(net); 180 181 return nlmsg_notify(nfnlnet->nfnl, skb, portid, group, echo, flags); 182 } 183 EXPORT_SYMBOL_GPL(nfnetlink_send); 184 185 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) 186 { 187 struct nfnl_net *nfnlnet = nfnl_pernet(net); 188 189 return netlink_set_err(nfnlnet->nfnl, portid, group, error); 190 } 191 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 192 193 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid) 194 { 195 struct nfnl_net *nfnlnet = nfnl_pernet(net); 196 int err; 197 198 err = nlmsg_unicast(nfnlnet->nfnl, skb, portid); 199 if (err == -EAGAIN) 200 err = -ENOBUFS; 201 202 return err; 203 } 204 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 205 206 void nfnetlink_broadcast(struct net *net, struct sk_buff *skb, __u32 portid, 207 __u32 group, gfp_t allocation) 208 { 209 struct nfnl_net *nfnlnet = nfnl_pernet(net); 210 211 netlink_broadcast(nfnlnet->nfnl, skb, portid, group, allocation); 212 } 213 EXPORT_SYMBOL_GPL(nfnetlink_broadcast); 214 215 /* Process one complete nfnetlink message. */ 216 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 217 struct netlink_ext_ack *extack) 218 { 219 struct net *net = sock_net(skb->sk); 220 const struct nfnl_callback *nc; 221 const struct nfnetlink_subsystem *ss; 222 int type, err; 223 224 /* All the messages must at least contain nfgenmsg */ 225 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) 226 return 0; 227 228 type = nlh->nlmsg_type; 229 replay: 230 rcu_read_lock(); 231 232 ss = nfnetlink_get_subsys(type); 233 if (!ss) { 234 #ifdef CONFIG_MODULES 235 rcu_read_unlock(); 236 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 237 rcu_read_lock(); 238 ss = nfnetlink_get_subsys(type); 239 if (!ss) 240 #endif 241 { 242 rcu_read_unlock(); 243 return -EINVAL; 244 } 245 } 246 247 nc = nfnetlink_find_client(type, ss); 248 if (!nc) { 249 rcu_read_unlock(); 250 return -EINVAL; 251 } 252 253 { 254 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 255 struct nfnl_net *nfnlnet = nfnl_pernet(net); 256 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 257 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; 258 struct nlattr *attr = (void *)nlh + min_len; 259 int attrlen = nlh->nlmsg_len - min_len; 260 __u8 subsys_id = NFNL_SUBSYS_ID(type); 261 struct nfnl_info info = { 262 .net = net, 263 .sk = nfnlnet->nfnl, 264 .nlh = nlh, 265 .nfmsg = nlmsg_data(nlh), 266 .extack = extack, 267 }; 268 269 /* Sanity-check NFNL_MAX_ATTR_COUNT */ 270 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { 271 rcu_read_unlock(); 272 return -ENOMEM; 273 } 274 275 err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count, 276 attr, attrlen, 277 ss->cb[cb_id].policy, extack); 278 if (err < 0) { 279 rcu_read_unlock(); 280 return err; 281 } 282 283 if (!nc->call) { 284 rcu_read_unlock(); 285 return -EINVAL; 286 } 287 288 switch (nc->type) { 289 case NFNL_CB_RCU: 290 err = nc->call(skb, &info, (const struct nlattr **)cda); 291 rcu_read_unlock(); 292 break; 293 case NFNL_CB_MUTEX: 294 rcu_read_unlock(); 295 nfnl_lock(subsys_id); 296 if (nfnl_dereference_protected(subsys_id) != ss || 297 nfnetlink_find_client(type, ss) != nc) { 298 nfnl_unlock(subsys_id); 299 err = -EAGAIN; 300 break; 301 } 302 err = nc->call(skb, &info, (const struct nlattr **)cda); 303 nfnl_unlock(subsys_id); 304 break; 305 default: 306 rcu_read_unlock(); 307 err = -EINVAL; 308 break; 309 } 310 if (err == -EAGAIN) 311 goto replay; 312 return err; 313 } 314 } 315 316 struct nfnl_err { 317 struct list_head head; 318 struct nlmsghdr *nlh; 319 int err; 320 struct netlink_ext_ack extack; 321 }; 322 323 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err, 324 const struct netlink_ext_ack *extack) 325 { 326 struct nfnl_err *nfnl_err; 327 328 nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL); 329 if (nfnl_err == NULL) 330 return -ENOMEM; 331 332 nfnl_err->nlh = nlh; 333 nfnl_err->err = err; 334 nfnl_err->extack = *extack; 335 list_add_tail(&nfnl_err->head, list); 336 337 return 0; 338 } 339 340 static void nfnl_err_del(struct nfnl_err *nfnl_err) 341 { 342 list_del(&nfnl_err->head); 343 kfree(nfnl_err); 344 } 345 346 static void nfnl_err_reset(struct list_head *err_list) 347 { 348 struct nfnl_err *nfnl_err, *next; 349 350 list_for_each_entry_safe(nfnl_err, next, err_list, head) 351 nfnl_err_del(nfnl_err); 352 } 353 354 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb) 355 { 356 struct nfnl_err *nfnl_err, *next; 357 358 list_for_each_entry_safe(nfnl_err, next, err_list, head) { 359 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err, 360 &nfnl_err->extack); 361 nfnl_err_del(nfnl_err); 362 } 363 } 364 365 enum { 366 NFNL_BATCH_FAILURE = (1 << 0), 367 NFNL_BATCH_DONE = (1 << 1), 368 NFNL_BATCH_REPLAY = (1 << 2), 369 }; 370 371 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, 372 u16 subsys_id, u32 genid) 373 { 374 struct sk_buff *oskb = skb; 375 struct net *net = sock_net(skb->sk); 376 const struct nfnetlink_subsystem *ss; 377 const struct nfnl_callback *nc; 378 struct netlink_ext_ack extack; 379 LIST_HEAD(err_list); 380 u32 status; 381 int err; 382 383 if (subsys_id >= NFNL_SUBSYS_COUNT) 384 return netlink_ack(skb, nlh, -EINVAL, NULL); 385 replay: 386 status = 0; 387 replay_abort: 388 skb = netlink_skb_clone(oskb, GFP_KERNEL); 389 if (!skb) 390 return netlink_ack(oskb, nlh, -ENOMEM, NULL); 391 392 nfnl_lock(subsys_id); 393 ss = nfnl_dereference_protected(subsys_id); 394 if (!ss) { 395 #ifdef CONFIG_MODULES 396 nfnl_unlock(subsys_id); 397 request_module("nfnetlink-subsys-%d", subsys_id); 398 nfnl_lock(subsys_id); 399 ss = nfnl_dereference_protected(subsys_id); 400 if (!ss) 401 #endif 402 { 403 nfnl_unlock(subsys_id); 404 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); 405 return kfree_skb(skb); 406 } 407 } 408 409 if (!ss->valid_genid || !ss->commit || !ss->abort) { 410 nfnl_unlock(subsys_id); 411 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); 412 return kfree_skb(skb); 413 } 414 415 if (!try_module_get(ss->owner)) { 416 nfnl_unlock(subsys_id); 417 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); 418 return kfree_skb(skb); 419 } 420 421 if (!ss->valid_genid(net, genid)) { 422 module_put(ss->owner); 423 nfnl_unlock(subsys_id); 424 netlink_ack(oskb, nlh, -ERESTART, NULL); 425 return kfree_skb(skb); 426 } 427 428 nfnl_unlock(subsys_id); 429 430 while (skb->len >= nlmsg_total_size(0)) { 431 int msglen, type; 432 433 if (fatal_signal_pending(current)) { 434 nfnl_err_reset(&err_list); 435 err = -EINTR; 436 status = NFNL_BATCH_FAILURE; 437 goto done; 438 } 439 440 memset(&extack, 0, sizeof(extack)); 441 nlh = nlmsg_hdr(skb); 442 err = 0; 443 444 if (nlh->nlmsg_len < NLMSG_HDRLEN || 445 skb->len < nlh->nlmsg_len || 446 nlmsg_len(nlh) < sizeof(struct nfgenmsg)) { 447 nfnl_err_reset(&err_list); 448 status |= NFNL_BATCH_FAILURE; 449 goto done; 450 } 451 452 /* Only requests are handled by the kernel */ 453 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { 454 err = -EINVAL; 455 goto ack; 456 } 457 458 type = nlh->nlmsg_type; 459 if (type == NFNL_MSG_BATCH_BEGIN) { 460 /* Malformed: Batch begin twice */ 461 nfnl_err_reset(&err_list); 462 status |= NFNL_BATCH_FAILURE; 463 goto done; 464 } else if (type == NFNL_MSG_BATCH_END) { 465 status |= NFNL_BATCH_DONE; 466 goto done; 467 } else if (type < NLMSG_MIN_TYPE) { 468 err = -EINVAL; 469 goto ack; 470 } 471 472 /* We only accept a batch with messages for the same 473 * subsystem. 474 */ 475 if (NFNL_SUBSYS_ID(type) != subsys_id) { 476 err = -EINVAL; 477 goto ack; 478 } 479 480 nc = nfnetlink_find_client(type, ss); 481 if (!nc) { 482 err = -EINVAL; 483 goto ack; 484 } 485 486 if (nc->type != NFNL_CB_BATCH) { 487 err = -EINVAL; 488 goto ack; 489 } 490 491 { 492 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 493 struct nfnl_net *nfnlnet = nfnl_pernet(net); 494 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; 495 struct nlattr *attr = (void *)nlh + min_len; 496 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 497 int attrlen = nlh->nlmsg_len - min_len; 498 struct nfnl_info info = { 499 .net = net, 500 .sk = nfnlnet->nfnl, 501 .nlh = nlh, 502 .nfmsg = nlmsg_data(nlh), 503 .extack = &extack, 504 }; 505 506 /* Sanity-check NFTA_MAX_ATTR */ 507 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { 508 err = -ENOMEM; 509 goto ack; 510 } 511 512 err = nla_parse_deprecated(cda, 513 ss->cb[cb_id].attr_count, 514 attr, attrlen, 515 ss->cb[cb_id].policy, NULL); 516 if (err < 0) 517 goto ack; 518 519 err = nc->call(skb, &info, (const struct nlattr **)cda); 520 521 /* The lock was released to autoload some module, we 522 * have to abort and start from scratch using the 523 * original skb. 524 */ 525 if (err == -EAGAIN) { 526 status |= NFNL_BATCH_REPLAY; 527 goto done; 528 } 529 } 530 ack: 531 if (nlh->nlmsg_flags & NLM_F_ACK || err) { 532 /* Errors are delivered once the full batch has been 533 * processed, this avoids that the same error is 534 * reported several times when replaying the batch. 535 */ 536 if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) { 537 /* We failed to enqueue an error, reset the 538 * list of errors and send OOM to userspace 539 * pointing to the batch header. 540 */ 541 nfnl_err_reset(&err_list); 542 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM, 543 NULL); 544 status |= NFNL_BATCH_FAILURE; 545 goto done; 546 } 547 /* We don't stop processing the batch on errors, thus, 548 * userspace gets all the errors that the batch 549 * triggers. 550 */ 551 if (err) 552 status |= NFNL_BATCH_FAILURE; 553 } 554 555 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 556 if (msglen > skb->len) 557 msglen = skb->len; 558 skb_pull(skb, msglen); 559 } 560 done: 561 if (status & NFNL_BATCH_REPLAY) { 562 ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD); 563 nfnl_err_reset(&err_list); 564 kfree_skb(skb); 565 module_put(ss->owner); 566 goto replay; 567 } else if (status == NFNL_BATCH_DONE) { 568 err = ss->commit(net, oskb); 569 if (err == -EAGAIN) { 570 status |= NFNL_BATCH_REPLAY; 571 goto done; 572 } else if (err) { 573 ss->abort(net, oskb, NFNL_ABORT_NONE); 574 netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL); 575 } 576 } else { 577 enum nfnl_abort_action abort_action; 578 579 if (status & NFNL_BATCH_FAILURE) 580 abort_action = NFNL_ABORT_NONE; 581 else 582 abort_action = NFNL_ABORT_VALIDATE; 583 584 err = ss->abort(net, oskb, abort_action); 585 if (err == -EAGAIN) { 586 nfnl_err_reset(&err_list); 587 kfree_skb(skb); 588 module_put(ss->owner); 589 status |= NFNL_BATCH_FAILURE; 590 goto replay_abort; 591 } 592 } 593 594 nfnl_err_deliver(&err_list, oskb); 595 kfree_skb(skb); 596 module_put(ss->owner); 597 } 598 599 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = { 600 [NFNL_BATCH_GENID] = { .type = NLA_U32 }, 601 }; 602 603 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh) 604 { 605 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 606 struct nlattr *attr = (void *)nlh + min_len; 607 struct nlattr *cda[NFNL_BATCH_MAX + 1]; 608 int attrlen = nlh->nlmsg_len - min_len; 609 struct nfgenmsg *nfgenmsg; 610 int msglen, err; 611 u32 gen_id = 0; 612 u16 res_id; 613 614 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 615 if (msglen > skb->len) 616 msglen = skb->len; 617 618 if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) 619 return; 620 621 err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen, 622 nfnl_batch_policy, NULL); 623 if (err < 0) { 624 netlink_ack(skb, nlh, err, NULL); 625 return; 626 } 627 if (cda[NFNL_BATCH_GENID]) 628 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID])); 629 630 nfgenmsg = nlmsg_data(nlh); 631 skb_pull(skb, msglen); 632 /* Work around old nft using host byte order */ 633 if (nfgenmsg->res_id == (__force __be16)NFNL_SUBSYS_NFTABLES) 634 res_id = NFNL_SUBSYS_NFTABLES; 635 else 636 res_id = ntohs(nfgenmsg->res_id); 637 638 nfnetlink_rcv_batch(skb, nlh, res_id, gen_id); 639 } 640 641 static void nfnetlink_rcv(struct sk_buff *skb) 642 { 643 struct nlmsghdr *nlh = nlmsg_hdr(skb); 644 645 if (skb->len < NLMSG_HDRLEN || 646 nlh->nlmsg_len < NLMSG_HDRLEN || 647 skb->len < nlh->nlmsg_len) 648 return; 649 650 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { 651 netlink_ack(skb, nlh, -EPERM, NULL); 652 return; 653 } 654 655 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) 656 nfnetlink_rcv_skb_batch(skb, nlh); 657 else 658 netlink_rcv_skb(skb, nfnetlink_rcv_msg); 659 } 660 661 static void nfnetlink_bind_event(struct net *net, unsigned int group) 662 { 663 #ifdef CONFIG_NF_CONNTRACK_EVENTS 664 int type, group_bit; 665 u8 v; 666 667 /* All NFNLGRP_CONNTRACK_* group bits fit into u8. 668 * The other groups are not relevant and can be ignored. 669 */ 670 if (group >= 8) 671 return; 672 673 type = nfnl_group2type[group]; 674 675 switch (type) { 676 case NFNL_SUBSYS_CTNETLINK: 677 break; 678 case NFNL_SUBSYS_CTNETLINK_EXP: 679 break; 680 default: 681 return; 682 } 683 684 group_bit = (1 << group); 685 686 spin_lock(&nfnl_grp_active_lock); 687 v = READ_ONCE(nf_ctnetlink_has_listener); 688 if ((v & group_bit) == 0) { 689 v |= group_bit; 690 691 /* read concurrently without nfnl_grp_active_lock held. */ 692 WRITE_ONCE(nf_ctnetlink_has_listener, v); 693 } 694 695 spin_unlock(&nfnl_grp_active_lock); 696 #endif 697 } 698 699 static int nfnetlink_bind(struct net *net, int group) 700 { 701 const struct nfnetlink_subsystem *ss; 702 int type; 703 704 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) 705 return 0; 706 707 type = nfnl_group2type[group]; 708 709 rcu_read_lock(); 710 ss = nfnetlink_get_subsys(type << 8); 711 rcu_read_unlock(); 712 if (!ss) 713 request_module_nowait("nfnetlink-subsys-%d", type); 714 715 nfnetlink_bind_event(net, group); 716 return 0; 717 } 718 719 static void nfnetlink_unbind(struct net *net, int group) 720 { 721 #ifdef CONFIG_NF_CONNTRACK_EVENTS 722 int type, group_bit; 723 724 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) 725 return; 726 727 type = nfnl_group2type[group]; 728 729 switch (type) { 730 case NFNL_SUBSYS_CTNETLINK: 731 break; 732 case NFNL_SUBSYS_CTNETLINK_EXP: 733 break; 734 default: 735 return; 736 } 737 738 /* ctnetlink_has_listener is u8 */ 739 if (group >= 8) 740 return; 741 742 group_bit = (1 << group); 743 744 spin_lock(&nfnl_grp_active_lock); 745 if (!nfnetlink_has_listeners(net, group)) { 746 u8 v = READ_ONCE(nf_ctnetlink_has_listener); 747 748 v &= ~group_bit; 749 750 /* read concurrently without nfnl_grp_active_lock held. */ 751 WRITE_ONCE(nf_ctnetlink_has_listener, v); 752 } 753 spin_unlock(&nfnl_grp_active_lock); 754 #endif 755 } 756 757 static int __net_init nfnetlink_net_init(struct net *net) 758 { 759 struct nfnl_net *nfnlnet = nfnl_pernet(net); 760 struct netlink_kernel_cfg cfg = { 761 .groups = NFNLGRP_MAX, 762 .input = nfnetlink_rcv, 763 .bind = nfnetlink_bind, 764 .unbind = nfnetlink_unbind, 765 }; 766 767 nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 768 if (!nfnlnet->nfnl) 769 return -ENOMEM; 770 return 0; 771 } 772 773 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 774 { 775 struct nfnl_net *nfnlnet; 776 struct net *net; 777 778 list_for_each_entry(net, net_exit_list, exit_list) { 779 nfnlnet = nfnl_pernet(net); 780 781 netlink_kernel_release(nfnlnet->nfnl); 782 } 783 } 784 785 static struct pernet_operations nfnetlink_net_ops = { 786 .init = nfnetlink_net_init, 787 .exit_batch = nfnetlink_net_exit_batch, 788 .id = &nfnetlink_pernet_id, 789 .size = sizeof(struct nfnl_net), 790 }; 791 792 static int __init nfnetlink_init(void) 793 { 794 int i; 795 796 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++) 797 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE); 798 799 for (i=0; i<NFNL_SUBSYS_COUNT; i++) 800 __mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]); 801 802 return register_pernet_subsys(&nfnetlink_net_ops); 803 } 804 805 static void __exit nfnetlink_exit(void) 806 { 807 unregister_pernet_subsys(&nfnetlink_net_ops); 808 } 809 module_init(nfnetlink_init); 810 module_exit(nfnetlink_exit); 811