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) 2005,2007 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 <asm/uaccess.h> 26 #include <net/sock.h> 27 #include <linux/init.h> 28 29 #include <net/netlink.h> 30 #include <linux/netfilter/nfnetlink.h> 31 32 MODULE_LICENSE("GPL"); 33 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 34 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 35 36 static char __initdata nfversion[] = "0.30"; 37 38 static struct { 39 struct mutex mutex; 40 const struct nfnetlink_subsystem __rcu *subsys; 41 } table[NFNL_SUBSYS_COUNT]; 42 43 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 44 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 45 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 46 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 47 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 48 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 49 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 50 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES, 51 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT, 52 }; 53 54 void nfnl_lock(__u8 subsys_id) 55 { 56 mutex_lock(&table[subsys_id].mutex); 57 } 58 EXPORT_SYMBOL_GPL(nfnl_lock); 59 60 void nfnl_unlock(__u8 subsys_id) 61 { 62 mutex_unlock(&table[subsys_id].mutex); 63 } 64 EXPORT_SYMBOL_GPL(nfnl_unlock); 65 66 #ifdef CONFIG_PROVE_LOCKING 67 bool lockdep_nfnl_is_held(u8 subsys_id) 68 { 69 return lockdep_is_held(&table[subsys_id].mutex); 70 } 71 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); 72 #endif 73 74 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 75 { 76 nfnl_lock(n->subsys_id); 77 if (table[n->subsys_id].subsys) { 78 nfnl_unlock(n->subsys_id); 79 return -EBUSY; 80 } 81 rcu_assign_pointer(table[n->subsys_id].subsys, n); 82 nfnl_unlock(n->subsys_id); 83 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 87 88 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 89 { 90 nfnl_lock(n->subsys_id); 91 table[n->subsys_id].subsys = NULL; 92 nfnl_unlock(n->subsys_id); 93 synchronize_rcu(); 94 return 0; 95 } 96 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 97 98 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 99 { 100 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 101 102 if (subsys_id >= NFNL_SUBSYS_COUNT) 103 return NULL; 104 105 return rcu_dereference(table[subsys_id].subsys); 106 } 107 108 static inline const struct nfnl_callback * 109 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 110 { 111 u_int8_t cb_id = NFNL_MSG_TYPE(type); 112 113 if (cb_id >= ss->cb_count) 114 return NULL; 115 116 return &ss->cb[cb_id]; 117 } 118 119 int nfnetlink_has_listeners(struct net *net, unsigned int group) 120 { 121 return netlink_has_listeners(net->nfnl, group); 122 } 123 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 124 125 struct sk_buff *nfnetlink_alloc_skb(struct net *net, unsigned int size, 126 u32 dst_portid, gfp_t gfp_mask) 127 { 128 return netlink_alloc_skb(net->nfnl, size, dst_portid, gfp_mask); 129 } 130 EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb); 131 132 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, 133 unsigned int group, int echo, gfp_t flags) 134 { 135 return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); 136 } 137 EXPORT_SYMBOL_GPL(nfnetlink_send); 138 139 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) 140 { 141 return netlink_set_err(net->nfnl, portid, group, error); 142 } 143 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 144 145 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, 146 int flags) 147 { 148 return netlink_unicast(net->nfnl, skb, portid, flags); 149 } 150 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 151 152 /* Process one complete nfnetlink message. */ 153 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 154 { 155 struct net *net = sock_net(skb->sk); 156 const struct nfnl_callback *nc; 157 const struct nfnetlink_subsystem *ss; 158 int type, err; 159 160 /* All the messages must at least contain nfgenmsg */ 161 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) 162 return 0; 163 164 type = nlh->nlmsg_type; 165 replay: 166 rcu_read_lock(); 167 ss = nfnetlink_get_subsys(type); 168 if (!ss) { 169 #ifdef CONFIG_MODULES 170 rcu_read_unlock(); 171 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 172 rcu_read_lock(); 173 ss = nfnetlink_get_subsys(type); 174 if (!ss) 175 #endif 176 { 177 rcu_read_unlock(); 178 return -EINVAL; 179 } 180 } 181 182 nc = nfnetlink_find_client(type, ss); 183 if (!nc) { 184 rcu_read_unlock(); 185 return -EINVAL; 186 } 187 188 { 189 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 190 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 191 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 192 struct nlattr *attr = (void *)nlh + min_len; 193 int attrlen = nlh->nlmsg_len - min_len; 194 __u8 subsys_id = NFNL_SUBSYS_ID(type); 195 196 err = nla_parse(cda, ss->cb[cb_id].attr_count, 197 attr, attrlen, ss->cb[cb_id].policy); 198 if (err < 0) { 199 rcu_read_unlock(); 200 return err; 201 } 202 203 if (nc->call_rcu) { 204 err = nc->call_rcu(net->nfnl, skb, nlh, 205 (const struct nlattr **)cda); 206 rcu_read_unlock(); 207 } else { 208 rcu_read_unlock(); 209 nfnl_lock(subsys_id); 210 if (rcu_dereference_protected(table[subsys_id].subsys, 211 lockdep_is_held(&table[subsys_id].mutex)) != ss || 212 nfnetlink_find_client(type, ss) != nc) 213 err = -EAGAIN; 214 else if (nc->call) 215 err = nc->call(net->nfnl, skb, nlh, 216 (const struct nlattr **)cda); 217 else 218 err = -EINVAL; 219 nfnl_unlock(subsys_id); 220 } 221 if (err == -EAGAIN) 222 goto replay; 223 return err; 224 } 225 } 226 227 struct nfnl_err { 228 struct list_head head; 229 struct nlmsghdr *nlh; 230 int err; 231 }; 232 233 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err) 234 { 235 struct nfnl_err *nfnl_err; 236 237 nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL); 238 if (nfnl_err == NULL) 239 return -ENOMEM; 240 241 nfnl_err->nlh = nlh; 242 nfnl_err->err = err; 243 list_add_tail(&nfnl_err->head, list); 244 245 return 0; 246 } 247 248 static void nfnl_err_del(struct nfnl_err *nfnl_err) 249 { 250 list_del(&nfnl_err->head); 251 kfree(nfnl_err); 252 } 253 254 static void nfnl_err_reset(struct list_head *err_list) 255 { 256 struct nfnl_err *nfnl_err, *next; 257 258 list_for_each_entry_safe(nfnl_err, next, err_list, head) 259 nfnl_err_del(nfnl_err); 260 } 261 262 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb) 263 { 264 struct nfnl_err *nfnl_err, *next; 265 266 list_for_each_entry_safe(nfnl_err, next, err_list, head) { 267 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err); 268 nfnl_err_del(nfnl_err); 269 } 270 } 271 272 enum { 273 NFNL_BATCH_FAILURE = (1 << 0), 274 NFNL_BATCH_DONE = (1 << 1), 275 NFNL_BATCH_REPLAY = (1 << 2), 276 }; 277 278 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, 279 u_int16_t subsys_id) 280 { 281 struct sk_buff *oskb = skb; 282 struct net *net = sock_net(skb->sk); 283 const struct nfnetlink_subsystem *ss; 284 const struct nfnl_callback *nc; 285 static LIST_HEAD(err_list); 286 u32 status; 287 int err; 288 289 if (subsys_id >= NFNL_SUBSYS_COUNT) 290 return netlink_ack(skb, nlh, -EINVAL); 291 replay: 292 status = 0; 293 294 skb = netlink_skb_clone(oskb, GFP_KERNEL); 295 if (!skb) 296 return netlink_ack(oskb, nlh, -ENOMEM); 297 298 nfnl_lock(subsys_id); 299 ss = rcu_dereference_protected(table[subsys_id].subsys, 300 lockdep_is_held(&table[subsys_id].mutex)); 301 if (!ss) { 302 #ifdef CONFIG_MODULES 303 nfnl_unlock(subsys_id); 304 request_module("nfnetlink-subsys-%d", subsys_id); 305 nfnl_lock(subsys_id); 306 ss = rcu_dereference_protected(table[subsys_id].subsys, 307 lockdep_is_held(&table[subsys_id].mutex)); 308 if (!ss) 309 #endif 310 { 311 nfnl_unlock(subsys_id); 312 netlink_ack(skb, nlh, -EOPNOTSUPP); 313 return kfree_skb(skb); 314 } 315 } 316 317 if (!ss->commit || !ss->abort) { 318 nfnl_unlock(subsys_id); 319 netlink_ack(skb, nlh, -EOPNOTSUPP); 320 return kfree_skb(skb); 321 } 322 323 while (skb->len >= nlmsg_total_size(0)) { 324 int msglen, type; 325 326 nlh = nlmsg_hdr(skb); 327 err = 0; 328 329 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg) || 330 skb->len < nlh->nlmsg_len) { 331 err = -EINVAL; 332 goto ack; 333 } 334 335 /* Only requests are handled by the kernel */ 336 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { 337 err = -EINVAL; 338 goto ack; 339 } 340 341 type = nlh->nlmsg_type; 342 if (type == NFNL_MSG_BATCH_BEGIN) { 343 /* Malformed: Batch begin twice */ 344 nfnl_err_reset(&err_list); 345 status |= NFNL_BATCH_FAILURE; 346 goto done; 347 } else if (type == NFNL_MSG_BATCH_END) { 348 status |= NFNL_BATCH_DONE; 349 goto done; 350 } else if (type < NLMSG_MIN_TYPE) { 351 err = -EINVAL; 352 goto ack; 353 } 354 355 /* We only accept a batch with messages for the same 356 * subsystem. 357 */ 358 if (NFNL_SUBSYS_ID(type) != subsys_id) { 359 err = -EINVAL; 360 goto ack; 361 } 362 363 nc = nfnetlink_find_client(type, ss); 364 if (!nc) { 365 err = -EINVAL; 366 goto ack; 367 } 368 369 { 370 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 371 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 372 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 373 struct nlattr *attr = (void *)nlh + min_len; 374 int attrlen = nlh->nlmsg_len - min_len; 375 376 err = nla_parse(cda, ss->cb[cb_id].attr_count, 377 attr, attrlen, ss->cb[cb_id].policy); 378 if (err < 0) 379 goto ack; 380 381 if (nc->call_batch) { 382 err = nc->call_batch(net, net->nfnl, skb, nlh, 383 (const struct nlattr **)cda); 384 } 385 386 /* The lock was released to autoload some module, we 387 * have to abort and start from scratch using the 388 * original skb. 389 */ 390 if (err == -EAGAIN) { 391 status |= NFNL_BATCH_REPLAY; 392 goto next; 393 } 394 } 395 ack: 396 if (nlh->nlmsg_flags & NLM_F_ACK || err) { 397 /* Errors are delivered once the full batch has been 398 * processed, this avoids that the same error is 399 * reported several times when replaying the batch. 400 */ 401 if (nfnl_err_add(&err_list, nlh, err) < 0) { 402 /* We failed to enqueue an error, reset the 403 * list of errors and send OOM to userspace 404 * pointing to the batch header. 405 */ 406 nfnl_err_reset(&err_list); 407 netlink_ack(skb, nlmsg_hdr(oskb), -ENOMEM); 408 status |= NFNL_BATCH_FAILURE; 409 goto done; 410 } 411 /* We don't stop processing the batch on errors, thus, 412 * userspace gets all the errors that the batch 413 * triggers. 414 */ 415 if (err) 416 status |= NFNL_BATCH_FAILURE; 417 } 418 next: 419 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 420 if (msglen > skb->len) 421 msglen = skb->len; 422 skb_pull(skb, msglen); 423 } 424 done: 425 if (status & NFNL_BATCH_REPLAY) { 426 ss->abort(oskb); 427 nfnl_err_reset(&err_list); 428 nfnl_unlock(subsys_id); 429 kfree_skb(skb); 430 goto replay; 431 } else if (status == NFNL_BATCH_DONE) { 432 ss->commit(oskb); 433 } else { 434 ss->abort(oskb); 435 } 436 437 nfnl_err_deliver(&err_list, oskb); 438 nfnl_unlock(subsys_id); 439 kfree_skb(skb); 440 } 441 442 static void nfnetlink_rcv(struct sk_buff *skb) 443 { 444 struct nlmsghdr *nlh = nlmsg_hdr(skb); 445 u_int16_t res_id; 446 int msglen; 447 448 if (nlh->nlmsg_len < NLMSG_HDRLEN || 449 skb->len < nlh->nlmsg_len) 450 return; 451 452 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { 453 netlink_ack(skb, nlh, -EPERM); 454 return; 455 } 456 457 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) { 458 struct nfgenmsg *nfgenmsg; 459 460 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 461 if (msglen > skb->len) 462 msglen = skb->len; 463 464 if (nlh->nlmsg_len < NLMSG_HDRLEN || 465 skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) 466 return; 467 468 nfgenmsg = nlmsg_data(nlh); 469 skb_pull(skb, msglen); 470 /* Work around old nft using host byte order */ 471 if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES) 472 res_id = NFNL_SUBSYS_NFTABLES; 473 else 474 res_id = ntohs(nfgenmsg->res_id); 475 nfnetlink_rcv_batch(skb, nlh, res_id); 476 } else { 477 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 478 } 479 } 480 481 #ifdef CONFIG_MODULES 482 static int nfnetlink_bind(struct net *net, int group) 483 { 484 const struct nfnetlink_subsystem *ss; 485 int type; 486 487 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) 488 return 0; 489 490 type = nfnl_group2type[group]; 491 492 rcu_read_lock(); 493 ss = nfnetlink_get_subsys(type << 8); 494 rcu_read_unlock(); 495 if (!ss) 496 request_module("nfnetlink-subsys-%d", type); 497 return 0; 498 } 499 #endif 500 501 static int __net_init nfnetlink_net_init(struct net *net) 502 { 503 struct sock *nfnl; 504 struct netlink_kernel_cfg cfg = { 505 .groups = NFNLGRP_MAX, 506 .input = nfnetlink_rcv, 507 #ifdef CONFIG_MODULES 508 .bind = nfnetlink_bind, 509 #endif 510 }; 511 512 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 513 if (!nfnl) 514 return -ENOMEM; 515 net->nfnl_stash = nfnl; 516 rcu_assign_pointer(net->nfnl, nfnl); 517 return 0; 518 } 519 520 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 521 { 522 struct net *net; 523 524 list_for_each_entry(net, net_exit_list, exit_list) 525 RCU_INIT_POINTER(net->nfnl, NULL); 526 synchronize_net(); 527 list_for_each_entry(net, net_exit_list, exit_list) 528 netlink_kernel_release(net->nfnl_stash); 529 } 530 531 static struct pernet_operations nfnetlink_net_ops = { 532 .init = nfnetlink_net_init, 533 .exit_batch = nfnetlink_net_exit_batch, 534 }; 535 536 static int __init nfnetlink_init(void) 537 { 538 int i; 539 540 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++) 541 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE); 542 543 for (i=0; i<NFNL_SUBSYS_COUNT; i++) 544 mutex_init(&table[i].mutex); 545 546 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 547 return register_pernet_subsys(&nfnetlink_net_ops); 548 } 549 550 static void __exit nfnetlink_exit(void) 551 { 552 pr_info("Removing netfilter NETLINK layer.\n"); 553 unregister_pernet_subsys(&nfnetlink_net_ops); 554 } 555 module_init(nfnetlink_init); 556 module_exit(nfnetlink_exit); 557