1 /* 2 * net/core/fib_rules.c Generic Routing Rules 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation, version 2. 7 * 8 * Authors: Thomas Graf <tgraf@suug.ch> 9 */ 10 11 #include <linux/types.h> 12 #include <linux/kernel.h> 13 #include <linux/list.h> 14 #include <net/net_namespace.h> 15 #include <net/sock.h> 16 #include <net/fib_rules.h> 17 18 int fib_default_rule_add(struct fib_rules_ops *ops, 19 u32 pref, u32 table, u32 flags) 20 { 21 struct fib_rule *r; 22 23 r = kzalloc(ops->rule_size, GFP_KERNEL); 24 if (r == NULL) 25 return -ENOMEM; 26 27 atomic_set(&r->refcnt, 1); 28 r->action = FR_ACT_TO_TBL; 29 r->pref = pref; 30 r->table = table; 31 r->flags = flags; 32 r->fr_net = ops->fro_net; 33 34 /* The lock is not required here, the list in unreacheable 35 * at the moment this function is called */ 36 list_add_tail(&r->list, &ops->rules_list); 37 return 0; 38 } 39 EXPORT_SYMBOL(fib_default_rule_add); 40 41 static void notify_rule_change(int event, struct fib_rule *rule, 42 struct fib_rules_ops *ops, struct nlmsghdr *nlh, 43 u32 pid); 44 45 static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family) 46 { 47 struct fib_rules_ops *ops; 48 49 rcu_read_lock(); 50 list_for_each_entry_rcu(ops, &net->rules_ops, list) { 51 if (ops->family == family) { 52 if (!try_module_get(ops->owner)) 53 ops = NULL; 54 rcu_read_unlock(); 55 return ops; 56 } 57 } 58 rcu_read_unlock(); 59 60 return NULL; 61 } 62 63 static void rules_ops_put(struct fib_rules_ops *ops) 64 { 65 if (ops) 66 module_put(ops->owner); 67 } 68 69 static void flush_route_cache(struct fib_rules_ops *ops) 70 { 71 if (ops->flush_cache) 72 ops->flush_cache(); 73 } 74 75 int fib_rules_register(struct fib_rules_ops *ops) 76 { 77 int err = -EEXIST; 78 struct fib_rules_ops *o; 79 struct net *net; 80 81 net = ops->fro_net; 82 83 if (ops->rule_size < sizeof(struct fib_rule)) 84 return -EINVAL; 85 86 if (ops->match == NULL || ops->configure == NULL || 87 ops->compare == NULL || ops->fill == NULL || 88 ops->action == NULL) 89 return -EINVAL; 90 91 spin_lock(&net->rules_mod_lock); 92 list_for_each_entry(o, &net->rules_ops, list) 93 if (ops->family == o->family) 94 goto errout; 95 96 hold_net(net); 97 list_add_tail_rcu(&ops->list, &net->rules_ops); 98 err = 0; 99 errout: 100 spin_unlock(&net->rules_mod_lock); 101 102 return err; 103 } 104 105 EXPORT_SYMBOL_GPL(fib_rules_register); 106 107 void fib_rules_cleanup_ops(struct fib_rules_ops *ops) 108 { 109 struct fib_rule *rule, *tmp; 110 111 list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) { 112 list_del_rcu(&rule->list); 113 fib_rule_put(rule); 114 } 115 } 116 EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops); 117 118 void fib_rules_unregister(struct fib_rules_ops *ops) 119 { 120 struct net *net = ops->fro_net; 121 122 spin_lock(&net->rules_mod_lock); 123 list_del_rcu(&ops->list); 124 fib_rules_cleanup_ops(ops); 125 spin_unlock(&net->rules_mod_lock); 126 127 synchronize_rcu(); 128 release_net(net); 129 } 130 131 EXPORT_SYMBOL_GPL(fib_rules_unregister); 132 133 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops, 134 struct flowi *fl, int flags) 135 { 136 int ret = 0; 137 138 if (rule->ifindex && (rule->ifindex != fl->iif)) 139 goto out; 140 141 if ((rule->mark ^ fl->mark) & rule->mark_mask) 142 goto out; 143 144 ret = ops->match(rule, fl, flags); 145 out: 146 return (rule->flags & FIB_RULE_INVERT) ? !ret : ret; 147 } 148 149 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl, 150 int flags, struct fib_lookup_arg *arg) 151 { 152 struct fib_rule *rule; 153 int err; 154 155 rcu_read_lock(); 156 157 list_for_each_entry_rcu(rule, &ops->rules_list, list) { 158 jumped: 159 if (!fib_rule_match(rule, ops, fl, flags)) 160 continue; 161 162 if (rule->action == FR_ACT_GOTO) { 163 struct fib_rule *target; 164 165 target = rcu_dereference(rule->ctarget); 166 if (target == NULL) { 167 continue; 168 } else { 169 rule = target; 170 goto jumped; 171 } 172 } else if (rule->action == FR_ACT_NOP) 173 continue; 174 else 175 err = ops->action(rule, fl, flags, arg); 176 177 if (err != -EAGAIN) { 178 fib_rule_get(rule); 179 arg->rule = rule; 180 goto out; 181 } 182 } 183 184 err = -ESRCH; 185 out: 186 rcu_read_unlock(); 187 188 return err; 189 } 190 191 EXPORT_SYMBOL_GPL(fib_rules_lookup); 192 193 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb, 194 struct fib_rules_ops *ops) 195 { 196 int err = -EINVAL; 197 198 if (frh->src_len) 199 if (tb[FRA_SRC] == NULL || 200 frh->src_len > (ops->addr_size * 8) || 201 nla_len(tb[FRA_SRC]) != ops->addr_size) 202 goto errout; 203 204 if (frh->dst_len) 205 if (tb[FRA_DST] == NULL || 206 frh->dst_len > (ops->addr_size * 8) || 207 nla_len(tb[FRA_DST]) != ops->addr_size) 208 goto errout; 209 210 err = 0; 211 errout: 212 return err; 213 } 214 215 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) 216 { 217 struct net *net = skb->sk->sk_net; 218 struct fib_rule_hdr *frh = nlmsg_data(nlh); 219 struct fib_rules_ops *ops = NULL; 220 struct fib_rule *rule, *r, *last = NULL; 221 struct nlattr *tb[FRA_MAX+1]; 222 int err = -EINVAL, unresolved = 0; 223 224 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) 225 goto errout; 226 227 ops = lookup_rules_ops(net, frh->family); 228 if (ops == NULL) { 229 err = EAFNOSUPPORT; 230 goto errout; 231 } 232 233 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy); 234 if (err < 0) 235 goto errout; 236 237 err = validate_rulemsg(frh, tb, ops); 238 if (err < 0) 239 goto errout; 240 241 rule = kzalloc(ops->rule_size, GFP_KERNEL); 242 if (rule == NULL) { 243 err = -ENOMEM; 244 goto errout; 245 } 246 rule->fr_net = net; 247 248 if (tb[FRA_PRIORITY]) 249 rule->pref = nla_get_u32(tb[FRA_PRIORITY]); 250 251 if (tb[FRA_IFNAME]) { 252 struct net_device *dev; 253 254 rule->ifindex = -1; 255 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ); 256 dev = __dev_get_by_name(net, rule->ifname); 257 if (dev) 258 rule->ifindex = dev->ifindex; 259 } 260 261 if (tb[FRA_FWMARK]) { 262 rule->mark = nla_get_u32(tb[FRA_FWMARK]); 263 if (rule->mark) 264 /* compatibility: if the mark value is non-zero all bits 265 * are compared unless a mask is explicitly specified. 266 */ 267 rule->mark_mask = 0xFFFFFFFF; 268 } 269 270 if (tb[FRA_FWMASK]) 271 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]); 272 273 rule->action = frh->action; 274 rule->flags = frh->flags; 275 rule->table = frh_get_table(frh, tb); 276 277 if (!rule->pref && ops->default_pref) 278 rule->pref = ops->default_pref(ops); 279 280 err = -EINVAL; 281 if (tb[FRA_GOTO]) { 282 if (rule->action != FR_ACT_GOTO) 283 goto errout_free; 284 285 rule->target = nla_get_u32(tb[FRA_GOTO]); 286 /* Backward jumps are prohibited to avoid endless loops */ 287 if (rule->target <= rule->pref) 288 goto errout_free; 289 290 list_for_each_entry(r, &ops->rules_list, list) { 291 if (r->pref == rule->target) { 292 rule->ctarget = r; 293 break; 294 } 295 } 296 297 if (rule->ctarget == NULL) 298 unresolved = 1; 299 } else if (rule->action == FR_ACT_GOTO) 300 goto errout_free; 301 302 err = ops->configure(rule, skb, nlh, frh, tb); 303 if (err < 0) 304 goto errout_free; 305 306 list_for_each_entry(r, &ops->rules_list, list) { 307 if (r->pref > rule->pref) 308 break; 309 last = r; 310 } 311 312 fib_rule_get(rule); 313 314 if (ops->unresolved_rules) { 315 /* 316 * There are unresolved goto rules in the list, check if 317 * any of them are pointing to this new rule. 318 */ 319 list_for_each_entry(r, &ops->rules_list, list) { 320 if (r->action == FR_ACT_GOTO && 321 r->target == rule->pref) { 322 BUG_ON(r->ctarget != NULL); 323 rcu_assign_pointer(r->ctarget, rule); 324 if (--ops->unresolved_rules == 0) 325 break; 326 } 327 } 328 } 329 330 if (rule->action == FR_ACT_GOTO) 331 ops->nr_goto_rules++; 332 333 if (unresolved) 334 ops->unresolved_rules++; 335 336 if (last) 337 list_add_rcu(&rule->list, &last->list); 338 else 339 list_add_rcu(&rule->list, &ops->rules_list); 340 341 notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid); 342 flush_route_cache(ops); 343 rules_ops_put(ops); 344 return 0; 345 346 errout_free: 347 kfree(rule); 348 errout: 349 rules_ops_put(ops); 350 return err; 351 } 352 353 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) 354 { 355 struct net *net = skb->sk->sk_net; 356 struct fib_rule_hdr *frh = nlmsg_data(nlh); 357 struct fib_rules_ops *ops = NULL; 358 struct fib_rule *rule, *tmp; 359 struct nlattr *tb[FRA_MAX+1]; 360 int err = -EINVAL; 361 362 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) 363 goto errout; 364 365 ops = lookup_rules_ops(net, frh->family); 366 if (ops == NULL) { 367 err = EAFNOSUPPORT; 368 goto errout; 369 } 370 371 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy); 372 if (err < 0) 373 goto errout; 374 375 err = validate_rulemsg(frh, tb, ops); 376 if (err < 0) 377 goto errout; 378 379 list_for_each_entry(rule, &ops->rules_list, list) { 380 if (frh->action && (frh->action != rule->action)) 381 continue; 382 383 if (frh->table && (frh_get_table(frh, tb) != rule->table)) 384 continue; 385 386 if (tb[FRA_PRIORITY] && 387 (rule->pref != nla_get_u32(tb[FRA_PRIORITY]))) 388 continue; 389 390 if (tb[FRA_IFNAME] && 391 nla_strcmp(tb[FRA_IFNAME], rule->ifname)) 392 continue; 393 394 if (tb[FRA_FWMARK] && 395 (rule->mark != nla_get_u32(tb[FRA_FWMARK]))) 396 continue; 397 398 if (tb[FRA_FWMASK] && 399 (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK]))) 400 continue; 401 402 if (!ops->compare(rule, frh, tb)) 403 continue; 404 405 if (rule->flags & FIB_RULE_PERMANENT) { 406 err = -EPERM; 407 goto errout; 408 } 409 410 list_del_rcu(&rule->list); 411 412 if (rule->action == FR_ACT_GOTO) 413 ops->nr_goto_rules--; 414 415 /* 416 * Check if this rule is a target to any of them. If so, 417 * disable them. As this operation is eventually very 418 * expensive, it is only performed if goto rules have 419 * actually been added. 420 */ 421 if (ops->nr_goto_rules > 0) { 422 list_for_each_entry(tmp, &ops->rules_list, list) { 423 if (tmp->ctarget == rule) { 424 rcu_assign_pointer(tmp->ctarget, NULL); 425 ops->unresolved_rules++; 426 } 427 } 428 } 429 430 synchronize_rcu(); 431 notify_rule_change(RTM_DELRULE, rule, ops, nlh, 432 NETLINK_CB(skb).pid); 433 fib_rule_put(rule); 434 flush_route_cache(ops); 435 rules_ops_put(ops); 436 return 0; 437 } 438 439 err = -ENOENT; 440 errout: 441 rules_ops_put(ops); 442 return err; 443 } 444 445 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops, 446 struct fib_rule *rule) 447 { 448 size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr)) 449 + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */ 450 + nla_total_size(4) /* FRA_PRIORITY */ 451 + nla_total_size(4) /* FRA_TABLE */ 452 + nla_total_size(4) /* FRA_FWMARK */ 453 + nla_total_size(4); /* FRA_FWMASK */ 454 455 if (ops->nlmsg_payload) 456 payload += ops->nlmsg_payload(rule); 457 458 return payload; 459 } 460 461 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule, 462 u32 pid, u32 seq, int type, int flags, 463 struct fib_rules_ops *ops) 464 { 465 struct nlmsghdr *nlh; 466 struct fib_rule_hdr *frh; 467 468 nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags); 469 if (nlh == NULL) 470 return -EMSGSIZE; 471 472 frh = nlmsg_data(nlh); 473 frh->table = rule->table; 474 NLA_PUT_U32(skb, FRA_TABLE, rule->table); 475 frh->res1 = 0; 476 frh->res2 = 0; 477 frh->action = rule->action; 478 frh->flags = rule->flags; 479 480 if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL) 481 frh->flags |= FIB_RULE_UNRESOLVED; 482 483 if (rule->ifname[0]) { 484 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname); 485 486 if (rule->ifindex == -1) 487 frh->flags |= FIB_RULE_DEV_DETACHED; 488 } 489 490 if (rule->pref) 491 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref); 492 493 if (rule->mark) 494 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark); 495 496 if (rule->mark_mask || rule->mark) 497 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask); 498 499 if (rule->target) 500 NLA_PUT_U32(skb, FRA_GOTO, rule->target); 501 502 if (ops->fill(rule, skb, nlh, frh) < 0) 503 goto nla_put_failure; 504 505 return nlmsg_end(skb, nlh); 506 507 nla_put_failure: 508 nlmsg_cancel(skb, nlh); 509 return -EMSGSIZE; 510 } 511 512 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb, 513 struct fib_rules_ops *ops) 514 { 515 int idx = 0; 516 struct fib_rule *rule; 517 518 list_for_each_entry(rule, &ops->rules_list, list) { 519 if (idx < cb->args[1]) 520 goto skip; 521 522 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid, 523 cb->nlh->nlmsg_seq, RTM_NEWRULE, 524 NLM_F_MULTI, ops) < 0) 525 break; 526 skip: 527 idx++; 528 } 529 cb->args[1] = idx; 530 rules_ops_put(ops); 531 532 return skb->len; 533 } 534 535 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb) 536 { 537 struct net *net = skb->sk->sk_net; 538 struct fib_rules_ops *ops; 539 int idx = 0, family; 540 541 family = rtnl_msg_family(cb->nlh); 542 if (family != AF_UNSPEC) { 543 /* Protocol specific dump request */ 544 ops = lookup_rules_ops(net, family); 545 if (ops == NULL) 546 return -EAFNOSUPPORT; 547 548 return dump_rules(skb, cb, ops); 549 } 550 551 rcu_read_lock(); 552 list_for_each_entry_rcu(ops, &net->rules_ops, list) { 553 if (idx < cb->args[0] || !try_module_get(ops->owner)) 554 goto skip; 555 556 if (dump_rules(skb, cb, ops) < 0) 557 break; 558 559 cb->args[1] = 0; 560 skip: 561 idx++; 562 } 563 rcu_read_unlock(); 564 cb->args[0] = idx; 565 566 return skb->len; 567 } 568 569 static void notify_rule_change(int event, struct fib_rule *rule, 570 struct fib_rules_ops *ops, struct nlmsghdr *nlh, 571 u32 pid) 572 { 573 struct net *net; 574 struct sk_buff *skb; 575 int err = -ENOBUFS; 576 577 net = ops->fro_net; 578 skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL); 579 if (skb == NULL) 580 goto errout; 581 582 err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops); 583 if (err < 0) { 584 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */ 585 WARN_ON(err == -EMSGSIZE); 586 kfree_skb(skb); 587 goto errout; 588 } 589 590 err = rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL); 591 errout: 592 if (err < 0) 593 rtnl_set_sk_err(net, ops->nlgroup, err); 594 } 595 596 static void attach_rules(struct list_head *rules, struct net_device *dev) 597 { 598 struct fib_rule *rule; 599 600 list_for_each_entry(rule, rules, list) { 601 if (rule->ifindex == -1 && 602 strcmp(dev->name, rule->ifname) == 0) 603 rule->ifindex = dev->ifindex; 604 } 605 } 606 607 static void detach_rules(struct list_head *rules, struct net_device *dev) 608 { 609 struct fib_rule *rule; 610 611 list_for_each_entry(rule, rules, list) 612 if (rule->ifindex == dev->ifindex) 613 rule->ifindex = -1; 614 } 615 616 617 static int fib_rules_event(struct notifier_block *this, unsigned long event, 618 void *ptr) 619 { 620 struct net_device *dev = ptr; 621 struct net *net = dev->nd_net; 622 struct fib_rules_ops *ops; 623 624 ASSERT_RTNL(); 625 rcu_read_lock(); 626 627 switch (event) { 628 case NETDEV_REGISTER: 629 list_for_each_entry(ops, &net->rules_ops, list) 630 attach_rules(&ops->rules_list, dev); 631 break; 632 633 case NETDEV_UNREGISTER: 634 list_for_each_entry(ops, &net->rules_ops, list) 635 detach_rules(&ops->rules_list, dev); 636 break; 637 } 638 639 rcu_read_unlock(); 640 641 return NOTIFY_DONE; 642 } 643 644 static struct notifier_block fib_rules_notifier = { 645 .notifier_call = fib_rules_event, 646 }; 647 648 static int fib_rules_net_init(struct net *net) 649 { 650 INIT_LIST_HEAD(&net->rules_ops); 651 spin_lock_init(&net->rules_mod_lock); 652 return 0; 653 } 654 655 static struct pernet_operations fib_rules_net_ops = { 656 .init = fib_rules_net_init, 657 }; 658 659 static int __init fib_rules_init(void) 660 { 661 int err; 662 rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL); 663 rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL); 664 rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule); 665 666 err = register_netdevice_notifier(&fib_rules_notifier); 667 if (err < 0) 668 goto fail; 669 670 err = register_pernet_subsys(&fib_rules_net_ops); 671 if (err < 0) 672 goto fail_unregister; 673 return 0; 674 675 fail_unregister: 676 unregister_netdevice_notifier(&fib_rules_notifier); 677 fail: 678 rtnl_unregister(PF_UNSPEC, RTM_NEWRULE); 679 rtnl_unregister(PF_UNSPEC, RTM_DELRULE); 680 rtnl_unregister(PF_UNSPEC, RTM_GETRULE); 681 return err; 682 } 683 684 subsys_initcall(fib_rules_init); 685