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 = hold_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(ops); 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 = sock_net(skb->sk); 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 = hold_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 release_net(rule->fr_net); 348 kfree(rule); 349 errout: 350 rules_ops_put(ops); 351 return err; 352 } 353 354 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) 355 { 356 struct net *net = sock_net(skb->sk); 357 struct fib_rule_hdr *frh = nlmsg_data(nlh); 358 struct fib_rules_ops *ops = NULL; 359 struct fib_rule *rule, *tmp; 360 struct nlattr *tb[FRA_MAX+1]; 361 int err = -EINVAL; 362 363 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) 364 goto errout; 365 366 ops = lookup_rules_ops(net, frh->family); 367 if (ops == NULL) { 368 err = -EAFNOSUPPORT; 369 goto errout; 370 } 371 372 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy); 373 if (err < 0) 374 goto errout; 375 376 err = validate_rulemsg(frh, tb, ops); 377 if (err < 0) 378 goto errout; 379 380 list_for_each_entry(rule, &ops->rules_list, list) { 381 if (frh->action && (frh->action != rule->action)) 382 continue; 383 384 if (frh->table && (frh_get_table(frh, tb) != rule->table)) 385 continue; 386 387 if (tb[FRA_PRIORITY] && 388 (rule->pref != nla_get_u32(tb[FRA_PRIORITY]))) 389 continue; 390 391 if (tb[FRA_IFNAME] && 392 nla_strcmp(tb[FRA_IFNAME], rule->ifname)) 393 continue; 394 395 if (tb[FRA_FWMARK] && 396 (rule->mark != nla_get_u32(tb[FRA_FWMARK]))) 397 continue; 398 399 if (tb[FRA_FWMASK] && 400 (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK]))) 401 continue; 402 403 if (!ops->compare(rule, frh, tb)) 404 continue; 405 406 if (rule->flags & FIB_RULE_PERMANENT) { 407 err = -EPERM; 408 goto errout; 409 } 410 411 list_del_rcu(&rule->list); 412 413 if (rule->action == FR_ACT_GOTO) 414 ops->nr_goto_rules--; 415 416 /* 417 * Check if this rule is a target to any of them. If so, 418 * disable them. As this operation is eventually very 419 * expensive, it is only performed if goto rules have 420 * actually been added. 421 */ 422 if (ops->nr_goto_rules > 0) { 423 list_for_each_entry(tmp, &ops->rules_list, list) { 424 if (tmp->ctarget == rule) { 425 rcu_assign_pointer(tmp->ctarget, NULL); 426 ops->unresolved_rules++; 427 } 428 } 429 } 430 431 synchronize_rcu(); 432 notify_rule_change(RTM_DELRULE, rule, ops, nlh, 433 NETLINK_CB(skb).pid); 434 fib_rule_put(rule); 435 flush_route_cache(ops); 436 rules_ops_put(ops); 437 return 0; 438 } 439 440 err = -ENOENT; 441 errout: 442 rules_ops_put(ops); 443 return err; 444 } 445 446 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops, 447 struct fib_rule *rule) 448 { 449 size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr)) 450 + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */ 451 + nla_total_size(4) /* FRA_PRIORITY */ 452 + nla_total_size(4) /* FRA_TABLE */ 453 + nla_total_size(4) /* FRA_FWMARK */ 454 + nla_total_size(4); /* FRA_FWMASK */ 455 456 if (ops->nlmsg_payload) 457 payload += ops->nlmsg_payload(rule); 458 459 return payload; 460 } 461 462 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule, 463 u32 pid, u32 seq, int type, int flags, 464 struct fib_rules_ops *ops) 465 { 466 struct nlmsghdr *nlh; 467 struct fib_rule_hdr *frh; 468 469 nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags); 470 if (nlh == NULL) 471 return -EMSGSIZE; 472 473 frh = nlmsg_data(nlh); 474 frh->table = rule->table; 475 NLA_PUT_U32(skb, FRA_TABLE, rule->table); 476 frh->res1 = 0; 477 frh->res2 = 0; 478 frh->action = rule->action; 479 frh->flags = rule->flags; 480 481 if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL) 482 frh->flags |= FIB_RULE_UNRESOLVED; 483 484 if (rule->ifname[0]) { 485 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname); 486 487 if (rule->ifindex == -1) 488 frh->flags |= FIB_RULE_DEV_DETACHED; 489 } 490 491 if (rule->pref) 492 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref); 493 494 if (rule->mark) 495 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark); 496 497 if (rule->mark_mask || rule->mark) 498 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask); 499 500 if (rule->target) 501 NLA_PUT_U32(skb, FRA_GOTO, rule->target); 502 503 if (ops->fill(rule, skb, nlh, frh) < 0) 504 goto nla_put_failure; 505 506 return nlmsg_end(skb, nlh); 507 508 nla_put_failure: 509 nlmsg_cancel(skb, nlh); 510 return -EMSGSIZE; 511 } 512 513 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb, 514 struct fib_rules_ops *ops) 515 { 516 int idx = 0; 517 struct fib_rule *rule; 518 519 list_for_each_entry(rule, &ops->rules_list, list) { 520 if (idx < cb->args[1]) 521 goto skip; 522 523 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid, 524 cb->nlh->nlmsg_seq, RTM_NEWRULE, 525 NLM_F_MULTI, ops) < 0) 526 break; 527 skip: 528 idx++; 529 } 530 cb->args[1] = idx; 531 rules_ops_put(ops); 532 533 return skb->len; 534 } 535 536 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb) 537 { 538 struct net *net = sock_net(skb->sk); 539 struct fib_rules_ops *ops; 540 int idx = 0, family; 541 542 family = rtnl_msg_family(cb->nlh); 543 if (family != AF_UNSPEC) { 544 /* Protocol specific dump request */ 545 ops = lookup_rules_ops(net, family); 546 if (ops == NULL) 547 return -EAFNOSUPPORT; 548 549 return dump_rules(skb, cb, ops); 550 } 551 552 rcu_read_lock(); 553 list_for_each_entry_rcu(ops, &net->rules_ops, list) { 554 if (idx < cb->args[0] || !try_module_get(ops->owner)) 555 goto skip; 556 557 if (dump_rules(skb, cb, ops) < 0) 558 break; 559 560 cb->args[1] = 0; 561 skip: 562 idx++; 563 } 564 rcu_read_unlock(); 565 cb->args[0] = idx; 566 567 return skb->len; 568 } 569 570 static void notify_rule_change(int event, struct fib_rule *rule, 571 struct fib_rules_ops *ops, struct nlmsghdr *nlh, 572 u32 pid) 573 { 574 struct net *net; 575 struct sk_buff *skb; 576 int err = -ENOBUFS; 577 578 net = ops->fro_net; 579 skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL); 580 if (skb == NULL) 581 goto errout; 582 583 err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops); 584 if (err < 0) { 585 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */ 586 WARN_ON(err == -EMSGSIZE); 587 kfree_skb(skb); 588 goto errout; 589 } 590 591 rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL); 592 return; 593 errout: 594 if (err < 0) 595 rtnl_set_sk_err(net, ops->nlgroup, err); 596 } 597 598 static void attach_rules(struct list_head *rules, struct net_device *dev) 599 { 600 struct fib_rule *rule; 601 602 list_for_each_entry(rule, rules, list) { 603 if (rule->ifindex == -1 && 604 strcmp(dev->name, rule->ifname) == 0) 605 rule->ifindex = dev->ifindex; 606 } 607 } 608 609 static void detach_rules(struct list_head *rules, struct net_device *dev) 610 { 611 struct fib_rule *rule; 612 613 list_for_each_entry(rule, rules, list) 614 if (rule->ifindex == dev->ifindex) 615 rule->ifindex = -1; 616 } 617 618 619 static int fib_rules_event(struct notifier_block *this, unsigned long event, 620 void *ptr) 621 { 622 struct net_device *dev = ptr; 623 struct net *net = dev_net(dev); 624 struct fib_rules_ops *ops; 625 626 ASSERT_RTNL(); 627 rcu_read_lock(); 628 629 switch (event) { 630 case NETDEV_REGISTER: 631 list_for_each_entry(ops, &net->rules_ops, list) 632 attach_rules(&ops->rules_list, dev); 633 break; 634 635 case NETDEV_UNREGISTER: 636 list_for_each_entry(ops, &net->rules_ops, list) 637 detach_rules(&ops->rules_list, dev); 638 break; 639 } 640 641 rcu_read_unlock(); 642 643 return NOTIFY_DONE; 644 } 645 646 static struct notifier_block fib_rules_notifier = { 647 .notifier_call = fib_rules_event, 648 }; 649 650 static int fib_rules_net_init(struct net *net) 651 { 652 INIT_LIST_HEAD(&net->rules_ops); 653 spin_lock_init(&net->rules_mod_lock); 654 return 0; 655 } 656 657 static struct pernet_operations fib_rules_net_ops = { 658 .init = fib_rules_net_init, 659 }; 660 661 static int __init fib_rules_init(void) 662 { 663 int err; 664 rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL); 665 rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL); 666 rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule); 667 668 err = register_pernet_subsys(&fib_rules_net_ops); 669 if (err < 0) 670 goto fail; 671 672 err = register_netdevice_notifier(&fib_rules_notifier); 673 if (err < 0) 674 goto fail_unregister; 675 676 return 0; 677 678 fail_unregister: 679 unregister_pernet_subsys(&fib_rules_net_ops); 680 fail: 681 rtnl_unregister(PF_UNSPEC, RTM_NEWRULE); 682 rtnl_unregister(PF_UNSPEC, RTM_DELRULE); 683 rtnl_unregister(PF_UNSPEC, RTM_GETRULE); 684 return err; 685 } 686 687 subsys_initcall(fib_rules_init); 688