net/core/fib_rules.c

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