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