release/src-rt/linux/linux-2.6/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 int fib_default_rule_add(struct fib_rules_ops *ops,
  20                          u32 pref, u32 table, u32 flags)
  21 {
  22         struct fib_rule *r;
  23
  24         r = kzalloc(ops->rule_size, GFP_KERNEL);
  25         if (r == NULL)
  26                 return -ENOMEM;
  27
  28         atomic_set(&r->refcnt, 1);
  29         r->action = FR_ACT_TO_TBL;
  30         r->pref = pref;
  31         r->table = table;
  32         r->flags = flags;
  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(int family)
  46 {
  47         struct fib_rules_ops *ops;
  48
  49         rcu_read_lock();
  50         list_for_each_entry_rcu(ops, &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
  80         if (ops->rule_size < sizeof(struct fib_rule))
  81                 return -EINVAL;
  82
  83         if (ops->match == NULL || ops->configure == NULL ||
  84             ops->compare == NULL || ops->fill == NULL ||
  85             ops->action == NULL)
  86                 return -EINVAL;
  87
  88         spin_lock(&rules_mod_lock);
  89         list_for_each_entry(o, &rules_ops, list)
  90                 if (ops->family == o->family)
  91                         goto errout;
  92
  93         list_add_tail_rcu(&ops->list, &rules_ops);
  94         err = 0;
  95 errout:
  96         spin_unlock(&rules_mod_lock);
  97
  98         return err;
  99 }
 100
 101 EXPORT_SYMBOL_GPL(fib_rules_register);
 102
 103 static void cleanup_ops(struct fib_rules_ops *ops)
 104 {
 105         struct fib_rule *rule, *tmp;
 106
 107         list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
 108                 list_del_rcu(&rule->list);
 109                 fib_rule_put(rule);
 110         }
 111 }
 112
 113 int fib_rules_unregister(struct fib_rules_ops *ops)
 114 {
 115         int err = 0;
 116         struct fib_rules_ops *o;
 117
 118         spin_lock(&rules_mod_lock);
 119         list_for_each_entry(o, &rules_ops, list) {
 120                 if (o == ops) {
 121                         list_del_rcu(&o->list);
 122                         cleanup_ops(ops);
 123                         goto out;
 124                 }
 125         }
 126
 127         err = -ENOENT;
 128 out:
 129         spin_unlock(&rules_mod_lock);
 130
 131         synchronize_rcu();
 132
 133         return err;
 134 }
 135
 136 EXPORT_SYMBOL_GPL(fib_rules_unregister);
 137
 138 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 139                           struct flowi *fl, int flags)
 140 {
 141         int ret = 0;
 142
 143         if (rule->ifindex && (rule->ifindex != fl->iif))
 144                 goto out;
 145
 146         if ((rule->mark ^ fl->mark) & rule->mark_mask)
 147                 goto out;
 148
 149         ret = ops->match(rule, fl, flags);
 150 out:
 151         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
 152 }
 153
 154 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 155                      int flags, struct fib_lookup_arg *arg)
 156 {
 157         struct fib_rule *rule;
 158         int err;
 159
 160         rcu_read_lock();
 161
 162         list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 163 jumped:
 164                 if (!fib_rule_match(rule, ops, fl, flags))
 165                         continue;
 166
 167                 if (rule->action == FR_ACT_GOTO) {
 168                         struct fib_rule *target;
 169
 170                         target = rcu_dereference(rule->ctarget);
 171                         if (target == NULL) {
 172                                 continue;
 173                         } else {
 174                                 rule = target;
 175                                 goto jumped;
 176                         }
 177                 } else if (rule->action == FR_ACT_NOP)
 178                         continue;
 179                 else
 180                         err = ops->action(rule, fl, flags, arg);
 181
 182                 if (err != -EAGAIN) {
 183                         fib_rule_get(rule);
 184                         arg->rule = rule;
 185                         goto out;
 186                 }
 187         }
 188
 189         err = -ESRCH;
 190 out:
 191         rcu_read_unlock();
 192
 193         return err;
 194 }
 195
 196 EXPORT_SYMBOL_GPL(fib_rules_lookup);
 197
 198 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 199                             struct fib_rules_ops *ops)
 200 {
 201         int err = -EINVAL;
 202
 203         if (frh->src_len)
 204                 if (tb[FRA_SRC] == NULL ||
 205                     frh->src_len > (ops->addr_size * 8) ||
 206                     nla_len(tb[FRA_SRC]) != ops->addr_size)
 207                         goto errout;
 208
 209         if (frh->dst_len)
 210                 if (tb[FRA_DST] == NULL ||
 211                     frh->dst_len > (ops->addr_size * 8) ||
 212                     nla_len(tb[FRA_DST]) != ops->addr_size)
 213                         goto errout;
 214
 215         err = 0;
 216 errout:
 217         return err;
 218 }
 219
 220 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 221 {
 222         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 223         struct fib_rules_ops *ops = NULL;
 224         struct fib_rule *rule, *r, *last = NULL;
 225         struct nlattr *tb[FRA_MAX+1];
 226         int err = -EINVAL, unresolved = 0;
 227
 228         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 229                 goto errout;
 230
 231         ops = lookup_rules_ops(frh->family);
 232         if (ops == NULL) {
 233                 err = EAFNOSUPPORT;
 234                 goto errout;
 235         }
 236
 237         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 238         if (err < 0)
 239                 goto errout;
 240
 241         err = validate_rulemsg(frh, tb, ops);
 242         if (err < 0)
 243                 goto errout;
 244
 245         rule = kzalloc(ops->rule_size, GFP_KERNEL);
 246         if (rule == NULL) {
 247                 err = -ENOMEM;
 248                 goto errout;
 249         }
 250
 251         if (tb[FRA_PRIORITY])
 252                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 253
 254         if (tb[FRA_IFNAME]) {
 255                 struct net_device *dev;
 256
 257                 rule->ifindex = -1;
 258                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 259                 dev = __dev_get_by_name(rule->ifname);
 260                 if (dev)
 261                         rule->ifindex = dev->ifindex;
 262         }
 263
 264         if (tb[FRA_FWMARK]) {
 265                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 266                 if (rule->mark)
 267                         /* compatibility: if the mark value is non-zero all bits
 268                          * are compared unless a mask is explicitly specified.
 269                          */
 270                         rule->mark_mask = 0xFFFFFFFF;
 271         }
 272
 273         if (tb[FRA_FWMASK])
 274                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 275
 276         rule->action = frh->action;
 277         rule->flags = frh->flags;
 278         rule->table = frh_get_table(frh, tb);
 279
 280         if (!rule->pref && ops->default_pref)
 281                 rule->pref = ops->default_pref();
 282
 283         err = -EINVAL;
 284         if (tb[FRA_GOTO]) {
 285                 if (rule->action != FR_ACT_GOTO)
 286                         goto errout_free;
 287
 288                 rule->target = nla_get_u32(tb[FRA_GOTO]);
 289                 /* Backward jumps are prohibited to avoid endless loops */
 290                 if (rule->target <= rule->pref)
 291                         goto errout_free;
 292
 293                 list_for_each_entry(r, &ops->rules_list, list) {
 294                         if (r->pref == rule->target) {
 295                                 rule->ctarget = r;
 296                                 break;
 297                         }
 298                 }
 299
 300                 if (rule->ctarget == NULL)
 301                         unresolved = 1;
 302         } else if (rule->action == FR_ACT_GOTO)
 303                 goto errout_free;
 304
 305         err = ops->configure(rule, skb, nlh, frh, tb);
 306         if (err < 0)
 307                 goto errout_free;
 308
 309         list_for_each_entry(r, &ops->rules_list, list) {
 310                 if (r->pref > rule->pref)
 311                         break;
 312                 last = r;
 313         }
 314
 315         fib_rule_get(rule);
 316
 317         if (ops->unresolved_rules) {
 318                 /*
 319                  * There are unresolved goto rules in the list, check if
 320                  * any of them are pointing to this new rule.
 321                  */
 322                 list_for_each_entry(r, &ops->rules_list, list) {
 323                         if (r->action == FR_ACT_GOTO &&
 324                             r->target == rule->pref) {
 325                                 BUG_ON(r->ctarget != NULL);
 326                                 rcu_assign_pointer(r->ctarget, rule);
 327                                 if (--ops->unresolved_rules == 0)
 328                                         break;
 329                         }
 330                 }
 331         }
 332
 333         if (rule->action == FR_ACT_GOTO)
 334                 ops->nr_goto_rules++;
 335
 336         if (unresolved)
 337                 ops->unresolved_rules++;
 338
 339         if (last)
 340                 list_add_rcu(&rule->list, &last->list);
 341         else
 342                 list_add_rcu(&rule->list, &ops->rules_list);
 343
 344         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 345         flush_route_cache(ops);
 346         rules_ops_put(ops);
 347         return 0;
 348
 349 errout_free:
 350         kfree(rule);
 351 errout:
 352         rules_ops_put(ops);
 353         return err;
 354 }
 355
 356 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 357 {
 358         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 359         struct fib_rules_ops *ops = NULL;
 360         struct fib_rule *rule, *tmp;
 361         struct nlattr *tb[FRA_MAX+1];
 362         int err = -EINVAL;
 363
 364         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 365                 goto errout;
 366
 367         ops = lookup_rules_ops(frh->family);
 368         if (ops == NULL) {
 369                 err = EAFNOSUPPORT;
 370                 goto errout;
 371         }
 372
 373         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 374         if (err < 0)
 375                 goto errout;
 376
 377         err = validate_rulemsg(frh, tb, ops);
 378         if (err < 0)
 379                 goto errout;
 380
 381         list_for_each_entry(rule, &ops->rules_list, list) {
 382                 if (frh->action && (frh->action != rule->action))
 383                         continue;
 384
 385                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
 386                         continue;
 387
 388                 if (tb[FRA_PRIORITY] &&
 389                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 390                         continue;
 391
 392                 if (tb[FRA_IFNAME] &&
 393                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 394                         continue;
 395
 396                 if (tb[FRA_FWMARK] &&
 397                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 398                         continue;
 399
 400                 if (tb[FRA_FWMASK] &&
 401                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 402                         continue;
 403
 404                 if (!ops->compare(rule, frh, tb))
 405                         continue;
 406
 407                 if (rule->flags & FIB_RULE_PERMANENT) {
 408                         err = -EPERM;
 409                         goto errout;
 410                 }
 411
 412                 list_del_rcu(&rule->list);
 413
 414                 if (rule->action == FR_ACT_GOTO)
 415                         ops->nr_goto_rules--;
 416
 417                 /*
 418                  * Check if this rule is a target to any of them. If so,
 419                  * disable them. As this operation is eventually very
 420                  * expensive, it is only performed if goto rules have
 421                  * actually been added.
 422                  */
 423                 if (ops->nr_goto_rules > 0) {
 424                         list_for_each_entry(tmp, &ops->rules_list, list) {
 425                                 if (tmp->ctarget == rule) {
 426                                         rcu_assign_pointer(tmp->ctarget, NULL);
 427                                         ops->unresolved_rules++;
 428                                 }
 429                         }
 430                 }
 431
 432                 synchronize_rcu();
 433                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 434                                    NETLINK_CB(skb).pid);
 435                 fib_rule_put(rule);
 436                 flush_route_cache(ops);
 437                 rules_ops_put(ops);
 438                 return 0;
 439         }
 440
 441         err = -ENOENT;
 442 errout:
 443         rules_ops_put(ops);
 444         return err;
 445 }
 446
 447 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 448                                          struct fib_rule *rule)
 449 {
 450         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 451                          + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
 452                          + nla_total_size(4) /* FRA_PRIORITY */
 453                          + nla_total_size(4) /* FRA_TABLE */
 454                          + nla_total_size(4) /* FRA_FWMARK */
 455                          + nla_total_size(4); /* FRA_FWMASK */
 456
 457         if (ops->nlmsg_payload)
 458                 payload += ops->nlmsg_payload(rule);
 459
 460         return payload;
 461 }
 462
 463 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 464                             u32 pid, u32 seq, int type, int flags,
 465                             struct fib_rules_ops *ops)
 466 {
 467         struct nlmsghdr *nlh;
 468         struct fib_rule_hdr *frh;
 469
 470         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 471         if (nlh == NULL)
 472                 return -EMSGSIZE;
 473
 474         frh = nlmsg_data(nlh);
 475         frh->table = rule->table;
 476         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 477         frh->res1 = 0;
 478         frh->res2 = 0;
 479         frh->action = rule->action;
 480         frh->flags = rule->flags;
 481
 482         if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
 483                 frh->flags |= FIB_RULE_UNRESOLVED;
 484
 485         if (rule->ifname[0]) {
 486                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 487
 488                 if (rule->ifindex == -1)
 489                         frh->flags |= FIB_RULE_DEV_DETACHED;
 490         }
 491
 492         if (rule->pref)
 493                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 494
 495         if (rule->mark)
 496                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 497
 498         if (rule->mark_mask || rule->mark)
 499                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 500
 501         if (rule->target)
 502                 NLA_PUT_U32(skb, FRA_GOTO, rule->target);
 503
 504         if (ops->fill(rule, skb, nlh, frh) < 0)
 505                 goto nla_put_failure;
 506
 507         return nlmsg_end(skb, nlh);
 508
 509 nla_put_failure:
 510         nlmsg_cancel(skb, nlh);
 511         return -EMSGSIZE;
 512 }
 513
 514 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
 515                       struct fib_rules_ops *ops)
 516 {
 517         int idx = 0;
 518         struct fib_rule *rule;
 519
 520         list_for_each_entry(rule, &ops->rules_list, list) {
 521                 if (idx < cb->args[1])
 522                         goto skip;
 523
 524                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 525                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 526                                      NLM_F_MULTI, ops) < 0)
 527                         break;
 528 skip:
 529                 idx++;
 530         }
 531         cb->args[1] = idx;
 532         rules_ops_put(ops);
 533
 534         return skb->len;
 535 }
 536
 537 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
 538 {
 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(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, &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 sk_buff *skb;
 575         int err = -ENOBUFS;
 576
 577         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 578         if (skb == NULL)
 579                 goto errout;
 580
 581         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 582         if (err < 0) {
 583                 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
 584                 WARN_ON(err == -EMSGSIZE);
 585                 kfree_skb(skb);
 586                 goto errout;
 587         }
 588         err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
 589 errout:
 590         if (err < 0)
 591                 rtnl_set_sk_err(ops->nlgroup, err);
 592 }
 593
 594 static void attach_rules(struct list_head *rules, struct net_device *dev)
 595 {
 596         struct fib_rule *rule;
 597
 598         list_for_each_entry(rule, rules, list) {
 599                 if (rule->ifindex == -1 &&
 600                     strcmp(dev->name, rule->ifname) == 0)
 601                         rule->ifindex = dev->ifindex;
 602         }
 603 }
 604
 605 static void detach_rules(struct list_head *rules, struct net_device *dev)
 606 {
 607         struct fib_rule *rule;
 608
 609         list_for_each_entry(rule, rules, list)
 610                 if (rule->ifindex == dev->ifindex)
 611                         rule->ifindex = -1;
 612 }
 613
 614
 615 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 616                             void *ptr)
 617 {
 618         struct net_device *dev = ptr;
 619         struct fib_rules_ops *ops;
 620
 621         ASSERT_RTNL();
 622         rcu_read_lock();
 623
 624         switch (event) {
 625         case NETDEV_REGISTER:
 626                 list_for_each_entry(ops, &rules_ops, list)
 627                         attach_rules(&ops->rules_list, dev);
 628                 break;
 629
 630         case NETDEV_UNREGISTER:
 631                 list_for_each_entry(ops, &rules_ops, list)
 632                         detach_rules(&ops->rules_list, dev);
 633                 break;
 634         }
 635
 636         rcu_read_unlock();
 637
 638         return NOTIFY_DONE;
 639 }
 640
 641 static struct notifier_block fib_rules_notifier = {
 642         .notifier_call = fib_rules_event,
 643 };
 644
 645 static int __init fib_rules_init(void)
 646 {
 647         rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
 648         rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
 649         rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
 650
 651         return register_netdevice_notifier(&fib_rules_notifier);
 652 }
 653
 654 subsys_initcall(fib_rules_init);