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