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 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
  33         /* The lock is not required here, the list in unreacheable
  34          * at the moment this function is called */
  35         list_add_tail(&r->list, &ops->rules_list);
  36         return 0;
  37 }
  38 EXPORT_SYMBOL(fib_default_rule_add);
  39
  40 static void notify_rule_change(int event, struct fib_rule *rule,
  41                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
  42                                u32 pid);
  43
  44 static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
  45 {
  46         struct fib_rules_ops *ops;
  47
  48         rcu_read_lock();
  49         list_for_each_entry_rcu(ops, &net->rules_ops, list) {
  50                 if (ops->family == family) {
  51                         if (!try_module_get(ops->owner))
  52                                 ops = NULL;
  53                         rcu_read_unlock();
  54                         return ops;
  55                 }
  56         }
  57         rcu_read_unlock();
  58
  59         return NULL;
  60 }
  61
  62 static void rules_ops_put(struct fib_rules_ops *ops)
  63 {
  64         if (ops)
  65                 module_put(ops->owner);
  66 }
  67
  68 static void flush_route_cache(struct fib_rules_ops *ops)
  69 {
  70         if (ops->flush_cache)
  71                 ops->flush_cache();
  72 }
  73
  74 int fib_rules_register(struct fib_rules_ops *ops)
  75 {
  76         int err = -EEXIST;
  77         struct fib_rules_ops *o;
  78         struct net *net;
  79
  80         net = ops->fro_net;
  81
  82         if (ops->rule_size < sizeof(struct fib_rule))
  83                 return -EINVAL;
  84
  85         if (ops->match == NULL || ops->configure == NULL ||
  86             ops->compare == NULL || ops->fill == NULL ||
  87             ops->action == NULL)
  88                 return -EINVAL;
  89
  90         spin_lock(&net->rules_mod_lock);
  91         list_for_each_entry(o, &net->rules_ops, list)
  92                 if (ops->family == o->family)
  93                         goto errout;
  94
  95         hold_net(net);
  96         list_add_tail_rcu(&ops->list, &net->rules_ops);
  97         err = 0;
  98 errout:
  99         spin_unlock(&net->rules_mod_lock);
 100
 101         return err;
 102 }
 103
 104 EXPORT_SYMBOL_GPL(fib_rules_register);
 105
 106 void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
 107 {
 108         struct fib_rule *rule, *tmp;
 109
 110         list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
 111                 list_del_rcu(&rule->list);
 112                 fib_rule_put(rule);
 113         }
 114 }
 115 EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);
 116
 117 void fib_rules_unregister(struct fib_rules_ops *ops)
 118 {
 119         struct net *net = ops->fro_net;
 120
 121         spin_lock(&net->rules_mod_lock);
 122         list_del_rcu(&ops->list);
 123         fib_rules_cleanup_ops(ops);
 124         spin_unlock(&net->rules_mod_lock);
 125
 126         synchronize_rcu();
 127         release_net(net);
 128 }
 129
 130 EXPORT_SYMBOL_GPL(fib_rules_unregister);
 131
 132 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 133                           struct flowi *fl, int flags)
 134 {
 135         int ret = 0;
 136
 137         if (rule->ifindex && (rule->ifindex != fl->iif))
 138                 goto out;
 139
 140         if ((rule->mark ^ fl->mark) & rule->mark_mask)
 141                 goto out;
 142
 143         ret = ops->match(rule, fl, flags);
 144 out:
 145         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
 146 }
 147
 148 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 149                      int flags, struct fib_lookup_arg *arg)
 150 {
 151         struct fib_rule *rule;
 152         int err;
 153
 154         rcu_read_lock();
 155
 156         list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 157 jumped:
 158                 if (!fib_rule_match(rule, ops, fl, flags))
 159                         continue;
 160
 161                 if (rule->action == FR_ACT_GOTO) {
 162                         struct fib_rule *target;
 163
 164                         target = rcu_dereference(rule->ctarget);
 165                         if (target == NULL) {
 166                                 continue;
 167                         } else {
 168                                 rule = target;
 169                                 goto jumped;
 170                         }
 171                 } else if (rule->action == FR_ACT_NOP)
 172                         continue;
 173                 else
 174                         err = ops->action(rule, fl, flags, arg);
 175
 176                 if (err != -EAGAIN) {
 177                         fib_rule_get(rule);
 178                         arg->rule = rule;
 179                         goto out;
 180                 }
 181         }
 182
 183         err = -ESRCH;
 184 out:
 185         rcu_read_unlock();
 186
 187         return err;
 188 }
 189
 190 EXPORT_SYMBOL_GPL(fib_rules_lookup);
 191
 192 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 193                             struct fib_rules_ops *ops)
 194 {
 195         int err = -EINVAL;
 196
 197         if (frh->src_len)
 198                 if (tb[FRA_SRC] == NULL ||
 199                     frh->src_len > (ops->addr_size * 8) ||
 200                     nla_len(tb[FRA_SRC]) != ops->addr_size)
 201                         goto errout;
 202
 203         if (frh->dst_len)
 204                 if (tb[FRA_DST] == NULL ||
 205                     frh->dst_len > (ops->addr_size * 8) ||
 206                     nla_len(tb[FRA_DST]) != ops->addr_size)
 207                         goto errout;
 208
 209         err = 0;
 210 errout:
 211         return err;
 212 }
 213
 214 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 215 {
 216         struct net *net = skb->sk->sk_net;
 217         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 218         struct fib_rules_ops *ops = NULL;
 219         struct fib_rule *rule, *r, *last = NULL;
 220         struct nlattr *tb[FRA_MAX+1];
 221         int err = -EINVAL, unresolved = 0;
 222
 223         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 224                 goto errout;
 225
 226         ops = lookup_rules_ops(net, frh->family);
 227         if (ops == NULL) {
 228                 err = EAFNOSUPPORT;
 229                 goto errout;
 230         }
 231
 232         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 233         if (err < 0)
 234                 goto errout;
 235
 236         err = validate_rulemsg(frh, tb, ops);
 237         if (err < 0)
 238                 goto errout;
 239
 240         rule = kzalloc(ops->rule_size, GFP_KERNEL);
 241         if (rule == NULL) {
 242                 err = -ENOMEM;
 243                 goto errout;
 244         }
 245
 246         if (tb[FRA_PRIORITY])
 247                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 248
 249         if (tb[FRA_IFNAME]) {
 250                 struct net_device *dev;
 251
 252                 rule->ifindex = -1;
 253                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 254                 dev = __dev_get_by_name(net, rule->ifname);
 255                 if (dev)
 256                         rule->ifindex = dev->ifindex;
 257         }
 258
 259         if (tb[FRA_FWMARK]) {
 260                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 261                 if (rule->mark)
 262                         /* compatibility: if the mark value is non-zero all bits
 263                          * are compared unless a mask is explicitly specified.
 264                          */
 265                         rule->mark_mask = 0xFFFFFFFF;
 266         }
 267
 268         if (tb[FRA_FWMASK])
 269                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 270
 271         rule->action = frh->action;
 272         rule->flags = frh->flags;
 273         rule->table = frh_get_table(frh, tb);
 274
 275         if (!rule->pref && ops->default_pref)
 276                 rule->pref = ops->default_pref(ops);
 277
 278         err = -EINVAL;
 279         if (tb[FRA_GOTO]) {
 280                 if (rule->action != FR_ACT_GOTO)
 281                         goto errout_free;
 282
 283                 rule->target = nla_get_u32(tb[FRA_GOTO]);
 284                 /* Backward jumps are prohibited to avoid endless loops */
 285                 if (rule->target <= rule->pref)
 286                         goto errout_free;
 287
 288                 list_for_each_entry(r, &ops->rules_list, list) {
 289                         if (r->pref == rule->target) {
 290                                 rule->ctarget = r;
 291                                 break;
 292                         }
 293                 }
 294
 295                 if (rule->ctarget == NULL)
 296                         unresolved = 1;
 297         } else if (rule->action == FR_ACT_GOTO)
 298                 goto errout_free;
 299
 300         err = ops->configure(rule, skb, nlh, frh, tb);
 301         if (err < 0)
 302                 goto errout_free;
 303
 304         list_for_each_entry(r, &ops->rules_list, list) {
 305                 if (r->pref > rule->pref)
 306                         break;
 307                 last = r;
 308         }
 309
 310         fib_rule_get(rule);
 311
 312         if (ops->unresolved_rules) {
 313                 /*
 314                  * There are unresolved goto rules in the list, check if
 315                  * any of them are pointing to this new rule.
 316                  */
 317                 list_for_each_entry(r, &ops->rules_list, list) {
 318                         if (r->action == FR_ACT_GOTO &&
 319                             r->target == rule->pref) {
 320                                 BUG_ON(r->ctarget != NULL);
 321                                 rcu_assign_pointer(r->ctarget, rule);
 322                                 if (--ops->unresolved_rules == 0)
 323                                         break;
 324                         }
 325                 }
 326         }
 327
 328         if (rule->action == FR_ACT_GOTO)
 329                 ops->nr_goto_rules++;
 330
 331         if (unresolved)
 332                 ops->unresolved_rules++;
 333
 334         if (last)
 335                 list_add_rcu(&rule->list, &last->list);
 336         else
 337                 list_add_rcu(&rule->list, &ops->rules_list);
 338
 339         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 340         flush_route_cache(ops);
 341         rules_ops_put(ops);
 342         return 0;
 343
 344 errout_free:
 345         kfree(rule);
 346 errout:
 347         rules_ops_put(ops);
 348         return err;
 349 }
 350
 351 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 352 {
 353         struct net *net = skb->sk->sk_net;
 354         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 355         struct fib_rules_ops *ops = NULL;
 356         struct fib_rule *rule, *tmp;
 357         struct nlattr *tb[FRA_MAX+1];
 358         int err = -EINVAL;
 359
 360         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 361                 goto errout;
 362
 363         ops = lookup_rules_ops(net, frh->family);
 364         if (ops == NULL) {
 365                 err = EAFNOSUPPORT;
 366                 goto errout;
 367         }
 368
 369         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 370         if (err < 0)
 371                 goto errout;
 372
 373         err = validate_rulemsg(frh, tb, ops);
 374         if (err < 0)
 375                 goto errout;
 376
 377         list_for_each_entry(rule, &ops->rules_list, list) {
 378                 if (frh->action && (frh->action != rule->action))
 379                         continue;
 380
 381                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
 382                         continue;
 383
 384                 if (tb[FRA_PRIORITY] &&
 385                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 386                         continue;
 387
 388                 if (tb[FRA_IFNAME] &&
 389                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 390                         continue;
 391
 392                 if (tb[FRA_FWMARK] &&
 393                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 394                         continue;
 395
 396                 if (tb[FRA_FWMASK] &&
 397                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 398                         continue;
 399
 400                 if (!ops->compare(rule, frh, tb))
 401                         continue;
 402
 403                 if (rule->flags & FIB_RULE_PERMANENT) {
 404                         err = -EPERM;
 405                         goto errout;
 406                 }
 407
 408                 list_del_rcu(&rule->list);
 409
 410                 if (rule->action == FR_ACT_GOTO)
 411                         ops->nr_goto_rules--;
 412
 413                 /*
 414                  * Check if this rule is a target to any of them. If so,
 415                  * disable them. As this operation is eventually very
 416                  * expensive, it is only performed if goto rules have
 417                  * actually been added.
 418                  */
 419                 if (ops->nr_goto_rules > 0) {
 420                         list_for_each_entry(tmp, &ops->rules_list, list) {
 421                                 if (tmp->ctarget == rule) {
 422                                         rcu_assign_pointer(tmp->ctarget, NULL);
 423                                         ops->unresolved_rules++;
 424                                 }
 425                         }
 426                 }
 427
 428                 synchronize_rcu();
 429                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 430                                    NETLINK_CB(skb).pid);
 431                 fib_rule_put(rule);
 432                 flush_route_cache(ops);
 433                 rules_ops_put(ops);
 434                 return 0;
 435         }
 436
 437         err = -ENOENT;
 438 errout:
 439         rules_ops_put(ops);
 440         return err;
 441 }
 442
 443 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 444                                          struct fib_rule *rule)
 445 {
 446         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 447                          + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
 448                          + nla_total_size(4) /* FRA_PRIORITY */
 449                          + nla_total_size(4) /* FRA_TABLE */
 450                          + nla_total_size(4) /* FRA_FWMARK */
 451                          + nla_total_size(4); /* FRA_FWMASK */
 452
 453         if (ops->nlmsg_payload)
 454                 payload += ops->nlmsg_payload(rule);
 455
 456         return payload;
 457 }
 458
 459 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 460                             u32 pid, u32 seq, int type, int flags,
 461                             struct fib_rules_ops *ops)
 462 {
 463         struct nlmsghdr *nlh;
 464         struct fib_rule_hdr *frh;
 465
 466         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 467         if (nlh == NULL)
 468                 return -EMSGSIZE;
 469
 470         frh = nlmsg_data(nlh);
 471         frh->table = rule->table;
 472         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 473         frh->res1 = 0;
 474         frh->res2 = 0;
 475         frh->action = rule->action;
 476         frh->flags = rule->flags;
 477
 478         if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
 479                 frh->flags |= FIB_RULE_UNRESOLVED;
 480
 481         if (rule->ifname[0]) {
 482                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 483
 484                 if (rule->ifindex == -1)
 485                         frh->flags |= FIB_RULE_DEV_DETACHED;
 486         }
 487
 488         if (rule->pref)
 489                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 490
 491         if (rule->mark)
 492                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 493
 494         if (rule->mark_mask || rule->mark)
 495                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 496
 497         if (rule->target)
 498                 NLA_PUT_U32(skb, FRA_GOTO, rule->target);
 499
 500         if (ops->fill(rule, skb, nlh, frh) < 0)
 501                 goto nla_put_failure;
 502
 503         return nlmsg_end(skb, nlh);
 504
 505 nla_put_failure:
 506         nlmsg_cancel(skb, nlh);
 507         return -EMSGSIZE;
 508 }
 509
 510 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
 511                       struct fib_rules_ops *ops)
 512 {
 513         int idx = 0;
 514         struct fib_rule *rule;
 515
 516         list_for_each_entry(rule, &ops->rules_list, list) {
 517                 if (idx < cb->args[1])
 518                         goto skip;
 519
 520                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 521                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 522                                      NLM_F_MULTI, ops) < 0)
 523                         break;
 524 skip:
 525                 idx++;
 526         }
 527         cb->args[1] = idx;
 528         rules_ops_put(ops);
 529
 530         return skb->len;
 531 }
 532
 533 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
 534 {
 535         struct net *net = skb->sk->sk_net;
 536         struct fib_rules_ops *ops;
 537         int idx = 0, family;
 538
 539         family = rtnl_msg_family(cb->nlh);
 540         if (family != AF_UNSPEC) {
 541                 /* Protocol specific dump request */
 542                 ops = lookup_rules_ops(net, family);
 543                 if (ops == NULL)
 544                         return -EAFNOSUPPORT;
 545
 546                 return dump_rules(skb, cb, ops);
 547         }
 548
 549         rcu_read_lock();
 550         list_for_each_entry_rcu(ops, &net->rules_ops, list) {
 551                 if (idx < cb->args[0] || !try_module_get(ops->owner))
 552                         goto skip;
 553
 554                 if (dump_rules(skb, cb, ops) < 0)
 555                         break;
 556
 557                 cb->args[1] = 0;
 558         skip:
 559                 idx++;
 560         }
 561         rcu_read_unlock();
 562         cb->args[0] = idx;
 563
 564         return skb->len;
 565 }
 566
 567 static void notify_rule_change(int event, struct fib_rule *rule,
 568                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 569                                u32 pid)
 570 {
 571         struct net *net;
 572         struct sk_buff *skb;
 573         int err = -ENOBUFS;
 574
 575         net = ops->fro_net;
 576         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 577         if (skb == NULL)
 578                 goto errout;
 579
 580         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 581         if (err < 0) {
 582                 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
 583                 WARN_ON(err == -EMSGSIZE);
 584                 kfree_skb(skb);
 585                 goto errout;
 586         }
 587
 588         err = rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
 589 errout:
 590         if (err < 0)
 591                 rtnl_set_sk_err(net, 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 net *net = dev->nd_net;
 620         struct fib_rules_ops *ops;
 621
 622         ASSERT_RTNL();
 623         rcu_read_lock();
 624
 625         switch (event) {
 626         case NETDEV_REGISTER:
 627                 list_for_each_entry(ops, &net->rules_ops, list)
 628                         attach_rules(&ops->rules_list, dev);
 629                 break;
 630
 631         case NETDEV_UNREGISTER:
 632                 list_for_each_entry(ops, &net->rules_ops, list)
 633                         detach_rules(&ops->rules_list, dev);
 634                 break;
 635         }
 636
 637         rcu_read_unlock();
 638
 639         return NOTIFY_DONE;
 640 }
 641
 642 static struct notifier_block fib_rules_notifier = {
 643         .notifier_call = fib_rules_event,
 644 };
 645
 646 static int fib_rules_net_init(struct net *net)
 647 {
 648         INIT_LIST_HEAD(&net->rules_ops);
 649         spin_lock_init(&net->rules_mod_lock);
 650         return 0;
 651 }
 652
 653 static struct pernet_operations fib_rules_net_ops = {
 654         .init = fib_rules_net_init,
 655 };
 656
 657 static int __init fib_rules_init(void)
 658 {
 659         int err;
 660         rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
 661         rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
 662         rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
 663
 664         err = register_netdevice_notifier(&fib_rules_notifier);
 665         if (err < 0)
 666                 goto fail;
 667
 668         err = register_pernet_subsys(&fib_rules_net_ops);
 669         if (err < 0)
 670                 goto fail_unregister;
 671         return 0;
 672
 673 fail_unregister:
 674         unregister_netdevice_notifier(&fib_rules_notifier);
 675 fail:
 676         rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
 677         rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
 678         rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
 679         return err;
 680 }
 681
 682 subsys_initcall(fib_rules_init);