linux/net/core/fib_rules.c
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   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
  18int 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        r->fr_net = hold_net(ops->fro_net);
  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}
  39EXPORT_SYMBOL(fib_default_rule_add);
  40
  41static void notify_rule_change(int event, struct fib_rule *rule,
  42                               struct fib_rules_ops *ops, struct nlmsghdr *nlh,
  43                               u32 pid);
  44
  45static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
  46{
  47        struct fib_rules_ops *ops;
  48
  49        rcu_read_lock();
  50        list_for_each_entry_rcu(ops, &net->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
  63static void rules_ops_put(struct fib_rules_ops *ops)
  64{
  65        if (ops)
  66                module_put(ops->owner);
  67}
  68
  69static void flush_route_cache(struct fib_rules_ops *ops)
  70{
  71        if (ops->flush_cache)
  72                ops->flush_cache(ops);
  73}
  74
  75int fib_rules_register(struct fib_rules_ops *ops)
  76{
  77        int err = -EEXIST;
  78        struct fib_rules_ops *o;
  79        struct net *net;
  80
  81        net = ops->fro_net;
  82
  83        if (ops->rule_size < sizeof(struct fib_rule))
  84                return -EINVAL;
  85
  86        if (ops->match == NULL || ops->configure == NULL ||
  87            ops->compare == NULL || ops->fill == NULL ||
  88            ops->action == NULL)
  89                return -EINVAL;
  90
  91        spin_lock(&net->rules_mod_lock);
  92        list_for_each_entry(o, &net->rules_ops, list)
  93                if (ops->family == o->family)
  94                        goto errout;
  95
  96        hold_net(net);
  97        list_add_tail_rcu(&ops->list, &net->rules_ops);
  98        err = 0;
  99errout:
 100        spin_unlock(&net->rules_mod_lock);
 101
 102        return err;
 103}
 104
 105EXPORT_SYMBOL_GPL(fib_rules_register);
 106
 107void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
 108{
 109        struct fib_rule *rule, *tmp;
 110
 111        list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
 112                list_del_rcu(&rule->list);
 113                fib_rule_put(rule);
 114        }
 115}
 116EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);
 117
 118void fib_rules_unregister(struct fib_rules_ops *ops)
 119{
 120        struct net *net = ops->fro_net;
 121
 122        spin_lock(&net->rules_mod_lock);
 123        list_del_rcu(&ops->list);
 124        fib_rules_cleanup_ops(ops);
 125        spin_unlock(&net->rules_mod_lock);
 126
 127        synchronize_rcu();
 128        release_net(net);
 129}
 130
 131EXPORT_SYMBOL_GPL(fib_rules_unregister);
 132
 133static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 134                          struct flowi *fl, int flags)
 135{
 136        int ret = 0;
 137
 138        if (rule->ifindex && (rule->ifindex != fl->iif))
 139                goto out;
 140
 141        if ((rule->mark ^ fl->mark) & rule->mark_mask)
 142                goto out;
 143
 144        ret = ops->match(rule, fl, flags);
 145out:
 146        return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
 147}
 148
 149int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 150                     int flags, struct fib_lookup_arg *arg)
 151{
 152        struct fib_rule *rule;
 153        int err;
 154
 155        rcu_read_lock();
 156
 157        list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 158jumped:
 159                if (!fib_rule_match(rule, ops, fl, flags))
 160                        continue;
 161
 162                if (rule->action == FR_ACT_GOTO) {
 163                        struct fib_rule *target;
 164
 165                        target = rcu_dereference(rule->ctarget);
 166                        if (target == NULL) {
 167                                continue;
 168                        } else {
 169                                rule = target;
 170                                goto jumped;
 171                        }
 172                } else if (rule->action == FR_ACT_NOP)
 173                        continue;
 174                else
 175                        err = ops->action(rule, fl, flags, arg);
 176
 177                if (err != -EAGAIN) {
 178                        fib_rule_get(rule);
 179                        arg->rule = rule;
 180                        goto out;
 181                }
 182        }
 183
 184        err = -ESRCH;
 185out:
 186        rcu_read_unlock();
 187
 188        return err;
 189}
 190
 191EXPORT_SYMBOL_GPL(fib_rules_lookup);
 192
 193static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 194                            struct fib_rules_ops *ops)
 195{
 196        int err = -EINVAL;
 197
 198        if (frh->src_len)
 199                if (tb[FRA_SRC] == NULL ||
 200                    frh->src_len > (ops->addr_size * 8) ||
 201                    nla_len(tb[FRA_SRC]) != ops->addr_size)
 202                        goto errout;
 203
 204        if (frh->dst_len)
 205                if (tb[FRA_DST] == NULL ||
 206                    frh->dst_len > (ops->addr_size * 8) ||
 207                    nla_len(tb[FRA_DST]) != ops->addr_size)
 208                        goto errout;
 209
 210        err = 0;
 211errout:
 212        return err;
 213}
 214
 215static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 216{
 217        struct net *net = sock_net(skb->sk);
 218        struct fib_rule_hdr *frh = nlmsg_data(nlh);
 219        struct fib_rules_ops *ops = NULL;
 220        struct fib_rule *rule, *r, *last = NULL;
 221        struct nlattr *tb[FRA_MAX+1];
 222        int err = -EINVAL, unresolved = 0;
 223
 224        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 225                goto errout;
 226
 227        ops = lookup_rules_ops(net, frh->family);
 228        if (ops == NULL) {
 229                err = -EAFNOSUPPORT;
 230                goto errout;
 231        }
 232
 233        err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 234        if (err < 0)
 235                goto errout;
 236
 237        err = validate_rulemsg(frh, tb, ops);
 238        if (err < 0)
 239                goto errout;
 240
 241        rule = kzalloc(ops->rule_size, GFP_KERNEL);
 242        if (rule == NULL) {
 243                err = -ENOMEM;
 244                goto errout;
 245        }
 246        rule->fr_net = hold_net(net);
 247
 248        if (tb[FRA_PRIORITY])
 249                rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 250
 251        if (tb[FRA_IFNAME]) {
 252                struct net_device *dev;
 253
 254                rule->ifindex = -1;
 255                nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 256                dev = __dev_get_by_name(net, rule->ifname);
 257                if (dev)
 258                        rule->ifindex = dev->ifindex;
 259        }
 260
 261        if (tb[FRA_FWMARK]) {
 262                rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 263                if (rule->mark)
 264                        /* compatibility: if the mark value is non-zero all bits
 265                         * are compared unless a mask is explicitly specified.
 266                         */
 267                        rule->mark_mask = 0xFFFFFFFF;
 268        }
 269
 270        if (tb[FRA_FWMASK])
 271                rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 272
 273        rule->action = frh->action;
 274        rule->flags = frh->flags;
 275        rule->table = frh_get_table(frh, tb);
 276
 277        if (!rule->pref && ops->default_pref)
 278                rule->pref = ops->default_pref(ops);
 279
 280        err = -EINVAL;
 281        if (tb[FRA_GOTO]) {
 282                if (rule->action != FR_ACT_GOTO)
 283                        goto errout_free;
 284
 285                rule->target = nla_get_u32(tb[FRA_GOTO]);
 286                /* Backward jumps are prohibited to avoid endless loops */
 287                if (rule->target <= rule->pref)
 288                        goto errout_free;
 289
 290                list_for_each_entry(r, &ops->rules_list, list) {
 291                        if (r->pref == rule->target) {
 292                                rule->ctarget = r;
 293                                break;
 294                        }
 295                }
 296
 297                if (rule->ctarget == NULL)
 298                        unresolved = 1;
 299        } else if (rule->action == FR_ACT_GOTO)
 300                goto errout_free;
 301
 302        err = ops->configure(rule, skb, nlh, frh, tb);
 303        if (err < 0)
 304                goto errout_free;
 305
 306        list_for_each_entry(r, &ops->rules_list, list) {
 307                if (r->pref > rule->pref)
 308                        break;
 309                last = r;
 310        }
 311
 312        fib_rule_get(rule);
 313
 314        if (ops->unresolved_rules) {
 315                /*
 316                 * There are unresolved goto rules in the list, check if
 317                 * any of them are pointing to this new rule.
 318                 */
 319                list_for_each_entry(r, &ops->rules_list, list) {
 320                        if (r->action == FR_ACT_GOTO &&
 321                            r->target == rule->pref) {
 322                                BUG_ON(r->ctarget != NULL);
 323                                rcu_assign_pointer(r->ctarget, rule);
 324                                if (--ops->unresolved_rules == 0)
 325                                        break;
 326                        }
 327                }
 328        }
 329
 330        if (rule->action == FR_ACT_GOTO)
 331                ops->nr_goto_rules++;
 332
 333        if (unresolved)
 334                ops->unresolved_rules++;
 335
 336        if (last)
 337                list_add_rcu(&rule->list, &last->list);
 338        else
 339                list_add_rcu(&rule->list, &ops->rules_list);
 340
 341        notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 342        flush_route_cache(ops);
 343        rules_ops_put(ops);
 344        return 0;
 345
 346errout_free:
 347        release_net(rule->fr_net);
 348        kfree(rule);
 349errout:
 350        rules_ops_put(ops);
 351        return err;
 352}
 353
 354static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 355{
 356        struct net *net = sock_net(skb->sk);
 357        struct fib_rule_hdr *frh = nlmsg_data(nlh);
 358        struct fib_rules_ops *ops = NULL;
 359        struct fib_rule *rule, *tmp;
 360        struct nlattr *tb[FRA_MAX+1];
 361        int err = -EINVAL;
 362
 363        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 364                goto errout;
 365
 366        ops = lookup_rules_ops(net, frh->family);
 367        if (ops == NULL) {
 368                err = -EAFNOSUPPORT;
 369                goto errout;
 370        }
 371
 372        err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 373        if (err < 0)
 374                goto errout;
 375
 376        err = validate_rulemsg(frh, tb, ops);
 377        if (err < 0)
 378                goto errout;
 379
 380        list_for_each_entry(rule, &ops->rules_list, list) {
 381                if (frh->action && (frh->action != rule->action))
 382                        continue;
 383
 384                if (frh->table && (frh_get_table(frh, tb) != rule->table))
 385                        continue;
 386
 387                if (tb[FRA_PRIORITY] &&
 388                    (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 389                        continue;
 390
 391                if (tb[FRA_IFNAME] &&
 392                    nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 393                        continue;
 394
 395                if (tb[FRA_FWMARK] &&
 396                    (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 397                        continue;
 398
 399                if (tb[FRA_FWMASK] &&
 400                    (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 401                        continue;
 402
 403                if (!ops->compare(rule, frh, tb))
 404                        continue;
 405
 406                if (rule->flags & FIB_RULE_PERMANENT) {
 407                        err = -EPERM;
 408                        goto errout;
 409                }
 410
 411                list_del_rcu(&rule->list);
 412
 413                if (rule->action == FR_ACT_GOTO)
 414                        ops->nr_goto_rules--;
 415
 416                /*
 417                 * Check if this rule is a target to any of them. If so,
 418                 * disable them. As this operation is eventually very
 419                 * expensive, it is only performed if goto rules have
 420                 * actually been added.
 421                 */
 422                if (ops->nr_goto_rules > 0) {
 423                        list_for_each_entry(tmp, &ops->rules_list, list) {
 424                                if (tmp->ctarget == rule) {
 425                                        rcu_assign_pointer(tmp->ctarget, NULL);
 426                                        ops->unresolved_rules++;
 427                                }
 428                        }
 429                }
 430
 431                synchronize_rcu();
 432                notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 433                                   NETLINK_CB(skb).pid);
 434                fib_rule_put(rule);
 435                flush_route_cache(ops);
 436                rules_ops_put(ops);
 437                return 0;
 438        }
 439
 440        err = -ENOENT;
 441errout:
 442        rules_ops_put(ops);
 443        return err;
 444}
 445
 446static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 447                                         struct fib_rule *rule)
 448{
 449        size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 450                         + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
 451                         + nla_total_size(4) /* FRA_PRIORITY */
 452                         + nla_total_size(4) /* FRA_TABLE */
 453                         + nla_total_size(4) /* FRA_FWMARK */
 454                         + nla_total_size(4); /* FRA_FWMASK */
 455
 456        if (ops->nlmsg_payload)
 457                payload += ops->nlmsg_payload(rule);
 458
 459        return payload;
 460}
 461
 462static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 463                            u32 pid, u32 seq, int type, int flags,
 464                            struct fib_rules_ops *ops)
 465{
 466        struct nlmsghdr *nlh;
 467        struct fib_rule_hdr *frh;
 468
 469        nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 470        if (nlh == NULL)
 471                return -EMSGSIZE;
 472
 473        frh = nlmsg_data(nlh);
 474        frh->table = rule->table;
 475        NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 476        frh->res1 = 0;
 477        frh->res2 = 0;
 478        frh->action = rule->action;
 479        frh->flags = rule->flags;
 480
 481        if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
 482                frh->flags |= FIB_RULE_UNRESOLVED;
 483
 484        if (rule->ifname[0]) {
 485                NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 486
 487                if (rule->ifindex == -1)
 488                        frh->flags |= FIB_RULE_DEV_DETACHED;
 489        }
 490
 491        if (rule->pref)
 492                NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 493
 494        if (rule->mark)
 495                NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 496
 497        if (rule->mark_mask || rule->mark)
 498                NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 499
 500        if (rule->target)
 501                NLA_PUT_U32(skb, FRA_GOTO, rule->target);
 502
 503        if (ops->fill(rule, skb, nlh, frh) < 0)
 504                goto nla_put_failure;
 505
 506        return nlmsg_end(skb, nlh);
 507
 508nla_put_failure:
 509        nlmsg_cancel(skb, nlh);
 510        return -EMSGSIZE;
 511}
 512
 513static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
 514                      struct fib_rules_ops *ops)
 515{
 516        int idx = 0;
 517        struct fib_rule *rule;
 518
 519        list_for_each_entry(rule, &ops->rules_list, list) {
 520                if (idx < cb->args[1])
 521                        goto skip;
 522
 523                if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 524                                     cb->nlh->nlmsg_seq, RTM_NEWRULE,
 525                                     NLM_F_MULTI, ops) < 0)
 526                        break;
 527skip:
 528                idx++;
 529        }
 530        cb->args[1] = idx;
 531        rules_ops_put(ops);
 532
 533        return skb->len;
 534}
 535
 536static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
 537{
 538        struct net *net = sock_net(skb->sk);
 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(net, 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, &net->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
 570static 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 net *net;
 575        struct sk_buff *skb;
 576        int err = -ENOBUFS;
 577
 578        net = ops->fro_net;
 579        skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 580        if (skb == NULL)
 581                goto errout;
 582
 583        err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 584        if (err < 0) {
 585                /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
 586                WARN_ON(err == -EMSGSIZE);
 587                kfree_skb(skb);
 588                goto errout;
 589        }
 590
 591        rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
 592        return;
 593errout:
 594        if (err < 0)
 595                rtnl_set_sk_err(net, ops->nlgroup, err);
 596}
 597
 598static void attach_rules(struct list_head *rules, struct net_device *dev)
 599{
 600        struct fib_rule *rule;
 601
 602        list_for_each_entry(rule, rules, list) {
 603                if (rule->ifindex == -1 &&
 604                    strcmp(dev->name, rule->ifname) == 0)
 605                        rule->ifindex = dev->ifindex;
 606        }
 607}
 608
 609static void detach_rules(struct list_head *rules, struct net_device *dev)
 610{
 611        struct fib_rule *rule;
 612
 613        list_for_each_entry(rule, rules, list)
 614                if (rule->ifindex == dev->ifindex)
 615                        rule->ifindex = -1;
 616}
 617
 618
 619static int fib_rules_event(struct notifier_block *this, unsigned long event,
 620                            void *ptr)
 621{
 622        struct net_device *dev = ptr;
 623        struct net *net = dev_net(dev);
 624        struct fib_rules_ops *ops;
 625
 626        ASSERT_RTNL();
 627        rcu_read_lock();
 628
 629        switch (event) {
 630        case NETDEV_REGISTER:
 631                list_for_each_entry(ops, &net->rules_ops, list)
 632                        attach_rules(&ops->rules_list, dev);
 633                break;
 634
 635        case NETDEV_UNREGISTER:
 636                list_for_each_entry(ops, &net->rules_ops, list)
 637                        detach_rules(&ops->rules_list, dev);
 638                break;
 639        }
 640
 641        rcu_read_unlock();
 642
 643        return NOTIFY_DONE;
 644}
 645
 646static struct notifier_block fib_rules_notifier = {
 647        .notifier_call = fib_rules_event,
 648};
 649
 650static int fib_rules_net_init(struct net *net)
 651{
 652        INIT_LIST_HEAD(&net->rules_ops);
 653        spin_lock_init(&net->rules_mod_lock);
 654        return 0;
 655}
 656
 657static struct pernet_operations fib_rules_net_ops = {
 658        .init = fib_rules_net_init,
 659};
 660
 661static int __init fib_rules_init(void)
 662{
 663        int err;
 664        rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
 665        rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
 666        rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
 667
 668        err = register_pernet_subsys(&fib_rules_net_ops);
 669        if (err < 0)
 670                goto fail;
 671
 672        err = register_netdevice_notifier(&fib_rules_notifier);
 673        if (err < 0)
 674                goto fail_unregister;
 675
 676        return 0;
 677
 678fail_unregister:
 679        unregister_pernet_subsys(&fib_rules_net_ops);
 680fail:
 681        rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
 682        rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
 683        rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
 684        return err;
 685}
 686
 687subsys_initcall(fib_rules_init);
 688