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 static void notify_rule_change(int event, struct fib_rule *rule,
  20                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
  21                                u32 pid);
  22
  23 static struct fib_rules_ops *lookup_rules_ops(int family)
  24 {
  25         struct fib_rules_ops *ops;
  26
  27         rcu_read_lock();
  28         list_for_each_entry_rcu(ops, &rules_ops, list) {
  29                 if (ops->family == family) {
  30                         if (!try_module_get(ops->owner))
  31                                 ops = NULL;
  32                         rcu_read_unlock();
  33                         return ops;
  34                 }
  35         }
  36         rcu_read_unlock();
  37
  38         return NULL;
  39 }
  40
  41 static void rules_ops_put(struct fib_rules_ops *ops)
  42 {
  43         if (ops)
  44                 module_put(ops->owner);
  45 }
  46
  47 int fib_rules_register(struct fib_rules_ops *ops)
  48 {
  49         int err = -EEXIST;
  50         struct fib_rules_ops *o;
  51
  52         if (ops->rule_size < sizeof(struct fib_rule))
  53                 return -EINVAL;
  54
  55         if (ops->match == NULL || ops->configure == NULL ||
  56             ops->compare == NULL || ops->fill == NULL ||
  57             ops->action == NULL)
  58                 return -EINVAL;
  59
  60         spin_lock(&rules_mod_lock);
  61         list_for_each_entry(o, &rules_ops, list)
  62                 if (ops->family == o->family)
  63                         goto errout;
  64
  65         list_add_tail_rcu(&ops->list, &rules_ops);
  66         err = 0;
  67 errout:
  68         spin_unlock(&rules_mod_lock);
  69
  70         return err;
  71 }
  72
  73 EXPORT_SYMBOL_GPL(fib_rules_register);
  74
  75 static void cleanup_ops(struct fib_rules_ops *ops)
  76 {
  77         struct fib_rule *rule, *tmp;
  78
  79         list_for_each_entry_safe(rule, tmp, ops->rules_list, list) {
  80                 list_del_rcu(&rule->list);
  81                 fib_rule_put(rule);
  82         }
  83 }
  84
  85 int fib_rules_unregister(struct fib_rules_ops *ops)
  86 {
  87         int err = 0;
  88         struct fib_rules_ops *o;
  89
  90         spin_lock(&rules_mod_lock);
  91         list_for_each_entry(o, &rules_ops, list) {
  92                 if (o == ops) {
  93                         list_del_rcu(&o->list);
  94                         cleanup_ops(ops);
  95                         goto out;
  96                 }
  97         }
  98
  99         err = -ENOENT;
 100 out:
 101         spin_unlock(&rules_mod_lock);
 102
 103         synchronize_rcu();
 104
 105         return err;
 106 }
 107
 108 EXPORT_SYMBOL_GPL(fib_rules_unregister);
 109
 110 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 111                           struct flowi *fl, int flags)
 112 {
 113         int ret = 0;
 114
 115         if (rule->ifindex && (rule->ifindex != fl->iif))
 116                 goto out;
 117
 118         if ((rule->mark ^ fl->mark) & rule->mark_mask)
 119                 goto out;
 120
 121         ret = ops->match(rule, fl, flags);
 122 out:
 123         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
 124 }
 125
 126 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 127                      int flags, struct fib_lookup_arg *arg)
 128 {
 129         struct fib_rule *rule;
 130         int err;
 131
 132         rcu_read_lock();
 133
 134         list_for_each_entry_rcu(rule, ops->rules_list, list) {
 135                 if (!fib_rule_match(rule, ops, fl, flags))
 136                         continue;
 137
 138                 err = ops->action(rule, fl, flags, arg);
 139                 if (err != -EAGAIN) {
 140                         fib_rule_get(rule);
 141                         arg->rule = rule;
 142                         goto out;
 143                 }
 144         }
 145
 146         err = -ENETUNREACH;
 147 out:
 148         rcu_read_unlock();
 149
 150         return err;
 151 }
 152
 153 EXPORT_SYMBOL_GPL(fib_rules_lookup);
 154
 155 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 156                             struct fib_rules_ops *ops)
 157 {
 158         int err = -EINVAL;
 159
 160         if (frh->src_len)
 161                 if (tb[FRA_SRC] == NULL ||
 162                     frh->src_len > (ops->addr_size * 8) ||
 163                     nla_len(tb[FRA_SRC]) != ops->addr_size)
 164                         goto errout;
 165
 166         if (frh->dst_len)
 167                 if (tb[FRA_DST] == NULL ||
 168                     frh->dst_len > (ops->addr_size * 8) ||
 169                     nla_len(tb[FRA_DST]) != ops->addr_size)
 170                         goto errout;
 171
 172         err = 0;
 173 errout:
 174         return err;
 175 }
 176
 177 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 178 {
 179         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 180         struct fib_rules_ops *ops = NULL;
 181         struct fib_rule *rule, *r, *last = NULL;
 182         struct nlattr *tb[FRA_MAX+1];
 183         int err = -EINVAL;
 184
 185         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 186                 goto errout;
 187
 188         ops = lookup_rules_ops(frh->family);
 189         if (ops == NULL) {
 190                 err = EAFNOSUPPORT;
 191                 goto errout;
 192         }
 193
 194         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 195         if (err < 0)
 196                 goto errout;
 197
 198         err = validate_rulemsg(frh, tb, ops);
 199         if (err < 0)
 200                 goto errout;
 201
 202         rule = kzalloc(ops->rule_size, GFP_KERNEL);
 203         if (rule == NULL) {
 204                 err = -ENOMEM;
 205                 goto errout;
 206         }
 207
 208         if (tb[FRA_PRIORITY])
 209                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 210
 211         if (tb[FRA_IFNAME]) {
 212                 struct net_device *dev;
 213
 214                 rule->ifindex = -1;
 215                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 216                 dev = __dev_get_by_name(rule->ifname);
 217                 if (dev)
 218                         rule->ifindex = dev->ifindex;
 219         }
 220
 221         if (tb[FRA_FWMARK]) {
 222                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 223                 if (rule->mark)
 224                         /* compatibility: if the mark value is non-zero all bits
 225                          * are compared unless a mask is explicitly specified.
 226                          */
 227                         rule->mark_mask = 0xFFFFFFFF;
 228         }
 229
 230         if (tb[FRA_FWMASK])
 231                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 232
 233         rule->action = frh->action;
 234         rule->flags = frh->flags;
 235         rule->table = frh_get_table(frh, tb);
 236
 237         if (!rule->pref && ops->default_pref)
 238                 rule->pref = ops->default_pref();
 239
 240         err = ops->configure(rule, skb, nlh, frh, tb);
 241         if (err < 0)
 242                 goto errout_free;
 243
 244         list_for_each_entry(r, ops->rules_list, list) {
 245                 if (r->pref > rule->pref)
 246                         break;
 247                 last = r;
 248         }
 249
 250         fib_rule_get(rule);
 251
 252         if (last)
 253                 list_add_rcu(&rule->list, &last->list);
 254         else
 255                 list_add_rcu(&rule->list, ops->rules_list);
 256
 257         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 258         rules_ops_put(ops);
 259         return 0;
 260
 261 errout_free:
 262         kfree(rule);
 263 errout:
 264         rules_ops_put(ops);
 265         return err;
 266 }
 267
 268 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 269 {
 270         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 271         struct fib_rules_ops *ops = NULL;
 272         struct fib_rule *rule;
 273         struct nlattr *tb[FRA_MAX+1];
 274         int err = -EINVAL;
 275
 276         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 277                 goto errout;
 278
 279         ops = lookup_rules_ops(frh->family);
 280         if (ops == NULL) {
 281                 err = EAFNOSUPPORT;
 282                 goto errout;
 283         }
 284
 285         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 286         if (err < 0)
 287                 goto errout;
 288
 289         err = validate_rulemsg(frh, tb, ops);
 290         if (err < 0)
 291                 goto errout;
 292
 293         list_for_each_entry(rule, ops->rules_list, list) {
 294                 if (frh->action && (frh->action != rule->action))
 295                         continue;
 296
 297                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
 298                         continue;
 299
 300                 if (tb[FRA_PRIORITY] &&
 301                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 302                         continue;
 303
 304                 if (tb[FRA_IFNAME] &&
 305                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 306                         continue;
 307
 308                 if (tb[FRA_FWMARK] &&
 309                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 310                         continue;
 311
 312                 if (tb[FRA_FWMASK] &&
 313                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 314                         continue;
 315
 316                 if (!ops->compare(rule, frh, tb))
 317                         continue;
 318
 319                 if (rule->flags & FIB_RULE_PERMANENT) {
 320                         err = -EPERM;
 321                         goto errout;
 322                 }
 323
 324                 list_del_rcu(&rule->list);
 325                 synchronize_rcu();
 326                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 327                                    NETLINK_CB(skb).pid);
 328                 fib_rule_put(rule);
 329                 rules_ops_put(ops);
 330                 return 0;
 331         }
 332
 333         err = -ENOENT;
 334 errout:
 335         rules_ops_put(ops);
 336         return err;
 337 }
 338
 339 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 340                                          struct fib_rule *rule)
 341 {
 342         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 343                          + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
 344                          + nla_total_size(4) /* FRA_PRIORITY */
 345                          + nla_total_size(4) /* FRA_TABLE */
 346                          + nla_total_size(4) /* FRA_FWMARK */
 347                          + nla_total_size(4); /* FRA_FWMASK */
 348
 349         if (ops->nlmsg_payload)
 350                 payload += ops->nlmsg_payload(rule);
 351
 352         return payload;
 353 }
 354
 355 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 356                             u32 pid, u32 seq, int type, int flags,
 357                             struct fib_rules_ops *ops)
 358 {
 359         struct nlmsghdr *nlh;
 360         struct fib_rule_hdr *frh;
 361
 362         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 363         if (nlh == NULL)
 364                 return -1;
 365
 366         frh = nlmsg_data(nlh);
 367         frh->table = rule->table;
 368         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 369         frh->res1 = 0;
 370         frh->res2 = 0;
 371         frh->action = rule->action;
 372         frh->flags = rule->flags;
 373
 374         if (rule->ifname[0])
 375                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 376
 377         if (rule->pref)
 378                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 379
 380         if (rule->mark)
 381                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 382
 383         if (rule->mark_mask || rule->mark)
 384                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 385
 386         if (ops->fill(rule, skb, nlh, frh) < 0)
 387                 goto nla_put_failure;
 388
 389         return nlmsg_end(skb, nlh);
 390
 391 nla_put_failure:
 392         return nlmsg_cancel(skb, nlh);
 393 }
 394
 395 int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
 396 {
 397         int idx = 0;
 398         struct fib_rule *rule;
 399         struct fib_rules_ops *ops;
 400
 401         ops = lookup_rules_ops(family);
 402         if (ops == NULL)
 403                 return -EAFNOSUPPORT;
 404
 405         rcu_read_lock();
 406         list_for_each_entry(rule, ops->rules_list, list) {
 407                 if (idx < cb->args[0])
 408                         goto skip;
 409
 410                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 411                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 412                                      NLM_F_MULTI, ops) < 0)
 413                         break;
 414 skip:
 415                 idx++;
 416         }
 417         rcu_read_unlock();
 418         cb->args[0] = idx;
 419         rules_ops_put(ops);
 420
 421         return skb->len;
 422 }
 423
 424 EXPORT_SYMBOL_GPL(fib_rules_dump);
 425
 426 static void notify_rule_change(int event, struct fib_rule *rule,
 427                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 428                                u32 pid)
 429 {
 430         struct sk_buff *skb;
 431         int err = -ENOBUFS;
 432
 433         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 434         if (skb == NULL)
 435                 goto errout;
 436
 437         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 438         /* failure implies BUG in fib_rule_nlmsg_size() */
 439         BUG_ON(err < 0);
 440
 441         err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
 442 errout:
 443         if (err < 0)
 444                 rtnl_set_sk_err(ops->nlgroup, err);
 445 }
 446
 447 static void attach_rules(struct list_head *rules, struct net_device *dev)
 448 {
 449         struct fib_rule *rule;
 450
 451         list_for_each_entry(rule, rules, list) {
 452                 if (rule->ifindex == -1 &&
 453                     strcmp(dev->name, rule->ifname) == 0)
 454                         rule->ifindex = dev->ifindex;
 455         }
 456 }
 457
 458 static void detach_rules(struct list_head *rules, struct net_device *dev)
 459 {
 460         struct fib_rule *rule;
 461
 462         list_for_each_entry(rule, rules, list)
 463                 if (rule->ifindex == dev->ifindex)
 464                         rule->ifindex = -1;
 465 }
 466
 467
 468 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 469                             void *ptr)
 470 {
 471         struct net_device *dev = ptr;
 472         struct fib_rules_ops *ops;
 473
 474         ASSERT_RTNL();
 475         rcu_read_lock();
 476
 477         switch (event) {
 478         case NETDEV_REGISTER:
 479                 list_for_each_entry(ops, &rules_ops, list)
 480                         attach_rules(ops->rules_list, dev);
 481                 break;
 482
 483         case NETDEV_UNREGISTER:
 484                 list_for_each_entry(ops, &rules_ops, list)
 485                         detach_rules(ops->rules_list, dev);
 486                 break;
 487         }
 488
 489         rcu_read_unlock();
 490
 491         return NOTIFY_DONE;
 492 }
 493
 494 static struct notifier_block fib_rules_notifier = {
 495         .notifier_call = fib_rules_event,
 496 };
 497
 498 static int __init fib_rules_init(void)
 499 {
 500         return register_netdevice_notifier(&fib_rules_notifier);
 501 }
 502
 503 subsys_initcall(fib_rules_init);