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 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 156 {
 157         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 158         struct fib_rules_ops *ops = NULL;
 159         struct fib_rule *rule, *r, *last = NULL;
 160         struct nlattr *tb[FRA_MAX+1];
 161         int err = -EINVAL;
 162
 163         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 164                 goto errout;
 165
 166         ops = lookup_rules_ops(frh->family);
 167         if (ops == NULL) {
 168                 err = EAFNOSUPPORT;
 169                 goto errout;
 170         }
 171
 172         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 173         if (err < 0)
 174                 goto errout;
 175
 176         rule = kzalloc(ops->rule_size, GFP_KERNEL);
 177         if (rule == NULL) {
 178                 err = -ENOMEM;
 179                 goto errout;
 180         }
 181
 182         if (tb[FRA_PRIORITY])
 183                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 184
 185         if (tb[FRA_IFNAME]) {
 186                 struct net_device *dev;
 187
 188                 rule->ifindex = -1;
 189                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 190                 dev = __dev_get_by_name(rule->ifname);
 191                 if (dev)
 192                         rule->ifindex = dev->ifindex;
 193         }
 194
 195         if (tb[FRA_FWMARK]) {
 196                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 197                 if (rule->mark)
 198                         /* compatibility: if the mark value is non-zero all bits
 199                          * are compared unless a mask is explicitly specified.
 200                          */
 201                         rule->mark_mask = 0xFFFFFFFF;
 202         }
 203
 204         if (tb[FRA_FWMASK])
 205                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 206
 207         rule->action = frh->action;
 208         rule->flags = frh->flags;
 209         rule->table = frh_get_table(frh, tb);
 210
 211         if (!rule->pref && ops->default_pref)
 212                 rule->pref = ops->default_pref();
 213
 214         err = ops->configure(rule, skb, nlh, frh, tb);
 215         if (err < 0)
 216                 goto errout_free;
 217
 218         list_for_each_entry(r, ops->rules_list, list) {
 219                 if (r->pref > rule->pref)
 220                         break;
 221                 last = r;
 222         }
 223
 224         fib_rule_get(rule);
 225
 226         if (last)
 227                 list_add_rcu(&rule->list, &last->list);
 228         else
 229                 list_add_rcu(&rule->list, ops->rules_list);
 230
 231         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 232         rules_ops_put(ops);
 233         return 0;
 234
 235 errout_free:
 236         kfree(rule);
 237 errout:
 238         rules_ops_put(ops);
 239         return err;
 240 }
 241
 242 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 243 {
 244         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 245         struct fib_rules_ops *ops = NULL;
 246         struct fib_rule *rule;
 247         struct nlattr *tb[FRA_MAX+1];
 248         int err = -EINVAL;
 249
 250         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 251                 goto errout;
 252
 253         ops = lookup_rules_ops(frh->family);
 254         if (ops == NULL) {
 255                 err = EAFNOSUPPORT;
 256                 goto errout;
 257         }
 258
 259         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 260         if (err < 0)
 261                 goto errout;
 262
 263         list_for_each_entry(rule, ops->rules_list, list) {
 264                 if (frh->action && (frh->action != rule->action))
 265                         continue;
 266
 267                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
 268                         continue;
 269
 270                 if (tb[FRA_PRIORITY] &&
 271                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 272                         continue;
 273
 274                 if (tb[FRA_IFNAME] &&
 275                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 276                         continue;
 277
 278                 if (tb[FRA_FWMARK] &&
 279                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 280                         continue;
 281
 282                 if (tb[FRA_FWMASK] &&
 283                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 284                         continue;
 285
 286                 if (!ops->compare(rule, frh, tb))
 287                         continue;
 288
 289                 if (rule->flags & FIB_RULE_PERMANENT) {
 290                         err = -EPERM;
 291                         goto errout;
 292                 }
 293
 294                 list_del_rcu(&rule->list);
 295                 synchronize_rcu();
 296                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 297                                    NETLINK_CB(skb).pid);
 298                 fib_rule_put(rule);
 299                 rules_ops_put(ops);
 300                 return 0;
 301         }
 302
 303         err = -ENOENT;
 304 errout:
 305         rules_ops_put(ops);
 306         return err;
 307 }
 308
 309 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 310                                          struct fib_rule *rule)
 311 {
 312         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 313                          + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
 314                          + nla_total_size(4) /* FRA_PRIORITY */
 315                          + nla_total_size(4) /* FRA_TABLE */
 316                          + nla_total_size(4) /* FRA_FWMARK */
 317                          + nla_total_size(4); /* FRA_FWMASK */
 318
 319         if (ops->nlmsg_payload)
 320                 payload += ops->nlmsg_payload(rule);
 321
 322         return payload;
 323 }
 324
 325 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 326                             u32 pid, u32 seq, int type, int flags,
 327                             struct fib_rules_ops *ops)
 328 {
 329         struct nlmsghdr *nlh;
 330         struct fib_rule_hdr *frh;
 331
 332         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 333         if (nlh == NULL)
 334                 return -EMSGSIZE;
 335
 336         frh = nlmsg_data(nlh);
 337         frh->table = rule->table;
 338         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 339         frh->res1 = 0;
 340         frh->res2 = 0;
 341         frh->action = rule->action;
 342         frh->flags = rule->flags;
 343
 344         if (rule->ifname[0])
 345                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 346
 347         if (rule->pref)
 348                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 349
 350         if (rule->mark)
 351                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 352
 353         if (rule->mark_mask || rule->mark)
 354                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 355
 356         if (ops->fill(rule, skb, nlh, frh) < 0)
 357                 goto nla_put_failure;
 358
 359         return nlmsg_end(skb, nlh);
 360
 361 nla_put_failure:
 362         nlmsg_cancel(skb, nlh);
 363         return -EMSGSIZE;
 364 }
 365
 366 int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
 367 {
 368         int idx = 0;
 369         struct fib_rule *rule;
 370         struct fib_rules_ops *ops;
 371
 372         ops = lookup_rules_ops(family);
 373         if (ops == NULL)
 374                 return -EAFNOSUPPORT;
 375
 376         rcu_read_lock();
 377         list_for_each_entry(rule, ops->rules_list, list) {
 378                 if (idx < cb->args[0])
 379                         goto skip;
 380
 381                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 382                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 383                                      NLM_F_MULTI, ops) < 0)
 384                         break;
 385 skip:
 386                 idx++;
 387         }
 388         rcu_read_unlock();
 389         cb->args[0] = idx;
 390         rules_ops_put(ops);
 391
 392         return skb->len;
 393 }
 394
 395 EXPORT_SYMBOL_GPL(fib_rules_dump);
 396
 397 static void notify_rule_change(int event, struct fib_rule *rule,
 398                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 399                                u32 pid)
 400 {
 401         struct sk_buff *skb;
 402         int err = -ENOBUFS;
 403
 404         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 405         if (skb == NULL)
 406                 goto errout;
 407
 408         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 409         if (err < 0) {
 410                 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
 411                 WARN_ON(err == -EMSGSIZE);
 412                 kfree_skb(skb);
 413                 goto errout;
 414         }
 415         err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
 416 errout:
 417         if (err < 0)
 418                 rtnl_set_sk_err(ops->nlgroup, err);
 419 }
 420
 421 static void attach_rules(struct list_head *rules, struct net_device *dev)
 422 {
 423         struct fib_rule *rule;
 424
 425         list_for_each_entry(rule, rules, list) {
 426                 if (rule->ifindex == -1 &&
 427                     strcmp(dev->name, rule->ifname) == 0)
 428                         rule->ifindex = dev->ifindex;
 429         }
 430 }
 431
 432 static void detach_rules(struct list_head *rules, struct net_device *dev)
 433 {
 434         struct fib_rule *rule;
 435
 436         list_for_each_entry(rule, rules, list)
 437                 if (rule->ifindex == dev->ifindex)
 438                         rule->ifindex = -1;
 439 }
 440
 441
 442 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 443                             void *ptr)
 444 {
 445         struct net_device *dev = ptr;
 446         struct fib_rules_ops *ops;
 447
 448         ASSERT_RTNL();
 449         rcu_read_lock();
 450
 451         switch (event) {
 452         case NETDEV_REGISTER:
 453                 list_for_each_entry(ops, &rules_ops, list)
 454                         attach_rules(ops->rules_list, dev);
 455                 break;
 456
 457         case NETDEV_UNREGISTER:
 458                 list_for_each_entry(ops, &rules_ops, list)
 459                         detach_rules(ops->rules_list, dev);
 460                 break;
 461         }
 462
 463         rcu_read_unlock();
 464
 465         return NOTIFY_DONE;
 466 }
 467
 468 static struct notifier_block fib_rules_notifier = {
 469         .notifier_call = fib_rules_event,
 470 };
 471
 472 static int __init fib_rules_init(void)
 473 {
 474         return register_netdevice_notifier(&fib_rules_notifier);
 475 }
 476
 477 subsys_initcall(fib_rules_init);