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/config.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/list.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);
  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 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 111                      int flags, struct fib_lookup_arg *arg)
 112 {
 113         struct fib_rule *rule;
 114         int err;
 115
 116         rcu_read_lock();
 117
 118         list_for_each_entry_rcu(rule, ops->rules_list, list) {
 119                 if (rule->ifindex && (rule->ifindex != fl->iif))
 120                         continue;
 121
 122                 if (!ops->match(rule, fl, flags))
 123                         continue;
 124
 125                 err = ops->action(rule, fl, flags, arg);
 126                 if (err != -EAGAIN) {
 127                         fib_rule_get(rule);
 128                         arg->rule = rule;
 129                         goto out;
 130                 }
 131         }
 132
 133         err = -ENETUNREACH;
 134 out:
 135         rcu_read_unlock();
 136
 137         return err;
 138 }
 139
 140 EXPORT_SYMBOL_GPL(fib_rules_lookup);
 141
 142 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 143 {
 144         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 145         struct fib_rules_ops *ops = NULL;
 146         struct fib_rule *rule, *r, *last = NULL;
 147         struct nlattr *tb[FRA_MAX+1];
 148         int err = -EINVAL;
 149
 150         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 151                 goto errout;
 152
 153         ops = lookup_rules_ops(frh->family);
 154         if (ops == NULL) {
 155                 err = EAFNOSUPPORT;
 156                 goto errout;
 157         }
 158
 159         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 160         if (err < 0)
 161                 goto errout;
 162
 163         if (tb[FRA_IFNAME] && nla_len(tb[FRA_IFNAME]) > IFNAMSIZ)
 164                 goto errout;
 165
 166         rule = kzalloc(ops->rule_size, GFP_KERNEL);
 167         if (rule == NULL) {
 168                 err = -ENOMEM;
 169                 goto errout;
 170         }
 171
 172         if (tb[FRA_PRIORITY])
 173                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 174
 175         if (tb[FRA_IFNAME]) {
 176                 struct net_device *dev;
 177
 178                 rule->ifindex = -1;
 179                 if (nla_strlcpy(rule->ifname, tb[FRA_IFNAME],
 180                                 IFNAMSIZ) >= IFNAMSIZ)
 181                         goto errout_free;
 182
 183                 dev = __dev_get_by_name(rule->ifname);
 184                 if (dev)
 185                         rule->ifindex = dev->ifindex;
 186         }
 187
 188         rule->action = frh->action;
 189         rule->flags = frh->flags;
 190         rule->table = frh->table;
 191
 192         if (!rule->pref && ops->default_pref)
 193                 rule->pref = ops->default_pref();
 194
 195         err = ops->configure(rule, skb, nlh, frh, tb);
 196         if (err < 0)
 197                 goto errout_free;
 198
 199         list_for_each_entry(r, ops->rules_list, list) {
 200                 if (r->pref > rule->pref)
 201                         break;
 202                 last = r;
 203         }
 204
 205         fib_rule_get(rule);
 206
 207         if (last)
 208                 list_add_rcu(&rule->list, &last->list);
 209         else
 210                 list_add_rcu(&rule->list, ops->rules_list);
 211
 212         notify_rule_change(RTM_NEWRULE, rule, ops);
 213         rules_ops_put(ops);
 214         return 0;
 215
 216 errout_free:
 217         kfree(rule);
 218 errout:
 219         rules_ops_put(ops);
 220         return err;
 221 }
 222
 223 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 224 {
 225         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 226         struct fib_rules_ops *ops = NULL;
 227         struct fib_rule *rule;
 228         struct nlattr *tb[FRA_MAX+1];
 229         int err = -EINVAL;
 230
 231         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 232                 goto errout;
 233
 234         ops = lookup_rules_ops(frh->family);
 235         if (ops == NULL) {
 236                 err = EAFNOSUPPORT;
 237                 goto errout;
 238         }
 239
 240         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 241         if (err < 0)
 242                 goto errout;
 243
 244         list_for_each_entry(rule, ops->rules_list, list) {
 245                 if (frh->action && (frh->action != rule->action))
 246                         continue;
 247
 248                 if (frh->table && (frh->table != rule->table))
 249                         continue;
 250
 251                 if (tb[FRA_PRIORITY] &&
 252                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 253                         continue;
 254
 255                 if (tb[FRA_IFNAME] &&
 256                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 257                         continue;
 258
 259                 if (!ops->compare(rule, frh, tb))
 260                         continue;
 261
 262                 if (rule->flags & FIB_RULE_PERMANENT) {
 263                         err = -EPERM;
 264                         goto errout;
 265                 }
 266
 267                 list_del_rcu(&rule->list);
 268                 synchronize_rcu();
 269                 notify_rule_change(RTM_DELRULE, rule, ops);
 270                 fib_rule_put(rule);
 271                 rules_ops_put(ops);
 272                 return 0;
 273         }
 274
 275         err = -ENOENT;
 276 errout:
 277         rules_ops_put(ops);
 278         return err;
 279 }
 280
 281 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 282                             u32 pid, u32 seq, int type, int flags,
 283                             struct fib_rules_ops *ops)
 284 {
 285         struct nlmsghdr *nlh;
 286         struct fib_rule_hdr *frh;
 287
 288         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 289         if (nlh == NULL)
 290                 return -1;
 291
 292         frh = nlmsg_data(nlh);
 293         frh->table = rule->table;
 294         frh->res1 = 0;
 295         frh->res2 = 0;
 296         frh->action = rule->action;
 297         frh->flags = rule->flags;
 298
 299         if (rule->ifname[0])
 300                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 301
 302         if (rule->pref)
 303                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 304
 305         if (ops->fill(rule, skb, nlh, frh) < 0)
 306                 goto nla_put_failure;
 307
 308         return nlmsg_end(skb, nlh);
 309
 310 nla_put_failure:
 311         return nlmsg_cancel(skb, nlh);
 312 }
 313
 314 int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
 315 {
 316         int idx = 0;
 317         struct fib_rule *rule;
 318         struct fib_rules_ops *ops;
 319
 320         ops = lookup_rules_ops(family);
 321         if (ops == NULL)
 322                 return -EAFNOSUPPORT;
 323
 324         rcu_read_lock();
 325         list_for_each_entry(rule, ops->rules_list, list) {
 326                 if (idx < cb->args[0])
 327                         goto skip;
 328
 329                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 330                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 331                                      NLM_F_MULTI, ops) < 0)
 332                         break;
 333 skip:
 334                 idx++;
 335         }
 336         rcu_read_unlock();
 337         cb->args[0] = idx;
 338         rules_ops_put(ops);
 339
 340         return skb->len;
 341 }
 342
 343 EXPORT_SYMBOL_GPL(fib_rules_dump);
 344
 345 static void notify_rule_change(int event, struct fib_rule *rule,
 346                                struct fib_rules_ops *ops)
 347 {
 348         int size = nlmsg_total_size(sizeof(struct fib_rule_hdr) + 128);
 349         struct sk_buff *skb = alloc_skb(size, GFP_KERNEL);
 350
 351         if (skb == NULL)
 352                 netlink_set_err(rtnl, 0, ops->nlgroup, ENOBUFS);
 353         else if (fib_nl_fill_rule(skb, rule, 0, 0, event, 0, ops) < 0) {
 354                 kfree_skb(skb);
 355                 netlink_set_err(rtnl, 0, ops->nlgroup, EINVAL);
 356         } else
 357                 netlink_broadcast(rtnl, skb, 0, ops->nlgroup, GFP_KERNEL);
 358 }
 359
 360 static void attach_rules(struct list_head *rules, struct net_device *dev)
 361 {
 362         struct fib_rule *rule;
 363
 364         list_for_each_entry(rule, rules, list) {
 365                 if (rule->ifindex == -1 &&
 366                     strcmp(dev->name, rule->ifname) == 0)
 367                         rule->ifindex = dev->ifindex;
 368         }
 369 }
 370
 371 static void detach_rules(struct list_head *rules, struct net_device *dev)
 372 {
 373         struct fib_rule *rule;
 374
 375         list_for_each_entry(rule, rules, list)
 376                 if (rule->ifindex == dev->ifindex)
 377                         rule->ifindex = -1;
 378 }
 379
 380
 381 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 382                             void *ptr)
 383 {
 384         struct net_device *dev = ptr;
 385         struct fib_rules_ops *ops;
 386
 387         ASSERT_RTNL();
 388         rcu_read_lock();
 389
 390         switch (event) {
 391         case NETDEV_REGISTER:
 392                 list_for_each_entry(ops, &rules_ops, list)
 393                         attach_rules(ops->rules_list, dev);
 394                 break;
 395
 396         case NETDEV_UNREGISTER:
 397                 list_for_each_entry(ops, &rules_ops, list)
 398                         detach_rules(ops->rules_list, dev);
 399                 break;
 400         }
 401
 402         rcu_read_unlock();
 403
 404         return NOTIFY_DONE;
 405 }
 406
 407 static struct notifier_block fib_rules_notifier = {
 408         .notifier_call = fib_rules_event,
 409 };
 410
 411 static int __init fib_rules_init(void)
 412 {
 413         return register_netdevice_notifier(&fib_rules_notifier);
 414 }
 415
 416 subsys_initcall(fib_rules_init);