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