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