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