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   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 ((rule->mark ^ fl->mark) & rule->mark_mask)
 123                         continue;
 124
 125                 if (!ops->match(rule, fl, flags))
 126                         continue;
 127
 128                 err = ops->action(rule, fl, flags, arg);
 129                 if (err != -EAGAIN) {
 130                         fib_rule_get(rule);
 131                         arg->rule = rule;
 132                         goto out;
 133                 }
 134         }
 135
 136         err = -ENETUNREACH;
 137 out:
 138         rcu_read_unlock();
 139
 140         return err;
 141 }
 142
 143 EXPORT_SYMBOL_GPL(fib_rules_lookup);
 144
 145 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 146 {
 147         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 148         struct fib_rules_ops *ops = NULL;
 149         struct fib_rule *rule, *r, *last = NULL;
 150         struct nlattr *tb[FRA_MAX+1];
 151         int err = -EINVAL;
 152
 153         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 154                 goto errout;
 155
 156         ops = lookup_rules_ops(frh->family);
 157         if (ops == NULL) {
 158                 err = EAFNOSUPPORT;
 159                 goto errout;
 160         }
 161
 162         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 163         if (err < 0)
 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                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
 180                 dev = __dev_get_by_name(rule->ifname);
 181                 if (dev)
 182                         rule->ifindex = dev->ifindex;
 183         }
 184
 185         if (tb[FRA_FWMARK]) {
 186                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 187                 if (rule->mark)
 188                         /* compatibility: if the mark value is non-zero all bits
 189                          * are compared unless a mask is explicitly specified.
 190                          */
 191                         rule->mark_mask = 0xFFFFFFFF;
 192         }
 193
 194         if (tb[FRA_FWMASK])
 195                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
 196
 197         rule->action = frh->action;
 198         rule->flags = frh->flags;
 199         rule->table = frh_get_table(frh, tb);
 200
 201         if (!rule->pref && ops->default_pref)
 202                 rule->pref = ops->default_pref();
 203
 204         err = ops->configure(rule, skb, nlh, frh, tb);
 205         if (err < 0)
 206                 goto errout_free;
 207
 208         list_for_each_entry(r, ops->rules_list, list) {
 209                 if (r->pref > rule->pref)
 210                         break;
 211                 last = r;
 212         }
 213
 214         fib_rule_get(rule);
 215
 216         if (last)
 217                 list_add_rcu(&rule->list, &last->list);
 218         else
 219                 list_add_rcu(&rule->list, ops->rules_list);
 220
 221         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 222         rules_ops_put(ops);
 223         return 0;
 224
 225 errout_free:
 226         kfree(rule);
 227 errout:
 228         rules_ops_put(ops);
 229         return err;
 230 }
 231
 232 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 233 {
 234         struct fib_rule_hdr *frh = nlmsg_data(nlh);
 235         struct fib_rules_ops *ops = NULL;
 236         struct fib_rule *rule;
 237         struct nlattr *tb[FRA_MAX+1];
 238         int err = -EINVAL;
 239
 240         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 241                 goto errout;
 242
 243         ops = lookup_rules_ops(frh->family);
 244         if (ops == NULL) {
 245                 err = EAFNOSUPPORT;
 246                 goto errout;
 247         }
 248
 249         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 250         if (err < 0)
 251                 goto errout;
 252
 253         list_for_each_entry(rule, ops->rules_list, list) {
 254                 if (frh->action && (frh->action != rule->action))
 255                         continue;
 256
 257                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
 258                         continue;
 259
 260                 if (tb[FRA_PRIORITY] &&
 261                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 262                         continue;
 263
 264                 if (tb[FRA_IFNAME] &&
 265                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
 266                         continue;
 267
 268                 if (tb[FRA_FWMARK] &&
 269                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 270                         continue;
 271
 272                 if (tb[FRA_FWMASK] &&
 273                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 274                         continue;
 275
 276                 if (!ops->compare(rule, frh, tb))
 277                         continue;
 278
 279                 if (rule->flags & FIB_RULE_PERMANENT) {
 280                         err = -EPERM;
 281                         goto errout;
 282                 }
 283
 284                 list_del_rcu(&rule->list);
 285                 synchronize_rcu();
 286                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 287                                    NETLINK_CB(skb).pid);
 288                 fib_rule_put(rule);
 289                 rules_ops_put(ops);
 290                 return 0;
 291         }
 292
 293         err = -ENOENT;
 294 errout:
 295         rules_ops_put(ops);
 296         return err;
 297 }
 298
 299 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 300                             u32 pid, u32 seq, int type, int flags,
 301                             struct fib_rules_ops *ops)
 302 {
 303         struct nlmsghdr *nlh;
 304         struct fib_rule_hdr *frh;
 305
 306         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 307         if (nlh == NULL)
 308                 return -1;
 309
 310         frh = nlmsg_data(nlh);
 311         frh->table = rule->table;
 312         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 313         frh->res1 = 0;
 314         frh->res2 = 0;
 315         frh->action = rule->action;
 316         frh->flags = rule->flags;
 317
 318         if (rule->ifname[0])
 319                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 320
 321         if (rule->pref)
 322                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
 323
 324         if (rule->mark)
 325                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
 326
 327         if (rule->mark_mask || rule->mark)
 328                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 329
 330         if (ops->fill(rule, skb, nlh, frh) < 0)
 331                 goto nla_put_failure;
 332
 333         return nlmsg_end(skb, nlh);
 334
 335 nla_put_failure:
 336         return nlmsg_cancel(skb, nlh);
 337 }
 338
 339 int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
 340 {
 341         int idx = 0;
 342         struct fib_rule *rule;
 343         struct fib_rules_ops *ops;
 344
 345         ops = lookup_rules_ops(family);
 346         if (ops == NULL)
 347                 return -EAFNOSUPPORT;
 348
 349         rcu_read_lock();
 350         list_for_each_entry(rule, ops->rules_list, list) {
 351                 if (idx < cb->args[0])
 352                         goto skip;
 353
 354                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 355                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
 356                                      NLM_F_MULTI, ops) < 0)
 357                         break;
 358 skip:
 359                 idx++;
 360         }
 361         rcu_read_unlock();
 362         cb->args[0] = idx;
 363         rules_ops_put(ops);
 364
 365         return skb->len;
 366 }
 367
 368 EXPORT_SYMBOL_GPL(fib_rules_dump);
 369
 370 static void notify_rule_change(int event, struct fib_rule *rule,
 371                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 372                                u32 pid)
 373 {
 374         struct sk_buff *skb;
 375         int err = -ENOBUFS;
 376
 377         skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
 378         if (skb == NULL)
 379                 goto errout;
 380
 381         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 382         if (err < 0) {
 383                 kfree_skb(skb);
 384                 goto errout;
 385         }
 386
 387         err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
 388 errout:
 389         if (err < 0)
 390                 rtnl_set_sk_err(ops->nlgroup, err);
 391 }
 392
 393 static void attach_rules(struct list_head *rules, struct net_device *dev)
 394 {
 395         struct fib_rule *rule;
 396
 397         list_for_each_entry(rule, rules, list) {
 398                 if (rule->ifindex == -1 &&
 399                     strcmp(dev->name, rule->ifname) == 0)
 400                         rule->ifindex = dev->ifindex;
 401         }
 402 }
 403
 404 static void detach_rules(struct list_head *rules, struct net_device *dev)
 405 {
 406         struct fib_rule *rule;
 407
 408         list_for_each_entry(rule, rules, list)
 409                 if (rule->ifindex == dev->ifindex)
 410                         rule->ifindex = -1;
 411 }
 412
 413
 414 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 415                             void *ptr)
 416 {
 417         struct net_device *dev = ptr;
 418         struct fib_rules_ops *ops;
 419
 420         ASSERT_RTNL();
 421         rcu_read_lock();
 422
 423         switch (event) {
 424         case NETDEV_REGISTER:
 425                 list_for_each_entry(ops, &rules_ops, list)
 426                         attach_rules(ops->rules_list, dev);
 427                 break;
 428
 429         case NETDEV_UNREGISTER:
 430                 list_for_each_entry(ops, &rules_ops, list)
 431                         detach_rules(ops->rules_list, dev);
 432                 break;
 433         }
 434
 435         rcu_read_unlock();
 436
 437         return NOTIFY_DONE;
 438 }
 439
 440 static struct notifier_block fib_rules_notifier = {
 441         .notifier_call = fib_rules_event,
 442 };
 443
 444 static int __init fib_rules_init(void)
 445 {
 446         return register_netdevice_notifier(&fib_rules_notifier);
 447 }
 448
 449 subsys_initcall(fib_rules_init);