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/net_namespace.h>
15 #include <net/sock.h>
16 #include <net/fib_rules.h>
17
18 int fib_default_rule_add(struct fib_rules_ops *ops,
19 u32 pref, u32 table, u32 flags)
20 {
21 struct fib_rule *r;
22
23 r = kzalloc(ops->rule_size, GFP_KERNEL);
24 if (r == NULL)
25 return -ENOMEM;
26
27 atomic_set(&r->refcnt, 1);
28 r->action = FR_ACT_TO_TBL;
29 r->pref = pref;
30 r->table = table;
31 r->flags = flags;
32 r->fr_net = ops->fro_net;
33
34 /* The lock is not required here, the list in unreacheable
35 * at the moment this function is called */
36 list_add_tail(&r->list, &ops->rules_list);
37 return 0;
38 }
39 EXPORT_SYMBOL(fib_default_rule_add);
40
41 static void notify_rule_change(int event, struct fib_rule *rule,
42 struct fib_rules_ops *ops, struct nlmsghdr *nlh,
43 u32 pid);
44
45 static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
46 {
47 struct fib_rules_ops *ops;
48
49 rcu_read_lock();
50 list_for_each_entry_rcu(ops, &net->rules_ops, list) {
51 if (ops->family == family) {
52 if (!try_module_get(ops->owner))
53 ops = NULL;
54 rcu_read_unlock();
55 return ops;
56 }
57 }
58 rcu_read_unlock();
59
60 return NULL;
61 }
62
63 static void rules_ops_put(struct fib_rules_ops *ops)
64 {
65 if (ops)
66 module_put(ops->owner);
67 }
68
69 static void flush_route_cache(struct fib_rules_ops *ops)
70 {
71 if (ops->flush_cache)
72 ops->flush_cache();
73 }
74
75 int fib_rules_register(struct fib_rules_ops *ops)
76 {
77 int err = -EEXIST;
78 struct fib_rules_ops *o;
79 struct net *net;
80
81 net = ops->fro_net;
82
83 if (ops->rule_size < sizeof(struct fib_rule))
84 return -EINVAL;
85
86 if (ops->match == NULL || ops->configure == NULL ||
87 ops->compare == NULL || ops->fill == NULL ||
88 ops->action == NULL)
89 return -EINVAL;
90
91 spin_lock(&net->rules_mod_lock);
92 list_for_each_entry(o, &net->rules_ops, list)
93 if (ops->family == o->family)
94 goto errout;
95
96 hold_net(net);
97 list_add_tail_rcu(&ops->list, &net->rules_ops);
98 err = 0;
99 errout:
100 spin_unlock(&net->rules_mod_lock);
101
102 return err;
103 }
104
105 EXPORT_SYMBOL_GPL(fib_rules_register);
106
107 void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
108 {
109 struct fib_rule *rule, *tmp;
110
111 list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
112 list_del_rcu(&rule->list);
113 fib_rule_put(rule);
114 }
115 }
116 EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);
117
118 void fib_rules_unregister(struct fib_rules_ops *ops)
119 {
120 struct net *net = ops->fro_net;
121
122 spin_lock(&net->rules_mod_lock);
123 list_del_rcu(&ops->list);
124 fib_rules_cleanup_ops(ops);
125 spin_unlock(&net->rules_mod_lock);
126
127 synchronize_rcu();
128 release_net(net);
129 }
130
131 EXPORT_SYMBOL_GPL(fib_rules_unregister);
132
133 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
134 struct flowi *fl, int flags)
135 {
136 int ret = 0;
137
138 if (rule->ifindex && (rule->ifindex != fl->iif))
139 goto out;
140
141 if ((rule->mark ^ fl->mark) & rule->mark_mask)
142 goto out;
143
144 ret = ops->match(rule, fl, flags);
145 out:
146 return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
147 }
148
149 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
150 int flags, struct fib_lookup_arg *arg)
151 {
152 struct fib_rule *rule;
153 int err;
154
155 rcu_read_lock();
156
157 list_for_each_entry_rcu(rule, &ops->rules_list, list) {
158 jumped:
159 if (!fib_rule_match(rule, ops, fl, flags))
160 continue;
161
162 if (rule->action == FR_ACT_GOTO) {
163 struct fib_rule *target;
164
165 target = rcu_dereference(rule->ctarget);
166 if (target == NULL) {
167 continue;
168 } else {
169 rule = target;
170 goto jumped;
171 }
172 } else if (rule->action == FR_ACT_NOP)
173 continue;
174 else
175 err = ops->action(rule, fl, flags, arg);
176
177 if (err != -EAGAIN) {
178 fib_rule_get(rule);
179 arg->rule = rule;
180 goto out;
181 }
182 }
183
184 err = -ESRCH;
185 out:
186 rcu_read_unlock();
187
188 return err;
189 }
190
191 EXPORT_SYMBOL_GPL(fib_rules_lookup);
192
193 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
194 struct fib_rules_ops *ops)
195 {
196 int err = -EINVAL;
197
198 if (frh->src_len)
199 if (tb[FRA_SRC] == NULL ||
200 frh->src_len > (ops->addr_size * 8) ||
201 nla_len(tb[FRA_SRC]) != ops->addr_size)
202 goto errout;
203
204 if (frh->dst_len)
205 if (tb[FRA_DST] == NULL ||
206 frh->dst_len > (ops->addr_size * 8) ||
207 nla_len(tb[FRA_DST]) != ops->addr_size)
208 goto errout;
209
210 err = 0;
211 errout:
212 return err;
213 }
214
215 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
216 {
217 struct net *net = skb->sk->sk_net;
218 struct fib_rule_hdr *frh = nlmsg_data(nlh);
219 struct fib_rules_ops *ops = NULL;
220 struct fib_rule *rule, *r, *last = NULL;
221 struct nlattr *tb[FRA_MAX+1];
222 int err = -EINVAL, unresolved = 0;
223
224 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
225 goto errout;
226
227 ops = lookup_rules_ops(net, frh->family);
228 if (ops == NULL) {
229 err = EAFNOSUPPORT;
230 goto errout;
231 }
232
233 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
234 if (err < 0)
235 goto errout;
236
237 err = validate_rulemsg(frh, tb, ops);
238 if (err < 0)
239 goto errout;
240
241 rule = kzalloc(ops->rule_size, GFP_KERNEL);
242 if (rule == NULL) {
243 err = -ENOMEM;
244 goto errout;
245 }
246 rule->fr_net = net;
247
248 if (tb[FRA_PRIORITY])
249 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
250
251 if (tb[FRA_IFNAME]) {
252 struct net_device *dev;
253
254 rule->ifindex = -1;
255 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
256 dev = __dev_get_by_name(net, rule->ifname);
257 if (dev)
258 rule->ifindex = dev->ifindex;
259 }
260
261 if (tb[FRA_FWMARK]) {
262 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
263 if (rule->mark)
264 /* compatibility: if the mark value is non-zero all bits
265 * are compared unless a mask is explicitly specified.
266 */
267 rule->mark_mask = 0xFFFFFFFF;
268 }
269
270 if (tb[FRA_FWMASK])
271 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
272
273 rule->action = frh->action;
274 rule->flags = frh->flags;
275 rule->table = frh_get_table(frh, tb);
276
277 if (!rule->pref && ops->default_pref)
278 rule->pref = ops->default_pref(ops);
279
280 err = -EINVAL;
281 if (tb[FRA_GOTO]) {
282 if (rule->action != FR_ACT_GOTO)
283 goto errout_free;
284
285 rule->target = nla_get_u32(tb[FRA_GOTO]);
286 /* Backward jumps are prohibited to avoid endless loops */
287 if (rule->target <= rule->pref)
288 goto errout_free;
289
290 list_for_each_entry(r, &ops->rules_list, list) {
291 if (r->pref == rule->target) {
292 rule->ctarget = r;
293 break;
294 }
295 }
296
297 if (rule->ctarget == NULL)
298 unresolved = 1;
299 } else if (rule->action == FR_ACT_GOTO)
300 goto errout_free;
301
302 err = ops->configure(rule, skb, nlh, frh, tb);
303 if (err < 0)
304 goto errout_free;
305
306 list_for_each_entry(r, &ops->rules_list, list) {
307 if (r->pref > rule->pref)
308 break;
309 last = r;
310 }
311
312 fib_rule_get(rule);
313
314 if (ops->unresolved_rules) {
315 /*
316 * There are unresolved goto rules in the list, check if
317 * any of them are pointing to this new rule.
318 */
319 list_for_each_entry(r, &ops->rules_list, list) {
320 if (r->action == FR_ACT_GOTO &&
321 r->target == rule->pref) {
322 BUG_ON(r->ctarget != NULL);
323 rcu_assign_pointer(r->ctarget, rule);
324 if (--ops->unresolved_rules == 0)
325 break;
326 }
327 }
328 }
329
330 if (rule->action == FR_ACT_GOTO)
331 ops->nr_goto_rules++;
332
333 if (unresolved)
334 ops->unresolved_rules++;
335
336 if (last)
337 list_add_rcu(&rule->list, &last->list);
338 else
339 list_add_rcu(&rule->list, &ops->rules_list);
340
341 notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
342 flush_route_cache(ops);
343 rules_ops_put(ops);
344 return 0;
345
346 errout_free:
347 kfree(rule);
348 errout:
349 rules_ops_put(ops);
350 return err;
351 }
352
353 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
354 {
355 struct net *net = skb->sk->sk_net;
356 struct fib_rule_hdr *frh = nlmsg_data(nlh);
357 struct fib_rules_ops *ops = NULL;
358 struct fib_rule *rule, *tmp;
359 struct nlattr *tb[FRA_MAX+1];
360 int err = -EINVAL;
361
362 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
363 goto errout;
364
365 ops = lookup_rules_ops(net, frh->family);
366 if (ops == NULL) {
367 err = EAFNOSUPPORT;
368 goto errout;
369 }
370
371 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
372 if (err < 0)
373 goto errout;
374
375 err = validate_rulemsg(frh, tb, ops);
376 if (err < 0)
377 goto errout;
378
379 list_for_each_entry(rule, &ops->rules_list, list) {
380 if (frh->action && (frh->action != rule->action))
381 continue;
382
383 if (frh->table && (frh_get_table(frh, tb) != rule->table))
384 continue;
385
386 if (tb[FRA_PRIORITY] &&
387 (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
388 continue;
389
390 if (tb[FRA_IFNAME] &&
391 nla_strcmp(tb[FRA_IFNAME], rule->ifname))
392 continue;
393
394 if (tb[FRA_FWMARK] &&
395 (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
396 continue;
397
398 if (tb[FRA_FWMASK] &&
399 (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
400 continue;
401
402 if (!ops->compare(rule, frh, tb))
403 continue;
404
405 if (rule->flags & FIB_RULE_PERMANENT) {
406 err = -EPERM;
407 goto errout;
408 }
409
410 list_del_rcu(&rule->list);
411
412 if (rule->action == FR_ACT_GOTO)
413 ops->nr_goto_rules--;
414
415 /*
416 * Check if this rule is a target to any of them. If so,
417 * disable them. As this operation is eventually very
418 * expensive, it is only performed if goto rules have
419 * actually been added.
420 */
421 if (ops->nr_goto_rules > 0) {
422 list_for_each_entry(tmp, &ops->rules_list, list) {
423 if (tmp->ctarget == rule) {
424 rcu_assign_pointer(tmp->ctarget, NULL);
425 ops->unresolved_rules++;
426 }
427 }
428 }
429
430 synchronize_rcu();
431 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
432 NETLINK_CB(skb).pid);
433 fib_rule_put(rule);
434 flush_route_cache(ops);
435 rules_ops_put(ops);
436 return 0;
437 }
438
439 err = -ENOENT;
440 errout:
441 rules_ops_put(ops);
442 return err;
443 }
444
445 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
446 struct fib_rule *rule)
447 {
448 size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
449 + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
450 + nla_total_size(4) /* FRA_PRIORITY */
451 + nla_total_size(4) /* FRA_TABLE */
452 + nla_total_size(4) /* FRA_FWMARK */
453 + nla_total_size(4); /* FRA_FWMASK */
454
455 if (ops->nlmsg_payload)
456 payload += ops->nlmsg_payload(rule);
457
458 return payload;
459 }
460
461 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
462 u32 pid, u32 seq, int type, int flags,
463 struct fib_rules_ops *ops)
464 {
465 struct nlmsghdr *nlh;
466 struct fib_rule_hdr *frh;
467
468 nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
469 if (nlh == NULL)
470 return -EMSGSIZE;
471
472 frh = nlmsg_data(nlh);
473 frh->table = rule->table;
474 NLA_PUT_U32(skb, FRA_TABLE, rule->table);
475 frh->res1 = 0;
476 frh->res2 = 0;
477 frh->action = rule->action;
478 frh->flags = rule->flags;
479
480 if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
481 frh->flags |= FIB_RULE_UNRESOLVED;
482
483 if (rule->ifname[0]) {
484 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
485
486 if (rule->ifindex == -1)
487 frh->flags |= FIB_RULE_DEV_DETACHED;
488 }
489
490 if (rule->pref)
491 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
492
493 if (rule->mark)
494 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
495
496 if (rule->mark_mask || rule->mark)
497 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
498
499 if (rule->target)
500 NLA_PUT_U32(skb, FRA_GOTO, rule->target);
501
502 if (ops->fill(rule, skb, nlh, frh) < 0)
503 goto nla_put_failure;
504
505 return nlmsg_end(skb, nlh);
506
507 nla_put_failure:
508 nlmsg_cancel(skb, nlh);
509 return -EMSGSIZE;
510 }
511
512 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
513 struct fib_rules_ops *ops)
514 {
515 int idx = 0;
516 struct fib_rule *rule;
517
518 list_for_each_entry(rule, &ops->rules_list, list) {
519 if (idx < cb->args[1])
520 goto skip;
521
522 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
523 cb->nlh->nlmsg_seq, RTM_NEWRULE,
524 NLM_F_MULTI, ops) < 0)
525 break;
526 skip:
527 idx++;
528 }
529 cb->args[1] = idx;
530 rules_ops_put(ops);
531
532 return skb->len;
533 }
534
535 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
536 {
537 struct net *net = skb->sk->sk_net;
538 struct fib_rules_ops *ops;
539 int idx = 0, family;
540
541 family = rtnl_msg_family(cb->nlh);
542 if (family != AF_UNSPEC) {
543 /* Protocol specific dump request */
544 ops = lookup_rules_ops(net, family);
545 if (ops == NULL)
546 return -EAFNOSUPPORT;
547
548 return dump_rules(skb, cb, ops);
549 }
550
551 rcu_read_lock();
552 list_for_each_entry_rcu(ops, &net->rules_ops, list) {
553 if (idx < cb->args[0] || !try_module_get(ops->owner))
554 goto skip;
555
556 if (dump_rules(skb, cb, ops) < 0)
557 break;
558
559 cb->args[1] = 0;
560 skip:
561 idx++;
562 }
563 rcu_read_unlock();
564 cb->args[0] = idx;
565
566 return skb->len;
567 }
568
569 static void notify_rule_change(int event, struct fib_rule *rule,
570 struct fib_rules_ops *ops, struct nlmsghdr *nlh,
571 u32 pid)
572 {
573 struct net *net;
574 struct sk_buff *skb;
575 int err = -ENOBUFS;
576
577 net = ops->fro_net;
578 skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
579 if (skb == NULL)
580 goto errout;
581
582 err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
583 if (err < 0) {
584 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
585 WARN_ON(err == -EMSGSIZE);
586 kfree_skb(skb);
587 goto errout;
588 }
589
590 err = rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
591 errout:
592 if (err < 0)
593 rtnl_set_sk_err(net, ops->nlgroup, err);
594 }
595
596 static void attach_rules(struct list_head *rules, struct net_device *dev)
597 {
598 struct fib_rule *rule;
599
600 list_for_each_entry(rule, rules, list) {
601 if (rule->ifindex == -1 &&
602 strcmp(dev->name, rule->ifname) == 0)
603 rule->ifindex = dev->ifindex;
604 }
605 }
606
607 static void detach_rules(struct list_head *rules, struct net_device *dev)
608 {
609 struct fib_rule *rule;
610
611 list_for_each_entry(rule, rules, list)
612 if (rule->ifindex == dev->ifindex)
613 rule->ifindex = -1;
614 }
615
616
617 static int fib_rules_event(struct notifier_block *this, unsigned long event,
618 void *ptr)
619 {
620 struct net_device *dev = ptr;
621 struct net *net = dev->nd_net;
622 struct fib_rules_ops *ops;
623
624 ASSERT_RTNL();
625 rcu_read_lock();
626
627 switch (event) {
628 case NETDEV_REGISTER:
629 list_for_each_entry(ops, &net->rules_ops, list)
630 attach_rules(&ops->rules_list, dev);
631 break;
632
633 case NETDEV_UNREGISTER:
634 list_for_each_entry(ops, &net->rules_ops, list)
635 detach_rules(&ops->rules_list, dev);
636 break;
637 }
638
639 rcu_read_unlock();
640
641 return NOTIFY_DONE;
642 }
643
644 static struct notifier_block fib_rules_notifier = {
645 .notifier_call = fib_rules_event,
646 };
647
648 static int fib_rules_net_init(struct net *net)
649 {
650 INIT_LIST_HEAD(&net->rules_ops);
651 spin_lock_init(&net->rules_mod_lock);
652 return 0;
653 }
654
655 static struct pernet_operations fib_rules_net_ops = {
656 .init = fib_rules_net_init,
657 };
658
659 static int __init fib_rules_init(void)
660 {
661 int err;
662 rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
663 rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
664 rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
665
666 err = register_netdevice_notifier(&fib_rules_notifier);
667 if (err < 0)
668 goto fail;
669
670 err = register_pernet_subsys(&fib_rules_net_ops);
671 if (err < 0)
672 goto fail_unregister;
673 return 0;
674
675 fail_unregister:
676 unregister_netdevice_notifier(&fib_rules_notifier);
677 fail:
678 rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
679 rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
680 rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
681 return err;
682 }
683
684 subsys_initcall(fib_rules_init);
685
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