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 = hold_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(ops);
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 = sock_net(skb->sk);
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 = hold_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, 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 release_net(rule->fr_net);
348 kfree(rule);
349 errout:
350 rules_ops_put(ops);
351 return err;
352 }
353
354 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
355 {
356 struct net *net = sock_net(skb->sk);
357 struct fib_rule_hdr *frh = nlmsg_data(nlh);
358 struct fib_rules_ops *ops = NULL;
359 struct fib_rule *rule, *tmp;
360 struct nlattr *tb[FRA_MAX+1];
361 int err = -EINVAL;
362
363 if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
364 goto errout;
365
366 ops = lookup_rules_ops(net, frh->family);
367 if (ops == NULL) {
368 err = -EAFNOSUPPORT;
369 goto errout;
370 }
371
372 err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
373 if (err < 0)
374 goto errout;
375
376 err = validate_rulemsg(frh, tb, ops);
377 if (err < 0)
378 goto errout;
379
380 list_for_each_entry(rule, &ops->rules_list, list) {
381 if (frh->action && (frh->action != rule->action))
382 continue;
383
384 if (frh->table && (frh_get_table(frh, tb) != rule->table))
385 continue;
386
387 if (tb[FRA_PRIORITY] &&
388 (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
389 continue;
390
391 if (tb[FRA_IFNAME] &&
392 nla_strcmp(tb[FRA_IFNAME], rule->ifname))
393 continue;
394
395 if (tb[FRA_FWMARK] &&
396 (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
397 continue;
398
399 if (tb[FRA_FWMASK] &&
400 (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
401 continue;
402
403 if (!ops->compare(rule, frh, tb))
404 continue;
405
406 if (rule->flags & FIB_RULE_PERMANENT) {
407 err = -EPERM;
408 goto errout;
409 }
410
411 list_del_rcu(&rule->list);
412
413 if (rule->action == FR_ACT_GOTO)
414 ops->nr_goto_rules--;
415
416 /*
417 * Check if this rule is a target to any of them. If so,
418 * disable them. As this operation is eventually very
419 * expensive, it is only performed if goto rules have
420 * actually been added.
421 */
422 if (ops->nr_goto_rules > 0) {
423 list_for_each_entry(tmp, &ops->rules_list, list) {
424 if (tmp->ctarget == rule) {
425 rcu_assign_pointer(tmp->ctarget, NULL);
426 ops->unresolved_rules++;
427 }
428 }
429 }
430
431 synchronize_rcu();
432 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
433 NETLINK_CB(skb).pid);
434 fib_rule_put(rule);
435 flush_route_cache(ops);
436 rules_ops_put(ops);
437 return 0;
438 }
439
440 err = -ENOENT;
441 errout:
442 rules_ops_put(ops);
443 return err;
444 }
445
446 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
447 struct fib_rule *rule)
448 {
449 size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
450 + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
451 + nla_total_size(4) /* FRA_PRIORITY */
452 + nla_total_size(4) /* FRA_TABLE */
453 + nla_total_size(4) /* FRA_FWMARK */
454 + nla_total_size(4); /* FRA_FWMASK */
455
456 if (ops->nlmsg_payload)
457 payload += ops->nlmsg_payload(rule);
458
459 return payload;
460 }
461
462 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
463 u32 pid, u32 seq, int type, int flags,
464 struct fib_rules_ops *ops)
465 {
466 struct nlmsghdr *nlh;
467 struct fib_rule_hdr *frh;
468
469 nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
470 if (nlh == NULL)
471 return -EMSGSIZE;
472
473 frh = nlmsg_data(nlh);
474 frh->table = rule->table;
475 NLA_PUT_U32(skb, FRA_TABLE, rule->table);
476 frh->res1 = 0;
477 frh->res2 = 0;
478 frh->action = rule->action;
479 frh->flags = rule->flags;
480
481 if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
482 frh->flags |= FIB_RULE_UNRESOLVED;
483
484 if (rule->ifname[0]) {
485 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
486
487 if (rule->ifindex == -1)
488 frh->flags |= FIB_RULE_DEV_DETACHED;
489 }
490
491 if (rule->pref)
492 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
493
494 if (rule->mark)
495 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
496
497 if (rule->mark_mask || rule->mark)
498 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
499
500 if (rule->target)
501 NLA_PUT_U32(skb, FRA_GOTO, rule->target);
502
503 if (ops->fill(rule, skb, frh) < 0)
504 goto nla_put_failure;
505
506 return nlmsg_end(skb, nlh);
507
508 nla_put_failure:
509 nlmsg_cancel(skb, nlh);
510 return -EMSGSIZE;
511 }
512
513 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
514 struct fib_rules_ops *ops)
515 {
516 int idx = 0;
517 struct fib_rule *rule;
518
519 list_for_each_entry(rule, &ops->rules_list, list) {
520 if (idx < cb->args[1])
521 goto skip;
522
523 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
524 cb->nlh->nlmsg_seq, RTM_NEWRULE,
525 NLM_F_MULTI, ops) < 0)
526 break;
527 skip:
528 idx++;
529 }
530 cb->args[1] = idx;
531 rules_ops_put(ops);
532
533 return skb->len;
534 }
535
536 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
537 {
538 struct net *net = sock_net(skb->sk);
539 struct fib_rules_ops *ops;
540 int idx = 0, family;
541
542 family = rtnl_msg_family(cb->nlh);
543 if (family != AF_UNSPEC) {
544 /* Protocol specific dump request */
545 ops = lookup_rules_ops(net, family);
546 if (ops == NULL)
547 return -EAFNOSUPPORT;
548
549 return dump_rules(skb, cb, ops);
550 }
551
552 rcu_read_lock();
553 list_for_each_entry_rcu(ops, &net->rules_ops, list) {
554 if (idx < cb->args[0] || !try_module_get(ops->owner))
555 goto skip;
556
557 if (dump_rules(skb, cb, ops) < 0)
558 break;
559
560 cb->args[1] = 0;
561 skip:
562 idx++;
563 }
564 rcu_read_unlock();
565 cb->args[0] = idx;
566
567 return skb->len;
568 }
569
570 static void notify_rule_change(int event, struct fib_rule *rule,
571 struct fib_rules_ops *ops, struct nlmsghdr *nlh,
572 u32 pid)
573 {
574 struct net *net;
575 struct sk_buff *skb;
576 int err = -ENOBUFS;
577
578 net = ops->fro_net;
579 skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
580 if (skb == NULL)
581 goto errout;
582
583 err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
584 if (err < 0) {
585 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
586 WARN_ON(err == -EMSGSIZE);
587 kfree_skb(skb);
588 goto errout;
589 }
590
591 rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
592 return;
593 errout:
594 if (err < 0)
595 rtnl_set_sk_err(net, ops->nlgroup, err);
596 }
597
598 static void attach_rules(struct list_head *rules, struct net_device *dev)
599 {
600 struct fib_rule *rule;
601
602 list_for_each_entry(rule, rules, list) {
603 if (rule->ifindex == -1 &&
604 strcmp(dev->name, rule->ifname) == 0)
605 rule->ifindex = dev->ifindex;
606 }
607 }
608
609 static void detach_rules(struct list_head *rules, struct net_device *dev)
610 {
611 struct fib_rule *rule;
612
613 list_for_each_entry(rule, rules, list)
614 if (rule->ifindex == dev->ifindex)
615 rule->ifindex = -1;
616 }
617
618
619 static int fib_rules_event(struct notifier_block *this, unsigned long event,
620 void *ptr)
621 {
622 struct net_device *dev = ptr;
623 struct net *net = dev_net(dev);
624 struct fib_rules_ops *ops;
625
626 ASSERT_RTNL();
627 rcu_read_lock();
628
629 switch (event) {
630 case NETDEV_REGISTER:
631 list_for_each_entry(ops, &net->rules_ops, list)
632 attach_rules(&ops->rules_list, dev);
633 break;
634
635 case NETDEV_UNREGISTER:
636 list_for_each_entry(ops, &net->rules_ops, list)
637 detach_rules(&ops->rules_list, dev);
638 break;
639 }
640
641 rcu_read_unlock();
642
643 return NOTIFY_DONE;
644 }
645
646 static struct notifier_block fib_rules_notifier = {
647 .notifier_call = fib_rules_event,
648 };
649
650 static int fib_rules_net_init(struct net *net)
651 {
652 INIT_LIST_HEAD(&net->rules_ops);
653 spin_lock_init(&net->rules_mod_lock);
654 return 0;
655 }
656
657 static struct pernet_operations fib_rules_net_ops = {
658 .init = fib_rules_net_init,
659 };
660
661 static int __init fib_rules_init(void)
662 {
663 int err;
664 rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
665 rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
666 rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
667
668 err = register_pernet_subsys(&fib_rules_net_ops);
669 if (err < 0)
670 goto fail;
671
672 err = register_netdevice_notifier(&fib_rules_notifier);
673 if (err < 0)
674 goto fail_unregister;
675
676 return 0;
677
678 fail_unregister:
679 unregister_pernet_subsys(&fib_rules_net_ops);
680 fail:
681 rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
682 rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
683 rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
684 return err;
685 }
686
687 subsys_initcall(fib_rules_init);
688
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