xref: /openbmc/linux/net/core/fib_rules.c (revision 089a49b6)
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/slab.h>
14 #include <linux/list.h>
15 #include <linux/module.h>
16 #include <net/net_namespace.h>
17 #include <net/sock.h>
18 #include <net/fib_rules.h>
19 
20 int fib_default_rule_add(struct fib_rules_ops *ops,
21 			 u32 pref, u32 table, u32 flags)
22 {
23 	struct fib_rule *r;
24 
25 	r = kzalloc(ops->rule_size, GFP_KERNEL);
26 	if (r == NULL)
27 		return -ENOMEM;
28 
29 	atomic_set(&r->refcnt, 1);
30 	r->action = FR_ACT_TO_TBL;
31 	r->pref = pref;
32 	r->table = table;
33 	r->flags = flags;
34 	r->fr_net = hold_net(ops->fro_net);
35 
36 	r->suppress_prefixlen = -1;
37 	r->suppress_ifgroup = -1;
38 
39 	/* The lock is not required here, the list in unreacheable
40 	 * at the moment this function is called */
41 	list_add_tail(&r->list, &ops->rules_list);
42 	return 0;
43 }
44 EXPORT_SYMBOL(fib_default_rule_add);
45 
46 u32 fib_default_rule_pref(struct fib_rules_ops *ops)
47 {
48 	struct list_head *pos;
49 	struct fib_rule *rule;
50 
51 	if (!list_empty(&ops->rules_list)) {
52 		pos = ops->rules_list.next;
53 		if (pos->next != &ops->rules_list) {
54 			rule = list_entry(pos->next, struct fib_rule, list);
55 			if (rule->pref)
56 				return rule->pref - 1;
57 		}
58 	}
59 
60 	return 0;
61 }
62 EXPORT_SYMBOL(fib_default_rule_pref);
63 
64 static void notify_rule_change(int event, struct fib_rule *rule,
65 			       struct fib_rules_ops *ops, struct nlmsghdr *nlh,
66 			       u32 pid);
67 
68 static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
69 {
70 	struct fib_rules_ops *ops;
71 
72 	rcu_read_lock();
73 	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
74 		if (ops->family == family) {
75 			if (!try_module_get(ops->owner))
76 				ops = NULL;
77 			rcu_read_unlock();
78 			return ops;
79 		}
80 	}
81 	rcu_read_unlock();
82 
83 	return NULL;
84 }
85 
86 static void rules_ops_put(struct fib_rules_ops *ops)
87 {
88 	if (ops)
89 		module_put(ops->owner);
90 }
91 
92 static void flush_route_cache(struct fib_rules_ops *ops)
93 {
94 	if (ops->flush_cache)
95 		ops->flush_cache(ops);
96 }
97 
98 static int __fib_rules_register(struct fib_rules_ops *ops)
99 {
100 	int err = -EEXIST;
101 	struct fib_rules_ops *o;
102 	struct net *net;
103 
104 	net = ops->fro_net;
105 
106 	if (ops->rule_size < sizeof(struct fib_rule))
107 		return -EINVAL;
108 
109 	if (ops->match == NULL || ops->configure == NULL ||
110 	    ops->compare == NULL || ops->fill == NULL ||
111 	    ops->action == NULL)
112 		return -EINVAL;
113 
114 	spin_lock(&net->rules_mod_lock);
115 	list_for_each_entry(o, &net->rules_ops, list)
116 		if (ops->family == o->family)
117 			goto errout;
118 
119 	hold_net(net);
120 	list_add_tail_rcu(&ops->list, &net->rules_ops);
121 	err = 0;
122 errout:
123 	spin_unlock(&net->rules_mod_lock);
124 
125 	return err;
126 }
127 
128 struct fib_rules_ops *
129 fib_rules_register(const struct fib_rules_ops *tmpl, struct net *net)
130 {
131 	struct fib_rules_ops *ops;
132 	int err;
133 
134 	ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
135 	if (ops == NULL)
136 		return ERR_PTR(-ENOMEM);
137 
138 	INIT_LIST_HEAD(&ops->rules_list);
139 	ops->fro_net = net;
140 
141 	err = __fib_rules_register(ops);
142 	if (err) {
143 		kfree(ops);
144 		ops = ERR_PTR(err);
145 	}
146 
147 	return ops;
148 }
149 EXPORT_SYMBOL_GPL(fib_rules_register);
150 
151 static void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
152 {
153 	struct fib_rule *rule, *tmp;
154 
155 	list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
156 		list_del_rcu(&rule->list);
157 		if (ops->delete)
158 			ops->delete(rule);
159 		fib_rule_put(rule);
160 	}
161 }
162 
163 static void fib_rules_put_rcu(struct rcu_head *head)
164 {
165 	struct fib_rules_ops *ops = container_of(head, struct fib_rules_ops, rcu);
166 	struct net *net = ops->fro_net;
167 
168 	release_net(net);
169 	kfree(ops);
170 }
171 
172 void fib_rules_unregister(struct fib_rules_ops *ops)
173 {
174 	struct net *net = ops->fro_net;
175 
176 	spin_lock(&net->rules_mod_lock);
177 	list_del_rcu(&ops->list);
178 	fib_rules_cleanup_ops(ops);
179 	spin_unlock(&net->rules_mod_lock);
180 
181 	call_rcu(&ops->rcu, fib_rules_put_rcu);
182 }
183 EXPORT_SYMBOL_GPL(fib_rules_unregister);
184 
185 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
186 			  struct flowi *fl, int flags)
187 {
188 	int ret = 0;
189 
190 	if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
191 		goto out;
192 
193 	if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
194 		goto out;
195 
196 	if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
197 		goto out;
198 
199 	ret = ops->match(rule, fl, flags);
200 out:
201 	return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
202 }
203 
204 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
205 		     int flags, struct fib_lookup_arg *arg)
206 {
207 	struct fib_rule *rule;
208 	int err;
209 
210 	rcu_read_lock();
211 
212 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
213 jumped:
214 		if (!fib_rule_match(rule, ops, fl, flags))
215 			continue;
216 
217 		if (rule->action == FR_ACT_GOTO) {
218 			struct fib_rule *target;
219 
220 			target = rcu_dereference(rule->ctarget);
221 			if (target == NULL) {
222 				continue;
223 			} else {
224 				rule = target;
225 				goto jumped;
226 			}
227 		} else if (rule->action == FR_ACT_NOP)
228 			continue;
229 		else
230 			err = ops->action(rule, fl, flags, arg);
231 
232 		if (!err && ops->suppress && ops->suppress(rule, arg))
233 			continue;
234 
235 		if (err != -EAGAIN) {
236 			if ((arg->flags & FIB_LOOKUP_NOREF) ||
237 			    likely(atomic_inc_not_zero(&rule->refcnt))) {
238 				arg->rule = rule;
239 				goto out;
240 			}
241 			break;
242 		}
243 	}
244 
245 	err = -ESRCH;
246 out:
247 	rcu_read_unlock();
248 
249 	return err;
250 }
251 EXPORT_SYMBOL_GPL(fib_rules_lookup);
252 
253 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
254 			    struct fib_rules_ops *ops)
255 {
256 	int err = -EINVAL;
257 
258 	if (frh->src_len)
259 		if (tb[FRA_SRC] == NULL ||
260 		    frh->src_len > (ops->addr_size * 8) ||
261 		    nla_len(tb[FRA_SRC]) != ops->addr_size)
262 			goto errout;
263 
264 	if (frh->dst_len)
265 		if (tb[FRA_DST] == NULL ||
266 		    frh->dst_len > (ops->addr_size * 8) ||
267 		    nla_len(tb[FRA_DST]) != ops->addr_size)
268 			goto errout;
269 
270 	err = 0;
271 errout:
272 	return err;
273 }
274 
275 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh)
276 {
277 	struct net *net = sock_net(skb->sk);
278 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
279 	struct fib_rules_ops *ops = NULL;
280 	struct fib_rule *rule, *r, *last = NULL;
281 	struct nlattr *tb[FRA_MAX+1];
282 	int err = -EINVAL, unresolved = 0;
283 
284 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
285 		goto errout;
286 
287 	ops = lookup_rules_ops(net, frh->family);
288 	if (ops == NULL) {
289 		err = -EAFNOSUPPORT;
290 		goto errout;
291 	}
292 
293 	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
294 	if (err < 0)
295 		goto errout;
296 
297 	err = validate_rulemsg(frh, tb, ops);
298 	if (err < 0)
299 		goto errout;
300 
301 	rule = kzalloc(ops->rule_size, GFP_KERNEL);
302 	if (rule == NULL) {
303 		err = -ENOMEM;
304 		goto errout;
305 	}
306 	rule->fr_net = hold_net(net);
307 
308 	if (tb[FRA_PRIORITY])
309 		rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
310 
311 	if (tb[FRA_IIFNAME]) {
312 		struct net_device *dev;
313 
314 		rule->iifindex = -1;
315 		nla_strlcpy(rule->iifname, tb[FRA_IIFNAME], IFNAMSIZ);
316 		dev = __dev_get_by_name(net, rule->iifname);
317 		if (dev)
318 			rule->iifindex = dev->ifindex;
319 	}
320 
321 	if (tb[FRA_OIFNAME]) {
322 		struct net_device *dev;
323 
324 		rule->oifindex = -1;
325 		nla_strlcpy(rule->oifname, tb[FRA_OIFNAME], IFNAMSIZ);
326 		dev = __dev_get_by_name(net, rule->oifname);
327 		if (dev)
328 			rule->oifindex = dev->ifindex;
329 	}
330 
331 	if (tb[FRA_FWMARK]) {
332 		rule->mark = nla_get_u32(tb[FRA_FWMARK]);
333 		if (rule->mark)
334 			/* compatibility: if the mark value is non-zero all bits
335 			 * are compared unless a mask is explicitly specified.
336 			 */
337 			rule->mark_mask = 0xFFFFFFFF;
338 	}
339 
340 	if (tb[FRA_FWMASK])
341 		rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
342 
343 	rule->action = frh->action;
344 	rule->flags = frh->flags;
345 	rule->table = frh_get_table(frh, tb);
346 	if (tb[FRA_SUPPRESS_PREFIXLEN])
347 		rule->suppress_prefixlen = nla_get_u32(tb[FRA_SUPPRESS_PREFIXLEN]);
348 	else
349 		rule->suppress_prefixlen = -1;
350 
351 	if (tb[FRA_SUPPRESS_IFGROUP])
352 		rule->suppress_ifgroup = nla_get_u32(tb[FRA_SUPPRESS_IFGROUP]);
353 	else
354 		rule->suppress_ifgroup = -1;
355 
356 	if (!tb[FRA_PRIORITY] && ops->default_pref)
357 		rule->pref = ops->default_pref(ops);
358 
359 	err = -EINVAL;
360 	if (tb[FRA_GOTO]) {
361 		if (rule->action != FR_ACT_GOTO)
362 			goto errout_free;
363 
364 		rule->target = nla_get_u32(tb[FRA_GOTO]);
365 		/* Backward jumps are prohibited to avoid endless loops */
366 		if (rule->target <= rule->pref)
367 			goto errout_free;
368 
369 		list_for_each_entry(r, &ops->rules_list, list) {
370 			if (r->pref == rule->target) {
371 				RCU_INIT_POINTER(rule->ctarget, r);
372 				break;
373 			}
374 		}
375 
376 		if (rcu_dereference_protected(rule->ctarget, 1) == NULL)
377 			unresolved = 1;
378 	} else if (rule->action == FR_ACT_GOTO)
379 		goto errout_free;
380 
381 	err = ops->configure(rule, skb, frh, tb);
382 	if (err < 0)
383 		goto errout_free;
384 
385 	list_for_each_entry(r, &ops->rules_list, list) {
386 		if (r->pref > rule->pref)
387 			break;
388 		last = r;
389 	}
390 
391 	fib_rule_get(rule);
392 
393 	if (last)
394 		list_add_rcu(&rule->list, &last->list);
395 	else
396 		list_add_rcu(&rule->list, &ops->rules_list);
397 
398 	if (ops->unresolved_rules) {
399 		/*
400 		 * There are unresolved goto rules in the list, check if
401 		 * any of them are pointing to this new rule.
402 		 */
403 		list_for_each_entry(r, &ops->rules_list, list) {
404 			if (r->action == FR_ACT_GOTO &&
405 			    r->target == rule->pref &&
406 			    rtnl_dereference(r->ctarget) == NULL) {
407 				rcu_assign_pointer(r->ctarget, rule);
408 				if (--ops->unresolved_rules == 0)
409 					break;
410 			}
411 		}
412 	}
413 
414 	if (rule->action == FR_ACT_GOTO)
415 		ops->nr_goto_rules++;
416 
417 	if (unresolved)
418 		ops->unresolved_rules++;
419 
420 	notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).portid);
421 	flush_route_cache(ops);
422 	rules_ops_put(ops);
423 	return 0;
424 
425 errout_free:
426 	release_net(rule->fr_net);
427 	kfree(rule);
428 errout:
429 	rules_ops_put(ops);
430 	return err;
431 }
432 
433 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh)
434 {
435 	struct net *net = sock_net(skb->sk);
436 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
437 	struct fib_rules_ops *ops = NULL;
438 	struct fib_rule *rule, *tmp;
439 	struct nlattr *tb[FRA_MAX+1];
440 	int err = -EINVAL;
441 
442 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
443 		goto errout;
444 
445 	ops = lookup_rules_ops(net, frh->family);
446 	if (ops == NULL) {
447 		err = -EAFNOSUPPORT;
448 		goto errout;
449 	}
450 
451 	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
452 	if (err < 0)
453 		goto errout;
454 
455 	err = validate_rulemsg(frh, tb, ops);
456 	if (err < 0)
457 		goto errout;
458 
459 	list_for_each_entry(rule, &ops->rules_list, list) {
460 		if (frh->action && (frh->action != rule->action))
461 			continue;
462 
463 		if (frh->table && (frh_get_table(frh, tb) != rule->table))
464 			continue;
465 
466 		if (tb[FRA_PRIORITY] &&
467 		    (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
468 			continue;
469 
470 		if (tb[FRA_IIFNAME] &&
471 		    nla_strcmp(tb[FRA_IIFNAME], rule->iifname))
472 			continue;
473 
474 		if (tb[FRA_OIFNAME] &&
475 		    nla_strcmp(tb[FRA_OIFNAME], rule->oifname))
476 			continue;
477 
478 		if (tb[FRA_FWMARK] &&
479 		    (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
480 			continue;
481 
482 		if (tb[FRA_FWMASK] &&
483 		    (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
484 			continue;
485 
486 		if (!ops->compare(rule, frh, tb))
487 			continue;
488 
489 		if (rule->flags & FIB_RULE_PERMANENT) {
490 			err = -EPERM;
491 			goto errout;
492 		}
493 
494 		list_del_rcu(&rule->list);
495 
496 		if (rule->action == FR_ACT_GOTO) {
497 			ops->nr_goto_rules--;
498 			if (rtnl_dereference(rule->ctarget) == NULL)
499 				ops->unresolved_rules--;
500 		}
501 
502 		/*
503 		 * Check if this rule is a target to any of them. If so,
504 		 * disable them. As this operation is eventually very
505 		 * expensive, it is only performed if goto rules have
506 		 * actually been added.
507 		 */
508 		if (ops->nr_goto_rules > 0) {
509 			list_for_each_entry(tmp, &ops->rules_list, list) {
510 				if (rtnl_dereference(tmp->ctarget) == rule) {
511 					RCU_INIT_POINTER(tmp->ctarget, NULL);
512 					ops->unresolved_rules++;
513 				}
514 			}
515 		}
516 
517 		notify_rule_change(RTM_DELRULE, rule, ops, nlh,
518 				   NETLINK_CB(skb).portid);
519 		if (ops->delete)
520 			ops->delete(rule);
521 		fib_rule_put(rule);
522 		flush_route_cache(ops);
523 		rules_ops_put(ops);
524 		return 0;
525 	}
526 
527 	err = -ENOENT;
528 errout:
529 	rules_ops_put(ops);
530 	return err;
531 }
532 
533 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
534 					 struct fib_rule *rule)
535 {
536 	size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
537 			 + nla_total_size(IFNAMSIZ) /* FRA_IIFNAME */
538 			 + nla_total_size(IFNAMSIZ) /* FRA_OIFNAME */
539 			 + nla_total_size(4) /* FRA_PRIORITY */
540 			 + nla_total_size(4) /* FRA_TABLE */
541 			 + nla_total_size(4) /* FRA_SUPPRESS_PREFIXLEN */
542 			 + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
543 			 + nla_total_size(4) /* FRA_FWMARK */
544 			 + nla_total_size(4); /* FRA_FWMASK */
545 
546 	if (ops->nlmsg_payload)
547 		payload += ops->nlmsg_payload(rule);
548 
549 	return payload;
550 }
551 
552 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
553 			    u32 pid, u32 seq, int type, int flags,
554 			    struct fib_rules_ops *ops)
555 {
556 	struct nlmsghdr *nlh;
557 	struct fib_rule_hdr *frh;
558 
559 	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
560 	if (nlh == NULL)
561 		return -EMSGSIZE;
562 
563 	frh = nlmsg_data(nlh);
564 	frh->family = ops->family;
565 	frh->table = rule->table;
566 	if (nla_put_u32(skb, FRA_TABLE, rule->table))
567 		goto nla_put_failure;
568 	if (nla_put_u32(skb, FRA_SUPPRESS_PREFIXLEN, rule->suppress_prefixlen))
569 		goto nla_put_failure;
570 	frh->res1 = 0;
571 	frh->res2 = 0;
572 	frh->action = rule->action;
573 	frh->flags = rule->flags;
574 
575 	if (rule->action == FR_ACT_GOTO &&
576 	    rcu_access_pointer(rule->ctarget) == NULL)
577 		frh->flags |= FIB_RULE_UNRESOLVED;
578 
579 	if (rule->iifname[0]) {
580 		if (nla_put_string(skb, FRA_IIFNAME, rule->iifname))
581 			goto nla_put_failure;
582 		if (rule->iifindex == -1)
583 			frh->flags |= FIB_RULE_IIF_DETACHED;
584 	}
585 
586 	if (rule->oifname[0]) {
587 		if (nla_put_string(skb, FRA_OIFNAME, rule->oifname))
588 			goto nla_put_failure;
589 		if (rule->oifindex == -1)
590 			frh->flags |= FIB_RULE_OIF_DETACHED;
591 	}
592 
593 	if ((rule->pref &&
594 	     nla_put_u32(skb, FRA_PRIORITY, rule->pref)) ||
595 	    (rule->mark &&
596 	     nla_put_u32(skb, FRA_FWMARK, rule->mark)) ||
597 	    ((rule->mark_mask || rule->mark) &&
598 	     nla_put_u32(skb, FRA_FWMASK, rule->mark_mask)) ||
599 	    (rule->target &&
600 	     nla_put_u32(skb, FRA_GOTO, rule->target)))
601 		goto nla_put_failure;
602 
603 	if (rule->suppress_ifgroup != -1) {
604 		if (nla_put_u32(skb, FRA_SUPPRESS_IFGROUP, rule->suppress_ifgroup))
605 			goto nla_put_failure;
606 	}
607 
608 	if (ops->fill(rule, skb, frh) < 0)
609 		goto nla_put_failure;
610 
611 	return nlmsg_end(skb, nlh);
612 
613 nla_put_failure:
614 	nlmsg_cancel(skb, nlh);
615 	return -EMSGSIZE;
616 }
617 
618 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
619 		      struct fib_rules_ops *ops)
620 {
621 	int idx = 0;
622 	struct fib_rule *rule;
623 
624 	rcu_read_lock();
625 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
626 		if (idx < cb->args[1])
627 			goto skip;
628 
629 		if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).portid,
630 				     cb->nlh->nlmsg_seq, RTM_NEWRULE,
631 				     NLM_F_MULTI, ops) < 0)
632 			break;
633 skip:
634 		idx++;
635 	}
636 	rcu_read_unlock();
637 	cb->args[1] = idx;
638 	rules_ops_put(ops);
639 
640 	return skb->len;
641 }
642 
643 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
644 {
645 	struct net *net = sock_net(skb->sk);
646 	struct fib_rules_ops *ops;
647 	int idx = 0, family;
648 
649 	family = rtnl_msg_family(cb->nlh);
650 	if (family != AF_UNSPEC) {
651 		/* Protocol specific dump request */
652 		ops = lookup_rules_ops(net, family);
653 		if (ops == NULL)
654 			return -EAFNOSUPPORT;
655 
656 		return dump_rules(skb, cb, ops);
657 	}
658 
659 	rcu_read_lock();
660 	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
661 		if (idx < cb->args[0] || !try_module_get(ops->owner))
662 			goto skip;
663 
664 		if (dump_rules(skb, cb, ops) < 0)
665 			break;
666 
667 		cb->args[1] = 0;
668 skip:
669 		idx++;
670 	}
671 	rcu_read_unlock();
672 	cb->args[0] = idx;
673 
674 	return skb->len;
675 }
676 
677 static void notify_rule_change(int event, struct fib_rule *rule,
678 			       struct fib_rules_ops *ops, struct nlmsghdr *nlh,
679 			       u32 pid)
680 {
681 	struct net *net;
682 	struct sk_buff *skb;
683 	int err = -ENOBUFS;
684 
685 	net = ops->fro_net;
686 	skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
687 	if (skb == NULL)
688 		goto errout;
689 
690 	err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
691 	if (err < 0) {
692 		/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
693 		WARN_ON(err == -EMSGSIZE);
694 		kfree_skb(skb);
695 		goto errout;
696 	}
697 
698 	rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
699 	return;
700 errout:
701 	if (err < 0)
702 		rtnl_set_sk_err(net, ops->nlgroup, err);
703 }
704 
705 static void attach_rules(struct list_head *rules, struct net_device *dev)
706 {
707 	struct fib_rule *rule;
708 
709 	list_for_each_entry(rule, rules, list) {
710 		if (rule->iifindex == -1 &&
711 		    strcmp(dev->name, rule->iifname) == 0)
712 			rule->iifindex = dev->ifindex;
713 		if (rule->oifindex == -1 &&
714 		    strcmp(dev->name, rule->oifname) == 0)
715 			rule->oifindex = dev->ifindex;
716 	}
717 }
718 
719 static void detach_rules(struct list_head *rules, struct net_device *dev)
720 {
721 	struct fib_rule *rule;
722 
723 	list_for_each_entry(rule, rules, list) {
724 		if (rule->iifindex == dev->ifindex)
725 			rule->iifindex = -1;
726 		if (rule->oifindex == dev->ifindex)
727 			rule->oifindex = -1;
728 	}
729 }
730 
731 
732 static int fib_rules_event(struct notifier_block *this, unsigned long event,
733 			   void *ptr)
734 {
735 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
736 	struct net *net = dev_net(dev);
737 	struct fib_rules_ops *ops;
738 
739 	ASSERT_RTNL();
740 
741 	switch (event) {
742 	case NETDEV_REGISTER:
743 		list_for_each_entry(ops, &net->rules_ops, list)
744 			attach_rules(&ops->rules_list, dev);
745 		break;
746 
747 	case NETDEV_UNREGISTER:
748 		list_for_each_entry(ops, &net->rules_ops, list)
749 			detach_rules(&ops->rules_list, dev);
750 		break;
751 	}
752 
753 	return NOTIFY_DONE;
754 }
755 
756 static struct notifier_block fib_rules_notifier = {
757 	.notifier_call = fib_rules_event,
758 };
759 
760 static int __net_init fib_rules_net_init(struct net *net)
761 {
762 	INIT_LIST_HEAD(&net->rules_ops);
763 	spin_lock_init(&net->rules_mod_lock);
764 	return 0;
765 }
766 
767 static struct pernet_operations fib_rules_net_ops = {
768 	.init = fib_rules_net_init,
769 };
770 
771 static int __init fib_rules_init(void)
772 {
773 	int err;
774 	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL, NULL);
775 	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL, NULL);
776 	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule, NULL);
777 
778 	err = register_pernet_subsys(&fib_rules_net_ops);
779 	if (err < 0)
780 		goto fail;
781 
782 	err = register_netdevice_notifier(&fib_rules_notifier);
783 	if (err < 0)
784 		goto fail_unregister;
785 
786 	return 0;
787 
788 fail_unregister:
789 	unregister_pernet_subsys(&fib_rules_net_ops);
790 fail:
791 	rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
792 	rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
793 	rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
794 	return err;
795 }
796 
797 subsys_initcall(fib_rules_init);
798