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