[IPV4/IPV6/DECNET]: Small cleanup for fib rules.
[linux-2.6.git] / net / core / fib_rules.c
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 static LIST_HEAD(rules_ops);
19 static DEFINE_SPINLOCK(rules_mod_lock);
20
21 static void notify_rule_change(int event, struct fib_rule *rule,
22                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
23                                u32 pid);
24
25 static struct fib_rules_ops *lookup_rules_ops(int family)
26 {
27         struct fib_rules_ops *ops;
28
29         rcu_read_lock();
30         list_for_each_entry_rcu(ops, &rules_ops, list) {
31                 if (ops->family == family) {
32                         if (!try_module_get(ops->owner))
33                                 ops = NULL;
34                         rcu_read_unlock();
35                         return ops;
36                 }
37         }
38         rcu_read_unlock();
39
40         return NULL;
41 }
42
43 static void rules_ops_put(struct fib_rules_ops *ops)
44 {
45         if (ops)
46                 module_put(ops->owner);
47 }
48
49 static void flush_route_cache(struct fib_rules_ops *ops)
50 {
51         if (ops->flush_cache)
52                 ops->flush_cache();
53 }
54
55 int fib_rules_register(struct fib_rules_ops *ops)
56 {
57         int err = -EEXIST;
58         struct fib_rules_ops *o;
59
60         if (ops->rule_size < sizeof(struct fib_rule))
61                 return -EINVAL;
62
63         if (ops->match == NULL || ops->configure == NULL ||
64             ops->compare == NULL || ops->fill == NULL ||
65             ops->action == NULL)
66                 return -EINVAL;
67
68         spin_lock(&rules_mod_lock);
69         list_for_each_entry(o, &rules_ops, list)
70                 if (ops->family == o->family)
71                         goto errout;
72
73         list_add_tail_rcu(&ops->list, &rules_ops);
74         err = 0;
75 errout:
76         spin_unlock(&rules_mod_lock);
77
78         return err;
79 }
80
81 EXPORT_SYMBOL_GPL(fib_rules_register);
82
83 static void cleanup_ops(struct fib_rules_ops *ops)
84 {
85         struct fib_rule *rule, *tmp;
86
87         list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
88                 list_del_rcu(&rule->list);
89                 fib_rule_put(rule);
90         }
91 }
92
93 int fib_rules_unregister(struct fib_rules_ops *ops)
94 {
95         int err = 0;
96         struct fib_rules_ops *o;
97
98         spin_lock(&rules_mod_lock);
99         list_for_each_entry(o, &rules_ops, list) {
100                 if (o == ops) {
101                         list_del_rcu(&o->list);
102                         cleanup_ops(ops);
103                         goto out;
104                 }
105         }
106
107         err = -ENOENT;
108 out:
109         spin_unlock(&rules_mod_lock);
110
111         synchronize_rcu();
112
113         return err;
114 }
115
116 EXPORT_SYMBOL_GPL(fib_rules_unregister);
117
118 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
119                           struct flowi *fl, int flags)
120 {
121         int ret = 0;
122
123         if (rule->ifindex && (rule->ifindex != fl->iif))
124                 goto out;
125
126         if ((rule->mark ^ fl->mark) & rule->mark_mask)
127                 goto out;
128
129         ret = ops->match(rule, fl, flags);
130 out:
131         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
132 }
133
134 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
135                      int flags, struct fib_lookup_arg *arg)
136 {
137         struct fib_rule *rule;
138         int err;
139
140         rcu_read_lock();
141
142         list_for_each_entry_rcu(rule, &ops->rules_list, list) {
143 jumped:
144                 if (!fib_rule_match(rule, ops, fl, flags))
145                         continue;
146
147                 if (rule->action == FR_ACT_GOTO) {
148                         struct fib_rule *target;
149
150                         target = rcu_dereference(rule->ctarget);
151                         if (target == NULL) {
152                                 continue;
153                         } else {
154                                 rule = target;
155                                 goto jumped;
156                         }
157                 } else if (rule->action == FR_ACT_NOP)
158                         continue;
159                 else
160                         err = ops->action(rule, fl, flags, arg);
161
162                 if (err != -EAGAIN) {
163                         fib_rule_get(rule);
164                         arg->rule = rule;
165                         goto out;
166                 }
167         }
168
169         err = -ESRCH;
170 out:
171         rcu_read_unlock();
172
173         return err;
174 }
175
176 EXPORT_SYMBOL_GPL(fib_rules_lookup);
177
178 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
179                             struct fib_rules_ops *ops)
180 {
181         int err = -EINVAL;
182
183         if (frh->src_len)
184                 if (tb[FRA_SRC] == NULL ||
185                     frh->src_len > (ops->addr_size * 8) ||
186                     nla_len(tb[FRA_SRC]) != ops->addr_size)
187                         goto errout;
188
189         if (frh->dst_len)
190                 if (tb[FRA_DST] == NULL ||
191                     frh->dst_len > (ops->addr_size * 8) ||
192                     nla_len(tb[FRA_DST]) != ops->addr_size)
193                         goto errout;
194
195         err = 0;
196 errout:
197         return err;
198 }
199
200 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
201 {
202         struct net *net = skb->sk->sk_net;
203         struct fib_rule_hdr *frh = nlmsg_data(nlh);
204         struct fib_rules_ops *ops = NULL;
205         struct fib_rule *rule, *r, *last = NULL;
206         struct nlattr *tb[FRA_MAX+1];
207         int err = -EINVAL, unresolved = 0;
208
209         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
210                 goto errout;
211
212         ops = lookup_rules_ops(frh->family);
213         if (ops == NULL) {
214                 err = EAFNOSUPPORT;
215                 goto errout;
216         }
217
218         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
219         if (err < 0)
220                 goto errout;
221
222         err = validate_rulemsg(frh, tb, ops);
223         if (err < 0)
224                 goto errout;
225
226         rule = kzalloc(ops->rule_size, GFP_KERNEL);
227         if (rule == NULL) {
228                 err = -ENOMEM;
229                 goto errout;
230         }
231
232         if (tb[FRA_PRIORITY])
233                 rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
234
235         if (tb[FRA_IFNAME]) {
236                 struct net_device *dev;
237
238                 rule->ifindex = -1;
239                 nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
240                 dev = __dev_get_by_name(net, rule->ifname);
241                 if (dev)
242                         rule->ifindex = dev->ifindex;
243         }
244
245         if (tb[FRA_FWMARK]) {
246                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
247                 if (rule->mark)
248                         /* compatibility: if the mark value is non-zero all bits
249                          * are compared unless a mask is explicitly specified.
250                          */
251                         rule->mark_mask = 0xFFFFFFFF;
252         }
253
254         if (tb[FRA_FWMASK])
255                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
256
257         rule->action = frh->action;
258         rule->flags = frh->flags;
259         rule->table = frh_get_table(frh, tb);
260
261         if (!rule->pref && ops->default_pref)
262                 rule->pref = ops->default_pref();
263
264         err = -EINVAL;
265         if (tb[FRA_GOTO]) {
266                 if (rule->action != FR_ACT_GOTO)
267                         goto errout_free;
268
269                 rule->target = nla_get_u32(tb[FRA_GOTO]);
270                 /* Backward jumps are prohibited to avoid endless loops */
271                 if (rule->target <= rule->pref)
272                         goto errout_free;
273
274                 list_for_each_entry(r, &ops->rules_list, list) {
275                         if (r->pref == rule->target) {
276                                 rule->ctarget = r;
277                                 break;
278                         }
279                 }
280
281                 if (rule->ctarget == NULL)
282                         unresolved = 1;
283         } else if (rule->action == FR_ACT_GOTO)
284                 goto errout_free;
285
286         err = ops->configure(rule, skb, nlh, frh, tb);
287         if (err < 0)
288                 goto errout_free;
289
290         list_for_each_entry(r, &ops->rules_list, list) {
291                 if (r->pref > rule->pref)
292                         break;
293                 last = r;
294         }
295
296         fib_rule_get(rule);
297
298         if (ops->unresolved_rules) {
299                 /*
300                  * There are unresolved goto rules in the list, check if
301                  * any of them are pointing to this new rule.
302                  */
303                 list_for_each_entry(r, &ops->rules_list, list) {
304                         if (r->action == FR_ACT_GOTO &&
305                             r->target == rule->pref) {
306                                 BUG_ON(r->ctarget != NULL);
307                                 rcu_assign_pointer(r->ctarget, rule);
308                                 if (--ops->unresolved_rules == 0)
309                                         break;
310                         }
311                 }
312         }
313
314         if (rule->action == FR_ACT_GOTO)
315                 ops->nr_goto_rules++;
316
317         if (unresolved)
318                 ops->unresolved_rules++;
319
320         if (last)
321                 list_add_rcu(&rule->list, &last->list);
322         else
323                 list_add_rcu(&rule->list, &ops->rules_list);
324
325         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
326         flush_route_cache(ops);
327         rules_ops_put(ops);
328         return 0;
329
330 errout_free:
331         kfree(rule);
332 errout:
333         rules_ops_put(ops);
334         return err;
335 }
336
337 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
338 {
339         struct fib_rule_hdr *frh = nlmsg_data(nlh);
340         struct fib_rules_ops *ops = NULL;
341         struct fib_rule *rule, *tmp;
342         struct nlattr *tb[FRA_MAX+1];
343         int err = -EINVAL;
344
345         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
346                 goto errout;
347
348         ops = lookup_rules_ops(frh->family);
349         if (ops == NULL) {
350                 err = EAFNOSUPPORT;
351                 goto errout;
352         }
353
354         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
355         if (err < 0)
356                 goto errout;
357
358         err = validate_rulemsg(frh, tb, ops);
359         if (err < 0)
360                 goto errout;
361
362         list_for_each_entry(rule, &ops->rules_list, list) {
363                 if (frh->action && (frh->action != rule->action))
364                         continue;
365
366                 if (frh->table && (frh_get_table(frh, tb) != rule->table))
367                         continue;
368
369                 if (tb[FRA_PRIORITY] &&
370                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
371                         continue;
372
373                 if (tb[FRA_IFNAME] &&
374                     nla_strcmp(tb[FRA_IFNAME], rule->ifname))
375                         continue;
376
377                 if (tb[FRA_FWMARK] &&
378                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
379                         continue;
380
381                 if (tb[FRA_FWMASK] &&
382                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
383                         continue;
384
385                 if (!ops->compare(rule, frh, tb))
386                         continue;
387
388                 if (rule->flags & FIB_RULE_PERMANENT) {
389                         err = -EPERM;
390                         goto errout;
391                 }
392
393                 list_del_rcu(&rule->list);
394
395                 if (rule->action == FR_ACT_GOTO)
396                         ops->nr_goto_rules--;
397
398                 /*
399                  * Check if this rule is a target to any of them. If so,
400                  * disable them. As this operation is eventually very
401                  * expensive, it is only performed if goto rules have
402                  * actually been added.
403                  */
404                 if (ops->nr_goto_rules > 0) {
405                         list_for_each_entry(tmp, &ops->rules_list, list) {
406                                 if (tmp->ctarget == rule) {
407                                         rcu_assign_pointer(tmp->ctarget, NULL);
408                                         ops->unresolved_rules++;
409                                 }
410                         }
411                 }
412
413                 synchronize_rcu();
414                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
415                                    NETLINK_CB(skb).pid);
416                 fib_rule_put(rule);
417                 flush_route_cache(ops);
418                 rules_ops_put(ops);
419                 return 0;
420         }
421
422         err = -ENOENT;
423 errout:
424         rules_ops_put(ops);
425         return err;
426 }
427
428 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
429                                          struct fib_rule *rule)
430 {
431         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
432                          + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
433                          + nla_total_size(4) /* FRA_PRIORITY */
434                          + nla_total_size(4) /* FRA_TABLE */
435                          + nla_total_size(4) /* FRA_FWMARK */
436                          + nla_total_size(4); /* FRA_FWMASK */
437
438         if (ops->nlmsg_payload)
439                 payload += ops->nlmsg_payload(rule);
440
441         return payload;
442 }
443
444 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
445                             u32 pid, u32 seq, int type, int flags,
446                             struct fib_rules_ops *ops)
447 {
448         struct nlmsghdr *nlh;
449         struct fib_rule_hdr *frh;
450
451         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
452         if (nlh == NULL)
453                 return -EMSGSIZE;
454
455         frh = nlmsg_data(nlh);
456         frh->table = rule->table;
457         NLA_PUT_U32(skb, FRA_TABLE, rule->table);
458         frh->res1 = 0;
459         frh->res2 = 0;
460         frh->action = rule->action;
461         frh->flags = rule->flags;
462
463         if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
464                 frh->flags |= FIB_RULE_UNRESOLVED;
465
466         if (rule->ifname[0]) {
467                 NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
468
469                 if (rule->ifindex == -1)
470                         frh->flags |= FIB_RULE_DEV_DETACHED;
471         }
472
473         if (rule->pref)
474                 NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
475
476         if (rule->mark)
477                 NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
478
479         if (rule->mark_mask || rule->mark)
480                 NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
481
482         if (rule->target)
483                 NLA_PUT_U32(skb, FRA_GOTO, rule->target);
484
485         if (ops->fill(rule, skb, nlh, frh) < 0)
486                 goto nla_put_failure;
487
488         return nlmsg_end(skb, nlh);
489
490 nla_put_failure:
491         nlmsg_cancel(skb, nlh);
492         return -EMSGSIZE;
493 }
494
495 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
496                       struct fib_rules_ops *ops)
497 {
498         int idx = 0;
499         struct fib_rule *rule;
500
501         list_for_each_entry(rule, &ops->rules_list, list) {
502                 if (idx < cb->args[1])
503                         goto skip;
504
505                 if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
506                                      cb->nlh->nlmsg_seq, RTM_NEWRULE,
507                                      NLM_F_MULTI, ops) < 0)
508                         break;
509 skip:
510                 idx++;
511         }
512         cb->args[1] = idx;
513         rules_ops_put(ops);
514
515         return skb->len;
516 }
517
518 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
519 {
520         struct fib_rules_ops *ops;
521         int idx = 0, family;
522
523         family = rtnl_msg_family(cb->nlh);
524         if (family != AF_UNSPEC) {
525                 /* Protocol specific dump request */
526                 ops = lookup_rules_ops(family);
527                 if (ops == NULL)
528                         return -EAFNOSUPPORT;
529
530                 return dump_rules(skb, cb, ops);
531         }
532
533         rcu_read_lock();
534         list_for_each_entry_rcu(ops, &rules_ops, list) {
535                 if (idx < cb->args[0] || !try_module_get(ops->owner))
536                         goto skip;
537
538                 if (dump_rules(skb, cb, ops) < 0)
539                         break;
540
541                 cb->args[1] = 0;
542         skip:
543                 idx++;
544         }
545         rcu_read_unlock();
546         cb->args[0] = idx;
547
548         return skb->len;
549 }
550
551 static void notify_rule_change(int event, struct fib_rule *rule,
552                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
553                                u32 pid)
554 {
555         struct sk_buff *skb;
556         int err = -ENOBUFS;
557
558         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
559         if (skb == NULL)
560                 goto errout;
561
562         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
563         if (err < 0) {
564                 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
565                 WARN_ON(err == -EMSGSIZE);
566                 kfree_skb(skb);
567                 goto errout;
568         }
569         err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
570 errout:
571         if (err < 0)
572                 rtnl_set_sk_err(ops->nlgroup, err);
573 }
574
575 static void attach_rules(struct list_head *rules, struct net_device *dev)
576 {
577         struct fib_rule *rule;
578
579         list_for_each_entry(rule, rules, list) {
580                 if (rule->ifindex == -1 &&
581                     strcmp(dev->name, rule->ifname) == 0)
582                         rule->ifindex = dev->ifindex;
583         }
584 }
585
586 static void detach_rules(struct list_head *rules, struct net_device *dev)
587 {
588         struct fib_rule *rule;
589
590         list_for_each_entry(rule, rules, list)
591                 if (rule->ifindex == dev->ifindex)
592                         rule->ifindex = -1;
593 }
594
595
596 static int fib_rules_event(struct notifier_block *this, unsigned long event,
597                             void *ptr)
598 {
599         struct net_device *dev = ptr;
600         struct fib_rules_ops *ops;
601
602         if (dev->nd_net != &init_net)
603                 return NOTIFY_DONE;
604
605         ASSERT_RTNL();
606         rcu_read_lock();
607
608         switch (event) {
609         case NETDEV_REGISTER:
610                 list_for_each_entry(ops, &rules_ops, list)
611                         attach_rules(&ops->rules_list, dev);
612                 break;
613
614         case NETDEV_UNREGISTER:
615                 list_for_each_entry(ops, &rules_ops, list)
616                         detach_rules(&ops->rules_list, dev);
617                 break;
618         }
619
620         rcu_read_unlock();
621
622         return NOTIFY_DONE;
623 }
624
625 static struct notifier_block fib_rules_notifier = {
626         .notifier_call = fib_rules_event,
627 };
628
629 static int __init fib_rules_init(void)
630 {
631         rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
632         rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
633         rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
634
635         return register_netdevice_notifier(&fib_rules_notifier);
636 }
637
638 subsys_initcall(fib_rules_init);