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Linux/net/core/fib_rules.c

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  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 #include <net/ip_tunnels.h>
 20 
 21 int fib_default_rule_add(struct fib_rules_ops *ops,
 22                          u32 pref, u32 table, u32 flags)
 23 {
 24         struct fib_rule *r;
 25 
 26         r = kzalloc(ops->rule_size, GFP_KERNEL);
 27         if (r == NULL)
 28                 return -ENOMEM;
 29 
 30         atomic_set(&r->refcnt, 1);
 31         r->action = FR_ACT_TO_TBL;
 32         r->pref = pref;
 33         r->table = table;
 34         r->flags = flags;
 35         r->fr_net = ops->fro_net;
 36 
 37         r->suppress_prefixlen = -1;
 38         r->suppress_ifgroup = -1;
 39 
 40         /* The lock is not required here, the list in unreacheable
 41          * at the moment this function is called */
 42         list_add_tail(&r->list, &ops->rules_list);
 43         return 0;
 44 }
 45 EXPORT_SYMBOL(fib_default_rule_add);
 46 
 47 static u32 fib_default_rule_pref(struct fib_rules_ops *ops)
 48 {
 49         struct list_head *pos;
 50         struct fib_rule *rule;
 51 
 52         if (!list_empty(&ops->rules_list)) {
 53                 pos = ops->rules_list.next;
 54                 if (pos->next != &ops->rules_list) {
 55                         rule = list_entry(pos->next, struct fib_rule, list);
 56                         if (rule->pref)
 57                                 return rule->pref - 1;
 58                 }
 59         }
 60 
 61         return 0;
 62 }
 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         list_add_tail_rcu(&ops->list, &net->rules_ops);
120         err = 0;
121 errout:
122         spin_unlock(&net->rules_mod_lock);
123 
124         return err;
125 }
126 
127 struct fib_rules_ops *
128 fib_rules_register(const struct fib_rules_ops *tmpl, struct net *net)
129 {
130         struct fib_rules_ops *ops;
131         int err;
132 
133         ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
134         if (ops == NULL)
135                 return ERR_PTR(-ENOMEM);
136 
137         INIT_LIST_HEAD(&ops->rules_list);
138         ops->fro_net = net;
139 
140         err = __fib_rules_register(ops);
141         if (err) {
142                 kfree(ops);
143                 ops = ERR_PTR(err);
144         }
145 
146         return ops;
147 }
148 EXPORT_SYMBOL_GPL(fib_rules_register);
149 
150 static void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
151 {
152         struct fib_rule *rule, *tmp;
153 
154         list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
155                 list_del_rcu(&rule->list);
156                 if (ops->delete)
157                         ops->delete(rule);
158                 fib_rule_put(rule);
159         }
160 }
161 
162 void fib_rules_unregister(struct fib_rules_ops *ops)
163 {
164         struct net *net = ops->fro_net;
165 
166         spin_lock(&net->rules_mod_lock);
167         list_del_rcu(&ops->list);
168         spin_unlock(&net->rules_mod_lock);
169 
170         fib_rules_cleanup_ops(ops);
171         kfree_rcu(ops, rcu);
172 }
173 EXPORT_SYMBOL_GPL(fib_rules_unregister);
174 
175 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
176                           struct flowi *fl, int flags,
177                           struct fib_lookup_arg *arg)
178 {
179         int ret = 0;
180 
181         if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
182                 goto out;
183 
184         if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
185                 goto out;
186 
187         if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
188                 goto out;
189 
190         if (rule->tun_id && (rule->tun_id != fl->flowi_tun_key.tun_id))
191                 goto out;
192 
193         if (rule->l3mdev && !l3mdev_fib_rule_match(rule->fr_net, fl, arg))
194                 goto out;
195 
196         ret = ops->match(rule, fl, flags);
197 out:
198         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
199 }
200 
201 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
202                      int flags, struct fib_lookup_arg *arg)
203 {
204         struct fib_rule *rule;
205         int err;
206 
207         rcu_read_lock();
208 
209         list_for_each_entry_rcu(rule, &ops->rules_list, list) {
210 jumped:
211                 if (!fib_rule_match(rule, ops, fl, flags, arg))
212                         continue;
213 
214                 if (rule->action == FR_ACT_GOTO) {
215                         struct fib_rule *target;
216 
217                         target = rcu_dereference(rule->ctarget);
218                         if (target == NULL) {
219                                 continue;
220                         } else {
221                                 rule = target;
222                                 goto jumped;
223                         }
224                 } else if (rule->action == FR_ACT_NOP)
225                         continue;
226                 else
227                         err = ops->action(rule, fl, flags, arg);
228 
229                 if (!err && ops->suppress && ops->suppress(rule, arg))
230                         continue;
231 
232                 if (err != -EAGAIN) {
233                         if ((arg->flags & FIB_LOOKUP_NOREF) ||
234                             likely(atomic_inc_not_zero(&rule->refcnt))) {
235                                 arg->rule = rule;
236                                 goto out;
237                         }
238                         break;
239                 }
240         }
241 
242         err = -ESRCH;
243 out:
244         rcu_read_unlock();
245 
246         return err;
247 }
248 EXPORT_SYMBOL_GPL(fib_rules_lookup);
249 
250 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
251                             struct fib_rules_ops *ops)
252 {
253         int err = -EINVAL;
254 
255         if (frh->src_len)
256                 if (tb[FRA_SRC] == NULL ||
257                     frh->src_len > (ops->addr_size * 8) ||
258                     nla_len(tb[FRA_SRC]) != ops->addr_size)
259                         goto errout;
260 
261         if (frh->dst_len)
262                 if (tb[FRA_DST] == NULL ||
263                     frh->dst_len > (ops->addr_size * 8) ||
264                     nla_len(tb[FRA_DST]) != ops->addr_size)
265                         goto errout;
266 
267         err = 0;
268 errout:
269         return err;
270 }
271 
272 static int rule_exists(struct fib_rules_ops *ops, struct fib_rule_hdr *frh,
273                        struct nlattr **tb, struct fib_rule *rule)
274 {
275         struct fib_rule *r;
276 
277         list_for_each_entry(r, &ops->rules_list, list) {
278                 if (r->action != rule->action)
279                         continue;
280 
281                 if (r->table != rule->table)
282                         continue;
283 
284                 if (r->pref != rule->pref)
285                         continue;
286 
287                 if (memcmp(r->iifname, rule->iifname, IFNAMSIZ))
288                         continue;
289 
290                 if (memcmp(r->oifname, rule->oifname, IFNAMSIZ))
291                         continue;
292 
293                 if (r->mark != rule->mark)
294                         continue;
295 
296                 if (r->mark_mask != rule->mark_mask)
297                         continue;
298 
299                 if (r->tun_id != rule->tun_id)
300                         continue;
301 
302                 if (r->fr_net != rule->fr_net)
303                         continue;
304 
305                 if (r->l3mdev != rule->l3mdev)
306                         continue;
307 
308                 if (!ops->compare(r, frh, tb))
309                         continue;
310                 return 1;
311         }
312         return 0;
313 }
314 
315 int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh)
316 {
317         struct net *net = sock_net(skb->sk);
318         struct fib_rule_hdr *frh = nlmsg_data(nlh);
319         struct fib_rules_ops *ops = NULL;
320         struct fib_rule *rule, *r, *last = NULL;
321         struct nlattr *tb[FRA_MAX+1];
322         int err = -EINVAL, unresolved = 0;
323 
324         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
325                 goto errout;
326 
327         ops = lookup_rules_ops(net, frh->family);
328         if (ops == NULL) {
329                 err = -EAFNOSUPPORT;
330                 goto errout;
331         }
332 
333         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
334         if (err < 0)
335                 goto errout;
336 
337         err = validate_rulemsg(frh, tb, ops);
338         if (err < 0)
339                 goto errout;
340 
341         rule = kzalloc(ops->rule_size, GFP_KERNEL);
342         if (rule == NULL) {
343                 err = -ENOMEM;
344                 goto errout;
345         }
346         rule->fr_net = net;
347 
348         rule->pref = tb[FRA_PRIORITY] ? nla_get_u32(tb[FRA_PRIORITY])
349                                       : fib_default_rule_pref(ops);
350 
351         if (tb[FRA_IIFNAME]) {
352                 struct net_device *dev;
353 
354                 rule->iifindex = -1;
355                 nla_strlcpy(rule->iifname, tb[FRA_IIFNAME], IFNAMSIZ);
356                 dev = __dev_get_by_name(net, rule->iifname);
357                 if (dev)
358                         rule->iifindex = dev->ifindex;
359         }
360 
361         if (tb[FRA_OIFNAME]) {
362                 struct net_device *dev;
363 
364                 rule->oifindex = -1;
365                 nla_strlcpy(rule->oifname, tb[FRA_OIFNAME], IFNAMSIZ);
366                 dev = __dev_get_by_name(net, rule->oifname);
367                 if (dev)
368                         rule->oifindex = dev->ifindex;
369         }
370 
371         if (tb[FRA_FWMARK]) {
372                 rule->mark = nla_get_u32(tb[FRA_FWMARK]);
373                 if (rule->mark)
374                         /* compatibility: if the mark value is non-zero all bits
375                          * are compared unless a mask is explicitly specified.
376                          */
377                         rule->mark_mask = 0xFFFFFFFF;
378         }
379 
380         if (tb[FRA_FWMASK])
381                 rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
382 
383         if (tb[FRA_TUN_ID])
384                 rule->tun_id = nla_get_be64(tb[FRA_TUN_ID]);
385 
386         if (tb[FRA_L3MDEV]) {
387 #ifdef CONFIG_NET_L3_MASTER_DEV
388                 rule->l3mdev = nla_get_u8(tb[FRA_L3MDEV]);
389                 if (rule->l3mdev != 1)
390 #endif
391                         goto errout_free;
392         }
393 
394         rule->action = frh->action;
395         rule->flags = frh->flags;
396         rule->table = frh_get_table(frh, tb);
397         if (tb[FRA_SUPPRESS_PREFIXLEN])
398                 rule->suppress_prefixlen = nla_get_u32(tb[FRA_SUPPRESS_PREFIXLEN]);
399         else
400                 rule->suppress_prefixlen = -1;
401 
402         if (tb[FRA_SUPPRESS_IFGROUP])
403                 rule->suppress_ifgroup = nla_get_u32(tb[FRA_SUPPRESS_IFGROUP]);
404         else
405                 rule->suppress_ifgroup = -1;
406 
407         err = -EINVAL;
408         if (tb[FRA_GOTO]) {
409                 if (rule->action != FR_ACT_GOTO)
410                         goto errout_free;
411 
412                 rule->target = nla_get_u32(tb[FRA_GOTO]);
413                 /* Backward jumps are prohibited to avoid endless loops */
414                 if (rule->target <= rule->pref)
415                         goto errout_free;
416 
417                 list_for_each_entry(r, &ops->rules_list, list) {
418                         if (r->pref == rule->target) {
419                                 RCU_INIT_POINTER(rule->ctarget, r);
420                                 break;
421                         }
422                 }
423 
424                 if (rcu_dereference_protected(rule->ctarget, 1) == NULL)
425                         unresolved = 1;
426         } else if (rule->action == FR_ACT_GOTO)
427                 goto errout_free;
428 
429         if (rule->l3mdev && rule->table)
430                 goto errout_free;
431 
432         if ((nlh->nlmsg_flags & NLM_F_EXCL) &&
433             rule_exists(ops, frh, tb, rule)) {
434                 err = -EEXIST;
435                 goto errout_free;
436         }
437 
438         err = ops->configure(rule, skb, frh, tb);
439         if (err < 0)
440                 goto errout_free;
441 
442         list_for_each_entry(r, &ops->rules_list, list) {
443                 if (r->pref > rule->pref)
444                         break;
445                 last = r;
446         }
447 
448         fib_rule_get(rule);
449 
450         if (last)
451                 list_add_rcu(&rule->list, &last->list);
452         else
453                 list_add_rcu(&rule->list, &ops->rules_list);
454 
455         if (ops->unresolved_rules) {
456                 /*
457                  * There are unresolved goto rules in the list, check if
458                  * any of them are pointing to this new rule.
459                  */
460                 list_for_each_entry(r, &ops->rules_list, list) {
461                         if (r->action == FR_ACT_GOTO &&
462                             r->target == rule->pref &&
463                             rtnl_dereference(r->ctarget) == NULL) {
464                                 rcu_assign_pointer(r->ctarget, rule);
465                                 if (--ops->unresolved_rules == 0)
466                                         break;
467                         }
468                 }
469         }
470 
471         if (rule->action == FR_ACT_GOTO)
472                 ops->nr_goto_rules++;
473 
474         if (unresolved)
475                 ops->unresolved_rules++;
476 
477         if (rule->tun_id)
478                 ip_tunnel_need_metadata();
479 
480         notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).portid);
481         flush_route_cache(ops);
482         rules_ops_put(ops);
483         return 0;
484 
485 errout_free:
486         kfree(rule);
487 errout:
488         rules_ops_put(ops);
489         return err;
490 }
491 EXPORT_SYMBOL_GPL(fib_nl_newrule);
492 
493 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh)
494 {
495         struct net *net = sock_net(skb->sk);
496         struct fib_rule_hdr *frh = nlmsg_data(nlh);
497         struct fib_rules_ops *ops = NULL;
498         struct fib_rule *rule, *tmp;
499         struct nlattr *tb[FRA_MAX+1];
500         int err = -EINVAL;
501 
502         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
503                 goto errout;
504 
505         ops = lookup_rules_ops(net, frh->family);
506         if (ops == NULL) {
507                 err = -EAFNOSUPPORT;
508                 goto errout;
509         }
510 
511         err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
512         if (err < 0)
513                 goto errout;
514 
515         err = validate_rulemsg(frh, tb, ops);
516         if (err < 0)
517                 goto errout;
518 
519         list_for_each_entry(rule, &ops->rules_list, list) {
520                 if (frh->action && (frh->action != rule->action))
521                         continue;
522 
523                 if (frh_get_table(frh, tb) &&
524                     (frh_get_table(frh, tb) != rule->table))
525                         continue;
526 
527                 if (tb[FRA_PRIORITY] &&
528                     (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
529                         continue;
530 
531                 if (tb[FRA_IIFNAME] &&
532                     nla_strcmp(tb[FRA_IIFNAME], rule->iifname))
533                         continue;
534 
535                 if (tb[FRA_OIFNAME] &&
536                     nla_strcmp(tb[FRA_OIFNAME], rule->oifname))
537                         continue;
538 
539                 if (tb[FRA_FWMARK] &&
540                     (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
541                         continue;
542 
543                 if (tb[FRA_FWMASK] &&
544                     (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
545                         continue;
546 
547                 if (tb[FRA_TUN_ID] &&
548                     (rule->tun_id != nla_get_be64(tb[FRA_TUN_ID])))
549                         continue;
550 
551                 if (tb[FRA_L3MDEV] &&
552                     (rule->l3mdev != nla_get_u8(tb[FRA_L3MDEV])))
553                         continue;
554 
555                 if (!ops->compare(rule, frh, tb))
556                         continue;
557 
558                 if (rule->flags & FIB_RULE_PERMANENT) {
559                         err = -EPERM;
560                         goto errout;
561                 }
562 
563                 if (ops->delete) {
564                         err = ops->delete(rule);
565                         if (err)
566                                 goto errout;
567                 }
568 
569                 if (rule->tun_id)
570                         ip_tunnel_unneed_metadata();
571 
572                 list_del_rcu(&rule->list);
573 
574                 if (rule->action == FR_ACT_GOTO) {
575                         ops->nr_goto_rules--;
576                         if (rtnl_dereference(rule->ctarget) == NULL)
577                                 ops->unresolved_rules--;
578                 }
579 
580                 /*
581                  * Check if this rule is a target to any of them. If so,
582                  * disable them. As this operation is eventually very
583                  * expensive, it is only performed if goto rules have
584                  * actually been added.
585                  */
586                 if (ops->nr_goto_rules > 0) {
587                         list_for_each_entry(tmp, &ops->rules_list, list) {
588                                 if (rtnl_dereference(tmp->ctarget) == rule) {
589                                         RCU_INIT_POINTER(tmp->ctarget, NULL);
590                                         ops->unresolved_rules++;
591                                 }
592                         }
593                 }
594 
595                 notify_rule_change(RTM_DELRULE, rule, ops, nlh,
596                                    NETLINK_CB(skb).portid);
597                 fib_rule_put(rule);
598                 flush_route_cache(ops);
599                 rules_ops_put(ops);
600                 return 0;
601         }
602 
603         err = -ENOENT;
604 errout:
605         rules_ops_put(ops);
606         return err;
607 }
608 EXPORT_SYMBOL_GPL(fib_nl_delrule);
609 
610 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
611                                          struct fib_rule *rule)
612 {
613         size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
614                          + nla_total_size(IFNAMSIZ) /* FRA_IIFNAME */
615                          + nla_total_size(IFNAMSIZ) /* FRA_OIFNAME */
616                          + nla_total_size(4) /* FRA_PRIORITY */
617                          + nla_total_size(4) /* FRA_TABLE */
618                          + nla_total_size(4) /* FRA_SUPPRESS_PREFIXLEN */
619                          + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
620                          + nla_total_size(4) /* FRA_FWMARK */
621                          + nla_total_size(4) /* FRA_FWMASK */
622                          + nla_total_size_64bit(8); /* FRA_TUN_ID */
623 
624         if (ops->nlmsg_payload)
625                 payload += ops->nlmsg_payload(rule);
626 
627         return payload;
628 }
629 
630 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
631                             u32 pid, u32 seq, int type, int flags,
632                             struct fib_rules_ops *ops)
633 {
634         struct nlmsghdr *nlh;
635         struct fib_rule_hdr *frh;
636 
637         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
638         if (nlh == NULL)
639                 return -EMSGSIZE;
640 
641         frh = nlmsg_data(nlh);
642         frh->family = ops->family;
643         frh->table = rule->table;
644         if (nla_put_u32(skb, FRA_TABLE, rule->table))
645                 goto nla_put_failure;
646         if (nla_put_u32(skb, FRA_SUPPRESS_PREFIXLEN, rule->suppress_prefixlen))
647                 goto nla_put_failure;
648         frh->res1 = 0;
649         frh->res2 = 0;
650         frh->action = rule->action;
651         frh->flags = rule->flags;
652 
653         if (rule->action == FR_ACT_GOTO &&
654             rcu_access_pointer(rule->ctarget) == NULL)
655                 frh->flags |= FIB_RULE_UNRESOLVED;
656 
657         if (rule->iifname[0]) {
658                 if (nla_put_string(skb, FRA_IIFNAME, rule->iifname))
659                         goto nla_put_failure;
660                 if (rule->iifindex == -1)
661                         frh->flags |= FIB_RULE_IIF_DETACHED;
662         }
663 
664         if (rule->oifname[0]) {
665                 if (nla_put_string(skb, FRA_OIFNAME, rule->oifname))
666                         goto nla_put_failure;
667                 if (rule->oifindex == -1)
668                         frh->flags |= FIB_RULE_OIF_DETACHED;
669         }
670 
671         if ((rule->pref &&
672              nla_put_u32(skb, FRA_PRIORITY, rule->pref)) ||
673             (rule->mark &&
674              nla_put_u32(skb, FRA_FWMARK, rule->mark)) ||
675             ((rule->mark_mask || rule->mark) &&
676              nla_put_u32(skb, FRA_FWMASK, rule->mark_mask)) ||
677             (rule->target &&
678              nla_put_u32(skb, FRA_GOTO, rule->target)) ||
679             (rule->tun_id &&
680              nla_put_be64(skb, FRA_TUN_ID, rule->tun_id, FRA_PAD)) ||
681             (rule->l3mdev &&
682              nla_put_u8(skb, FRA_L3MDEV, rule->l3mdev)))
683                 goto nla_put_failure;
684 
685         if (rule->suppress_ifgroup != -1) {
686                 if (nla_put_u32(skb, FRA_SUPPRESS_IFGROUP, rule->suppress_ifgroup))
687                         goto nla_put_failure;
688         }
689 
690         if (ops->fill(rule, skb, frh) < 0)
691                 goto nla_put_failure;
692 
693         nlmsg_end(skb, nlh);
694         return 0;
695 
696 nla_put_failure:
697         nlmsg_cancel(skb, nlh);
698         return -EMSGSIZE;
699 }
700 
701 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
702                       struct fib_rules_ops *ops)
703 {
704         int idx = 0;
705         struct fib_rule *rule;
706         int err = 0;
707 
708         rcu_read_lock();
709         list_for_each_entry_rcu(rule, &ops->rules_list, list) {
710                 if (idx < cb->args[1])
711                         goto skip;
712 
713                 err = fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).portid,
714                                        cb->nlh->nlmsg_seq, RTM_NEWRULE,
715                                        NLM_F_MULTI, ops);
716                 if (err)
717                         break;
718 skip:
719                 idx++;
720         }
721         rcu_read_unlock();
722         cb->args[1] = idx;
723         rules_ops_put(ops);
724 
725         return err;
726 }
727 
728 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
729 {
730         struct net *net = sock_net(skb->sk);
731         struct fib_rules_ops *ops;
732         int idx = 0, family;
733 
734         family = rtnl_msg_family(cb->nlh);
735         if (family != AF_UNSPEC) {
736                 /* Protocol specific dump request */
737                 ops = lookup_rules_ops(net, family);
738                 if (ops == NULL)
739                         return -EAFNOSUPPORT;
740 
741                 dump_rules(skb, cb, ops);
742 
743                 return skb->len;
744         }
745 
746         rcu_read_lock();
747         list_for_each_entry_rcu(ops, &net->rules_ops, list) {
748                 if (idx < cb->args[0] || !try_module_get(ops->owner))
749                         goto skip;
750 
751                 if (dump_rules(skb, cb, ops) < 0)
752                         break;
753 
754                 cb->args[1] = 0;
755 skip:
756                 idx++;
757         }
758         rcu_read_unlock();
759         cb->args[0] = idx;
760 
761         return skb->len;
762 }
763 
764 static void notify_rule_change(int event, struct fib_rule *rule,
765                                struct fib_rules_ops *ops, struct nlmsghdr *nlh,
766                                u32 pid)
767 {
768         struct net *net;
769         struct sk_buff *skb;
770         int err = -ENOBUFS;
771 
772         net = ops->fro_net;
773         skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
774         if (skb == NULL)
775                 goto errout;
776 
777         err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
778         if (err < 0) {
779                 /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
780                 WARN_ON(err == -EMSGSIZE);
781                 kfree_skb(skb);
782                 goto errout;
783         }
784 
785         rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
786         return;
787 errout:
788         if (err < 0)
789                 rtnl_set_sk_err(net, ops->nlgroup, err);
790 }
791 
792 static void attach_rules(struct list_head *rules, struct net_device *dev)
793 {
794         struct fib_rule *rule;
795 
796         list_for_each_entry(rule, rules, list) {
797                 if (rule->iifindex == -1 &&
798                     strcmp(dev->name, rule->iifname) == 0)
799                         rule->iifindex = dev->ifindex;
800                 if (rule->oifindex == -1 &&
801                     strcmp(dev->name, rule->oifname) == 0)
802                         rule->oifindex = dev->ifindex;
803         }
804 }
805 
806 static void detach_rules(struct list_head *rules, struct net_device *dev)
807 {
808         struct fib_rule *rule;
809 
810         list_for_each_entry(rule, rules, list) {
811                 if (rule->iifindex == dev->ifindex)
812                         rule->iifindex = -1;
813                 if (rule->oifindex == dev->ifindex)
814                         rule->oifindex = -1;
815         }
816 }
817 
818 
819 static int fib_rules_event(struct notifier_block *this, unsigned long event,
820                            void *ptr)
821 {
822         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
823         struct net *net = dev_net(dev);
824         struct fib_rules_ops *ops;
825 
826         ASSERT_RTNL();
827 
828         switch (event) {
829         case NETDEV_REGISTER:
830                 list_for_each_entry(ops, &net->rules_ops, list)
831                         attach_rules(&ops->rules_list, dev);
832                 break;
833 
834         case NETDEV_CHANGENAME:
835                 list_for_each_entry(ops, &net->rules_ops, list) {
836                         detach_rules(&ops->rules_list, dev);
837                         attach_rules(&ops->rules_list, dev);
838                 }
839                 break;
840 
841         case NETDEV_UNREGISTER:
842                 list_for_each_entry(ops, &net->rules_ops, list)
843                         detach_rules(&ops->rules_list, dev);
844                 break;
845         }
846 
847         return NOTIFY_DONE;
848 }
849 
850 static struct notifier_block fib_rules_notifier = {
851         .notifier_call = fib_rules_event,
852 };
853 
854 static int __net_init fib_rules_net_init(struct net *net)
855 {
856         INIT_LIST_HEAD(&net->rules_ops);
857         spin_lock_init(&net->rules_mod_lock);
858         return 0;
859 }
860 
861 static struct pernet_operations fib_rules_net_ops = {
862         .init = fib_rules_net_init,
863 };
864 
865 static int __init fib_rules_init(void)
866 {
867         int err;
868         rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL, NULL);
869         rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL, NULL);
870         rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule, NULL);
871 
872         err = register_pernet_subsys(&fib_rules_net_ops);
873         if (err < 0)
874                 goto fail;
875 
876         err = register_netdevice_notifier(&fib_rules_notifier);
877         if (err < 0)
878                 goto fail_unregister;
879 
880         return 0;
881 
882 fail_unregister:
883         unregister_pernet_subsys(&fib_rules_net_ops);
884 fail:
885         rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
886         rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
887         rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
888         return err;
889 }
890 
891 subsys_initcall(fib_rules_init);
892 

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