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Linux/net/ipv6/fib6_rules.c

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  1 /*
  2  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
  3  *
  4  * Copyright (C)2003-2006 Helsinki University of Technology
  5  * Copyright (C)2003-2006 USAGI/WIDE Project
  6  *
  7  *      This program is free software; you can redistribute it and/or
  8  *      modify it under the terms of the GNU General Public License as
  9  *      published by the Free Software Foundation, version 2.
 10  *
 11  * Authors
 12  *      Thomas Graf             <tgraf@suug.ch>
 13  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
 14  */
 15 
 16 #include <linux/netdevice.h>
 17 #include <linux/notifier.h>
 18 #include <linux/export.h>
 19 
 20 #include <net/fib_rules.h>
 21 #include <net/ipv6.h>
 22 #include <net/addrconf.h>
 23 #include <net/ip6_route.h>
 24 #include <net/netlink.h>
 25 
 26 struct fib6_rule {
 27         struct fib_rule         common;
 28         struct rt6key           src;
 29         struct rt6key           dst;
 30         u8                      tclass;
 31 };
 32 
 33 static bool fib6_rule_matchall(const struct fib_rule *rule)
 34 {
 35         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
 36 
 37         if (r->dst.plen || r->src.plen || r->tclass)
 38                 return false;
 39         return fib_rule_matchall(rule);
 40 }
 41 
 42 bool fib6_rule_default(const struct fib_rule *rule)
 43 {
 44         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
 45             rule->l3mdev)
 46                 return false;
 47         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
 48                 return false;
 49         return true;
 50 }
 51 EXPORT_SYMBOL_GPL(fib6_rule_default);
 52 
 53 int fib6_rules_dump(struct net *net, struct notifier_block *nb)
 54 {
 55         return fib_rules_dump(net, nb, AF_INET6);
 56 }
 57 
 58 unsigned int fib6_rules_seq_read(struct net *net)
 59 {
 60         return fib_rules_seq_read(net, AF_INET6);
 61 }
 62 
 63 /* called with rcu lock held; no reference taken on fib6_info */
 64 struct fib6_info *fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 65                               int flags)
 66 {
 67         struct fib6_info *f6i;
 68         int err;
 69 
 70         if (net->ipv6.fib6_has_custom_rules) {
 71                 struct fib_lookup_arg arg = {
 72                         .lookup_ptr = fib6_table_lookup,
 73                         .lookup_data = &oif,
 74                         .flags = FIB_LOOKUP_NOREF,
 75                 };
 76 
 77                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 78 
 79                 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
 80                                        flowi6_to_flowi(fl6), flags, &arg);
 81                 if (err)
 82                         return ERR_PTR(err);
 83 
 84                 f6i = arg.result ? : net->ipv6.fib6_null_entry;
 85         } else {
 86                 f6i = fib6_table_lookup(net, net->ipv6.fib6_local_tbl,
 87                                         oif, fl6, flags);
 88                 if (!f6i || f6i == net->ipv6.fib6_null_entry)
 89                         f6i = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
 90                                                 oif, fl6, flags);
 91         }
 92 
 93         return f6i;
 94 }
 95 
 96 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 97                                    const struct sk_buff *skb,
 98                                    int flags, pol_lookup_t lookup)
 99 {
100         if (net->ipv6.fib6_has_custom_rules) {
101                 struct fib_lookup_arg arg = {
102                         .lookup_ptr = lookup,
103                         .lookup_data = skb,
104                         .flags = FIB_LOOKUP_NOREF,
105                 };
106 
107                 /* update flow if oif or iif point to device enslaved to l3mdev */
108                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
109 
110                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
111                                  flowi6_to_flowi(fl6), flags, &arg);
112 
113                 if (arg.result)
114                         return arg.result;
115         } else {
116                 struct rt6_info *rt;
117 
118                 rt = lookup(net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
119                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
120                         return &rt->dst;
121                 ip6_rt_put(rt);
122                 rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
123                 if (rt->dst.error != -EAGAIN)
124                         return &rt->dst;
125                 ip6_rt_put(rt);
126         }
127 
128         dst_hold(&net->ipv6.ip6_null_entry->dst);
129         return &net->ipv6.ip6_null_entry->dst;
130 }
131 
132 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
133                            struct flowi6 *flp6, const struct net_device *dev)
134 {
135         struct fib6_rule *r = (struct fib6_rule *)rule;
136 
137         /* If we need to find a source address for this traffic,
138          * we check the result if it meets requirement of the rule.
139          */
140         if ((rule->flags & FIB_RULE_FIND_SADDR) &&
141             r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
142                 struct in6_addr saddr;
143 
144                 if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
145                                        rt6_flags2srcprefs(flags), &saddr))
146                         return -EAGAIN;
147 
148                 if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
149                         return -EAGAIN;
150 
151                 flp6->saddr = saddr;
152         }
153 
154         return 0;
155 }
156 
157 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
158                                 int flags, struct fib_lookup_arg *arg)
159 {
160         struct flowi6 *flp6 = &flp->u.ip6;
161         struct net *net = rule->fr_net;
162         struct fib6_table *table;
163         struct fib6_info *f6i;
164         int err = -EAGAIN, *oif;
165         u32 tb_id;
166 
167         switch (rule->action) {
168         case FR_ACT_TO_TBL:
169                 break;
170         case FR_ACT_UNREACHABLE:
171                 return -ENETUNREACH;
172         case FR_ACT_PROHIBIT:
173                 return -EACCES;
174         case FR_ACT_BLACKHOLE:
175         default:
176                 return -EINVAL;
177         }
178 
179         tb_id = fib_rule_get_table(rule, arg);
180         table = fib6_get_table(net, tb_id);
181         if (!table)
182                 return -EAGAIN;
183 
184         oif = (int *)arg->lookup_data;
185         f6i = fib6_table_lookup(net, table, *oif, flp6, flags);
186         if (f6i != net->ipv6.fib6_null_entry) {
187                 err = fib6_rule_saddr(net, rule, flags, flp6,
188                                       fib6_info_nh_dev(f6i));
189 
190                 if (likely(!err))
191                         arg->result = f6i;
192         }
193 
194         return err;
195 }
196 
197 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
198                               int flags, struct fib_lookup_arg *arg)
199 {
200         struct flowi6 *flp6 = &flp->u.ip6;
201         struct rt6_info *rt = NULL;
202         struct fib6_table *table;
203         struct net *net = rule->fr_net;
204         pol_lookup_t lookup = arg->lookup_ptr;
205         int err = 0;
206         u32 tb_id;
207 
208         switch (rule->action) {
209         case FR_ACT_TO_TBL:
210                 break;
211         case FR_ACT_UNREACHABLE:
212                 err = -ENETUNREACH;
213                 rt = net->ipv6.ip6_null_entry;
214                 goto discard_pkt;
215         default:
216         case FR_ACT_BLACKHOLE:
217                 err = -EINVAL;
218                 rt = net->ipv6.ip6_blk_hole_entry;
219                 goto discard_pkt;
220         case FR_ACT_PROHIBIT:
221                 err = -EACCES;
222                 rt = net->ipv6.ip6_prohibit_entry;
223                 goto discard_pkt;
224         }
225 
226         tb_id = fib_rule_get_table(rule, arg);
227         table = fib6_get_table(net, tb_id);
228         if (!table) {
229                 err = -EAGAIN;
230                 goto out;
231         }
232 
233         rt = lookup(net, table, flp6, arg->lookup_data, flags);
234         if (rt != net->ipv6.ip6_null_entry) {
235                 err = fib6_rule_saddr(net, rule, flags, flp6,
236                                       ip6_dst_idev(&rt->dst)->dev);
237 
238                 if (err == -EAGAIN)
239                         goto again;
240 
241                 err = rt->dst.error;
242                 if (err != -EAGAIN)
243                         goto out;
244         }
245 again:
246         ip6_rt_put(rt);
247         err = -EAGAIN;
248         rt = NULL;
249         goto out;
250 
251 discard_pkt:
252         dst_hold(&rt->dst);
253 out:
254         arg->result = rt;
255         return err;
256 }
257 
258 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
259                             int flags, struct fib_lookup_arg *arg)
260 {
261         if (arg->lookup_ptr == fib6_table_lookup)
262                 return fib6_rule_action_alt(rule, flp, flags, arg);
263 
264         return __fib6_rule_action(rule, flp, flags, arg);
265 }
266 
267 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
268 {
269         struct rt6_info *rt = (struct rt6_info *) arg->result;
270         struct net_device *dev = NULL;
271 
272         if (rt->rt6i_idev)
273                 dev = rt->rt6i_idev->dev;
274 
275         /* do not accept result if the route does
276          * not meet the required prefix length
277          */
278         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
279                 goto suppress_route;
280 
281         /* do not accept result if the route uses a device
282          * belonging to a forbidden interface group
283          */
284         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
285                 goto suppress_route;
286 
287         return false;
288 
289 suppress_route:
290         ip6_rt_put(rt);
291         return true;
292 }
293 
294 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
295 {
296         struct fib6_rule *r = (struct fib6_rule *) rule;
297         struct flowi6 *fl6 = &fl->u.ip6;
298 
299         if (r->dst.plen &&
300             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
301                 return 0;
302 
303         /*
304          * If FIB_RULE_FIND_SADDR is set and we do not have a
305          * source address for the traffic, we defer check for
306          * source address.
307          */
308         if (r->src.plen) {
309                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
310                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
311                                                r->src.plen))
312                                 return 0;
313                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
314                         return 0;
315         }
316 
317         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
318                 return 0;
319 
320         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
321                 return 0;
322 
323         if (fib_rule_port_range_set(&rule->sport_range) &&
324             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
325                 return 0;
326 
327         if (fib_rule_port_range_set(&rule->dport_range) &&
328             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
329                 return 0;
330 
331         return 1;
332 }
333 
334 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
335         FRA_GENERIC_POLICY,
336 };
337 
338 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
339                                struct fib_rule_hdr *frh,
340                                struct nlattr **tb,
341                                struct netlink_ext_ack *extack)
342 {
343         int err = -EINVAL;
344         struct net *net = sock_net(skb->sk);
345         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
346 
347         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
348                 if (rule->table == RT6_TABLE_UNSPEC) {
349                         NL_SET_ERR_MSG(extack, "Invalid table");
350                         goto errout;
351                 }
352 
353                 if (fib6_new_table(net, rule->table) == NULL) {
354                         err = -ENOBUFS;
355                         goto errout;
356                 }
357         }
358 
359         if (frh->src_len)
360                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
361 
362         if (frh->dst_len)
363                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
364 
365         rule6->src.plen = frh->src_len;
366         rule6->dst.plen = frh->dst_len;
367         rule6->tclass = frh->tos;
368 
369         if (fib_rule_requires_fldissect(rule))
370                 net->ipv6.fib6_rules_require_fldissect++;
371 
372         net->ipv6.fib6_has_custom_rules = true;
373         err = 0;
374 errout:
375         return err;
376 }
377 
378 static int fib6_rule_delete(struct fib_rule *rule)
379 {
380         struct net *net = rule->fr_net;
381 
382         if (net->ipv6.fib6_rules_require_fldissect &&
383             fib_rule_requires_fldissect(rule))
384                 net->ipv6.fib6_rules_require_fldissect--;
385 
386         return 0;
387 }
388 
389 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
390                              struct nlattr **tb)
391 {
392         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
393 
394         if (frh->src_len && (rule6->src.plen != frh->src_len))
395                 return 0;
396 
397         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
398                 return 0;
399 
400         if (frh->tos && (rule6->tclass != frh->tos))
401                 return 0;
402 
403         if (frh->src_len &&
404             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
405                 return 0;
406 
407         if (frh->dst_len &&
408             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
409                 return 0;
410 
411         return 1;
412 }
413 
414 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
415                           struct fib_rule_hdr *frh)
416 {
417         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
418 
419         frh->dst_len = rule6->dst.plen;
420         frh->src_len = rule6->src.plen;
421         frh->tos = rule6->tclass;
422 
423         if ((rule6->dst.plen &&
424              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
425             (rule6->src.plen &&
426              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
427                 goto nla_put_failure;
428         return 0;
429 
430 nla_put_failure:
431         return -ENOBUFS;
432 }
433 
434 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
435 {
436         return nla_total_size(16) /* dst */
437                + nla_total_size(16); /* src */
438 }
439 
440 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
441         .family                 = AF_INET6,
442         .rule_size              = sizeof(struct fib6_rule),
443         .addr_size              = sizeof(struct in6_addr),
444         .action                 = fib6_rule_action,
445         .match                  = fib6_rule_match,
446         .suppress               = fib6_rule_suppress,
447         .configure              = fib6_rule_configure,
448         .delete                 = fib6_rule_delete,
449         .compare                = fib6_rule_compare,
450         .fill                   = fib6_rule_fill,
451         .nlmsg_payload          = fib6_rule_nlmsg_payload,
452         .nlgroup                = RTNLGRP_IPV6_RULE,
453         .policy                 = fib6_rule_policy,
454         .owner                  = THIS_MODULE,
455         .fro_net                = &init_net,
456 };
457 
458 static int __net_init fib6_rules_net_init(struct net *net)
459 {
460         struct fib_rules_ops *ops;
461         int err = -ENOMEM;
462 
463         ops = fib_rules_register(&fib6_rules_ops_template, net);
464         if (IS_ERR(ops))
465                 return PTR_ERR(ops);
466 
467         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
468         if (err)
469                 goto out_fib6_rules_ops;
470 
471         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
472         if (err)
473                 goto out_fib6_rules_ops;
474 
475         net->ipv6.fib6_rules_ops = ops;
476         net->ipv6.fib6_rules_require_fldissect = 0;
477 out:
478         return err;
479 
480 out_fib6_rules_ops:
481         fib_rules_unregister(ops);
482         goto out;
483 }
484 
485 static void __net_exit fib6_rules_net_exit(struct net *net)
486 {
487         rtnl_lock();
488         fib_rules_unregister(net->ipv6.fib6_rules_ops);
489         rtnl_unlock();
490 }
491 
492 static struct pernet_operations fib6_rules_net_ops = {
493         .init = fib6_rules_net_init,
494         .exit = fib6_rules_net_exit,
495 };
496 
497 int __init fib6_rules_init(void)
498 {
499         return register_pernet_subsys(&fib6_rules_net_ops);
500 }
501 
502 
503 void fib6_rules_cleanup(void)
504 {
505         unregister_pernet_subsys(&fib6_rules_net_ops);
506 }
507 

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