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Linux/net/ipv6/fib6_rules.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
  4  *
  5  * Copyright (C)2003-2006 Helsinki University of Technology
  6  * Copyright (C)2003-2006 USAGI/WIDE Project
  7  *
  8  * Authors
  9  *      Thomas Graf             <tgraf@suug.ch>
 10  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
 11  */
 12 
 13 #include <linux/netdevice.h>
 14 #include <linux/notifier.h>
 15 #include <linux/export.h>
 16 #include <linux/indirect_call_wrapper.h>
 17 
 18 #include <net/fib_rules.h>
 19 #include <net/ipv6.h>
 20 #include <net/addrconf.h>
 21 #include <net/ip6_route.h>
 22 #include <net/netlink.h>
 23 
 24 struct fib6_rule {
 25         struct fib_rule         common;
 26         struct rt6key           src;
 27         struct rt6key           dst;
 28         u8                      tclass;
 29 };
 30 
 31 static bool fib6_rule_matchall(const struct fib_rule *rule)
 32 {
 33         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
 34 
 35         if (r->dst.plen || r->src.plen || r->tclass)
 36                 return false;
 37         return fib_rule_matchall(rule);
 38 }
 39 
 40 bool fib6_rule_default(const struct fib_rule *rule)
 41 {
 42         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
 43             rule->l3mdev)
 44                 return false;
 45         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
 46                 return false;
 47         return true;
 48 }
 49 EXPORT_SYMBOL_GPL(fib6_rule_default);
 50 
 51 int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 52                     struct netlink_ext_ack *extack)
 53 {
 54         return fib_rules_dump(net, nb, AF_INET6, extack);
 55 }
 56 
 57 unsigned int fib6_rules_seq_read(struct net *net)
 58 {
 59         return fib_rules_seq_read(net, AF_INET6);
 60 }
 61 
 62 /* called with rcu lock held; no reference taken on fib6_info */
 63 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 64                 struct fib6_result *res, int flags)
 65 {
 66         int err;
 67 
 68         if (net->ipv6.fib6_has_custom_rules) {
 69                 struct fib_lookup_arg arg = {
 70                         .lookup_ptr = fib6_table_lookup,
 71                         .lookup_data = &oif,
 72                         .result = res,
 73                         .flags = FIB_LOOKUP_NOREF,
 74                 };
 75 
 76                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 77 
 78                 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
 79                                        flowi6_to_flowi(fl6), flags, &arg);
 80         } else {
 81                 err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
 82                                         fl6, res, flags);
 83                 if (err || res->f6i == net->ipv6.fib6_null_entry)
 84                         err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
 85                                                 oif, fl6, res, flags);
 86         }
 87 
 88         return err;
 89 }
 90 
 91 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 92                                    const struct sk_buff *skb,
 93                                    int flags, pol_lookup_t lookup)
 94 {
 95         if (net->ipv6.fib6_has_custom_rules) {
 96                 struct fib6_result res = {};
 97                 struct fib_lookup_arg arg = {
 98                         .lookup_ptr = lookup,
 99                         .lookup_data = skb,
100                         .result = &res,
101                         .flags = FIB_LOOKUP_NOREF,
102                 };
103 
104                 /* update flow if oif or iif point to device enslaved to l3mdev */
105                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
106 
107                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
108                                  flowi6_to_flowi(fl6), flags, &arg);
109 
110                 if (res.rt6)
111                         return &res.rt6->dst;
112         } else {
113                 struct rt6_info *rt;
114 
115                 rt = pol_lookup_func(lookup,
116                              net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
117                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
118                         return &rt->dst;
119                 ip6_rt_put_flags(rt, flags);
120                 rt = pol_lookup_func(lookup,
121                              net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
122                 if (rt->dst.error != -EAGAIN)
123                         return &rt->dst;
124                 ip6_rt_put_flags(rt, flags);
125         }
126 
127         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
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 fib6_result *res = arg->result;
161         struct flowi6 *flp6 = &flp->u.ip6;
162         struct net *net = rule->fr_net;
163         struct fib6_table *table;
164         int err, *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         err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
186         if (!err && res->f6i != net->ipv6.fib6_null_entry)
187                 err = fib6_rule_saddr(net, rule, flags, flp6,
188                                       res->nh->fib_nh_dev);
189         else
190                 err = -EAGAIN;
191 
192         return err;
193 }
194 
195 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
196                               int flags, struct fib_lookup_arg *arg)
197 {
198         struct fib6_result *res = arg->result;
199         struct flowi6 *flp6 = &flp->u.ip6;
200         struct rt6_info *rt = NULL;
201         struct fib6_table *table;
202         struct net *net = rule->fr_net;
203         pol_lookup_t lookup = arg->lookup_ptr;
204         int err = 0;
205         u32 tb_id;
206 
207         switch (rule->action) {
208         case FR_ACT_TO_TBL:
209                 break;
210         case FR_ACT_UNREACHABLE:
211                 err = -ENETUNREACH;
212                 rt = net->ipv6.ip6_null_entry;
213                 goto discard_pkt;
214         default:
215         case FR_ACT_BLACKHOLE:
216                 err = -EINVAL;
217                 rt = net->ipv6.ip6_blk_hole_entry;
218                 goto discard_pkt;
219         case FR_ACT_PROHIBIT:
220                 err = -EACCES;
221                 rt = net->ipv6.ip6_prohibit_entry;
222                 goto discard_pkt;
223         }
224 
225         tb_id = fib_rule_get_table(rule, arg);
226         table = fib6_get_table(net, tb_id);
227         if (!table) {
228                 err = -EAGAIN;
229                 goto out;
230         }
231 
232         rt = pol_lookup_func(lookup,
233                              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_flags(rt, flags);
247         err = -EAGAIN;
248         rt = NULL;
249         goto out;
250 
251 discard_pkt:
252         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
253                 dst_hold(&rt->dst);
254 out:
255         res->rt6 = rt;
256         return err;
257 }
258 
259 INDIRECT_CALLABLE_SCOPE int fib6_rule_action(struct fib_rule *rule,
260                                              struct flowi *flp, int flags,
261                                              struct fib_lookup_arg *arg)
262 {
263         if (arg->lookup_ptr == fib6_table_lookup)
264                 return fib6_rule_action_alt(rule, flp, flags, arg);
265 
266         return __fib6_rule_action(rule, flp, flags, arg);
267 }
268 
269 INDIRECT_CALLABLE_SCOPE bool fib6_rule_suppress(struct fib_rule *rule,
270                                                 struct fib_lookup_arg *arg)
271 {
272         struct fib6_result *res = arg->result;
273         struct rt6_info *rt = res->rt6;
274         struct net_device *dev = NULL;
275 
276         if (!rt)
277                 return false;
278 
279         if (rt->rt6i_idev)
280                 dev = rt->rt6i_idev->dev;
281 
282         /* do not accept result if the route does
283          * not meet the required prefix length
284          */
285         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
286                 goto suppress_route;
287 
288         /* do not accept result if the route uses a device
289          * belonging to a forbidden interface group
290          */
291         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
292                 goto suppress_route;
293 
294         return false;
295 
296 suppress_route:
297         if (!(arg->flags & FIB_LOOKUP_NOREF))
298                 ip6_rt_put(rt);
299         return true;
300 }
301 
302 INDIRECT_CALLABLE_SCOPE int fib6_rule_match(struct fib_rule *rule,
303                                             struct flowi *fl, int flags)
304 {
305         struct fib6_rule *r = (struct fib6_rule *) rule;
306         struct flowi6 *fl6 = &fl->u.ip6;
307 
308         if (r->dst.plen &&
309             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
310                 return 0;
311 
312         /*
313          * If FIB_RULE_FIND_SADDR is set and we do not have a
314          * source address for the traffic, we defer check for
315          * source address.
316          */
317         if (r->src.plen) {
318                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
319                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
320                                                r->src.plen))
321                                 return 0;
322                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
323                         return 0;
324         }
325 
326         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
327                 return 0;
328 
329         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
330                 return 0;
331 
332         if (fib_rule_port_range_set(&rule->sport_range) &&
333             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
334                 return 0;
335 
336         if (fib_rule_port_range_set(&rule->dport_range) &&
337             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
338                 return 0;
339 
340         return 1;
341 }
342 
343 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
344         FRA_GENERIC_POLICY,
345 };
346 
347 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
348                                struct fib_rule_hdr *frh,
349                                struct nlattr **tb,
350                                struct netlink_ext_ack *extack)
351 {
352         int err = -EINVAL;
353         struct net *net = sock_net(skb->sk);
354         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
355 
356         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
357                 if (rule->table == RT6_TABLE_UNSPEC) {
358                         NL_SET_ERR_MSG(extack, "Invalid table");
359                         goto errout;
360                 }
361 
362                 if (fib6_new_table(net, rule->table) == NULL) {
363                         err = -ENOBUFS;
364                         goto errout;
365                 }
366         }
367 
368         if (frh->src_len)
369                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
370 
371         if (frh->dst_len)
372                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
373 
374         rule6->src.plen = frh->src_len;
375         rule6->dst.plen = frh->dst_len;
376         rule6->tclass = frh->tos;
377 
378         if (fib_rule_requires_fldissect(rule))
379                 net->ipv6.fib6_rules_require_fldissect++;
380 
381         net->ipv6.fib6_has_custom_rules = true;
382         err = 0;
383 errout:
384         return err;
385 }
386 
387 static int fib6_rule_delete(struct fib_rule *rule)
388 {
389         struct net *net = rule->fr_net;
390 
391         if (net->ipv6.fib6_rules_require_fldissect &&
392             fib_rule_requires_fldissect(rule))
393                 net->ipv6.fib6_rules_require_fldissect--;
394 
395         return 0;
396 }
397 
398 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
399                              struct nlattr **tb)
400 {
401         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
402 
403         if (frh->src_len && (rule6->src.plen != frh->src_len))
404                 return 0;
405 
406         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
407                 return 0;
408 
409         if (frh->tos && (rule6->tclass != frh->tos))
410                 return 0;
411 
412         if (frh->src_len &&
413             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
414                 return 0;
415 
416         if (frh->dst_len &&
417             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
418                 return 0;
419 
420         return 1;
421 }
422 
423 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
424                           struct fib_rule_hdr *frh)
425 {
426         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
427 
428         frh->dst_len = rule6->dst.plen;
429         frh->src_len = rule6->src.plen;
430         frh->tos = rule6->tclass;
431 
432         if ((rule6->dst.plen &&
433              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
434             (rule6->src.plen &&
435              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
436                 goto nla_put_failure;
437         return 0;
438 
439 nla_put_failure:
440         return -ENOBUFS;
441 }
442 
443 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
444 {
445         return nla_total_size(16) /* dst */
446                + nla_total_size(16); /* src */
447 }
448 
449 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
450         .family                 = AF_INET6,
451         .rule_size              = sizeof(struct fib6_rule),
452         .addr_size              = sizeof(struct in6_addr),
453         .action                 = fib6_rule_action,
454         .match                  = fib6_rule_match,
455         .suppress               = fib6_rule_suppress,
456         .configure              = fib6_rule_configure,
457         .delete                 = fib6_rule_delete,
458         .compare                = fib6_rule_compare,
459         .fill                   = fib6_rule_fill,
460         .nlmsg_payload          = fib6_rule_nlmsg_payload,
461         .nlgroup                = RTNLGRP_IPV6_RULE,
462         .policy                 = fib6_rule_policy,
463         .owner                  = THIS_MODULE,
464         .fro_net                = &init_net,
465 };
466 
467 static int __net_init fib6_rules_net_init(struct net *net)
468 {
469         struct fib_rules_ops *ops;
470         int err = -ENOMEM;
471 
472         ops = fib_rules_register(&fib6_rules_ops_template, net);
473         if (IS_ERR(ops))
474                 return PTR_ERR(ops);
475 
476         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
477         if (err)
478                 goto out_fib6_rules_ops;
479 
480         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
481         if (err)
482                 goto out_fib6_rules_ops;
483 
484         net->ipv6.fib6_rules_ops = ops;
485         net->ipv6.fib6_rules_require_fldissect = 0;
486 out:
487         return err;
488 
489 out_fib6_rules_ops:
490         fib_rules_unregister(ops);
491         goto out;
492 }
493 
494 static void __net_exit fib6_rules_net_exit(struct net *net)
495 {
496         rtnl_lock();
497         fib_rules_unregister(net->ipv6.fib6_rules_ops);
498         rtnl_unlock();
499 }
500 
501 static struct pernet_operations fib6_rules_net_ops = {
502         .init = fib6_rules_net_init,
503         .exit = fib6_rules_net_exit,
504 };
505 
506 int __init fib6_rules_init(void)
507 {
508         return register_pernet_subsys(&fib6_rules_net_ops);
509 }
510 
511 
512 void fib6_rules_cleanup(void)
513 {
514         unregister_pernet_subsys(&fib6_rules_net_ops);
515 }
516 

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