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/inet_dscp.h>
20 #include <net/ipv6.h>
21 #include <net/addrconf.h>
22 #include <net/ip6_route.h>
23 #include <net/netlink.h>
24
25 struct fib6_rule {
26 struct fib_rule common;
27 struct rt6key src;
28 struct rt6key dst;
29 dscp_t dscp;
30 u8 dscp_full:1; /* DSCP or TOS selector */
31 };
32
fib6_rule_matchall(const struct fib_rule * rule)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->dscp)
38 return false;
39 return fib_rule_matchall(rule);
40 }
41
fib6_rule_default(const struct fib_rule * rule)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
fib6_rules_dump(struct net * net,struct notifier_block * nb,struct netlink_ext_ack * extack)53 int fib6_rules_dump(struct net *net, struct notifier_block *nb,
54 struct netlink_ext_ack *extack)
55 {
56 return fib_rules_dump(net, nb, AF_INET6, extack);
57 }
58
fib6_rules_seq_read(struct net * net)59 unsigned int fib6_rules_seq_read(struct net *net)
60 {
61 return fib_rules_seq_read(net, AF_INET6);
62 }
63
64 /* called with rcu lock held; no reference taken on fib6_info */
fib6_lookup(struct net * net,int oif,struct flowi6 * fl6,struct fib6_result * res,int flags)65 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
66 struct fib6_result *res, int flags)
67 {
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 .result = res,
75 .flags = FIB_LOOKUP_NOREF,
76 };
77
78 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
79
80 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
81 flowi6_to_flowi(fl6), flags, &arg);
82 } else {
83 err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
84 fl6, res, flags);
85 if (err || res->f6i == net->ipv6.fib6_null_entry)
86 err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
87 oif, fl6, res, flags);
88 }
89
90 return err;
91 }
92
fib6_rule_lookup(struct net * net,struct flowi6 * fl6,const struct sk_buff * skb,int flags,pol_lookup_t lookup)93 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
94 const struct sk_buff *skb,
95 int flags, pol_lookup_t lookup)
96 {
97 if (net->ipv6.fib6_has_custom_rules) {
98 struct fib6_result res = {};
99 struct fib_lookup_arg arg = {
100 .lookup_ptr = lookup,
101 .lookup_data = skb,
102 .result = &res,
103 .flags = FIB_LOOKUP_NOREF,
104 };
105
106 /* update flow if oif or iif point to device enslaved to l3mdev */
107 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
108
109 fib_rules_lookup(net->ipv6.fib6_rules_ops,
110 flowi6_to_flowi(fl6), flags, &arg);
111
112 if (res.rt6)
113 return &res.rt6->dst;
114 } else {
115 struct rt6_info *rt;
116
117 rt = pol_lookup_func(lookup,
118 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_flags(rt, flags);
122 rt = pol_lookup_func(lookup,
123 net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
124 if (rt->dst.error != -EAGAIN)
125 return &rt->dst;
126 ip6_rt_put_flags(rt, flags);
127 }
128
129 if (!(flags & RT6_LOOKUP_F_DST_NOREF))
130 dst_hold(&net->ipv6.ip6_null_entry->dst);
131 return &net->ipv6.ip6_null_entry->dst;
132 }
133
fib6_rule_saddr(struct net * net,struct fib_rule * rule,int flags,struct flowi6 * flp6,const struct net_device * dev)134 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
135 struct flowi6 *flp6, const struct net_device *dev)
136 {
137 struct fib6_rule *r = (struct fib6_rule *)rule;
138
139 /* If we need to find a source address for this traffic,
140 * we check the result if it meets requirement of the rule.
141 */
142 if ((rule->flags & FIB_RULE_FIND_SADDR) &&
143 r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
144 struct in6_addr saddr;
145
146 if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
147 rt6_flags2srcprefs(flags), &saddr))
148 return -EAGAIN;
149
150 if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
151 return -EAGAIN;
152
153 flp6->saddr = saddr;
154 }
155
156 return 0;
157 }
158
fib6_rule_action_alt(struct fib_rule * rule,struct flowi * flp,int flags,struct fib_lookup_arg * arg)159 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
160 int flags, struct fib_lookup_arg *arg)
161 {
162 struct fib6_result *res = arg->result;
163 struct flowi6 *flp6 = &flp->u.ip6;
164 struct net *net = rule->fr_net;
165 struct fib6_table *table;
166 int err, *oif;
167 u32 tb_id;
168
169 switch (rule->action) {
170 case FR_ACT_TO_TBL:
171 break;
172 case FR_ACT_UNREACHABLE:
173 return -ENETUNREACH;
174 case FR_ACT_PROHIBIT:
175 return -EACCES;
176 case FR_ACT_BLACKHOLE:
177 default:
178 return -EINVAL;
179 }
180
181 tb_id = fib_rule_get_table(rule, arg);
182 table = fib6_get_table(net, tb_id);
183 if (!table)
184 return -EAGAIN;
185
186 oif = (int *)arg->lookup_data;
187 err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
188 if (!err && res->f6i != net->ipv6.fib6_null_entry)
189 err = fib6_rule_saddr(net, rule, flags, flp6,
190 res->nh->fib_nh_dev);
191 else
192 err = -EAGAIN;
193
194 return err;
195 }
196
__fib6_rule_action(struct fib_rule * rule,struct flowi * flp,int flags,struct fib_lookup_arg * arg)197 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
198 int flags, struct fib_lookup_arg *arg)
199 {
200 struct fib6_result *res = arg->result;
201 struct flowi6 *flp6 = &flp->u.ip6;
202 struct rt6_info *rt = NULL;
203 struct fib6_table *table;
204 struct net *net = rule->fr_net;
205 pol_lookup_t lookup = arg->lookup_ptr;
206 int err = 0;
207 u32 tb_id;
208
209 switch (rule->action) {
210 case FR_ACT_TO_TBL:
211 break;
212 case FR_ACT_UNREACHABLE:
213 err = -ENETUNREACH;
214 rt = net->ipv6.ip6_null_entry;
215 goto discard_pkt;
216 default:
217 case FR_ACT_BLACKHOLE:
218 err = -EINVAL;
219 rt = net->ipv6.ip6_blk_hole_entry;
220 goto discard_pkt;
221 case FR_ACT_PROHIBIT:
222 err = -EACCES;
223 rt = net->ipv6.ip6_prohibit_entry;
224 goto discard_pkt;
225 }
226
227 tb_id = fib_rule_get_table(rule, arg);
228 table = fib6_get_table(net, tb_id);
229 if (!table) {
230 err = -EAGAIN;
231 goto out;
232 }
233
234 rt = pol_lookup_func(lookup,
235 net, table, flp6, arg->lookup_data, flags);
236 if (rt != net->ipv6.ip6_null_entry) {
237 struct inet6_dev *idev = ip6_dst_idev(&rt->dst);
238
239 if (!idev)
240 goto again;
241 err = fib6_rule_saddr(net, rule, flags, flp6,
242 idev->dev);
243
244 if (err == -EAGAIN)
245 goto again;
246
247 err = rt->dst.error;
248 if (err != -EAGAIN)
249 goto out;
250 }
251 again:
252 ip6_rt_put_flags(rt, flags);
253 err = -EAGAIN;
254 rt = NULL;
255 goto out;
256
257 discard_pkt:
258 if (!(flags & RT6_LOOKUP_F_DST_NOREF))
259 dst_hold(&rt->dst);
260 out:
261 res->rt6 = rt;
262 return err;
263 }
264
fib6_rule_action(struct fib_rule * rule,struct flowi * flp,int flags,struct fib_lookup_arg * arg)265 INDIRECT_CALLABLE_SCOPE int fib6_rule_action(struct fib_rule *rule,
266 struct flowi *flp, int flags,
267 struct fib_lookup_arg *arg)
268 {
269 if (arg->lookup_ptr == fib6_table_lookup)
270 return fib6_rule_action_alt(rule, flp, flags, arg);
271
272 return __fib6_rule_action(rule, flp, flags, arg);
273 }
274
fib6_rule_suppress(struct fib_rule * rule,int flags,struct fib_lookup_arg * arg)275 INDIRECT_CALLABLE_SCOPE bool fib6_rule_suppress(struct fib_rule *rule,
276 int flags,
277 struct fib_lookup_arg *arg)
278 {
279 struct fib6_result *res = arg->result;
280 struct rt6_info *rt = res->rt6;
281 struct net_device *dev = NULL;
282
283 if (!rt)
284 return false;
285
286 if (rt->rt6i_idev)
287 dev = rt->rt6i_idev->dev;
288
289 /* do not accept result if the route does
290 * not meet the required prefix length
291 */
292 if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
293 goto suppress_route;
294
295 /* do not accept result if the route uses a device
296 * belonging to a forbidden interface group
297 */
298 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
299 goto suppress_route;
300
301 return false;
302
303 suppress_route:
304 ip6_rt_put_flags(rt, flags);
305 return true;
306 }
307
fib6_rule_match(struct fib_rule * rule,struct flowi * fl,int flags)308 INDIRECT_CALLABLE_SCOPE int fib6_rule_match(struct fib_rule *rule,
309 struct flowi *fl, int flags)
310 {
311 struct fib6_rule *r = (struct fib6_rule *) rule;
312 struct flowi6 *fl6 = &fl->u.ip6;
313
314 if (r->dst.plen &&
315 !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
316 return 0;
317
318 /*
319 * If FIB_RULE_FIND_SADDR is set and we do not have a
320 * source address for the traffic, we defer check for
321 * source address.
322 */
323 if (r->src.plen) {
324 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
325 if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
326 r->src.plen))
327 return 0;
328 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
329 return 0;
330 }
331
332 if (r->dscp && r->dscp != ip6_dscp(fl6->flowlabel))
333 return 0;
334
335 if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
336 return 0;
337
338 if (fib_rule_port_range_set(&rule->sport_range) &&
339 !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
340 return 0;
341
342 if (fib_rule_port_range_set(&rule->dport_range) &&
343 !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
344 return 0;
345
346 return 1;
347 }
348
fib6_nl2rule_dscp(const struct nlattr * nla,struct fib6_rule * rule6,struct netlink_ext_ack * extack)349 static int fib6_nl2rule_dscp(const struct nlattr *nla, struct fib6_rule *rule6,
350 struct netlink_ext_ack *extack)
351 {
352 if (rule6->dscp) {
353 NL_SET_ERR_MSG(extack, "Cannot specify both TOS and DSCP");
354 return -EINVAL;
355 }
356
357 rule6->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
358 rule6->dscp_full = true;
359
360 return 0;
361 }
362
fib6_rule_configure(struct fib_rule * rule,struct sk_buff * skb,struct fib_rule_hdr * frh,struct nlattr ** tb,struct netlink_ext_ack * extack)363 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
364 struct fib_rule_hdr *frh,
365 struct nlattr **tb,
366 struct netlink_ext_ack *extack)
367 {
368 int err = -EINVAL;
369 struct net *net = sock_net(skb->sk);
370 struct fib6_rule *rule6 = (struct fib6_rule *) rule;
371
372 if (!inet_validate_dscp(frh->tos)) {
373 NL_SET_ERR_MSG(extack,
374 "Invalid dsfield (tos): ECN bits must be 0");
375 goto errout;
376 }
377 rule6->dscp = inet_dsfield_to_dscp(frh->tos);
378
379 if (tb[FRA_DSCP] && fib6_nl2rule_dscp(tb[FRA_DSCP], rule6, extack) < 0)
380 goto errout;
381
382 if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
383 if (rule->table == RT6_TABLE_UNSPEC) {
384 NL_SET_ERR_MSG(extack, "Invalid table");
385 goto errout;
386 }
387
388 if (fib6_new_table(net, rule->table) == NULL) {
389 err = -ENOBUFS;
390 goto errout;
391 }
392 }
393
394 if (frh->src_len)
395 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
396
397 if (frh->dst_len)
398 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
399
400 rule6->src.plen = frh->src_len;
401 rule6->dst.plen = frh->dst_len;
402
403 if (fib_rule_requires_fldissect(rule))
404 net->ipv6.fib6_rules_require_fldissect++;
405
406 net->ipv6.fib6_has_custom_rules = true;
407 err = 0;
408 errout:
409 return err;
410 }
411
fib6_rule_delete(struct fib_rule * rule)412 static int fib6_rule_delete(struct fib_rule *rule)
413 {
414 struct net *net = rule->fr_net;
415
416 if (net->ipv6.fib6_rules_require_fldissect &&
417 fib_rule_requires_fldissect(rule))
418 net->ipv6.fib6_rules_require_fldissect--;
419
420 return 0;
421 }
422
fib6_rule_compare(struct fib_rule * rule,struct fib_rule_hdr * frh,struct nlattr ** tb)423 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
424 struct nlattr **tb)
425 {
426 struct fib6_rule *rule6 = (struct fib6_rule *) rule;
427
428 if (frh->src_len && (rule6->src.plen != frh->src_len))
429 return 0;
430
431 if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
432 return 0;
433
434 if (frh->tos &&
435 (rule6->dscp_full ||
436 inet_dscp_to_dsfield(rule6->dscp) != frh->tos))
437 return 0;
438
439 if (tb[FRA_DSCP]) {
440 dscp_t dscp;
441
442 dscp = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP]) << 2);
443 if (!rule6->dscp_full || rule6->dscp != dscp)
444 return 0;
445 }
446
447 if (frh->src_len &&
448 nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
449 return 0;
450
451 if (frh->dst_len &&
452 nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
453 return 0;
454
455 return 1;
456 }
457
fib6_rule_fill(struct fib_rule * rule,struct sk_buff * skb,struct fib_rule_hdr * frh)458 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
459 struct fib_rule_hdr *frh)
460 {
461 struct fib6_rule *rule6 = (struct fib6_rule *) rule;
462
463 frh->dst_len = rule6->dst.plen;
464 frh->src_len = rule6->src.plen;
465
466 if (rule6->dscp_full) {
467 frh->tos = 0;
468 if (nla_put_u8(skb, FRA_DSCP,
469 inet_dscp_to_dsfield(rule6->dscp) >> 2))
470 goto nla_put_failure;
471 } else {
472 frh->tos = inet_dscp_to_dsfield(rule6->dscp);
473 }
474
475 if ((rule6->dst.plen &&
476 nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
477 (rule6->src.plen &&
478 nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
479 goto nla_put_failure;
480 return 0;
481
482 nla_put_failure:
483 return -ENOBUFS;
484 }
485
fib6_rule_nlmsg_payload(struct fib_rule * rule)486 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
487 {
488 return nla_total_size(16) /* dst */
489 + nla_total_size(16) /* src */
490 + nla_total_size(1); /* dscp */
491 }
492
fib6_rule_flush_cache(struct fib_rules_ops * ops)493 static void fib6_rule_flush_cache(struct fib_rules_ops *ops)
494 {
495 rt_genid_bump_ipv6(ops->fro_net);
496 }
497
498 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
499 .family = AF_INET6,
500 .rule_size = sizeof(struct fib6_rule),
501 .addr_size = sizeof(struct in6_addr),
502 .action = fib6_rule_action,
503 .match = fib6_rule_match,
504 .suppress = fib6_rule_suppress,
505 .configure = fib6_rule_configure,
506 .delete = fib6_rule_delete,
507 .compare = fib6_rule_compare,
508 .fill = fib6_rule_fill,
509 .nlmsg_payload = fib6_rule_nlmsg_payload,
510 .flush_cache = fib6_rule_flush_cache,
511 .nlgroup = RTNLGRP_IPV6_RULE,
512 .owner = THIS_MODULE,
513 .fro_net = &init_net,
514 };
515
fib6_rules_net_init(struct net * net)516 static int __net_init fib6_rules_net_init(struct net *net)
517 {
518 struct fib_rules_ops *ops;
519 int err;
520
521 ops = fib_rules_register(&fib6_rules_ops_template, net);
522 if (IS_ERR(ops))
523 return PTR_ERR(ops);
524
525 err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL);
526 if (err)
527 goto out_fib6_rules_ops;
528
529 err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN);
530 if (err)
531 goto out_fib6_rules_ops;
532
533 net->ipv6.fib6_rules_ops = ops;
534 net->ipv6.fib6_rules_require_fldissect = 0;
535 out:
536 return err;
537
538 out_fib6_rules_ops:
539 fib_rules_unregister(ops);
540 goto out;
541 }
542
fib6_rules_net_exit_batch(struct list_head * net_list)543 static void __net_exit fib6_rules_net_exit_batch(struct list_head *net_list)
544 {
545 struct net *net;
546
547 rtnl_lock();
548 list_for_each_entry(net, net_list, exit_list) {
549 fib_rules_unregister(net->ipv6.fib6_rules_ops);
550 cond_resched();
551 }
552 rtnl_unlock();
553 }
554
555 static struct pernet_operations fib6_rules_net_ops = {
556 .init = fib6_rules_net_init,
557 .exit_batch = fib6_rules_net_exit_batch,
558 };
559
fib6_rules_init(void)560 int __init fib6_rules_init(void)
561 {
562 return register_pernet_subsys(&fib6_rules_net_ops);
563 }
564
565
fib6_rules_cleanup(void)566 void fib6_rules_cleanup(void)
567 {
568 unregister_pernet_subsys(&fib6_rules_net_ops);
569 }
570