xref: /linux/net/ipv6/fib6_rules.c (revision 44f57d78) 
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 
17 #include <net/fib_rules.h>
18 #include <net/ipv6.h>
19 #include <net/addrconf.h>
20 #include <net/ip6_route.h>
21 #include <net/netlink.h>
22 
23 struct fib6_rule {
24 	struct fib_rule		common;
25 	struct rt6key		src;
26 	struct rt6key		dst;
27 	u8			tclass;
28 };
29 
30 static bool fib6_rule_matchall(const struct fib_rule *rule)
31 {
32 	struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
33 
34 	if (r->dst.plen || r->src.plen || r->tclass)
35 		return false;
36 	return fib_rule_matchall(rule);
37 }
38 
39 bool fib6_rule_default(const struct fib_rule *rule)
40 {
41 	if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
42 	    rule->l3mdev)
43 		return false;
44 	if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
45 		return false;
46 	return true;
47 }
48 EXPORT_SYMBOL_GPL(fib6_rule_default);
49 
50 int fib6_rules_dump(struct net *net, struct notifier_block *nb)
51 {
52 	return fib_rules_dump(net, nb, AF_INET6);
53 }
54 
55 unsigned int fib6_rules_seq_read(struct net *net)
56 {
57 	return fib_rules_seq_read(net, AF_INET6);
58 }
59 
60 /* called with rcu lock held; no reference taken on fib6_info */
61 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
62 		struct fib6_result *res, int flags)
63 {
64 	int err;
65 
66 	if (net->ipv6.fib6_has_custom_rules) {
67 		struct fib_lookup_arg arg = {
68 			.lookup_ptr = fib6_table_lookup,
69 			.lookup_data = &oif,
70 			.result = res,
71 			.flags = FIB_LOOKUP_NOREF,
72 		};
73 
74 		l3mdev_update_flow(net, flowi6_to_flowi(fl6));
75 
76 		err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
77 				       flowi6_to_flowi(fl6), flags, &arg);
78 	} else {
79 		err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
80 					fl6, res, flags);
81 		if (err || res->f6i == net->ipv6.fib6_null_entry)
82 			err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
83 						oif, fl6, res, flags);
84 	}
85 
86 	return err;
87 }
88 
89 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
90 				   const struct sk_buff *skb,
91 				   int flags, pol_lookup_t lookup)
92 {
93 	if (net->ipv6.fib6_has_custom_rules) {
94 		struct fib6_result res = {};
95 		struct fib_lookup_arg arg = {
96 			.lookup_ptr = lookup,
97 			.lookup_data = skb,
98 			.result = &res,
99 			.flags = FIB_LOOKUP_NOREF,
100 		};
101 
102 		/* update flow if oif or iif point to device enslaved to l3mdev */
103 		l3mdev_update_flow(net, flowi6_to_flowi(fl6));
104 
105 		fib_rules_lookup(net->ipv6.fib6_rules_ops,
106 				 flowi6_to_flowi(fl6), flags, &arg);
107 
108 		if (res.rt6)
109 			return &res.rt6->dst;
110 	} else {
111 		struct rt6_info *rt;
112 
113 		rt = lookup(net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
114 		if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
115 			return &rt->dst;
116 		ip6_rt_put(rt);
117 		rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
118 		if (rt->dst.error != -EAGAIN)
119 			return &rt->dst;
120 		ip6_rt_put(rt);
121 	}
122 
123 	dst_hold(&net->ipv6.ip6_null_entry->dst);
124 	return &net->ipv6.ip6_null_entry->dst;
125 }
126 
127 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
128 			   struct flowi6 *flp6, const struct net_device *dev)
129 {
130 	struct fib6_rule *r = (struct fib6_rule *)rule;
131 
132 	/* If we need to find a source address for this traffic,
133 	 * we check the result if it meets requirement of the rule.
134 	 */
135 	if ((rule->flags & FIB_RULE_FIND_SADDR) &&
136 	    r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
137 		struct in6_addr saddr;
138 
139 		if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
140 				       rt6_flags2srcprefs(flags), &saddr))
141 			return -EAGAIN;
142 
143 		if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
144 			return -EAGAIN;
145 
146 		flp6->saddr = saddr;
147 	}
148 
149 	return 0;
150 }
151 
152 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
153 				int flags, struct fib_lookup_arg *arg)
154 {
155 	struct fib6_result *res = arg->result;
156 	struct flowi6 *flp6 = &flp->u.ip6;
157 	struct net *net = rule->fr_net;
158 	struct fib6_table *table;
159 	int err, *oif;
160 	u32 tb_id;
161 
162 	switch (rule->action) {
163 	case FR_ACT_TO_TBL:
164 		break;
165 	case FR_ACT_UNREACHABLE:
166 		return -ENETUNREACH;
167 	case FR_ACT_PROHIBIT:
168 		return -EACCES;
169 	case FR_ACT_BLACKHOLE:
170 	default:
171 		return -EINVAL;
172 	}
173 
174 	tb_id = fib_rule_get_table(rule, arg);
175 	table = fib6_get_table(net, tb_id);
176 	if (!table)
177 		return -EAGAIN;
178 
179 	oif = (int *)arg->lookup_data;
180 	err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
181 	if (!err && res->f6i != net->ipv6.fib6_null_entry)
182 		err = fib6_rule_saddr(net, rule, flags, flp6,
183 				      res->nh->fib_nh_dev);
184 	else
185 		err = -EAGAIN;
186 
187 	return err;
188 }
189 
190 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
191 			      int flags, struct fib_lookup_arg *arg)
192 {
193 	struct fib6_result *res = arg->result;
194 	struct flowi6 *flp6 = &flp->u.ip6;
195 	struct rt6_info *rt = NULL;
196 	struct fib6_table *table;
197 	struct net *net = rule->fr_net;
198 	pol_lookup_t lookup = arg->lookup_ptr;
199 	int err = 0;
200 	u32 tb_id;
201 
202 	switch (rule->action) {
203 	case FR_ACT_TO_TBL:
204 		break;
205 	case FR_ACT_UNREACHABLE:
206 		err = -ENETUNREACH;
207 		rt = net->ipv6.ip6_null_entry;
208 		goto discard_pkt;
209 	default:
210 	case FR_ACT_BLACKHOLE:
211 		err = -EINVAL;
212 		rt = net->ipv6.ip6_blk_hole_entry;
213 		goto discard_pkt;
214 	case FR_ACT_PROHIBIT:
215 		err = -EACCES;
216 		rt = net->ipv6.ip6_prohibit_entry;
217 		goto discard_pkt;
218 	}
219 
220 	tb_id = fib_rule_get_table(rule, arg);
221 	table = fib6_get_table(net, tb_id);
222 	if (!table) {
223 		err = -EAGAIN;
224 		goto out;
225 	}
226 
227 	rt = lookup(net, table, flp6, arg->lookup_data, flags);
228 	if (rt != net->ipv6.ip6_null_entry) {
229 		err = fib6_rule_saddr(net, rule, flags, flp6,
230 				      ip6_dst_idev(&rt->dst)->dev);
231 
232 		if (err == -EAGAIN)
233 			goto again;
234 
235 		err = rt->dst.error;
236 		if (err != -EAGAIN)
237 			goto out;
238 	}
239 again:
240 	ip6_rt_put(rt);
241 	err = -EAGAIN;
242 	rt = NULL;
243 	goto out;
244 
245 discard_pkt:
246 	dst_hold(&rt->dst);
247 out:
248 	res->rt6 = rt;
249 	return err;
250 }
251 
252 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
253 			    int flags, struct fib_lookup_arg *arg)
254 {
255 	if (arg->lookup_ptr == fib6_table_lookup)
256 		return fib6_rule_action_alt(rule, flp, flags, arg);
257 
258 	return __fib6_rule_action(rule, flp, flags, arg);
259 }
260 
261 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
262 {
263 	struct fib6_result *res = arg->result;
264 	struct rt6_info *rt = res->rt6;
265 	struct net_device *dev = NULL;
266 
267 	if (!rt)
268 		return false;
269 
270 	if (rt->rt6i_idev)
271 		dev = rt->rt6i_idev->dev;
272 
273 	/* do not accept result if the route does
274 	 * not meet the required prefix length
275 	 */
276 	if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
277 		goto suppress_route;
278 
279 	/* do not accept result if the route uses a device
280 	 * belonging to a forbidden interface group
281 	 */
282 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
283 		goto suppress_route;
284 
285 	return false;
286 
287 suppress_route:
288 	ip6_rt_put(rt);
289 	return true;
290 }
291 
292 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
293 {
294 	struct fib6_rule *r = (struct fib6_rule *) rule;
295 	struct flowi6 *fl6 = &fl->u.ip6;
296 
297 	if (r->dst.plen &&
298 	    !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
299 		return 0;
300 
301 	/*
302 	 * If FIB_RULE_FIND_SADDR is set and we do not have a
303 	 * source address for the traffic, we defer check for
304 	 * source address.
305 	 */
306 	if (r->src.plen) {
307 		if (flags & RT6_LOOKUP_F_HAS_SADDR) {
308 			if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
309 					       r->src.plen))
310 				return 0;
311 		} else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
312 			return 0;
313 	}
314 
315 	if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
316 		return 0;
317 
318 	if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
319 		return 0;
320 
321 	if (fib_rule_port_range_set(&rule->sport_range) &&
322 	    !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
323 		return 0;
324 
325 	if (fib_rule_port_range_set(&rule->dport_range) &&
326 	    !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
327 		return 0;
328 
329 	return 1;
330 }
331 
332 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
333 	FRA_GENERIC_POLICY,
334 };
335 
336 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
337 			       struct fib_rule_hdr *frh,
338 			       struct nlattr **tb,
339 			       struct netlink_ext_ack *extack)
340 {
341 	int err = -EINVAL;
342 	struct net *net = sock_net(skb->sk);
343 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
344 
345 	if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
346 		if (rule->table == RT6_TABLE_UNSPEC) {
347 			NL_SET_ERR_MSG(extack, "Invalid table");
348 			goto errout;
349 		}
350 
351 		if (fib6_new_table(net, rule->table) == NULL) {
352 			err = -ENOBUFS;
353 			goto errout;
354 		}
355 	}
356 
357 	if (frh->src_len)
358 		rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
359 
360 	if (frh->dst_len)
361 		rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
362 
363 	rule6->src.plen = frh->src_len;
364 	rule6->dst.plen = frh->dst_len;
365 	rule6->tclass = frh->tos;
366 
367 	if (fib_rule_requires_fldissect(rule))
368 		net->ipv6.fib6_rules_require_fldissect++;
369 
370 	net->ipv6.fib6_has_custom_rules = true;
371 	err = 0;
372 errout:
373 	return err;
374 }
375 
376 static int fib6_rule_delete(struct fib_rule *rule)
377 {
378 	struct net *net = rule->fr_net;
379 
380 	if (net->ipv6.fib6_rules_require_fldissect &&
381 	    fib_rule_requires_fldissect(rule))
382 		net->ipv6.fib6_rules_require_fldissect--;
383 
384 	return 0;
385 }
386 
387 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
388 			     struct nlattr **tb)
389 {
390 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
391 
392 	if (frh->src_len && (rule6->src.plen != frh->src_len))
393 		return 0;
394 
395 	if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
396 		return 0;
397 
398 	if (frh->tos && (rule6->tclass != frh->tos))
399 		return 0;
400 
401 	if (frh->src_len &&
402 	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
403 		return 0;
404 
405 	if (frh->dst_len &&
406 	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
407 		return 0;
408 
409 	return 1;
410 }
411 
412 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
413 			  struct fib_rule_hdr *frh)
414 {
415 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
416 
417 	frh->dst_len = rule6->dst.plen;
418 	frh->src_len = rule6->src.plen;
419 	frh->tos = rule6->tclass;
420 
421 	if ((rule6->dst.plen &&
422 	     nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
423 	    (rule6->src.plen &&
424 	     nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
425 		goto nla_put_failure;
426 	return 0;
427 
428 nla_put_failure:
429 	return -ENOBUFS;
430 }
431 
432 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
433 {
434 	return nla_total_size(16) /* dst */
435 	       + nla_total_size(16); /* src */
436 }
437 
438 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
439 	.family			= AF_INET6,
440 	.rule_size		= sizeof(struct fib6_rule),
441 	.addr_size		= sizeof(struct in6_addr),
442 	.action			= fib6_rule_action,
443 	.match			= fib6_rule_match,
444 	.suppress		= fib6_rule_suppress,
445 	.configure		= fib6_rule_configure,
446 	.delete			= fib6_rule_delete,
447 	.compare		= fib6_rule_compare,
448 	.fill			= fib6_rule_fill,
449 	.nlmsg_payload		= fib6_rule_nlmsg_payload,
450 	.nlgroup		= RTNLGRP_IPV6_RULE,
451 	.policy			= fib6_rule_policy,
452 	.owner			= THIS_MODULE,
453 	.fro_net		= &init_net,
454 };
455 
456 static int __net_init fib6_rules_net_init(struct net *net)
457 {
458 	struct fib_rules_ops *ops;
459 	int err = -ENOMEM;
460 
461 	ops = fib_rules_register(&fib6_rules_ops_template, net);
462 	if (IS_ERR(ops))
463 		return PTR_ERR(ops);
464 
465 	err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
466 	if (err)
467 		goto out_fib6_rules_ops;
468 
469 	err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
470 	if (err)
471 		goto out_fib6_rules_ops;
472 
473 	net->ipv6.fib6_rules_ops = ops;
474 	net->ipv6.fib6_rules_require_fldissect = 0;
475 out:
476 	return err;
477 
478 out_fib6_rules_ops:
479 	fib_rules_unregister(ops);
480 	goto out;
481 }
482 
483 static void __net_exit fib6_rules_net_exit(struct net *net)
484 {
485 	rtnl_lock();
486 	fib_rules_unregister(net->ipv6.fib6_rules_ops);
487 	rtnl_unlock();
488 }
489 
490 static struct pernet_operations fib6_rules_net_ops = {
491 	.init = fib6_rules_net_init,
492 	.exit = fib6_rules_net_exit,
493 };
494 
495 int __init fib6_rules_init(void)
496 {
497 	return register_pernet_subsys(&fib6_rules_net_ops);
498 }
499 
500 
501 void fib6_rules_cleanup(void)
502 {
503 	unregister_pernet_subsys(&fib6_rules_net_ops);
504 }
505