xref: /openbmc/linux/net/ipv6/seg6.c (revision d8f5ce3c) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  SR-IPv6 implementation
4  *
5  *  Author:
6  *  David Lebrun <david.lebrun@uclouvain.be>
7  */
8 
9 #include <linux/errno.h>
10 #include <linux/types.h>
11 #include <linux/socket.h>
12 #include <linux/net.h>
13 #include <linux/in6.h>
14 #include <linux/slab.h>
15 #include <linux/rhashtable.h>
16 
17 #include <net/ipv6.h>
18 #include <net/protocol.h>
19 
20 #include <net/seg6.h>
21 #include <net/genetlink.h>
22 #include <linux/seg6.h>
23 #include <linux/seg6_genl.h>
24 #ifdef CONFIG_IPV6_SEG6_HMAC
25 #include <net/seg6_hmac.h>
26 #endif
27 
28 bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced)
29 {
30 	unsigned int tlv_offset;
31 	int max_last_entry;
32 	int trailing;
33 
34 	if (srh->type != IPV6_SRCRT_TYPE_4)
35 		return false;
36 
37 	if (((srh->hdrlen + 1) << 3) != len)
38 		return false;
39 
40 	if (!reduced && srh->segments_left > srh->first_segment) {
41 		return false;
42 	} else {
43 		max_last_entry = (srh->hdrlen / 2) - 1;
44 
45 		if (srh->first_segment > max_last_entry)
46 			return false;
47 
48 		if (srh->segments_left > srh->first_segment + 1)
49 			return false;
50 	}
51 
52 	tlv_offset = sizeof(*srh) + ((srh->first_segment + 1) << 4);
53 
54 	trailing = len - tlv_offset;
55 	if (trailing < 0)
56 		return false;
57 
58 	while (trailing) {
59 		struct sr6_tlv *tlv;
60 		unsigned int tlv_len;
61 
62 		if (trailing < sizeof(*tlv))
63 			return false;
64 
65 		tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
66 		tlv_len = sizeof(*tlv) + tlv->len;
67 
68 		trailing -= tlv_len;
69 		if (trailing < 0)
70 			return false;
71 
72 		tlv_offset += tlv_len;
73 	}
74 
75 	return true;
76 }
77 
78 struct ipv6_sr_hdr *seg6_get_srh(struct sk_buff *skb, int flags)
79 {
80 	struct ipv6_sr_hdr *srh;
81 	int len, srhoff = 0;
82 
83 	if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, &flags) < 0)
84 		return NULL;
85 
86 	if (!pskb_may_pull(skb, srhoff + sizeof(*srh)))
87 		return NULL;
88 
89 	srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
90 
91 	len = (srh->hdrlen + 1) << 3;
92 
93 	if (!pskb_may_pull(skb, srhoff + len))
94 		return NULL;
95 
96 	/* note that pskb_may_pull may change pointers in header;
97 	 * for this reason it is necessary to reload them when needed.
98 	 */
99 	srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
100 
101 	if (!seg6_validate_srh(srh, len, true))
102 		return NULL;
103 
104 	return srh;
105 }
106 
107 /* Determine if an ICMP invoking packet contains a segment routing
108  * header.  If it does, extract the offset to the true destination
109  * address, which is in the first segment address.
110  */
111 void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt)
112 {
113 	__u16 network_header = skb->network_header;
114 	struct ipv6_sr_hdr *srh;
115 
116 	/* Update network header to point to the invoking packet
117 	 * inside the ICMP packet, so we can use the seg6_get_srh()
118 	 * helper.
119 	 */
120 	skb_reset_network_header(skb);
121 
122 	srh = seg6_get_srh(skb, 0);
123 	if (!srh)
124 		goto out;
125 
126 	if (srh->type != IPV6_SRCRT_TYPE_4)
127 		goto out;
128 
129 	opt->flags |= IP6SKB_SEG6;
130 	opt->srhoff = (unsigned char *)srh - skb->data;
131 
132 out:
133 	/* Restore the network header back to the ICMP packet */
134 	skb->network_header = network_header;
135 }
136 
137 static struct genl_family seg6_genl_family;
138 
139 static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
140 	[SEG6_ATTR_DST]				= { .type = NLA_BINARY,
141 		.len = sizeof(struct in6_addr) },
142 	[SEG6_ATTR_DSTLEN]			= { .type = NLA_S32, },
143 	[SEG6_ATTR_HMACKEYID]		= { .type = NLA_U32, },
144 	[SEG6_ATTR_SECRET]			= { .type = NLA_BINARY, },
145 	[SEG6_ATTR_SECRETLEN]		= { .type = NLA_U8, },
146 	[SEG6_ATTR_ALGID]			= { .type = NLA_U8, },
147 	[SEG6_ATTR_HMACINFO]		= { .type = NLA_NESTED, },
148 };
149 
150 #ifdef CONFIG_IPV6_SEG6_HMAC
151 
152 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
153 {
154 	struct net *net = genl_info_net(info);
155 	struct seg6_pernet_data *sdata;
156 	struct seg6_hmac_info *hinfo;
157 	u32 hmackeyid;
158 	char *secret;
159 	int err = 0;
160 	u8 algid;
161 	u8 slen;
162 
163 	sdata = seg6_pernet(net);
164 
165 	if (!info->attrs[SEG6_ATTR_HMACKEYID] ||
166 	    !info->attrs[SEG6_ATTR_SECRETLEN] ||
167 	    !info->attrs[SEG6_ATTR_ALGID])
168 		return -EINVAL;
169 
170 	hmackeyid = nla_get_u32(info->attrs[SEG6_ATTR_HMACKEYID]);
171 	slen = nla_get_u8(info->attrs[SEG6_ATTR_SECRETLEN]);
172 	algid = nla_get_u8(info->attrs[SEG6_ATTR_ALGID]);
173 
174 	if (hmackeyid == 0)
175 		return -EINVAL;
176 
177 	if (slen > SEG6_HMAC_SECRET_LEN)
178 		return -EINVAL;
179 
180 	mutex_lock(&sdata->lock);
181 	hinfo = seg6_hmac_info_lookup(net, hmackeyid);
182 
183 	if (!slen) {
184 		err = seg6_hmac_info_del(net, hmackeyid);
185 
186 		goto out_unlock;
187 	}
188 
189 	if (!info->attrs[SEG6_ATTR_SECRET]) {
190 		err = -EINVAL;
191 		goto out_unlock;
192 	}
193 
194 	if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) {
195 		err = -EINVAL;
196 		goto out_unlock;
197 	}
198 
199 	if (hinfo) {
200 		err = seg6_hmac_info_del(net, hmackeyid);
201 		if (err)
202 			goto out_unlock;
203 	}
204 
205 	secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
206 
207 	hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
208 	if (!hinfo) {
209 		err = -ENOMEM;
210 		goto out_unlock;
211 	}
212 
213 	memcpy(hinfo->secret, secret, slen);
214 	hinfo->slen = slen;
215 	hinfo->alg_id = algid;
216 	hinfo->hmackeyid = hmackeyid;
217 
218 	err = seg6_hmac_info_add(net, hmackeyid, hinfo);
219 	if (err)
220 		kfree(hinfo);
221 
222 out_unlock:
223 	mutex_unlock(&sdata->lock);
224 	return err;
225 }
226 
227 #else
228 
229 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
230 {
231 	return -ENOTSUPP;
232 }
233 
234 #endif
235 
236 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
237 {
238 	struct net *net = genl_info_net(info);
239 	struct in6_addr *val, *t_old, *t_new;
240 	struct seg6_pernet_data *sdata;
241 
242 	sdata = seg6_pernet(net);
243 
244 	if (!info->attrs[SEG6_ATTR_DST])
245 		return -EINVAL;
246 
247 	val = nla_data(info->attrs[SEG6_ATTR_DST]);
248 	t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
249 	if (!t_new)
250 		return -ENOMEM;
251 
252 	mutex_lock(&sdata->lock);
253 
254 	t_old = sdata->tun_src;
255 	rcu_assign_pointer(sdata->tun_src, t_new);
256 
257 	mutex_unlock(&sdata->lock);
258 
259 	synchronize_net();
260 	kfree(t_old);
261 
262 	return 0;
263 }
264 
265 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
266 {
267 	struct net *net = genl_info_net(info);
268 	struct in6_addr *tun_src;
269 	struct sk_buff *msg;
270 	void *hdr;
271 
272 	msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
273 	if (!msg)
274 		return -ENOMEM;
275 
276 	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
277 			  &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
278 	if (!hdr)
279 		goto free_msg;
280 
281 	rcu_read_lock();
282 	tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
283 
284 	if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
285 		goto nla_put_failure;
286 
287 	rcu_read_unlock();
288 
289 	genlmsg_end(msg, hdr);
290 	return genlmsg_reply(msg, info);
291 
292 nla_put_failure:
293 	rcu_read_unlock();
294 free_msg:
295 	nlmsg_free(msg);
296 	return -ENOMEM;
297 }
298 
299 #ifdef CONFIG_IPV6_SEG6_HMAC
300 
301 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
302 				 struct sk_buff *msg)
303 {
304 	if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
305 	    nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
306 	    nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
307 	    nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
308 		return -1;
309 
310 	return 0;
311 }
312 
313 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
314 					u32 portid, u32 seq, u32 flags,
315 					struct sk_buff *skb, u8 cmd)
316 {
317 	void *hdr;
318 
319 	hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
320 	if (!hdr)
321 		return -ENOMEM;
322 
323 	if (__seg6_hmac_fill_info(hinfo, skb) < 0)
324 		goto nla_put_failure;
325 
326 	genlmsg_end(skb, hdr);
327 	return 0;
328 
329 nla_put_failure:
330 	genlmsg_cancel(skb, hdr);
331 	return -EMSGSIZE;
332 }
333 
334 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
335 {
336 	struct net *net = sock_net(cb->skb->sk);
337 	struct seg6_pernet_data *sdata;
338 	struct rhashtable_iter *iter;
339 
340 	sdata = seg6_pernet(net);
341 	iter = (struct rhashtable_iter *)cb->args[0];
342 
343 	if (!iter) {
344 		iter = kmalloc(sizeof(*iter), GFP_KERNEL);
345 		if (!iter)
346 			return -ENOMEM;
347 
348 		cb->args[0] = (long)iter;
349 	}
350 
351 	rhashtable_walk_enter(&sdata->hmac_infos, iter);
352 
353 	return 0;
354 }
355 
356 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
357 {
358 	struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
359 
360 	rhashtable_walk_exit(iter);
361 
362 	kfree(iter);
363 
364 	return 0;
365 }
366 
367 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
368 {
369 	struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
370 	struct seg6_hmac_info *hinfo;
371 	int ret;
372 
373 	rhashtable_walk_start(iter);
374 
375 	for (;;) {
376 		hinfo = rhashtable_walk_next(iter);
377 
378 		if (IS_ERR(hinfo)) {
379 			if (PTR_ERR(hinfo) == -EAGAIN)
380 				continue;
381 			ret = PTR_ERR(hinfo);
382 			goto done;
383 		} else if (!hinfo) {
384 			break;
385 		}
386 
387 		ret = __seg6_genl_dumphmac_element(hinfo,
388 						   NETLINK_CB(cb->skb).portid,
389 						   cb->nlh->nlmsg_seq,
390 						   NLM_F_MULTI,
391 						   skb, SEG6_CMD_DUMPHMAC);
392 		if (ret)
393 			goto done;
394 	}
395 
396 	ret = skb->len;
397 
398 done:
399 	rhashtable_walk_stop(iter);
400 	return ret;
401 }
402 
403 #else
404 
405 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
406 {
407 	return 0;
408 }
409 
410 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
411 {
412 	return 0;
413 }
414 
415 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
416 {
417 	return -ENOTSUPP;
418 }
419 
420 #endif
421 
422 static int __net_init seg6_net_init(struct net *net)
423 {
424 	struct seg6_pernet_data *sdata;
425 
426 	sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
427 	if (!sdata)
428 		return -ENOMEM;
429 
430 	mutex_init(&sdata->lock);
431 
432 	sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
433 	if (!sdata->tun_src) {
434 		kfree(sdata);
435 		return -ENOMEM;
436 	}
437 
438 	net->ipv6.seg6_data = sdata;
439 
440 #ifdef CONFIG_IPV6_SEG6_HMAC
441 	if (seg6_hmac_net_init(net)) {
442 		kfree(rcu_dereference_raw(sdata->tun_src));
443 		kfree(sdata);
444 		return -ENOMEM;
445 	}
446 #endif
447 
448 	return 0;
449 }
450 
451 static void __net_exit seg6_net_exit(struct net *net)
452 {
453 	struct seg6_pernet_data *sdata = seg6_pernet(net);
454 
455 #ifdef CONFIG_IPV6_SEG6_HMAC
456 	seg6_hmac_net_exit(net);
457 #endif
458 
459 	kfree(rcu_dereference_raw(sdata->tun_src));
460 	kfree(sdata);
461 }
462 
463 static struct pernet_operations ip6_segments_ops = {
464 	.init = seg6_net_init,
465 	.exit = seg6_net_exit,
466 };
467 
468 static const struct genl_ops seg6_genl_ops[] = {
469 	{
470 		.cmd	= SEG6_CMD_SETHMAC,
471 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
472 		.doit	= seg6_genl_sethmac,
473 		.flags	= GENL_ADMIN_PERM,
474 	},
475 	{
476 		.cmd	= SEG6_CMD_DUMPHMAC,
477 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
478 		.start	= seg6_genl_dumphmac_start,
479 		.dumpit	= seg6_genl_dumphmac,
480 		.done	= seg6_genl_dumphmac_done,
481 		.flags	= GENL_ADMIN_PERM,
482 	},
483 	{
484 		.cmd	= SEG6_CMD_SET_TUNSRC,
485 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
486 		.doit	= seg6_genl_set_tunsrc,
487 		.flags	= GENL_ADMIN_PERM,
488 	},
489 	{
490 		.cmd	= SEG6_CMD_GET_TUNSRC,
491 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
492 		.doit	= seg6_genl_get_tunsrc,
493 		.flags	= GENL_ADMIN_PERM,
494 	},
495 };
496 
497 static struct genl_family seg6_genl_family __ro_after_init = {
498 	.hdrsize	= 0,
499 	.name		= SEG6_GENL_NAME,
500 	.version	= SEG6_GENL_VERSION,
501 	.maxattr	= SEG6_ATTR_MAX,
502 	.policy = seg6_genl_policy,
503 	.netnsok	= true,
504 	.parallel_ops	= true,
505 	.ops		= seg6_genl_ops,
506 	.n_ops		= ARRAY_SIZE(seg6_genl_ops),
507 	.resv_start_op	= SEG6_CMD_GET_TUNSRC + 1,
508 	.module		= THIS_MODULE,
509 };
510 
511 int __init seg6_init(void)
512 {
513 	int err;
514 
515 	err = register_pernet_subsys(&ip6_segments_ops);
516 	if (err)
517 		goto out;
518 
519 	err = genl_register_family(&seg6_genl_family);
520 	if (err)
521 		goto out_unregister_pernet;
522 
523 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
524 	err = seg6_iptunnel_init();
525 	if (err)
526 		goto out_unregister_genl;
527 
528 	err = seg6_local_init();
529 	if (err) {
530 		seg6_iptunnel_exit();
531 		goto out_unregister_genl;
532 	}
533 #endif
534 
535 #ifdef CONFIG_IPV6_SEG6_HMAC
536 	err = seg6_hmac_init();
537 	if (err)
538 		goto out_unregister_iptun;
539 #endif
540 
541 	pr_info("Segment Routing with IPv6\n");
542 
543 out:
544 	return err;
545 #ifdef CONFIG_IPV6_SEG6_HMAC
546 out_unregister_iptun:
547 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
548 	seg6_local_exit();
549 	seg6_iptunnel_exit();
550 #endif
551 #endif
552 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
553 out_unregister_genl:
554 #endif
555 #if IS_ENABLED(CONFIG_IPV6_SEG6_LWTUNNEL) || IS_ENABLED(CONFIG_IPV6_SEG6_HMAC)
556 	genl_unregister_family(&seg6_genl_family);
557 #endif
558 out_unregister_pernet:
559 	unregister_pernet_subsys(&ip6_segments_ops);
560 	goto out;
561 }
562 
563 void seg6_exit(void)
564 {
565 #ifdef CONFIG_IPV6_SEG6_HMAC
566 	seg6_hmac_exit();
567 #endif
568 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
569 	seg6_local_exit();
570 	seg6_iptunnel_exit();
571 #endif
572 	genl_unregister_family(&seg6_genl_family);
573 	unregister_pernet_subsys(&ip6_segments_ops);
574 }
575