xref: /openbmc/linux/net/ipv6/seg6.c (revision 2f0754f2) 
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 (hinfo) {
195 		err = seg6_hmac_info_del(net, hmackeyid);
196 		if (err)
197 			goto out_unlock;
198 	}
199 
200 	secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
201 
202 	hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
203 	if (!hinfo) {
204 		err = -ENOMEM;
205 		goto out_unlock;
206 	}
207 
208 	memcpy(hinfo->secret, secret, slen);
209 	hinfo->slen = slen;
210 	hinfo->alg_id = algid;
211 	hinfo->hmackeyid = hmackeyid;
212 
213 	err = seg6_hmac_info_add(net, hmackeyid, hinfo);
214 	if (err)
215 		kfree(hinfo);
216 
217 out_unlock:
218 	mutex_unlock(&sdata->lock);
219 	return err;
220 }
221 
222 #else
223 
224 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
225 {
226 	return -ENOTSUPP;
227 }
228 
229 #endif
230 
231 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
232 {
233 	struct net *net = genl_info_net(info);
234 	struct in6_addr *val, *t_old, *t_new;
235 	struct seg6_pernet_data *sdata;
236 
237 	sdata = seg6_pernet(net);
238 
239 	if (!info->attrs[SEG6_ATTR_DST])
240 		return -EINVAL;
241 
242 	val = nla_data(info->attrs[SEG6_ATTR_DST]);
243 	t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
244 	if (!t_new)
245 		return -ENOMEM;
246 
247 	mutex_lock(&sdata->lock);
248 
249 	t_old = sdata->tun_src;
250 	rcu_assign_pointer(sdata->tun_src, t_new);
251 
252 	mutex_unlock(&sdata->lock);
253 
254 	synchronize_net();
255 	kfree(t_old);
256 
257 	return 0;
258 }
259 
260 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
261 {
262 	struct net *net = genl_info_net(info);
263 	struct in6_addr *tun_src;
264 	struct sk_buff *msg;
265 	void *hdr;
266 
267 	msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
268 	if (!msg)
269 		return -ENOMEM;
270 
271 	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
272 			  &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
273 	if (!hdr)
274 		goto free_msg;
275 
276 	rcu_read_lock();
277 	tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
278 
279 	if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
280 		goto nla_put_failure;
281 
282 	rcu_read_unlock();
283 
284 	genlmsg_end(msg, hdr);
285 	return genlmsg_reply(msg, info);
286 
287 nla_put_failure:
288 	rcu_read_unlock();
289 free_msg:
290 	nlmsg_free(msg);
291 	return -ENOMEM;
292 }
293 
294 #ifdef CONFIG_IPV6_SEG6_HMAC
295 
296 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
297 				 struct sk_buff *msg)
298 {
299 	if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
300 	    nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
301 	    nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
302 	    nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
303 		return -1;
304 
305 	return 0;
306 }
307 
308 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
309 					u32 portid, u32 seq, u32 flags,
310 					struct sk_buff *skb, u8 cmd)
311 {
312 	void *hdr;
313 
314 	hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
315 	if (!hdr)
316 		return -ENOMEM;
317 
318 	if (__seg6_hmac_fill_info(hinfo, skb) < 0)
319 		goto nla_put_failure;
320 
321 	genlmsg_end(skb, hdr);
322 	return 0;
323 
324 nla_put_failure:
325 	genlmsg_cancel(skb, hdr);
326 	return -EMSGSIZE;
327 }
328 
329 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
330 {
331 	struct net *net = sock_net(cb->skb->sk);
332 	struct seg6_pernet_data *sdata;
333 	struct rhashtable_iter *iter;
334 
335 	sdata = seg6_pernet(net);
336 	iter = (struct rhashtable_iter *)cb->args[0];
337 
338 	if (!iter) {
339 		iter = kmalloc(sizeof(*iter), GFP_KERNEL);
340 		if (!iter)
341 			return -ENOMEM;
342 
343 		cb->args[0] = (long)iter;
344 	}
345 
346 	rhashtable_walk_enter(&sdata->hmac_infos, iter);
347 
348 	return 0;
349 }
350 
351 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
352 {
353 	struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
354 
355 	rhashtable_walk_exit(iter);
356 
357 	kfree(iter);
358 
359 	return 0;
360 }
361 
362 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
363 {
364 	struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
365 	struct seg6_hmac_info *hinfo;
366 	int ret;
367 
368 	rhashtable_walk_start(iter);
369 
370 	for (;;) {
371 		hinfo = rhashtable_walk_next(iter);
372 
373 		if (IS_ERR(hinfo)) {
374 			if (PTR_ERR(hinfo) == -EAGAIN)
375 				continue;
376 			ret = PTR_ERR(hinfo);
377 			goto done;
378 		} else if (!hinfo) {
379 			break;
380 		}
381 
382 		ret = __seg6_genl_dumphmac_element(hinfo,
383 						   NETLINK_CB(cb->skb).portid,
384 						   cb->nlh->nlmsg_seq,
385 						   NLM_F_MULTI,
386 						   skb, SEG6_CMD_DUMPHMAC);
387 		if (ret)
388 			goto done;
389 	}
390 
391 	ret = skb->len;
392 
393 done:
394 	rhashtable_walk_stop(iter);
395 	return ret;
396 }
397 
398 #else
399 
400 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
401 {
402 	return 0;
403 }
404 
405 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
406 {
407 	return 0;
408 }
409 
410 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
411 {
412 	return -ENOTSUPP;
413 }
414 
415 #endif
416 
417 static int __net_init seg6_net_init(struct net *net)
418 {
419 	struct seg6_pernet_data *sdata;
420 
421 	sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
422 	if (!sdata)
423 		return -ENOMEM;
424 
425 	mutex_init(&sdata->lock);
426 
427 	sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
428 	if (!sdata->tun_src) {
429 		kfree(sdata);
430 		return -ENOMEM;
431 	}
432 
433 	net->ipv6.seg6_data = sdata;
434 
435 #ifdef CONFIG_IPV6_SEG6_HMAC
436 	if (seg6_hmac_net_init(net)) {
437 		kfree(rcu_dereference_raw(sdata->tun_src));
438 		kfree(sdata);
439 		return -ENOMEM;
440 	}
441 #endif
442 
443 	return 0;
444 }
445 
446 static void __net_exit seg6_net_exit(struct net *net)
447 {
448 	struct seg6_pernet_data *sdata = seg6_pernet(net);
449 
450 #ifdef CONFIG_IPV6_SEG6_HMAC
451 	seg6_hmac_net_exit(net);
452 #endif
453 
454 	kfree(rcu_dereference_raw(sdata->tun_src));
455 	kfree(sdata);
456 }
457 
458 static struct pernet_operations ip6_segments_ops = {
459 	.init = seg6_net_init,
460 	.exit = seg6_net_exit,
461 };
462 
463 static const struct genl_ops seg6_genl_ops[] = {
464 	{
465 		.cmd	= SEG6_CMD_SETHMAC,
466 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
467 		.doit	= seg6_genl_sethmac,
468 		.flags	= GENL_ADMIN_PERM,
469 	},
470 	{
471 		.cmd	= SEG6_CMD_DUMPHMAC,
472 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
473 		.start	= seg6_genl_dumphmac_start,
474 		.dumpit	= seg6_genl_dumphmac,
475 		.done	= seg6_genl_dumphmac_done,
476 		.flags	= GENL_ADMIN_PERM,
477 	},
478 	{
479 		.cmd	= SEG6_CMD_SET_TUNSRC,
480 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
481 		.doit	= seg6_genl_set_tunsrc,
482 		.flags	= GENL_ADMIN_PERM,
483 	},
484 	{
485 		.cmd	= SEG6_CMD_GET_TUNSRC,
486 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
487 		.doit	= seg6_genl_get_tunsrc,
488 		.flags	= GENL_ADMIN_PERM,
489 	},
490 };
491 
492 static struct genl_family seg6_genl_family __ro_after_init = {
493 	.hdrsize	= 0,
494 	.name		= SEG6_GENL_NAME,
495 	.version	= SEG6_GENL_VERSION,
496 	.maxattr	= SEG6_ATTR_MAX,
497 	.policy = seg6_genl_policy,
498 	.netnsok	= true,
499 	.parallel_ops	= true,
500 	.ops		= seg6_genl_ops,
501 	.n_ops		= ARRAY_SIZE(seg6_genl_ops),
502 	.module		= THIS_MODULE,
503 };
504 
505 int __init seg6_init(void)
506 {
507 	int err;
508 
509 	err = genl_register_family(&seg6_genl_family);
510 	if (err)
511 		goto out;
512 
513 	err = register_pernet_subsys(&ip6_segments_ops);
514 	if (err)
515 		goto out_unregister_genl;
516 
517 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
518 	err = seg6_iptunnel_init();
519 	if (err)
520 		goto out_unregister_pernet;
521 
522 	err = seg6_local_init();
523 	if (err)
524 		goto out_unregister_pernet;
525 #endif
526 
527 #ifdef CONFIG_IPV6_SEG6_HMAC
528 	err = seg6_hmac_init();
529 	if (err)
530 		goto out_unregister_iptun;
531 #endif
532 
533 	pr_info("Segment Routing with IPv6\n");
534 
535 out:
536 	return err;
537 #ifdef CONFIG_IPV6_SEG6_HMAC
538 out_unregister_iptun:
539 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
540 	seg6_local_exit();
541 	seg6_iptunnel_exit();
542 #endif
543 #endif
544 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
545 out_unregister_pernet:
546 	unregister_pernet_subsys(&ip6_segments_ops);
547 #endif
548 out_unregister_genl:
549 	genl_unregister_family(&seg6_genl_family);
550 	goto out;
551 }
552 
553 void seg6_exit(void)
554 {
555 #ifdef CONFIG_IPV6_SEG6_HMAC
556 	seg6_hmac_exit();
557 #endif
558 #ifdef CONFIG_IPV6_SEG6_LWTUNNEL
559 	seg6_iptunnel_exit();
560 #endif
561 	unregister_pernet_subsys(&ip6_segments_ops);
562 	genl_unregister_family(&seg6_genl_family);
563 }
564