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
28bool 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
78struct 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 */
111void 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
132out:
133	/* Restore the network header back to the ICMP packet */
134	skb->network_header = network_header;
135}
136
137static struct genl_family seg6_genl_family;
138
139static 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
152static 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
222out_unlock:
223	mutex_unlock(&sdata->lock);
224	return err;
225}
226
227#else
228
229static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
230{
231	return -ENOTSUPP;
232}
233
234#endif
235
236static 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
265static 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
292nla_put_failure:
293	rcu_read_unlock();
294free_msg:
295	nlmsg_free(msg);
296	return -ENOMEM;
297}
298
299#ifdef CONFIG_IPV6_SEG6_HMAC
300
301static 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
313static 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
329nla_put_failure:
330	genlmsg_cancel(skb, hdr);
331	return -EMSGSIZE;
332}
333
334static 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
356static 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
367static 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
398done:
399	rhashtable_walk_stop(iter);
400	return ret;
401}
402
403#else
404
405static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
406{
407	return 0;
408}
409
410static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
411{
412	return 0;
413}
414
415static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
416{
417	return -ENOTSUPP;
418}
419
420#endif
421
422static 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
451static 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
463static struct pernet_operations ip6_segments_ops = {
464	.init = seg6_net_init,
465	.exit = seg6_net_exit,
466};
467
468static 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
497static 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
511int __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
543out:
544	return err;
545#ifdef CONFIG_IPV6_SEG6_HMAC
546out_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
553out_unregister_genl:
554	genl_unregister_family(&seg6_genl_family);
555#endif
556out_unregister_pernet:
557	unregister_pernet_subsys(&ip6_segments_ops);
558	goto out;
559}
560
561void seg6_exit(void)
562{
563#ifdef CONFIG_IPV6_SEG6_HMAC
564	seg6_hmac_exit();
565#endif
566#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
567	seg6_iptunnel_exit();
568#endif
569	unregister_pernet_subsys(&ip6_segments_ops);
570	genl_unregister_family(&seg6_genl_family);
571}
572