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 #include <net/seg6_hmac.h>
25
26 bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced)
27 {
28 unsigned int tlv_offset;
29 int max_last_entry;
30 int trailing;
31
32 if (srh->type != IPV6_SRCRT_TYPE_4)
33 return false;
34
35 if (((srh->hdrlen + 1) << 3) != len)
36 return false;
37
38 if (!reduced && srh->segments_left > srh->first_segment) {
39 return false;
40 } else {
41 max_last_entry = (srh->hdrlen / 2) - 1;
42
43 if (srh->first_segment > max_last_entry)
44 return false;
45
46 if (srh->segments_left > srh->first_segment + 1)
47 return false;
48 }
49
50 tlv_offset = sizeof(*srh) + ((srh->first_segment + 1) << 4);
51
52 trailing = len - tlv_offset;
53 if (trailing < 0)
54 return false;
55
56 while (trailing) {
57 struct sr6_tlv *tlv;
58 unsigned int tlv_len;
59
60 if (trailing < sizeof(*tlv))
61 return false;
62
63 tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
64 tlv_len = sizeof(*tlv) + tlv->len;
65
66 trailing -= tlv_len;
67 if (trailing < 0)
68 return false;
69
70 tlv_offset += tlv_len;
71 }
72
73 return true;
74 }
75
76 struct ipv6_sr_hdr *seg6_get_srh(struct sk_buff *skb, int flags)
77 {
78 struct ipv6_sr_hdr *srh;
79 int len, srhoff = 0;
80
81 if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, &flags) < 0)
82 return NULL;
83
84 if (!pskb_may_pull(skb, srhoff + sizeof(*srh)))
85 return NULL;
86
87 srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
88
89 len = (srh->hdrlen + 1) << 3;
90
91 if (!pskb_may_pull(skb, srhoff + len))
92 return NULL;
93
94 /* note that pskb_may_pull may change pointers in header;
95 * for this reason it is necessary to reload them when needed.
96 */
97 srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
98
99 if (!seg6_validate_srh(srh, len, true))
100 return NULL;
101
102 return srh;
103 }
104
105 /* Determine if an ICMP invoking packet contains a segment routing
106 * header. If it does, extract the offset to the true destination
107 * address, which is in the first segment address.
108 */
109 void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt)
110 {
111 __u16 network_header = skb->network_header;
112 struct ipv6_sr_hdr *srh;
113
114 /* Update network header to point to the invoking packet
115 * inside the ICMP packet, so we can use the seg6_get_srh()
116 * helper.
117 */
118 skb_reset_network_header(skb);
119
120 srh = seg6_get_srh(skb, 0);
121 if (!srh)
122 goto out;
123
124 if (srh->type != IPV6_SRCRT_TYPE_4)
125 goto out;
126
127 opt->flags |= IP6SKB_SEG6;
128 opt->srhoff = (unsigned char *)srh - skb->data;
129
130 out:
131 /* Restore the network header back to the ICMP packet */
132 skb->network_header = network_header;
133 }
134
135 static struct genl_family seg6_genl_family;
136
137 static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
138 [SEG6_ATTR_DST] = { .type = NLA_BINARY,
139 .len = sizeof(struct in6_addr) },
140 [SEG6_ATTR_DSTLEN] = { .type = NLA_S32, },
141 [SEG6_ATTR_HMACKEYID] = { .type = NLA_U32, },
142 [SEG6_ATTR_SECRET] = { .type = NLA_BINARY, },
143 [SEG6_ATTR_SECRETLEN] = { .type = NLA_U8, },
144 [SEG6_ATTR_ALGID] = { .type = NLA_U8, },
145 [SEG6_ATTR_HMACINFO] = { .type = NLA_NESTED, },
146 };
147
148 #ifdef CONFIG_IPV6_SEG6_HMAC
149
150 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
151 {
152 struct net *net = genl_info_net(info);
153 struct seg6_pernet_data *sdata;
154 struct seg6_hmac_info *hinfo;
155 u32 hmackeyid;
156 char *secret;
157 int err = 0;
158 u8 algid;
159 u8 slen;
160
161 sdata = seg6_pernet(net);
162
163 if (!info->attrs[SEG6_ATTR_HMACKEYID] ||
164 !info->attrs[SEG6_ATTR_SECRETLEN] ||
165 !info->attrs[SEG6_ATTR_ALGID])
166 return -EINVAL;
167
168 hmackeyid = nla_get_u32(info->attrs[SEG6_ATTR_HMACKEYID]);
169 slen = nla_get_u8(info->attrs[SEG6_ATTR_SECRETLEN]);
170 algid = nla_get_u8(info->attrs[SEG6_ATTR_ALGID]);
171
172 if (hmackeyid == 0)
173 return -EINVAL;
174
175 if (slen > SEG6_HMAC_SECRET_LEN)
176 return -EINVAL;
177
178 mutex_lock(&sdata->lock);
179 hinfo = seg6_hmac_info_lookup(net, hmackeyid);
180
181 if (!slen) {
182 err = seg6_hmac_info_del(net, hmackeyid);
183
184 goto out_unlock;
185 }
186
187 if (!info->attrs[SEG6_ATTR_SECRET]) {
188 err = -EINVAL;
189 goto out_unlock;
190 }
191
192 if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) {
193 err = -EINVAL;
194 goto out_unlock;
195 }
196
197 if (hinfo) {
198 err = seg6_hmac_info_del(net, hmackeyid);
199 if (err)
200 goto out_unlock;
201 }
202
203 secret = (char *)nla_data(info->attrs[SEG6_ATTR_SECRET]);
204
205 hinfo = kzalloc(sizeof(*hinfo), GFP_KERNEL);
206 if (!hinfo) {
207 err = -ENOMEM;
208 goto out_unlock;
209 }
210
211 memcpy(hinfo->secret, secret, slen);
212 hinfo->slen = slen;
213 hinfo->alg_id = algid;
214 hinfo->hmackeyid = hmackeyid;
215
216 err = seg6_hmac_info_add(net, hmackeyid, hinfo);
217 if (err)
218 kfree(hinfo);
219
220 out_unlock:
221 mutex_unlock(&sdata->lock);
222 return err;
223 }
224
225 #else
226
227 static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info)
228 {
229 return -ENOTSUPP;
230 }
231
232 #endif
233
234 static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info)
235 {
236 struct net *net = genl_info_net(info);
237 struct in6_addr *val, *t_old, *t_new;
238 struct seg6_pernet_data *sdata;
239
240 sdata = seg6_pernet(net);
241
242 if (!info->attrs[SEG6_ATTR_DST])
243 return -EINVAL;
244
245 val = nla_data(info->attrs[SEG6_ATTR_DST]);
246 t_new = kmemdup(val, sizeof(*val), GFP_KERNEL);
247 if (!t_new)
248 return -ENOMEM;
249
250 mutex_lock(&sdata->lock);
251
252 t_old = sdata->tun_src;
253 rcu_assign_pointer(sdata->tun_src, t_new);
254
255 mutex_unlock(&sdata->lock);
256
257 synchronize_net();
258 kfree(t_old);
259
260 return 0;
261 }
262
263 static int seg6_genl_get_tunsrc(struct sk_buff *skb, struct genl_info *info)
264 {
265 struct net *net = genl_info_net(info);
266 struct in6_addr *tun_src;
267 struct sk_buff *msg;
268 void *hdr;
269
270 msg = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
271 if (!msg)
272 return -ENOMEM;
273
274 hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
275 &seg6_genl_family, 0, SEG6_CMD_GET_TUNSRC);
276 if (!hdr)
277 goto free_msg;
278
279 rcu_read_lock();
280 tun_src = rcu_dereference(seg6_pernet(net)->tun_src);
281
282 if (nla_put(msg, SEG6_ATTR_DST, sizeof(struct in6_addr), tun_src))
283 goto nla_put_failure;
284
285 rcu_read_unlock();
286
287 genlmsg_end(msg, hdr);
288 return genlmsg_reply(msg, info);
289
290 nla_put_failure:
291 rcu_read_unlock();
292 free_msg:
293 nlmsg_free(msg);
294 return -ENOMEM;
295 }
296
297 #ifdef CONFIG_IPV6_SEG6_HMAC
298
299 static int __seg6_hmac_fill_info(struct seg6_hmac_info *hinfo,
300 struct sk_buff *msg)
301 {
302 if (nla_put_u32(msg, SEG6_ATTR_HMACKEYID, hinfo->hmackeyid) ||
303 nla_put_u8(msg, SEG6_ATTR_SECRETLEN, hinfo->slen) ||
304 nla_put(msg, SEG6_ATTR_SECRET, hinfo->slen, hinfo->secret) ||
305 nla_put_u8(msg, SEG6_ATTR_ALGID, hinfo->alg_id))
306 return -1;
307
308 return 0;
309 }
310
311 static int __seg6_genl_dumphmac_element(struct seg6_hmac_info *hinfo,
312 u32 portid, u32 seq, u32 flags,
313 struct sk_buff *skb, u8 cmd)
314 {
315 void *hdr;
316
317 hdr = genlmsg_put(skb, portid, seq, &seg6_genl_family, flags, cmd);
318 if (!hdr)
319 return -ENOMEM;
320
321 if (__seg6_hmac_fill_info(hinfo, skb) < 0)
322 goto nla_put_failure;
323
324 genlmsg_end(skb, hdr);
325 return 0;
326
327 nla_put_failure:
328 genlmsg_cancel(skb, hdr);
329 return -EMSGSIZE;
330 }
331
332 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
333 {
334 struct net *net = sock_net(cb->skb->sk);
335 struct seg6_pernet_data *sdata;
336 struct rhashtable_iter *iter;
337
338 sdata = seg6_pernet(net);
339 iter = (struct rhashtable_iter *)cb->args[0];
340
341 if (!iter) {
342 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
343 if (!iter)
344 return -ENOMEM;
345
346 cb->args[0] = (long)iter;
347 }
348
349 rhashtable_walk_enter(&sdata->hmac_infos, iter);
350
351 return 0;
352 }
353
354 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
355 {
356 struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
357
358 rhashtable_walk_exit(iter);
359
360 kfree(iter);
361
362 return 0;
363 }
364
365 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
366 {
367 struct rhashtable_iter *iter = (struct rhashtable_iter *)cb->args[0];
368 struct seg6_hmac_info *hinfo;
369 int ret;
370
371 rhashtable_walk_start(iter);
372
373 for (;;) {
374 hinfo = rhashtable_walk_next(iter);
375
376 if (IS_ERR(hinfo)) {
377 if (PTR_ERR(hinfo) == -EAGAIN)
378 continue;
379 ret = PTR_ERR(hinfo);
380 goto done;
381 } else if (!hinfo) {
382 break;
383 }
384
385 ret = __seg6_genl_dumphmac_element(hinfo,
386 NETLINK_CB(cb->skb).portid,
387 cb->nlh->nlmsg_seq,
388 NLM_F_MULTI,
389 skb, SEG6_CMD_DUMPHMAC);
390 if (ret)
391 goto done;
392 }
393
394 ret = skb->len;
395
396 done:
397 rhashtable_walk_stop(iter);
398 return ret;
399 }
400
401 #else
402
403 static int seg6_genl_dumphmac_start(struct netlink_callback *cb)
404 {
405 return 0;
406 }
407
408 static int seg6_genl_dumphmac_done(struct netlink_callback *cb)
409 {
410 return 0;
411 }
412
413 static int seg6_genl_dumphmac(struct sk_buff *skb, struct netlink_callback *cb)
414 {
415 return -ENOTSUPP;
416 }
417
418 #endif
419
420 static int __net_init seg6_net_init(struct net *net)
421 {
422 struct seg6_pernet_data *sdata;
423
424 sdata = kzalloc(sizeof(*sdata), GFP_KERNEL);
425 if (!sdata)
426 return -ENOMEM;
427
428 mutex_init(&sdata->lock);
429
430 sdata->tun_src = kzalloc(sizeof(*sdata->tun_src), GFP_KERNEL);
431 if (!sdata->tun_src) {
432 kfree(sdata);
433 return -ENOMEM;
434 }
435
436 net->ipv6.seg6_data = sdata;
437
438 if (seg6_hmac_net_init(net)) {
439 kfree(rcu_dereference_raw(sdata->tun_src));
440 kfree(sdata);
441 return -ENOMEM;
442 }
443
444 return 0;
445 }
446
447 static void __net_exit seg6_net_exit(struct net *net)
448 {
449 struct seg6_pernet_data *sdata = seg6_pernet(net);
450
451 seg6_hmac_net_exit(net);
452
453 kfree(rcu_dereference_raw(sdata->tun_src));
454 kfree(sdata);
455 }
456
457 static struct pernet_operations ip6_segments_ops = {
458 .init = seg6_net_init,
459 .exit = seg6_net_exit,
460 };
461
462 static const struct genl_ops seg6_genl_ops[] = {
463 {
464 .cmd = SEG6_CMD_SETHMAC,
465 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
466 .doit = seg6_genl_sethmac,
467 .flags = GENL_ADMIN_PERM,
468 },
469 {
470 .cmd = SEG6_CMD_DUMPHMAC,
471 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
472 .start = seg6_genl_dumphmac_start,
473 .dumpit = seg6_genl_dumphmac,
474 .done = seg6_genl_dumphmac_done,
475 .flags = GENL_ADMIN_PERM,
476 },
477 {
478 .cmd = SEG6_CMD_SET_TUNSRC,
479 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
480 .doit = seg6_genl_set_tunsrc,
481 .flags = GENL_ADMIN_PERM,
482 },
483 {
484 .cmd = SEG6_CMD_GET_TUNSRC,
485 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
486 .doit = seg6_genl_get_tunsrc,
487 .flags = GENL_ADMIN_PERM,
488 },
489 };
490
491 static struct genl_family seg6_genl_family __ro_after_init = {
492 .hdrsize = 0,
493 .name = SEG6_GENL_NAME,
494 .version = SEG6_GENL_VERSION,
495 .maxattr = SEG6_ATTR_MAX,
496 .policy = seg6_genl_policy,
497 .netnsok = true,
498 .parallel_ops = true,
499 .ops = seg6_genl_ops,
500 .n_ops = ARRAY_SIZE(seg6_genl_ops),
501 .resv_start_op = SEG6_CMD_GET_TUNSRC + 1,
502 .module = THIS_MODULE,
503 };
504
505 int __init seg6_init(void)
506 {
507 int err;
508
509 err = register_pernet_subsys(&ip6_segments_ops);
510 if (err)
511 goto out;
512
513 err = genl_register_family(&seg6_genl_family);
514 if (err)
515 goto out_unregister_pernet;
516
517 err = seg6_iptunnel_init();
518 if (err)
519 goto out_unregister_genl;
520
521 err = seg6_local_init();
522 if (err)
523 goto out_unregister_iptun;
524
525 err = seg6_hmac_init();
526 if (err)
527 goto out_unregister_seg6;
528
529 pr_info("Segment Routing with IPv6\n");
530
531 out:
532 return err;
533 out_unregister_seg6:
534 seg6_local_exit();
535 out_unregister_iptun:
536 seg6_iptunnel_exit();
537 out_unregister_genl:
538 genl_unregister_family(&seg6_genl_family);
539 out_unregister_pernet:
540 unregister_pernet_subsys(&ip6_segments_ops);
541 goto out;
542 }
543
544 void seg6_exit(void)
545 {
546 seg6_hmac_exit();
547 seg6_local_exit();
548 seg6_iptunnel_exit();
549 genl_unregister_family(&seg6_genl_family);
550 unregister_pernet_subsys(&ip6_segments_ops);
551 }
552
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