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1/* SCTP kernel implementation
2 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
3 *
4 * This file is part of the SCTP kernel implementation
5 *
6 * This SCTP implementation is free software;
7 * you can redistribute it and/or modify it under the terms of
8 * the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
10 * any later version.
11 *
12 * This SCTP implementation is distributed in the hope that it
13 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
14 * ************************
15 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16 * See the GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with GNU CC; see the file COPYING. If not, see
20 * <http://www.gnu.org/licenses/>.
21 *
22 * Please send any bug reports or fixes you make to the
23 * email address(es):
24 * lksctp developers <linux-sctp@vger.kernel.org>
25 *
26 * Written or modified by:
27 * Vlad Yasevich <vladislav.yasevich@hp.com>
28 */
29
30#include <linux/slab.h>
31#include <linux/types.h>
32#include <linux/crypto.h>
33#include <linux/scatterlist.h>
34#include <net/sctp/sctp.h>
35#include <net/sctp/auth.h>
36
37static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
38 {
39 /* id 0 is reserved. as all 0 */
40 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
41 },
42 {
43 .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
44 .hmac_name = "hmac(sha1)",
45 .hmac_len = SCTP_SHA1_SIG_SIZE,
46 },
47 {
48 /* id 2 is reserved as well */
49 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
50 },
51#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
52 {
53 .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
54 .hmac_name = "hmac(sha256)",
55 .hmac_len = SCTP_SHA256_SIG_SIZE,
56 }
57#endif
58};
59
60
61void sctp_auth_key_put(struct sctp_auth_bytes *key)
62{
63 if (!key)
64 return;
65
66 if (atomic_dec_and_test(&key->refcnt)) {
67 kzfree(key);
68 SCTP_DBG_OBJCNT_DEC(keys);
69 }
70}
71
72/* Create a new key structure of a given length */
73static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
74{
75 struct sctp_auth_bytes *key;
76
77 /* Verify that we are not going to overflow INT_MAX */
78 if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
79 return NULL;
80
81 /* Allocate the shared key */
82 key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
83 if (!key)
84 return NULL;
85
86 key->len = key_len;
87 atomic_set(&key->refcnt, 1);
88 SCTP_DBG_OBJCNT_INC(keys);
89
90 return key;
91}
92
93/* Create a new shared key container with a give key id */
94struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
95{
96 struct sctp_shared_key *new;
97
98 /* Allocate the shared key container */
99 new = kzalloc(sizeof(struct sctp_shared_key), gfp);
100 if (!new)
101 return NULL;
102
103 INIT_LIST_HEAD(&new->key_list);
104 new->key_id = key_id;
105
106 return new;
107}
108
109/* Free the shared key structure */
110static void sctp_auth_shkey_free(struct sctp_shared_key *sh_key)
111{
112 BUG_ON(!list_empty(&sh_key->key_list));
113 sctp_auth_key_put(sh_key->key);
114 sh_key->key = NULL;
115 kfree(sh_key);
116}
117
118/* Destroy the entire key list. This is done during the
119 * associon and endpoint free process.
120 */
121void sctp_auth_destroy_keys(struct list_head *keys)
122{
123 struct sctp_shared_key *ep_key;
124 struct sctp_shared_key *tmp;
125
126 if (list_empty(keys))
127 return;
128
129 key_for_each_safe(ep_key, tmp, keys) {
130 list_del_init(&ep_key->key_list);
131 sctp_auth_shkey_free(ep_key);
132 }
133}
134
135/* Compare two byte vectors as numbers. Return values
136 * are:
137 * 0 - vectors are equal
138 * < 0 - vector 1 is smaller than vector2
139 * > 0 - vector 1 is greater than vector2
140 *
141 * Algorithm is:
142 * This is performed by selecting the numerically smaller key vector...
143 * If the key vectors are equal as numbers but differ in length ...
144 * the shorter vector is considered smaller
145 *
146 * Examples (with small values):
147 * 000123456789 > 123456789 (first number is longer)
148 * 000123456789 < 234567891 (second number is larger numerically)
149 * 123456789 > 2345678 (first number is both larger & longer)
150 */
151static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
152 struct sctp_auth_bytes *vector2)
153{
154 int diff;
155 int i;
156 const __u8 *longer;
157
158 diff = vector1->len - vector2->len;
159 if (diff) {
160 longer = (diff > 0) ? vector1->data : vector2->data;
161
162 /* Check to see if the longer number is
163 * lead-zero padded. If it is not, it
164 * is automatically larger numerically.
165 */
166 for (i = 0; i < abs(diff); i++) {
167 if (longer[i] != 0)
168 return diff;
169 }
170 }
171
172 /* lengths are the same, compare numbers */
173 return memcmp(vector1->data, vector2->data, vector1->len);
174}
175
176/*
177 * Create a key vector as described in SCTP-AUTH, Section 6.1
178 * The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
179 * parameter sent by each endpoint are concatenated as byte vectors.
180 * These parameters include the parameter type, parameter length, and
181 * the parameter value, but padding is omitted; all padding MUST be
182 * removed from this concatenation before proceeding with further
183 * computation of keys. Parameters which were not sent are simply
184 * omitted from the concatenation process. The resulting two vectors
185 * are called the two key vectors.
186 */
187static struct sctp_auth_bytes *sctp_auth_make_key_vector(
188 sctp_random_param_t *random,
189 sctp_chunks_param_t *chunks,
190 sctp_hmac_algo_param_t *hmacs,
191 gfp_t gfp)
192{
193 struct sctp_auth_bytes *new;
194 __u32 len;
195 __u32 offset = 0;
196 __u16 random_len, hmacs_len, chunks_len = 0;
197
198 random_len = ntohs(random->param_hdr.length);
199 hmacs_len = ntohs(hmacs->param_hdr.length);
200 if (chunks)
201 chunks_len = ntohs(chunks->param_hdr.length);
202
203 len = random_len + hmacs_len + chunks_len;
204
205 new = sctp_auth_create_key(len, gfp);
206 if (!new)
207 return NULL;
208
209 memcpy(new->data, random, random_len);
210 offset += random_len;
211
212 if (chunks) {
213 memcpy(new->data + offset, chunks, chunks_len);
214 offset += chunks_len;
215 }
216
217 memcpy(new->data + offset, hmacs, hmacs_len);
218
219 return new;
220}
221
222
223/* Make a key vector based on our local parameters */
224static struct sctp_auth_bytes *sctp_auth_make_local_vector(
225 const struct sctp_association *asoc,
226 gfp_t gfp)
227{
228 return sctp_auth_make_key_vector(
229 (sctp_random_param_t *)asoc->c.auth_random,
230 (sctp_chunks_param_t *)asoc->c.auth_chunks,
231 (sctp_hmac_algo_param_t *)asoc->c.auth_hmacs,
232 gfp);
233}
234
235/* Make a key vector based on peer's parameters */
236static struct sctp_auth_bytes *sctp_auth_make_peer_vector(
237 const struct sctp_association *asoc,
238 gfp_t gfp)
239{
240 return sctp_auth_make_key_vector(asoc->peer.peer_random,
241 asoc->peer.peer_chunks,
242 asoc->peer.peer_hmacs,
243 gfp);
244}
245
246
247/* Set the value of the association shared key base on the parameters
248 * given. The algorithm is:
249 * From the endpoint pair shared keys and the key vectors the
250 * association shared keys are computed. This is performed by selecting
251 * the numerically smaller key vector and concatenating it to the
252 * endpoint pair shared key, and then concatenating the numerically
253 * larger key vector to that. The result of the concatenation is the
254 * association shared key.
255 */
256static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
257 struct sctp_shared_key *ep_key,
258 struct sctp_auth_bytes *first_vector,
259 struct sctp_auth_bytes *last_vector,
260 gfp_t gfp)
261{
262 struct sctp_auth_bytes *secret;
263 __u32 offset = 0;
264 __u32 auth_len;
265
266 auth_len = first_vector->len + last_vector->len;
267 if (ep_key->key)
268 auth_len += ep_key->key->len;
269
270 secret = sctp_auth_create_key(auth_len, gfp);
271 if (!secret)
272 return NULL;
273
274 if (ep_key->key) {
275 memcpy(secret->data, ep_key->key->data, ep_key->key->len);
276 offset += ep_key->key->len;
277 }
278
279 memcpy(secret->data + offset, first_vector->data, first_vector->len);
280 offset += first_vector->len;
281
282 memcpy(secret->data + offset, last_vector->data, last_vector->len);
283
284 return secret;
285}
286
287/* Create an association shared key. Follow the algorithm
288 * described in SCTP-AUTH, Section 6.1
289 */
290static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
291 const struct sctp_association *asoc,
292 struct sctp_shared_key *ep_key,
293 gfp_t gfp)
294{
295 struct sctp_auth_bytes *local_key_vector;
296 struct sctp_auth_bytes *peer_key_vector;
297 struct sctp_auth_bytes *first_vector,
298 *last_vector;
299 struct sctp_auth_bytes *secret = NULL;
300 int cmp;
301
302
303 /* Now we need to build the key vectors
304 * SCTP-AUTH , Section 6.1
305 * The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
306 * parameter sent by each endpoint are concatenated as byte vectors.
307 * These parameters include the parameter type, parameter length, and
308 * the parameter value, but padding is omitted; all padding MUST be
309 * removed from this concatenation before proceeding with further
310 * computation of keys. Parameters which were not sent are simply
311 * omitted from the concatenation process. The resulting two vectors
312 * are called the two key vectors.
313 */
314
315 local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
316 peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
317
318 if (!peer_key_vector || !local_key_vector)
319 goto out;
320
321 /* Figure out the order in which the key_vectors will be
322 * added to the endpoint shared key.
323 * SCTP-AUTH, Section 6.1:
324 * This is performed by selecting the numerically smaller key
325 * vector and concatenating it to the endpoint pair shared
326 * key, and then concatenating the numerically larger key
327 * vector to that. If the key vectors are equal as numbers
328 * but differ in length, then the concatenation order is the
329 * endpoint shared key, followed by the shorter key vector,
330 * followed by the longer key vector. Otherwise, the key
331 * vectors are identical, and may be concatenated to the
332 * endpoint pair key in any order.
333 */
334 cmp = sctp_auth_compare_vectors(local_key_vector,
335 peer_key_vector);
336 if (cmp < 0) {
337 first_vector = local_key_vector;
338 last_vector = peer_key_vector;
339 } else {
340 first_vector = peer_key_vector;
341 last_vector = local_key_vector;
342 }
343
344 secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
345 gfp);
346out:
347 sctp_auth_key_put(local_key_vector);
348 sctp_auth_key_put(peer_key_vector);
349
350 return secret;
351}
352
353/*
354 * Populate the association overlay list with the list
355 * from the endpoint.
356 */
357int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
358 struct sctp_association *asoc,
359 gfp_t gfp)
360{
361 struct sctp_shared_key *sh_key;
362 struct sctp_shared_key *new;
363
364 BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
365
366 key_for_each(sh_key, &ep->endpoint_shared_keys) {
367 new = sctp_auth_shkey_create(sh_key->key_id, gfp);
368 if (!new)
369 goto nomem;
370
371 new->key = sh_key->key;
372 sctp_auth_key_hold(new->key);
373 list_add(&new->key_list, &asoc->endpoint_shared_keys);
374 }
375
376 return 0;
377
378nomem:
379 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
380 return -ENOMEM;
381}
382
383
384/* Public interface to creat the association shared key.
385 * See code above for the algorithm.
386 */
387int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
388{
389 struct sctp_auth_bytes *secret;
390 struct sctp_shared_key *ep_key;
391
392 /* If we don't support AUTH, or peer is not capable
393 * we don't need to do anything.
394 */
395 if (!asoc->ep->auth_enable || !asoc->peer.auth_capable)
396 return 0;
397
398 /* If the key_id is non-zero and we couldn't find an
399 * endpoint pair shared key, we can't compute the
400 * secret.
401 * For key_id 0, endpoint pair shared key is a NULL key.
402 */
403 ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
404 BUG_ON(!ep_key);
405
406 secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
407 if (!secret)
408 return -ENOMEM;
409
410 sctp_auth_key_put(asoc->asoc_shared_key);
411 asoc->asoc_shared_key = secret;
412
413 return 0;
414}
415
416
417/* Find the endpoint pair shared key based on the key_id */
418struct sctp_shared_key *sctp_auth_get_shkey(
419 const struct sctp_association *asoc,
420 __u16 key_id)
421{
422 struct sctp_shared_key *key;
423
424 /* First search associations set of endpoint pair shared keys */
425 key_for_each(key, &asoc->endpoint_shared_keys) {
426 if (key->key_id == key_id)
427 return key;
428 }
429
430 return NULL;
431}
432
433/*
434 * Initialize all the possible digest transforms that we can use. Right now
435 * now, the supported digests are SHA1 and SHA256. We do this here once
436 * because of the restrictiong that transforms may only be allocated in
437 * user context. This forces us to pre-allocated all possible transforms
438 * at the endpoint init time.
439 */
440int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
441{
442 struct crypto_hash *tfm = NULL;
443 __u16 id;
444
445 /* If AUTH extension is disabled, we are done */
446 if (!ep->auth_enable) {
447 ep->auth_hmacs = NULL;
448 return 0;
449 }
450
451 /* If the transforms are already allocated, we are done */
452 if (ep->auth_hmacs)
453 return 0;
454
455 /* Allocated the array of pointers to transorms */
456 ep->auth_hmacs = kzalloc(
457 sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
458 gfp);
459 if (!ep->auth_hmacs)
460 return -ENOMEM;
461
462 for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
463
464 /* See is we support the id. Supported IDs have name and
465 * length fields set, so that we can allocated and use
466 * them. We can safely just check for name, for without the
467 * name, we can't allocate the TFM.
468 */
469 if (!sctp_hmac_list[id].hmac_name)
470 continue;
471
472 /* If this TFM has been allocated, we are all set */
473 if (ep->auth_hmacs[id])
474 continue;
475
476 /* Allocate the ID */
477 tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
478 CRYPTO_ALG_ASYNC);
479 if (IS_ERR(tfm))
480 goto out_err;
481
482 ep->auth_hmacs[id] = tfm;
483 }
484
485 return 0;
486
487out_err:
488 /* Clean up any successful allocations */
489 sctp_auth_destroy_hmacs(ep->auth_hmacs);
490 return -ENOMEM;
491}
492
493/* Destroy the hmac tfm array */
494void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
495{
496 int i;
497
498 if (!auth_hmacs)
499 return;
500
501 for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++) {
502 if (auth_hmacs[i])
503 crypto_free_hash(auth_hmacs[i]);
504 }
505 kfree(auth_hmacs);
506}
507
508
509struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
510{
511 return &sctp_hmac_list[hmac_id];
512}
513
514/* Get an hmac description information that we can use to build
515 * the AUTH chunk
516 */
517struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
518{
519 struct sctp_hmac_algo_param *hmacs;
520 __u16 n_elt;
521 __u16 id = 0;
522 int i;
523
524 /* If we have a default entry, use it */
525 if (asoc->default_hmac_id)
526 return &sctp_hmac_list[asoc->default_hmac_id];
527
528 /* Since we do not have a default entry, find the first entry
529 * we support and return that. Do not cache that id.
530 */
531 hmacs = asoc->peer.peer_hmacs;
532 if (!hmacs)
533 return NULL;
534
535 n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
536 for (i = 0; i < n_elt; i++) {
537 id = ntohs(hmacs->hmac_ids[i]);
538
539 /* Check the id is in the supported range. And
540 * see if we support the id. Supported IDs have name and
541 * length fields set, so that we can allocate and use
542 * them. We can safely just check for name, for without the
543 * name, we can't allocate the TFM.
544 */
545 if (id > SCTP_AUTH_HMAC_ID_MAX ||
546 !sctp_hmac_list[id].hmac_name) {
547 id = 0;
548 continue;
549 }
550
551 break;
552 }
553
554 if (id == 0)
555 return NULL;
556
557 return &sctp_hmac_list[id];
558}
559
560static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
561{
562 int found = 0;
563 int i;
564
565 for (i = 0; i < n_elts; i++) {
566 if (hmac_id == hmacs[i]) {
567 found = 1;
568 break;
569 }
570 }
571
572 return found;
573}
574
575/* See if the HMAC_ID is one that we claim as supported */
576int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
577 __be16 hmac_id)
578{
579 struct sctp_hmac_algo_param *hmacs;
580 __u16 n_elt;
581
582 if (!asoc)
583 return 0;
584
585 hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
586 n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
587
588 return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
589}
590
591
592/* Cache the default HMAC id. This to follow this text from SCTP-AUTH:
593 * Section 6.1:
594 * The receiver of a HMAC-ALGO parameter SHOULD use the first listed
595 * algorithm it supports.
596 */
597void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
598 struct sctp_hmac_algo_param *hmacs)
599{
600 struct sctp_endpoint *ep;
601 __u16 id;
602 int i;
603 int n_params;
604
605 /* if the default id is already set, use it */
606 if (asoc->default_hmac_id)
607 return;
608
609 n_params = (ntohs(hmacs->param_hdr.length)
610 - sizeof(sctp_paramhdr_t)) >> 1;
611 ep = asoc->ep;
612 for (i = 0; i < n_params; i++) {
613 id = ntohs(hmacs->hmac_ids[i]);
614
615 /* Check the id is in the supported range */
616 if (id > SCTP_AUTH_HMAC_ID_MAX)
617 continue;
618
619 /* If this TFM has been allocated, use this id */
620 if (ep->auth_hmacs[id]) {
621 asoc->default_hmac_id = id;
622 break;
623 }
624 }
625}
626
627
628/* Check to see if the given chunk is supposed to be authenticated */
629static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
630{
631 unsigned short len;
632 int found = 0;
633 int i;
634
635 if (!param || param->param_hdr.length == 0)
636 return 0;
637
638 len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);
639
640 /* SCTP-AUTH, Section 3.2
641 * The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
642 * chunks MUST NOT be listed in the CHUNKS parameter. However, if
643 * a CHUNKS parameter is received then the types for INIT, INIT-ACK,
644 * SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
645 */
646 for (i = 0; !found && i < len; i++) {
647 switch (param->chunks[i]) {
648 case SCTP_CID_INIT:
649 case SCTP_CID_INIT_ACK:
650 case SCTP_CID_SHUTDOWN_COMPLETE:
651 case SCTP_CID_AUTH:
652 break;
653
654 default:
655 if (param->chunks[i] == chunk)
656 found = 1;
657 break;
658 }
659 }
660
661 return found;
662}
663
664/* Check if peer requested that this chunk is authenticated */
665int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
666{
667 if (!asoc)
668 return 0;
669
670 if (!asoc->ep->auth_enable || !asoc->peer.auth_capable)
671 return 0;
672
673 return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
674}
675
676/* Check if we requested that peer authenticate this chunk. */
677int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
678{
679 if (!asoc)
680 return 0;
681
682 if (!asoc->ep->auth_enable)
683 return 0;
684
685 return __sctp_auth_cid(chunk,
686 (struct sctp_chunks_param *)asoc->c.auth_chunks);
687}
688
689/* SCTP-AUTH: Section 6.2:
690 * The sender MUST calculate the MAC as described in RFC2104 [2] using
691 * the hash function H as described by the MAC Identifier and the shared
692 * association key K based on the endpoint pair shared key described by
693 * the shared key identifier. The 'data' used for the computation of
694 * the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
695 * zero (as shown in Figure 6) followed by all chunks that are placed
696 * after the AUTH chunk in the SCTP packet.
697 */
698void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
699 struct sk_buff *skb,
700 struct sctp_auth_chunk *auth,
701 gfp_t gfp)
702{
703 struct scatterlist sg;
704 struct hash_desc desc;
705 struct sctp_auth_bytes *asoc_key;
706 __u16 key_id, hmac_id;
707 __u8 *digest;
708 unsigned char *end;
709 int free_key = 0;
710
711 /* Extract the info we need:
712 * - hmac id
713 * - key id
714 */
715 key_id = ntohs(auth->auth_hdr.shkey_id);
716 hmac_id = ntohs(auth->auth_hdr.hmac_id);
717
718 if (key_id == asoc->active_key_id)
719 asoc_key = asoc->asoc_shared_key;
720 else {
721 struct sctp_shared_key *ep_key;
722
723 ep_key = sctp_auth_get_shkey(asoc, key_id);
724 if (!ep_key)
725 return;
726
727 asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
728 if (!asoc_key)
729 return;
730
731 free_key = 1;
732 }
733
734 /* set up scatter list */
735 end = skb_tail_pointer(skb);
736 sg_init_one(&sg, auth, end - (unsigned char *)auth);
737
738 desc.tfm = asoc->ep->auth_hmacs[hmac_id];
739 desc.flags = 0;
740
741 digest = auth->auth_hdr.hmac;
742 if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
743 goto free;
744
745 crypto_hash_digest(&desc, &sg, sg.length, digest);
746
747free:
748 if (free_key)
749 sctp_auth_key_put(asoc_key);
750}
751
752/* API Helpers */
753
754/* Add a chunk to the endpoint authenticated chunk list */
755int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
756{
757 struct sctp_chunks_param *p = ep->auth_chunk_list;
758 __u16 nchunks;
759 __u16 param_len;
760
761 /* If this chunk is already specified, we are done */
762 if (__sctp_auth_cid(chunk_id, p))
763 return 0;
764
765 /* Check if we can add this chunk to the array */
766 param_len = ntohs(p->param_hdr.length);
767 nchunks = param_len - sizeof(sctp_paramhdr_t);
768 if (nchunks == SCTP_NUM_CHUNK_TYPES)
769 return -EINVAL;
770
771 p->chunks[nchunks] = chunk_id;
772 p->param_hdr.length = htons(param_len + 1);
773 return 0;
774}
775
776/* Add hmac identifires to the endpoint list of supported hmac ids */
777int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
778 struct sctp_hmacalgo *hmacs)
779{
780 int has_sha1 = 0;
781 __u16 id;
782 int i;
783
784 /* Scan the list looking for unsupported id. Also make sure that
785 * SHA1 is specified.
786 */
787 for (i = 0; i < hmacs->shmac_num_idents; i++) {
788 id = hmacs->shmac_idents[i];
789
790 if (id > SCTP_AUTH_HMAC_ID_MAX)
791 return -EOPNOTSUPP;
792
793 if (SCTP_AUTH_HMAC_ID_SHA1 == id)
794 has_sha1 = 1;
795
796 if (!sctp_hmac_list[id].hmac_name)
797 return -EOPNOTSUPP;
798 }
799
800 if (!has_sha1)
801 return -EINVAL;
802
803 memcpy(ep->auth_hmacs_list->hmac_ids, &hmacs->shmac_idents[0],
804 hmacs->shmac_num_idents * sizeof(__u16));
805 ep->auth_hmacs_list->param_hdr.length = htons(sizeof(sctp_paramhdr_t) +
806 hmacs->shmac_num_idents * sizeof(__u16));
807 return 0;
808}
809
810/* Set a new shared key on either endpoint or association. If the
811 * the key with a same ID already exists, replace the key (remove the
812 * old key and add a new one).
813 */
814int sctp_auth_set_key(struct sctp_endpoint *ep,
815 struct sctp_association *asoc,
816 struct sctp_authkey *auth_key)
817{
818 struct sctp_shared_key *cur_key = NULL;
819 struct sctp_auth_bytes *key;
820 struct list_head *sh_keys;
821 int replace = 0;
822
823 /* Try to find the given key id to see if
824 * we are doing a replace, or adding a new key
825 */
826 if (asoc)
827 sh_keys = &asoc->endpoint_shared_keys;
828 else
829 sh_keys = &ep->endpoint_shared_keys;
830
831 key_for_each(cur_key, sh_keys) {
832 if (cur_key->key_id == auth_key->sca_keynumber) {
833 replace = 1;
834 break;
835 }
836 }
837
838 /* If we are not replacing a key id, we need to allocate
839 * a shared key.
840 */
841 if (!replace) {
842 cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber,
843 GFP_KERNEL);
844 if (!cur_key)
845 return -ENOMEM;
846 }
847
848 /* Create a new key data based on the info passed in */
849 key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
850 if (!key)
851 goto nomem;
852
853 memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);
854
855 /* If we are replacing, remove the old keys data from the
856 * key id. If we are adding new key id, add it to the
857 * list.
858 */
859 if (replace)
860 sctp_auth_key_put(cur_key->key);
861 else
862 list_add(&cur_key->key_list, sh_keys);
863
864 cur_key->key = key;
865 sctp_auth_key_hold(key);
866
867 return 0;
868nomem:
869 if (!replace)
870 sctp_auth_shkey_free(cur_key);
871
872 return -ENOMEM;
873}
874
875int sctp_auth_set_active_key(struct sctp_endpoint *ep,
876 struct sctp_association *asoc,
877 __u16 key_id)
878{
879 struct sctp_shared_key *key;
880 struct list_head *sh_keys;
881 int found = 0;
882
883 /* The key identifier MUST correst to an existing key */
884 if (asoc)
885 sh_keys = &asoc->endpoint_shared_keys;
886 else
887 sh_keys = &ep->endpoint_shared_keys;
888
889 key_for_each(key, sh_keys) {
890 if (key->key_id == key_id) {
891 found = 1;
892 break;
893 }
894 }
895
896 if (!found)
897 return -EINVAL;
898
899 if (asoc) {
900 asoc->active_key_id = key_id;
901 sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL);
902 } else
903 ep->active_key_id = key_id;
904
905 return 0;
906}
907
908int sctp_auth_del_key_id(struct sctp_endpoint *ep,
909 struct sctp_association *asoc,
910 __u16 key_id)
911{
912 struct sctp_shared_key *key;
913 struct list_head *sh_keys;
914 int found = 0;
915
916 /* The key identifier MUST NOT be the current active key
917 * The key identifier MUST correst to an existing key
918 */
919 if (asoc) {
920 if (asoc->active_key_id == key_id)
921 return -EINVAL;
922
923 sh_keys = &asoc->endpoint_shared_keys;
924 } else {
925 if (ep->active_key_id == key_id)
926 return -EINVAL;
927
928 sh_keys = &ep->endpoint_shared_keys;
929 }
930
931 key_for_each(key, sh_keys) {
932 if (key->key_id == key_id) {
933 found = 1;
934 break;
935 }
936 }
937
938 if (!found)
939 return -EINVAL;
940
941 /* Delete the shared key */
942 list_del_init(&key->key_list);
943 sctp_auth_shkey_free(key);
944
945 return 0;
946}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* SCTP kernel implementation
3 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
4 *
5 * This file is part of the SCTP kernel implementation
6 *
7 * Please send any bug reports or fixes you make to the
8 * email address(es):
9 * lksctp developers <linux-sctp@vger.kernel.org>
10 *
11 * Written or modified by:
12 * Vlad Yasevich <vladislav.yasevich@hp.com>
13 */
14
15#include <crypto/hash.h>
16#include <linux/slab.h>
17#include <linux/types.h>
18#include <linux/scatterlist.h>
19#include <net/sctp/sctp.h>
20#include <net/sctp/auth.h>
21
22static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
23 {
24 /* id 0 is reserved. as all 0 */
25 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
26 },
27 {
28 .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
29 .hmac_name = "hmac(sha1)",
30 .hmac_len = SCTP_SHA1_SIG_SIZE,
31 },
32 {
33 /* id 2 is reserved as well */
34 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
35 },
36#if IS_ENABLED(CONFIG_CRYPTO_SHA256)
37 {
38 .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
39 .hmac_name = "hmac(sha256)",
40 .hmac_len = SCTP_SHA256_SIG_SIZE,
41 }
42#endif
43};
44
45
46void sctp_auth_key_put(struct sctp_auth_bytes *key)
47{
48 if (!key)
49 return;
50
51 if (refcount_dec_and_test(&key->refcnt)) {
52 kfree_sensitive(key);
53 SCTP_DBG_OBJCNT_DEC(keys);
54 }
55}
56
57/* Create a new key structure of a given length */
58static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
59{
60 struct sctp_auth_bytes *key;
61
62 /* Verify that we are not going to overflow INT_MAX */
63 if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
64 return NULL;
65
66 /* Allocate the shared key */
67 key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
68 if (!key)
69 return NULL;
70
71 key->len = key_len;
72 refcount_set(&key->refcnt, 1);
73 SCTP_DBG_OBJCNT_INC(keys);
74
75 return key;
76}
77
78/* Create a new shared key container with a give key id */
79struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
80{
81 struct sctp_shared_key *new;
82
83 /* Allocate the shared key container */
84 new = kzalloc(sizeof(struct sctp_shared_key), gfp);
85 if (!new)
86 return NULL;
87
88 INIT_LIST_HEAD(&new->key_list);
89 refcount_set(&new->refcnt, 1);
90 new->key_id = key_id;
91
92 return new;
93}
94
95/* Free the shared key structure */
96static void sctp_auth_shkey_destroy(struct sctp_shared_key *sh_key)
97{
98 BUG_ON(!list_empty(&sh_key->key_list));
99 sctp_auth_key_put(sh_key->key);
100 sh_key->key = NULL;
101 kfree(sh_key);
102}
103
104void sctp_auth_shkey_release(struct sctp_shared_key *sh_key)
105{
106 if (refcount_dec_and_test(&sh_key->refcnt))
107 sctp_auth_shkey_destroy(sh_key);
108}
109
110void sctp_auth_shkey_hold(struct sctp_shared_key *sh_key)
111{
112 refcount_inc(&sh_key->refcnt);
113}
114
115/* Destroy the entire key list. This is done during the
116 * associon and endpoint free process.
117 */
118void sctp_auth_destroy_keys(struct list_head *keys)
119{
120 struct sctp_shared_key *ep_key;
121 struct sctp_shared_key *tmp;
122
123 if (list_empty(keys))
124 return;
125
126 key_for_each_safe(ep_key, tmp, keys) {
127 list_del_init(&ep_key->key_list);
128 sctp_auth_shkey_release(ep_key);
129 }
130}
131
132/* Compare two byte vectors as numbers. Return values
133 * are:
134 * 0 - vectors are equal
135 * < 0 - vector 1 is smaller than vector2
136 * > 0 - vector 1 is greater than vector2
137 *
138 * Algorithm is:
139 * This is performed by selecting the numerically smaller key vector...
140 * If the key vectors are equal as numbers but differ in length ...
141 * the shorter vector is considered smaller
142 *
143 * Examples (with small values):
144 * 000123456789 > 123456789 (first number is longer)
145 * 000123456789 < 234567891 (second number is larger numerically)
146 * 123456789 > 2345678 (first number is both larger & longer)
147 */
148static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
149 struct sctp_auth_bytes *vector2)
150{
151 int diff;
152 int i;
153 const __u8 *longer;
154
155 diff = vector1->len - vector2->len;
156 if (diff) {
157 longer = (diff > 0) ? vector1->data : vector2->data;
158
159 /* Check to see if the longer number is
160 * lead-zero padded. If it is not, it
161 * is automatically larger numerically.
162 */
163 for (i = 0; i < abs(diff); i++) {
164 if (longer[i] != 0)
165 return diff;
166 }
167 }
168
169 /* lengths are the same, compare numbers */
170 return memcmp(vector1->data, vector2->data, vector1->len);
171}
172
173/*
174 * Create a key vector as described in SCTP-AUTH, Section 6.1
175 * The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
176 * parameter sent by each endpoint are concatenated as byte vectors.
177 * These parameters include the parameter type, parameter length, and
178 * the parameter value, but padding is omitted; all padding MUST be
179 * removed from this concatenation before proceeding with further
180 * computation of keys. Parameters which were not sent are simply
181 * omitted from the concatenation process. The resulting two vectors
182 * are called the two key vectors.
183 */
184static struct sctp_auth_bytes *sctp_auth_make_key_vector(
185 struct sctp_random_param *random,
186 struct sctp_chunks_param *chunks,
187 struct sctp_hmac_algo_param *hmacs,
188 gfp_t gfp)
189{
190 struct sctp_auth_bytes *new;
191 __u32 len;
192 __u32 offset = 0;
193 __u16 random_len, hmacs_len, chunks_len = 0;
194
195 random_len = ntohs(random->param_hdr.length);
196 hmacs_len = ntohs(hmacs->param_hdr.length);
197 if (chunks)
198 chunks_len = ntohs(chunks->param_hdr.length);
199
200 len = random_len + hmacs_len + chunks_len;
201
202 new = sctp_auth_create_key(len, gfp);
203 if (!new)
204 return NULL;
205
206 memcpy(new->data, random, random_len);
207 offset += random_len;
208
209 if (chunks) {
210 memcpy(new->data + offset, chunks, chunks_len);
211 offset += chunks_len;
212 }
213
214 memcpy(new->data + offset, hmacs, hmacs_len);
215
216 return new;
217}
218
219
220/* Make a key vector based on our local parameters */
221static struct sctp_auth_bytes *sctp_auth_make_local_vector(
222 const struct sctp_association *asoc,
223 gfp_t gfp)
224{
225 return sctp_auth_make_key_vector(
226 (struct sctp_random_param *)asoc->c.auth_random,
227 (struct sctp_chunks_param *)asoc->c.auth_chunks,
228 (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs, gfp);
229}
230
231/* Make a key vector based on peer's parameters */
232static struct sctp_auth_bytes *sctp_auth_make_peer_vector(
233 const struct sctp_association *asoc,
234 gfp_t gfp)
235{
236 return sctp_auth_make_key_vector(asoc->peer.peer_random,
237 asoc->peer.peer_chunks,
238 asoc->peer.peer_hmacs,
239 gfp);
240}
241
242
243/* Set the value of the association shared key base on the parameters
244 * given. The algorithm is:
245 * From the endpoint pair shared keys and the key vectors the
246 * association shared keys are computed. This is performed by selecting
247 * the numerically smaller key vector and concatenating it to the
248 * endpoint pair shared key, and then concatenating the numerically
249 * larger key vector to that. The result of the concatenation is the
250 * association shared key.
251 */
252static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
253 struct sctp_shared_key *ep_key,
254 struct sctp_auth_bytes *first_vector,
255 struct sctp_auth_bytes *last_vector,
256 gfp_t gfp)
257{
258 struct sctp_auth_bytes *secret;
259 __u32 offset = 0;
260 __u32 auth_len;
261
262 auth_len = first_vector->len + last_vector->len;
263 if (ep_key->key)
264 auth_len += ep_key->key->len;
265
266 secret = sctp_auth_create_key(auth_len, gfp);
267 if (!secret)
268 return NULL;
269
270 if (ep_key->key) {
271 memcpy(secret->data, ep_key->key->data, ep_key->key->len);
272 offset += ep_key->key->len;
273 }
274
275 memcpy(secret->data + offset, first_vector->data, first_vector->len);
276 offset += first_vector->len;
277
278 memcpy(secret->data + offset, last_vector->data, last_vector->len);
279
280 return secret;
281}
282
283/* Create an association shared key. Follow the algorithm
284 * described in SCTP-AUTH, Section 6.1
285 */
286static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
287 const struct sctp_association *asoc,
288 struct sctp_shared_key *ep_key,
289 gfp_t gfp)
290{
291 struct sctp_auth_bytes *local_key_vector;
292 struct sctp_auth_bytes *peer_key_vector;
293 struct sctp_auth_bytes *first_vector,
294 *last_vector;
295 struct sctp_auth_bytes *secret = NULL;
296 int cmp;
297
298
299 /* Now we need to build the key vectors
300 * SCTP-AUTH , Section 6.1
301 * The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
302 * parameter sent by each endpoint are concatenated as byte vectors.
303 * These parameters include the parameter type, parameter length, and
304 * the parameter value, but padding is omitted; all padding MUST be
305 * removed from this concatenation before proceeding with further
306 * computation of keys. Parameters which were not sent are simply
307 * omitted from the concatenation process. The resulting two vectors
308 * are called the two key vectors.
309 */
310
311 local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
312 peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
313
314 if (!peer_key_vector || !local_key_vector)
315 goto out;
316
317 /* Figure out the order in which the key_vectors will be
318 * added to the endpoint shared key.
319 * SCTP-AUTH, Section 6.1:
320 * This is performed by selecting the numerically smaller key
321 * vector and concatenating it to the endpoint pair shared
322 * key, and then concatenating the numerically larger key
323 * vector to that. If the key vectors are equal as numbers
324 * but differ in length, then the concatenation order is the
325 * endpoint shared key, followed by the shorter key vector,
326 * followed by the longer key vector. Otherwise, the key
327 * vectors are identical, and may be concatenated to the
328 * endpoint pair key in any order.
329 */
330 cmp = sctp_auth_compare_vectors(local_key_vector,
331 peer_key_vector);
332 if (cmp < 0) {
333 first_vector = local_key_vector;
334 last_vector = peer_key_vector;
335 } else {
336 first_vector = peer_key_vector;
337 last_vector = local_key_vector;
338 }
339
340 secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
341 gfp);
342out:
343 sctp_auth_key_put(local_key_vector);
344 sctp_auth_key_put(peer_key_vector);
345
346 return secret;
347}
348
349/*
350 * Populate the association overlay list with the list
351 * from the endpoint.
352 */
353int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
354 struct sctp_association *asoc,
355 gfp_t gfp)
356{
357 struct sctp_shared_key *sh_key;
358 struct sctp_shared_key *new;
359
360 BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
361
362 key_for_each(sh_key, &ep->endpoint_shared_keys) {
363 new = sctp_auth_shkey_create(sh_key->key_id, gfp);
364 if (!new)
365 goto nomem;
366
367 new->key = sh_key->key;
368 sctp_auth_key_hold(new->key);
369 list_add(&new->key_list, &asoc->endpoint_shared_keys);
370 }
371
372 return 0;
373
374nomem:
375 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
376 return -ENOMEM;
377}
378
379
380/* Public interface to create the association shared key.
381 * See code above for the algorithm.
382 */
383int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
384{
385 struct sctp_auth_bytes *secret;
386 struct sctp_shared_key *ep_key;
387 struct sctp_chunk *chunk;
388
389 /* If we don't support AUTH, or peer is not capable
390 * we don't need to do anything.
391 */
392 if (!asoc->peer.auth_capable)
393 return 0;
394
395 /* If the key_id is non-zero and we couldn't find an
396 * endpoint pair shared key, we can't compute the
397 * secret.
398 * For key_id 0, endpoint pair shared key is a NULL key.
399 */
400 ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
401 BUG_ON(!ep_key);
402
403 secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
404 if (!secret)
405 return -ENOMEM;
406
407 sctp_auth_key_put(asoc->asoc_shared_key);
408 asoc->asoc_shared_key = secret;
409 asoc->shkey = ep_key;
410
411 /* Update send queue in case any chunk already in there now
412 * needs authenticating
413 */
414 list_for_each_entry(chunk, &asoc->outqueue.out_chunk_list, list) {
415 if (sctp_auth_send_cid(chunk->chunk_hdr->type, asoc)) {
416 chunk->auth = 1;
417 if (!chunk->shkey) {
418 chunk->shkey = asoc->shkey;
419 sctp_auth_shkey_hold(chunk->shkey);
420 }
421 }
422 }
423
424 return 0;
425}
426
427
428/* Find the endpoint pair shared key based on the key_id */
429struct sctp_shared_key *sctp_auth_get_shkey(
430 const struct sctp_association *asoc,
431 __u16 key_id)
432{
433 struct sctp_shared_key *key;
434
435 /* First search associations set of endpoint pair shared keys */
436 key_for_each(key, &asoc->endpoint_shared_keys) {
437 if (key->key_id == key_id) {
438 if (!key->deactivated)
439 return key;
440 break;
441 }
442 }
443
444 return NULL;
445}
446
447/*
448 * Initialize all the possible digest transforms that we can use. Right
449 * now, the supported digests are SHA1 and SHA256. We do this here once
450 * because of the restrictiong that transforms may only be allocated in
451 * user context. This forces us to pre-allocated all possible transforms
452 * at the endpoint init time.
453 */
454int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
455{
456 struct crypto_shash *tfm = NULL;
457 __u16 id;
458
459 /* If the transforms are already allocated, we are done */
460 if (ep->auth_hmacs)
461 return 0;
462
463 /* Allocated the array of pointers to transorms */
464 ep->auth_hmacs = kcalloc(SCTP_AUTH_NUM_HMACS,
465 sizeof(struct crypto_shash *),
466 gfp);
467 if (!ep->auth_hmacs)
468 return -ENOMEM;
469
470 for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
471
472 /* See is we support the id. Supported IDs have name and
473 * length fields set, so that we can allocated and use
474 * them. We can safely just check for name, for without the
475 * name, we can't allocate the TFM.
476 */
477 if (!sctp_hmac_list[id].hmac_name)
478 continue;
479
480 /* If this TFM has been allocated, we are all set */
481 if (ep->auth_hmacs[id])
482 continue;
483
484 /* Allocate the ID */
485 tfm = crypto_alloc_shash(sctp_hmac_list[id].hmac_name, 0, 0);
486 if (IS_ERR(tfm))
487 goto out_err;
488
489 ep->auth_hmacs[id] = tfm;
490 }
491
492 return 0;
493
494out_err:
495 /* Clean up any successful allocations */
496 sctp_auth_destroy_hmacs(ep->auth_hmacs);
497 ep->auth_hmacs = NULL;
498 return -ENOMEM;
499}
500
501/* Destroy the hmac tfm array */
502void sctp_auth_destroy_hmacs(struct crypto_shash *auth_hmacs[])
503{
504 int i;
505
506 if (!auth_hmacs)
507 return;
508
509 for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++) {
510 crypto_free_shash(auth_hmacs[i]);
511 }
512 kfree(auth_hmacs);
513}
514
515
516struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
517{
518 return &sctp_hmac_list[hmac_id];
519}
520
521/* Get an hmac description information that we can use to build
522 * the AUTH chunk
523 */
524struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
525{
526 struct sctp_hmac_algo_param *hmacs;
527 __u16 n_elt;
528 __u16 id = 0;
529 int i;
530
531 /* If we have a default entry, use it */
532 if (asoc->default_hmac_id)
533 return &sctp_hmac_list[asoc->default_hmac_id];
534
535 /* Since we do not have a default entry, find the first entry
536 * we support and return that. Do not cache that id.
537 */
538 hmacs = asoc->peer.peer_hmacs;
539 if (!hmacs)
540 return NULL;
541
542 n_elt = (ntohs(hmacs->param_hdr.length) -
543 sizeof(struct sctp_paramhdr)) >> 1;
544 for (i = 0; i < n_elt; i++) {
545 id = ntohs(hmacs->hmac_ids[i]);
546
547 /* Check the id is in the supported range. And
548 * see if we support the id. Supported IDs have name and
549 * length fields set, so that we can allocate and use
550 * them. We can safely just check for name, for without the
551 * name, we can't allocate the TFM.
552 */
553 if (id > SCTP_AUTH_HMAC_ID_MAX ||
554 !sctp_hmac_list[id].hmac_name) {
555 id = 0;
556 continue;
557 }
558
559 break;
560 }
561
562 if (id == 0)
563 return NULL;
564
565 return &sctp_hmac_list[id];
566}
567
568static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
569{
570 int found = 0;
571 int i;
572
573 for (i = 0; i < n_elts; i++) {
574 if (hmac_id == hmacs[i]) {
575 found = 1;
576 break;
577 }
578 }
579
580 return found;
581}
582
583/* See if the HMAC_ID is one that we claim as supported */
584int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
585 __be16 hmac_id)
586{
587 struct sctp_hmac_algo_param *hmacs;
588 __u16 n_elt;
589
590 if (!asoc)
591 return 0;
592
593 hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
594 n_elt = (ntohs(hmacs->param_hdr.length) -
595 sizeof(struct sctp_paramhdr)) >> 1;
596
597 return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
598}
599
600
601/* Cache the default HMAC id. This to follow this text from SCTP-AUTH:
602 * Section 6.1:
603 * The receiver of a HMAC-ALGO parameter SHOULD use the first listed
604 * algorithm it supports.
605 */
606void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
607 struct sctp_hmac_algo_param *hmacs)
608{
609 struct sctp_endpoint *ep;
610 __u16 id;
611 int i;
612 int n_params;
613
614 /* if the default id is already set, use it */
615 if (asoc->default_hmac_id)
616 return;
617
618 n_params = (ntohs(hmacs->param_hdr.length) -
619 sizeof(struct sctp_paramhdr)) >> 1;
620 ep = asoc->ep;
621 for (i = 0; i < n_params; i++) {
622 id = ntohs(hmacs->hmac_ids[i]);
623
624 /* Check the id is in the supported range */
625 if (id > SCTP_AUTH_HMAC_ID_MAX)
626 continue;
627
628 /* If this TFM has been allocated, use this id */
629 if (ep->auth_hmacs[id]) {
630 asoc->default_hmac_id = id;
631 break;
632 }
633 }
634}
635
636
637/* Check to see if the given chunk is supposed to be authenticated */
638static int __sctp_auth_cid(enum sctp_cid chunk, struct sctp_chunks_param *param)
639{
640 unsigned short len;
641 int found = 0;
642 int i;
643
644 if (!param || param->param_hdr.length == 0)
645 return 0;
646
647 len = ntohs(param->param_hdr.length) - sizeof(struct sctp_paramhdr);
648
649 /* SCTP-AUTH, Section 3.2
650 * The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
651 * chunks MUST NOT be listed in the CHUNKS parameter. However, if
652 * a CHUNKS parameter is received then the types for INIT, INIT-ACK,
653 * SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
654 */
655 for (i = 0; !found && i < len; i++) {
656 switch (param->chunks[i]) {
657 case SCTP_CID_INIT:
658 case SCTP_CID_INIT_ACK:
659 case SCTP_CID_SHUTDOWN_COMPLETE:
660 case SCTP_CID_AUTH:
661 break;
662
663 default:
664 if (param->chunks[i] == chunk)
665 found = 1;
666 break;
667 }
668 }
669
670 return found;
671}
672
673/* Check if peer requested that this chunk is authenticated */
674int sctp_auth_send_cid(enum sctp_cid chunk, const struct sctp_association *asoc)
675{
676 if (!asoc)
677 return 0;
678
679 if (!asoc->peer.auth_capable)
680 return 0;
681
682 return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
683}
684
685/* Check if we requested that peer authenticate this chunk. */
686int sctp_auth_recv_cid(enum sctp_cid chunk, const struct sctp_association *asoc)
687{
688 if (!asoc)
689 return 0;
690
691 if (!asoc->peer.auth_capable)
692 return 0;
693
694 return __sctp_auth_cid(chunk,
695 (struct sctp_chunks_param *)asoc->c.auth_chunks);
696}
697
698/* SCTP-AUTH: Section 6.2:
699 * The sender MUST calculate the MAC as described in RFC2104 [2] using
700 * the hash function H as described by the MAC Identifier and the shared
701 * association key K based on the endpoint pair shared key described by
702 * the shared key identifier. The 'data' used for the computation of
703 * the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
704 * zero (as shown in Figure 6) followed by all chunks that are placed
705 * after the AUTH chunk in the SCTP packet.
706 */
707void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
708 struct sk_buff *skb, struct sctp_auth_chunk *auth,
709 struct sctp_shared_key *ep_key, gfp_t gfp)
710{
711 struct sctp_auth_bytes *asoc_key;
712 struct crypto_shash *tfm;
713 __u16 key_id, hmac_id;
714 unsigned char *end;
715 int free_key = 0;
716 __u8 *digest;
717
718 /* Extract the info we need:
719 * - hmac id
720 * - key id
721 */
722 key_id = ntohs(auth->auth_hdr.shkey_id);
723 hmac_id = ntohs(auth->auth_hdr.hmac_id);
724
725 if (key_id == asoc->active_key_id)
726 asoc_key = asoc->asoc_shared_key;
727 else {
728 /* ep_key can't be NULL here */
729 asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
730 if (!asoc_key)
731 return;
732
733 free_key = 1;
734 }
735
736 /* set up scatter list */
737 end = skb_tail_pointer(skb);
738
739 tfm = asoc->ep->auth_hmacs[hmac_id];
740
741 digest = auth->auth_hdr.hmac;
742 if (crypto_shash_setkey(tfm, &asoc_key->data[0], asoc_key->len))
743 goto free;
744
745 crypto_shash_tfm_digest(tfm, (u8 *)auth, end - (unsigned char *)auth,
746 digest);
747
748free:
749 if (free_key)
750 sctp_auth_key_put(asoc_key);
751}
752
753/* API Helpers */
754
755/* Add a chunk to the endpoint authenticated chunk list */
756int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
757{
758 struct sctp_chunks_param *p = ep->auth_chunk_list;
759 __u16 nchunks;
760 __u16 param_len;
761
762 /* If this chunk is already specified, we are done */
763 if (__sctp_auth_cid(chunk_id, p))
764 return 0;
765
766 /* Check if we can add this chunk to the array */
767 param_len = ntohs(p->param_hdr.length);
768 nchunks = param_len - sizeof(struct sctp_paramhdr);
769 if (nchunks == SCTP_NUM_CHUNK_TYPES)
770 return -EINVAL;
771
772 p->chunks[nchunks] = chunk_id;
773 p->param_hdr.length = htons(param_len + 1);
774 return 0;
775}
776
777/* Add hmac identifires to the endpoint list of supported hmac ids */
778int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
779 struct sctp_hmacalgo *hmacs)
780{
781 int has_sha1 = 0;
782 __u16 id;
783 int i;
784
785 /* Scan the list looking for unsupported id. Also make sure that
786 * SHA1 is specified.
787 */
788 for (i = 0; i < hmacs->shmac_num_idents; i++) {
789 id = hmacs->shmac_idents[i];
790
791 if (id > SCTP_AUTH_HMAC_ID_MAX)
792 return -EOPNOTSUPP;
793
794 if (SCTP_AUTH_HMAC_ID_SHA1 == id)
795 has_sha1 = 1;
796
797 if (!sctp_hmac_list[id].hmac_name)
798 return -EOPNOTSUPP;
799 }
800
801 if (!has_sha1)
802 return -EINVAL;
803
804 for (i = 0; i < hmacs->shmac_num_idents; i++)
805 ep->auth_hmacs_list->hmac_ids[i] =
806 htons(hmacs->shmac_idents[i]);
807 ep->auth_hmacs_list->param_hdr.length =
808 htons(sizeof(struct sctp_paramhdr) +
809 hmacs->shmac_num_idents * sizeof(__u16));
810 return 0;
811}
812
813/* Set a new shared key on either endpoint or association. If the
814 * key with a same ID already exists, replace the key (remove the
815 * old key and add a new one).
816 */
817int sctp_auth_set_key(struct sctp_endpoint *ep,
818 struct sctp_association *asoc,
819 struct sctp_authkey *auth_key)
820{
821 struct sctp_shared_key *cur_key, *shkey;
822 struct sctp_auth_bytes *key;
823 struct list_head *sh_keys;
824 int replace = 0;
825
826 /* Try to find the given key id to see if
827 * we are doing a replace, or adding a new key
828 */
829 if (asoc) {
830 if (!asoc->peer.auth_capable)
831 return -EACCES;
832 sh_keys = &asoc->endpoint_shared_keys;
833 } else {
834 if (!ep->auth_enable)
835 return -EACCES;
836 sh_keys = &ep->endpoint_shared_keys;
837 }
838
839 key_for_each(shkey, sh_keys) {
840 if (shkey->key_id == auth_key->sca_keynumber) {
841 replace = 1;
842 break;
843 }
844 }
845
846 cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber, GFP_KERNEL);
847 if (!cur_key)
848 return -ENOMEM;
849
850 /* Create a new key data based on the info passed in */
851 key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
852 if (!key) {
853 kfree(cur_key);
854 return -ENOMEM;
855 }
856
857 memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);
858 cur_key->key = key;
859
860 if (!replace) {
861 list_add(&cur_key->key_list, sh_keys);
862 return 0;
863 }
864
865 list_del_init(&shkey->key_list);
866 list_add(&cur_key->key_list, sh_keys);
867
868 if (asoc && asoc->active_key_id == auth_key->sca_keynumber &&
869 sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL)) {
870 list_del_init(&cur_key->key_list);
871 sctp_auth_shkey_release(cur_key);
872 list_add(&shkey->key_list, sh_keys);
873 return -ENOMEM;
874 }
875
876 sctp_auth_shkey_release(shkey);
877 return 0;
878}
879
880int sctp_auth_set_active_key(struct sctp_endpoint *ep,
881 struct sctp_association *asoc,
882 __u16 key_id)
883{
884 struct sctp_shared_key *key;
885 struct list_head *sh_keys;
886 int found = 0;
887
888 /* The key identifier MUST correst to an existing key */
889 if (asoc) {
890 if (!asoc->peer.auth_capable)
891 return -EACCES;
892 sh_keys = &asoc->endpoint_shared_keys;
893 } else {
894 if (!ep->auth_enable)
895 return -EACCES;
896 sh_keys = &ep->endpoint_shared_keys;
897 }
898
899 key_for_each(key, sh_keys) {
900 if (key->key_id == key_id) {
901 found = 1;
902 break;
903 }
904 }
905
906 if (!found || key->deactivated)
907 return -EINVAL;
908
909 if (asoc) {
910 __u16 active_key_id = asoc->active_key_id;
911
912 asoc->active_key_id = key_id;
913 if (sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL)) {
914 asoc->active_key_id = active_key_id;
915 return -ENOMEM;
916 }
917 } else
918 ep->active_key_id = key_id;
919
920 return 0;
921}
922
923int sctp_auth_del_key_id(struct sctp_endpoint *ep,
924 struct sctp_association *asoc,
925 __u16 key_id)
926{
927 struct sctp_shared_key *key;
928 struct list_head *sh_keys;
929 int found = 0;
930
931 /* The key identifier MUST NOT be the current active key
932 * The key identifier MUST correst to an existing key
933 */
934 if (asoc) {
935 if (!asoc->peer.auth_capable)
936 return -EACCES;
937 if (asoc->active_key_id == key_id)
938 return -EINVAL;
939
940 sh_keys = &asoc->endpoint_shared_keys;
941 } else {
942 if (!ep->auth_enable)
943 return -EACCES;
944 if (ep->active_key_id == key_id)
945 return -EINVAL;
946
947 sh_keys = &ep->endpoint_shared_keys;
948 }
949
950 key_for_each(key, sh_keys) {
951 if (key->key_id == key_id) {
952 found = 1;
953 break;
954 }
955 }
956
957 if (!found)
958 return -EINVAL;
959
960 /* Delete the shared key */
961 list_del_init(&key->key_list);
962 sctp_auth_shkey_release(key);
963
964 return 0;
965}
966
967int sctp_auth_deact_key_id(struct sctp_endpoint *ep,
968 struct sctp_association *asoc, __u16 key_id)
969{
970 struct sctp_shared_key *key;
971 struct list_head *sh_keys;
972 int found = 0;
973
974 /* The key identifier MUST NOT be the current active key
975 * The key identifier MUST correst to an existing key
976 */
977 if (asoc) {
978 if (!asoc->peer.auth_capable)
979 return -EACCES;
980 if (asoc->active_key_id == key_id)
981 return -EINVAL;
982
983 sh_keys = &asoc->endpoint_shared_keys;
984 } else {
985 if (!ep->auth_enable)
986 return -EACCES;
987 if (ep->active_key_id == key_id)
988 return -EINVAL;
989
990 sh_keys = &ep->endpoint_shared_keys;
991 }
992
993 key_for_each(key, sh_keys) {
994 if (key->key_id == key_id) {
995 found = 1;
996 break;
997 }
998 }
999
1000 if (!found)
1001 return -EINVAL;
1002
1003 /* refcnt == 1 and !list_empty mean it's not being used anywhere
1004 * and deactivated will be set, so it's time to notify userland
1005 * that this shkey can be freed.
1006 */
1007 if (asoc && !list_empty(&key->key_list) &&
1008 refcount_read(&key->refcnt) == 1) {
1009 struct sctp_ulpevent *ev;
1010
1011 ev = sctp_ulpevent_make_authkey(asoc, key->key_id,
1012 SCTP_AUTH_FREE_KEY, GFP_KERNEL);
1013 if (ev)
1014 asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
1015 }
1016
1017 key->deactivated = 1;
1018
1019 return 0;
1020}
1021
1022int sctp_auth_init(struct sctp_endpoint *ep, gfp_t gfp)
1023{
1024 int err = -ENOMEM;
1025
1026 /* Allocate space for HMACS and CHUNKS authentication
1027 * variables. There are arrays that we encode directly
1028 * into parameters to make the rest of the operations easier.
1029 */
1030 if (!ep->auth_hmacs_list) {
1031 struct sctp_hmac_algo_param *auth_hmacs;
1032
1033 auth_hmacs = kzalloc(struct_size(auth_hmacs, hmac_ids,
1034 SCTP_AUTH_NUM_HMACS), gfp);
1035 if (!auth_hmacs)
1036 goto nomem;
1037 /* Initialize the HMACS parameter.
1038 * SCTP-AUTH: Section 3.3
1039 * Every endpoint supporting SCTP chunk authentication MUST
1040 * support the HMAC based on the SHA-1 algorithm.
1041 */
1042 auth_hmacs->param_hdr.type = SCTP_PARAM_HMAC_ALGO;
1043 auth_hmacs->param_hdr.length =
1044 htons(sizeof(struct sctp_paramhdr) + 2);
1045 auth_hmacs->hmac_ids[0] = htons(SCTP_AUTH_HMAC_ID_SHA1);
1046 ep->auth_hmacs_list = auth_hmacs;
1047 }
1048
1049 if (!ep->auth_chunk_list) {
1050 struct sctp_chunks_param *auth_chunks;
1051
1052 auth_chunks = kzalloc(sizeof(*auth_chunks) +
1053 SCTP_NUM_CHUNK_TYPES, gfp);
1054 if (!auth_chunks)
1055 goto nomem;
1056 /* Initialize the CHUNKS parameter */
1057 auth_chunks->param_hdr.type = SCTP_PARAM_CHUNKS;
1058 auth_chunks->param_hdr.length =
1059 htons(sizeof(struct sctp_paramhdr));
1060 ep->auth_chunk_list = auth_chunks;
1061 }
1062
1063 /* Allocate and initialize transorms arrays for supported
1064 * HMACs.
1065 */
1066 err = sctp_auth_init_hmacs(ep, gfp);
1067 if (err)
1068 goto nomem;
1069
1070 return 0;
1071
1072nomem:
1073 /* Free all allocations */
1074 kfree(ep->auth_hmacs_list);
1075 kfree(ep->auth_chunk_list);
1076 ep->auth_hmacs_list = NULL;
1077 ep->auth_chunk_list = NULL;
1078 return err;
1079}
1080
1081void sctp_auth_free(struct sctp_endpoint *ep)
1082{
1083 kfree(ep->auth_hmacs_list);
1084 kfree(ep->auth_chunk_list);
1085 ep->auth_hmacs_list = NULL;
1086 ep->auth_chunk_list = NULL;
1087 sctp_auth_destroy_hmacs(ep->auth_hmacs);
1088 ep->auth_hmacs = NULL;
1089}