blob: 2a29409a38d92c40b0af0f325fc1b5a1cb715fa4 [file] [log] [blame]
Vlad Yasevich1f485642007-10-09 01:15:59 -07001/* SCTP kernel reference Implementation
2 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
3 *
4 * This file is part of the SCTP kernel reference Implementation
5 *
6 * The SCTP reference 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 * The SCTP reference 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, write to
20 * the Free Software Foundation, 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
22 *
23 * Please send any bug reports or fixes you make to the
24 * email address(es):
25 * lksctp developers <lksctp-developers@lists.sourceforge.net>
26 *
27 * Or submit a bug report through the following website:
28 * http://www.sf.net/projects/lksctp
29 *
30 * Written or modified by:
31 * Vlad Yasevich <vladislav.yasevich@hp.com>
32 *
33 * Any bugs reported given to us we will try to fix... any fixes shared will
34 * be incorporated into the next SCTP release.
35 */
36
37#include <linux/types.h>
38#include <linux/crypto.h>
39#include <linux/scatterlist.h>
40#include <net/sctp/sctp.h>
41#include <net/sctp/auth.h>
42
43static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
44 {
45 /* id 0 is reserved. as all 0 */
46 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
47 },
48 {
49 .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
50 .hmac_name="hmac(sha1)",
51 .hmac_len = SCTP_SHA1_SIG_SIZE,
52 },
53 {
54 /* id 2 is reserved as well */
55 .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
56 },
57 {
58 .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
59 .hmac_name="hmac(sha256)",
60 .hmac_len = SCTP_SHA256_SIG_SIZE,
61 }
62};
63
64
65void sctp_auth_key_put(struct sctp_auth_bytes *key)
66{
67 if (!key)
68 return;
69
70 if (atomic_dec_and_test(&key->refcnt)) {
71 kfree(key);
72 SCTP_DBG_OBJCNT_DEC(keys);
73 }
74}
75
76/* Create a new key structure of a given length */
77static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
78{
79 struct sctp_auth_bytes *key;
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 stucture */
110void 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/* Destory 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 then vector2
139 * > 0 - vector 1 is greater then 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
197 len = ntohs(random->param_hdr.length) + ntohs(hmacs->param_hdr.length);
198 if (chunks)
199 len += ntohs(chunks->param_hdr.length);
200
201 new = kmalloc(sizeof(struct sctp_auth_bytes) + len, gfp);
202 if (!new)
203 return NULL;
204
205 new->len = len;
206
207 memcpy(new->data, random, ntohs(random->param_hdr.length));
208 offset += ntohs(random->param_hdr.length);
209
210 if (chunks) {
211 memcpy(new->data + offset, chunks,
212 ntohs(chunks->param_hdr.length));
213 offset += ntohs(chunks->param_hdr.length);
214 }
215
216 memcpy(new->data + offset, hmacs, ntohs(hmacs->param_hdr.length));
217
218 return new;
219}
220
221
222/* Make a key vector based on our local parameters */
223struct sctp_auth_bytes *sctp_auth_make_local_vector(
224 const struct sctp_association *asoc,
225 gfp_t gfp)
226{
227 return sctp_auth_make_key_vector(
228 (sctp_random_param_t*)asoc->c.auth_random,
229 (sctp_chunks_param_t*)asoc->c.auth_chunks,
230 (sctp_hmac_algo_param_t*)asoc->c.auth_hmacs,
231 gfp);
232}
233
234/* Make a key vector based on peer's parameters */
235struct sctp_auth_bytes *sctp_auth_make_peer_vector(
236 const struct sctp_association *asoc,
237 gfp_t gfp)
238{
239 return sctp_auth_make_key_vector(asoc->peer.peer_random,
240 asoc->peer.peer_chunks,
241 asoc->peer.peer_hmacs,
242 gfp);
243}
244
245
246/* Set the value of the association shared key base on the parameters
247 * given. The algorithm is:
248 * From the endpoint pair shared keys and the key vectors the
249 * association shared keys are computed. This is performed by selecting
250 * the numerically smaller key vector and concatenating it to the
251 * endpoint pair shared key, and then concatenating the numerically
252 * larger key vector to that. The result of the concatenation is the
253 * association shared key.
254 */
255static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
256 struct sctp_shared_key *ep_key,
257 struct sctp_auth_bytes *first_vector,
258 struct sctp_auth_bytes *last_vector,
259 gfp_t gfp)
260{
261 struct sctp_auth_bytes *secret;
262 __u32 offset = 0;
263 __u32 auth_len;
264
265 auth_len = first_vector->len + last_vector->len;
266 if (ep_key->key)
267 auth_len += ep_key->key->len;
268
269 secret = sctp_auth_create_key(auth_len, gfp);
270 if (!secret)
271 return NULL;
272
273 if (ep_key->key) {
274 memcpy(secret->data, ep_key->key->data, ep_key->key->len);
275 offset += ep_key->key->len;
276 }
277
278 memcpy(secret->data + offset, first_vector->data, first_vector->len);
279 offset += first_vector->len;
280
281 memcpy(secret->data + offset, last_vector->data, last_vector->len);
282
283 return secret;
284}
285
286/* Create an association shared key. Follow the algorithm
287 * described in SCTP-AUTH, Section 6.1
288 */
289static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
290 const struct sctp_association *asoc,
291 struct sctp_shared_key *ep_key,
292 gfp_t gfp)
293{
294 struct sctp_auth_bytes *local_key_vector;
295 struct sctp_auth_bytes *peer_key_vector;
296 struct sctp_auth_bytes *first_vector,
297 *last_vector;
298 struct sctp_auth_bytes *secret = NULL;
299 int cmp;
300
301
302 /* Now we need to build the key vectors
303 * SCTP-AUTH , Section 6.1
304 * The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
305 * parameter sent by each endpoint are concatenated as byte vectors.
306 * These parameters include the parameter type, parameter length, and
307 * the parameter value, but padding is omitted; all padding MUST be
308 * removed from this concatenation before proceeding with further
309 * computation of keys. Parameters which were not sent are simply
310 * omitted from the concatenation process. The resulting two vectors
311 * are called the two key vectors.
312 */
313
314 local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
315 peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
316
317 if (!peer_key_vector || !local_key_vector)
318 goto out;
319
320 /* Figure out the order in wich the key_vectors will be
321 * added to the endpoint shared key.
322 * SCTP-AUTH, Section 6.1:
323 * This is performed by selecting the numerically smaller key
324 * vector and concatenating it to the endpoint pair shared
325 * key, and then concatenating the numerically larger key
326 * vector to that. If the key vectors are equal as numbers
327 * but differ in length, then the concatenation order is the
328 * endpoint shared key, followed by the shorter key vector,
329 * followed by the longer key vector. Otherwise, the key
330 * vectors are identical, and may be concatenated to the
331 * endpoint pair key in any order.
332 */
333 cmp = sctp_auth_compare_vectors(local_key_vector,
334 peer_key_vector);
335 if (cmp < 0) {
336 first_vector = local_key_vector;
337 last_vector = peer_key_vector;
338 } else {
339 first_vector = peer_key_vector;
340 last_vector = local_key_vector;
341 }
342
343 secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
344 gfp);
345out:
346 kfree(local_key_vector);
347 kfree(peer_key_vector);
348
349 return secret;
350}
351
352/*
353 * Populate the association overlay list with the list
354 * from the endpoint.
355 */
356int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
357 struct sctp_association *asoc,
358 gfp_t gfp)
359{
360 struct sctp_shared_key *sh_key;
361 struct sctp_shared_key *new;
362
363 BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
364
365 key_for_each(sh_key, &ep->endpoint_shared_keys) {
366 new = sctp_auth_shkey_create(sh_key->key_id, gfp);
367 if (!new)
368 goto nomem;
369
370 new->key = sh_key->key;
371 sctp_auth_key_hold(new->key);
372 list_add(&new->key_list, &asoc->endpoint_shared_keys);
373 }
374
375 return 0;
376
377nomem:
378 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
379 return -ENOMEM;
380}
381
382
383/* Public interface to creat the association shared key.
384 * See code above for the algorithm.
385 */
386int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
387{
388 struct sctp_auth_bytes *secret;
389 struct sctp_shared_key *ep_key;
390
391 /* If we don't support AUTH, or peer is not capable
392 * we don't need to do anything.
393 */
394 if (!sctp_auth_enable || !asoc->peer.auth_capable)
395 return 0;
396
397 /* If the key_id is non-zero and we couldn't find an
398 * endpoint pair shared key, we can't compute the
399 * secret.
400 * For key_id 0, endpoint pair shared key is a NULL key.
401 */
402 ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
403 BUG_ON(!ep_key);
404
405 secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
406 if (!secret)
407 return -ENOMEM;
408
409 sctp_auth_key_put(asoc->asoc_shared_key);
410 asoc->asoc_shared_key = secret;
411
412 return 0;
413}
414
415
416/* Find the endpoint pair shared key based on the key_id */
417struct sctp_shared_key *sctp_auth_get_shkey(
418 const struct sctp_association *asoc,
419 __u16 key_id)
420{
421 struct sctp_shared_key *key = NULL;
422
423 /* First search associations set of endpoint pair shared keys */
424 key_for_each(key, &asoc->endpoint_shared_keys) {
425 if (key->key_id == key_id)
426 break;
427 }
428
429 return key;
430}
431
432/*
433 * Initialize all the possible digest transforms that we can use. Right now
434 * now, the supported digests are SHA1 and SHA256. We do this here once
435 * because of the restrictiong that transforms may only be allocated in
436 * user context. This forces us to pre-allocated all possible transforms
437 * at the endpoint init time.
438 */
439int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
440{
441 struct crypto_hash *tfm = NULL;
442 __u16 id;
443
444 /* if the transforms are already allocted, we are done */
445 if (!sctp_auth_enable) {
446 ep->auth_hmacs = NULL;
447 return 0;
448 }
449
450 if (ep->auth_hmacs)
451 return 0;
452
453 /* Allocated the array of pointers to transorms */
454 ep->auth_hmacs = kzalloc(
455 sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
456 gfp);
457 if (!ep->auth_hmacs)
458 return -ENOMEM;
459
460 for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
461
462 /* See is we support the id. Supported IDs have name and
463 * length fields set, so that we can allocated and use
464 * them. We can safely just check for name, for without the
465 * name, we can't allocate the TFM.
466 */
467 if (!sctp_hmac_list[id].hmac_name)
468 continue;
469
470 /* If this TFM has been allocated, we are all set */
471 if (ep->auth_hmacs[id])
472 continue;
473
474 /* Allocate the ID */
475 tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
476 CRYPTO_ALG_ASYNC);
477 if (IS_ERR(tfm))
478 goto out_err;
479
480 ep->auth_hmacs[id] = tfm;
481 }
482
483 return 0;
484
485out_err:
486 /* Clean up any successfull allocations */
487 sctp_auth_destroy_hmacs(ep->auth_hmacs);
488 return -ENOMEM;
489}
490
491/* Destroy the hmac tfm array */
492void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
493{
494 int i;
495
496 if (!auth_hmacs)
497 return;
498
499 for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++)
500 {
501 if (auth_hmacs[i])
502 crypto_free_hash(auth_hmacs[i]);
503 }
504 kfree(auth_hmacs);
505}
506
507
508struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
509{
510 return &sctp_hmac_list[hmac_id];
511}
512
513/* Get an hmac description information that we can use to build
514 * the AUTH chunk
515 */
516struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
517{
518 struct sctp_hmac_algo_param *hmacs;
519 __u16 n_elt;
520 __u16 id = 0;
521 int i;
522
523 /* If we have a default entry, use it */
524 if (asoc->default_hmac_id)
525 return &sctp_hmac_list[asoc->default_hmac_id];
526
527 /* Since we do not have a default entry, find the first entry
528 * we support and return that. Do not cache that id.
529 */
530 hmacs = asoc->peer.peer_hmacs;
531 if (!hmacs)
532 return NULL;
533
534 n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
535 for (i = 0; i < n_elt; i++) {
536 id = ntohs(hmacs->hmac_ids[i]);
537
538 /* Check the id is in the supported range */
539 if (id > SCTP_AUTH_HMAC_ID_MAX)
540 continue;
541
542 /* See is we support the id. Supported IDs have name and
543 * length fields set, so that we can allocated and use
544 * them. We can safely just check for name, for without the
545 * name, we can't allocate the TFM.
546 */
547 if (!sctp_hmac_list[id].hmac_name)
548 continue;
549
550 break;
551 }
552
553 if (id == 0)
554 return NULL;
555
556 return &sctp_hmac_list[id];
557}
558
559static int __sctp_auth_find_hmacid(__u16 *hmacs, int n_elts, __u16 hmac_id)
560{
561 int found = 0;
562 int i;
563
564 for (i = 0; i < n_elts; i++) {
565 if (hmac_id == hmacs[i]) {
566 found = 1;
567 break;
568 }
569 }
570
571 return found;
572}
573
574/* See if the HMAC_ID is one that we claim as supported */
575int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
576 __u16 hmac_id)
577{
578 struct sctp_hmac_algo_param *hmacs;
579 __u16 n_elt;
580
581 if (!asoc)
582 return 0;
583
584 hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
585 n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
586
587 return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
588}
589
590
591/* Cache the default HMAC id. This to follow this text from SCTP-AUTH:
592 * Section 6.1:
593 * The receiver of a HMAC-ALGO parameter SHOULD use the first listed
594 * algorithm it supports.
595 */
596void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
597 struct sctp_hmac_algo_param *hmacs)
598{
599 struct sctp_endpoint *ep;
600 __u16 id;
601 int i;
602 int n_params;
603
604 /* if the default id is already set, use it */
605 if (asoc->default_hmac_id)
606 return;
607
608 n_params = (ntohs(hmacs->param_hdr.length)
609 - sizeof(sctp_paramhdr_t)) >> 1;
610 ep = asoc->ep;
611 for (i = 0; i < n_params; i++) {
612 id = ntohs(hmacs->hmac_ids[i]);
613
614 /* Check the id is in the supported range */
615 if (id > SCTP_AUTH_HMAC_ID_MAX)
616 continue;
617
618 /* If this TFM has been allocated, use this id */
619 if (ep->auth_hmacs[id]) {
620 asoc->default_hmac_id = id;
621 break;
622 }
623 }
624}
625
626
627/* Check to see if the given chunk is supposed to be authenticated */
628static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
629{
630 unsigned short len;
631 int found = 0;
632 int i;
633
634 if (!param)
635 return 0;
636
637 len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);
638
639 /* SCTP-AUTH, Section 3.2
640 * The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
641 * chunks MUST NOT be listed in the CHUNKS parameter. However, if
642 * a CHUNKS parameter is received then the types for INIT, INIT-ACK,
643 * SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
644 */
645 for (i = 0; !found && i < len; i++) {
646 switch (param->chunks[i]) {
647 case SCTP_CID_INIT:
648 case SCTP_CID_INIT_ACK:
649 case SCTP_CID_SHUTDOWN_COMPLETE:
650 case SCTP_CID_AUTH:
651 break;
652
653 default:
654 if (param->chunks[i] == chunk)
655 found = 1;
656 break;
657 }
658 }
659
660 return found;
661}
662
663/* Check if peer requested that this chunk is authenticated */
664int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
665{
666 if (!sctp_auth_enable || !asoc || !asoc->peer.auth_capable)
667 return 0;
668
669 return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
670}
671
672/* Check if we requested that peer authenticate this chunk. */
673int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
674{
675 if (!sctp_auth_enable || !asoc)
676 return 0;
677
678 return __sctp_auth_cid(chunk,
679 (struct sctp_chunks_param *)asoc->c.auth_chunks);
680}
681
682/* SCTP-AUTH: Section 6.2:
683 * The sender MUST calculate the MAC as described in RFC2104 [2] using
684 * the hash function H as described by the MAC Identifier and the shared
685 * association key K based on the endpoint pair shared key described by
686 * the shared key identifier. The 'data' used for the computation of
687 * the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
688 * zero (as shown in Figure 6) followed by all chunks that are placed
689 * after the AUTH chunk in the SCTP packet.
690 */
691void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
692 struct sk_buff *skb,
693 struct sctp_auth_chunk *auth,
694 gfp_t gfp)
695{
696 struct scatterlist sg;
697 struct hash_desc desc;
698 struct sctp_auth_bytes *asoc_key;
699 __u16 key_id, hmac_id;
700 __u8 *digest;
701 unsigned char *end;
702 int free_key = 0;
703
704 /* Extract the info we need:
705 * - hmac id
706 * - key id
707 */
708 key_id = ntohs(auth->auth_hdr.shkey_id);
709 hmac_id = ntohs(auth->auth_hdr.hmac_id);
710
711 if (key_id == asoc->active_key_id)
712 asoc_key = asoc->asoc_shared_key;
713 else {
714 struct sctp_shared_key *ep_key;
715
716 ep_key = sctp_auth_get_shkey(asoc, key_id);
717 if (!ep_key)
718 return;
719
720 asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
721 if (!asoc_key)
722 return;
723
724 free_key = 1;
725 }
726
727 /* set up scatter list */
728 end = skb_tail_pointer(skb);
729 sg.page = virt_to_page(auth);
730 sg.offset = (unsigned long)(auth) % PAGE_SIZE;
731 sg.length = end - (unsigned char *)auth;
732
733 desc.tfm = asoc->ep->auth_hmacs[hmac_id];
734 desc.flags = 0;
735
736 digest = auth->auth_hdr.hmac;
737 if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
738 goto free;
739
740 crypto_hash_digest(&desc, &sg, sg.length, digest);
741
742free:
743 if (free_key)
744 sctp_auth_key_put(asoc_key);
745}