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