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TOMOYO Linux Cross Reference
Linux/net/sctp/auth.c

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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 
 37 static 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 
 61 void 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 */
 73 static 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 */
 94 struct 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 */
110 static 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  */
121 void 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  */
151 static 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  */
187 static 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 */
224 static 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 */
236 static 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  */
256 static 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  */
290 static 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);
346 out:
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  */
357 int 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 
378 nomem:
379         sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
380         return -ENOMEM;
381 }
382 
383 
384 /* Public interface to create the association shared key.
385  * See code above for the algorithm.
386  */
387 int 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         struct sctp_chunk *chunk;
392 
393         /* If we don't support AUTH, or peer is not capable
394          * we don't need to do anything.
395          */
396         if (!asoc->ep->auth_enable || !asoc->peer.auth_capable)
397                 return 0;
398 
399         /* If the key_id is non-zero and we couldn't find an
400          * endpoint pair shared key, we can't compute the
401          * secret.
402          * For key_id 0, endpoint pair shared key is a NULL key.
403          */
404         ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
405         BUG_ON(!ep_key);
406 
407         secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
408         if (!secret)
409                 return -ENOMEM;
410 
411         sctp_auth_key_put(asoc->asoc_shared_key);
412         asoc->asoc_shared_key = secret;
413 
414         /* Update send queue in case any chunk already in there now
415          * needs authenticating
416          */
417         list_for_each_entry(chunk, &asoc->outqueue.out_chunk_list, list) {
418                 if (sctp_auth_send_cid(chunk->chunk_hdr->type, asoc))
419                         chunk->auth = 1;
420         }
421 
422         return 0;
423 }
424 
425 
426 /* Find the endpoint pair shared key based on the key_id */
427 struct sctp_shared_key *sctp_auth_get_shkey(
428                                 const struct sctp_association *asoc,
429                                 __u16 key_id)
430 {
431         struct sctp_shared_key *key;
432 
433         /* First search associations set of endpoint pair shared keys */
434         key_for_each(key, &asoc->endpoint_shared_keys) {
435                 if (key->key_id == key_id)
436                         return key;
437         }
438 
439         return NULL;
440 }
441 
442 /*
443  * Initialize all the possible digest transforms that we can use.  Right now
444  * now, the supported digests are SHA1 and SHA256.  We do this here once
445  * because of the restrictiong that transforms may only be allocated in
446  * user context.  This forces us to pre-allocated all possible transforms
447  * at the endpoint init time.
448  */
449 int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
450 {
451         struct crypto_hash *tfm = NULL;
452         __u16   id;
453 
454         /* If AUTH extension is disabled, we are done */
455         if (!ep->auth_enable) {
456                 ep->auth_hmacs = NULL;
457                 return 0;
458         }
459 
460         /* If the transforms are already allocated, we are done */
461         if (ep->auth_hmacs)
462                 return 0;
463 
464         /* Allocated the array of pointers to transorms */
465         ep->auth_hmacs = kzalloc(
466                             sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
467                             gfp);
468         if (!ep->auth_hmacs)
469                 return -ENOMEM;
470 
471         for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
472 
473                 /* See is we support the id.  Supported IDs have name and
474                  * length fields set, so that we can allocated and use
475                  * them.  We can safely just check for name, for without the
476                  * name, we can't allocate the TFM.
477                  */
478                 if (!sctp_hmac_list[id].hmac_name)
479                         continue;
480 
481                 /* If this TFM has been allocated, we are all set */
482                 if (ep->auth_hmacs[id])
483                         continue;
484 
485                 /* Allocate the ID */
486                 tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
487                                         CRYPTO_ALG_ASYNC);
488                 if (IS_ERR(tfm))
489                         goto out_err;
490 
491                 ep->auth_hmacs[id] = tfm;
492         }
493 
494         return 0;
495 
496 out_err:
497         /* Clean up any successful allocations */
498         sctp_auth_destroy_hmacs(ep->auth_hmacs);
499         return -ENOMEM;
500 }
501 
502 /* Destroy the hmac tfm array */
503 void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
504 {
505         int i;
506 
507         if (!auth_hmacs)
508                 return;
509 
510         for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++) {
511                 if (auth_hmacs[i])
512                         crypto_free_hash(auth_hmacs[i]);
513         }
514         kfree(auth_hmacs);
515 }
516 
517 
518 struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
519 {
520         return &sctp_hmac_list[hmac_id];
521 }
522 
523 /* Get an hmac description information that we can use to build
524  * the AUTH chunk
525  */
526 struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
527 {
528         struct sctp_hmac_algo_param *hmacs;
529         __u16 n_elt;
530         __u16 id = 0;
531         int i;
532 
533         /* If we have a default entry, use it */
534         if (asoc->default_hmac_id)
535                 return &sctp_hmac_list[asoc->default_hmac_id];
536 
537         /* Since we do not have a default entry, find the first entry
538          * we support and return that.  Do not cache that id.
539          */
540         hmacs = asoc->peer.peer_hmacs;
541         if (!hmacs)
542                 return NULL;
543 
544         n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
545         for (i = 0; i < n_elt; i++) {
546                 id = ntohs(hmacs->hmac_ids[i]);
547 
548                 /* Check the id is in the supported range. And
549                  * see if we support the id.  Supported IDs have name and
550                  * length fields set, so that we can allocate and use
551                  * them.  We can safely just check for name, for without the
552                  * name, we can't allocate the TFM.
553                  */
554                 if (id > SCTP_AUTH_HMAC_ID_MAX ||
555                     !sctp_hmac_list[id].hmac_name) {
556                         id = 0;
557                         continue;
558                 }
559 
560                 break;
561         }
562 
563         if (id == 0)
564                 return NULL;
565 
566         return &sctp_hmac_list[id];
567 }
568 
569 static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
570 {
571         int  found = 0;
572         int  i;
573 
574         for (i = 0; i < n_elts; i++) {
575                 if (hmac_id == hmacs[i]) {
576                         found = 1;
577                         break;
578                 }
579         }
580 
581         return found;
582 }
583 
584 /* See if the HMAC_ID is one that we claim as supported */
585 int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
586                                     __be16 hmac_id)
587 {
588         struct sctp_hmac_algo_param *hmacs;
589         __u16 n_elt;
590 
591         if (!asoc)
592                 return 0;
593 
594         hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
595         n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 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  */
606 void 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(sctp_paramhdr_t)) >> 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 */
638 static int __sctp_auth_cid(sctp_cid_t 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(sctp_paramhdr_t);
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 */
674 int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
675 {
676         if (!asoc)
677                 return 0;
678 
679         if (!asoc->ep->auth_enable || !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. */
686 int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
687 {
688         if (!asoc)
689                 return 0;
690 
691         if (!asoc->ep->auth_enable)
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  */
707 void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
708                               struct sk_buff *skb,
709                               struct sctp_auth_chunk *auth,
710                               gfp_t gfp)
711 {
712         struct scatterlist sg;
713         struct hash_desc desc;
714         struct sctp_auth_bytes *asoc_key;
715         __u16 key_id, hmac_id;
716         __u8 *digest;
717         unsigned char *end;
718         int free_key = 0;
719 
720         /* Extract the info we need:
721          * - hmac id
722          * - key id
723          */
724         key_id = ntohs(auth->auth_hdr.shkey_id);
725         hmac_id = ntohs(auth->auth_hdr.hmac_id);
726 
727         if (key_id == asoc->active_key_id)
728                 asoc_key = asoc->asoc_shared_key;
729         else {
730                 struct sctp_shared_key *ep_key;
731 
732                 ep_key = sctp_auth_get_shkey(asoc, key_id);
733                 if (!ep_key)
734                         return;
735 
736                 asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
737                 if (!asoc_key)
738                         return;
739 
740                 free_key = 1;
741         }
742 
743         /* set up scatter list */
744         end = skb_tail_pointer(skb);
745         sg_init_one(&sg, auth, end - (unsigned char *)auth);
746 
747         desc.tfm = asoc->ep->auth_hmacs[hmac_id];
748         desc.flags = 0;
749 
750         digest = auth->auth_hdr.hmac;
751         if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
752                 goto free;
753 
754         crypto_hash_digest(&desc, &sg, sg.length, digest);
755 
756 free:
757         if (free_key)
758                 sctp_auth_key_put(asoc_key);
759 }
760 
761 /* API Helpers */
762 
763 /* Add a chunk to the endpoint authenticated chunk list */
764 int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
765 {
766         struct sctp_chunks_param *p = ep->auth_chunk_list;
767         __u16 nchunks;
768         __u16 param_len;
769 
770         /* If this chunk is already specified, we are done */
771         if (__sctp_auth_cid(chunk_id, p))
772                 return 0;
773 
774         /* Check if we can add this chunk to the array */
775         param_len = ntohs(p->param_hdr.length);
776         nchunks = param_len - sizeof(sctp_paramhdr_t);
777         if (nchunks == SCTP_NUM_CHUNK_TYPES)
778                 return -EINVAL;
779 
780         p->chunks[nchunks] = chunk_id;
781         p->param_hdr.length = htons(param_len + 1);
782         return 0;
783 }
784 
785 /* Add hmac identifires to the endpoint list of supported hmac ids */
786 int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
787                            struct sctp_hmacalgo *hmacs)
788 {
789         int has_sha1 = 0;
790         __u16 id;
791         int i;
792 
793         /* Scan the list looking for unsupported id.  Also make sure that
794          * SHA1 is specified.
795          */
796         for (i = 0; i < hmacs->shmac_num_idents; i++) {
797                 id = hmacs->shmac_idents[i];
798 
799                 if (id > SCTP_AUTH_HMAC_ID_MAX)
800                         return -EOPNOTSUPP;
801 
802                 if (SCTP_AUTH_HMAC_ID_SHA1 == id)
803                         has_sha1 = 1;
804 
805                 if (!sctp_hmac_list[id].hmac_name)
806                         return -EOPNOTSUPP;
807         }
808 
809         if (!has_sha1)
810                 return -EINVAL;
811 
812         for (i = 0; i < hmacs->shmac_num_idents; i++)
813                 ep->auth_hmacs_list->hmac_ids[i] = htons(hmacs->shmac_idents[i]);
814         ep->auth_hmacs_list->param_hdr.length = htons(sizeof(sctp_paramhdr_t) +
815                                 hmacs->shmac_num_idents * sizeof(__u16));
816         return 0;
817 }
818 
819 /* Set a new shared key on either endpoint or association.  If the
820  * the key with a same ID already exists, replace the key (remove the
821  * old key and add a new one).
822  */
823 int sctp_auth_set_key(struct sctp_endpoint *ep,
824                       struct sctp_association *asoc,
825                       struct sctp_authkey *auth_key)
826 {
827         struct sctp_shared_key *cur_key = NULL;
828         struct sctp_auth_bytes *key;
829         struct list_head *sh_keys;
830         int replace = 0;
831 
832         /* Try to find the given key id to see if
833          * we are doing a replace, or adding a new key
834          */
835         if (asoc)
836                 sh_keys = &asoc->endpoint_shared_keys;
837         else
838                 sh_keys = &ep->endpoint_shared_keys;
839 
840         key_for_each(cur_key, sh_keys) {
841                 if (cur_key->key_id == auth_key->sca_keynumber) {
842                         replace = 1;
843                         break;
844                 }
845         }
846 
847         /* If we are not replacing a key id, we need to allocate
848          * a shared key.
849          */
850         if (!replace) {
851                 cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber,
852                                                  GFP_KERNEL);
853                 if (!cur_key)
854                         return -ENOMEM;
855         }
856 
857         /* Create a new key data based on the info passed in */
858         key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
859         if (!key)
860                 goto nomem;
861 
862         memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);
863 
864         /* If we are replacing, remove the old keys data from the
865          * key id.  If we are adding new key id, add it to the
866          * list.
867          */
868         if (replace)
869                 sctp_auth_key_put(cur_key->key);
870         else
871                 list_add(&cur_key->key_list, sh_keys);
872 
873         cur_key->key = key;
874         return 0;
875 nomem:
876         if (!replace)
877                 sctp_auth_shkey_free(cur_key);
878 
879         return -ENOMEM;
880 }
881 
882 int sctp_auth_set_active_key(struct sctp_endpoint *ep,
883                              struct sctp_association *asoc,
884                              __u16  key_id)
885 {
886         struct sctp_shared_key *key;
887         struct list_head *sh_keys;
888         int found = 0;
889 
890         /* The key identifier MUST correst to an existing key */
891         if (asoc)
892                 sh_keys = &asoc->endpoint_shared_keys;
893         else
894                 sh_keys = &ep->endpoint_shared_keys;
895 
896         key_for_each(key, sh_keys) {
897                 if (key->key_id == key_id) {
898                         found = 1;
899                         break;
900                 }
901         }
902 
903         if (!found)
904                 return -EINVAL;
905 
906         if (asoc) {
907                 asoc->active_key_id = key_id;
908                 sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL);
909         } else
910                 ep->active_key_id = key_id;
911 
912         return 0;
913 }
914 
915 int sctp_auth_del_key_id(struct sctp_endpoint *ep,
916                          struct sctp_association *asoc,
917                          __u16  key_id)
918 {
919         struct sctp_shared_key *key;
920         struct list_head *sh_keys;
921         int found = 0;
922 
923         /* The key identifier MUST NOT be the current active key
924          * The key identifier MUST correst to an existing key
925          */
926         if (asoc) {
927                 if (asoc->active_key_id == key_id)
928                         return -EINVAL;
929 
930                 sh_keys = &asoc->endpoint_shared_keys;
931         } else {
932                 if (ep->active_key_id == key_id)
933                         return -EINVAL;
934 
935                 sh_keys = &ep->endpoint_shared_keys;
936         }
937 
938         key_for_each(key, sh_keys) {
939                 if (key->key_id == key_id) {
940                         found = 1;
941                         break;
942                 }
943         }
944 
945         if (!found)
946                 return -EINVAL;
947 
948         /* Delete the shared key */
949         list_del_init(&key->key_list);
950         sctp_auth_shkey_free(key);
951 
952         return 0;
953 }
954 

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