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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 creat 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 
392         /* If we don't support AUTH, or peer is not capable
393          * we don't need to do anything.
394          */
395         if (!asoc->ep->auth_enable || !asoc->peer.auth_capable)
396                 return 0;
397 
398         /* If the key_id is non-zero and we couldn't find an
399          * endpoint pair shared key, we can't compute the
400          * secret.
401          * For key_id 0, endpoint pair shared key is a NULL key.
402          */
403         ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
404         BUG_ON(!ep_key);
405 
406         secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
407         if (!secret)
408                 return -ENOMEM;
409 
410         sctp_auth_key_put(asoc->asoc_shared_key);
411         asoc->asoc_shared_key = secret;
412 
413         return 0;
414 }
415 
416 
417 /* Find the endpoint pair shared key based on the key_id */
418 struct sctp_shared_key *sctp_auth_get_shkey(
419                                 const struct sctp_association *asoc,
420                                 __u16 key_id)
421 {
422         struct sctp_shared_key *key;
423 
424         /* First search associations set of endpoint pair shared keys */
425         key_for_each(key, &asoc->endpoint_shared_keys) {
426                 if (key->key_id == key_id)
427                         return key;
428         }
429 
430         return NULL;
431 }
432 
433 /*
434  * Initialize all the possible digest transforms that we can use.  Right now
435  * now, the supported digests are SHA1 and SHA256.  We do this here once
436  * because of the restrictiong that transforms may only be allocated in
437  * user context.  This forces us to pre-allocated all possible transforms
438  * at the endpoint init time.
439  */
440 int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
441 {
442         struct crypto_hash *tfm = NULL;
443         __u16   id;
444 
445         /* If AUTH extension is disabled, we are done */
446         if (!ep->auth_enable) {
447                 ep->auth_hmacs = NULL;
448                 return 0;
449         }
450 
451         /* If the transforms are already allocated, we are done */
452         if (ep->auth_hmacs)
453                 return 0;
454 
455         /* Allocated the array of pointers to transorms */
456         ep->auth_hmacs = kzalloc(
457                             sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
458                             gfp);
459         if (!ep->auth_hmacs)
460                 return -ENOMEM;
461 
462         for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
463 
464                 /* See is we support the id.  Supported IDs have name and
465                  * length fields set, so that we can allocated and use
466                  * them.  We can safely just check for name, for without the
467                  * name, we can't allocate the TFM.
468                  */
469                 if (!sctp_hmac_list[id].hmac_name)
470                         continue;
471 
472                 /* If this TFM has been allocated, we are all set */
473                 if (ep->auth_hmacs[id])
474                         continue;
475 
476                 /* Allocate the ID */
477                 tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
478                                         CRYPTO_ALG_ASYNC);
479                 if (IS_ERR(tfm))
480                         goto out_err;
481 
482                 ep->auth_hmacs[id] = tfm;
483         }
484 
485         return 0;
486 
487 out_err:
488         /* Clean up any successful allocations */
489         sctp_auth_destroy_hmacs(ep->auth_hmacs);
490         return -ENOMEM;
491 }
492 
493 /* Destroy the hmac tfm array */
494 void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
495 {
496         int i;
497 
498         if (!auth_hmacs)
499                 return;
500 
501         for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++) {
502                 if (auth_hmacs[i])
503                         crypto_free_hash(auth_hmacs[i]);
504         }
505         kfree(auth_hmacs);
506 }
507 
508 
509 struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
510 {
511         return &sctp_hmac_list[hmac_id];
512 }
513 
514 /* Get an hmac description information that we can use to build
515  * the AUTH chunk
516  */
517 struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
518 {
519         struct sctp_hmac_algo_param *hmacs;
520         __u16 n_elt;
521         __u16 id = 0;
522         int i;
523 
524         /* If we have a default entry, use it */
525         if (asoc->default_hmac_id)
526                 return &sctp_hmac_list[asoc->default_hmac_id];
527 
528         /* Since we do not have a default entry, find the first entry
529          * we support and return that.  Do not cache that id.
530          */
531         hmacs = asoc->peer.peer_hmacs;
532         if (!hmacs)
533                 return NULL;
534 
535         n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
536         for (i = 0; i < n_elt; i++) {
537                 id = ntohs(hmacs->hmac_ids[i]);
538 
539                 /* Check the id is in the supported range. And
540                  * see if we support the id.  Supported IDs have name and
541                  * length fields set, so that we can allocate and use
542                  * them.  We can safely just check for name, for without the
543                  * name, we can't allocate the TFM.
544                  */
545                 if (id > SCTP_AUTH_HMAC_ID_MAX ||
546                     !sctp_hmac_list[id].hmac_name) {
547                         id = 0;
548                         continue;
549                 }
550 
551                 break;
552         }
553 
554         if (id == 0)
555                 return NULL;
556 
557         return &sctp_hmac_list[id];
558 }
559 
560 static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
561 {
562         int  found = 0;
563         int  i;
564 
565         for (i = 0; i < n_elts; i++) {
566                 if (hmac_id == hmacs[i]) {
567                         found = 1;
568                         break;
569                 }
570         }
571 
572         return found;
573 }
574 
575 /* See if the HMAC_ID is one that we claim as supported */
576 int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
577                                     __be16 hmac_id)
578 {
579         struct sctp_hmac_algo_param *hmacs;
580         __u16 n_elt;
581 
582         if (!asoc)
583                 return 0;
584 
585         hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
586         n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
587 
588         return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
589 }
590 
591 
592 /* Cache the default HMAC id.  This to follow this text from SCTP-AUTH:
593  * Section 6.1:
594  *   The receiver of a HMAC-ALGO parameter SHOULD use the first listed
595  *   algorithm it supports.
596  */
597 void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
598                                      struct sctp_hmac_algo_param *hmacs)
599 {
600         struct sctp_endpoint *ep;
601         __u16   id;
602         int     i;
603         int     n_params;
604 
605         /* if the default id is already set, use it */
606         if (asoc->default_hmac_id)
607                 return;
608 
609         n_params = (ntohs(hmacs->param_hdr.length)
610                                 - sizeof(sctp_paramhdr_t)) >> 1;
611         ep = asoc->ep;
612         for (i = 0; i < n_params; i++) {
613                 id = ntohs(hmacs->hmac_ids[i]);
614 
615                 /* Check the id is in the supported range */
616                 if (id > SCTP_AUTH_HMAC_ID_MAX)
617                         continue;
618 
619                 /* If this TFM has been allocated, use this id */
620                 if (ep->auth_hmacs[id]) {
621                         asoc->default_hmac_id = id;
622                         break;
623                 }
624         }
625 }
626 
627 
628 /* Check to see if the given chunk is supposed to be authenticated */
629 static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
630 {
631         unsigned short len;
632         int found = 0;
633         int i;
634 
635         if (!param || param->param_hdr.length == 0)
636                 return 0;
637 
638         len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);
639 
640         /* SCTP-AUTH, Section 3.2
641          *    The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
642          *    chunks MUST NOT be listed in the CHUNKS parameter.  However, if
643          *    a CHUNKS parameter is received then the types for INIT, INIT-ACK,
644          *    SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
645          */
646         for (i = 0; !found && i < len; i++) {
647                 switch (param->chunks[i]) {
648                 case SCTP_CID_INIT:
649                 case SCTP_CID_INIT_ACK:
650                 case SCTP_CID_SHUTDOWN_COMPLETE:
651                 case SCTP_CID_AUTH:
652                         break;
653 
654                 default:
655                         if (param->chunks[i] == chunk)
656                                 found = 1;
657                         break;
658                 }
659         }
660 
661         return found;
662 }
663 
664 /* Check if peer requested that this chunk is authenticated */
665 int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
666 {
667         if (!asoc)
668                 return 0;
669 
670         if (!asoc->ep->auth_enable || !asoc->peer.auth_capable)
671                 return 0;
672 
673         return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
674 }
675 
676 /* Check if we requested that peer authenticate this chunk. */
677 int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
678 {
679         if (!asoc)
680                 return 0;
681 
682         if (!asoc->ep->auth_enable)
683                 return 0;
684 
685         return __sctp_auth_cid(chunk,
686                               (struct sctp_chunks_param *)asoc->c.auth_chunks);
687 }
688 
689 /* SCTP-AUTH: Section 6.2:
690  *    The sender MUST calculate the MAC as described in RFC2104 [2] using
691  *    the hash function H as described by the MAC Identifier and the shared
692  *    association key K based on the endpoint pair shared key described by
693  *    the shared key identifier.  The 'data' used for the computation of
694  *    the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
695  *    zero (as shown in Figure 6) followed by all chunks that are placed
696  *    after the AUTH chunk in the SCTP packet.
697  */
698 void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
699                               struct sk_buff *skb,
700                               struct sctp_auth_chunk *auth,
701                               gfp_t gfp)
702 {
703         struct scatterlist sg;
704         struct hash_desc desc;
705         struct sctp_auth_bytes *asoc_key;
706         __u16 key_id, hmac_id;
707         __u8 *digest;
708         unsigned char *end;
709         int free_key = 0;
710 
711         /* Extract the info we need:
712          * - hmac id
713          * - key id
714          */
715         key_id = ntohs(auth->auth_hdr.shkey_id);
716         hmac_id = ntohs(auth->auth_hdr.hmac_id);
717 
718         if (key_id == asoc->active_key_id)
719                 asoc_key = asoc->asoc_shared_key;
720         else {
721                 struct sctp_shared_key *ep_key;
722 
723                 ep_key = sctp_auth_get_shkey(asoc, key_id);
724                 if (!ep_key)
725                         return;
726 
727                 asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
728                 if (!asoc_key)
729                         return;
730 
731                 free_key = 1;
732         }
733 
734         /* set up scatter list */
735         end = skb_tail_pointer(skb);
736         sg_init_one(&sg, auth, end - (unsigned char *)auth);
737 
738         desc.tfm = asoc->ep->auth_hmacs[hmac_id];
739         desc.flags = 0;
740 
741         digest = auth->auth_hdr.hmac;
742         if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
743                 goto free;
744 
745         crypto_hash_digest(&desc, &sg, sg.length, digest);
746 
747 free:
748         if (free_key)
749                 sctp_auth_key_put(asoc_key);
750 }
751 
752 /* API Helpers */
753 
754 /* Add a chunk to the endpoint authenticated chunk list */
755 int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
756 {
757         struct sctp_chunks_param *p = ep->auth_chunk_list;
758         __u16 nchunks;
759         __u16 param_len;
760 
761         /* If this chunk is already specified, we are done */
762         if (__sctp_auth_cid(chunk_id, p))
763                 return 0;
764 
765         /* Check if we can add this chunk to the array */
766         param_len = ntohs(p->param_hdr.length);
767         nchunks = param_len - sizeof(sctp_paramhdr_t);
768         if (nchunks == SCTP_NUM_CHUNK_TYPES)
769                 return -EINVAL;
770 
771         p->chunks[nchunks] = chunk_id;
772         p->param_hdr.length = htons(param_len + 1);
773         return 0;
774 }
775 
776 /* Add hmac identifires to the endpoint list of supported hmac ids */
777 int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
778                            struct sctp_hmacalgo *hmacs)
779 {
780         int has_sha1 = 0;
781         __u16 id;
782         int i;
783 
784         /* Scan the list looking for unsupported id.  Also make sure that
785          * SHA1 is specified.
786          */
787         for (i = 0; i < hmacs->shmac_num_idents; i++) {
788                 id = hmacs->shmac_idents[i];
789 
790                 if (id > SCTP_AUTH_HMAC_ID_MAX)
791                         return -EOPNOTSUPP;
792 
793                 if (SCTP_AUTH_HMAC_ID_SHA1 == id)
794                         has_sha1 = 1;
795 
796                 if (!sctp_hmac_list[id].hmac_name)
797                         return -EOPNOTSUPP;
798         }
799 
800         if (!has_sha1)
801                 return -EINVAL;
802 
803         for (i = 0; i < hmacs->shmac_num_idents; i++)
804                 ep->auth_hmacs_list->hmac_ids[i] = htons(hmacs->shmac_idents[i]);
805         ep->auth_hmacs_list->param_hdr.length = htons(sizeof(sctp_paramhdr_t) +
806                                 hmacs->shmac_num_idents * sizeof(__u16));
807         return 0;
808 }
809 
810 /* Set a new shared key on either endpoint or association.  If the
811  * the key with a same ID already exists, replace the key (remove the
812  * old key and add a new one).
813  */
814 int sctp_auth_set_key(struct sctp_endpoint *ep,
815                       struct sctp_association *asoc,
816                       struct sctp_authkey *auth_key)
817 {
818         struct sctp_shared_key *cur_key = NULL;
819         struct sctp_auth_bytes *key;
820         struct list_head *sh_keys;
821         int replace = 0;
822 
823         /* Try to find the given key id to see if
824          * we are doing a replace, or adding a new key
825          */
826         if (asoc)
827                 sh_keys = &asoc->endpoint_shared_keys;
828         else
829                 sh_keys = &ep->endpoint_shared_keys;
830 
831         key_for_each(cur_key, sh_keys) {
832                 if (cur_key->key_id == auth_key->sca_keynumber) {
833                         replace = 1;
834                         break;
835                 }
836         }
837 
838         /* If we are not replacing a key id, we need to allocate
839          * a shared key.
840          */
841         if (!replace) {
842                 cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber,
843                                                  GFP_KERNEL);
844                 if (!cur_key)
845                         return -ENOMEM;
846         }
847 
848         /* Create a new key data based on the info passed in */
849         key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
850         if (!key)
851                 goto nomem;
852 
853         memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);
854 
855         /* If we are replacing, remove the old keys data from the
856          * key id.  If we are adding new key id, add it to the
857          * list.
858          */
859         if (replace)
860                 sctp_auth_key_put(cur_key->key);
861         else
862                 list_add(&cur_key->key_list, sh_keys);
863 
864         cur_key->key = key;
865         return 0;
866 nomem:
867         if (!replace)
868                 sctp_auth_shkey_free(cur_key);
869 
870         return -ENOMEM;
871 }
872 
873 int sctp_auth_set_active_key(struct sctp_endpoint *ep,
874                              struct sctp_association *asoc,
875                              __u16  key_id)
876 {
877         struct sctp_shared_key *key;
878         struct list_head *sh_keys;
879         int found = 0;
880 
881         /* The key identifier MUST correst to an existing key */
882         if (asoc)
883                 sh_keys = &asoc->endpoint_shared_keys;
884         else
885                 sh_keys = &ep->endpoint_shared_keys;
886 
887         key_for_each(key, sh_keys) {
888                 if (key->key_id == key_id) {
889                         found = 1;
890                         break;
891                 }
892         }
893 
894         if (!found)
895                 return -EINVAL;
896 
897         if (asoc) {
898                 asoc->active_key_id = key_id;
899                 sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL);
900         } else
901                 ep->active_key_id = key_id;
902 
903         return 0;
904 }
905 
906 int sctp_auth_del_key_id(struct sctp_endpoint *ep,
907                          struct sctp_association *asoc,
908                          __u16  key_id)
909 {
910         struct sctp_shared_key *key;
911         struct list_head *sh_keys;
912         int found = 0;
913 
914         /* The key identifier MUST NOT be the current active key
915          * The key identifier MUST correst to an existing key
916          */
917         if (asoc) {
918                 if (asoc->active_key_id == key_id)
919                         return -EINVAL;
920 
921                 sh_keys = &asoc->endpoint_shared_keys;
922         } else {
923                 if (ep->active_key_id == key_id)
924                         return -EINVAL;
925 
926                 sh_keys = &ep->endpoint_shared_keys;
927         }
928 
929         key_for_each(key, sh_keys) {
930                 if (key->key_id == key_id) {
931                         found = 1;
932                         break;
933                 }
934         }
935 
936         if (!found)
937                 return -EINVAL;
938 
939         /* Delete the shared key */
940         list_del_init(&key->key_list);
941         sctp_auth_shkey_free(key);
942 
943         return 0;
944 }
945 

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