linux/net/sctp/auth.c
<<
>>
Prefs
   1/* SCTP kernel implementation
   2 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
   3 *
   4 * This file is part of the SCTP kernel implementation
   5 *
   6 * This SCTP implementation is free software;
   7 * you can redistribute it and/or modify it under the terms of
   8 * the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2, or (at your option)
  10 * any later version.
  11 *
  12 * This SCTP implementation is distributed in the hope that it
  13 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  14 *                 ************************
  15 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  16 * See the GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with GNU CC; see the file COPYING.  If not, see
  20 * <http://www.gnu.org/licenses/>.
  21 *
  22 * Please send any bug reports or fixes you make to the
  23 * email address(es):
  24 *    lksctp developers <linux-sctp@vger.kernel.org>
  25 *
  26 * Written or modified by:
  27 *   Vlad Yasevich     <vladislav.yasevich@hp.com>
  28 */
  29
  30#include <linux/slab.h>
  31#include <linux/types.h>
  32#include <linux/crypto.h>
  33#include <linux/scatterlist.h>
  34#include <net/sctp/sctp.h>
  35#include <net/sctp/auth.h>
  36
  37static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
  38        {
  39                /* id 0 is reserved.  as all 0 */
  40                .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
  41        },
  42        {
  43                .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
  44                .hmac_name = "hmac(sha1)",
  45                .hmac_len = SCTP_SHA1_SIG_SIZE,
  46        },
  47        {
  48                /* id 2 is reserved as well */
  49                .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
  50        },
  51#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
  52        {
  53                .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
  54                .hmac_name = "hmac(sha256)",
  55                .hmac_len = SCTP_SHA256_SIG_SIZE,
  56        }
  57#endif
  58};
  59
  60
  61void sctp_auth_key_put(struct sctp_auth_bytes *key)
  62{
  63        if (!key)
  64                return;
  65
  66        if (atomic_dec_and_test(&key->refcnt)) {
  67                kzfree(key);
  68                SCTP_DBG_OBJCNT_DEC(keys);
  69        }
  70}
  71
  72/* Create a new key structure of a given length */
  73static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
  74{
  75        struct sctp_auth_bytes *key;
  76
  77        /* Verify that we are not going to overflow INT_MAX */
  78        if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
  79                return NULL;
  80
  81        /* Allocate the shared key */
  82        key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
  83        if (!key)
  84                return NULL;
  85
  86        key->len = key_len;
  87        atomic_set(&key->refcnt, 1);
  88        SCTP_DBG_OBJCNT_INC(keys);
  89
  90        return key;
  91}
  92
  93/* Create a new shared key container with a give key id */
  94struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
  95{
  96        struct sctp_shared_key *new;
  97
  98        /* Allocate the shared key container */
  99        new = kzalloc(sizeof(struct sctp_shared_key), gfp);
 100        if (!new)
 101                return NULL;
 102
 103        INIT_LIST_HEAD(&new->key_list);
 104        new->key_id = key_id;
 105
 106        return new;
 107}
 108
 109/* Free the shared key structure */
 110static void sctp_auth_shkey_free(struct sctp_shared_key *sh_key)
 111{
 112        BUG_ON(!list_empty(&sh_key->key_list));
 113        sctp_auth_key_put(sh_key->key);
 114        sh_key->key = NULL;
 115        kfree(sh_key);
 116}
 117
 118/* Destroy the entire key list.  This is done during the
 119 * associon and endpoint free process.
 120 */
 121void sctp_auth_destroy_keys(struct list_head *keys)
 122{
 123        struct sctp_shared_key *ep_key;
 124        struct sctp_shared_key *tmp;
 125
 126        if (list_empty(keys))
 127                return;
 128
 129        key_for_each_safe(ep_key, tmp, keys) {
 130                list_del_init(&ep_key->key_list);
 131                sctp_auth_shkey_free(ep_key);
 132        }
 133}
 134
 135/* Compare two byte vectors as numbers.  Return values
 136 * are:
 137 *        0 - vectors are equal
 138 *      < 0 - vector 1 is smaller than vector2
 139 *      > 0 - vector 1 is greater than vector2
 140 *
 141 * Algorithm is:
 142 *      This is performed by selecting the numerically smaller key vector...
 143 *      If the key vectors are equal as numbers but differ in length ...
 144 *      the shorter vector is considered smaller
 145 *
 146 * Examples (with small values):
 147 *      000123456789 > 123456789 (first number is longer)
 148 *      000123456789 < 234567891 (second number is larger numerically)
 149 *      123456789 > 2345678      (first number is both larger & longer)
 150 */
 151static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
 152                              struct sctp_auth_bytes *vector2)
 153{
 154        int diff;
 155        int i;
 156        const __u8 *longer;
 157
 158        diff = vector1->len - vector2->len;
 159        if (diff) {
 160                longer = (diff > 0) ? vector1->data : vector2->data;
 161
 162                /* Check to see if the longer number is
 163                 * lead-zero padded.  If it is not, it
 164                 * is automatically larger numerically.
 165                 */
 166                for (i = 0; i < abs(diff); i++) {
 167                        if (longer[i] != 0)
 168                                return diff;
 169                }
 170        }
 171
 172        /* lengths are the same, compare numbers */
 173        return memcmp(vector1->data, vector2->data, vector1->len);
 174}
 175
 176/*
 177 * Create a key vector as described in SCTP-AUTH, Section 6.1
 178 *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 179 *    parameter sent by each endpoint are concatenated as byte vectors.
 180 *    These parameters include the parameter type, parameter length, and
 181 *    the parameter value, but padding is omitted; all padding MUST be
 182 *    removed from this concatenation before proceeding with further
 183 *    computation of keys.  Parameters which were not sent are simply
 184 *    omitted from the concatenation process.  The resulting two vectors
 185 *    are called the two key vectors.
 186 */
 187static struct sctp_auth_bytes *sctp_auth_make_key_vector(
 188                        sctp_random_param_t *random,
 189                        sctp_chunks_param_t *chunks,
 190                        sctp_hmac_algo_param_t *hmacs,
 191                        gfp_t gfp)
 192{
 193        struct sctp_auth_bytes *new;
 194        __u32   len;
 195        __u32   offset = 0;
 196        __u16   random_len, hmacs_len, chunks_len = 0;
 197
 198        random_len = ntohs(random->param_hdr.length);
 199        hmacs_len = ntohs(hmacs->param_hdr.length);
 200        if (chunks)
 201                chunks_len = ntohs(chunks->param_hdr.length);
 202
 203        len = random_len + hmacs_len + chunks_len;
 204
 205        new = sctp_auth_create_key(len, gfp);
 206        if (!new)
 207                return NULL;
 208
 209        memcpy(new->data, random, random_len);
 210        offset += random_len;
 211
 212        if (chunks) {
 213                memcpy(new->data + offset, chunks, chunks_len);
 214                offset += chunks_len;
 215        }
 216
 217        memcpy(new->data + offset, hmacs, hmacs_len);
 218
 219        return new;
 220}
 221
 222
 223/* Make a key vector based on our local parameters */
 224static struct sctp_auth_bytes *sctp_auth_make_local_vector(
 225                                    const struct sctp_association *asoc,
 226                                    gfp_t gfp)
 227{
 228        return sctp_auth_make_key_vector(
 229                                    (sctp_random_param_t *)asoc->c.auth_random,
 230                                    (sctp_chunks_param_t *)asoc->c.auth_chunks,
 231                                    (sctp_hmac_algo_param_t *)asoc->c.auth_hmacs,
 232                                    gfp);
 233}
 234
 235/* Make a key vector based on peer's parameters */
 236static struct sctp_auth_bytes *sctp_auth_make_peer_vector(
 237                                    const struct sctp_association *asoc,
 238                                    gfp_t gfp)
 239{
 240        return sctp_auth_make_key_vector(asoc->peer.peer_random,
 241                                         asoc->peer.peer_chunks,
 242                                         asoc->peer.peer_hmacs,
 243                                         gfp);
 244}
 245
 246
 247/* Set the value of the association shared key base on the parameters
 248 * given.  The algorithm is:
 249 *    From the endpoint pair shared keys and the key vectors the
 250 *    association shared keys are computed.  This is performed by selecting
 251 *    the numerically smaller key vector and concatenating it to the
 252 *    endpoint pair shared key, and then concatenating the numerically
 253 *    larger key vector to that.  The result of the concatenation is the
 254 *    association shared key.
 255 */
 256static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
 257                        struct sctp_shared_key *ep_key,
 258                        struct sctp_auth_bytes *first_vector,
 259                        struct sctp_auth_bytes *last_vector,
 260                        gfp_t gfp)
 261{
 262        struct sctp_auth_bytes *secret;
 263        __u32 offset = 0;
 264        __u32 auth_len;
 265
 266        auth_len = first_vector->len + last_vector->len;
 267        if (ep_key->key)
 268                auth_len += ep_key->key->len;
 269
 270        secret = sctp_auth_create_key(auth_len, gfp);
 271        if (!secret)
 272                return NULL;
 273
 274        if (ep_key->key) {
 275                memcpy(secret->data, ep_key->key->data, ep_key->key->len);
 276                offset += ep_key->key->len;
 277        }
 278
 279        memcpy(secret->data + offset, first_vector->data, first_vector->len);
 280        offset += first_vector->len;
 281
 282        memcpy(secret->data + offset, last_vector->data, last_vector->len);
 283
 284        return secret;
 285}
 286
 287/* Create an association shared key.  Follow the algorithm
 288 * described in SCTP-AUTH, Section 6.1
 289 */
 290static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
 291                                 const struct sctp_association *asoc,
 292                                 struct sctp_shared_key *ep_key,
 293                                 gfp_t gfp)
 294{
 295        struct sctp_auth_bytes *local_key_vector;
 296        struct sctp_auth_bytes *peer_key_vector;
 297        struct sctp_auth_bytes  *first_vector,
 298                                *last_vector;
 299        struct sctp_auth_bytes  *secret = NULL;
 300        int     cmp;
 301
 302
 303        /* Now we need to build the key vectors
 304         * SCTP-AUTH , Section 6.1
 305         *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 306         *    parameter sent by each endpoint are concatenated as byte vectors.
 307         *    These parameters include the parameter type, parameter length, and
 308         *    the parameter value, but padding is omitted; all padding MUST be
 309         *    removed from this concatenation before proceeding with further
 310         *    computation of keys.  Parameters which were not sent are simply
 311         *    omitted from the concatenation process.  The resulting two vectors
 312         *    are called the two key vectors.
 313         */
 314
 315        local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
 316        peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
 317
 318        if (!peer_key_vector || !local_key_vector)
 319                goto out;
 320
 321        /* Figure out the order in which the key_vectors will be
 322         * added to the endpoint shared key.
 323         * SCTP-AUTH, Section 6.1:
 324         *   This is performed by selecting the numerically smaller key
 325         *   vector and concatenating it to the endpoint pair shared
 326         *   key, and then concatenating the numerically larger key
 327         *   vector to that.  If the key vectors are equal as numbers
 328         *   but differ in length, then the concatenation order is the
 329         *   endpoint shared key, followed by the shorter key vector,
 330         *   followed by the longer key vector.  Otherwise, the key
 331         *   vectors are identical, and may be concatenated to the
 332         *   endpoint pair key in any order.
 333         */
 334        cmp = sctp_auth_compare_vectors(local_key_vector,
 335                                        peer_key_vector);
 336        if (cmp < 0) {
 337                first_vector = local_key_vector;
 338                last_vector = peer_key_vector;
 339        } else {
 340                first_vector = peer_key_vector;
 341                last_vector = local_key_vector;
 342        }
 343
 344        secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
 345                                            gfp);
 346out:
 347        sctp_auth_key_put(local_key_vector);
 348        sctp_auth_key_put(peer_key_vector);
 349
 350        return secret;
 351}
 352
 353/*
 354 * Populate the association overlay list with the list
 355 * from the endpoint.
 356 */
 357int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
 358                                struct sctp_association *asoc,
 359                                gfp_t gfp)
 360{
 361        struct sctp_shared_key *sh_key;
 362        struct sctp_shared_key *new;
 363
 364        BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
 365
 366        key_for_each(sh_key, &ep->endpoint_shared_keys) {
 367                new = sctp_auth_shkey_create(sh_key->key_id, gfp);
 368                if (!new)
 369                        goto nomem;
 370
 371                new->key = sh_key->key;
 372                sctp_auth_key_hold(new->key);
 373                list_add(&new->key_list, &asoc->endpoint_shared_keys);
 374        }
 375
 376        return 0;
 377
 378nomem:
 379        sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
 380        return -ENOMEM;
 381}
 382
 383
 384/* Public interface to create the association shared key.
 385 * See code above for the algorithm.
 386 */
 387int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
 388{
 389        struct sctp_auth_bytes  *secret;
 390        struct sctp_shared_key *ep_key;
 391        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 */
 427struct 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 */
 449int 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
 496out_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 */
 503void 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
 518struct 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 */
 526struct 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
 569static 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 */
 585int 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 */
 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(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 */
 638static 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 */
 674int 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. */
 686int 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 */
 707void 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
 756free:
 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 */
 764int 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 */
 786int 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        memcpy(ep->auth_hmacs_list->hmac_ids, &hmacs->shmac_idents[0],
 813                hmacs->shmac_num_idents * sizeof(__u16));
 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 */
 823int 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;
 875nomem:
 876        if (!replace)
 877                sctp_auth_shkey_free(cur_key);
 878
 879        return -ENOMEM;
 880}
 881
 882int 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
 915int 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