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, write to
  20 * the Free Software Foundation, 59 Temple Place - Suite 330,
  21 * Boston, MA 02111-1307, USA.
  22 *
  23 * Please send any bug reports or fixes you make to the
  24 * email address(es):
  25 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  26 *
  27 * Or submit a bug report through the following website:
  28 *    http://www.sf.net/projects/lksctp
  29 *
  30 * Written or modified by:
  31 *   Vlad Yasevich     <vladislav.yasevich@hp.com>
  32 *
  33 * Any bugs reported given to us we will try to fix... any fixes shared will
  34 * be incorporated into the next SCTP release.
  35 */
  36
  37#include <linux/slab.h>
  38#include <linux/types.h>
  39#include <linux/crypto.h>
  40#include <linux/scatterlist.h>
  41#include <net/sctp/sctp.h>
  42#include <net/sctp/auth.h>
  43
  44static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
  45        {
  46                /* id 0 is reserved.  as all 0 */
  47                .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
  48        },
  49        {
  50                .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
  51                .hmac_name="hmac(sha1)",
  52                .hmac_len = SCTP_SHA1_SIG_SIZE,
  53        },
  54        {
  55                /* id 2 is reserved as well */
  56                .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
  57        },
  58#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
  59        {
  60                .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
  61                .hmac_name="hmac(sha256)",
  62                .hmac_len = SCTP_SHA256_SIG_SIZE,
  63        }
  64#endif
  65};
  66
  67
  68void sctp_auth_key_put(struct sctp_auth_bytes *key)
  69{
  70        if (!key)
  71                return;
  72
  73        if (atomic_dec_and_test(&key->refcnt)) {
  74                kfree(key);
  75                SCTP_DBG_OBJCNT_DEC(keys);
  76        }
  77}
  78
  79/* Create a new key structure of a given length */
  80static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
  81{
  82        struct sctp_auth_bytes *key;
  83
  84        /* Verify that we are not going to overflow INT_MAX */
  85        if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
  86                return NULL;
  87
  88        /* Allocate the shared key */
  89        key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
  90        if (!key)
  91                return NULL;
  92
  93        key->len = key_len;
  94        atomic_set(&key->refcnt, 1);
  95        SCTP_DBG_OBJCNT_INC(keys);
  96
  97        return key;
  98}
  99
 100/* Create a new shared key container with a give key id */
 101struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
 102{
 103        struct sctp_shared_key *new;
 104
 105        /* Allocate the shared key container */
 106        new = kzalloc(sizeof(struct sctp_shared_key), gfp);
 107        if (!new)
 108                return NULL;
 109
 110        INIT_LIST_HEAD(&new->key_list);
 111        new->key_id = key_id;
 112
 113        return new;
 114}
 115
 116/* Free the shared key structure */
 117static void sctp_auth_shkey_free(struct sctp_shared_key *sh_key)
 118{
 119        BUG_ON(!list_empty(&sh_key->key_list));
 120        sctp_auth_key_put(sh_key->key);
 121        sh_key->key = NULL;
 122        kfree(sh_key);
 123}
 124
 125/* Destroy the entire key list.  This is done during the
 126 * associon and endpoint free process.
 127 */
 128void sctp_auth_destroy_keys(struct list_head *keys)
 129{
 130        struct sctp_shared_key *ep_key;
 131        struct sctp_shared_key *tmp;
 132
 133        if (list_empty(keys))
 134                return;
 135
 136        key_for_each_safe(ep_key, tmp, keys) {
 137                list_del_init(&ep_key->key_list);
 138                sctp_auth_shkey_free(ep_key);
 139        }
 140}
 141
 142/* Compare two byte vectors as numbers.  Return values
 143 * are:
 144 *        0 - vectors are equal
 145 *      < 0 - vector 1 is smaller than vector2
 146 *      > 0 - vector 1 is greater than vector2
 147 *
 148 * Algorithm is:
 149 *      This is performed by selecting the numerically smaller key vector...
 150 *      If the key vectors are equal as numbers but differ in length ...
 151 *      the shorter vector is considered smaller
 152 *
 153 * Examples (with small values):
 154 *      000123456789 > 123456789 (first number is longer)
 155 *      000123456789 < 234567891 (second number is larger numerically)
 156 *      123456789 > 2345678      (first number is both larger & longer)
 157 */
 158static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
 159                              struct sctp_auth_bytes *vector2)
 160{
 161        int diff;
 162        int i;
 163        const __u8 *longer;
 164
 165        diff = vector1->len - vector2->len;
 166        if (diff) {
 167                longer = (diff > 0) ? vector1->data : vector2->data;
 168
 169                /* Check to see if the longer number is
 170                 * lead-zero padded.  If it is not, it
 171                 * is automatically larger numerically.
 172                 */
 173                for (i = 0; i < abs(diff); i++ ) {
 174                        if (longer[i] != 0)
 175                                return diff;
 176                }
 177        }
 178
 179        /* lengths are the same, compare numbers */
 180        return memcmp(vector1->data, vector2->data, vector1->len);
 181}
 182
 183/*
 184 * Create a key vector as described in SCTP-AUTH, Section 6.1
 185 *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 186 *    parameter sent by each endpoint are concatenated as byte vectors.
 187 *    These parameters include the parameter type, parameter length, and
 188 *    the parameter value, but padding is omitted; all padding MUST be
 189 *    removed from this concatenation before proceeding with further
 190 *    computation of keys.  Parameters which were not sent are simply
 191 *    omitted from the concatenation process.  The resulting two vectors
 192 *    are called the two key vectors.
 193 */
 194static struct sctp_auth_bytes *sctp_auth_make_key_vector(
 195                        sctp_random_param_t *random,
 196                        sctp_chunks_param_t *chunks,
 197                        sctp_hmac_algo_param_t *hmacs,
 198                        gfp_t gfp)
 199{
 200        struct sctp_auth_bytes *new;
 201        __u32   len;
 202        __u32   offset = 0;
 203
 204        len = ntohs(random->param_hdr.length) + ntohs(hmacs->param_hdr.length);
 205        if (chunks)
 206                len += ntohs(chunks->param_hdr.length);
 207
 208        new = kmalloc(sizeof(struct sctp_auth_bytes) + len, gfp);
 209        if (!new)
 210                return NULL;
 211
 212        new->len = len;
 213
 214        memcpy(new->data, random, ntohs(random->param_hdr.length));
 215        offset += ntohs(random->param_hdr.length);
 216
 217        if (chunks) {
 218                memcpy(new->data + offset, chunks,
 219                        ntohs(chunks->param_hdr.length));
 220                offset += ntohs(chunks->param_hdr.length);
 221        }
 222
 223        memcpy(new->data + offset, hmacs, ntohs(hmacs->param_hdr.length));
 224
 225        return new;
 226}
 227
 228
 229/* Make a key vector based on our local parameters */
 230static struct sctp_auth_bytes *sctp_auth_make_local_vector(
 231                                    const struct sctp_association *asoc,
 232                                    gfp_t gfp)
 233{
 234        return sctp_auth_make_key_vector(
 235                                    (sctp_random_param_t*)asoc->c.auth_random,
 236                                    (sctp_chunks_param_t*)asoc->c.auth_chunks,
 237                                    (sctp_hmac_algo_param_t*)asoc->c.auth_hmacs,
 238                                    gfp);
 239}
 240
 241/* Make a key vector based on peer's parameters */
 242static struct sctp_auth_bytes *sctp_auth_make_peer_vector(
 243                                    const struct sctp_association *asoc,
 244                                    gfp_t gfp)
 245{
 246        return sctp_auth_make_key_vector(asoc->peer.peer_random,
 247                                         asoc->peer.peer_chunks,
 248                                         asoc->peer.peer_hmacs,
 249                                         gfp);
 250}
 251
 252
 253/* Set the value of the association shared key base on the parameters
 254 * given.  The algorithm is:
 255 *    From the endpoint pair shared keys and the key vectors the
 256 *    association shared keys are computed.  This is performed by selecting
 257 *    the numerically smaller key vector and concatenating it to the
 258 *    endpoint pair shared key, and then concatenating the numerically
 259 *    larger key vector to that.  The result of the concatenation is the
 260 *    association shared key.
 261 */
 262static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
 263                        struct sctp_shared_key *ep_key,
 264                        struct sctp_auth_bytes *first_vector,
 265                        struct sctp_auth_bytes *last_vector,
 266                        gfp_t gfp)
 267{
 268        struct sctp_auth_bytes *secret;
 269        __u32 offset = 0;
 270        __u32 auth_len;
 271
 272        auth_len = first_vector->len + last_vector->len;
 273        if (ep_key->key)
 274                auth_len += ep_key->key->len;
 275
 276        secret = sctp_auth_create_key(auth_len, gfp);
 277        if (!secret)
 278                return NULL;
 279
 280        if (ep_key->key) {
 281                memcpy(secret->data, ep_key->key->data, ep_key->key->len);
 282                offset += ep_key->key->len;
 283        }
 284
 285        memcpy(secret->data + offset, first_vector->data, first_vector->len);
 286        offset += first_vector->len;
 287
 288        memcpy(secret->data + offset, last_vector->data, last_vector->len);
 289
 290        return secret;
 291}
 292
 293/* Create an association shared key.  Follow the algorithm
 294 * described in SCTP-AUTH, Section 6.1
 295 */
 296static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
 297                                 const struct sctp_association *asoc,
 298                                 struct sctp_shared_key *ep_key,
 299                                 gfp_t gfp)
 300{
 301        struct sctp_auth_bytes *local_key_vector;
 302        struct sctp_auth_bytes *peer_key_vector;
 303        struct sctp_auth_bytes  *first_vector,
 304                                *last_vector;
 305        struct sctp_auth_bytes  *secret = NULL;
 306        int     cmp;
 307
 308
 309        /* Now we need to build the key vectors
 310         * SCTP-AUTH , Section 6.1
 311         *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 312         *    parameter sent by each endpoint are concatenated as byte vectors.
 313         *    These parameters include the parameter type, parameter length, and
 314         *    the parameter value, but padding is omitted; all padding MUST be
 315         *    removed from this concatenation before proceeding with further
 316         *    computation of keys.  Parameters which were not sent are simply
 317         *    omitted from the concatenation process.  The resulting two vectors
 318         *    are called the two key vectors.
 319         */
 320
 321        local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
 322        peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
 323
 324        if (!peer_key_vector || !local_key_vector)
 325                goto out;
 326
 327        /* Figure out the order in which the key_vectors will be
 328         * added to the endpoint shared key.
 329         * SCTP-AUTH, Section 6.1:
 330         *   This is performed by selecting the numerically smaller key
 331         *   vector and concatenating it to the endpoint pair shared
 332         *   key, and then concatenating the numerically larger key
 333         *   vector to that.  If the key vectors are equal as numbers
 334         *   but differ in length, then the concatenation order is the
 335         *   endpoint shared key, followed by the shorter key vector,
 336         *   followed by the longer key vector.  Otherwise, the key
 337         *   vectors are identical, and may be concatenated to the
 338         *   endpoint pair key in any order.
 339         */
 340        cmp = sctp_auth_compare_vectors(local_key_vector,
 341                                        peer_key_vector);
 342        if (cmp < 0) {
 343                first_vector = local_key_vector;
 344                last_vector = peer_key_vector;
 345        } else {
 346                first_vector = peer_key_vector;
 347                last_vector = local_key_vector;
 348        }
 349
 350        secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
 351                                            gfp);
 352out:
 353        kfree(local_key_vector);
 354        kfree(peer_key_vector);
 355
 356        return secret;
 357}
 358
 359/*
 360 * Populate the association overlay list with the list
 361 * from the endpoint.
 362 */
 363int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
 364                                struct sctp_association *asoc,
 365                                gfp_t gfp)
 366{
 367        struct sctp_shared_key *sh_key;
 368        struct sctp_shared_key *new;
 369
 370        BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
 371
 372        key_for_each(sh_key, &ep->endpoint_shared_keys) {
 373                new = sctp_auth_shkey_create(sh_key->key_id, gfp);
 374                if (!new)
 375                        goto nomem;
 376
 377                new->key = sh_key->key;
 378                sctp_auth_key_hold(new->key);
 379                list_add(&new->key_list, &asoc->endpoint_shared_keys);
 380        }
 381
 382        return 0;
 383
 384nomem:
 385        sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
 386        return -ENOMEM;
 387}
 388
 389
 390/* Public interface to creat the association shared key.
 391 * See code above for the algorithm.
 392 */
 393int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
 394{
 395        struct sctp_auth_bytes  *secret;
 396        struct sctp_shared_key *ep_key;
 397
 398        /* If we don't support AUTH, or peer is not capable
 399         * we don't need to do anything.
 400         */
 401        if (!sctp_auth_enable || !asoc->peer.auth_capable)
 402                return 0;
 403
 404        /* If the key_id is non-zero and we couldn't find an
 405         * endpoint pair shared key, we can't compute the
 406         * secret.
 407         * For key_id 0, endpoint pair shared key is a NULL key.
 408         */
 409        ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
 410        BUG_ON(!ep_key);
 411
 412        secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
 413        if (!secret)
 414                return -ENOMEM;
 415
 416        sctp_auth_key_put(asoc->asoc_shared_key);
 417        asoc->asoc_shared_key = secret;
 418
 419        return 0;
 420}
 421
 422
 423/* Find the endpoint pair shared key based on the key_id */
 424struct sctp_shared_key *sctp_auth_get_shkey(
 425                                const struct sctp_association *asoc,
 426                                __u16 key_id)
 427{
 428        struct sctp_shared_key *key;
 429
 430        /* First search associations set of endpoint pair shared keys */
 431        key_for_each(key, &asoc->endpoint_shared_keys) {
 432                if (key->key_id == key_id)
 433                        return key;
 434        }
 435
 436        return NULL;
 437}
 438
 439/*
 440 * Initialize all the possible digest transforms that we can use.  Right now
 441 * now, the supported digests are SHA1 and SHA256.  We do this here once
 442 * because of the restrictiong that transforms may only be allocated in
 443 * user context.  This forces us to pre-allocated all possible transforms
 444 * at the endpoint init time.
 445 */
 446int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
 447{
 448        struct crypto_hash *tfm = NULL;
 449        __u16   id;
 450
 451        /* if the transforms are already allocted, we are done */
 452        if (!sctp_auth_enable) {
 453                ep->auth_hmacs = NULL;
 454                return 0;
 455        }
 456
 457        if (ep->auth_hmacs)
 458                return 0;
 459
 460        /* Allocated the array of pointers to transorms */
 461        ep->auth_hmacs = kzalloc(
 462                            sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
 463                            gfp);
 464        if (!ep->auth_hmacs)
 465                return -ENOMEM;
 466
 467        for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
 468
 469                /* See is we support the id.  Supported IDs have name and
 470                 * length fields set, so that we can allocated and use
 471                 * them.  We can safely just check for name, for without the
 472                 * name, we can't allocate the TFM.
 473                 */
 474                if (!sctp_hmac_list[id].hmac_name)
 475                        continue;
 476
 477                /* If this TFM has been allocated, we are all set */
 478                if (ep->auth_hmacs[id])
 479                        continue;
 480
 481                /* Allocate the ID */
 482                tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
 483                                        CRYPTO_ALG_ASYNC);
 484                if (IS_ERR(tfm))
 485                        goto out_err;
 486
 487                ep->auth_hmacs[id] = tfm;
 488        }
 489
 490        return 0;
 491
 492out_err:
 493        /* Clean up any successful allocations */
 494        sctp_auth_destroy_hmacs(ep->auth_hmacs);
 495        return -ENOMEM;
 496}
 497
 498/* Destroy the hmac tfm array */
 499void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
 500{
 501        int i;
 502
 503        if (!auth_hmacs)
 504                return;
 505
 506        for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++)
 507        {
 508                if (auth_hmacs[i])
 509                        crypto_free_hash(auth_hmacs[i]);
 510        }
 511        kfree(auth_hmacs);
 512}
 513
 514
 515struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
 516{
 517        return &sctp_hmac_list[hmac_id];
 518}
 519
 520/* Get an hmac description information that we can use to build
 521 * the AUTH chunk
 522 */
 523struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
 524{
 525        struct sctp_hmac_algo_param *hmacs;
 526        __u16 n_elt;
 527        __u16 id = 0;
 528        int i;
 529
 530        /* If we have a default entry, use it */
 531        if (asoc->default_hmac_id)
 532                return &sctp_hmac_list[asoc->default_hmac_id];
 533
 534        /* Since we do not have a default entry, find the first entry
 535         * we support and return that.  Do not cache that id.
 536         */
 537        hmacs = asoc->peer.peer_hmacs;
 538        if (!hmacs)
 539                return NULL;
 540
 541        n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
 542        for (i = 0; i < n_elt; i++) {
 543                id = ntohs(hmacs->hmac_ids[i]);
 544
 545                /* Check the id is in the supported range */
 546                if (id > SCTP_AUTH_HMAC_ID_MAX) {
 547                        id = 0;
 548                        continue;
 549                }
 550
 551                /* See is we support the id.  Supported IDs have name and
 552                 * length fields set, so that we can allocated and use
 553                 * them.  We can safely just check for name, for without the
 554                 * name, we can't allocate the TFM.
 555                 */
 556                if (!sctp_hmac_list[id].hmac_name) {
 557                        id = 0;
 558                        continue;
 559                }
 560
 561                break;
 562        }
 563
 564        if (id == 0)
 565                return NULL;
 566
 567        return &sctp_hmac_list[id];
 568}
 569
 570static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
 571{
 572        int  found = 0;
 573        int  i;
 574
 575        for (i = 0; i < n_elts; i++) {
 576                if (hmac_id == hmacs[i]) {
 577                        found = 1;
 578                        break;
 579                }
 580        }
 581
 582        return found;
 583}
 584
 585/* See if the HMAC_ID is one that we claim as supported */
 586int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
 587                                    __be16 hmac_id)
 588{
 589        struct sctp_hmac_algo_param *hmacs;
 590        __u16 n_elt;
 591
 592        if (!asoc)
 593                return 0;
 594
 595        hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
 596        n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
 597
 598        return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
 599}
 600
 601
 602/* Cache the default HMAC id.  This to follow this text from SCTP-AUTH:
 603 * Section 6.1:
 604 *   The receiver of a HMAC-ALGO parameter SHOULD use the first listed
 605 *   algorithm it supports.
 606 */
 607void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
 608                                     struct sctp_hmac_algo_param *hmacs)
 609{
 610        struct sctp_endpoint *ep;
 611        __u16   id;
 612        int     i;
 613        int     n_params;
 614
 615        /* if the default id is already set, use it */
 616        if (asoc->default_hmac_id)
 617                return;
 618
 619        n_params = (ntohs(hmacs->param_hdr.length)
 620                                - sizeof(sctp_paramhdr_t)) >> 1;
 621        ep = asoc->ep;
 622        for (i = 0; i < n_params; i++) {
 623                id = ntohs(hmacs->hmac_ids[i]);
 624
 625                /* Check the id is in the supported range */
 626                if (id > SCTP_AUTH_HMAC_ID_MAX)
 627                        continue;
 628
 629                /* If this TFM has been allocated, use this id */
 630                if (ep->auth_hmacs[id]) {
 631                        asoc->default_hmac_id = id;
 632                        break;
 633                }
 634        }
 635}
 636
 637
 638/* Check to see if the given chunk is supposed to be authenticated */
 639static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
 640{
 641        unsigned short len;
 642        int found = 0;
 643        int i;
 644
 645        if (!param || param->param_hdr.length == 0)
 646                return 0;
 647
 648        len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);
 649
 650        /* SCTP-AUTH, Section 3.2
 651         *    The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
 652         *    chunks MUST NOT be listed in the CHUNKS parameter.  However, if
 653         *    a CHUNKS parameter is received then the types for INIT, INIT-ACK,
 654         *    SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
 655         */
 656        for (i = 0; !found && i < len; i++) {
 657                switch (param->chunks[i]) {
 658                    case SCTP_CID_INIT:
 659                    case SCTP_CID_INIT_ACK:
 660                    case SCTP_CID_SHUTDOWN_COMPLETE:
 661                    case SCTP_CID_AUTH:
 662                        break;
 663
 664                    default:
 665                        if (param->chunks[i] == chunk)
 666                            found = 1;
 667                        break;
 668                }
 669        }
 670
 671        return found;
 672}
 673
 674/* Check if peer requested that this chunk is authenticated */
 675int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
 676{
 677        if (!sctp_auth_enable || !asoc || !asoc->peer.auth_capable)
 678                return 0;
 679
 680        return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
 681}
 682
 683/* Check if we requested that peer authenticate this chunk. */
 684int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
 685{
 686        if (!sctp_auth_enable || !asoc)
 687                return 0;
 688
 689        return __sctp_auth_cid(chunk,
 690                              (struct sctp_chunks_param *)asoc->c.auth_chunks);
 691}
 692
 693/* SCTP-AUTH: Section 6.2:
 694 *    The sender MUST calculate the MAC as described in RFC2104 [2] using
 695 *    the hash function H as described by the MAC Identifier and the shared
 696 *    association key K based on the endpoint pair shared key described by
 697 *    the shared key identifier.  The 'data' used for the computation of
 698 *    the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
 699 *    zero (as shown in Figure 6) followed by all chunks that are placed
 700 *    after the AUTH chunk in the SCTP packet.
 701 */
 702void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
 703                              struct sk_buff *skb,
 704                              struct sctp_auth_chunk *auth,
 705                              gfp_t gfp)
 706{
 707        struct scatterlist sg;
 708        struct hash_desc desc;
 709        struct sctp_auth_bytes *asoc_key;
 710        __u16 key_id, hmac_id;
 711        __u8 *digest;
 712        unsigned char *end;
 713        int free_key = 0;
 714
 715        /* Extract the info we need:
 716         * - hmac id
 717         * - key id
 718         */
 719        key_id = ntohs(auth->auth_hdr.shkey_id);
 720        hmac_id = ntohs(auth->auth_hdr.hmac_id);
 721
 722        if (key_id == asoc->active_key_id)
 723                asoc_key = asoc->asoc_shared_key;
 724        else {
 725                struct sctp_shared_key *ep_key;
 726
 727                ep_key = sctp_auth_get_shkey(asoc, key_id);
 728                if (!ep_key)
 729                        return;
 730
 731                asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
 732                if (!asoc_key)
 733                        return;
 734
 735                free_key = 1;
 736        }
 737
 738        /* set up scatter list */
 739        end = skb_tail_pointer(skb);
 740        sg_init_one(&sg, auth, end - (unsigned char *)auth);
 741
 742        desc.tfm = asoc->ep->auth_hmacs[hmac_id];
 743        desc.flags = 0;
 744
 745        digest = auth->auth_hdr.hmac;
 746        if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
 747                goto free;
 748
 749        crypto_hash_digest(&desc, &sg, sg.length, digest);
 750
 751free:
 752        if (free_key)
 753                sctp_auth_key_put(asoc_key);
 754}
 755
 756/* API Helpers */
 757
 758/* Add a chunk to the endpoint authenticated chunk list */
 759int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
 760{
 761        struct sctp_chunks_param *p = ep->auth_chunk_list;
 762        __u16 nchunks;
 763        __u16 param_len;
 764
 765        /* If this chunk is already specified, we are done */
 766        if (__sctp_auth_cid(chunk_id, p))
 767                return 0;
 768
 769        /* Check if we can add this chunk to the array */
 770        param_len = ntohs(p->param_hdr.length);
 771        nchunks = param_len - sizeof(sctp_paramhdr_t);
 772        if (nchunks == SCTP_NUM_CHUNK_TYPES)
 773                return -EINVAL;
 774
 775        p->chunks[nchunks] = chunk_id;
 776        p->param_hdr.length = htons(param_len + 1);
 777        return 0;
 778}
 779
 780/* Add hmac identifires to the endpoint list of supported hmac ids */
 781int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
 782                           struct sctp_hmacalgo *hmacs)
 783{
 784        int has_sha1 = 0;
 785        __u16 id;
 786        int i;
 787
 788        /* Scan the list looking for unsupported id.  Also make sure that
 789         * SHA1 is specified.
 790         */
 791        for (i = 0; i < hmacs->shmac_num_idents; i++) {
 792                id = hmacs->shmac_idents[i];
 793
 794                if (id > SCTP_AUTH_HMAC_ID_MAX)
 795                        return -EOPNOTSUPP;
 796
 797                if (SCTP_AUTH_HMAC_ID_SHA1 == id)
 798                        has_sha1 = 1;
 799
 800                if (!sctp_hmac_list[id].hmac_name)
 801                        return -EOPNOTSUPP;
 802        }
 803
 804        if (!has_sha1)
 805                return -EINVAL;
 806
 807        memcpy(ep->auth_hmacs_list->hmac_ids, &hmacs->shmac_idents[0],
 808                hmacs->shmac_num_idents * sizeof(__u16));
 809        ep->auth_hmacs_list->param_hdr.length = htons(sizeof(sctp_paramhdr_t) +
 810                                hmacs->shmac_num_idents * sizeof(__u16));
 811        return 0;
 812}
 813
 814/* Set a new shared key on either endpoint or association.  If the
 815 * the key with a same ID already exists, replace the key (remove the
 816 * old key and add a new one).
 817 */
 818int sctp_auth_set_key(struct sctp_endpoint *ep,
 819                      struct sctp_association *asoc,
 820                      struct sctp_authkey *auth_key)
 821{
 822        struct sctp_shared_key *cur_key = NULL;
 823        struct sctp_auth_bytes *key;
 824        struct list_head *sh_keys;
 825        int replace = 0;
 826
 827        /* Try to find the given key id to see if
 828         * we are doing a replace, or adding a new key
 829         */
 830        if (asoc)
 831                sh_keys = &asoc->endpoint_shared_keys;
 832        else
 833                sh_keys = &ep->endpoint_shared_keys;
 834
 835        key_for_each(cur_key, sh_keys) {
 836                if (cur_key->key_id == auth_key->sca_keynumber) {
 837                        replace = 1;
 838                        break;
 839                }
 840        }
 841
 842        /* If we are not replacing a key id, we need to allocate
 843         * a shared key.
 844         */
 845        if (!replace) {
 846                cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber,
 847                                                 GFP_KERNEL);
 848                if (!cur_key)
 849                        return -ENOMEM;
 850        }
 851
 852        /* Create a new key data based on the info passed in */
 853        key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
 854        if (!key)
 855                goto nomem;
 856
 857        memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);
 858
 859        /* If we are replacing, remove the old keys data from the
 860         * key id.  If we are adding new key id, add it to the
 861         * list.
 862         */
 863        if (replace)
 864                sctp_auth_key_put(cur_key->key);
 865        else
 866                list_add(&cur_key->key_list, sh_keys);
 867
 868        cur_key->key = key;
 869        sctp_auth_key_hold(key);
 870
 871        return 0;
 872nomem:
 873        if (!replace)
 874                sctp_auth_shkey_free(cur_key);
 875
 876        return -ENOMEM;
 877}
 878
 879int sctp_auth_set_active_key(struct sctp_endpoint *ep,
 880                             struct sctp_association *asoc,
 881                             __u16  key_id)
 882{
 883        struct sctp_shared_key *key;
 884        struct list_head *sh_keys;
 885        int found = 0;
 886
 887        /* The key identifier MUST correst to an existing key */
 888        if (asoc)
 889                sh_keys = &asoc->endpoint_shared_keys;
 890        else
 891                sh_keys = &ep->endpoint_shared_keys;
 892
 893        key_for_each(key, sh_keys) {
 894                if (key->key_id == key_id) {
 895                        found = 1;
 896                        break;
 897                }
 898        }
 899
 900        if (!found)
 901                return -EINVAL;
 902
 903        if (asoc) {
 904                asoc->active_key_id = key_id;
 905                sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL);
 906        } else
 907                ep->active_key_id = key_id;
 908
 909        return 0;
 910}
 911
 912int sctp_auth_del_key_id(struct sctp_endpoint *ep,
 913                         struct sctp_association *asoc,
 914                         __u16  key_id)
 915{
 916        struct sctp_shared_key *key;
 917        struct list_head *sh_keys;
 918        int found = 0;
 919
 920        /* The key identifier MUST NOT be the current active key
 921         * The key identifier MUST correst to an existing key
 922         */
 923        if (asoc) {
 924                if (asoc->active_key_id == key_id)
 925                        return -EINVAL;
 926
 927                sh_keys = &asoc->endpoint_shared_keys;
 928        } else {
 929                if (ep->active_key_id == key_id)
 930                        return -EINVAL;
 931
 932                sh_keys = &ep->endpoint_shared_keys;
 933        }
 934
 935        key_for_each(key, sh_keys) {
 936                if (key->key_id == key_id) {
 937                        found = 1;
 938                        break;
 939                }
 940        }
 941
 942        if (!found)
 943                return -EINVAL;
 944
 945        /* Delete the shared key */
 946        list_del_init(&key->key_list);
 947        sctp_auth_shkey_free(key);
 948
 949        return 0;
 950}
 951
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