src/eap_server/eap_server_pwd.c

   1 /*
   2  * hostapd / EAP-pwd (RFC 5931) server
   3  * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the BSD license.
   7  *
   8  * Alternatively, this software may be distributed under the terms of the
   9  * GNU General Public License version 2 as published by the Free Software
  10  * Foundation.
  11  *
  12  * See README and COPYING for more details.
  13  */
  14
  15 #include "includes.h"
  16
  17 #include "common.h"
  18 #include "eap_server/eap_i.h"
  19 #include "eap_common/eap_pwd_common.h"
  20
  21
  22 struct eap_pwd_data {
  23         enum {
  24                 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
  25         } state;
  26         u8 *id_peer;
  27         size_t id_peer_len;
  28         u8 *id_server;
  29         size_t id_server_len;
  30         u8 *password;
  31         size_t password_len;
  32         u32 token;
  33         u16 group_num;
  34         EAP_PWD_group *grp;
  35
  36         BIGNUM *k;
  37         BIGNUM *private_value;
  38         BIGNUM *peer_scalar;
  39         BIGNUM *my_scalar;
  40         EC_POINT *my_element;
  41         EC_POINT *peer_element;
  42
  43         u8 msk[EAP_MSK_LEN];
  44         u8 emsk[EAP_EMSK_LEN];
  45 };
  46
  47 static BN_CTX *bnctx;
  48
  49
  50 static const char * eap_pwd_state_txt(int state)
  51 {
  52         switch (state) {
  53         case PWD_ID_Req:
  54                 return "PWD-ID-Req";
  55         case PWD_Commit_Req:
  56                 return "PWD-Commit-Req";
  57         case PWD_Confirm_Req:
  58                 return "PWD-Confirm-Req";
  59         case SUCCESS:
  60                 return "SUCCESS";
  61         case FAILURE:
  62                 return "FAILURE";
  63         default:
  64                 return "PWD-Unk";
  65         }
  66 }
  67
  68
  69 static void eap_pwd_state(struct eap_pwd_data *data, int state)
  70 {
  71         wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
  72                    eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
  73         data->state = state;
  74 }
  75
  76
  77 static void * eap_pwd_init(struct eap_sm *sm)
  78 {
  79         struct eap_pwd_data *data;
  80
  81         if (sm->user == NULL || sm->user->password == NULL ||
  82             sm->user->password_len == 0) {
  83                 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
  84                            "configured");
  85                 return NULL;
  86         }
  87
  88         data = os_zalloc(sizeof(*data));
  89         if (data == NULL)
  90                 return NULL;
  91
  92         data->group_num = sm->pwd_group;
  93         wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
  94                    data->group_num);
  95         data->state = PWD_ID_Req;
  96
  97         data->id_server = (u8 *) os_strdup("server");
  98         if (data->id_server)
  99                 data->id_server_len = os_strlen((char *)data->id_server);
 100
 101         data->password = os_malloc(sm->user->password_len);
 102         if (data->password == NULL) {
 103                 wpa_printf(MSG_INFO, "EAP-PWD: Mmemory allocation password "
 104                            "fail");
 105                 return NULL;
 106         }
 107         data->password_len = sm->user->password_len;
 108         os_memcpy(data->password, sm->user->password, data->password_len);
 109
 110         bnctx = BN_CTX_new();
 111         if (bnctx == NULL) {
 112                 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
 113                 return NULL;
 114         }
 115
 116         return data;
 117 }
 118
 119
 120 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
 121 {
 122         struct eap_pwd_data *data = priv;
 123
 124         BN_free(data->private_value);
 125         BN_free(data->peer_scalar);
 126         BN_free(data->my_scalar);
 127         BN_free(data->k);
 128         BN_CTX_free(bnctx);
 129         EC_POINT_free(data->my_element);
 130         EC_POINT_free(data->peer_element);
 131         os_free(data->id_peer);
 132         os_free(data->id_server);
 133         os_free(data->grp);
 134         os_free(data);
 135 }
 136
 137
 138 static struct wpabuf *
 139 eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
 140 {
 141         struct wpabuf *req;
 142
 143         wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
 144         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 145                             sizeof(struct eap_pwd_hdr) +
 146                             sizeof(struct eap_pwd_id) + data->id_server_len,
 147                             EAP_CODE_REQUEST, id);
 148         if (req == NULL) {
 149                 eap_pwd_state(data, FAILURE);
 150                 return NULL;
 151         }
 152
 153         /* an lfsr is good enough to generate unpredictable tokens */
 154         data->token = os_random();
 155         wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
 156         wpabuf_put_be16(req, data->group_num);
 157         wpabuf_put_u8(req, EAP_PWD_DEFAULT_RAND_FUNC);
 158         wpabuf_put_u8(req, EAP_PWD_DEFAULT_PRF);
 159         wpabuf_put_data(req, &data->token, sizeof(data->token));
 160         wpabuf_put_u8(req, EAP_PWD_PREP_NONE);
 161         wpabuf_put_data(req, data->id_server, data->id_server_len);
 162
 163         return req;
 164 }
 165
 166
 167 static struct wpabuf *
 168 eap_pwd_build_commit_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
 169 {
 170         struct wpabuf *req = NULL;
 171         BIGNUM *mask = NULL, *x = NULL, *y = NULL;
 172         u8 *scalar = NULL, *element = NULL;
 173         u16 offset;
 174
 175         wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
 176
 177         if (((data->private_value = BN_new()) == NULL) ||
 178             ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
 179             ((data->my_scalar = BN_new()) == NULL) ||
 180             ((mask = BN_new()) == NULL)) {
 181                 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
 182                            "fail");
 183                 goto fin;
 184         }
 185
 186         BN_rand_range(data->private_value, data->grp->order);
 187         BN_rand_range(mask, data->grp->order);
 188         BN_add(data->my_scalar, data->private_value, mask);
 189         BN_mod(data->my_scalar, data->my_scalar, data->grp->order, bnctx);
 190
 191         if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
 192                           data->grp->pwe, mask, bnctx)) {
 193                 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
 194                            "fail");
 195                 eap_pwd_state(data, FAILURE);
 196                 goto fin;
 197         }
 198
 199         if (!EC_POINT_invert(data->grp->group, data->my_element, bnctx)) {
 200                 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
 201                            "fail");
 202                 goto fin;
 203         }
 204         BN_free(mask);
 205
 206         if (((x = BN_new()) == NULL) ||
 207             ((y = BN_new()) == NULL)) {
 208                 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
 209                            "fail");
 210                 goto fin;
 211         }
 212         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 213                                                  data->my_element, x, y,
 214                                                  bnctx)) {
 215                 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
 216                            "fail");
 217                 goto fin;
 218         }
 219
 220         if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
 221             ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
 222              NULL)) {
 223                 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
 224                 goto fin;
 225         }
 226
 227         /*
 228          * bignums occupy as little memory as possible so one that is
 229          * sufficiently smaller than the prime or order might need pre-pending
 230          * with zeros.
 231          */
 232         os_memset(scalar, 0, BN_num_bytes(data->grp->order));
 233         os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
 234         offset = BN_num_bytes(data->grp->order) -
 235                 BN_num_bytes(data->my_scalar);
 236         BN_bn2bin(data->my_scalar, scalar + offset);
 237
 238         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 239         BN_bn2bin(x, element + offset);
 240         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 241         BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
 242
 243         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 244                             sizeof(struct eap_pwd_hdr) +
 245                             (2 * BN_num_bytes(data->grp->prime)) +
 246                             BN_num_bytes(data->grp->order),
 247                             EAP_CODE_REQUEST, id);
 248         if (req == NULL)
 249                 goto fin;
 250         wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
 251
 252         /* We send the element as (x,y) followed by the scalar */
 253         wpabuf_put_data(req, element, (2 * BN_num_bytes(data->grp->prime)));
 254         wpabuf_put_data(req, scalar, BN_num_bytes(data->grp->order));
 255
 256 fin:
 257         os_free(scalar);
 258         os_free(element);
 259         BN_free(x);
 260         BN_free(y);
 261         if (req == NULL)
 262                 eap_pwd_state(data, FAILURE);
 263
 264         return req;
 265 }
 266
 267
 268 static struct wpabuf *
 269 eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
 270 {
 271         struct wpabuf *req = NULL;
 272         BIGNUM *x = NULL, *y = NULL;
 273         HMAC_CTX ctx;
 274         u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;
 275
 276         wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
 277
 278         /* Each component of the cruft will be at most as big as the prime */
 279         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 280             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 281                 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
 282                            "fail");
 283                 goto fin;
 284         }
 285
 286         /*
 287          * commit is H(k | server_element | server_scalar | peer_element |
 288          *             peer_scalar | ciphersuite)
 289          */
 290         H_Init(&ctx);
 291
 292         /*
 293          * Zero the memory each time because this is mod prime math and some
 294          * value may start with a few zeros and the previous one did not.
 295          *
 296          * First is k
 297          */
 298         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 299         BN_bn2bin(data->k, cruft);
 300         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 301
 302         /* server element: x, y */
 303         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 304                                                  data->my_element, x, y,
 305                                                  bnctx)) {
 306                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 307                            "assignment fail");
 308                 goto fin;
 309         }
 310
 311         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 312         BN_bn2bin(x, cruft);
 313         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 314         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 315         BN_bn2bin(y, cruft);
 316         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 317
 318         /* server scalar */
 319         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 320         BN_bn2bin(data->my_scalar, cruft);
 321         H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
 322
 323         /* peer element: x, y */
 324         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 325                                                  data->peer_element, x, y,
 326                                                  bnctx)) {
 327                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 328                            "assignment fail");
 329                 goto fin;
 330         }
 331
 332         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 333         BN_bn2bin(x, cruft);
 334         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 335         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 336         BN_bn2bin(y, cruft);
 337         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 338
 339         /* peer scalar */
 340         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 341         BN_bn2bin(data->peer_scalar, cruft);
 342         H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
 343
 344         /* ciphersuite */
 345         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 346         ptr = cruft;
 347         os_memcpy(ptr, &data->group_num, sizeof(u16));
 348         ptr += sizeof(u16);
 349         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 350         ptr += sizeof(u8);
 351         *ptr = EAP_PWD_DEFAULT_PRF;
 352         ptr += sizeof(u8);
 353         H_Update(&ctx, cruft, ptr-cruft);
 354
 355         /* all done with the random function */
 356         H_Final(&ctx, conf);
 357
 358         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 359                             sizeof(struct eap_pwd_hdr) + SHA256_DIGEST_LENGTH,
 360                             EAP_CODE_REQUEST, id);
 361         if (req == NULL)
 362                 goto fin;
 363
 364         wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
 365         wpabuf_put_data(req, conf, SHA256_DIGEST_LENGTH);
 366
 367 fin:
 368         os_free(cruft);
 369         BN_free(x);
 370         BN_free(y);
 371         if (req == NULL)
 372                 eap_pwd_state(data, FAILURE);
 373
 374         return req;
 375 }
 376
 377
 378 static struct wpabuf *
 379 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
 380 {
 381         struct eap_pwd_data *data = priv;
 382
 383         switch (data->state) {
 384         case PWD_ID_Req:
 385                 return eap_pwd_build_id_req(sm, data, id);
 386         case PWD_Commit_Req:
 387                 return eap_pwd_build_commit_req(sm, data, id);
 388         case PWD_Confirm_Req:
 389                 return eap_pwd_build_confirm_req(sm, data, id);
 390         default:
 391                 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
 392                            data->state);
 393                 break;
 394         }
 395
 396         return NULL;
 397 }
 398
 399
 400 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
 401                              struct wpabuf *respData)
 402 {
 403         struct eap_pwd_data *data = priv;
 404         const u8 *pos;
 405         size_t len;
 406
 407         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 408         if (pos == NULL || len < 1) {
 409                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
 410                 return TRUE;
 411         }
 412
 413         wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: opcode=%d", *pos);
 414
 415         if (data->state == PWD_ID_Req && *pos == EAP_PWD_OPCODE_ID_EXCH)
 416                 return FALSE;
 417
 418         if (data->state == PWD_Commit_Req &&
 419             *pos == EAP_PWD_OPCODE_COMMIT_EXCH)
 420                 return FALSE;
 421
 422         if (data->state == PWD_Confirm_Req &&
 423             *pos == EAP_PWD_OPCODE_CONFIRM_EXCH)
 424                 return FALSE;
 425
 426         wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
 427                    *pos, data->state);
 428
 429         return TRUE;
 430 }
 431
 432
 433 static void eap_pwd_process_id_resp(struct eap_sm *sm,
 434                                     struct eap_pwd_data *data,
 435                                     const u8 *payload, size_t payload_len)
 436 {
 437         struct eap_pwd_id *id;
 438
 439         if (payload_len < sizeof(struct eap_pwd_id)) {
 440                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
 441                 return;
 442         }
 443
 444         id = (struct eap_pwd_id *) payload;
 445         if ((data->group_num != be_to_host16(id->group_num)) ||
 446             (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
 447             (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
 448             (id->prf != EAP_PWD_DEFAULT_PRF)) {
 449                 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
 450                 eap_pwd_state(data, FAILURE);
 451                 return;
 452         }
 453         data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
 454         if (data->id_peer == NULL) {
 455                 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
 456                 return;
 457         }
 458         data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
 459         os_memcpy(data->id_peer, id->identity, data->id_peer_len);
 460         wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
 461                           data->id_peer, data->id_peer_len);
 462
 463         if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == NULL) {
 464                 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
 465                            "group");
 466                 return;
 467         }
 468         if (compute_password_element(data->grp, data->group_num,
 469                                      data->password, data->password_len,
 470                                      data->id_server, data->id_server_len,
 471                                      data->id_peer, data->id_peer_len,
 472                                      (u8 *) &data->token)) {
 473                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
 474                            "PWE");
 475                 return;
 476         }
 477         wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
 478                    BN_num_bits(data->grp->prime));
 479
 480         eap_pwd_state(data, PWD_Commit_Req);
 481 }
 482
 483
 484 static void
 485 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 486                             const u8 *payload, size_t payload_len)
 487 {
 488         u8 *ptr;
 489         BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
 490         EC_POINT *K = NULL, *point = NULL;
 491         int res = 0;
 492
 493         wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
 494
 495         if (((data->peer_scalar = BN_new()) == NULL) ||
 496             ((data->k = BN_new()) == NULL) ||
 497             ((cofactor = BN_new()) == NULL) ||
 498             ((x = BN_new()) == NULL) ||
 499             ((y = BN_new()) == NULL) ||
 500             ((point = EC_POINT_new(data->grp->group)) == NULL) ||
 501             ((K = EC_POINT_new(data->grp->group)) == NULL) ||
 502             ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
 503                 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
 504                            "fail");
 505                 goto fin;
 506         }
 507
 508         if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
 509                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
 510                            "cofactor for curve");
 511                 goto fin;
 512         }
 513
 514         /* element, x then y, followed by scalar */
 515         ptr = (u8 *) payload;
 516         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
 517         ptr += BN_num_bytes(data->grp->prime);
 518         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
 519         ptr += BN_num_bytes(data->grp->prime);
 520         BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
 521         if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
 522                                                  data->peer_element, x, y,
 523                                                  bnctx)) {
 524                 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
 525                            "fail");
 526                 goto fin;
 527         }
 528
 529         /* check to ensure peer's element is not in a small sub-group */
 530         if (BN_cmp(cofactor, BN_value_one())) {
 531                 if (!EC_POINT_mul(data->grp->group, point, NULL,
 532                                   data->peer_element, cofactor, NULL)) {
 533                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 534                                    "multiply peer element by order");
 535                         goto fin;
 536                 }
 537                 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
 538                         wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
 539                                    "is at infinity!\n");
 540                         goto fin;
 541                 }
 542         }
 543
 544         /* compute the shared key, k */
 545         if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
 546                            data->peer_scalar, bnctx)) ||
 547             (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
 548                            bnctx)) ||
 549             (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
 550                            bnctx))) {
 551                 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
 552                            "fail");
 553                 goto fin;
 554         }
 555
 556         /* ensure that the shared key isn't in a small sub-group */
 557         if (BN_cmp(cofactor, BN_value_one())) {
 558                 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
 559                                   NULL)) {
 560                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 561                                    "multiply shared key point by order!\n");
 562                         goto fin;
 563                 }
 564         }
 565
 566         /*
 567          * This check is strictly speaking just for the case above where
 568          * co-factor > 1 but it was suggested that even though this is probably
 569          * never going to happen it is a simple and safe check "just to be
 570          * sure" so let's be safe.
 571          */
 572         if (EC_POINT_is_at_infinity(data->grp->group, K)) {
 573                 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
 574                            "at infinity");
 575                 goto fin;
 576         }
 577         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
 578                                                  NULL, bnctx)) {
 579                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
 580                            "shared secret from secret point");
 581                 goto fin;
 582         }
 583         res = 1;
 584
 585 fin:
 586         EC_POINT_free(K);
 587         EC_POINT_free(point);
 588         BN_free(cofactor);
 589         BN_free(x);
 590         BN_free(y);
 591
 592         if (res)
 593                 eap_pwd_state(data, PWD_Confirm_Req);
 594         else
 595                 eap_pwd_state(data, FAILURE);
 596 }
 597
 598
 599 static void
 600 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 601                              const u8 *payload, size_t payload_len)
 602 {
 603         BIGNUM *x = NULL, *y = NULL;
 604         HMAC_CTX ctx;
 605         u32 cs;
 606         u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;
 607
 608         /* build up the ciphersuite: group | random_function | prf */
 609         ptr = (u8 *) &cs;
 610         os_memcpy(ptr, &data->group_num, sizeof(u16));
 611         ptr += sizeof(u16);
 612         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 613         ptr += sizeof(u8);
 614         *ptr = EAP_PWD_DEFAULT_PRF;
 615
 616         /* each component of the cruft will be at most as big as the prime */
 617         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 618             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 619                 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
 620                 goto fin;
 621         }
 622
 623         /*
 624          * commit is H(k | peer_element | peer_scalar | server_element |
 625          *             server_scalar | ciphersuite)
 626          */
 627         H_Init(&ctx);
 628
 629         /* k */
 630         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 631         BN_bn2bin(data->k, cruft);
 632         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 633
 634         /* peer element: x, y */
 635         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 636                                                  data->peer_element, x, y,
 637                                                  bnctx)) {
 638                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 639                            "assignment fail");
 640                 goto fin;
 641         }
 642         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 643         BN_bn2bin(x, cruft);
 644         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 645         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 646         BN_bn2bin(y, cruft);
 647         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 648
 649         /* peer scalar */
 650         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 651         BN_bn2bin(data->peer_scalar, cruft);
 652         H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
 653
 654         /* server element: x, y */
 655         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 656                                                  data->my_element, x, y,
 657                                                  bnctx)) {
 658                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 659                            "assignment fail");
 660                 goto fin;
 661         }
 662
 663         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 664         BN_bn2bin(x, cruft);
 665         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 666         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 667         BN_bn2bin(y, cruft);
 668         H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
 669
 670         /* server scalar */
 671         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 672         BN_bn2bin(data->my_scalar, cruft);
 673         H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));
 674
 675         /* ciphersuite */
 676         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 677         H_Update(&ctx, (u8 *)&cs, sizeof(u32));
 678
 679         /* all done */
 680         H_Final(&ctx, conf);
 681
 682         ptr = (u8 *) payload;
 683         if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) {
 684                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
 685                            "verify");
 686                 goto fin;
 687         }
 688
 689         wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
 690         if (compute_keys(data->grp, bnctx, data->k, data->my_element,
 691                          data->peer_element, data->my_scalar,
 692                          data->peer_scalar, &cs, data->msk, data->emsk) < 0)
 693                 eap_pwd_state(data, FAILURE);
 694         else
 695                 eap_pwd_state(data, SUCCESS);
 696
 697 fin:
 698         os_free(cruft);
 699         BN_free(x);
 700         BN_free(y);
 701 }
 702
 703
 704 static void eap_pwd_process(struct eap_sm *sm, void *priv,
 705                             struct wpabuf *respData)
 706 {
 707         struct eap_pwd_data *data = priv;
 708         const u8 *pos;
 709         size_t len;
 710         u8 exch;
 711
 712         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 713         if ((pos == NULL) || (len < 1)) {
 714                 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
 715                            (pos == NULL) ? "is NULL" : "is not NULL",
 716                            (int) len);
 717                 return;
 718         }
 719
 720         exch = *pos & 0x3f;
 721         switch (exch) {
 722         case EAP_PWD_OPCODE_ID_EXCH:
 723                 eap_pwd_process_id_resp(sm, data, pos + 1, len - 1);
 724                 break;
 725         case EAP_PWD_OPCODE_COMMIT_EXCH:
 726                 eap_pwd_process_commit_resp(sm, data, pos + 1, len - 1);
 727                 break;
 728         case EAP_PWD_OPCODE_CONFIRM_EXCH:
 729                 eap_pwd_process_confirm_resp(sm, data, pos + 1, len - 1);
 730                 break;
 731         }
 732 }
 733
 734
 735 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
 736 {
 737         struct eap_pwd_data *data = priv;
 738         u8 *key;
 739
 740         if (data->state != SUCCESS)
 741                 return NULL;
 742
 743         key = os_malloc(EAP_MSK_LEN);
 744         if (key == NULL)
 745                 return NULL;
 746
 747         os_memcpy(key, data->msk, EAP_MSK_LEN);
 748         *len = EAP_MSK_LEN;
 749
 750         return key;
 751 }
 752
 753
 754 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 755 {
 756         struct eap_pwd_data *data = priv;
 757         u8 *key;
 758
 759         if (data->state != SUCCESS)
 760                 return NULL;
 761
 762         key = os_malloc(EAP_EMSK_LEN);
 763         if (key == NULL)
 764                 return NULL;
 765
 766         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
 767         *len = EAP_EMSK_LEN;
 768
 769         return key;
 770 }
 771
 772
 773 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
 774 {
 775         struct eap_pwd_data *data = priv;
 776         return data->state == SUCCESS;
 777 }
 778
 779
 780 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
 781 {
 782         struct eap_pwd_data *data = priv;
 783         return (data->state == SUCCESS) || (data->state == FAILURE);
 784 }
 785
 786
 787 int eap_server_pwd_register(void)
 788 {
 789         struct eap_method *eap;
 790         int ret;
 791         struct timeval tp;
 792         struct timezone tz;
 793         u32 sr;
 794
 795         EVP_add_digest(EVP_sha256());
 796
 797         sr = 0xdeaddada;
 798         (void) gettimeofday(&tp, &tz);
 799         sr ^= (tp.tv_sec ^ tp.tv_usec);
 800         srandom(sr);
 801
 802         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
 803                                       EAP_VENDOR_IETF, EAP_TYPE_PWD,
 804                                       "PWD");
 805         if (eap == NULL)
 806                 return -1;
 807
 808         eap->init = eap_pwd_init;
 809         eap->reset = eap_pwd_reset;
 810         eap->buildReq = eap_pwd_build_req;
 811         eap->check = eap_pwd_check;
 812         eap->process = eap_pwd_process;
 813         eap->isDone = eap_pwd_is_done;
 814         eap->getKey = eap_pwd_getkey;
 815         eap->get_emsk = eap_pwd_get_emsk;
 816         eap->isSuccess = eap_pwd_is_success;
 817
 818         ret = eap_server_method_register(eap);
 819         if (ret)
 820                 eap_server_method_free(eap);
 821         return ret;
 822 }
 823