1 /* 2 * hostapd / EAP-pwd (RFC 5931) server 3 * Copyright (c) 2010, Dan Harkins <dharkins (at) 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 my_confirm[SHA256_DIGEST_LENGTH]; 44 45 u8 msk[EAP_MSK_LEN]; 46 u8 emsk[EAP_EMSK_LEN]; 47 48 BN_CTX *bnctx; 49 }; 50 51 52 static const char * eap_pwd_state_txt(int state) 53 { 54 switch (state) { 55 case PWD_ID_Req: 56 return "PWD-ID-Req"; 57 case PWD_Commit_Req: 58 return "PWD-Commit-Req"; 59 case PWD_Confirm_Req: 60 return "PWD-Confirm-Req"; 61 case SUCCESS: 62 return "SUCCESS"; 63 case FAILURE: 64 return "FAILURE"; 65 default: 66 return "PWD-Unk"; 67 } 68 } 69 70 71 static void eap_pwd_state(struct eap_pwd_data *data, int state) 72 { 73 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s", 74 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); 75 data->state = state; 76 } 77 78 79 static void * eap_pwd_init(struct eap_sm *sm) 80 { 81 struct eap_pwd_data *data; 82 83 if (sm->user == NULL || sm->user->password == NULL || 84 sm->user->password_len == 0) { 85 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " 86 "configured"); 87 return NULL; 88 } 89 90 data = os_zalloc(sizeof(*data)); 91 if (data == NULL) 92 return NULL; 93 94 data->group_num = sm->pwd_group; 95 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", 96 data->group_num); 97 data->state = PWD_ID_Req; 98 99 data->id_server = (u8 *) os_strdup("server"); 100 if (data->id_server) 101 data->id_server_len = os_strlen((char *) data->id_server); 102 103 data->password = os_malloc(sm->user->password_len); 104 if (data->password == NULL) { 105 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " 106 "fail"); 107 os_free(data->id_server); 108 os_free(data); 109 return NULL; 110 } 111 data->password_len = sm->user->password_len; 112 os_memcpy(data->password, sm->user->password, data->password_len); 113 114 data->bnctx = BN_CTX_new(); 115 if (data->bnctx == NULL) { 116 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); 117 os_free(data->password); 118 os_free(data->id_server); 119 os_free(data); 120 return NULL; 121 } 122 123 return data; 124 } 125 126 127 static void eap_pwd_reset(struct eap_sm *sm, void *priv) 128 { 129 struct eap_pwd_data *data = priv; 130 131 BN_free(data->private_value); 132 BN_free(data->peer_scalar); 133 BN_free(data->my_scalar); 134 BN_free(data->k); 135 BN_CTX_free(data->bnctx); 136 EC_POINT_free(data->my_element); 137 EC_POINT_free(data->peer_element); 138 os_free(data->id_peer); 139 os_free(data->id_server); 140 os_free(data->password); 141 if (data->grp) { 142 EC_GROUP_free(data->grp->group); 143 EC_POINT_free(data->grp->pwe); 144 BN_free(data->grp->order); 145 BN_free(data->grp->prime); 146 os_free(data->grp); 147 } 148 os_free(data); 149 } 150 151 152 static struct wpabuf * 153 eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) 154 { 155 struct wpabuf *req; 156 157 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); 158 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 159 sizeof(struct eap_pwd_hdr) + 160 sizeof(struct eap_pwd_id) + data->id_server_len, 161 EAP_CODE_REQUEST, id); 162 if (req == NULL) { 163 eap_pwd_state(data, FAILURE); 164 return NULL; 165 } 166 167 /* an lfsr is good enough to generate unpredictable tokens */ 168 data->token = os_random(); 169 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 170 wpabuf_put_be16(req, data->group_num); 171 wpabuf_put_u8(req, EAP_PWD_DEFAULT_RAND_FUNC); 172 wpabuf_put_u8(req, EAP_PWD_DEFAULT_PRF); 173 wpabuf_put_data(req, &data->token, sizeof(data->token)); 174 wpabuf_put_u8(req, EAP_PWD_PREP_NONE); 175 wpabuf_put_data(req, data->id_server, data->id_server_len); 176 177 return req; 178 } 179 180 181 static struct wpabuf * 182 eap_pwd_build_commit_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) 183 { 184 struct wpabuf *req = NULL; 185 BIGNUM *mask = NULL, *x = NULL, *y = NULL; 186 u8 *scalar = NULL, *element = NULL; 187 u16 offset; 188 189 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 190 191 if (((data->private_value = BN_new()) == NULL) || 192 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 193 ((data->my_scalar = BN_new()) == NULL) || 194 ((mask = BN_new()) == NULL)) { 195 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 196 "fail"); 197 goto fin; 198 } 199 200 BN_rand_range(data->private_value, data->grp->order); 201 BN_rand_range(mask, data->grp->order); 202 BN_add(data->my_scalar, data->private_value, mask); 203 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 204 data->bnctx); 205 206 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 207 data->grp->pwe, mask, data->bnctx)) { 208 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 209 "fail"); 210 eap_pwd_state(data, FAILURE); 211 goto fin; 212 } 213 214 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 215 { 216 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 217 "fail"); 218 goto fin; 219 } 220 BN_free(mask); 221 222 if (((x = BN_new()) == NULL) || 223 ((y = BN_new()) == NULL)) { 224 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 225 "fail"); 226 goto fin; 227 } 228 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 229 data->my_element, x, y, 230 data->bnctx)) { 231 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 232 "fail"); 233 goto fin; 234 } 235 236 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 237 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 238 NULL)) { 239 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 240 goto fin; 241 } 242 243 /* 244 * bignums occupy as little memory as possible so one that is 245 * sufficiently smaller than the prime or order might need pre-pending 246 * with zeros. 247 */ 248 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 249 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 250 offset = BN_num_bytes(data->grp->order) - 251 BN_num_bytes(data->my_scalar); 252 BN_bn2bin(data->my_scalar, scalar + offset); 253 254 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 255 BN_bn2bin(x, element + offset); 256 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 257 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 258 259 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 260 sizeof(struct eap_pwd_hdr) + 261 (2 * BN_num_bytes(data->grp->prime)) + 262 BN_num_bytes(data->grp->order), 263 EAP_CODE_REQUEST, id); 264 if (req == NULL) 265 goto fin; 266 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 267 268 /* We send the element as (x,y) followed by the scalar */ 269 wpabuf_put_data(req, element, (2 * BN_num_bytes(data->grp->prime))); 270 wpabuf_put_data(req, scalar, BN_num_bytes(data->grp->order)); 271 272 fin: 273 os_free(scalar); 274 os_free(element); 275 BN_free(x); 276 BN_free(y); 277 if (req == NULL) 278 eap_pwd_state(data, FAILURE); 279 280 return req; 281 } 282 283 284 static struct wpabuf * 285 eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) 286 { 287 struct wpabuf *req = NULL; 288 BIGNUM *x = NULL, *y = NULL; 289 HMAC_CTX ctx; 290 u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr; 291 u16 grp; 292 293 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 294 295 /* Each component of the cruft will be at most as big as the prime */ 296 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 297 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 298 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 299 "fail"); 300 goto fin; 301 } 302 303 /* 304 * commit is H(k | server_element | server_scalar | peer_element | 305 * peer_scalar | ciphersuite) 306 */ 307 H_Init(&ctx); 308 309 /* 310 * Zero the memory each time because this is mod prime math and some 311 * value may start with a few zeros and the previous one did not. 312 * 313 * First is k 314 */ 315 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 316 BN_bn2bin(data->k, cruft); 317 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 318 319 /* server element: x, y */ 320 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 321 data->my_element, x, y, 322 data->bnctx)) { 323 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 324 "assignment fail"); 325 goto fin; 326 } 327 328 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 329 BN_bn2bin(x, cruft); 330 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 331 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 332 BN_bn2bin(y, cruft); 333 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 334 335 /* server scalar */ 336 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 337 BN_bn2bin(data->my_scalar, cruft); 338 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 339 340 /* peer element: x, y */ 341 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 342 data->peer_element, x, y, 343 data->bnctx)) { 344 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 345 "assignment fail"); 346 goto fin; 347 } 348 349 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 350 BN_bn2bin(x, cruft); 351 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 352 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 353 BN_bn2bin(y, cruft); 354 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 355 356 /* peer scalar */ 357 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 358 BN_bn2bin(data->peer_scalar, cruft); 359 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 360 361 /* ciphersuite */ 362 grp = htons(data->group_num); 363 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 364 ptr = cruft; 365 os_memcpy(ptr, &grp, sizeof(u16)); 366 ptr += sizeof(u16); 367 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 368 ptr += sizeof(u8); 369 *ptr = EAP_PWD_DEFAULT_PRF; 370 ptr += sizeof(u8); 371 H_Update(&ctx, cruft, ptr-cruft); 372 373 /* all done with the random function */ 374 H_Final(&ctx, conf); 375 os_memcpy(data->my_confirm, conf, SHA256_DIGEST_LENGTH); 376 377 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 378 sizeof(struct eap_pwd_hdr) + SHA256_DIGEST_LENGTH, 379 EAP_CODE_REQUEST, id); 380 if (req == NULL) 381 goto fin; 382 383 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 384 wpabuf_put_data(req, conf, SHA256_DIGEST_LENGTH); 385 386 fin: 387 os_free(cruft); 388 BN_free(x); 389 BN_free(y); 390 if (req == NULL) 391 eap_pwd_state(data, FAILURE); 392 393 return req; 394 } 395 396 397 static struct wpabuf * 398 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 399 { 400 struct eap_pwd_data *data = priv; 401 402 switch (data->state) { 403 case PWD_ID_Req: 404 return eap_pwd_build_id_req(sm, data, id); 405 case PWD_Commit_Req: 406 return eap_pwd_build_commit_req(sm, data, id); 407 case PWD_Confirm_Req: 408 return eap_pwd_build_confirm_req(sm, data, id); 409 default: 410 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 411 data->state); 412 break; 413 } 414 415 return NULL; 416 } 417 418 419 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 420 struct wpabuf *respData) 421 { 422 struct eap_pwd_data *data = priv; 423 const u8 *pos; 424 size_t len; 425 426 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 427 if (pos == NULL || len < 1) { 428 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 429 return TRUE; 430 } 431 432 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: opcode=%d", *pos); 433 434 if (data->state == PWD_ID_Req && *pos == EAP_PWD_OPCODE_ID_EXCH) 435 return FALSE; 436 437 if (data->state == PWD_Commit_Req && 438 *pos == EAP_PWD_OPCODE_COMMIT_EXCH) 439 return FALSE; 440 441 if (data->state == PWD_Confirm_Req && 442 *pos == EAP_PWD_OPCODE_CONFIRM_EXCH) 443 return FALSE; 444 445 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 446 *pos, data->state); 447 448 return TRUE; 449 } 450 451 452 static void eap_pwd_process_id_resp(struct eap_sm *sm, 453 struct eap_pwd_data *data, 454 const u8 *payload, size_t payload_len) 455 { 456 struct eap_pwd_id *id; 457 458 if (payload_len < sizeof(struct eap_pwd_id)) { 459 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 460 return; 461 } 462 463 id = (struct eap_pwd_id *) payload; 464 if ((data->group_num != be_to_host16(id->group_num)) || 465 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 466 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 467 (id->prf != EAP_PWD_DEFAULT_PRF)) { 468 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 469 eap_pwd_state(data, FAILURE); 470 return; 471 } 472 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 473 if (data->id_peer == NULL) { 474 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 475 return; 476 } 477 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 478 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 479 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 480 data->id_peer, data->id_peer_len); 481 482 if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == NULL) { 483 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 484 "group"); 485 return; 486 } 487 if (compute_password_element(data->grp, data->group_num, 488 data->password, data->password_len, 489 data->id_server, data->id_server_len, 490 data->id_peer, data->id_peer_len, 491 (u8 *) &data->token)) { 492 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 493 "PWE"); 494 return; 495 } 496 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 497 BN_num_bits(data->grp->prime)); 498 499 eap_pwd_state(data, PWD_Commit_Req); 500 } 501 502 503 static void 504 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 505 const u8 *payload, size_t payload_len) 506 { 507 u8 *ptr; 508 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 509 EC_POINT *K = NULL, *point = NULL; 510 int res = 0; 511 512 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 513 514 if (((data->peer_scalar = BN_new()) == NULL) || 515 ((data->k = BN_new()) == NULL) || 516 ((cofactor = BN_new()) == NULL) || 517 ((x = BN_new()) == NULL) || 518 ((y = BN_new()) == NULL) || 519 ((point = EC_POINT_new(data->grp->group)) == NULL) || 520 ((K = EC_POINT_new(data->grp->group)) == NULL) || 521 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 522 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 523 "fail"); 524 goto fin; 525 } 526 527 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 528 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 529 "cofactor for curve"); 530 goto fin; 531 } 532 533 /* element, x then y, followed by scalar */ 534 ptr = (u8 *) payload; 535 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 536 ptr += BN_num_bytes(data->grp->prime); 537 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 538 ptr += BN_num_bytes(data->grp->prime); 539 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 540 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 541 data->peer_element, x, y, 542 data->bnctx)) { 543 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 544 "fail"); 545 goto fin; 546 } 547 548 /* check to ensure peer's element is not in a small sub-group */ 549 if (BN_cmp(cofactor, BN_value_one())) { 550 if (!EC_POINT_mul(data->grp->group, point, NULL, 551 data->peer_element, cofactor, NULL)) { 552 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 553 "multiply peer element by order"); 554 goto fin; 555 } 556 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 557 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 558 "is at infinity!\n"); 559 goto fin; 560 } 561 } 562 563 /* compute the shared key, k */ 564 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 565 data->peer_scalar, data->bnctx)) || 566 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 567 data->bnctx)) || 568 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 569 data->bnctx))) { 570 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 571 "fail"); 572 goto fin; 573 } 574 575 /* ensure that the shared key isn't in a small sub-group */ 576 if (BN_cmp(cofactor, BN_value_one())) { 577 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 578 NULL)) { 579 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 580 "multiply shared key point by order!\n"); 581 goto fin; 582 } 583 } 584 585 /* 586 * This check is strictly speaking just for the case above where 587 * co-factor > 1 but it was suggested that even though this is probably 588 * never going to happen it is a simple and safe check "just to be 589 * sure" so let's be safe. 590 */ 591 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 592 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 593 "at infinity"); 594 goto fin; 595 } 596 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 597 NULL, data->bnctx)) { 598 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 599 "shared secret from secret point"); 600 goto fin; 601 } 602 res = 1; 603 604 fin: 605 EC_POINT_free(K); 606 EC_POINT_free(point); 607 BN_free(cofactor); 608 BN_free(x); 609 BN_free(y); 610 611 if (res) 612 eap_pwd_state(data, PWD_Confirm_Req); 613 else 614 eap_pwd_state(data, FAILURE); 615 } 616 617 618 static void 619 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 620 const u8 *payload, size_t payload_len) 621 { 622 BIGNUM *x = NULL, *y = NULL; 623 HMAC_CTX ctx; 624 u32 cs; 625 u16 grp; 626 u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr; 627 628 /* build up the ciphersuite: group | random_function | prf */ 629 grp = htons(data->group_num); 630 ptr = (u8 *) &cs; 631 os_memcpy(ptr, &grp, sizeof(u16)); 632 ptr += sizeof(u16); 633 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 634 ptr += sizeof(u8); 635 *ptr = EAP_PWD_DEFAULT_PRF; 636 637 /* each component of the cruft will be at most as big as the prime */ 638 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 639 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 640 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 641 goto fin; 642 } 643 644 /* 645 * commit is H(k | peer_element | peer_scalar | server_element | 646 * server_scalar | ciphersuite) 647 */ 648 H_Init(&ctx); 649 650 /* k */ 651 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 652 BN_bn2bin(data->k, cruft); 653 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 654 655 /* peer element: x, y */ 656 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 657 data->peer_element, x, y, 658 data->bnctx)) { 659 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 660 "assignment fail"); 661 goto fin; 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 /* peer scalar */ 671 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 672 BN_bn2bin(data->peer_scalar, cruft); 673 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 674 675 /* server element: x, y */ 676 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 677 data->my_element, x, y, 678 data->bnctx)) { 679 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 680 "assignment fail"); 681 goto fin; 682 } 683 684 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 685 BN_bn2bin(x, cruft); 686 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 687 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 688 BN_bn2bin(y, cruft); 689 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 690 691 /* server scalar */ 692 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 693 BN_bn2bin(data->my_scalar, cruft); 694 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 695 696 /* ciphersuite */ 697 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 698 H_Update(&ctx, (u8 *)&cs, sizeof(u32)); 699 700 /* all done */ 701 H_Final(&ctx, conf); 702 703 ptr = (u8 *) payload; 704 if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) { 705 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 706 "verify"); 707 goto fin; 708 } 709 710 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 711 if (compute_keys(data->grp, data->bnctx, data->k, 712 data->peer_scalar, data->my_scalar, conf, 713 data->my_confirm, &cs, data->msk, data->emsk) < 0) 714 eap_pwd_state(data, FAILURE); 715 else 716 eap_pwd_state(data, SUCCESS); 717 718 fin: 719 os_free(cruft); 720 BN_free(x); 721 BN_free(y); 722 } 723 724 725 static void eap_pwd_process(struct eap_sm *sm, void *priv, 726 struct wpabuf *respData) 727 { 728 struct eap_pwd_data *data = priv; 729 const u8 *pos; 730 size_t len; 731 u8 exch; 732 733 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 734 if ((pos == NULL) || (len < 1)) { 735 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 736 (pos == NULL) ? "is NULL" : "is not NULL", 737 (int) len); 738 return; 739 } 740 741 exch = *pos & 0x3f; 742 switch (exch) { 743 case EAP_PWD_OPCODE_ID_EXCH: 744 eap_pwd_process_id_resp(sm, data, pos + 1, len - 1); 745 break; 746 case EAP_PWD_OPCODE_COMMIT_EXCH: 747 eap_pwd_process_commit_resp(sm, data, pos + 1, len - 1); 748 break; 749 case EAP_PWD_OPCODE_CONFIRM_EXCH: 750 eap_pwd_process_confirm_resp(sm, data, pos + 1, len - 1); 751 break; 752 } 753 } 754 755 756 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 757 { 758 struct eap_pwd_data *data = priv; 759 u8 *key; 760 761 if (data->state != SUCCESS) 762 return NULL; 763 764 key = os_malloc(EAP_MSK_LEN); 765 if (key == NULL) 766 return NULL; 767 768 os_memcpy(key, data->msk, EAP_MSK_LEN); 769 *len = EAP_MSK_LEN; 770 771 return key; 772 } 773 774 775 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 776 { 777 struct eap_pwd_data *data = priv; 778 u8 *key; 779 780 if (data->state != SUCCESS) 781 return NULL; 782 783 key = os_malloc(EAP_EMSK_LEN); 784 if (key == NULL) 785 return NULL; 786 787 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 788 *len = EAP_EMSK_LEN; 789 790 return key; 791 } 792 793 794 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 795 { 796 struct eap_pwd_data *data = priv; 797 return data->state == SUCCESS; 798 } 799 800 801 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 802 { 803 struct eap_pwd_data *data = priv; 804 return (data->state == SUCCESS) || (data->state == FAILURE); 805 } 806 807 808 int eap_server_pwd_register(void) 809 { 810 struct eap_method *eap; 811 int ret; 812 struct timeval tp; 813 struct timezone tz; 814 u32 sr; 815 816 EVP_add_digest(EVP_sha256()); 817 818 sr = 0xdeaddada; 819 (void) gettimeofday(&tp, &tz); 820 sr ^= (tp.tv_sec ^ tp.tv_usec); 821 srandom(sr); 822 823 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 824 EAP_VENDOR_IETF, EAP_TYPE_PWD, 825 "PWD"); 826 if (eap == NULL) 827 return -1; 828 829 eap->init = eap_pwd_init; 830 eap->reset = eap_pwd_reset; 831 eap->buildReq = eap_pwd_build_req; 832 eap->check = eap_pwd_check; 833 eap->process = eap_pwd_process; 834 eap->isDone = eap_pwd_is_done; 835 eap->getKey = eap_pwd_getkey; 836 eap->get_emsk = eap_pwd_get_emsk; 837 eap->isSuccess = eap_pwd_is_success; 838 839 ret = eap_server_method_register(eap); 840 if (ret) 841 eap_server_method_free(eap); 842 return ret; 843 } 844 845
