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 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 int offset; 293 294 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 295 296 /* Each component of the cruft will be at most as big as the prime */ 297 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 298 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 299 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 300 "fail"); 301 goto fin; 302 } 303 304 /* 305 * commit is H(k | server_element | server_scalar | peer_element | 306 * peer_scalar | ciphersuite) 307 */ 308 H_Init(&ctx); 309 310 /* 311 * Zero the memory each time because this is mod prime math and some 312 * value may start with a few zeros and the previous one did not. 313 * 314 * First is k 315 */ 316 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 317 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 318 BN_bn2bin(data->k, cruft + offset); 319 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 320 321 /* server element: x, y */ 322 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 323 data->my_element, x, y, 324 data->bnctx)) { 325 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 326 "assignment fail"); 327 goto fin; 328 } 329 330 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 331 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 332 BN_bn2bin(x, cruft + offset); 333 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 334 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 335 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 336 BN_bn2bin(y, cruft + offset); 337 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 338 339 /* server scalar */ 340 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 341 offset = BN_num_bytes(data->grp->order) - 342 BN_num_bytes(data->my_scalar); 343 BN_bn2bin(data->my_scalar, cruft + offset); 344 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 345 346 /* peer element: x, y */ 347 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 348 data->peer_element, x, y, 349 data->bnctx)) { 350 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 351 "assignment fail"); 352 goto fin; 353 } 354 355 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 356 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 357 BN_bn2bin(x, cruft + offset); 358 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 359 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 360 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 361 BN_bn2bin(y, cruft + offset); 362 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 363 364 /* peer scalar */ 365 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 366 offset = BN_num_bytes(data->grp->order) - 367 BN_num_bytes(data->peer_scalar); 368 BN_bn2bin(data->peer_scalar, cruft + offset); 369 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 370 371 /* ciphersuite */ 372 grp = htons(data->group_num); 373 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 374 ptr = cruft; 375 os_memcpy(ptr, &grp, sizeof(u16)); 376 ptr += sizeof(u16); 377 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 378 ptr += sizeof(u8); 379 *ptr = EAP_PWD_DEFAULT_PRF; 380 ptr += sizeof(u8); 381 H_Update(&ctx, cruft, ptr-cruft); 382 383 /* all done with the random function */ 384 H_Final(&ctx, conf); 385 os_memcpy(data->my_confirm, conf, SHA256_DIGEST_LENGTH); 386 387 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 388 sizeof(struct eap_pwd_hdr) + SHA256_DIGEST_LENGTH, 389 EAP_CODE_REQUEST, id); 390 if (req == NULL) 391 goto fin; 392 393 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 394 wpabuf_put_data(req, conf, SHA256_DIGEST_LENGTH); 395 396 fin: 397 os_free(cruft); 398 BN_free(x); 399 BN_free(y); 400 if (req == NULL) 401 eap_pwd_state(data, FAILURE); 402 403 return req; 404 } 405 406 407 static struct wpabuf * 408 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 409 { 410 struct eap_pwd_data *data = priv; 411 412 switch (data->state) { 413 case PWD_ID_Req: 414 return eap_pwd_build_id_req(sm, data, id); 415 case PWD_Commit_Req: 416 return eap_pwd_build_commit_req(sm, data, id); 417 case PWD_Confirm_Req: 418 return eap_pwd_build_confirm_req(sm, data, id); 419 default: 420 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 421 data->state); 422 break; 423 } 424 425 return NULL; 426 } 427 428 429 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 430 struct wpabuf *respData) 431 { 432 struct eap_pwd_data *data = priv; 433 const u8 *pos; 434 size_t len; 435 436 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 437 if (pos == NULL || len < 1) { 438 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 439 return TRUE; 440 } 441 442 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: opcode=%d", *pos); 443 444 if (data->state == PWD_ID_Req && *pos == EAP_PWD_OPCODE_ID_EXCH) 445 return FALSE; 446 447 if (data->state == PWD_Commit_Req && 448 *pos == EAP_PWD_OPCODE_COMMIT_EXCH) 449 return FALSE; 450 451 if (data->state == PWD_Confirm_Req && 452 *pos == EAP_PWD_OPCODE_CONFIRM_EXCH) 453 return FALSE; 454 455 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 456 *pos, data->state); 457 458 return TRUE; 459 } 460 461 462 static void eap_pwd_process_id_resp(struct eap_sm *sm, 463 struct eap_pwd_data *data, 464 const u8 *payload, size_t payload_len) 465 { 466 struct eap_pwd_id *id; 467 468 if (payload_len < sizeof(struct eap_pwd_id)) { 469 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 470 return; 471 } 472 473 id = (struct eap_pwd_id *) payload; 474 if ((data->group_num != be_to_host16(id->group_num)) || 475 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 476 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 477 (id->prf != EAP_PWD_DEFAULT_PRF)) { 478 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 479 eap_pwd_state(data, FAILURE); 480 return; 481 } 482 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 483 if (data->id_peer == NULL) { 484 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 485 return; 486 } 487 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 488 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 489 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 490 data->id_peer, data->id_peer_len); 491 492 if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == NULL) { 493 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 494 "group"); 495 return; 496 } 497 if (compute_password_element(data->grp, data->group_num, 498 data->password, data->password_len, 499 data->id_server, data->id_server_len, 500 data->id_peer, data->id_peer_len, 501 (u8 *) &data->token)) { 502 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 503 "PWE"); 504 return; 505 } 506 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 507 BN_num_bits(data->grp->prime)); 508 509 eap_pwd_state(data, PWD_Commit_Req); 510 } 511 512 513 static void 514 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 515 const u8 *payload, size_t payload_len) 516 { 517 u8 *ptr; 518 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 519 EC_POINT *K = NULL, *point = NULL; 520 int res = 0; 521 522 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 523 524 if (((data->peer_scalar = BN_new()) == NULL) || 525 ((data->k = BN_new()) == NULL) || 526 ((cofactor = BN_new()) == NULL) || 527 ((x = BN_new()) == NULL) || 528 ((y = BN_new()) == NULL) || 529 ((point = EC_POINT_new(data->grp->group)) == NULL) || 530 ((K = EC_POINT_new(data->grp->group)) == NULL) || 531 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 532 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 533 "fail"); 534 goto fin; 535 } 536 537 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 538 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 539 "cofactor for curve"); 540 goto fin; 541 } 542 543 /* element, x then y, followed by scalar */ 544 ptr = (u8 *) payload; 545 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 546 ptr += BN_num_bytes(data->grp->prime); 547 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 548 ptr += BN_num_bytes(data->grp->prime); 549 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 550 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 551 data->peer_element, x, y, 552 data->bnctx)) { 553 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 554 "fail"); 555 goto fin; 556 } 557 558 /* check to ensure peer's element is not in a small sub-group */ 559 if (BN_cmp(cofactor, BN_value_one())) { 560 if (!EC_POINT_mul(data->grp->group, point, NULL, 561 data->peer_element, cofactor, NULL)) { 562 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 563 "multiply peer element by order"); 564 goto fin; 565 } 566 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 567 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 568 "is at infinity!\n"); 569 goto fin; 570 } 571 } 572 573 /* compute the shared key, k */ 574 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 575 data->peer_scalar, data->bnctx)) || 576 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 577 data->bnctx)) || 578 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 579 data->bnctx))) { 580 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 581 "fail"); 582 goto fin; 583 } 584 585 /* ensure that the shared key isn't in a small sub-group */ 586 if (BN_cmp(cofactor, BN_value_one())) { 587 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 588 NULL)) { 589 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 590 "multiply shared key point by order!\n"); 591 goto fin; 592 } 593 } 594 595 /* 596 * This check is strictly speaking just for the case above where 597 * co-factor > 1 but it was suggested that even though this is probably 598 * never going to happen it is a simple and safe check "just to be 599 * sure" so let's be safe. 600 */ 601 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 602 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 603 "at infinity"); 604 goto fin; 605 } 606 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 607 NULL, data->bnctx)) { 608 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 609 "shared secret from secret point"); 610 goto fin; 611 } 612 res = 1; 613 614 fin: 615 EC_POINT_free(K); 616 EC_POINT_free(point); 617 BN_free(cofactor); 618 BN_free(x); 619 BN_free(y); 620 621 if (res) 622 eap_pwd_state(data, PWD_Confirm_Req); 623 else 624 eap_pwd_state(data, FAILURE); 625 } 626 627 628 static void 629 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 630 const u8 *payload, size_t payload_len) 631 { 632 BIGNUM *x = NULL, *y = NULL; 633 HMAC_CTX ctx; 634 u32 cs; 635 u16 grp; 636 u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr; 637 int offset; 638 639 /* build up the ciphersuite: group | random_function | prf */ 640 grp = htons(data->group_num); 641 ptr = (u8 *) &cs; 642 os_memcpy(ptr, &grp, sizeof(u16)); 643 ptr += sizeof(u16); 644 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 645 ptr += sizeof(u8); 646 *ptr = EAP_PWD_DEFAULT_PRF; 647 648 /* each component of the cruft will be at most as big as the prime */ 649 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 650 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 651 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 652 goto fin; 653 } 654 655 /* 656 * commit is H(k | peer_element | peer_scalar | server_element | 657 * server_scalar | ciphersuite) 658 */ 659 H_Init(&ctx); 660 661 /* k */ 662 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 663 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 664 BN_bn2bin(data->k, cruft + offset); 665 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 666 667 /* peer element: x, y */ 668 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 669 data->peer_element, x, y, 670 data->bnctx)) { 671 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 672 "assignment fail"); 673 goto fin; 674 } 675 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 676 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 677 BN_bn2bin(x, cruft + offset); 678 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 679 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 680 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 681 BN_bn2bin(y, cruft + offset); 682 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 683 684 /* peer scalar */ 685 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 686 offset = BN_num_bytes(data->grp->order) - 687 BN_num_bytes(data->peer_scalar); 688 BN_bn2bin(data->peer_scalar, cruft + offset); 689 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 690 691 /* server element: x, y */ 692 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 693 data->my_element, x, y, 694 data->bnctx)) { 695 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 696 "assignment fail"); 697 goto fin; 698 } 699 700 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 701 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 702 BN_bn2bin(x, cruft + offset); 703 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 704 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 705 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 706 BN_bn2bin(y, cruft + offset); 707 H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime)); 708 709 /* server scalar */ 710 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 711 offset = BN_num_bytes(data->grp->order) - 712 BN_num_bytes(data->my_scalar); 713 BN_bn2bin(data->my_scalar, cruft + offset); 714 H_Update(&ctx, cruft, BN_num_bytes(data->grp->order)); 715 716 /* ciphersuite */ 717 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 718 H_Update(&ctx, (u8 *)&cs, sizeof(u32)); 719 720 /* all done */ 721 H_Final(&ctx, conf); 722 723 ptr = (u8 *) payload; 724 if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) { 725 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 726 "verify"); 727 goto fin; 728 } 729 730 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 731 if (compute_keys(data->grp, data->bnctx, data->k, 732 data->peer_scalar, data->my_scalar, conf, 733 data->my_confirm, &cs, data->msk, data->emsk) < 0) 734 eap_pwd_state(data, FAILURE); 735 else 736 eap_pwd_state(data, SUCCESS); 737 738 fin: 739 os_free(cruft); 740 BN_free(x); 741 BN_free(y); 742 } 743 744 745 static void eap_pwd_process(struct eap_sm *sm, void *priv, 746 struct wpabuf *respData) 747 { 748 struct eap_pwd_data *data = priv; 749 const u8 *pos; 750 size_t len; 751 u8 exch; 752 753 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 754 if ((pos == NULL) || (len < 1)) { 755 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 756 (pos == NULL) ? "is NULL" : "is not NULL", 757 (int) len); 758 return; 759 } 760 761 exch = *pos & 0x3f; 762 switch (exch) { 763 case EAP_PWD_OPCODE_ID_EXCH: 764 eap_pwd_process_id_resp(sm, data, pos + 1, len - 1); 765 break; 766 case EAP_PWD_OPCODE_COMMIT_EXCH: 767 eap_pwd_process_commit_resp(sm, data, pos + 1, len - 1); 768 break; 769 case EAP_PWD_OPCODE_CONFIRM_EXCH: 770 eap_pwd_process_confirm_resp(sm, data, pos + 1, len - 1); 771 break; 772 } 773 } 774 775 776 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 777 { 778 struct eap_pwd_data *data = priv; 779 u8 *key; 780 781 if (data->state != SUCCESS) 782 return NULL; 783 784 key = os_malloc(EAP_MSK_LEN); 785 if (key == NULL) 786 return NULL; 787 788 os_memcpy(key, data->msk, EAP_MSK_LEN); 789 *len = EAP_MSK_LEN; 790 791 return key; 792 } 793 794 795 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 796 { 797 struct eap_pwd_data *data = priv; 798 u8 *key; 799 800 if (data->state != SUCCESS) 801 return NULL; 802 803 key = os_malloc(EAP_EMSK_LEN); 804 if (key == NULL) 805 return NULL; 806 807 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 808 *len = EAP_EMSK_LEN; 809 810 return key; 811 } 812 813 814 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 815 { 816 struct eap_pwd_data *data = priv; 817 return data->state == SUCCESS; 818 } 819 820 821 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 822 { 823 struct eap_pwd_data *data = priv; 824 return (data->state == SUCCESS) || (data->state == FAILURE); 825 } 826 827 828 int eap_server_pwd_register(void) 829 { 830 struct eap_method *eap; 831 int ret; 832 struct timeval tp; 833 struct timezone tz; 834 u32 sr; 835 836 EVP_add_digest(EVP_sha256()); 837 838 sr = 0xdeaddada; 839 (void) gettimeofday(&tp, &tz); 840 sr ^= (tp.tv_sec ^ tp.tv_usec); 841 srandom(sr); 842 843 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 844 EAP_VENDOR_IETF, EAP_TYPE_PWD, 845 "PWD"); 846 if (eap == NULL) 847 return -1; 848 849 eap->init = eap_pwd_init; 850 eap->reset = eap_pwd_reset; 851 eap->buildReq = eap_pwd_build_req; 852 eap->check = eap_pwd_check; 853 eap->process = eap_pwd_process; 854 eap->isDone = eap_pwd_is_done; 855 eap->getKey = eap_pwd_getkey; 856 eap->get_emsk = eap_pwd_get_emsk; 857 eap->isSuccess = eap_pwd_is_success; 858 859 ret = eap_server_method_register(eap); 860 if (ret) 861 eap_server_method_free(eap); 862 return ret; 863 } 864 865