1 /* 2 * hostapd / EAP-pwd (RFC 5931) server 3 * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org> 4 * 5 * This software may be distributed under the terms of the BSD license. 6 * See README for more details. 7 */ 8 9 #include "includes.h" 10 11 #include "common.h" 12 #include "crypto/sha256.h" 13 #include "crypto/ms_funcs.h" 14 #include "crypto/crypto.h" 15 #include "eap_server/eap_i.h" 16 #include "eap_common/eap_pwd_common.h" 17 18 19 struct eap_pwd_data { 20 enum { 21 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE 22 } state; 23 u8 *id_peer; 24 size_t id_peer_len; 25 u8 *id_server; 26 size_t id_server_len; 27 u8 *password; 28 size_t password_len; 29 int password_hash; 30 u8 *salt; 31 size_t salt_len; 32 u32 token; 33 u16 group_num; 34 u8 password_prep; 35 EAP_PWD_group *grp; 36 37 struct wpabuf *inbuf; 38 size_t in_frag_pos; 39 struct wpabuf *outbuf; 40 size_t out_frag_pos; 41 size_t mtu; 42 43 struct crypto_bignum *k; 44 struct crypto_bignum *private_value; 45 struct crypto_bignum *peer_scalar; 46 struct crypto_bignum *my_scalar; 47 struct crypto_ec_point *my_element; 48 struct crypto_ec_point *peer_element; 49 50 u8 my_confirm[SHA256_MAC_LEN]; 51 52 u8 msk[EAP_MSK_LEN]; 53 u8 emsk[EAP_EMSK_LEN]; 54 u8 session_id[1 + SHA256_MAC_LEN]; 55 }; 56 57 58 static const char * eap_pwd_state_txt(int state) 59 { 60 switch (state) { 61 case PWD_ID_Req: 62 return "PWD-ID-Req"; 63 case PWD_Commit_Req: 64 return "PWD-Commit-Req"; 65 case PWD_Confirm_Req: 66 return "PWD-Confirm-Req"; 67 case SUCCESS: 68 return "SUCCESS"; 69 case FAILURE: 70 return "FAILURE"; 71 default: 72 return "PWD-Unk"; 73 } 74 } 75 76 77 static void eap_pwd_state(struct eap_pwd_data *data, int state) 78 { 79 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s", 80 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); 81 data->state = state; 82 } 83 84 85 static void * eap_pwd_init(struct eap_sm *sm) 86 { 87 struct eap_pwd_data *data; 88 89 if (sm->user == NULL || sm->user->password == NULL || 90 sm->user->password_len == 0) { 91 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " 92 "configured"); 93 return NULL; 94 } 95 96 data = os_zalloc(sizeof(*data)); 97 if (data == NULL) 98 return NULL; 99 100 data->group_num = sm->pwd_group; 101 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", 102 data->group_num); 103 data->state = PWD_ID_Req; 104 105 data->id_server = (u8 *) os_strdup("server"); 106 if (data->id_server) 107 data->id_server_len = os_strlen((char *) data->id_server); 108 109 data->password = os_malloc(sm->user->password_len); 110 if (data->password == NULL) { 111 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " 112 "fail"); 113 bin_clear_free(data->id_server, data->id_server_len); 114 os_free(data); 115 return NULL; 116 } 117 data->password_len = sm->user->password_len; 118 os_memcpy(data->password, sm->user->password, data->password_len); 119 data->password_hash = sm->user->password_hash; 120 121 data->salt_len = sm->user->salt_len; 122 if (data->salt_len) { 123 data->salt = os_memdup(sm->user->salt, sm->user->salt_len); 124 if (!data->salt) { 125 wpa_printf(MSG_INFO, 126 "EAP-pwd: Memory allocation of salt failed"); 127 bin_clear_free(data->id_server, data->id_server_len); 128 bin_clear_free(data->password, data->password_len); 129 os_free(data); 130 return NULL; 131 } 132 } 133 134 data->in_frag_pos = data->out_frag_pos = 0; 135 data->inbuf = data->outbuf = NULL; 136 /* use default MTU from RFC 5931 if not configured otherwise */ 137 data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020; 138 139 return data; 140 } 141 142 143 static void eap_pwd_reset(struct eap_sm *sm, void *priv) 144 { 145 struct eap_pwd_data *data = priv; 146 147 crypto_bignum_deinit(data->private_value, 1); 148 crypto_bignum_deinit(data->peer_scalar, 1); 149 crypto_bignum_deinit(data->my_scalar, 1); 150 crypto_bignum_deinit(data->k, 1); 151 crypto_ec_point_deinit(data->my_element, 1); 152 crypto_ec_point_deinit(data->peer_element, 1); 153 bin_clear_free(data->id_peer, data->id_peer_len); 154 bin_clear_free(data->id_server, data->id_server_len); 155 bin_clear_free(data->password, data->password_len); 156 bin_clear_free(data->salt, data->salt_len); 157 if (data->grp) { 158 crypto_ec_deinit(data->grp->group); 159 crypto_ec_point_deinit(data->grp->pwe, 1); 160 os_free(data->grp); 161 } 162 wpabuf_free(data->inbuf); 163 wpabuf_free(data->outbuf); 164 bin_clear_free(data, sizeof(*data)); 165 } 166 167 168 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, 169 u8 id) 170 { 171 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); 172 /* 173 * if we're fragmenting then we already have an id request, just return 174 */ 175 if (data->out_frag_pos) 176 return; 177 178 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + 179 data->id_server_len); 180 if (data->outbuf == NULL) { 181 eap_pwd_state(data, FAILURE); 182 return; 183 } 184 185 if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) { 186 wpabuf_free(data->outbuf); 187 data->outbuf = NULL; 188 eap_pwd_state(data, FAILURE); 189 return; 190 } 191 192 wpa_hexdump_key(MSG_DEBUG, "EAP-pwd (server): password", 193 data->password, data->password_len); 194 if (data->salt_len) 195 wpa_hexdump(MSG_DEBUG, "EAP-pwd (server): salt", 196 data->salt, data->salt_len); 197 198 /* 199 * If this is a salted password then figure out how it was hashed 200 * based on the length. 201 */ 202 if (data->salt_len) { 203 switch (data->password_len) { 204 case 20: 205 data->password_prep = EAP_PWD_PREP_SSHA1; 206 break; 207 case 32: 208 data->password_prep = EAP_PWD_PREP_SSHA256; 209 break; 210 case 64: 211 data->password_prep = EAP_PWD_PREP_SSHA512; 212 break; 213 default: 214 wpa_printf(MSG_INFO, 215 "EAP-pwd (server): bad size %d for salted password", 216 (int) data->password_len); 217 eap_pwd_state(data, FAILURE); 218 return; 219 } 220 } else { 221 /* Otherwise, figure out whether it's MS hashed or plain */ 222 data->password_prep = data->password_hash ? EAP_PWD_PREP_MS : 223 EAP_PWD_PREP_NONE; 224 } 225 226 wpabuf_put_be16(data->outbuf, data->group_num); 227 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 228 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 229 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); 230 wpabuf_put_u8(data->outbuf, data->password_prep); 231 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); 232 } 233 234 235 static void eap_pwd_build_commit_req(struct eap_sm *sm, 236 struct eap_pwd_data *data, u8 id) 237 { 238 struct crypto_bignum *mask = NULL; 239 u8 *scalar = NULL, *element = NULL; 240 size_t prime_len, order_len; 241 242 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 243 /* 244 * if we're fragmenting then we already have an commit request, just 245 * return 246 */ 247 if (data->out_frag_pos) 248 return; 249 250 prime_len = crypto_ec_prime_len(data->grp->group); 251 order_len = crypto_ec_order_len(data->grp->group); 252 253 data->private_value = crypto_bignum_init(); 254 data->my_element = crypto_ec_point_init(data->grp->group); 255 data->my_scalar = crypto_bignum_init(); 256 mask = crypto_bignum_init(); 257 if (!data->private_value || !data->my_element || !data->my_scalar || 258 !mask) { 259 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 260 "fail"); 261 goto fin; 262 } 263 264 if (crypto_bignum_rand(data->private_value, 265 crypto_ec_get_order(data->grp->group)) < 0 || 266 crypto_bignum_rand(mask, 267 crypto_ec_get_order(data->grp->group)) < 0 || 268 crypto_bignum_add(data->private_value, mask, data->my_scalar) < 0 || 269 crypto_bignum_mod(data->my_scalar, 270 crypto_ec_get_order(data->grp->group), 271 data->my_scalar) < 0) { 272 wpa_printf(MSG_INFO, 273 "EAP-pwd (server): unable to get randomness"); 274 goto fin; 275 } 276 277 if (crypto_ec_point_mul(data->grp->group, data->grp->pwe, mask, 278 data->my_element) < 0) { 279 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 280 "fail"); 281 eap_pwd_state(data, FAILURE); 282 goto fin; 283 } 284 285 if (crypto_ec_point_invert(data->grp->group, data->my_element) < 0) { 286 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 287 "fail"); 288 goto fin; 289 } 290 291 scalar = os_malloc(order_len); 292 element = os_malloc(prime_len * 2); 293 if (!scalar || !element) { 294 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 295 goto fin; 296 } 297 298 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, element, 299 element + prime_len) < 0) { 300 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 301 "fail"); 302 goto fin; 303 } 304 305 crypto_bignum_to_bin(data->my_scalar, scalar, order_len, order_len); 306 307 data->outbuf = wpabuf_alloc(2 * prime_len + order_len + 308 (data->salt ? 1 + data->salt_len : 0)); 309 if (data->outbuf == NULL) 310 goto fin; 311 312 /* If we're doing salted password prep, add the salt */ 313 if (data->salt_len) { 314 wpabuf_put_u8(data->outbuf, data->salt_len); 315 wpabuf_put_data(data->outbuf, data->salt, data->salt_len); 316 } 317 318 /* We send the element as (x,y) followed by the scalar */ 319 wpabuf_put_data(data->outbuf, element, 2 * prime_len); 320 wpabuf_put_data(data->outbuf, scalar, order_len); 321 322 fin: 323 crypto_bignum_deinit(mask, 1); 324 os_free(scalar); 325 os_free(element); 326 if (data->outbuf == NULL) 327 eap_pwd_state(data, FAILURE); 328 } 329 330 331 static void eap_pwd_build_confirm_req(struct eap_sm *sm, 332 struct eap_pwd_data *data, u8 id) 333 { 334 struct crypto_hash *hash; 335 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 336 u16 grp; 337 size_t prime_len, order_len; 338 339 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 340 /* 341 * if we're fragmenting then we already have an confirm request, just 342 * return 343 */ 344 if (data->out_frag_pos) 345 return; 346 347 prime_len = crypto_ec_prime_len(data->grp->group); 348 order_len = crypto_ec_order_len(data->grp->group); 349 350 /* Each component of the cruft will be at most as big as the prime */ 351 cruft = os_malloc(prime_len * 2); 352 if (!cruft) { 353 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 354 "fail"); 355 goto fin; 356 } 357 358 /* 359 * commit is H(k | server_element | server_scalar | peer_element | 360 * peer_scalar | ciphersuite) 361 */ 362 hash = eap_pwd_h_init(); 363 if (hash == NULL) 364 goto fin; 365 366 /* 367 * Zero the memory each time because this is mod prime math and some 368 * value may start with a few zeros and the previous one did not. 369 * 370 * First is k 371 */ 372 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len); 373 eap_pwd_h_update(hash, cruft, prime_len); 374 375 /* server element: x, y */ 376 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft, 377 cruft + prime_len) < 0) { 378 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 379 "assignment fail"); 380 goto fin; 381 } 382 eap_pwd_h_update(hash, cruft, prime_len * 2); 383 384 /* server scalar */ 385 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len); 386 eap_pwd_h_update(hash, cruft, order_len); 387 388 /* peer element: x, y */ 389 if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft, 390 cruft + prime_len) < 0) { 391 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 392 "assignment fail"); 393 goto fin; 394 } 395 eap_pwd_h_update(hash, cruft, prime_len * 2); 396 397 /* peer scalar */ 398 crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len); 399 eap_pwd_h_update(hash, cruft, order_len); 400 401 /* ciphersuite */ 402 grp = htons(data->group_num); 403 os_memset(cruft, 0, prime_len); 404 ptr = cruft; 405 os_memcpy(ptr, &grp, sizeof(u16)); 406 ptr += sizeof(u16); 407 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 408 ptr += sizeof(u8); 409 *ptr = EAP_PWD_DEFAULT_PRF; 410 ptr += sizeof(u8); 411 eap_pwd_h_update(hash, cruft, ptr - cruft); 412 413 /* all done with the random function */ 414 eap_pwd_h_final(hash, conf); 415 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 416 417 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 418 if (data->outbuf == NULL) 419 goto fin; 420 421 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 422 423 fin: 424 bin_clear_free(cruft, prime_len * 2); 425 if (data->outbuf == NULL) 426 eap_pwd_state(data, FAILURE); 427 } 428 429 430 static struct wpabuf * 431 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 432 { 433 struct eap_pwd_data *data = priv; 434 struct wpabuf *req; 435 u8 lm_exch; 436 const u8 *buf; 437 u16 totlen = 0; 438 size_t len; 439 440 /* 441 * if we're buffering response fragments then just ACK 442 */ 443 if (data->in_frag_pos) { 444 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); 445 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 446 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); 447 if (req == NULL) { 448 eap_pwd_state(data, FAILURE); 449 return NULL; 450 } 451 switch (data->state) { 452 case PWD_ID_Req: 453 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 454 break; 455 case PWD_Commit_Req: 456 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 457 break; 458 case PWD_Confirm_Req: 459 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 460 break; 461 default: 462 eap_pwd_state(data, FAILURE); /* just to be sure */ 463 wpabuf_free(req); 464 return NULL; 465 } 466 return req; 467 } 468 469 /* 470 * build the data portion of a request 471 */ 472 switch (data->state) { 473 case PWD_ID_Req: 474 eap_pwd_build_id_req(sm, data, id); 475 lm_exch = EAP_PWD_OPCODE_ID_EXCH; 476 break; 477 case PWD_Commit_Req: 478 eap_pwd_build_commit_req(sm, data, id); 479 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; 480 break; 481 case PWD_Confirm_Req: 482 eap_pwd_build_confirm_req(sm, data, id); 483 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; 484 break; 485 default: 486 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 487 data->state); 488 eap_pwd_state(data, FAILURE); 489 lm_exch = 0; /* hush now, sweet compiler */ 490 break; 491 } 492 493 if (data->state == FAILURE) 494 return NULL; 495 496 /* 497 * determine whether that data needs to be fragmented 498 */ 499 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 500 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 501 len = data->mtu - EAP_PWD_HDR_SIZE; 502 EAP_PWD_SET_MORE_BIT(lm_exch); 503 /* 504 * if this is the first fragment, need to set the M bit 505 * and add the total length to the eap_pwd_hdr 506 */ 507 if (data->out_frag_pos == 0) { 508 EAP_PWD_SET_LENGTH_BIT(lm_exch); 509 totlen = wpabuf_len(data->outbuf) + 510 EAP_PWD_HDR_SIZE + sizeof(u16); 511 len -= sizeof(u16); 512 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " 513 "total length = %d", totlen); 514 } 515 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", 516 (int) len); 517 } 518 519 /* 520 * alloc an eap request and populate it with the data 521 */ 522 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 523 EAP_PWD_HDR_SIZE + len + 524 (totlen ? sizeof(u16) : 0), 525 EAP_CODE_REQUEST, id); 526 if (req == NULL) { 527 eap_pwd_state(data, FAILURE); 528 return NULL; 529 } 530 531 wpabuf_put_u8(req, lm_exch); 532 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) 533 wpabuf_put_be16(req, totlen); 534 535 buf = wpabuf_head_u8(data->outbuf); 536 wpabuf_put_data(req, buf + data->out_frag_pos, len); 537 data->out_frag_pos += len; 538 /* 539 * either not fragged or last fragment, either way free up the data 540 */ 541 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 542 wpabuf_free(data->outbuf); 543 data->outbuf = NULL; 544 data->out_frag_pos = 0; 545 } 546 547 return req; 548 } 549 550 551 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 552 struct wpabuf *respData) 553 { 554 struct eap_pwd_data *data = priv; 555 const u8 *pos; 556 size_t len; 557 558 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 559 if (pos == NULL || len < 1) { 560 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 561 return TRUE; 562 } 563 564 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", 565 EAP_PWD_GET_EXCHANGE(*pos), (int) len); 566 567 if (data->state == PWD_ID_Req && 568 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) 569 return FALSE; 570 571 if (data->state == PWD_Commit_Req && 572 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) 573 return FALSE; 574 575 if (data->state == PWD_Confirm_Req && 576 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) 577 return FALSE; 578 579 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 580 *pos, data->state); 581 582 return TRUE; 583 } 584 585 586 static void eap_pwd_process_id_resp(struct eap_sm *sm, 587 struct eap_pwd_data *data, 588 const u8 *payload, size_t payload_len) 589 { 590 struct eap_pwd_id *id; 591 const u8 *password; 592 size_t password_len; 593 u8 pwhashhash[16]; 594 int res; 595 596 if (payload_len < sizeof(struct eap_pwd_id)) { 597 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 598 return; 599 } 600 601 id = (struct eap_pwd_id *) payload; 602 if ((data->group_num != be_to_host16(id->group_num)) || 603 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 604 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 605 (id->prf != EAP_PWD_DEFAULT_PRF) || 606 (id->prep != data->password_prep)) { 607 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 608 eap_pwd_state(data, FAILURE); 609 return; 610 } 611 if (data->id_peer || data->grp) { 612 wpa_printf(MSG_INFO, "EAP-pwd: data was already allocated"); 613 return; 614 } 615 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 616 if (data->id_peer == NULL) { 617 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 618 return; 619 } 620 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 621 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 622 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 623 data->id_peer, data->id_peer_len); 624 625 data->grp = get_eap_pwd_group(data->group_num); 626 if (data->grp == NULL) { 627 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 628 "group"); 629 return; 630 } 631 632 /* 633 * If it's PREP_MS then hash the password again, otherwise regardless 634 * of the prep the client is doing, the password we have is the one to 635 * use to generate the password element. 636 */ 637 if (data->password_prep == EAP_PWD_PREP_MS) { 638 res = hash_nt_password_hash(data->password, pwhashhash); 639 if (res) 640 return; 641 password = pwhashhash; 642 password_len = sizeof(pwhashhash); 643 } else { 644 password = data->password; 645 password_len = data->password_len; 646 } 647 648 res = compute_password_element(data->grp, data->group_num, 649 password, password_len, 650 data->id_server, data->id_server_len, 651 data->id_peer, data->id_peer_len, 652 (u8 *) &data->token); 653 os_memset(pwhashhash, 0, sizeof(pwhashhash)); 654 if (res) { 655 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 656 "PWE"); 657 return; 658 } 659 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 660 (int) crypto_ec_prime_len_bits(data->grp->group)); 661 662 eap_pwd_state(data, PWD_Commit_Req); 663 } 664 665 666 static void 667 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 668 const u8 *payload, size_t payload_len) 669 { 670 const u8 *ptr; 671 struct crypto_bignum *cofactor = NULL; 672 struct crypto_ec_point *K = NULL; 673 int res = 0; 674 size_t prime_len, order_len; 675 676 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 677 678 prime_len = crypto_ec_prime_len(data->grp->group); 679 order_len = crypto_ec_order_len(data->grp->group); 680 681 if (payload_len != 2 * prime_len + order_len) { 682 wpa_printf(MSG_INFO, 683 "EAP-pwd: Unexpected Commit payload length %u (expected %u)", 684 (unsigned int) payload_len, 685 (unsigned int) (2 * prime_len + order_len)); 686 goto fin; 687 } 688 689 data->k = crypto_bignum_init(); 690 cofactor = crypto_bignum_init(); 691 K = crypto_ec_point_init(data->grp->group); 692 if (!data->k || !cofactor || !K) { 693 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 694 "fail"); 695 goto fin; 696 } 697 698 if (crypto_ec_cofactor(data->grp->group, cofactor) < 0) { 699 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 700 "cofactor for curve"); 701 goto fin; 702 } 703 704 /* element, x then y, followed by scalar */ 705 ptr = payload; 706 data->peer_element = eap_pwd_get_element(data->grp, ptr); 707 if (!data->peer_element) { 708 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 709 "fail"); 710 goto fin; 711 } 712 ptr += prime_len * 2; 713 data->peer_scalar = eap_pwd_get_scalar(data->grp, ptr); 714 if (!data->peer_scalar) { 715 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 716 "fail"); 717 goto fin; 718 } 719 720 /* detect reflection attacks */ 721 if (crypto_bignum_cmp(data->my_scalar, data->peer_scalar) == 0 || 722 crypto_ec_point_cmp(data->grp->group, data->my_element, 723 data->peer_element) == 0) { 724 wpa_printf(MSG_INFO, 725 "EAP-PWD (server): detected reflection attack!"); 726 goto fin; 727 } 728 729 /* compute the shared key, k */ 730 if ((crypto_ec_point_mul(data->grp->group, data->grp->pwe, 731 data->peer_scalar, K) < 0) || 732 (crypto_ec_point_add(data->grp->group, K, data->peer_element, 733 K) < 0) || 734 (crypto_ec_point_mul(data->grp->group, K, data->private_value, 735 K) < 0)) { 736 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 737 "fail"); 738 goto fin; 739 } 740 741 /* ensure that the shared key isn't in a small sub-group */ 742 if (!crypto_bignum_is_one(cofactor)) { 743 if (crypto_ec_point_mul(data->grp->group, K, cofactor, 744 K) != 0) { 745 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 746 "multiply shared key point by order!\n"); 747 goto fin; 748 } 749 } 750 751 /* 752 * This check is strictly speaking just for the case above where 753 * co-factor > 1 but it was suggested that even though this is probably 754 * never going to happen it is a simple and safe check "just to be 755 * sure" so let's be safe. 756 */ 757 if (crypto_ec_point_is_at_infinity(data->grp->group, K)) { 758 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 759 "at infinity"); 760 goto fin; 761 } 762 if (crypto_ec_point_x(data->grp->group, K, data->k)) { 763 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 764 "shared secret from secret point"); 765 goto fin; 766 } 767 res = 1; 768 769 fin: 770 crypto_ec_point_deinit(K, 1); 771 crypto_bignum_deinit(cofactor, 1); 772 773 if (res) 774 eap_pwd_state(data, PWD_Confirm_Req); 775 else 776 eap_pwd_state(data, FAILURE); 777 } 778 779 780 static void 781 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 782 const u8 *payload, size_t payload_len) 783 { 784 struct crypto_hash *hash; 785 u32 cs; 786 u16 grp; 787 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 788 size_t prime_len, order_len; 789 790 prime_len = crypto_ec_prime_len(data->grp->group); 791 order_len = crypto_ec_order_len(data->grp->group); 792 793 if (payload_len != SHA256_MAC_LEN) { 794 wpa_printf(MSG_INFO, 795 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)", 796 (unsigned int) payload_len, SHA256_MAC_LEN); 797 goto fin; 798 } 799 800 /* build up the ciphersuite: group | random_function | prf */ 801 grp = htons(data->group_num); 802 ptr = (u8 *) &cs; 803 os_memcpy(ptr, &grp, sizeof(u16)); 804 ptr += sizeof(u16); 805 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 806 ptr += sizeof(u8); 807 *ptr = EAP_PWD_DEFAULT_PRF; 808 809 /* each component of the cruft will be at most as big as the prime */ 810 cruft = os_malloc(prime_len * 2); 811 if (!cruft) { 812 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 813 goto fin; 814 } 815 816 /* 817 * commit is H(k | peer_element | peer_scalar | server_element | 818 * server_scalar | ciphersuite) 819 */ 820 hash = eap_pwd_h_init(); 821 if (hash == NULL) 822 goto fin; 823 824 /* k */ 825 crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len); 826 eap_pwd_h_update(hash, cruft, prime_len); 827 828 /* peer element: x, y */ 829 if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft, 830 cruft + prime_len) < 0) { 831 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 832 "assignment fail"); 833 goto fin; 834 } 835 eap_pwd_h_update(hash, cruft, prime_len * 2); 836 837 /* peer scalar */ 838 crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len); 839 eap_pwd_h_update(hash, cruft, order_len); 840 841 /* server element: x, y */ 842 if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft, 843 cruft + prime_len) < 0) { 844 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 845 "assignment fail"); 846 goto fin; 847 } 848 eap_pwd_h_update(hash, cruft, prime_len * 2); 849 850 /* server scalar */ 851 crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len); 852 eap_pwd_h_update(hash, cruft, order_len); 853 854 /* ciphersuite */ 855 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 856 857 /* all done */ 858 eap_pwd_h_final(hash, conf); 859 860 ptr = (u8 *) payload; 861 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 862 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 863 "verify"); 864 goto fin; 865 } 866 867 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 868 if (compute_keys(data->grp, data->k, 869 data->peer_scalar, data->my_scalar, conf, 870 data->my_confirm, &cs, data->msk, data->emsk, 871 data->session_id) < 0) 872 eap_pwd_state(data, FAILURE); 873 else 874 eap_pwd_state(data, SUCCESS); 875 876 fin: 877 bin_clear_free(cruft, prime_len * 2); 878 } 879 880 881 static void eap_pwd_process(struct eap_sm *sm, void *priv, 882 struct wpabuf *respData) 883 { 884 struct eap_pwd_data *data = priv; 885 const u8 *pos; 886 size_t len; 887 u8 lm_exch; 888 u16 tot_len; 889 890 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 891 if ((pos == NULL) || (len < 1)) { 892 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 893 (pos == NULL) ? "is NULL" : "is not NULL", 894 (int) len); 895 return; 896 } 897 898 lm_exch = *pos; 899 pos++; /* skip over the bits and the exch */ 900 len--; 901 902 /* 903 * if we're fragmenting then this should be an ACK with no data, 904 * just return and continue fragmenting in the "build" section above 905 */ 906 if (data->out_frag_pos) { 907 if (len > 1) 908 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 909 "Fragmenting but not an ACK"); 910 else 911 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 912 "peer"); 913 return; 914 } 915 /* 916 * if we're receiving fragmented packets then we need to buffer... 917 * 918 * the first fragment has a total length 919 */ 920 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 921 if (len < 2) { 922 wpa_printf(MSG_DEBUG, 923 "EAP-pwd: Frame too short to contain Total-Length field"); 924 return; 925 } 926 tot_len = WPA_GET_BE16(pos); 927 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 928 "length = %d", tot_len); 929 if (tot_len > 15000) 930 return; 931 if (data->inbuf) { 932 wpa_printf(MSG_DEBUG, 933 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use"); 934 return; 935 } 936 data->inbuf = wpabuf_alloc(tot_len); 937 if (data->inbuf == NULL) { 938 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 939 "buffer fragments!"); 940 return; 941 } 942 data->in_frag_pos = 0; 943 pos += sizeof(u16); 944 len -= sizeof(u16); 945 } 946 /* 947 * the first and all intermediate fragments have the M bit set 948 */ 949 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) { 950 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 951 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 952 "attack detected! (%d+%d > %d)", 953 (int) data->in_frag_pos, (int) len, 954 (int) wpabuf_size(data->inbuf)); 955 eap_pwd_state(data, FAILURE); 956 return; 957 } 958 wpabuf_put_data(data->inbuf, pos, len); 959 data->in_frag_pos += len; 960 } 961 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 962 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 963 (int) len); 964 return; 965 } 966 /* 967 * last fragment won't have the M bit set (but we're obviously 968 * buffering fragments so that's how we know it's the last) 969 */ 970 if (data->in_frag_pos) { 971 pos = wpabuf_head_u8(data->inbuf); 972 len = data->in_frag_pos; 973 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 974 (int) len); 975 } 976 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 977 case EAP_PWD_OPCODE_ID_EXCH: 978 eap_pwd_process_id_resp(sm, data, pos, len); 979 break; 980 case EAP_PWD_OPCODE_COMMIT_EXCH: 981 eap_pwd_process_commit_resp(sm, data, pos, len); 982 break; 983 case EAP_PWD_OPCODE_CONFIRM_EXCH: 984 eap_pwd_process_confirm_resp(sm, data, pos, len); 985 break; 986 } 987 /* 988 * if we had been buffering fragments, here's a great place 989 * to clean up 990 */ 991 if (data->in_frag_pos) { 992 wpabuf_free(data->inbuf); 993 data->inbuf = NULL; 994 data->in_frag_pos = 0; 995 } 996 } 997 998 999 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 1000 { 1001 struct eap_pwd_data *data = priv; 1002 u8 *key; 1003 1004 if (data->state != SUCCESS) 1005 return NULL; 1006 1007 key = os_memdup(data->msk, EAP_MSK_LEN); 1008 if (key == NULL) 1009 return NULL; 1010 1011 *len = EAP_MSK_LEN; 1012 1013 return key; 1014 } 1015 1016 1017 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 1018 { 1019 struct eap_pwd_data *data = priv; 1020 u8 *key; 1021 1022 if (data->state != SUCCESS) 1023 return NULL; 1024 1025 key = os_memdup(data->emsk, EAP_EMSK_LEN); 1026 if (key == NULL) 1027 return NULL; 1028 1029 *len = EAP_EMSK_LEN; 1030 1031 return key; 1032 } 1033 1034 1035 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1036 { 1037 struct eap_pwd_data *data = priv; 1038 return data->state == SUCCESS; 1039 } 1040 1041 1042 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1043 { 1044 struct eap_pwd_data *data = priv; 1045 return (data->state == SUCCESS) || (data->state == FAILURE); 1046 } 1047 1048 1049 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 1050 { 1051 struct eap_pwd_data *data = priv; 1052 u8 *id; 1053 1054 if (data->state != SUCCESS) 1055 return NULL; 1056 1057 id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN); 1058 if (id == NULL) 1059 return NULL; 1060 1061 *len = 1 + SHA256_MAC_LEN; 1062 1063 return id; 1064 } 1065 1066 1067 int eap_server_pwd_register(void) 1068 { 1069 struct eap_method *eap; 1070 struct timeval tp; 1071 struct timezone tz; 1072 u32 sr; 1073 1074 sr = 0xdeaddada; 1075 (void) gettimeofday(&tp, &tz); 1076 sr ^= (tp.tv_sec ^ tp.tv_usec); 1077 srandom(sr); 1078 1079 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1080 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1081 "PWD"); 1082 if (eap == NULL) 1083 return -1; 1084 1085 eap->init = eap_pwd_init; 1086 eap->reset = eap_pwd_reset; 1087 eap->buildReq = eap_pwd_build_req; 1088 eap->check = eap_pwd_check; 1089 eap->process = eap_pwd_process; 1090 eap->isDone = eap_pwd_is_done; 1091 eap->getKey = eap_pwd_getkey; 1092 eap->get_emsk = eap_pwd_get_emsk; 1093 eap->isSuccess = eap_pwd_is_success; 1094 eap->getSessionId = eap_pwd_get_session_id; 1095 1096 return eap_server_method_register(eap); 1097 } 1098