1 /* 2 * EAP peer method: EAP-pwd (RFC 5931) 3 * Copyright (c) 2010, Dan Harkins <dharkins (at) 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 "eap_peer/eap_i.h" 14 #include "eap_common/eap_pwd_common.h" 15 16 17 struct eap_pwd_data { 18 enum { 19 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, 20 SUCCESS_ON_FRAG_COMPLETION, SUCCESS, FAILURE 21 } state; 22 u8 *id_peer; 23 size_t id_peer_len; 24 u8 *id_server; 25 size_t id_server_len; 26 u8 *password; 27 size_t password_len; 28 u16 group_num; 29 EAP_PWD_group *grp; 30 31 struct wpabuf *inbuf; 32 size_t in_frag_pos; 33 struct wpabuf *outbuf; 34 size_t out_frag_pos; 35 size_t mtu; 36 37 BIGNUM *k; 38 BIGNUM *private_value; 39 BIGNUM *server_scalar; 40 BIGNUM *my_scalar; 41 EC_POINT *my_element; 42 EC_POINT *server_element; 43 44 u8 msk[EAP_MSK_LEN]; 45 u8 emsk[EAP_EMSK_LEN]; 46 u8 session_id[1 + SHA256_MAC_LEN]; 47 48 BN_CTX *bnctx; 49 }; 50 51 52 #ifndef CONFIG_NO_STDOUT_DEBUG 53 static const char * eap_pwd_state_txt(int state) 54 { 55 switch (state) { 56 case PWD_ID_Req: 57 return "PWD-ID-Req"; 58 case PWD_Commit_Req: 59 return "PWD-Commit-Req"; 60 case PWD_Confirm_Req: 61 return "PWD-Confirm-Req"; 62 case SUCCESS_ON_FRAG_COMPLETION: 63 return "SUCCESS_ON_FRAG_COMPLETION"; 64 case SUCCESS: 65 return "SUCCESS"; 66 case FAILURE: 67 return "FAILURE"; 68 default: 69 return "PWD-UNK"; 70 } 71 } 72 #endif /* CONFIG_NO_STDOUT_DEBUG */ 73 74 75 static void eap_pwd_state(struct eap_pwd_data *data, int state) 76 { 77 wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s", 78 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); 79 data->state = state; 80 } 81 82 83 static void * eap_pwd_init(struct eap_sm *sm) 84 { 85 struct eap_pwd_data *data; 86 const u8 *identity, *password; 87 size_t identity_len, password_len; 88 int fragment_size; 89 90 password = eap_get_config_password(sm, &password_len); 91 if (password == NULL) { 92 wpa_printf(MSG_INFO, "EAP-PWD: No password configured!"); 93 return NULL; 94 } 95 96 identity = eap_get_config_identity(sm, &identity_len); 97 if (identity == NULL) { 98 wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!"); 99 return NULL; 100 } 101 102 if ((data = os_zalloc(sizeof(*data))) == NULL) { 103 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail"); 104 return NULL; 105 } 106 107 if ((data->bnctx = BN_CTX_new()) == NULL) { 108 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); 109 os_free(data); 110 return NULL; 111 } 112 113 if ((data->id_peer = os_malloc(identity_len)) == NULL) { 114 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 115 BN_CTX_free(data->bnctx); 116 os_free(data); 117 return NULL; 118 } 119 120 os_memcpy(data->id_peer, identity, identity_len); 121 data->id_peer_len = identity_len; 122 123 if ((data->password = os_malloc(password_len)) == NULL) { 124 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail"); 125 BN_CTX_free(data->bnctx); 126 bin_clear_free(data->id_peer, data->id_peer_len); 127 os_free(data); 128 return NULL; 129 } 130 os_memcpy(data->password, password, password_len); 131 data->password_len = password_len; 132 133 data->out_frag_pos = data->in_frag_pos = 0; 134 data->inbuf = data->outbuf = NULL; 135 fragment_size = eap_get_config_fragment_size(sm); 136 if (fragment_size <= 0) 137 data->mtu = 1020; /* default from RFC 5931 */ 138 else 139 data->mtu = fragment_size; 140 141 data->state = PWD_ID_Req; 142 143 return data; 144 } 145 146 147 static void eap_pwd_deinit(struct eap_sm *sm, void *priv) 148 { 149 struct eap_pwd_data *data = priv; 150 151 BN_clear_free(data->private_value); 152 BN_clear_free(data->server_scalar); 153 BN_clear_free(data->my_scalar); 154 BN_clear_free(data->k); 155 BN_CTX_free(data->bnctx); 156 EC_POINT_clear_free(data->my_element); 157 EC_POINT_clear_free(data->server_element); 158 bin_clear_free(data->id_peer, data->id_peer_len); 159 bin_clear_free(data->id_server, data->id_server_len); 160 bin_clear_free(data->password, data->password_len); 161 if (data->grp) { 162 EC_GROUP_free(data->grp->group); 163 EC_POINT_clear_free(data->grp->pwe); 164 BN_clear_free(data->grp->order); 165 BN_clear_free(data->grp->prime); 166 os_free(data->grp); 167 } 168 wpabuf_free(data->inbuf); 169 wpabuf_free(data->outbuf); 170 bin_clear_free(data, sizeof(*data)); 171 } 172 173 174 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 175 { 176 struct eap_pwd_data *data = priv; 177 u8 *key; 178 179 if (data->state != SUCCESS) 180 return NULL; 181 182 key = os_malloc(EAP_MSK_LEN); 183 if (key == NULL) 184 return NULL; 185 186 os_memcpy(key, data->msk, EAP_MSK_LEN); 187 *len = EAP_MSK_LEN; 188 189 return key; 190 } 191 192 193 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 194 { 195 struct eap_pwd_data *data = priv; 196 u8 *id; 197 198 if (data->state != SUCCESS) 199 return NULL; 200 201 id = os_malloc(1 + SHA256_MAC_LEN); 202 if (id == NULL) 203 return NULL; 204 205 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN); 206 *len = 1 + SHA256_MAC_LEN; 207 208 return id; 209 } 210 211 212 static void 213 eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data, 214 struct eap_method_ret *ret, 215 const struct wpabuf *reqData, 216 const u8 *payload, size_t payload_len) 217 { 218 struct eap_pwd_id *id; 219 220 if (data->state != PWD_ID_Req) { 221 ret->ignore = TRUE; 222 eap_pwd_state(data, FAILURE); 223 return; 224 } 225 226 if (payload_len < sizeof(struct eap_pwd_id)) { 227 ret->ignore = TRUE; 228 eap_pwd_state(data, FAILURE); 229 return; 230 } 231 232 id = (struct eap_pwd_id *) payload; 233 data->group_num = be_to_host16(id->group_num); 234 if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 235 (id->prf != EAP_PWD_DEFAULT_PRF)) { 236 ret->ignore = TRUE; 237 eap_pwd_state(data, FAILURE); 238 return; 239 } 240 241 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d", 242 data->group_num); 243 244 data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 245 if (data->id_server == NULL) { 246 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 247 eap_pwd_state(data, FAILURE); 248 return; 249 } 250 data->id_server_len = payload_len - sizeof(struct eap_pwd_id); 251 os_memcpy(data->id_server, id->identity, data->id_server_len); 252 wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of", 253 data->id_server, data->id_server_len); 254 255 data->grp = os_zalloc(sizeof(EAP_PWD_group)); 256 if (data->grp == NULL) { 257 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 258 "group"); 259 eap_pwd_state(data, FAILURE); 260 return; 261 } 262 263 /* compute PWE */ 264 if (compute_password_element(data->grp, data->group_num, 265 data->password, data->password_len, 266 data->id_server, data->id_server_len, 267 data->id_peer, data->id_peer_len, 268 id->token)) { 269 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE"); 270 eap_pwd_state(data, FAILURE); 271 return; 272 } 273 274 wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...", 275 BN_num_bits(data->grp->prime)); 276 277 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + 278 data->id_peer_len); 279 if (data->outbuf == NULL) { 280 eap_pwd_state(data, FAILURE); 281 return; 282 } 283 wpabuf_put_be16(data->outbuf, data->group_num); 284 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 285 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 286 wpabuf_put_data(data->outbuf, id->token, sizeof(id->token)); 287 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE); 288 wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len); 289 290 eap_pwd_state(data, PWD_Commit_Req); 291 } 292 293 294 static void 295 eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data, 296 struct eap_method_ret *ret, 297 const struct wpabuf *reqData, 298 const u8 *payload, size_t payload_len) 299 { 300 EC_POINT *K = NULL, *point = NULL; 301 BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL; 302 u16 offset; 303 u8 *ptr, *scalar = NULL, *element = NULL; 304 305 if (((data->private_value = BN_new()) == NULL) || 306 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 307 ((cofactor = BN_new()) == NULL) || 308 ((data->my_scalar = BN_new()) == NULL) || 309 ((mask = BN_new()) == NULL)) { 310 wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail"); 311 goto fin; 312 } 313 314 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 315 wpa_printf(MSG_INFO, "EAP-pwd (peer): unable to get cofactor " 316 "for curve"); 317 goto fin; 318 } 319 320 if (BN_rand_range(data->private_value, data->grp->order) != 1 || 321 BN_rand_range(mask, data->grp->order) != 1 || 322 BN_add(data->my_scalar, data->private_value, mask) != 1 || 323 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 324 data->bnctx) != 1) { 325 wpa_printf(MSG_INFO, 326 "EAP-pwd (peer): unable to get randomness"); 327 goto fin; 328 } 329 330 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 331 data->grp->pwe, mask, data->bnctx)) { 332 wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation " 333 "fail"); 334 eap_pwd_state(data, FAILURE); 335 goto fin; 336 } 337 338 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 339 { 340 wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail"); 341 goto fin; 342 } 343 BN_clear_free(mask); 344 345 if (((x = BN_new()) == NULL) || 346 ((y = BN_new()) == NULL)) { 347 wpa_printf(MSG_INFO, "EAP-PWD (peer): point allocation fail"); 348 goto fin; 349 } 350 351 /* process the request */ 352 if (((data->server_scalar = BN_new()) == NULL) || 353 ((data->k = BN_new()) == NULL) || 354 ((K = EC_POINT_new(data->grp->group)) == NULL) || 355 ((point = EC_POINT_new(data->grp->group)) == NULL) || 356 ((data->server_element = EC_POINT_new(data->grp->group)) == NULL)) 357 { 358 wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation " 359 "fail"); 360 goto fin; 361 } 362 363 /* element, x then y, followed by scalar */ 364 ptr = (u8 *) payload; 365 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 366 ptr += BN_num_bytes(data->grp->prime); 367 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 368 ptr += BN_num_bytes(data->grp->prime); 369 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->server_scalar); 370 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 371 data->server_element, x, y, 372 data->bnctx)) { 373 wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element " 374 "fail"); 375 goto fin; 376 } 377 378 /* check to ensure server's element is not in a small sub-group */ 379 if (BN_cmp(cofactor, BN_value_one())) { 380 if (!EC_POINT_mul(data->grp->group, point, NULL, 381 data->server_element, cofactor, NULL)) { 382 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply " 383 "server element by order!\n"); 384 goto fin; 385 } 386 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 387 wpa_printf(MSG_INFO, "EAP-PWD (peer): server element " 388 "is at infinity!\n"); 389 goto fin; 390 } 391 } 392 393 /* compute the shared key, k */ 394 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 395 data->server_scalar, data->bnctx)) || 396 (!EC_POINT_add(data->grp->group, K, K, data->server_element, 397 data->bnctx)) || 398 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 399 data->bnctx))) { 400 wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key " 401 "fail"); 402 goto fin; 403 } 404 405 /* ensure that the shared key isn't in a small sub-group */ 406 if (BN_cmp(cofactor, BN_value_one())) { 407 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 408 NULL)) { 409 wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply " 410 "shared key point by order"); 411 goto fin; 412 } 413 } 414 415 /* 416 * This check is strictly speaking just for the case above where 417 * co-factor > 1 but it was suggested that even though this is probably 418 * never going to happen it is a simple and safe check "just to be 419 * sure" so let's be safe. 420 */ 421 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 422 wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at " 423 "infinity!\n"); 424 goto fin; 425 } 426 427 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 428 NULL, data->bnctx)) { 429 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract " 430 "shared secret from point"); 431 goto fin; 432 } 433 434 /* now do the response */ 435 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 436 data->my_element, x, y, 437 data->bnctx)) { 438 wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail"); 439 goto fin; 440 } 441 442 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 443 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 444 NULL)) { 445 wpa_printf(MSG_INFO, "EAP-PWD (peer): data allocation fail"); 446 goto fin; 447 } 448 449 /* 450 * bignums occupy as little memory as possible so one that is 451 * sufficiently smaller than the prime or order might need pre-pending 452 * with zeros. 453 */ 454 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 455 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 456 offset = BN_num_bytes(data->grp->order) - 457 BN_num_bytes(data->my_scalar); 458 BN_bn2bin(data->my_scalar, scalar + offset); 459 460 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 461 BN_bn2bin(x, element + offset); 462 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 463 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 464 465 data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) + 466 2 * BN_num_bytes(data->grp->prime)); 467 if (data->outbuf == NULL) 468 goto fin; 469 470 /* we send the element as (x,y) follwed by the scalar */ 471 wpabuf_put_data(data->outbuf, element, 472 2 * BN_num_bytes(data->grp->prime)); 473 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 474 475 fin: 476 os_free(scalar); 477 os_free(element); 478 BN_clear_free(x); 479 BN_clear_free(y); 480 BN_clear_free(cofactor); 481 EC_POINT_clear_free(K); 482 EC_POINT_clear_free(point); 483 if (data->outbuf == NULL) 484 eap_pwd_state(data, FAILURE); 485 else 486 eap_pwd_state(data, PWD_Confirm_Req); 487 } 488 489 490 static void 491 eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data, 492 struct eap_method_ret *ret, 493 const struct wpabuf *reqData, 494 const u8 *payload, size_t payload_len) 495 { 496 BIGNUM *x = NULL, *y = NULL; 497 struct crypto_hash *hash; 498 u32 cs; 499 u16 grp; 500 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 501 int offset; 502 503 /* 504 * first build up the ciphersuite which is group | random_function | 505 * prf 506 */ 507 grp = htons(data->group_num); 508 ptr = (u8 *) &cs; 509 os_memcpy(ptr, &grp, sizeof(u16)); 510 ptr += sizeof(u16); 511 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 512 ptr += sizeof(u8); 513 *ptr = EAP_PWD_DEFAULT_PRF; 514 515 /* each component of the cruft will be at most as big as the prime */ 516 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 517 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 518 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation " 519 "fail"); 520 goto fin; 521 } 522 523 /* 524 * server's commit is H(k | server_element | server_scalar | 525 * peer_element | peer_scalar | ciphersuite) 526 */ 527 hash = eap_pwd_h_init(); 528 if (hash == NULL) 529 goto fin; 530 531 /* 532 * zero the memory each time because this is mod prime math and some 533 * value may start with a few zeros and the previous one did not. 534 */ 535 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 536 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 537 BN_bn2bin(data->k, cruft + offset); 538 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 539 540 /* server element: x, y */ 541 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 542 data->server_element, x, y, 543 data->bnctx)) { 544 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 545 "assignment fail"); 546 goto fin; 547 } 548 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 549 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 550 BN_bn2bin(x, cruft + offset); 551 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 552 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 553 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 554 BN_bn2bin(y, cruft + offset); 555 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 556 557 /* server scalar */ 558 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 559 offset = BN_num_bytes(data->grp->order) - 560 BN_num_bytes(data->server_scalar); 561 BN_bn2bin(data->server_scalar, cruft + offset); 562 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 563 564 /* my element: x, y */ 565 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 566 data->my_element, x, y, 567 data->bnctx)) { 568 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 569 "assignment fail"); 570 goto fin; 571 } 572 573 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 574 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 575 BN_bn2bin(x, cruft + offset); 576 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 577 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 578 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 579 BN_bn2bin(y, cruft + offset); 580 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 581 582 /* my scalar */ 583 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 584 offset = BN_num_bytes(data->grp->order) - 585 BN_num_bytes(data->my_scalar); 586 BN_bn2bin(data->my_scalar, cruft + offset); 587 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 588 589 /* the ciphersuite */ 590 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 591 592 /* random function fin */ 593 eap_pwd_h_final(hash, conf); 594 595 ptr = (u8 *) payload; 596 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 597 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify"); 598 goto fin; 599 } 600 601 wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified"); 602 603 /* 604 * compute confirm: 605 * H(k | peer_element | peer_scalar | server_element | server_scalar | 606 * ciphersuite) 607 */ 608 hash = eap_pwd_h_init(); 609 if (hash == NULL) 610 goto fin; 611 612 /* k */ 613 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 614 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 615 BN_bn2bin(data->k, cruft + offset); 616 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 617 618 /* my element */ 619 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 620 data->my_element, x, y, 621 data->bnctx)) { 622 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point " 623 "assignment fail"); 624 goto fin; 625 } 626 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 627 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 628 BN_bn2bin(x, cruft + offset); 629 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 630 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 631 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 632 BN_bn2bin(y, cruft + offset); 633 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 634 635 /* my scalar */ 636 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 637 offset = BN_num_bytes(data->grp->order) - 638 BN_num_bytes(data->my_scalar); 639 BN_bn2bin(data->my_scalar, cruft + offset); 640 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 641 642 /* server element: x, y */ 643 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 644 data->server_element, x, y, 645 data->bnctx)) { 646 wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point " 647 "assignment fail"); 648 goto fin; 649 } 650 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 651 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 652 BN_bn2bin(x, cruft + offset); 653 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 654 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 655 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 656 BN_bn2bin(y, cruft + offset); 657 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 658 659 /* server scalar */ 660 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 661 offset = BN_num_bytes(data->grp->order) - 662 BN_num_bytes(data->server_scalar); 663 BN_bn2bin(data->server_scalar, cruft + offset); 664 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 665 666 /* the ciphersuite */ 667 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 668 669 /* all done */ 670 eap_pwd_h_final(hash, conf); 671 672 if (compute_keys(data->grp, data->bnctx, data->k, 673 data->my_scalar, data->server_scalar, conf, ptr, 674 &cs, data->msk, data->emsk, data->session_id) < 0) { 675 wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | " 676 "EMSK"); 677 goto fin; 678 } 679 680 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 681 if (data->outbuf == NULL) 682 goto fin; 683 684 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 685 686 fin: 687 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 688 BN_clear_free(x); 689 BN_clear_free(y); 690 if (data->outbuf == NULL) { 691 ret->methodState = METHOD_DONE; 692 ret->decision = DECISION_FAIL; 693 eap_pwd_state(data, FAILURE); 694 } else { 695 eap_pwd_state(data, SUCCESS_ON_FRAG_COMPLETION); 696 } 697 } 698 699 700 static struct wpabuf * 701 eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret, 702 const struct wpabuf *reqData) 703 { 704 struct eap_pwd_data *data = priv; 705 struct wpabuf *resp = NULL; 706 const u8 *pos, *buf; 707 size_t len; 708 u16 tot_len = 0; 709 u8 lm_exch; 710 711 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len); 712 if ((pos == NULL) || (len < 1)) { 713 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and " 714 "len is %d", 715 pos == NULL ? "NULL" : "not NULL", (int) len); 716 ret->ignore = TRUE; 717 return NULL; 718 } 719 720 ret->ignore = FALSE; 721 ret->methodState = METHOD_MAY_CONT; 722 ret->decision = DECISION_FAIL; 723 ret->allowNotifications = FALSE; 724 725 lm_exch = *pos; 726 pos++; /* skip over the bits and the exch */ 727 len--; 728 729 /* 730 * we're fragmenting so send out the next fragment 731 */ 732 if (data->out_frag_pos) { 733 /* 734 * this should be an ACK 735 */ 736 if (len) 737 wpa_printf(MSG_INFO, "Bad Response! Fragmenting but " 738 "not an ACK"); 739 740 wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment"); 741 /* 742 * check if there are going to be more fragments 743 */ 744 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 745 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 746 len = data->mtu - EAP_PWD_HDR_SIZE; 747 EAP_PWD_SET_MORE_BIT(lm_exch); 748 } 749 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 750 EAP_PWD_HDR_SIZE + len, 751 EAP_CODE_RESPONSE, eap_get_id(reqData)); 752 if (resp == NULL) { 753 wpa_printf(MSG_INFO, "Unable to allocate memory for " 754 "next fragment!"); 755 return NULL; 756 } 757 wpabuf_put_u8(resp, lm_exch); 758 buf = wpabuf_head_u8(data->outbuf); 759 wpabuf_put_data(resp, buf + data->out_frag_pos, len); 760 data->out_frag_pos += len; 761 /* 762 * this is the last fragment so get rid of the out buffer 763 */ 764 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 765 wpabuf_free(data->outbuf); 766 data->outbuf = NULL; 767 data->out_frag_pos = 0; 768 } 769 wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes", 770 data->out_frag_pos == 0 ? "last" : "next", 771 (int) len); 772 if (data->state == SUCCESS_ON_FRAG_COMPLETION) { 773 ret->methodState = METHOD_DONE; 774 ret->decision = DECISION_UNCOND_SUCC; 775 eap_pwd_state(data, SUCCESS); 776 } 777 return resp; 778 } 779 780 /* 781 * see if this is a fragment that needs buffering 782 * 783 * if it's the first fragment there'll be a length field 784 */ 785 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 786 tot_len = WPA_GET_BE16(pos); 787 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose " 788 "total length = %d", tot_len); 789 if (tot_len > 15000) 790 return NULL; 791 data->inbuf = wpabuf_alloc(tot_len); 792 if (data->inbuf == NULL) { 793 wpa_printf(MSG_INFO, "Out of memory to buffer " 794 "fragments!"); 795 return NULL; 796 } 797 pos += sizeof(u16); 798 len -= sizeof(u16); 799 } 800 /* 801 * buffer and ACK the fragment 802 */ 803 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 804 data->in_frag_pos += len; 805 if (data->in_frag_pos > wpabuf_size(data->inbuf)) { 806 wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack " 807 "detected (%d vs. %d)!", 808 (int) data->in_frag_pos, 809 (int) wpabuf_len(data->inbuf)); 810 wpabuf_free(data->inbuf); 811 data->inbuf = NULL; 812 data->in_frag_pos = 0; 813 return NULL; 814 } 815 wpabuf_put_data(data->inbuf, pos, len); 816 817 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 818 EAP_PWD_HDR_SIZE, 819 EAP_CODE_RESPONSE, eap_get_id(reqData)); 820 if (resp != NULL) 821 wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch))); 822 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment", 823 (int) len); 824 return resp; 825 } 826 /* 827 * we're buffering and this is the last fragment 828 */ 829 if (data->in_frag_pos) { 830 wpabuf_put_data(data->inbuf, pos, len); 831 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 832 (int) len); 833 data->in_frag_pos += len; 834 pos = wpabuf_head_u8(data->inbuf); 835 len = data->in_frag_pos; 836 } 837 wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d", 838 EAP_PWD_GET_EXCHANGE(lm_exch), (int) len); 839 840 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 841 case EAP_PWD_OPCODE_ID_EXCH: 842 eap_pwd_perform_id_exchange(sm, data, ret, reqData, 843 pos, len); 844 break; 845 case EAP_PWD_OPCODE_COMMIT_EXCH: 846 eap_pwd_perform_commit_exchange(sm, data, ret, reqData, 847 pos, len); 848 break; 849 case EAP_PWD_OPCODE_CONFIRM_EXCH: 850 eap_pwd_perform_confirm_exchange(sm, data, ret, reqData, 851 pos, len); 852 break; 853 default: 854 wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown " 855 "opcode %d", lm_exch); 856 break; 857 } 858 /* 859 * if we buffered the just processed input now's the time to free it 860 */ 861 if (data->in_frag_pos) { 862 wpabuf_free(data->inbuf); 863 data->inbuf = NULL; 864 data->in_frag_pos = 0; 865 } 866 867 if (data->outbuf == NULL) { 868 ret->methodState = METHOD_DONE; 869 ret->decision = DECISION_FAIL; 870 return NULL; /* generic failure */ 871 } 872 873 /* 874 * we have output! Do we need to fragment it? 875 */ 876 len = wpabuf_len(data->outbuf); 877 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 878 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu, 879 EAP_CODE_RESPONSE, eap_get_id(reqData)); 880 /* 881 * if so it's the first so include a length field 882 */ 883 EAP_PWD_SET_LENGTH_BIT(lm_exch); 884 EAP_PWD_SET_MORE_BIT(lm_exch); 885 tot_len = len; 886 /* 887 * keep the packet at the MTU 888 */ 889 len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16); 890 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total " 891 "length = %d", tot_len); 892 } else { 893 resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 894 EAP_PWD_HDR_SIZE + len, 895 EAP_CODE_RESPONSE, eap_get_id(reqData)); 896 } 897 if (resp == NULL) 898 return NULL; 899 900 wpabuf_put_u8(resp, lm_exch); 901 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 902 wpabuf_put_be16(resp, tot_len); 903 data->out_frag_pos += len; 904 } 905 buf = wpabuf_head_u8(data->outbuf); 906 wpabuf_put_data(resp, buf, len); 907 /* 908 * if we're not fragmenting then there's no need to carry this around 909 */ 910 if (data->out_frag_pos == 0) { 911 wpabuf_free(data->outbuf); 912 data->outbuf = NULL; 913 data->out_frag_pos = 0; 914 if (data->state == SUCCESS_ON_FRAG_COMPLETION) { 915 ret->methodState = METHOD_DONE; 916 ret->decision = DECISION_UNCOND_SUCC; 917 eap_pwd_state(data, SUCCESS); 918 } 919 } 920 921 return resp; 922 } 923 924 925 static Boolean eap_pwd_key_available(struct eap_sm *sm, void *priv) 926 { 927 struct eap_pwd_data *data = priv; 928 return data->state == SUCCESS; 929 } 930 931 932 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 933 { 934 struct eap_pwd_data *data = priv; 935 u8 *key; 936 937 if (data->state != SUCCESS) 938 return NULL; 939 940 if ((key = os_malloc(EAP_EMSK_LEN)) == NULL) 941 return NULL; 942 943 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 944 *len = EAP_EMSK_LEN; 945 946 return key; 947 } 948 949 950 int eap_peer_pwd_register(void) 951 { 952 struct eap_method *eap; 953 int ret; 954 955 EVP_add_digest(EVP_sha256()); 956 eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION, 957 EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD"); 958 if (eap == NULL) 959 return -1; 960 961 eap->init = eap_pwd_init; 962 eap->deinit = eap_pwd_deinit; 963 eap->process = eap_pwd_process; 964 eap->isKeyAvailable = eap_pwd_key_available; 965 eap->getKey = eap_pwd_getkey; 966 eap->getSessionId = eap_pwd_get_session_id; 967 eap->get_emsk = eap_pwd_get_emsk; 968 969 ret = eap_peer_method_register(eap); 970 if (ret) 971 eap_peer_method_free(eap); 972 return ret; 973 } 974
