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