1 /* 2 * hostapd / EAP-pwd (RFC 5931) server 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 "crypto/ms_funcs.h" 14 #include "eap_server/eap_i.h" 15 #include "eap_common/eap_pwd_common.h" 16 17 18 struct eap_pwd_data { 19 enum { 20 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, 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 int password_hash; 29 u32 token; 30 u16 group_num; 31 EAP_PWD_group *grp; 32 33 struct wpabuf *inbuf; 34 size_t in_frag_pos; 35 struct wpabuf *outbuf; 36 size_t out_frag_pos; 37 size_t mtu; 38 39 BIGNUM *k; 40 BIGNUM *private_value; 41 BIGNUM *peer_scalar; 42 BIGNUM *my_scalar; 43 EC_POINT *my_element; 44 EC_POINT *peer_element; 45 46 u8 my_confirm[SHA256_MAC_LEN]; 47 48 u8 msk[EAP_MSK_LEN]; 49 u8 emsk[EAP_EMSK_LEN]; 50 u8 session_id[1 + SHA256_MAC_LEN]; 51 52 BN_CTX *bnctx; 53 }; 54 55 56 static const char * eap_pwd_state_txt(int state) 57 { 58 switch (state) { 59 case PWD_ID_Req: 60 return "PWD-ID-Req"; 61 case PWD_Commit_Req: 62 return "PWD-Commit-Req"; 63 case PWD_Confirm_Req: 64 return "PWD-Confirm-Req"; 65 case SUCCESS: 66 return "SUCCESS"; 67 case FAILURE: 68 return "FAILURE"; 69 default: 70 return "PWD-Unk"; 71 } 72 } 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 87 if (sm->user == NULL || sm->user->password == NULL || 88 sm->user->password_len == 0) { 89 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " 90 "configured"); 91 return NULL; 92 } 93 94 data = os_zalloc(sizeof(*data)); 95 if (data == NULL) 96 return NULL; 97 98 data->group_num = sm->pwd_group; 99 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", 100 data->group_num); 101 data->state = PWD_ID_Req; 102 103 data->id_server = (u8 *) os_strdup("server"); 104 if (data->id_server) 105 data->id_server_len = os_strlen((char *) data->id_server); 106 107 data->password = os_malloc(sm->user->password_len); 108 if (data->password == NULL) { 109 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " 110 "fail"); 111 bin_clear_free(data->id_server, data->id_server_len); 112 os_free(data); 113 return NULL; 114 } 115 data->password_len = sm->user->password_len; 116 os_memcpy(data->password, sm->user->password, data->password_len); 117 data->password_hash = sm->user->password_hash; 118 119 data->bnctx = BN_CTX_new(); 120 if (data->bnctx == NULL) { 121 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); 122 bin_clear_free(data->password, data->password_len); 123 bin_clear_free(data->id_server, data->id_server_len); 124 os_free(data); 125 return NULL; 126 } 127 128 data->in_frag_pos = data->out_frag_pos = 0; 129 data->inbuf = data->outbuf = NULL; 130 /* use default MTU from RFC 5931 if not configured otherwise */ 131 data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020; 132 133 return data; 134 } 135 136 137 static void eap_pwd_reset(struct eap_sm *sm, void *priv) 138 { 139 struct eap_pwd_data *data = priv; 140 141 BN_clear_free(data->private_value); 142 BN_clear_free(data->peer_scalar); 143 BN_clear_free(data->my_scalar); 144 BN_clear_free(data->k); 145 BN_CTX_free(data->bnctx); 146 EC_POINT_clear_free(data->my_element); 147 EC_POINT_clear_free(data->peer_element); 148 bin_clear_free(data->id_peer, data->id_peer_len); 149 bin_clear_free(data->id_server, data->id_server_len); 150 bin_clear_free(data->password, data->password_len); 151 if (data->grp) { 152 EC_GROUP_free(data->grp->group); 153 EC_POINT_clear_free(data->grp->pwe); 154 BN_clear_free(data->grp->order); 155 BN_clear_free(data->grp->prime); 156 os_free(data->grp); 157 } 158 wpabuf_free(data->inbuf); 159 wpabuf_free(data->outbuf); 160 bin_clear_free(data, sizeof(*data)); 161 } 162 163 164 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, 165 u8 id) 166 { 167 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); 168 /* 169 * if we're fragmenting then we already have an id request, just return 170 */ 171 if (data->out_frag_pos) 172 return; 173 174 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + 175 data->id_server_len); 176 if (data->outbuf == NULL) { 177 eap_pwd_state(data, FAILURE); 178 return; 179 } 180 181 /* an lfsr is good enough to generate unpredictable tokens */ 182 data->token = os_random(); 183 wpabuf_put_be16(data->outbuf, data->group_num); 184 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 185 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 186 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); 187 wpabuf_put_u8(data->outbuf, data->password_hash ? EAP_PWD_PREP_MS : 188 EAP_PWD_PREP_NONE); 189 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); 190 } 191 192 193 static void eap_pwd_build_commit_req(struct eap_sm *sm, 194 struct eap_pwd_data *data, u8 id) 195 { 196 BIGNUM *mask = NULL, *x = NULL, *y = NULL; 197 u8 *scalar = NULL, *element = NULL; 198 u16 offset; 199 200 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 201 /* 202 * if we're fragmenting then we already have an commit request, just 203 * return 204 */ 205 if (data->out_frag_pos) 206 return; 207 208 if (((data->private_value = BN_new()) == NULL) || 209 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 210 ((data->my_scalar = BN_new()) == NULL) || 211 ((mask = BN_new()) == NULL)) { 212 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 213 "fail"); 214 goto fin; 215 } 216 217 if (BN_rand_range(data->private_value, data->grp->order) != 1 || 218 BN_rand_range(mask, data->grp->order) != 1 || 219 BN_add(data->my_scalar, data->private_value, mask) != 1 || 220 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 221 data->bnctx) != 1) { 222 wpa_printf(MSG_INFO, 223 "EAP-pwd (server): unable to get randomness"); 224 goto fin; 225 } 226 227 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 228 data->grp->pwe, mask, data->bnctx)) { 229 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 230 "fail"); 231 eap_pwd_state(data, FAILURE); 232 goto fin; 233 } 234 235 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 236 { 237 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 238 "fail"); 239 goto fin; 240 } 241 BN_clear_free(mask); 242 243 if (((x = BN_new()) == NULL) || 244 ((y = BN_new()) == NULL)) { 245 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 246 "fail"); 247 goto fin; 248 } 249 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 250 data->my_element, x, y, 251 data->bnctx)) { 252 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 253 "fail"); 254 goto fin; 255 } 256 257 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 258 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 259 NULL)) { 260 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 261 goto fin; 262 } 263 264 /* 265 * bignums occupy as little memory as possible so one that is 266 * sufficiently smaller than the prime or order might need pre-pending 267 * with zeros. 268 */ 269 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 270 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 271 offset = BN_num_bytes(data->grp->order) - 272 BN_num_bytes(data->my_scalar); 273 BN_bn2bin(data->my_scalar, scalar + offset); 274 275 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 276 BN_bn2bin(x, element + offset); 277 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 278 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 279 280 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + 281 BN_num_bytes(data->grp->order)); 282 if (data->outbuf == NULL) 283 goto fin; 284 285 /* We send the element as (x,y) followed by the scalar */ 286 wpabuf_put_data(data->outbuf, element, 287 2 * BN_num_bytes(data->grp->prime)); 288 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 289 290 fin: 291 os_free(scalar); 292 os_free(element); 293 BN_clear_free(x); 294 BN_clear_free(y); 295 if (data->outbuf == NULL) 296 eap_pwd_state(data, FAILURE); 297 } 298 299 300 static void eap_pwd_build_confirm_req(struct eap_sm *sm, 301 struct eap_pwd_data *data, u8 id) 302 { 303 BIGNUM *x = NULL, *y = NULL; 304 struct crypto_hash *hash; 305 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 306 u16 grp; 307 int offset; 308 309 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 310 /* 311 * if we're fragmenting then we already have an confirm request, just 312 * return 313 */ 314 if (data->out_frag_pos) 315 return; 316 317 /* Each component of the cruft will be at most as big as the prime */ 318 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 319 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 320 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 321 "fail"); 322 goto fin; 323 } 324 325 /* 326 * commit is H(k | server_element | server_scalar | peer_element | 327 * peer_scalar | ciphersuite) 328 */ 329 hash = eap_pwd_h_init(); 330 if (hash == NULL) 331 goto fin; 332 333 /* 334 * Zero the memory each time because this is mod prime math and some 335 * value may start with a few zeros and the previous one did not. 336 * 337 * First is k 338 */ 339 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 340 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 341 BN_bn2bin(data->k, cruft + offset); 342 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 343 344 /* server element: x, y */ 345 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 346 data->my_element, x, y, 347 data->bnctx)) { 348 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 349 "assignment fail"); 350 goto fin; 351 } 352 353 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 354 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 355 BN_bn2bin(x, cruft + offset); 356 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 357 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 358 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 359 BN_bn2bin(y, cruft + offset); 360 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 361 362 /* server scalar */ 363 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 364 offset = BN_num_bytes(data->grp->order) - 365 BN_num_bytes(data->my_scalar); 366 BN_bn2bin(data->my_scalar, cruft + offset); 367 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 368 369 /* peer element: x, y */ 370 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 371 data->peer_element, x, y, 372 data->bnctx)) { 373 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 374 "assignment fail"); 375 goto fin; 376 } 377 378 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 379 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 380 BN_bn2bin(x, cruft + offset); 381 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 382 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 383 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 384 BN_bn2bin(y, cruft + offset); 385 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 386 387 /* peer scalar */ 388 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 389 offset = BN_num_bytes(data->grp->order) - 390 BN_num_bytes(data->peer_scalar); 391 BN_bn2bin(data->peer_scalar, cruft + offset); 392 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 393 394 /* ciphersuite */ 395 grp = htons(data->group_num); 396 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 397 ptr = cruft; 398 os_memcpy(ptr, &grp, sizeof(u16)); 399 ptr += sizeof(u16); 400 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 401 ptr += sizeof(u8); 402 *ptr = EAP_PWD_DEFAULT_PRF; 403 ptr += sizeof(u8); 404 eap_pwd_h_update(hash, cruft, ptr - cruft); 405 406 /* all done with the random function */ 407 eap_pwd_h_final(hash, conf); 408 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 409 410 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 411 if (data->outbuf == NULL) 412 goto fin; 413 414 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 415 416 fin: 417 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 418 BN_clear_free(x); 419 BN_clear_free(y); 420 if (data->outbuf == NULL) 421 eap_pwd_state(data, FAILURE); 422 } 423 424 425 static struct wpabuf * 426 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 427 { 428 struct eap_pwd_data *data = priv; 429 struct wpabuf *req; 430 u8 lm_exch; 431 const u8 *buf; 432 u16 totlen = 0; 433 size_t len; 434 435 /* 436 * if we're buffering response fragments then just ACK 437 */ 438 if (data->in_frag_pos) { 439 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); 440 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 441 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); 442 if (req == NULL) { 443 eap_pwd_state(data, FAILURE); 444 return NULL; 445 } 446 switch (data->state) { 447 case PWD_ID_Req: 448 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 449 break; 450 case PWD_Commit_Req: 451 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 452 break; 453 case PWD_Confirm_Req: 454 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 455 break; 456 default: 457 eap_pwd_state(data, FAILURE); /* just to be sure */ 458 wpabuf_free(req); 459 return NULL; 460 } 461 return req; 462 } 463 464 /* 465 * build the data portion of a request 466 */ 467 switch (data->state) { 468 case PWD_ID_Req: 469 eap_pwd_build_id_req(sm, data, id); 470 lm_exch = EAP_PWD_OPCODE_ID_EXCH; 471 break; 472 case PWD_Commit_Req: 473 eap_pwd_build_commit_req(sm, data, id); 474 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; 475 break; 476 case PWD_Confirm_Req: 477 eap_pwd_build_confirm_req(sm, data, id); 478 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; 479 break; 480 default: 481 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 482 data->state); 483 eap_pwd_state(data, FAILURE); 484 lm_exch = 0; /* hush now, sweet compiler */ 485 break; 486 } 487 488 if (data->state == FAILURE) 489 return NULL; 490 491 /* 492 * determine whether that data needs to be fragmented 493 */ 494 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 495 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 496 len = data->mtu - EAP_PWD_HDR_SIZE; 497 EAP_PWD_SET_MORE_BIT(lm_exch); 498 /* 499 * if this is the first fragment, need to set the M bit 500 * and add the total length to the eap_pwd_hdr 501 */ 502 if (data->out_frag_pos == 0) { 503 EAP_PWD_SET_LENGTH_BIT(lm_exch); 504 totlen = wpabuf_len(data->outbuf) + 505 EAP_PWD_HDR_SIZE + sizeof(u16); 506 len -= sizeof(u16); 507 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " 508 "total length = %d", totlen); 509 } 510 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", 511 (int) len); 512 } 513 514 /* 515 * alloc an eap request and populate it with the data 516 */ 517 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 518 EAP_PWD_HDR_SIZE + len + 519 (totlen ? sizeof(u16) : 0), 520 EAP_CODE_REQUEST, id); 521 if (req == NULL) { 522 eap_pwd_state(data, FAILURE); 523 return NULL; 524 } 525 526 wpabuf_put_u8(req, lm_exch); 527 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) 528 wpabuf_put_be16(req, totlen); 529 530 buf = wpabuf_head_u8(data->outbuf); 531 wpabuf_put_data(req, buf + data->out_frag_pos, len); 532 data->out_frag_pos += len; 533 /* 534 * either not fragged or last fragment, either way free up the data 535 */ 536 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 537 wpabuf_free(data->outbuf); 538 data->outbuf = NULL; 539 data->out_frag_pos = 0; 540 } 541 542 return req; 543 } 544 545 546 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 547 struct wpabuf *respData) 548 { 549 struct eap_pwd_data *data = priv; 550 const u8 *pos; 551 size_t len; 552 553 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 554 if (pos == NULL || len < 1) { 555 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 556 return TRUE; 557 } 558 559 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", 560 EAP_PWD_GET_EXCHANGE(*pos), (int) len); 561 562 if (data->state == PWD_ID_Req && 563 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) 564 return FALSE; 565 566 if (data->state == PWD_Commit_Req && 567 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) 568 return FALSE; 569 570 if (data->state == PWD_Confirm_Req && 571 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) 572 return FALSE; 573 574 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 575 *pos, data->state); 576 577 return TRUE; 578 } 579 580 581 static void eap_pwd_process_id_resp(struct eap_sm *sm, 582 struct eap_pwd_data *data, 583 const u8 *payload, size_t payload_len) 584 { 585 struct eap_pwd_id *id; 586 const u8 *password; 587 size_t password_len; 588 u8 pwhashhash[16]; 589 int res; 590 591 if (payload_len < sizeof(struct eap_pwd_id)) { 592 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 593 return; 594 } 595 596 id = (struct eap_pwd_id *) payload; 597 if ((data->group_num != be_to_host16(id->group_num)) || 598 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 599 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 600 (id->prf != EAP_PWD_DEFAULT_PRF)) { 601 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 602 eap_pwd_state(data, FAILURE); 603 return; 604 } 605 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 606 if (data->id_peer == NULL) { 607 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 608 return; 609 } 610 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 611 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 612 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 613 data->id_peer, data->id_peer_len); 614 615 data->grp = os_zalloc(sizeof(EAP_PWD_group)); 616 if (data->grp == NULL) { 617 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 618 "group"); 619 return; 620 } 621 622 if (data->password_hash) { 623 res = hash_nt_password_hash(data->password, pwhashhash); 624 if (res) 625 return; 626 password = pwhashhash; 627 password_len = sizeof(pwhashhash); 628 } else { 629 password = data->password; 630 password_len = data->password_len; 631 } 632 633 res = compute_password_element(data->grp, data->group_num, 634 password, password_len, 635 data->id_server, data->id_server_len, 636 data->id_peer, data->id_peer_len, 637 (u8 *) &data->token); 638 os_memset(pwhashhash, 0, sizeof(pwhashhash)); 639 if (res) { 640 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 641 "PWE"); 642 return; 643 } 644 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 645 BN_num_bits(data->grp->prime)); 646 647 eap_pwd_state(data, PWD_Commit_Req); 648 } 649 650 651 static void 652 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 653 const u8 *payload, size_t payload_len) 654 { 655 u8 *ptr; 656 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 657 EC_POINT *K = NULL, *point = NULL; 658 int res = 0; 659 size_t prime_len, order_len; 660 661 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 662 663 prime_len = BN_num_bytes(data->grp->prime); 664 order_len = BN_num_bytes(data->grp->order); 665 666 if (payload_len != 2 * prime_len + order_len) { 667 wpa_printf(MSG_INFO, 668 "EAP-pwd: Unexpected Commit payload length %u (expected %u)", 669 (unsigned int) payload_len, 670 (unsigned int) (2 * prime_len + order_len)); 671 goto fin; 672 } 673 674 if (((data->peer_scalar = BN_new()) == NULL) || 675 ((data->k = BN_new()) == NULL) || 676 ((cofactor = BN_new()) == NULL) || 677 ((x = BN_new()) == NULL) || 678 ((y = BN_new()) == NULL) || 679 ((point = EC_POINT_new(data->grp->group)) == NULL) || 680 ((K = EC_POINT_new(data->grp->group)) == NULL) || 681 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 682 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 683 "fail"); 684 goto fin; 685 } 686 687 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 688 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 689 "cofactor for curve"); 690 goto fin; 691 } 692 693 /* element, x then y, followed by scalar */ 694 ptr = (u8 *) payload; 695 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 696 ptr += BN_num_bytes(data->grp->prime); 697 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 698 ptr += BN_num_bytes(data->grp->prime); 699 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 700 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 701 data->peer_element, x, y, 702 data->bnctx)) { 703 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 704 "fail"); 705 goto fin; 706 } 707 708 /* check to ensure peer's element is not in a small sub-group */ 709 if (BN_cmp(cofactor, BN_value_one())) { 710 if (!EC_POINT_mul(data->grp->group, point, NULL, 711 data->peer_element, cofactor, NULL)) { 712 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 713 "multiply peer element by order"); 714 goto fin; 715 } 716 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 717 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 718 "is at infinity!\n"); 719 goto fin; 720 } 721 } 722 723 /* compute the shared key, k */ 724 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 725 data->peer_scalar, data->bnctx)) || 726 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 727 data->bnctx)) || 728 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 729 data->bnctx))) { 730 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 731 "fail"); 732 goto fin; 733 } 734 735 /* ensure that the shared key isn't in a small sub-group */ 736 if (BN_cmp(cofactor, BN_value_one())) { 737 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 738 NULL)) { 739 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 740 "multiply shared key point by order!\n"); 741 goto fin; 742 } 743 } 744 745 /* 746 * This check is strictly speaking just for the case above where 747 * co-factor > 1 but it was suggested that even though this is probably 748 * never going to happen it is a simple and safe check "just to be 749 * sure" so let's be safe. 750 */ 751 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 752 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 753 "at infinity"); 754 goto fin; 755 } 756 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 757 NULL, data->bnctx)) { 758 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 759 "shared secret from secret point"); 760 goto fin; 761 } 762 res = 1; 763 764 fin: 765 EC_POINT_clear_free(K); 766 EC_POINT_clear_free(point); 767 BN_clear_free(cofactor); 768 BN_clear_free(x); 769 BN_clear_free(y); 770 771 if (res) 772 eap_pwd_state(data, PWD_Confirm_Req); 773 else 774 eap_pwd_state(data, FAILURE); 775 } 776 777 778 static void 779 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 780 const u8 *payload, size_t payload_len) 781 { 782 BIGNUM *x = NULL, *y = NULL; 783 struct crypto_hash *hash; 784 u32 cs; 785 u16 grp; 786 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 787 int offset; 788 789 if (payload_len != SHA256_MAC_LEN) { 790 wpa_printf(MSG_INFO, 791 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)", 792 (unsigned int) payload_len, SHA256_MAC_LEN); 793 goto fin; 794 } 795 796 /* build up the ciphersuite: group | random_function | prf */ 797 grp = htons(data->group_num); 798 ptr = (u8 *) &cs; 799 os_memcpy(ptr, &grp, sizeof(u16)); 800 ptr += sizeof(u16); 801 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 802 ptr += sizeof(u8); 803 *ptr = EAP_PWD_DEFAULT_PRF; 804 805 /* each component of the cruft will be at most as big as the prime */ 806 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 807 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 808 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 809 goto fin; 810 } 811 812 /* 813 * commit is H(k | peer_element | peer_scalar | server_element | 814 * server_scalar | ciphersuite) 815 */ 816 hash = eap_pwd_h_init(); 817 if (hash == NULL) 818 goto fin; 819 820 /* k */ 821 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 822 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 823 BN_bn2bin(data->k, cruft + offset); 824 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 825 826 /* peer element: x, y */ 827 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 828 data->peer_element, x, y, 829 data->bnctx)) { 830 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 831 "assignment fail"); 832 goto fin; 833 } 834 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 835 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 836 BN_bn2bin(x, cruft + offset); 837 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 838 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 839 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 840 BN_bn2bin(y, cruft + offset); 841 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 842 843 /* peer scalar */ 844 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 845 offset = BN_num_bytes(data->grp->order) - 846 BN_num_bytes(data->peer_scalar); 847 BN_bn2bin(data->peer_scalar, cruft + offset); 848 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 849 850 /* server element: x, y */ 851 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 852 data->my_element, x, y, 853 data->bnctx)) { 854 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 855 "assignment fail"); 856 goto fin; 857 } 858 859 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 860 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 861 BN_bn2bin(x, cruft + offset); 862 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 863 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 864 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 865 BN_bn2bin(y, cruft + offset); 866 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 867 868 /* server scalar */ 869 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 870 offset = BN_num_bytes(data->grp->order) - 871 BN_num_bytes(data->my_scalar); 872 BN_bn2bin(data->my_scalar, cruft + offset); 873 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 874 875 /* ciphersuite */ 876 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 877 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 878 879 /* all done */ 880 eap_pwd_h_final(hash, conf); 881 882 ptr = (u8 *) payload; 883 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 884 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 885 "verify"); 886 goto fin; 887 } 888 889 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 890 if (compute_keys(data->grp, data->bnctx, data->k, 891 data->peer_scalar, data->my_scalar, conf, 892 data->my_confirm, &cs, data->msk, data->emsk, 893 data->session_id) < 0) 894 eap_pwd_state(data, FAILURE); 895 else 896 eap_pwd_state(data, SUCCESS); 897 898 fin: 899 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 900 BN_clear_free(x); 901 BN_clear_free(y); 902 } 903 904 905 static void eap_pwd_process(struct eap_sm *sm, void *priv, 906 struct wpabuf *respData) 907 { 908 struct eap_pwd_data *data = priv; 909 const u8 *pos; 910 size_t len; 911 u8 lm_exch; 912 u16 tot_len; 913 914 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 915 if ((pos == NULL) || (len < 1)) { 916 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 917 (pos == NULL) ? "is NULL" : "is not NULL", 918 (int) len); 919 return; 920 } 921 922 lm_exch = *pos; 923 pos++; /* skip over the bits and the exch */ 924 len--; 925 926 /* 927 * if we're fragmenting then this should be an ACK with no data, 928 * just return and continue fragmenting in the "build" section above 929 */ 930 if (data->out_frag_pos) { 931 if (len > 1) 932 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 933 "Fragmenting but not an ACK"); 934 else 935 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 936 "peer"); 937 return; 938 } 939 /* 940 * if we're receiving fragmented packets then we need to buffer... 941 * 942 * the first fragment has a total length 943 */ 944 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 945 if (len < 2) { 946 wpa_printf(MSG_DEBUG, 947 "EAP-pwd: Frame too short to contain Total-Length field"); 948 return; 949 } 950 tot_len = WPA_GET_BE16(pos); 951 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 952 "length = %d", tot_len); 953 if (tot_len > 15000) 954 return; 955 if (data->inbuf) { 956 wpa_printf(MSG_DEBUG, 957 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use"); 958 return; 959 } 960 data->inbuf = wpabuf_alloc(tot_len); 961 if (data->inbuf == NULL) { 962 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 963 "buffer fragments!"); 964 return; 965 } 966 data->in_frag_pos = 0; 967 pos += sizeof(u16); 968 len -= sizeof(u16); 969 } 970 /* 971 * the first and all intermediate fragments have the M bit set 972 */ 973 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 974 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 975 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 976 "attack detected! (%d+%d > %d)", 977 (int) data->in_frag_pos, (int) len, 978 (int) wpabuf_size(data->inbuf)); 979 eap_pwd_state(data, FAILURE); 980 return; 981 } 982 wpabuf_put_data(data->inbuf, pos, len); 983 data->in_frag_pos += len; 984 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 985 (int) len); 986 return; 987 } 988 /* 989 * last fragment won't have the M bit set (but we're obviously 990 * buffering fragments so that's how we know it's the last) 991 */ 992 if (data->in_frag_pos) { 993 wpabuf_put_data(data->inbuf, pos, len); 994 data->in_frag_pos += len; 995 pos = wpabuf_head_u8(data->inbuf); 996 len = data->in_frag_pos; 997 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 998 (int) len); 999 } 1000 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 1001 case EAP_PWD_OPCODE_ID_EXCH: 1002 eap_pwd_process_id_resp(sm, data, pos, len); 1003 break; 1004 case EAP_PWD_OPCODE_COMMIT_EXCH: 1005 eap_pwd_process_commit_resp(sm, data, pos, len); 1006 break; 1007 case EAP_PWD_OPCODE_CONFIRM_EXCH: 1008 eap_pwd_process_confirm_resp(sm, data, pos, len); 1009 break; 1010 } 1011 /* 1012 * if we had been buffering fragments, here's a great place 1013 * to clean up 1014 */ 1015 if (data->in_frag_pos) { 1016 wpabuf_free(data->inbuf); 1017 data->inbuf = NULL; 1018 data->in_frag_pos = 0; 1019 } 1020 } 1021 1022 1023 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 1024 { 1025 struct eap_pwd_data *data = priv; 1026 u8 *key; 1027 1028 if (data->state != SUCCESS) 1029 return NULL; 1030 1031 key = os_malloc(EAP_MSK_LEN); 1032 if (key == NULL) 1033 return NULL; 1034 1035 os_memcpy(key, data->msk, EAP_MSK_LEN); 1036 *len = EAP_MSK_LEN; 1037 1038 return key; 1039 } 1040 1041 1042 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 1043 { 1044 struct eap_pwd_data *data = priv; 1045 u8 *key; 1046 1047 if (data->state != SUCCESS) 1048 return NULL; 1049 1050 key = os_malloc(EAP_EMSK_LEN); 1051 if (key == NULL) 1052 return NULL; 1053 1054 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 1055 *len = EAP_EMSK_LEN; 1056 1057 return key; 1058 } 1059 1060 1061 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1062 { 1063 struct eap_pwd_data *data = priv; 1064 return data->state == SUCCESS; 1065 } 1066 1067 1068 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1069 { 1070 struct eap_pwd_data *data = priv; 1071 return (data->state == SUCCESS) || (data->state == FAILURE); 1072 } 1073 1074 1075 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 1076 { 1077 struct eap_pwd_data *data = priv; 1078 u8 *id; 1079 1080 if (data->state != SUCCESS) 1081 return NULL; 1082 1083 id = os_malloc(1 + SHA256_MAC_LEN); 1084 if (id == NULL) 1085 return NULL; 1086 1087 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN); 1088 *len = 1 + SHA256_MAC_LEN; 1089 1090 return id; 1091 } 1092 1093 1094 int eap_server_pwd_register(void) 1095 { 1096 struct eap_method *eap; 1097 int ret; 1098 struct timeval tp; 1099 struct timezone tz; 1100 u32 sr; 1101 1102 sr = 0xdeaddada; 1103 (void) gettimeofday(&tp, &tz); 1104 sr ^= (tp.tv_sec ^ tp.tv_usec); 1105 srandom(sr); 1106 1107 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1108 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1109 "PWD"); 1110 if (eap == NULL) 1111 return -1; 1112 1113 eap->init = eap_pwd_init; 1114 eap->reset = eap_pwd_reset; 1115 eap->buildReq = eap_pwd_build_req; 1116 eap->check = eap_pwd_check; 1117 eap->process = eap_pwd_process; 1118 eap->isDone = eap_pwd_is_done; 1119 eap->getKey = eap_pwd_getkey; 1120 eap->get_emsk = eap_pwd_get_emsk; 1121 eap->isSuccess = eap_pwd_is_success; 1122 eap->getSessionId = eap_pwd_get_session_id; 1123 1124 ret = eap_server_method_register(eap); 1125 if (ret) 1126 eap_server_method_free(eap); 1127 return ret; 1128 } 1129 1130
