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 if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) { 182 wpabuf_free(data->outbuf); 183 data->outbuf = NULL; 184 eap_pwd_state(data, FAILURE); 185 return; 186 } 187 188 wpabuf_put_be16(data->outbuf, data->group_num); 189 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 190 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 191 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); 192 wpabuf_put_u8(data->outbuf, data->password_hash ? EAP_PWD_PREP_MS : 193 EAP_PWD_PREP_NONE); 194 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); 195 } 196 197 198 static void eap_pwd_build_commit_req(struct eap_sm *sm, 199 struct eap_pwd_data *data, u8 id) 200 { 201 BIGNUM *mask = NULL, *x = NULL, *y = NULL; 202 u8 *scalar = NULL, *element = NULL; 203 u16 offset; 204 205 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 206 /* 207 * if we're fragmenting then we already have an commit request, just 208 * return 209 */ 210 if (data->out_frag_pos) 211 return; 212 213 if (((data->private_value = BN_new()) == NULL) || 214 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 215 ((data->my_scalar = BN_new()) == NULL) || 216 ((mask = BN_new()) == NULL)) { 217 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 218 "fail"); 219 goto fin; 220 } 221 222 if (BN_rand_range(data->private_value, data->grp->order) != 1 || 223 BN_rand_range(mask, data->grp->order) != 1 || 224 BN_add(data->my_scalar, data->private_value, mask) != 1 || 225 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 226 data->bnctx) != 1) { 227 wpa_printf(MSG_INFO, 228 "EAP-pwd (server): unable to get randomness"); 229 goto fin; 230 } 231 232 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 233 data->grp->pwe, mask, data->bnctx)) { 234 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 235 "fail"); 236 eap_pwd_state(data, FAILURE); 237 goto fin; 238 } 239 240 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 241 { 242 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 243 "fail"); 244 goto fin; 245 } 246 BN_clear_free(mask); 247 248 if (((x = BN_new()) == NULL) || 249 ((y = BN_new()) == NULL)) { 250 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 251 "fail"); 252 goto fin; 253 } 254 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 255 data->my_element, x, y, 256 data->bnctx)) { 257 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 258 "fail"); 259 goto fin; 260 } 261 262 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 263 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 264 NULL)) { 265 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 266 goto fin; 267 } 268 269 /* 270 * bignums occupy as little memory as possible so one that is 271 * sufficiently smaller than the prime or order might need pre-pending 272 * with zeros. 273 */ 274 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 275 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 276 offset = BN_num_bytes(data->grp->order) - 277 BN_num_bytes(data->my_scalar); 278 BN_bn2bin(data->my_scalar, scalar + offset); 279 280 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 281 BN_bn2bin(x, element + offset); 282 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 283 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 284 285 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + 286 BN_num_bytes(data->grp->order)); 287 if (data->outbuf == NULL) 288 goto fin; 289 290 /* We send the element as (x,y) followed by the scalar */ 291 wpabuf_put_data(data->outbuf, element, 292 2 * BN_num_bytes(data->grp->prime)); 293 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 294 295 fin: 296 os_free(scalar); 297 os_free(element); 298 BN_clear_free(x); 299 BN_clear_free(y); 300 if (data->outbuf == NULL) 301 eap_pwd_state(data, FAILURE); 302 } 303 304 305 static void eap_pwd_build_confirm_req(struct eap_sm *sm, 306 struct eap_pwd_data *data, u8 id) 307 { 308 BIGNUM *x = NULL, *y = NULL; 309 struct crypto_hash *hash; 310 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 311 u16 grp; 312 int offset; 313 314 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 315 /* 316 * if we're fragmenting then we already have an confirm request, just 317 * return 318 */ 319 if (data->out_frag_pos) 320 return; 321 322 /* Each component of the cruft will be at most as big as the prime */ 323 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 324 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 325 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 326 "fail"); 327 goto fin; 328 } 329 330 /* 331 * commit is H(k | server_element | server_scalar | peer_element | 332 * peer_scalar | ciphersuite) 333 */ 334 hash = eap_pwd_h_init(); 335 if (hash == NULL) 336 goto fin; 337 338 /* 339 * Zero the memory each time because this is mod prime math and some 340 * value may start with a few zeros and the previous one did not. 341 * 342 * First is k 343 */ 344 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 345 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 346 BN_bn2bin(data->k, cruft + offset); 347 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 348 349 /* server element: x, y */ 350 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 351 data->my_element, x, y, 352 data->bnctx)) { 353 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 354 "assignment fail"); 355 goto fin; 356 } 357 358 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 359 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 360 BN_bn2bin(x, cruft + offset); 361 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 362 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 363 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 364 BN_bn2bin(y, cruft + offset); 365 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 366 367 /* server scalar */ 368 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 369 offset = BN_num_bytes(data->grp->order) - 370 BN_num_bytes(data->my_scalar); 371 BN_bn2bin(data->my_scalar, cruft + offset); 372 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 373 374 /* peer element: x, y */ 375 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 376 data->peer_element, x, y, 377 data->bnctx)) { 378 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 379 "assignment fail"); 380 goto fin; 381 } 382 383 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 384 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 385 BN_bn2bin(x, cruft + offset); 386 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 387 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 388 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 389 BN_bn2bin(y, cruft + offset); 390 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 391 392 /* peer scalar */ 393 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 394 offset = BN_num_bytes(data->grp->order) - 395 BN_num_bytes(data->peer_scalar); 396 BN_bn2bin(data->peer_scalar, cruft + offset); 397 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 398 399 /* ciphersuite */ 400 grp = htons(data->group_num); 401 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 402 ptr = cruft; 403 os_memcpy(ptr, &grp, sizeof(u16)); 404 ptr += sizeof(u16); 405 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 406 ptr += sizeof(u8); 407 *ptr = EAP_PWD_DEFAULT_PRF; 408 ptr += sizeof(u8); 409 eap_pwd_h_update(hash, cruft, ptr - cruft); 410 411 /* all done with the random function */ 412 eap_pwd_h_final(hash, conf); 413 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 414 415 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 416 if (data->outbuf == NULL) 417 goto fin; 418 419 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 420 421 fin: 422 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 423 BN_clear_free(x); 424 BN_clear_free(y); 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 != 607 data->password_hash ? EAP_PWD_PREP_MS : EAP_PWD_PREP_NONE) { 608 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 609 eap_pwd_state(data, FAILURE); 610 return; 611 } 612 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 613 if (data->id_peer == NULL) { 614 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 615 return; 616 } 617 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 618 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 619 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 620 data->id_peer, data->id_peer_len); 621 622 data->grp = os_zalloc(sizeof(EAP_PWD_group)); 623 if (data->grp == NULL) { 624 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 625 "group"); 626 return; 627 } 628 629 if (data->password_hash) { 630 res = hash_nt_password_hash(data->password, pwhashhash); 631 if (res) 632 return; 633 password = pwhashhash; 634 password_len = sizeof(pwhashhash); 635 } else { 636 password = data->password; 637 password_len = data->password_len; 638 } 639 640 res = compute_password_element(data->grp, data->group_num, 641 password, password_len, 642 data->id_server, data->id_server_len, 643 data->id_peer, data->id_peer_len, 644 (u8 *) &data->token); 645 os_memset(pwhashhash, 0, sizeof(pwhashhash)); 646 if (res) { 647 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 648 "PWE"); 649 return; 650 } 651 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 652 BN_num_bits(data->grp->prime)); 653 654 eap_pwd_state(data, PWD_Commit_Req); 655 } 656 657 658 static void 659 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 660 const u8 *payload, size_t payload_len) 661 { 662 u8 *ptr; 663 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 664 EC_POINT *K = NULL, *point = NULL; 665 int res = 0; 666 size_t prime_len, order_len; 667 668 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 669 670 prime_len = BN_num_bytes(data->grp->prime); 671 order_len = BN_num_bytes(data->grp->order); 672 673 if (payload_len != 2 * prime_len + order_len) { 674 wpa_printf(MSG_INFO, 675 "EAP-pwd: Unexpected Commit payload length %u (expected %u)", 676 (unsigned int) payload_len, 677 (unsigned int) (2 * prime_len + order_len)); 678 goto fin; 679 } 680 681 if (((data->peer_scalar = BN_new()) == NULL) || 682 ((data->k = BN_new()) == NULL) || 683 ((cofactor = BN_new()) == NULL) || 684 ((x = BN_new()) == NULL) || 685 ((y = BN_new()) == NULL) || 686 ((point = EC_POINT_new(data->grp->group)) == NULL) || 687 ((K = EC_POINT_new(data->grp->group)) == NULL) || 688 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 689 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 690 "fail"); 691 goto fin; 692 } 693 694 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 695 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 696 "cofactor for curve"); 697 goto fin; 698 } 699 700 /* element, x then y, followed by scalar */ 701 ptr = (u8 *) payload; 702 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 703 ptr += BN_num_bytes(data->grp->prime); 704 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 705 ptr += BN_num_bytes(data->grp->prime); 706 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 707 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 708 data->peer_element, x, y, 709 data->bnctx)) { 710 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 711 "fail"); 712 goto fin; 713 } 714 715 /* check to ensure peer's element is not in a small sub-group */ 716 if (BN_cmp(cofactor, BN_value_one())) { 717 if (!EC_POINT_mul(data->grp->group, point, NULL, 718 data->peer_element, cofactor, NULL)) { 719 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 720 "multiply peer element by order"); 721 goto fin; 722 } 723 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 724 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 725 "is at infinity!\n"); 726 goto fin; 727 } 728 } 729 730 /* compute the shared key, k */ 731 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 732 data->peer_scalar, data->bnctx)) || 733 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 734 data->bnctx)) || 735 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 736 data->bnctx))) { 737 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 738 "fail"); 739 goto fin; 740 } 741 742 /* ensure that the shared key isn't in a small sub-group */ 743 if (BN_cmp(cofactor, BN_value_one())) { 744 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 745 NULL)) { 746 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 747 "multiply shared key point by order!\n"); 748 goto fin; 749 } 750 } 751 752 /* 753 * This check is strictly speaking just for the case above where 754 * co-factor > 1 but it was suggested that even though this is probably 755 * never going to happen it is a simple and safe check "just to be 756 * sure" so let's be safe. 757 */ 758 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 759 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 760 "at infinity"); 761 goto fin; 762 } 763 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 764 NULL, data->bnctx)) { 765 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 766 "shared secret from secret point"); 767 goto fin; 768 } 769 res = 1; 770 771 fin: 772 EC_POINT_clear_free(K); 773 EC_POINT_clear_free(point); 774 BN_clear_free(cofactor); 775 BN_clear_free(x); 776 BN_clear_free(y); 777 778 if (res) 779 eap_pwd_state(data, PWD_Confirm_Req); 780 else 781 eap_pwd_state(data, FAILURE); 782 } 783 784 785 static void 786 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 787 const u8 *payload, size_t payload_len) 788 { 789 BIGNUM *x = NULL, *y = NULL; 790 struct crypto_hash *hash; 791 u32 cs; 792 u16 grp; 793 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 794 int offset; 795 796 if (payload_len != SHA256_MAC_LEN) { 797 wpa_printf(MSG_INFO, 798 "EAP-pwd: Unexpected Confirm payload length %u (expected %u)", 799 (unsigned int) payload_len, SHA256_MAC_LEN); 800 goto fin; 801 } 802 803 /* build up the ciphersuite: group | random_function | prf */ 804 grp = htons(data->group_num); 805 ptr = (u8 *) &cs; 806 os_memcpy(ptr, &grp, sizeof(u16)); 807 ptr += sizeof(u16); 808 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 809 ptr += sizeof(u8); 810 *ptr = EAP_PWD_DEFAULT_PRF; 811 812 /* each component of the cruft will be at most as big as the prime */ 813 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 814 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 815 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 816 goto fin; 817 } 818 819 /* 820 * commit is H(k | peer_element | peer_scalar | server_element | 821 * server_scalar | ciphersuite) 822 */ 823 hash = eap_pwd_h_init(); 824 if (hash == NULL) 825 goto fin; 826 827 /* k */ 828 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 829 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 830 BN_bn2bin(data->k, cruft + offset); 831 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 832 833 /* peer element: x, y */ 834 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 835 data->peer_element, x, y, 836 data->bnctx)) { 837 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 838 "assignment fail"); 839 goto fin; 840 } 841 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 842 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 843 BN_bn2bin(x, cruft + offset); 844 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 845 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 846 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 847 BN_bn2bin(y, cruft + offset); 848 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 849 850 /* peer scalar */ 851 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 852 offset = BN_num_bytes(data->grp->order) - 853 BN_num_bytes(data->peer_scalar); 854 BN_bn2bin(data->peer_scalar, cruft + offset); 855 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 856 857 /* server element: x, y */ 858 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 859 data->my_element, x, y, 860 data->bnctx)) { 861 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 862 "assignment fail"); 863 goto fin; 864 } 865 866 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 867 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 868 BN_bn2bin(x, cruft + offset); 869 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 870 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 871 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 872 BN_bn2bin(y, cruft + offset); 873 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 874 875 /* server scalar */ 876 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 877 offset = BN_num_bytes(data->grp->order) - 878 BN_num_bytes(data->my_scalar); 879 BN_bn2bin(data->my_scalar, cruft + offset); 880 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 881 882 /* ciphersuite */ 883 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 884 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 885 886 /* all done */ 887 eap_pwd_h_final(hash, conf); 888 889 ptr = (u8 *) payload; 890 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 891 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 892 "verify"); 893 goto fin; 894 } 895 896 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 897 if (compute_keys(data->grp, data->bnctx, data->k, 898 data->peer_scalar, data->my_scalar, conf, 899 data->my_confirm, &cs, data->msk, data->emsk, 900 data->session_id) < 0) 901 eap_pwd_state(data, FAILURE); 902 else 903 eap_pwd_state(data, SUCCESS); 904 905 fin: 906 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 907 BN_clear_free(x); 908 BN_clear_free(y); 909 } 910 911 912 static void eap_pwd_process(struct eap_sm *sm, void *priv, 913 struct wpabuf *respData) 914 { 915 struct eap_pwd_data *data = priv; 916 const u8 *pos; 917 size_t len; 918 u8 lm_exch; 919 u16 tot_len; 920 921 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 922 if ((pos == NULL) || (len < 1)) { 923 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 924 (pos == NULL) ? "is NULL" : "is not NULL", 925 (int) len); 926 return; 927 } 928 929 lm_exch = *pos; 930 pos++; /* skip over the bits and the exch */ 931 len--; 932 933 /* 934 * if we're fragmenting then this should be an ACK with no data, 935 * just return and continue fragmenting in the "build" section above 936 */ 937 if (data->out_frag_pos) { 938 if (len > 1) 939 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 940 "Fragmenting but not an ACK"); 941 else 942 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 943 "peer"); 944 return; 945 } 946 /* 947 * if we're receiving fragmented packets then we need to buffer... 948 * 949 * the first fragment has a total length 950 */ 951 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 952 if (len < 2) { 953 wpa_printf(MSG_DEBUG, 954 "EAP-pwd: Frame too short to contain Total-Length field"); 955 return; 956 } 957 tot_len = WPA_GET_BE16(pos); 958 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 959 "length = %d", tot_len); 960 if (tot_len > 15000) 961 return; 962 if (data->inbuf) { 963 wpa_printf(MSG_DEBUG, 964 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use"); 965 return; 966 } 967 data->inbuf = wpabuf_alloc(tot_len); 968 if (data->inbuf == NULL) { 969 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 970 "buffer fragments!"); 971 return; 972 } 973 data->in_frag_pos = 0; 974 pos += sizeof(u16); 975 len -= sizeof(u16); 976 } 977 /* 978 * the first and all intermediate fragments have the M bit set 979 */ 980 if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) { 981 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 982 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 983 "attack detected! (%d+%d > %d)", 984 (int) data->in_frag_pos, (int) len, 985 (int) wpabuf_size(data->inbuf)); 986 eap_pwd_state(data, FAILURE); 987 return; 988 } 989 wpabuf_put_data(data->inbuf, pos, len); 990 data->in_frag_pos += len; 991 } 992 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 993 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 994 (int) len); 995 return; 996 } 997 /* 998 * last fragment won't have the M bit set (but we're obviously 999 * buffering fragments so that's how we know it's the last) 1000 */ 1001 if (data->in_frag_pos) { 1002 pos = wpabuf_head_u8(data->inbuf); 1003 len = data->in_frag_pos; 1004 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 1005 (int) len); 1006 } 1007 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 1008 case EAP_PWD_OPCODE_ID_EXCH: 1009 eap_pwd_process_id_resp(sm, data, pos, len); 1010 break; 1011 case EAP_PWD_OPCODE_COMMIT_EXCH: 1012 eap_pwd_process_commit_resp(sm, data, pos, len); 1013 break; 1014 case EAP_PWD_OPCODE_CONFIRM_EXCH: 1015 eap_pwd_process_confirm_resp(sm, data, pos, len); 1016 break; 1017 } 1018 /* 1019 * if we had been buffering fragments, here's a great place 1020 * to clean up 1021 */ 1022 if (data->in_frag_pos) { 1023 wpabuf_free(data->inbuf); 1024 data->inbuf = NULL; 1025 data->in_frag_pos = 0; 1026 } 1027 } 1028 1029 1030 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 1031 { 1032 struct eap_pwd_data *data = priv; 1033 u8 *key; 1034 1035 if (data->state != SUCCESS) 1036 return NULL; 1037 1038 key = os_memdup(data->msk, EAP_MSK_LEN); 1039 if (key == NULL) 1040 return NULL; 1041 1042 *len = EAP_MSK_LEN; 1043 1044 return key; 1045 } 1046 1047 1048 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 1049 { 1050 struct eap_pwd_data *data = priv; 1051 u8 *key; 1052 1053 if (data->state != SUCCESS) 1054 return NULL; 1055 1056 key = os_memdup(data->emsk, EAP_EMSK_LEN); 1057 if (key == NULL) 1058 return NULL; 1059 1060 *len = EAP_EMSK_LEN; 1061 1062 return key; 1063 } 1064 1065 1066 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1067 { 1068 struct eap_pwd_data *data = priv; 1069 return data->state == SUCCESS; 1070 } 1071 1072 1073 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1074 { 1075 struct eap_pwd_data *data = priv; 1076 return (data->state == SUCCESS) || (data->state == FAILURE); 1077 } 1078 1079 1080 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 1081 { 1082 struct eap_pwd_data *data = priv; 1083 u8 *id; 1084 1085 if (data->state != SUCCESS) 1086 return NULL; 1087 1088 id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN); 1089 if (id == NULL) 1090 return NULL; 1091 1092 *len = 1 + SHA256_MAC_LEN; 1093 1094 return id; 1095 } 1096 1097 1098 int eap_server_pwd_register(void) 1099 { 1100 struct eap_method *eap; 1101 struct timeval tp; 1102 struct timezone tz; 1103 u32 sr; 1104 1105 sr = 0xdeaddada; 1106 (void) gettimeofday(&tp, &tz); 1107 sr ^= (tp.tv_sec ^ tp.tv_usec); 1108 srandom(sr); 1109 1110 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1111 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1112 "PWD"); 1113 if (eap == NULL) 1114 return -1; 1115 1116 eap->init = eap_pwd_init; 1117 eap->reset = eap_pwd_reset; 1118 eap->buildReq = eap_pwd_build_req; 1119 eap->check = eap_pwd_check; 1120 eap->process = eap_pwd_process; 1121 eap->isDone = eap_pwd_is_done; 1122 eap->getKey = eap_pwd_getkey; 1123 eap->get_emsk = eap_pwd_get_emsk; 1124 eap->isSuccess = eap_pwd_is_success; 1125 eap->getSessionId = eap_pwd_get_session_id; 1126 1127 return eap_server_method_register(eap); 1128 } 1129 1130
