1 /* 2 * hostapd / EAP-pwd (RFC 5931) server 3 * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org> 4 * 5 * This software may be distributed under the terms of the BSD license. 6 * See README for more details. 7 */ 8 9 #include "includes.h" 10 11 #include "common.h" 12 #include "crypto/sha256.h" 13 #include "eap_server/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 u32 token; 28 u16 group_num; 29 EAP_PWD_group *grp; 30 31 struct wpabuf *inbuf; 32 size_t in_frag_pos; 33 struct wpabuf *outbuf; 34 size_t out_frag_pos; 35 size_t mtu; 36 37 BIGNUM *k; 38 BIGNUM *private_value; 39 BIGNUM *peer_scalar; 40 BIGNUM *my_scalar; 41 EC_POINT *my_element; 42 EC_POINT *peer_element; 43 44 u8 my_confirm[SHA256_MAC_LEN]; 45 46 u8 msk[EAP_MSK_LEN]; 47 u8 emsk[EAP_EMSK_LEN]; 48 u8 session_id[1 + SHA256_MAC_LEN]; 49 50 BN_CTX *bnctx; 51 }; 52 53 54 static const char * eap_pwd_state_txt(int state) 55 { 56 switch (state) { 57 case PWD_ID_Req: 58 return "PWD-ID-Req"; 59 case PWD_Commit_Req: 60 return "PWD-Commit-Req"; 61 case PWD_Confirm_Req: 62 return "PWD-Confirm-Req"; 63 case SUCCESS: 64 return "SUCCESS"; 65 case FAILURE: 66 return "FAILURE"; 67 default: 68 return "PWD-Unk"; 69 } 70 } 71 72 73 static void eap_pwd_state(struct eap_pwd_data *data, int state) 74 { 75 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s", 76 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); 77 data->state = state; 78 } 79 80 81 static void * eap_pwd_init(struct eap_sm *sm) 82 { 83 struct eap_pwd_data *data; 84 85 if (sm->user == NULL || sm->user->password == NULL || 86 sm->user->password_len == 0) { 87 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " 88 "configured"); 89 return NULL; 90 } 91 92 data = os_zalloc(sizeof(*data)); 93 if (data == NULL) 94 return NULL; 95 96 data->group_num = sm->pwd_group; 97 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", 98 data->group_num); 99 data->state = PWD_ID_Req; 100 101 data->id_server = (u8 *) os_strdup("server"); 102 if (data->id_server) 103 data->id_server_len = os_strlen((char *) data->id_server); 104 105 data->password = os_malloc(sm->user->password_len); 106 if (data->password == NULL) { 107 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " 108 "fail"); 109 bin_clear_free(data->id_server, data->id_server_len); 110 os_free(data); 111 return NULL; 112 } 113 data->password_len = sm->user->password_len; 114 os_memcpy(data->password, sm->user->password, data->password_len); 115 116 data->bnctx = BN_CTX_new(); 117 if (data->bnctx == NULL) { 118 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); 119 bin_clear_free(data->password, data->password_len); 120 bin_clear_free(data->id_server, data->id_server_len); 121 os_free(data); 122 return NULL; 123 } 124 125 data->in_frag_pos = data->out_frag_pos = 0; 126 data->inbuf = data->outbuf = NULL; 127 /* use default MTU from RFC 5931 if not configured otherwise */ 128 data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020; 129 130 return data; 131 } 132 133 134 static void eap_pwd_reset(struct eap_sm *sm, void *priv) 135 { 136 struct eap_pwd_data *data = priv; 137 138 BN_clear_free(data->private_value); 139 BN_clear_free(data->peer_scalar); 140 BN_clear_free(data->my_scalar); 141 BN_clear_free(data->k); 142 BN_CTX_free(data->bnctx); 143 EC_POINT_clear_free(data->my_element); 144 EC_POINT_clear_free(data->peer_element); 145 bin_clear_free(data->id_peer, data->id_peer_len); 146 bin_clear_free(data->id_server, data->id_server_len); 147 bin_clear_free(data->password, data->password_len); 148 if (data->grp) { 149 EC_GROUP_free(data->grp->group); 150 EC_POINT_clear_free(data->grp->pwe); 151 BN_clear_free(data->grp->order); 152 BN_clear_free(data->grp->prime); 153 os_free(data->grp); 154 } 155 wpabuf_free(data->inbuf); 156 wpabuf_free(data->outbuf); 157 bin_clear_free(data, sizeof(*data)); 158 } 159 160 161 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, 162 u8 id) 163 { 164 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); 165 /* 166 * if we're fragmenting then we already have an id request, just return 167 */ 168 if (data->out_frag_pos) 169 return; 170 171 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + 172 data->id_server_len); 173 if (data->outbuf == NULL) { 174 eap_pwd_state(data, FAILURE); 175 return; 176 } 177 178 /* an lfsr is good enough to generate unpredictable tokens */ 179 data->token = os_random(); 180 wpabuf_put_be16(data->outbuf, data->group_num); 181 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 182 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 183 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); 184 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE); 185 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); 186 } 187 188 189 static void eap_pwd_build_commit_req(struct eap_sm *sm, 190 struct eap_pwd_data *data, u8 id) 191 { 192 BIGNUM *mask = NULL, *x = NULL, *y = NULL; 193 u8 *scalar = NULL, *element = NULL; 194 u16 offset; 195 196 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 197 /* 198 * if we're fragmenting then we already have an commit request, just 199 * return 200 */ 201 if (data->out_frag_pos) 202 return; 203 204 if (((data->private_value = BN_new()) == NULL) || 205 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 206 ((data->my_scalar = BN_new()) == NULL) || 207 ((mask = BN_new()) == NULL)) { 208 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 209 "fail"); 210 goto fin; 211 } 212 213 if (BN_rand_range(data->private_value, data->grp->order) != 1 || 214 BN_rand_range(mask, data->grp->order) != 1 || 215 BN_add(data->my_scalar, data->private_value, mask) != 1 || 216 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 217 data->bnctx) != 1) { 218 wpa_printf(MSG_INFO, 219 "EAP-pwd (server): unable to get randomness"); 220 goto fin; 221 } 222 223 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 224 data->grp->pwe, mask, data->bnctx)) { 225 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 226 "fail"); 227 eap_pwd_state(data, FAILURE); 228 goto fin; 229 } 230 231 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 232 { 233 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 234 "fail"); 235 goto fin; 236 } 237 BN_clear_free(mask); 238 239 if (((x = BN_new()) == NULL) || 240 ((y = BN_new()) == NULL)) { 241 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 242 "fail"); 243 goto fin; 244 } 245 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 246 data->my_element, x, y, 247 data->bnctx)) { 248 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 249 "fail"); 250 goto fin; 251 } 252 253 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 254 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 255 NULL)) { 256 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 257 goto fin; 258 } 259 260 /* 261 * bignums occupy as little memory as possible so one that is 262 * sufficiently smaller than the prime or order might need pre-pending 263 * with zeros. 264 */ 265 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 266 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 267 offset = BN_num_bytes(data->grp->order) - 268 BN_num_bytes(data->my_scalar); 269 BN_bn2bin(data->my_scalar, scalar + offset); 270 271 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 272 BN_bn2bin(x, element + offset); 273 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 274 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 275 276 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + 277 BN_num_bytes(data->grp->order)); 278 if (data->outbuf == NULL) 279 goto fin; 280 281 /* We send the element as (x,y) followed by the scalar */ 282 wpabuf_put_data(data->outbuf, element, 283 2 * BN_num_bytes(data->grp->prime)); 284 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 285 286 fin: 287 os_free(scalar); 288 os_free(element); 289 BN_clear_free(x); 290 BN_clear_free(y); 291 if (data->outbuf == NULL) 292 eap_pwd_state(data, FAILURE); 293 } 294 295 296 static void eap_pwd_build_confirm_req(struct eap_sm *sm, 297 struct eap_pwd_data *data, u8 id) 298 { 299 BIGNUM *x = NULL, *y = NULL; 300 struct crypto_hash *hash; 301 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 302 u16 grp; 303 int offset; 304 305 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 306 /* 307 * if we're fragmenting then we already have an confirm request, just 308 * return 309 */ 310 if (data->out_frag_pos) 311 return; 312 313 /* Each component of the cruft will be at most as big as the prime */ 314 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 315 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 316 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 317 "fail"); 318 goto fin; 319 } 320 321 /* 322 * commit is H(k | server_element | server_scalar | peer_element | 323 * peer_scalar | ciphersuite) 324 */ 325 hash = eap_pwd_h_init(); 326 if (hash == NULL) 327 goto fin; 328 329 /* 330 * Zero the memory each time because this is mod prime math and some 331 * value may start with a few zeros and the previous one did not. 332 * 333 * First is k 334 */ 335 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 336 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 337 BN_bn2bin(data->k, cruft + offset); 338 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 339 340 /* server element: x, y */ 341 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 342 data->my_element, x, y, 343 data->bnctx)) { 344 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 345 "assignment fail"); 346 goto fin; 347 } 348 349 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 350 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 351 BN_bn2bin(x, cruft + offset); 352 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 353 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 354 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 355 BN_bn2bin(y, cruft + offset); 356 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 357 358 /* server scalar */ 359 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 360 offset = BN_num_bytes(data->grp->order) - 361 BN_num_bytes(data->my_scalar); 362 BN_bn2bin(data->my_scalar, cruft + offset); 363 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 364 365 /* peer element: x, y */ 366 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 367 data->peer_element, x, y, 368 data->bnctx)) { 369 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 370 "assignment fail"); 371 goto fin; 372 } 373 374 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 375 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 376 BN_bn2bin(x, cruft + offset); 377 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 378 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 379 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 380 BN_bn2bin(y, cruft + offset); 381 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 382 383 /* peer scalar */ 384 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 385 offset = BN_num_bytes(data->grp->order) - 386 BN_num_bytes(data->peer_scalar); 387 BN_bn2bin(data->peer_scalar, cruft + offset); 388 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 389 390 /* ciphersuite */ 391 grp = htons(data->group_num); 392 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 393 ptr = cruft; 394 os_memcpy(ptr, &grp, sizeof(u16)); 395 ptr += sizeof(u16); 396 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 397 ptr += sizeof(u8); 398 *ptr = EAP_PWD_DEFAULT_PRF; 399 ptr += sizeof(u8); 400 eap_pwd_h_update(hash, cruft, ptr - cruft); 401 402 /* all done with the random function */ 403 eap_pwd_h_final(hash, conf); 404 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 405 406 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 407 if (data->outbuf == NULL) 408 goto fin; 409 410 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 411 412 fin: 413 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 414 BN_clear_free(x); 415 BN_clear_free(y); 416 if (data->outbuf == NULL) 417 eap_pwd_state(data, FAILURE); 418 } 419 420 421 static struct wpabuf * 422 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 423 { 424 struct eap_pwd_data *data = priv; 425 struct wpabuf *req; 426 u8 lm_exch; 427 const u8 *buf; 428 u16 totlen = 0; 429 size_t len; 430 431 /* 432 * if we're buffering response fragments then just ACK 433 */ 434 if (data->in_frag_pos) { 435 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); 436 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 437 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); 438 if (req == NULL) { 439 eap_pwd_state(data, FAILURE); 440 return NULL; 441 } 442 switch (data->state) { 443 case PWD_ID_Req: 444 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 445 break; 446 case PWD_Commit_Req: 447 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 448 break; 449 case PWD_Confirm_Req: 450 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 451 break; 452 default: 453 eap_pwd_state(data, FAILURE); /* just to be sure */ 454 wpabuf_free(req); 455 return NULL; 456 } 457 return req; 458 } 459 460 /* 461 * build the data portion of a request 462 */ 463 switch (data->state) { 464 case PWD_ID_Req: 465 eap_pwd_build_id_req(sm, data, id); 466 lm_exch = EAP_PWD_OPCODE_ID_EXCH; 467 break; 468 case PWD_Commit_Req: 469 eap_pwd_build_commit_req(sm, data, id); 470 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; 471 break; 472 case PWD_Confirm_Req: 473 eap_pwd_build_confirm_req(sm, data, id); 474 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; 475 break; 476 default: 477 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 478 data->state); 479 eap_pwd_state(data, FAILURE); 480 lm_exch = 0; /* hush now, sweet compiler */ 481 break; 482 } 483 484 if (data->state == FAILURE) 485 return NULL; 486 487 /* 488 * determine whether that data needs to be fragmented 489 */ 490 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 491 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 492 len = data->mtu - EAP_PWD_HDR_SIZE; 493 EAP_PWD_SET_MORE_BIT(lm_exch); 494 /* 495 * if this is the first fragment, need to set the M bit 496 * and add the total length to the eap_pwd_hdr 497 */ 498 if (data->out_frag_pos == 0) { 499 EAP_PWD_SET_LENGTH_BIT(lm_exch); 500 totlen = wpabuf_len(data->outbuf) + 501 EAP_PWD_HDR_SIZE + sizeof(u16); 502 len -= sizeof(u16); 503 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " 504 "total length = %d", totlen); 505 } 506 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", 507 (int) len); 508 } 509 510 /* 511 * alloc an eap request and populate it with the data 512 */ 513 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 514 EAP_PWD_HDR_SIZE + len + 515 (totlen ? sizeof(u16) : 0), 516 EAP_CODE_REQUEST, id); 517 if (req == NULL) { 518 eap_pwd_state(data, FAILURE); 519 return NULL; 520 } 521 522 wpabuf_put_u8(req, lm_exch); 523 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) 524 wpabuf_put_be16(req, totlen); 525 526 buf = wpabuf_head_u8(data->outbuf); 527 wpabuf_put_data(req, buf + data->out_frag_pos, len); 528 data->out_frag_pos += len; 529 /* 530 * either not fragged or last fragment, either way free up the data 531 */ 532 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 533 wpabuf_free(data->outbuf); 534 data->outbuf = NULL; 535 data->out_frag_pos = 0; 536 } 537 538 return req; 539 } 540 541 542 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 543 struct wpabuf *respData) 544 { 545 struct eap_pwd_data *data = priv; 546 const u8 *pos; 547 size_t len; 548 549 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 550 if (pos == NULL || len < 1) { 551 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 552 return TRUE; 553 } 554 555 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", 556 EAP_PWD_GET_EXCHANGE(*pos), (int) len); 557 558 if (data->state == PWD_ID_Req && 559 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) 560 return FALSE; 561 562 if (data->state == PWD_Commit_Req && 563 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) 564 return FALSE; 565 566 if (data->state == PWD_Confirm_Req && 567 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) 568 return FALSE; 569 570 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 571 *pos, data->state); 572 573 return TRUE; 574 } 575 576 577 static void eap_pwd_process_id_resp(struct eap_sm *sm, 578 struct eap_pwd_data *data, 579 const u8 *payload, size_t payload_len) 580 { 581 struct eap_pwd_id *id; 582 583 if (payload_len < sizeof(struct eap_pwd_id)) { 584 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 585 return; 586 } 587 588 id = (struct eap_pwd_id *) payload; 589 if ((data->group_num != be_to_host16(id->group_num)) || 590 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 591 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 592 (id->prf != EAP_PWD_DEFAULT_PRF)) { 593 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 594 eap_pwd_state(data, FAILURE); 595 return; 596 } 597 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 598 if (data->id_peer == NULL) { 599 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 600 return; 601 } 602 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 603 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 604 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 605 data->id_peer, data->id_peer_len); 606 607 data->grp = os_zalloc(sizeof(EAP_PWD_group)); 608 if (data->grp == NULL) { 609 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 610 "group"); 611 return; 612 } 613 if (compute_password_element(data->grp, data->group_num, 614 data->password, data->password_len, 615 data->id_server, data->id_server_len, 616 data->id_peer, data->id_peer_len, 617 (u8 *) &data->token)) { 618 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 619 "PWE"); 620 return; 621 } 622 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 623 BN_num_bits(data->grp->prime)); 624 625 eap_pwd_state(data, PWD_Commit_Req); 626 } 627 628 629 static void 630 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 631 const u8 *payload, size_t payload_len) 632 { 633 u8 *ptr; 634 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 635 EC_POINT *K = NULL, *point = NULL; 636 int res = 0; 637 size_t prime_len, order_len; 638 639 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 640 641 prime_len = BN_num_bytes(data->grp->prime); 642 order_len = BN_num_bytes(data->grp->order); 643 644 if (payload_len != 2 * prime_len + order_len) { 645 wpa_printf(MSG_INFO, 646 "EAP-pwd: Unexpected Commit payload length %u (expected %u)", 647 (unsigned int) payload_len, 648 (unsigned int) (2 * prime_len + order_len)); 649 goto fin; 650 } 651 652 if (((data->peer_scalar = BN_new()) == NULL) || 653 ((data->k = BN_new()) == NULL) || 654 ((cofactor = BN_new()) == NULL) || 655 ((x = BN_new()) == NULL) || 656 ((y = BN_new()) == NULL) || 657 ((point = EC_POINT_new(data->grp->group)) == NULL) || 658 ((K = EC_POINT_new(data->grp->group)) == NULL) || 659 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 660 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 661 "fail"); 662 goto fin; 663 } 664 665 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 666 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 667 "cofactor for curve"); 668 goto fin; 669 } 670 671 /* element, x then y, followed by scalar */ 672 ptr = (u8 *) payload; 673 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 674 ptr += BN_num_bytes(data->grp->prime); 675 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 676 ptr += BN_num_bytes(data->grp->prime); 677 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 678 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 679 data->peer_element, x, y, 680 data->bnctx)) { 681 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 682 "fail"); 683 goto fin; 684 } 685 686 /* check to ensure peer's element is not in a small sub-group */ 687 if (BN_cmp(cofactor, BN_value_one())) { 688 if (!EC_POINT_mul(data->grp->group, point, NULL, 689 data->peer_element, cofactor, NULL)) { 690 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 691 "multiply peer element by order"); 692 goto fin; 693 } 694 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 695 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 696 "is at infinity!\n"); 697 goto fin; 698 } 699 } 700 701 /* compute the shared key, k */ 702 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 703 data->peer_scalar, data->bnctx)) || 704 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 705 data->bnctx)) || 706 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 707 data->bnctx))) { 708 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 709 "fail"); 710 goto fin; 711 } 712 713 /* ensure that the shared key isn't in a small sub-group */ 714 if (BN_cmp(cofactor, BN_value_one())) { 715 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 716 NULL)) { 717 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 718 "multiply shared key point by order!\n"); 719 goto fin; 720 } 721 } 722 723 /* 724 * This check is strictly speaking just for the case above where 725 * co-factor > 1 but it was suggested that even though this is probably 726 * never going to happen it is a simple and safe check "just to be 727 * sure" so let's be safe. 728 */ 729 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 730 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 731 "at infinity"); 732 goto fin; 733 } 734 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 735 NULL, data->bnctx)) { 736 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 737 "shared secret from secret point"); 738 goto fin; 739 } 740 res = 1; 741 742 fin: 743 EC_POINT_clear_free(K); 744 EC_POINT_clear_free(point); 745 BN_clear_free(cofactor); 746 BN_clear_free(x); 747 BN_clear_free(y); 748 749 if (res) 750 eap_pwd_state(data, PWD_Confirm_Req); 751 else 752 eap_pwd_state(data, FAILURE); 753 } 754 755 756 static void 757 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 758 const u8 *payload, size_t payload_len) 759 { 760 BIGNUM *x = NULL, *y = NULL; 761 struct crypto_hash *hash; 762 u32 cs; 763 u16 grp; 764 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 765 int offset; 766 767 /* build up the ciphersuite: group | random_function | prf */ 768 grp = htons(data->group_num); 769 ptr = (u8 *) &cs; 770 os_memcpy(ptr, &grp, sizeof(u16)); 771 ptr += sizeof(u16); 772 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 773 ptr += sizeof(u8); 774 *ptr = EAP_PWD_DEFAULT_PRF; 775 776 /* each component of the cruft will be at most as big as the prime */ 777 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 778 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 779 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 780 goto fin; 781 } 782 783 /* 784 * commit is H(k | peer_element | peer_scalar | server_element | 785 * server_scalar | ciphersuite) 786 */ 787 hash = eap_pwd_h_init(); 788 if (hash == NULL) 789 goto fin; 790 791 /* k */ 792 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 793 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 794 BN_bn2bin(data->k, cruft + offset); 795 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 796 797 /* peer element: x, y */ 798 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 799 data->peer_element, x, y, 800 data->bnctx)) { 801 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 802 "assignment fail"); 803 goto fin; 804 } 805 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 806 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 807 BN_bn2bin(x, cruft + offset); 808 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 809 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 810 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 811 BN_bn2bin(y, cruft + offset); 812 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 813 814 /* peer scalar */ 815 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 816 offset = BN_num_bytes(data->grp->order) - 817 BN_num_bytes(data->peer_scalar); 818 BN_bn2bin(data->peer_scalar, cruft + offset); 819 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 820 821 /* server element: x, y */ 822 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 823 data->my_element, x, y, 824 data->bnctx)) { 825 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 826 "assignment fail"); 827 goto fin; 828 } 829 830 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 831 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 832 BN_bn2bin(x, cruft + offset); 833 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 834 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 835 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 836 BN_bn2bin(y, cruft + offset); 837 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 838 839 /* server scalar */ 840 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 841 offset = BN_num_bytes(data->grp->order) - 842 BN_num_bytes(data->my_scalar); 843 BN_bn2bin(data->my_scalar, cruft + offset); 844 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 845 846 /* ciphersuite */ 847 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 848 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 849 850 /* all done */ 851 eap_pwd_h_final(hash, conf); 852 853 ptr = (u8 *) payload; 854 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 855 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 856 "verify"); 857 goto fin; 858 } 859 860 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 861 if (compute_keys(data->grp, data->bnctx, data->k, 862 data->peer_scalar, data->my_scalar, conf, 863 data->my_confirm, &cs, data->msk, data->emsk, 864 data->session_id) < 0) 865 eap_pwd_state(data, FAILURE); 866 else 867 eap_pwd_state(data, SUCCESS); 868 869 fin: 870 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 871 BN_clear_free(x); 872 BN_clear_free(y); 873 } 874 875 876 static void eap_pwd_process(struct eap_sm *sm, void *priv, 877 struct wpabuf *respData) 878 { 879 struct eap_pwd_data *data = priv; 880 const u8 *pos; 881 size_t len; 882 u8 lm_exch; 883 u16 tot_len; 884 885 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 886 if ((pos == NULL) || (len < 1)) { 887 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 888 (pos == NULL) ? "is NULL" : "is not NULL", 889 (int) len); 890 return; 891 } 892 893 lm_exch = *pos; 894 pos++; /* skip over the bits and the exch */ 895 len--; 896 897 /* 898 * if we're fragmenting then this should be an ACK with no data, 899 * just return and continue fragmenting in the "build" section above 900 */ 901 if (data->out_frag_pos) { 902 if (len > 1) 903 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 904 "Fragmenting but not an ACK"); 905 else 906 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 907 "peer"); 908 return; 909 } 910 /* 911 * if we're receiving fragmented packets then we need to buffer... 912 * 913 * the first fragment has a total length 914 */ 915 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 916 if (len < 2) { 917 wpa_printf(MSG_DEBUG, 918 "EAP-pwd: Frame too short to contain Total-Length field"); 919 return; 920 } 921 tot_len = WPA_GET_BE16(pos); 922 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 923 "length = %d", tot_len); 924 if (tot_len > 15000) 925 return; 926 if (data->inbuf) { 927 wpa_printf(MSG_DEBUG, 928 "EAP-pwd: Unexpected new fragment start when previous fragment is still in use"); 929 return; 930 } 931 data->inbuf = wpabuf_alloc(tot_len); 932 if (data->inbuf == NULL) { 933 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 934 "buffer fragments!"); 935 return; 936 } 937 pos += sizeof(u16); 938 len -= sizeof(u16); 939 } 940 /* 941 * the first and all intermediate fragments have the M bit set 942 */ 943 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 944 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 945 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 946 "attack detected! (%d+%d > %d)", 947 (int) data->in_frag_pos, (int) len, 948 (int) wpabuf_size(data->inbuf)); 949 eap_pwd_state(data, FAILURE); 950 return; 951 } 952 wpabuf_put_data(data->inbuf, pos, len); 953 data->in_frag_pos += len; 954 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 955 (int) len); 956 return; 957 } 958 /* 959 * last fragment won't have the M bit set (but we're obviously 960 * buffering fragments so that's how we know it's the last) 961 */ 962 if (data->in_frag_pos) { 963 wpabuf_put_data(data->inbuf, pos, len); 964 data->in_frag_pos += len; 965 pos = wpabuf_head_u8(data->inbuf); 966 len = data->in_frag_pos; 967 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 968 (int) len); 969 } 970 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 971 case EAP_PWD_OPCODE_ID_EXCH: 972 eap_pwd_process_id_resp(sm, data, pos, len); 973 break; 974 case EAP_PWD_OPCODE_COMMIT_EXCH: 975 eap_pwd_process_commit_resp(sm, data, pos, len); 976 break; 977 case EAP_PWD_OPCODE_CONFIRM_EXCH: 978 eap_pwd_process_confirm_resp(sm, data, pos, len); 979 break; 980 } 981 /* 982 * if we had been buffering fragments, here's a great place 983 * to clean up 984 */ 985 if (data->in_frag_pos) { 986 wpabuf_free(data->inbuf); 987 data->inbuf = NULL; 988 data->in_frag_pos = 0; 989 } 990 } 991 992 993 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 994 { 995 struct eap_pwd_data *data = priv; 996 u8 *key; 997 998 if (data->state != SUCCESS) 999 return NULL; 1000 1001 key = os_malloc(EAP_MSK_LEN); 1002 if (key == NULL) 1003 return NULL; 1004 1005 os_memcpy(key, data->msk, EAP_MSK_LEN); 1006 *len = EAP_MSK_LEN; 1007 1008 return key; 1009 } 1010 1011 1012 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 1013 { 1014 struct eap_pwd_data *data = priv; 1015 u8 *key; 1016 1017 if (data->state != SUCCESS) 1018 return NULL; 1019 1020 key = os_malloc(EAP_EMSK_LEN); 1021 if (key == NULL) 1022 return NULL; 1023 1024 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 1025 *len = EAP_EMSK_LEN; 1026 1027 return key; 1028 } 1029 1030 1031 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1032 { 1033 struct eap_pwd_data *data = priv; 1034 return data->state == SUCCESS; 1035 } 1036 1037 1038 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1039 { 1040 struct eap_pwd_data *data = priv; 1041 return (data->state == SUCCESS) || (data->state == FAILURE); 1042 } 1043 1044 1045 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 1046 { 1047 struct eap_pwd_data *data = priv; 1048 u8 *id; 1049 1050 if (data->state != SUCCESS) 1051 return NULL; 1052 1053 id = os_malloc(1 + SHA256_MAC_LEN); 1054 if (id == NULL) 1055 return NULL; 1056 1057 os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN); 1058 *len = 1 + SHA256_MAC_LEN; 1059 1060 return id; 1061 } 1062 1063 1064 int eap_server_pwd_register(void) 1065 { 1066 struct eap_method *eap; 1067 int ret; 1068 struct timeval tp; 1069 struct timezone tz; 1070 u32 sr; 1071 1072 sr = 0xdeaddada; 1073 (void) gettimeofday(&tp, &tz); 1074 sr ^= (tp.tv_sec ^ tp.tv_usec); 1075 srandom(sr); 1076 1077 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1078 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1079 "PWD"); 1080 if (eap == NULL) 1081 return -1; 1082 1083 eap->init = eap_pwd_init; 1084 eap->reset = eap_pwd_reset; 1085 eap->buildReq = eap_pwd_build_req; 1086 eap->check = eap_pwd_check; 1087 eap->process = eap_pwd_process; 1088 eap->isDone = eap_pwd_is_done; 1089 eap->getKey = eap_pwd_getkey; 1090 eap->get_emsk = eap_pwd_get_emsk; 1091 eap->isSuccess = eap_pwd_is_success; 1092 eap->getSessionId = eap_pwd_get_session_id; 1093 1094 ret = eap_server_method_register(eap); 1095 if (ret) 1096 eap_server_method_free(eap); 1097 return ret; 1098 } 1099 1100