eap_server_pwd.c revision 5a1480c7c46c4236d93bfd303dde32062bee04ac
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 17struct 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 54static 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 73static 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 81static 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 os_free(data->id_server); 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 os_free(data->password); 120 os_free(data->id_server); 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 134static void eap_pwd_reset(struct eap_sm *sm, void *priv) 135{ 136 struct eap_pwd_data *data = priv; 137 138 BN_free(data->private_value); 139 BN_free(data->peer_scalar); 140 BN_free(data->my_scalar); 141 BN_free(data->k); 142 BN_CTX_free(data->bnctx); 143 EC_POINT_free(data->my_element); 144 EC_POINT_free(data->peer_element); 145 os_free(data->id_peer); 146 os_free(data->id_server); 147 os_free(data->password); 148 if (data->grp) { 149 EC_GROUP_free(data->grp->group); 150 EC_POINT_free(data->grp->pwe); 151 BN_free(data->grp->order); 152 BN_free(data->grp->prime); 153 os_free(data->grp); 154 } 155 wpabuf_free(data->inbuf); 156 wpabuf_free(data->outbuf); 157 os_free(data); 158} 159 160 161static 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 189static 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 BN_rand_range(data->private_value, data->grp->order); 214 BN_rand_range(mask, data->grp->order); 215 BN_add(data->my_scalar, data->private_value, mask); 216 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 217 data->bnctx); 218 219 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 220 data->grp->pwe, mask, data->bnctx)) { 221 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 222 "fail"); 223 eap_pwd_state(data, FAILURE); 224 goto fin; 225 } 226 227 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 228 { 229 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 230 "fail"); 231 goto fin; 232 } 233 BN_free(mask); 234 235 if (((x = BN_new()) == NULL) || 236 ((y = BN_new()) == NULL)) { 237 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 238 "fail"); 239 goto fin; 240 } 241 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 242 data->my_element, x, y, 243 data->bnctx)) { 244 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 245 "fail"); 246 goto fin; 247 } 248 249 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 250 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 251 NULL)) { 252 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 253 goto fin; 254 } 255 256 /* 257 * bignums occupy as little memory as possible so one that is 258 * sufficiently smaller than the prime or order might need pre-pending 259 * with zeros. 260 */ 261 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 262 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 263 offset = BN_num_bytes(data->grp->order) - 264 BN_num_bytes(data->my_scalar); 265 BN_bn2bin(data->my_scalar, scalar + offset); 266 267 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 268 BN_bn2bin(x, element + offset); 269 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 270 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 271 272 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + 273 BN_num_bytes(data->grp->order)); 274 if (data->outbuf == NULL) 275 goto fin; 276 277 /* We send the element as (x,y) followed by the scalar */ 278 wpabuf_put_data(data->outbuf, element, 279 2 * BN_num_bytes(data->grp->prime)); 280 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 281 282fin: 283 os_free(scalar); 284 os_free(element); 285 BN_free(x); 286 BN_free(y); 287 if (data->outbuf == NULL) 288 eap_pwd_state(data, FAILURE); 289} 290 291 292static void eap_pwd_build_confirm_req(struct eap_sm *sm, 293 struct eap_pwd_data *data, u8 id) 294{ 295 BIGNUM *x = NULL, *y = NULL; 296 struct crypto_hash *hash; 297 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 298 u16 grp; 299 int offset; 300 301 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 302 /* 303 * if we're fragmenting then we already have an confirm request, just 304 * return 305 */ 306 if (data->out_frag_pos) 307 return; 308 309 /* Each component of the cruft will be at most as big as the prime */ 310 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 311 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 312 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 313 "fail"); 314 goto fin; 315 } 316 317 /* 318 * commit is H(k | server_element | server_scalar | peer_element | 319 * peer_scalar | ciphersuite) 320 */ 321 hash = eap_pwd_h_init(); 322 if (hash == NULL) 323 goto fin; 324 325 /* 326 * Zero the memory each time because this is mod prime math and some 327 * value may start with a few zeros and the previous one did not. 328 * 329 * First is k 330 */ 331 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 332 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 333 BN_bn2bin(data->k, cruft + offset); 334 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 335 336 /* server element: x, y */ 337 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 338 data->my_element, x, y, 339 data->bnctx)) { 340 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 341 "assignment fail"); 342 goto fin; 343 } 344 345 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 346 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 347 BN_bn2bin(x, cruft + offset); 348 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 349 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 350 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 351 BN_bn2bin(y, cruft + offset); 352 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 353 354 /* server scalar */ 355 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 356 offset = BN_num_bytes(data->grp->order) - 357 BN_num_bytes(data->my_scalar); 358 BN_bn2bin(data->my_scalar, cruft + offset); 359 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 360 361 /* peer element: x, y */ 362 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 363 data->peer_element, x, y, 364 data->bnctx)) { 365 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 366 "assignment fail"); 367 goto fin; 368 } 369 370 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 371 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 372 BN_bn2bin(x, cruft + offset); 373 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 374 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 375 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 376 BN_bn2bin(y, cruft + offset); 377 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 378 379 /* peer scalar */ 380 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 381 offset = BN_num_bytes(data->grp->order) - 382 BN_num_bytes(data->peer_scalar); 383 BN_bn2bin(data->peer_scalar, cruft + offset); 384 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 385 386 /* ciphersuite */ 387 grp = htons(data->group_num); 388 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 389 ptr = cruft; 390 os_memcpy(ptr, &grp, sizeof(u16)); 391 ptr += sizeof(u16); 392 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 393 ptr += sizeof(u8); 394 *ptr = EAP_PWD_DEFAULT_PRF; 395 ptr += sizeof(u8); 396 eap_pwd_h_update(hash, cruft, ptr - cruft); 397 398 /* all done with the random function */ 399 eap_pwd_h_final(hash, conf); 400 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 401 402 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 403 if (data->outbuf == NULL) 404 goto fin; 405 406 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 407 408fin: 409 os_free(cruft); 410 BN_free(x); 411 BN_free(y); 412 if (data->outbuf == NULL) 413 eap_pwd_state(data, FAILURE); 414} 415 416 417static struct wpabuf * 418eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 419{ 420 struct eap_pwd_data *data = priv; 421 struct wpabuf *req; 422 u8 lm_exch; 423 const u8 *buf; 424 u16 totlen = 0; 425 size_t len; 426 427 /* 428 * if we're buffering response fragments then just ACK 429 */ 430 if (data->in_frag_pos) { 431 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); 432 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 433 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); 434 if (req == NULL) { 435 eap_pwd_state(data, FAILURE); 436 return NULL; 437 } 438 switch (data->state) { 439 case PWD_ID_Req: 440 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 441 break; 442 case PWD_Commit_Req: 443 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 444 break; 445 case PWD_Confirm_Req: 446 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 447 break; 448 default: 449 eap_pwd_state(data, FAILURE); /* just to be sure */ 450 wpabuf_free(req); 451 return NULL; 452 } 453 return req; 454 } 455 456 /* 457 * build the data portion of a request 458 */ 459 switch (data->state) { 460 case PWD_ID_Req: 461 eap_pwd_build_id_req(sm, data, id); 462 lm_exch = EAP_PWD_OPCODE_ID_EXCH; 463 break; 464 case PWD_Commit_Req: 465 eap_pwd_build_commit_req(sm, data, id); 466 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; 467 break; 468 case PWD_Confirm_Req: 469 eap_pwd_build_confirm_req(sm, data, id); 470 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; 471 break; 472 default: 473 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 474 data->state); 475 eap_pwd_state(data, FAILURE); 476 lm_exch = 0; /* hush now, sweet compiler */ 477 break; 478 } 479 480 if (data->state == FAILURE) 481 return NULL; 482 483 /* 484 * determine whether that data needs to be fragmented 485 */ 486 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 487 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 488 len = data->mtu - EAP_PWD_HDR_SIZE; 489 EAP_PWD_SET_MORE_BIT(lm_exch); 490 /* 491 * if this is the first fragment, need to set the M bit 492 * and add the total length to the eap_pwd_hdr 493 */ 494 if (data->out_frag_pos == 0) { 495 EAP_PWD_SET_LENGTH_BIT(lm_exch); 496 totlen = wpabuf_len(data->outbuf) + 497 EAP_PWD_HDR_SIZE + sizeof(u16); 498 len -= sizeof(u16); 499 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " 500 "total length = %d", totlen); 501 } 502 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", 503 (int) len); 504 } 505 506 /* 507 * alloc an eap request and populate it with the data 508 */ 509 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 510 EAP_PWD_HDR_SIZE + len + 511 (totlen ? sizeof(u16) : 0), 512 EAP_CODE_REQUEST, id); 513 if (req == NULL) { 514 eap_pwd_state(data, FAILURE); 515 return NULL; 516 } 517 518 wpabuf_put_u8(req, lm_exch); 519 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) 520 wpabuf_put_be16(req, totlen); 521 522 buf = wpabuf_head_u8(data->outbuf); 523 wpabuf_put_data(req, buf + data->out_frag_pos, len); 524 data->out_frag_pos += len; 525 /* 526 * either not fragged or last fragment, either way free up the data 527 */ 528 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 529 wpabuf_free(data->outbuf); 530 data->outbuf = NULL; 531 data->out_frag_pos = 0; 532 } 533 534 return req; 535} 536 537 538static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 539 struct wpabuf *respData) 540{ 541 struct eap_pwd_data *data = priv; 542 const u8 *pos; 543 size_t len; 544 545 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 546 if (pos == NULL || len < 1) { 547 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 548 return TRUE; 549 } 550 551 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", 552 EAP_PWD_GET_EXCHANGE(*pos), (int) len); 553 554 if (data->state == PWD_ID_Req && 555 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) 556 return FALSE; 557 558 if (data->state == PWD_Commit_Req && 559 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) 560 return FALSE; 561 562 if (data->state == PWD_Confirm_Req && 563 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) 564 return FALSE; 565 566 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 567 *pos, data->state); 568 569 return TRUE; 570} 571 572 573static void eap_pwd_process_id_resp(struct eap_sm *sm, 574 struct eap_pwd_data *data, 575 const u8 *payload, size_t payload_len) 576{ 577 struct eap_pwd_id *id; 578 579 if (payload_len < sizeof(struct eap_pwd_id)) { 580 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 581 return; 582 } 583 584 id = (struct eap_pwd_id *) payload; 585 if ((data->group_num != be_to_host16(id->group_num)) || 586 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 587 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 588 (id->prf != EAP_PWD_DEFAULT_PRF)) { 589 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 590 eap_pwd_state(data, FAILURE); 591 return; 592 } 593 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 594 if (data->id_peer == NULL) { 595 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 596 return; 597 } 598 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 599 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 600 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 601 data->id_peer, data->id_peer_len); 602 603 data->grp = os_zalloc(sizeof(EAP_PWD_group)); 604 if (data->grp == NULL) { 605 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 606 "group"); 607 return; 608 } 609 if (compute_password_element(data->grp, data->group_num, 610 data->password, data->password_len, 611 data->id_server, data->id_server_len, 612 data->id_peer, data->id_peer_len, 613 (u8 *) &data->token)) { 614 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 615 "PWE"); 616 return; 617 } 618 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 619 BN_num_bits(data->grp->prime)); 620 621 eap_pwd_state(data, PWD_Commit_Req); 622} 623 624 625static void 626eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 627 const u8 *payload, size_t payload_len) 628{ 629 u8 *ptr; 630 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 631 EC_POINT *K = NULL, *point = NULL; 632 int res = 0; 633 634 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 635 636 if (((data->peer_scalar = BN_new()) == NULL) || 637 ((data->k = BN_new()) == NULL) || 638 ((cofactor = BN_new()) == NULL) || 639 ((x = BN_new()) == NULL) || 640 ((y = BN_new()) == NULL) || 641 ((point = EC_POINT_new(data->grp->group)) == NULL) || 642 ((K = EC_POINT_new(data->grp->group)) == NULL) || 643 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 644 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 645 "fail"); 646 goto fin; 647 } 648 649 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 650 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 651 "cofactor for curve"); 652 goto fin; 653 } 654 655 /* element, x then y, followed by scalar */ 656 ptr = (u8 *) payload; 657 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 658 ptr += BN_num_bytes(data->grp->prime); 659 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 660 ptr += BN_num_bytes(data->grp->prime); 661 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 662 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 663 data->peer_element, x, y, 664 data->bnctx)) { 665 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 666 "fail"); 667 goto fin; 668 } 669 670 /* check to ensure peer's element is not in a small sub-group */ 671 if (BN_cmp(cofactor, BN_value_one())) { 672 if (!EC_POINT_mul(data->grp->group, point, NULL, 673 data->peer_element, cofactor, NULL)) { 674 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 675 "multiply peer element by order"); 676 goto fin; 677 } 678 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 679 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 680 "is at infinity!\n"); 681 goto fin; 682 } 683 } 684 685 /* compute the shared key, k */ 686 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 687 data->peer_scalar, data->bnctx)) || 688 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 689 data->bnctx)) || 690 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 691 data->bnctx))) { 692 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 693 "fail"); 694 goto fin; 695 } 696 697 /* ensure that the shared key isn't in a small sub-group */ 698 if (BN_cmp(cofactor, BN_value_one())) { 699 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 700 NULL)) { 701 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 702 "multiply shared key point by order!\n"); 703 goto fin; 704 } 705 } 706 707 /* 708 * This check is strictly speaking just for the case above where 709 * co-factor > 1 but it was suggested that even though this is probably 710 * never going to happen it is a simple and safe check "just to be 711 * sure" so let's be safe. 712 */ 713 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 714 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 715 "at infinity"); 716 goto fin; 717 } 718 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 719 NULL, data->bnctx)) { 720 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 721 "shared secret from secret point"); 722 goto fin; 723 } 724 res = 1; 725 726fin: 727 EC_POINT_free(K); 728 EC_POINT_free(point); 729 BN_free(cofactor); 730 BN_free(x); 731 BN_free(y); 732 733 if (res) 734 eap_pwd_state(data, PWD_Confirm_Req); 735 else 736 eap_pwd_state(data, FAILURE); 737} 738 739 740static void 741eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 742 const u8 *payload, size_t payload_len) 743{ 744 BIGNUM *x = NULL, *y = NULL; 745 struct crypto_hash *hash; 746 u32 cs; 747 u16 grp; 748 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 749 int offset; 750 751 /* build up the ciphersuite: group | random_function | prf */ 752 grp = htons(data->group_num); 753 ptr = (u8 *) &cs; 754 os_memcpy(ptr, &grp, sizeof(u16)); 755 ptr += sizeof(u16); 756 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 757 ptr += sizeof(u8); 758 *ptr = EAP_PWD_DEFAULT_PRF; 759 760 /* each component of the cruft will be at most as big as the prime */ 761 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 762 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 763 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 764 goto fin; 765 } 766 767 /* 768 * commit is H(k | peer_element | peer_scalar | server_element | 769 * server_scalar | ciphersuite) 770 */ 771 hash = eap_pwd_h_init(); 772 if (hash == NULL) 773 goto fin; 774 775 /* k */ 776 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 777 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 778 BN_bn2bin(data->k, cruft + offset); 779 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 780 781 /* peer element: x, y */ 782 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 783 data->peer_element, x, y, 784 data->bnctx)) { 785 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 786 "assignment fail"); 787 goto fin; 788 } 789 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 790 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 791 BN_bn2bin(x, cruft + offset); 792 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 793 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 794 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 795 BN_bn2bin(y, cruft + offset); 796 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 797 798 /* peer scalar */ 799 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 800 offset = BN_num_bytes(data->grp->order) - 801 BN_num_bytes(data->peer_scalar); 802 BN_bn2bin(data->peer_scalar, cruft + offset); 803 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 804 805 /* server element: x, y */ 806 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 807 data->my_element, x, y, 808 data->bnctx)) { 809 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 810 "assignment fail"); 811 goto fin; 812 } 813 814 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 815 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 816 BN_bn2bin(x, cruft + offset); 817 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 818 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 819 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 820 BN_bn2bin(y, cruft + offset); 821 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 822 823 /* server scalar */ 824 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 825 offset = BN_num_bytes(data->grp->order) - 826 BN_num_bytes(data->my_scalar); 827 BN_bn2bin(data->my_scalar, cruft + offset); 828 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 829 830 /* ciphersuite */ 831 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 832 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 833 834 /* all done */ 835 eap_pwd_h_final(hash, conf); 836 837 ptr = (u8 *) payload; 838 if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) { 839 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 840 "verify"); 841 goto fin; 842 } 843 844 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 845 if (compute_keys(data->grp, data->bnctx, data->k, 846 data->peer_scalar, data->my_scalar, conf, 847 data->my_confirm, &cs, data->msk, data->emsk, 848 data->session_id) < 0) 849 eap_pwd_state(data, FAILURE); 850 else 851 eap_pwd_state(data, SUCCESS); 852 853fin: 854 os_free(cruft); 855 BN_free(x); 856 BN_free(y); 857} 858 859 860static void eap_pwd_process(struct eap_sm *sm, void *priv, 861 struct wpabuf *respData) 862{ 863 struct eap_pwd_data *data = priv; 864 const u8 *pos; 865 size_t len; 866 u8 lm_exch; 867 u16 tot_len; 868 869 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 870 if ((pos == NULL) || (len < 1)) { 871 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 872 (pos == NULL) ? "is NULL" : "is not NULL", 873 (int) len); 874 return; 875 } 876 877 lm_exch = *pos; 878 pos++; /* skip over the bits and the exch */ 879 len--; 880 881 /* 882 * if we're fragmenting then this should be an ACK with no data, 883 * just return and continue fragmenting in the "build" section above 884 */ 885 if (data->out_frag_pos) { 886 if (len > 1) 887 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 888 "Fragmenting but not an ACK"); 889 else 890 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 891 "peer"); 892 return; 893 } 894 /* 895 * if we're receiving fragmented packets then we need to buffer... 896 * 897 * the first fragment has a total length 898 */ 899 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 900 tot_len = WPA_GET_BE16(pos); 901 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 902 "length = %d", tot_len); 903 data->inbuf = wpabuf_alloc(tot_len); 904 if (data->inbuf == NULL) { 905 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 906 "buffer fragments!"); 907 return; 908 } 909 pos += sizeof(u16); 910 len -= sizeof(u16); 911 } 912 /* 913 * the first and all intermediate fragments have the M bit set 914 */ 915 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 916 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 917 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 918 "attack detected! (%d+%d > %d)", 919 (int) data->in_frag_pos, (int) len, 920 (int) wpabuf_size(data->inbuf)); 921 eap_pwd_state(data, FAILURE); 922 return; 923 } 924 wpabuf_put_data(data->inbuf, pos, len); 925 data->in_frag_pos += len; 926 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 927 (int) len); 928 return; 929 } 930 /* 931 * last fragment won't have the M bit set (but we're obviously 932 * buffering fragments so that's how we know it's the last) 933 */ 934 if (data->in_frag_pos) { 935 wpabuf_put_data(data->inbuf, pos, len); 936 data->in_frag_pos += len; 937 pos = wpabuf_head_u8(data->inbuf); 938 len = data->in_frag_pos; 939 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 940 (int) len); 941 } 942 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 943 case EAP_PWD_OPCODE_ID_EXCH: 944 eap_pwd_process_id_resp(sm, data, pos, len); 945 break; 946 case EAP_PWD_OPCODE_COMMIT_EXCH: 947 eap_pwd_process_commit_resp(sm, data, pos, len); 948 break; 949 case EAP_PWD_OPCODE_CONFIRM_EXCH: 950 eap_pwd_process_confirm_resp(sm, data, pos, len); 951 break; 952 } 953 /* 954 * if we had been buffering fragments, here's a great place 955 * to clean up 956 */ 957 if (data->in_frag_pos) { 958 wpabuf_free(data->inbuf); 959 data->inbuf = NULL; 960 data->in_frag_pos = 0; 961 } 962} 963 964 965static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 966{ 967 struct eap_pwd_data *data = priv; 968 u8 *key; 969 970 if (data->state != SUCCESS) 971 return NULL; 972 973 key = os_malloc(EAP_MSK_LEN); 974 if (key == NULL) 975 return NULL; 976 977 os_memcpy(key, data->msk, EAP_MSK_LEN); 978 *len = EAP_MSK_LEN; 979 980 return key; 981} 982 983 984static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 985{ 986 struct eap_pwd_data *data = priv; 987 u8 *key; 988 989 if (data->state != SUCCESS) 990 return NULL; 991 992 key = os_malloc(EAP_EMSK_LEN); 993 if (key == NULL) 994 return NULL; 995 996 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 997 *len = EAP_EMSK_LEN; 998 999 return key; 1000} 1001 1002 1003static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1004{ 1005 struct eap_pwd_data *data = priv; 1006 return data->state == SUCCESS; 1007} 1008 1009 1010static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1011{ 1012 struct eap_pwd_data *data = priv; 1013 return (data->state == SUCCESS) || (data->state == FAILURE); 1014} 1015 1016 1017int eap_server_pwd_register(void) 1018{ 1019 struct eap_method *eap; 1020 int ret; 1021 struct timeval tp; 1022 struct timezone tz; 1023 u32 sr; 1024 1025 EVP_add_digest(EVP_sha256()); 1026 1027 sr = 0xdeaddada; 1028 (void) gettimeofday(&tp, &tz); 1029 sr ^= (tp.tv_sec ^ tp.tv_usec); 1030 srandom(sr); 1031 1032 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1033 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1034 "PWD"); 1035 if (eap == NULL) 1036 return -1; 1037 1038 eap->init = eap_pwd_init; 1039 eap->reset = eap_pwd_reset; 1040 eap->buildReq = eap_pwd_build_req; 1041 eap->check = eap_pwd_check; 1042 eap->process = eap_pwd_process; 1043 eap->isDone = eap_pwd_is_done; 1044 eap->getKey = eap_pwd_getkey; 1045 eap->get_emsk = eap_pwd_get_emsk; 1046 eap->isSuccess = eap_pwd_is_success; 1047 1048 ret = eap_server_method_register(eap); 1049 if (ret) 1050 eap_server_method_free(eap); 1051 return ret; 1052} 1053 1054