eap_server_pwd.c revision 7f0b69e88015ca077ef7a417fde0a76c10df23a5
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 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 134static 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 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 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 286fin: 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 296static 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 412fin: 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 421static struct wpabuf * 422eap_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 542static 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 577static 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 629static void 630eap_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; 637 638 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 639 640 if (((data->peer_scalar = BN_new()) == NULL) || 641 ((data->k = BN_new()) == NULL) || 642 ((cofactor = BN_new()) == NULL) || 643 ((x = BN_new()) == NULL) || 644 ((y = BN_new()) == NULL) || 645 ((point = EC_POINT_new(data->grp->group)) == NULL) || 646 ((K = EC_POINT_new(data->grp->group)) == NULL) || 647 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 648 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 649 "fail"); 650 goto fin; 651 } 652 653 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 654 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 655 "cofactor for curve"); 656 goto fin; 657 } 658 659 /* element, x then y, followed by scalar */ 660 ptr = (u8 *) payload; 661 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 662 ptr += BN_num_bytes(data->grp->prime); 663 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 664 ptr += BN_num_bytes(data->grp->prime); 665 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 666 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 667 data->peer_element, x, y, 668 data->bnctx)) { 669 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 670 "fail"); 671 goto fin; 672 } 673 674 /* check to ensure peer's element is not in a small sub-group */ 675 if (BN_cmp(cofactor, BN_value_one())) { 676 if (!EC_POINT_mul(data->grp->group, point, NULL, 677 data->peer_element, cofactor, NULL)) { 678 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 679 "multiply peer element by order"); 680 goto fin; 681 } 682 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 683 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 684 "is at infinity!\n"); 685 goto fin; 686 } 687 } 688 689 /* compute the shared key, k */ 690 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 691 data->peer_scalar, data->bnctx)) || 692 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 693 data->bnctx)) || 694 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 695 data->bnctx))) { 696 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 697 "fail"); 698 goto fin; 699 } 700 701 /* ensure that the shared key isn't in a small sub-group */ 702 if (BN_cmp(cofactor, BN_value_one())) { 703 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 704 NULL)) { 705 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 706 "multiply shared key point by order!\n"); 707 goto fin; 708 } 709 } 710 711 /* 712 * This check is strictly speaking just for the case above where 713 * co-factor > 1 but it was suggested that even though this is probably 714 * never going to happen it is a simple and safe check "just to be 715 * sure" so let's be safe. 716 */ 717 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 718 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 719 "at infinity"); 720 goto fin; 721 } 722 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 723 NULL, data->bnctx)) { 724 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 725 "shared secret from secret point"); 726 goto fin; 727 } 728 res = 1; 729 730fin: 731 EC_POINT_clear_free(K); 732 EC_POINT_clear_free(point); 733 BN_clear_free(cofactor); 734 BN_clear_free(x); 735 BN_clear_free(y); 736 737 if (res) 738 eap_pwd_state(data, PWD_Confirm_Req); 739 else 740 eap_pwd_state(data, FAILURE); 741} 742 743 744static void 745eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 746 const u8 *payload, size_t payload_len) 747{ 748 BIGNUM *x = NULL, *y = NULL; 749 struct crypto_hash *hash; 750 u32 cs; 751 u16 grp; 752 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 753 int offset; 754 755 /* build up the ciphersuite: group | random_function | prf */ 756 grp = htons(data->group_num); 757 ptr = (u8 *) &cs; 758 os_memcpy(ptr, &grp, sizeof(u16)); 759 ptr += sizeof(u16); 760 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 761 ptr += sizeof(u8); 762 *ptr = EAP_PWD_DEFAULT_PRF; 763 764 /* each component of the cruft will be at most as big as the prime */ 765 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 766 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 767 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 768 goto fin; 769 } 770 771 /* 772 * commit is H(k | peer_element | peer_scalar | server_element | 773 * server_scalar | ciphersuite) 774 */ 775 hash = eap_pwd_h_init(); 776 if (hash == NULL) 777 goto fin; 778 779 /* k */ 780 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 781 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 782 BN_bn2bin(data->k, cruft + offset); 783 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 784 785 /* peer element: x, y */ 786 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 787 data->peer_element, x, y, 788 data->bnctx)) { 789 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 790 "assignment fail"); 791 goto fin; 792 } 793 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 794 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 795 BN_bn2bin(x, cruft + offset); 796 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 797 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 798 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 799 BN_bn2bin(y, cruft + offset); 800 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 801 802 /* peer scalar */ 803 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 804 offset = BN_num_bytes(data->grp->order) - 805 BN_num_bytes(data->peer_scalar); 806 BN_bn2bin(data->peer_scalar, cruft + offset); 807 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 808 809 /* server element: x, y */ 810 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 811 data->my_element, x, y, 812 data->bnctx)) { 813 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 814 "assignment fail"); 815 goto fin; 816 } 817 818 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 819 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 820 BN_bn2bin(x, cruft + offset); 821 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 822 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 823 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 824 BN_bn2bin(y, cruft + offset); 825 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 826 827 /* server scalar */ 828 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 829 offset = BN_num_bytes(data->grp->order) - 830 BN_num_bytes(data->my_scalar); 831 BN_bn2bin(data->my_scalar, cruft + offset); 832 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 833 834 /* ciphersuite */ 835 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 836 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 837 838 /* all done */ 839 eap_pwd_h_final(hash, conf); 840 841 ptr = (u8 *) payload; 842 if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { 843 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 844 "verify"); 845 goto fin; 846 } 847 848 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 849 if (compute_keys(data->grp, data->bnctx, data->k, 850 data->peer_scalar, data->my_scalar, conf, 851 data->my_confirm, &cs, data->msk, data->emsk, 852 data->session_id) < 0) 853 eap_pwd_state(data, FAILURE); 854 else 855 eap_pwd_state(data, SUCCESS); 856 857fin: 858 bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); 859 BN_clear_free(x); 860 BN_clear_free(y); 861} 862 863 864static void eap_pwd_process(struct eap_sm *sm, void *priv, 865 struct wpabuf *respData) 866{ 867 struct eap_pwd_data *data = priv; 868 const u8 *pos; 869 size_t len; 870 u8 lm_exch; 871 u16 tot_len; 872 873 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 874 if ((pos == NULL) || (len < 1)) { 875 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 876 (pos == NULL) ? "is NULL" : "is not NULL", 877 (int) len); 878 return; 879 } 880 881 lm_exch = *pos; 882 pos++; /* skip over the bits and the exch */ 883 len--; 884 885 /* 886 * if we're fragmenting then this should be an ACK with no data, 887 * just return and continue fragmenting in the "build" section above 888 */ 889 if (data->out_frag_pos) { 890 if (len > 1) 891 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 892 "Fragmenting but not an ACK"); 893 else 894 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 895 "peer"); 896 return; 897 } 898 /* 899 * if we're receiving fragmented packets then we need to buffer... 900 * 901 * the first fragment has a total length 902 */ 903 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 904 tot_len = WPA_GET_BE16(pos); 905 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 906 "length = %d", tot_len); 907 if (tot_len > 15000) 908 return; 909 data->inbuf = wpabuf_alloc(tot_len); 910 if (data->inbuf == NULL) { 911 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 912 "buffer fragments!"); 913 return; 914 } 915 pos += sizeof(u16); 916 len -= sizeof(u16); 917 } 918 /* 919 * the first and all intermediate fragments have the M bit set 920 */ 921 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 922 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 923 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 924 "attack detected! (%d+%d > %d)", 925 (int) data->in_frag_pos, (int) len, 926 (int) wpabuf_size(data->inbuf)); 927 eap_pwd_state(data, FAILURE); 928 return; 929 } 930 wpabuf_put_data(data->inbuf, pos, len); 931 data->in_frag_pos += len; 932 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 933 (int) len); 934 return; 935 } 936 /* 937 * last fragment won't have the M bit set (but we're obviously 938 * buffering fragments so that's how we know it's the last) 939 */ 940 if (data->in_frag_pos) { 941 wpabuf_put_data(data->inbuf, pos, len); 942 data->in_frag_pos += len; 943 pos = wpabuf_head_u8(data->inbuf); 944 len = data->in_frag_pos; 945 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 946 (int) len); 947 } 948 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 949 case EAP_PWD_OPCODE_ID_EXCH: 950 eap_pwd_process_id_resp(sm, data, pos, len); 951 break; 952 case EAP_PWD_OPCODE_COMMIT_EXCH: 953 eap_pwd_process_commit_resp(sm, data, pos, len); 954 break; 955 case EAP_PWD_OPCODE_CONFIRM_EXCH: 956 eap_pwd_process_confirm_resp(sm, data, pos, len); 957 break; 958 } 959 /* 960 * if we had been buffering fragments, here's a great place 961 * to clean up 962 */ 963 if (data->in_frag_pos) { 964 wpabuf_free(data->inbuf); 965 data->inbuf = NULL; 966 data->in_frag_pos = 0; 967 } 968} 969 970 971static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 972{ 973 struct eap_pwd_data *data = priv; 974 u8 *key; 975 976 if (data->state != SUCCESS) 977 return NULL; 978 979 key = os_malloc(EAP_MSK_LEN); 980 if (key == NULL) 981 return NULL; 982 983 os_memcpy(key, data->msk, EAP_MSK_LEN); 984 *len = EAP_MSK_LEN; 985 986 return key; 987} 988 989 990static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 991{ 992 struct eap_pwd_data *data = priv; 993 u8 *key; 994 995 if (data->state != SUCCESS) 996 return NULL; 997 998 key = os_malloc(EAP_EMSK_LEN); 999 if (key == NULL) 1000 return NULL; 1001 1002 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 1003 *len = EAP_EMSK_LEN; 1004 1005 return key; 1006} 1007 1008 1009static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 1010{ 1011 struct eap_pwd_data *data = priv; 1012 return data->state == SUCCESS; 1013} 1014 1015 1016static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1017{ 1018 struct eap_pwd_data *data = priv; 1019 return (data->state == SUCCESS) || (data->state == FAILURE); 1020} 1021 1022 1023int eap_server_pwd_register(void) 1024{ 1025 struct eap_method *eap; 1026 int ret; 1027 struct timeval tp; 1028 struct timezone tz; 1029 u32 sr; 1030 1031 EVP_add_digest(EVP_sha256()); 1032 1033 sr = 0xdeaddada; 1034 (void) gettimeofday(&tp, &tz); 1035 sr ^= (tp.tv_sec ^ tp.tv_usec); 1036 srandom(sr); 1037 1038 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1039 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1040 "PWD"); 1041 if (eap == NULL) 1042 return -1; 1043 1044 eap->init = eap_pwd_init; 1045 eap->reset = eap_pwd_reset; 1046 eap->buildReq = eap_pwd_build_req; 1047 eap->check = eap_pwd_check; 1048 eap->process = eap_pwd_process; 1049 eap->isDone = eap_pwd_is_done; 1050 eap->getKey = eap_pwd_getkey; 1051 eap->get_emsk = eap_pwd_get_emsk; 1052 eap->isSuccess = eap_pwd_is_success; 1053 1054 ret = eap_server_method_register(eap); 1055 if (ret) 1056 eap_server_method_free(eap); 1057 return ret; 1058} 1059 1060