1 /* 2 * hostapd / EAP-PSK (RFC 4764) server 3 * Copyright (c) 2005-2007, Jouni Malinen <j@w1.fi> 4 * 5 * This software may be distributed under the terms of the BSD license. 6 * See README for more details. 7 * 8 * Note: EAP-PSK is an EAP authentication method and as such, completely 9 * different from WPA-PSK. This file is not needed for WPA-PSK functionality. 10 */ 11 12 #include "includes.h" 13 14 #include "common.h" 15 #include "crypto/aes_wrap.h" 16 #include "crypto/random.h" 17 #include "eap_common/eap_psk_common.h" 18 #include "eap_server/eap_i.h" 19 20 21 struct eap_psk_data { 22 enum { PSK_1, PSK_3, SUCCESS, FAILURE } state; 23 u8 rand_s[EAP_PSK_RAND_LEN]; 24 u8 rand_p[EAP_PSK_RAND_LEN]; 25 u8 *id_p; 26 size_t id_p_len; 27 u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN]; 28 u8 msk[EAP_MSK_LEN]; 29 u8 emsk[EAP_EMSK_LEN]; 30 }; 31 32 33 static void * eap_psk_init(struct eap_sm *sm) 34 { 35 struct eap_psk_data *data; 36 37 data = os_zalloc(sizeof(*data)); 38 if (data == NULL) 39 return NULL; 40 data->state = PSK_1; 41 42 return data; 43 } 44 45 46 static void eap_psk_reset(struct eap_sm *sm, void *priv) 47 { 48 struct eap_psk_data *data = priv; 49 os_free(data->id_p); 50 bin_clear_free(data, sizeof(*data)); 51 } 52 53 54 static struct wpabuf * eap_psk_build_1(struct eap_sm *sm, 55 struct eap_psk_data *data, u8 id) 56 { 57 struct wpabuf *req; 58 struct eap_psk_hdr_1 *psk; 59 60 wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-1 (sending)"); 61 62 if (random_get_bytes(data->rand_s, EAP_PSK_RAND_LEN)) { 63 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data"); 64 data->state = FAILURE; 65 return NULL; 66 } 67 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_S (server rand)", 68 data->rand_s, EAP_PSK_RAND_LEN); 69 70 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, 71 sizeof(*psk) + sm->server_id_len, 72 EAP_CODE_REQUEST, id); 73 if (req == NULL) { 74 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory " 75 "request"); 76 data->state = FAILURE; 77 return NULL; 78 } 79 80 psk = wpabuf_put(req, sizeof(*psk)); 81 psk->flags = EAP_PSK_FLAGS_SET_T(0); /* T=0 */ 82 os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN); 83 wpabuf_put_data(req, sm->server_id, sm->server_id_len); 84 85 return req; 86 } 87 88 89 static struct wpabuf * eap_psk_build_3(struct eap_sm *sm, 90 struct eap_psk_data *data, u8 id) 91 { 92 struct wpabuf *req; 93 struct eap_psk_hdr_3 *psk; 94 u8 *buf, *pchannel, nonce[16]; 95 size_t buflen; 96 97 wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-3 (sending)"); 98 99 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, 100 sizeof(*psk) + 4 + 16 + 1, EAP_CODE_REQUEST, id); 101 if (req == NULL) { 102 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory " 103 "request"); 104 data->state = FAILURE; 105 return NULL; 106 } 107 108 psk = wpabuf_put(req, sizeof(*psk)); 109 psk->flags = EAP_PSK_FLAGS_SET_T(2); /* T=2 */ 110 os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN); 111 112 /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */ 113 buflen = sm->server_id_len + EAP_PSK_RAND_LEN; 114 buf = os_malloc(buflen); 115 if (buf == NULL) 116 goto fail; 117 118 os_memcpy(buf, sm->server_id, sm->server_id_len); 119 os_memcpy(buf + sm->server_id_len, data->rand_p, EAP_PSK_RAND_LEN); 120 if (omac1_aes_128(data->ak, buf, buflen, psk->mac_s)) { 121 os_free(buf); 122 goto fail; 123 } 124 os_free(buf); 125 126 if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek, data->msk, 127 data->emsk)) 128 goto fail; 129 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN); 130 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN); 131 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN); 132 133 os_memset(nonce, 0, sizeof(nonce)); 134 pchannel = wpabuf_put(req, 4 + 16 + 1); 135 os_memcpy(pchannel, nonce + 12, 4); 136 os_memset(pchannel + 4, 0, 16); /* Tag */ 137 pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6; 138 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (plaintext)", 139 pchannel, 4 + 16 + 1); 140 if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), 141 wpabuf_head(req), 22, 142 pchannel + 4 + 16, 1, pchannel + 4)) 143 goto fail; 144 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (encrypted)", 145 pchannel, 4 + 16 + 1); 146 147 return req; 148 149 fail: 150 wpabuf_free(req); 151 data->state = FAILURE; 152 return NULL; 153 } 154 155 156 static struct wpabuf * eap_psk_buildReq(struct eap_sm *sm, void *priv, u8 id) 157 { 158 struct eap_psk_data *data = priv; 159 160 switch (data->state) { 161 case PSK_1: 162 return eap_psk_build_1(sm, data, id); 163 case PSK_3: 164 return eap_psk_build_3(sm, data, id); 165 default: 166 wpa_printf(MSG_DEBUG, "EAP-PSK: Unknown state %d in buildReq", 167 data->state); 168 break; 169 } 170 return NULL; 171 } 172 173 174 static Boolean eap_psk_check(struct eap_sm *sm, void *priv, 175 struct wpabuf *respData) 176 { 177 struct eap_psk_data *data = priv; 178 size_t len; 179 u8 t; 180 const u8 *pos; 181 182 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len); 183 if (pos == NULL || len < 1) { 184 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 185 return TRUE; 186 } 187 t = EAP_PSK_FLAGS_GET_T(*pos); 188 189 wpa_printf(MSG_DEBUG, "EAP-PSK: received frame: T=%d", t); 190 191 if (data->state == PSK_1 && t != 1) { 192 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-2 - " 193 "ignore T=%d", t); 194 return TRUE; 195 } 196 197 if (data->state == PSK_3 && t != 3) { 198 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-4 - " 199 "ignore T=%d", t); 200 return TRUE; 201 } 202 203 if ((t == 1 && len < sizeof(struct eap_psk_hdr_2)) || 204 (t == 3 && len < sizeof(struct eap_psk_hdr_4))) { 205 wpa_printf(MSG_DEBUG, "EAP-PSK: Too short frame"); 206 return TRUE; 207 } 208 209 return FALSE; 210 } 211 212 213 static void eap_psk_process_2(struct eap_sm *sm, 214 struct eap_psk_data *data, 215 struct wpabuf *respData) 216 { 217 const struct eap_psk_hdr_2 *resp; 218 u8 *pos, mac[EAP_PSK_MAC_LEN], *buf; 219 size_t left, buflen; 220 int i; 221 const u8 *cpos; 222 223 if (data->state != PSK_1) 224 return; 225 226 wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-2"); 227 228 cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, 229 &left); 230 if (cpos == NULL || left < sizeof(*resp)) { 231 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 232 return; 233 } 234 resp = (const struct eap_psk_hdr_2 *) cpos; 235 cpos = (const u8 *) (resp + 1); 236 left -= sizeof(*resp); 237 238 os_free(data->id_p); 239 data->id_p = os_memdup(cpos, left); 240 if (data->id_p == NULL) { 241 wpa_printf(MSG_INFO, "EAP-PSK: Failed to allocate memory for " 242 "ID_P"); 243 return; 244 } 245 data->id_p_len = left; 246 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PSK: ID_P", 247 data->id_p, data->id_p_len); 248 249 if (eap_user_get(sm, data->id_p, data->id_p_len, 0) < 0) { 250 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: unknown ID_P", 251 data->id_p, data->id_p_len); 252 data->state = FAILURE; 253 return; 254 } 255 256 for (i = 0; 257 i < EAP_MAX_METHODS && 258 (sm->user->methods[i].vendor != EAP_VENDOR_IETF || 259 sm->user->methods[i].method != EAP_TYPE_NONE); 260 i++) { 261 if (sm->user->methods[i].vendor == EAP_VENDOR_IETF && 262 sm->user->methods[i].method == EAP_TYPE_PSK) 263 break; 264 } 265 266 if (i >= EAP_MAX_METHODS || 267 sm->user->methods[i].vendor != EAP_VENDOR_IETF || 268 sm->user->methods[i].method != EAP_TYPE_PSK) { 269 wpa_hexdump_ascii(MSG_DEBUG, 270 "EAP-PSK: EAP-PSK not enabled for ID_P", 271 data->id_p, data->id_p_len); 272 data->state = FAILURE; 273 return; 274 } 275 276 if (sm->user->password == NULL || 277 sm->user->password_len != EAP_PSK_PSK_LEN) { 278 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: invalid password in " 279 "user database for ID_P", 280 data->id_p, data->id_p_len); 281 data->state = FAILURE; 282 return; 283 } 284 if (eap_psk_key_setup(sm->user->password, data->ak, data->kdk)) { 285 data->state = FAILURE; 286 return; 287 } 288 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN); 289 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN); 290 291 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)", 292 resp->rand_p, EAP_PSK_RAND_LEN); 293 os_memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_LEN); 294 295 /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */ 296 buflen = data->id_p_len + sm->server_id_len + 2 * EAP_PSK_RAND_LEN; 297 buf = os_malloc(buflen); 298 if (buf == NULL) { 299 data->state = FAILURE; 300 return; 301 } 302 os_memcpy(buf, data->id_p, data->id_p_len); 303 pos = buf + data->id_p_len; 304 os_memcpy(pos, sm->server_id, sm->server_id_len); 305 pos += sm->server_id_len; 306 os_memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN); 307 pos += EAP_PSK_RAND_LEN; 308 os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN); 309 if (omac1_aes_128(data->ak, buf, buflen, mac)) { 310 os_free(buf); 311 data->state = FAILURE; 312 return; 313 } 314 os_free(buf); 315 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN); 316 if (os_memcmp_const(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) { 317 wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P"); 318 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P", 319 mac, EAP_PSK_MAC_LEN); 320 data->state = FAILURE; 321 return; 322 } 323 324 data->state = PSK_3; 325 } 326 327 328 static void eap_psk_process_4(struct eap_sm *sm, 329 struct eap_psk_data *data, 330 struct wpabuf *respData) 331 { 332 const struct eap_psk_hdr_4 *resp; 333 u8 *decrypted, nonce[16]; 334 size_t left; 335 const u8 *pos, *tag; 336 337 if (data->state != PSK_3) 338 return; 339 340 wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4"); 341 342 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &left); 343 if (pos == NULL || left < sizeof(*resp)) { 344 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 345 return; 346 } 347 resp = (const struct eap_psk_hdr_4 *) pos; 348 pos = (const u8 *) (resp + 1); 349 left -= sizeof(*resp); 350 351 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left); 352 353 if (left < 4 + 16 + 1) { 354 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in " 355 "PSK-4 (len=%lu, expected 21)", 356 (unsigned long) left); 357 return; 358 } 359 360 if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) { 361 wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase"); 362 return; 363 } 364 365 os_memset(nonce, 0, 12); 366 os_memcpy(nonce + 12, pos, 4); 367 pos += 4; 368 left -= 4; 369 tag = pos; 370 pos += 16; 371 left -= 16; 372 373 decrypted = os_memdup(pos, left); 374 if (decrypted == NULL) 375 return; 376 377 if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce), 378 wpabuf_head(respData), 22, decrypted, left, 379 tag)) { 380 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed"); 381 os_free(decrypted); 382 data->state = FAILURE; 383 return; 384 } 385 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message", 386 decrypted, left); 387 388 /* Verify R flag */ 389 switch (decrypted[0] >> 6) { 390 case EAP_PSK_R_FLAG_CONT: 391 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported"); 392 data->state = FAILURE; 393 break; 394 case EAP_PSK_R_FLAG_DONE_SUCCESS: 395 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS"); 396 data->state = SUCCESS; 397 break; 398 case EAP_PSK_R_FLAG_DONE_FAILURE: 399 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE"); 400 data->state = FAILURE; 401 break; 402 } 403 os_free(decrypted); 404 } 405 406 407 static void eap_psk_process(struct eap_sm *sm, void *priv, 408 struct wpabuf *respData) 409 { 410 struct eap_psk_data *data = priv; 411 const u8 *pos; 412 size_t len; 413 414 if (sm->user == NULL || sm->user->password == NULL) { 415 wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not " 416 "configured"); 417 data->state = FAILURE; 418 return; 419 } 420 421 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len); 422 if (pos == NULL || len < 1) 423 return; 424 425 switch (EAP_PSK_FLAGS_GET_T(*pos)) { 426 case 1: 427 eap_psk_process_2(sm, data, respData); 428 break; 429 case 3: 430 eap_psk_process_4(sm, data, respData); 431 break; 432 } 433 } 434 435 436 static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv) 437 { 438 struct eap_psk_data *data = priv; 439 return data->state == SUCCESS || data->state == FAILURE; 440 } 441 442 443 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len) 444 { 445 struct eap_psk_data *data = priv; 446 u8 *key; 447 448 if (data->state != SUCCESS) 449 return NULL; 450 451 key = os_memdup(data->msk, EAP_MSK_LEN); 452 if (key == NULL) 453 return NULL; 454 *len = EAP_MSK_LEN; 455 456 return key; 457 } 458 459 460 static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 461 { 462 struct eap_psk_data *data = priv; 463 u8 *key; 464 465 if (data->state != SUCCESS) 466 return NULL; 467 468 key = os_memdup(data->emsk, EAP_EMSK_LEN); 469 if (key == NULL) 470 return NULL; 471 *len = EAP_EMSK_LEN; 472 473 return key; 474 } 475 476 477 static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv) 478 { 479 struct eap_psk_data *data = priv; 480 return data->state == SUCCESS; 481 } 482 483 484 static u8 * eap_psk_get_session_id(struct eap_sm *sm, void *priv, size_t *len) 485 { 486 struct eap_psk_data *data = priv; 487 u8 *id; 488 489 if (data->state != SUCCESS) 490 return NULL; 491 492 *len = 1 + 2 * EAP_PSK_RAND_LEN; 493 id = os_malloc(*len); 494 if (id == NULL) 495 return NULL; 496 497 id[0] = EAP_TYPE_PSK; 498 os_memcpy(id + 1, data->rand_p, EAP_PSK_RAND_LEN); 499 os_memcpy(id + 1 + EAP_PSK_RAND_LEN, data->rand_s, EAP_PSK_RAND_LEN); 500 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Derived Session-Id", id, *len); 501 502 return id; 503 } 504 505 506 int eap_server_psk_register(void) 507 { 508 struct eap_method *eap; 509 510 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 511 EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK"); 512 if (eap == NULL) 513 return -1; 514 515 eap->init = eap_psk_init; 516 eap->reset = eap_psk_reset; 517 eap->buildReq = eap_psk_buildReq; 518 eap->check = eap_psk_check; 519 eap->process = eap_psk_process; 520 eap->isDone = eap_psk_isDone; 521 eap->getKey = eap_psk_getKey; 522 eap->isSuccess = eap_psk_isSuccess; 523 eap->get_emsk = eap_psk_get_emsk; 524 eap->getSessionId = eap_psk_get_session_id; 525 526 return eap_server_method_register(eap); 527 } 528