eap_server_psk.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4
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 21struct 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, *id_s; 26 size_t id_p_len, id_s_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 33static 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 data->id_s = (u8 *) "hostapd"; 42 data->id_s_len = 7; 43 44 return data; 45} 46 47 48static void eap_psk_reset(struct eap_sm *sm, void *priv) 49{ 50 struct eap_psk_data *data = priv; 51 os_free(data->id_p); 52 os_free(data); 53} 54 55 56static struct wpabuf * eap_psk_build_1(struct eap_sm *sm, 57 struct eap_psk_data *data, u8 id) 58{ 59 struct wpabuf *req; 60 struct eap_psk_hdr_1 *psk; 61 62 wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-1 (sending)"); 63 64 if (random_get_bytes(data->rand_s, EAP_PSK_RAND_LEN)) { 65 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data"); 66 data->state = FAILURE; 67 return NULL; 68 } 69 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_S (server rand)", 70 data->rand_s, EAP_PSK_RAND_LEN); 71 72 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, 73 sizeof(*psk) + data->id_s_len, 74 EAP_CODE_REQUEST, id); 75 if (req == NULL) { 76 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory " 77 "request"); 78 data->state = FAILURE; 79 return NULL; 80 } 81 82 psk = wpabuf_put(req, sizeof(*psk)); 83 psk->flags = EAP_PSK_FLAGS_SET_T(0); /* T=0 */ 84 os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN); 85 wpabuf_put_data(req, data->id_s, data->id_s_len); 86 87 return req; 88} 89 90 91static struct wpabuf * eap_psk_build_3(struct eap_sm *sm, 92 struct eap_psk_data *data, u8 id) 93{ 94 struct wpabuf *req; 95 struct eap_psk_hdr_3 *psk; 96 u8 *buf, *pchannel, nonce[16]; 97 size_t buflen; 98 99 wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-3 (sending)"); 100 101 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, 102 sizeof(*psk) + 4 + 16 + 1, EAP_CODE_REQUEST, id); 103 if (req == NULL) { 104 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory " 105 "request"); 106 data->state = FAILURE; 107 return NULL; 108 } 109 110 psk = wpabuf_put(req, sizeof(*psk)); 111 psk->flags = EAP_PSK_FLAGS_SET_T(2); /* T=2 */ 112 os_memcpy(psk->rand_s, data->rand_s, EAP_PSK_RAND_LEN); 113 114 /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */ 115 buflen = data->id_s_len + EAP_PSK_RAND_LEN; 116 buf = os_malloc(buflen); 117 if (buf == NULL) 118 goto fail; 119 120 os_memcpy(buf, data->id_s, data->id_s_len); 121 os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN); 122 if (omac1_aes_128(data->ak, buf, buflen, psk->mac_s)) { 123 os_free(buf); 124 goto fail; 125 } 126 os_free(buf); 127 128 if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek, data->msk, 129 data->emsk)) 130 goto fail; 131 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN); 132 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN); 133 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN); 134 135 os_memset(nonce, 0, sizeof(nonce)); 136 pchannel = wpabuf_put(req, 4 + 16 + 1); 137 os_memcpy(pchannel, nonce + 12, 4); 138 os_memset(pchannel + 4, 0, 16); /* Tag */ 139 pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6; 140 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (plaintext)", 141 pchannel, 4 + 16 + 1); 142 if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), 143 wpabuf_head(req), 22, 144 pchannel + 4 + 16, 1, pchannel + 4)) 145 goto fail; 146 wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (encrypted)", 147 pchannel, 4 + 16 + 1); 148 149 return req; 150 151fail: 152 wpabuf_free(req); 153 data->state = FAILURE; 154 return NULL; 155} 156 157 158static struct wpabuf * eap_psk_buildReq(struct eap_sm *sm, void *priv, u8 id) 159{ 160 struct eap_psk_data *data = priv; 161 162 switch (data->state) { 163 case PSK_1: 164 return eap_psk_build_1(sm, data, id); 165 case PSK_3: 166 return eap_psk_build_3(sm, data, id); 167 default: 168 wpa_printf(MSG_DEBUG, "EAP-PSK: Unknown state %d in buildReq", 169 data->state); 170 break; 171 } 172 return NULL; 173} 174 175 176static Boolean eap_psk_check(struct eap_sm *sm, void *priv, 177 struct wpabuf *respData) 178{ 179 struct eap_psk_data *data = priv; 180 size_t len; 181 u8 t; 182 const u8 *pos; 183 184 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len); 185 if (pos == NULL || len < 1) { 186 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 187 return TRUE; 188 } 189 t = EAP_PSK_FLAGS_GET_T(*pos); 190 191 wpa_printf(MSG_DEBUG, "EAP-PSK: received frame: T=%d", t); 192 193 if (data->state == PSK_1 && t != 1) { 194 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-2 - " 195 "ignore T=%d", t); 196 return TRUE; 197 } 198 199 if (data->state == PSK_3 && t != 3) { 200 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-4 - " 201 "ignore T=%d", t); 202 return TRUE; 203 } 204 205 if ((t == 1 && len < sizeof(struct eap_psk_hdr_2)) || 206 (t == 3 && len < sizeof(struct eap_psk_hdr_4))) { 207 wpa_printf(MSG_DEBUG, "EAP-PSK: Too short frame"); 208 return TRUE; 209 } 210 211 return FALSE; 212} 213 214 215static void eap_psk_process_2(struct eap_sm *sm, 216 struct eap_psk_data *data, 217 struct wpabuf *respData) 218{ 219 const struct eap_psk_hdr_2 *resp; 220 u8 *pos, mac[EAP_PSK_MAC_LEN], *buf; 221 size_t left, buflen; 222 int i; 223 const u8 *cpos; 224 225 if (data->state != PSK_1) 226 return; 227 228 wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-2"); 229 230 cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, 231 &left); 232 if (cpos == NULL || left < sizeof(*resp)) { 233 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 234 return; 235 } 236 resp = (const struct eap_psk_hdr_2 *) cpos; 237 cpos = (const u8 *) (resp + 1); 238 left -= sizeof(*resp); 239 240 os_free(data->id_p); 241 data->id_p = os_malloc(left); 242 if (data->id_p == NULL) { 243 wpa_printf(MSG_INFO, "EAP-PSK: Failed to allocate memory for " 244 "ID_P"); 245 return; 246 } 247 os_memcpy(data->id_p, cpos, left); 248 data->id_p_len = left; 249 wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PSK: ID_P", 250 data->id_p, data->id_p_len); 251 252 if (eap_user_get(sm, data->id_p, data->id_p_len, 0) < 0) { 253 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: unknown ID_P", 254 data->id_p, data->id_p_len); 255 data->state = FAILURE; 256 return; 257 } 258 259 for (i = 0; 260 i < EAP_MAX_METHODS && 261 (sm->user->methods[i].vendor != EAP_VENDOR_IETF || 262 sm->user->methods[i].method != EAP_TYPE_NONE); 263 i++) { 264 if (sm->user->methods[i].vendor == EAP_VENDOR_IETF && 265 sm->user->methods[i].method == EAP_TYPE_PSK) 266 break; 267 } 268 269 if (i >= EAP_MAX_METHODS || 270 sm->user->methods[i].vendor != EAP_VENDOR_IETF || 271 sm->user->methods[i].method != EAP_TYPE_PSK) { 272 wpa_hexdump_ascii(MSG_DEBUG, 273 "EAP-PSK: EAP-PSK not enabled for ID_P", 274 data->id_p, data->id_p_len); 275 data->state = FAILURE; 276 return; 277 } 278 279 if (sm->user->password == NULL || 280 sm->user->password_len != EAP_PSK_PSK_LEN) { 281 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: invalid password in " 282 "user database for ID_P", 283 data->id_p, data->id_p_len); 284 data->state = FAILURE; 285 return; 286 } 287 if (eap_psk_key_setup(sm->user->password, data->ak, data->kdk)) { 288 data->state = FAILURE; 289 return; 290 } 291 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN); 292 wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN); 293 294 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)", 295 resp->rand_p, EAP_PSK_RAND_LEN); 296 os_memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_LEN); 297 298 /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */ 299 buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN; 300 buf = os_malloc(buflen); 301 if (buf == NULL) { 302 data->state = FAILURE; 303 return; 304 } 305 os_memcpy(buf, data->id_p, data->id_p_len); 306 pos = buf + data->id_p_len; 307 os_memcpy(pos, data->id_s, data->id_s_len); 308 pos += data->id_s_len; 309 os_memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN); 310 pos += EAP_PSK_RAND_LEN; 311 os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN); 312 if (omac1_aes_128(data->ak, buf, buflen, mac)) { 313 os_free(buf); 314 data->state = FAILURE; 315 return; 316 } 317 os_free(buf); 318 wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN); 319 if (os_memcmp(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) { 320 wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P"); 321 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P", 322 mac, EAP_PSK_MAC_LEN); 323 data->state = FAILURE; 324 return; 325 } 326 327 data->state = PSK_3; 328} 329 330 331static void eap_psk_process_4(struct eap_sm *sm, 332 struct eap_psk_data *data, 333 struct wpabuf *respData) 334{ 335 const struct eap_psk_hdr_4 *resp; 336 u8 *decrypted, nonce[16]; 337 size_t left; 338 const u8 *pos, *tag; 339 340 if (data->state != PSK_3) 341 return; 342 343 wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4"); 344 345 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &left); 346 if (pos == NULL || left < sizeof(*resp)) { 347 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame"); 348 return; 349 } 350 resp = (const struct eap_psk_hdr_4 *) pos; 351 pos = (const u8 *) (resp + 1); 352 left -= sizeof(*resp); 353 354 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left); 355 356 if (left < 4 + 16 + 1) { 357 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in " 358 "PSK-4 (len=%lu, expected 21)", 359 (unsigned long) left); 360 return; 361 } 362 363 if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) { 364 wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase"); 365 return; 366 } 367 368 os_memset(nonce, 0, 12); 369 os_memcpy(nonce + 12, pos, 4); 370 pos += 4; 371 left -= 4; 372 tag = pos; 373 pos += 16; 374 left -= 16; 375 376 decrypted = os_malloc(left); 377 if (decrypted == NULL) 378 return; 379 os_memcpy(decrypted, pos, left); 380 381 if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce), 382 wpabuf_head(respData), 22, decrypted, left, 383 tag)) { 384 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed"); 385 os_free(decrypted); 386 data->state = FAILURE; 387 return; 388 } 389 wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message", 390 decrypted, left); 391 392 /* Verify R flag */ 393 switch (decrypted[0] >> 6) { 394 case EAP_PSK_R_FLAG_CONT: 395 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported"); 396 data->state = FAILURE; 397 break; 398 case EAP_PSK_R_FLAG_DONE_SUCCESS: 399 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS"); 400 data->state = SUCCESS; 401 break; 402 case EAP_PSK_R_FLAG_DONE_FAILURE: 403 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE"); 404 data->state = FAILURE; 405 break; 406 } 407 os_free(decrypted); 408} 409 410 411static void eap_psk_process(struct eap_sm *sm, void *priv, 412 struct wpabuf *respData) 413{ 414 struct eap_psk_data *data = priv; 415 const u8 *pos; 416 size_t len; 417 418 if (sm->user == NULL || sm->user->password == NULL) { 419 wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not " 420 "configured"); 421 data->state = FAILURE; 422 return; 423 } 424 425 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len); 426 if (pos == NULL || len < 1) 427 return; 428 429 switch (EAP_PSK_FLAGS_GET_T(*pos)) { 430 case 1: 431 eap_psk_process_2(sm, data, respData); 432 break; 433 case 3: 434 eap_psk_process_4(sm, data, respData); 435 break; 436 } 437} 438 439 440static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv) 441{ 442 struct eap_psk_data *data = priv; 443 return data->state == SUCCESS || data->state == FAILURE; 444} 445 446 447static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len) 448{ 449 struct eap_psk_data *data = priv; 450 u8 *key; 451 452 if (data->state != SUCCESS) 453 return NULL; 454 455 key = os_malloc(EAP_MSK_LEN); 456 if (key == NULL) 457 return NULL; 458 os_memcpy(key, data->msk, EAP_MSK_LEN); 459 *len = EAP_MSK_LEN; 460 461 return key; 462} 463 464 465static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 466{ 467 struct eap_psk_data *data = priv; 468 u8 *key; 469 470 if (data->state != SUCCESS) 471 return NULL; 472 473 key = os_malloc(EAP_EMSK_LEN); 474 if (key == NULL) 475 return NULL; 476 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 477 *len = EAP_EMSK_LEN; 478 479 return key; 480} 481 482 483static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv) 484{ 485 struct eap_psk_data *data = priv; 486 return data->state == SUCCESS; 487} 488 489 490int eap_server_psk_register(void) 491{ 492 struct eap_method *eap; 493 int ret; 494 495 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 496 EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK"); 497 if (eap == NULL) 498 return -1; 499 500 eap->init = eap_psk_init; 501 eap->reset = eap_psk_reset; 502 eap->buildReq = eap_psk_buildReq; 503 eap->check = eap_psk_check; 504 eap->process = eap_psk_process; 505 eap->isDone = eap_psk_isDone; 506 eap->getKey = eap_psk_getKey; 507 eap->isSuccess = eap_psk_isSuccess; 508 eap->get_emsk = eap_psk_get_emsk; 509 510 ret = eap_server_method_register(eap); 511 if (ret) 512 eap_server_method_free(eap); 513 return ret; 514} 515