libeap/src/eap_server/eap_server_psk.c

   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_malloc(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         os_memcpy(data->id_p, cpos, left);
 246         data->id_p_len = left;
 247         wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PSK: ID_P",
 248                           data->id_p, data->id_p_len);
 249
 250         if (eap_user_get(sm, data->id_p, data->id_p_len, 0) < 0) {
 251                 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: unknown ID_P",
 252                                   data->id_p, data->id_p_len);
 253                 data->state = FAILURE;
 254                 return;
 255         }
 256
 257         for (i = 0;
 258              i < EAP_MAX_METHODS &&
 259                      (sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
 260                       sm->user->methods[i].method != EAP_TYPE_NONE);
 261              i++) {
 262                 if (sm->user->methods[i].vendor == EAP_VENDOR_IETF &&
 263                     sm->user->methods[i].method == EAP_TYPE_PSK)
 264                         break;
 265         }
 266
 267         if (i >= EAP_MAX_METHODS ||
 268             sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
 269             sm->user->methods[i].method != EAP_TYPE_PSK) {
 270                 wpa_hexdump_ascii(MSG_DEBUG,
 271                                   "EAP-PSK: EAP-PSK not enabled for ID_P",
 272                                   data->id_p, data->id_p_len);
 273                 data->state = FAILURE;
 274                 return;
 275         }
 276
 277         if (sm->user->password == NULL ||
 278             sm->user->password_len != EAP_PSK_PSK_LEN) {
 279                 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: invalid password in "
 280                                   "user database for ID_P",
 281                                   data->id_p, data->id_p_len);
 282                 data->state = FAILURE;
 283                 return;
 284         }
 285         if (eap_psk_key_setup(sm->user->password, data->ak, data->kdk)) {
 286                 data->state = FAILURE;
 287                 return;
 288         }
 289         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
 290         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
 291
 292         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)",
 293                     resp->rand_p, EAP_PSK_RAND_LEN);
 294         os_memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_LEN);
 295
 296         /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
 297         buflen = data->id_p_len + sm->server_id_len + 2 * EAP_PSK_RAND_LEN;
 298         buf = os_malloc(buflen);
 299         if (buf == NULL) {
 300                 data->state = FAILURE;
 301                 return;
 302         }
 303         os_memcpy(buf, data->id_p, data->id_p_len);
 304         pos = buf + data->id_p_len;
 305         os_memcpy(pos, sm->server_id, sm->server_id_len);
 306         pos += sm->server_id_len;
 307         os_memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN);
 308         pos += EAP_PSK_RAND_LEN;
 309         os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
 310         if (omac1_aes_128(data->ak, buf, buflen, mac)) {
 311                 os_free(buf);
 312                 data->state = FAILURE;
 313                 return;
 314         }
 315         os_free(buf);
 316         wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN);
 317         if (os_memcmp_const(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) {
 318                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P");
 319                 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P",
 320                             mac, EAP_PSK_MAC_LEN);
 321                 data->state = FAILURE;
 322                 return;
 323         }
 324
 325         data->state = PSK_3;
 326 }
 327
 328
 329 static void eap_psk_process_4(struct eap_sm *sm,
 330                               struct eap_psk_data *data,
 331                               struct wpabuf *respData)
 332 {
 333         const struct eap_psk_hdr_4 *resp;
 334         u8 *decrypted, nonce[16];
 335         size_t left;
 336         const u8 *pos, *tag;
 337
 338         if (data->state != PSK_3)
 339                 return;
 340
 341         wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4");
 342
 343         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &left);
 344         if (pos == NULL || left < sizeof(*resp)) {
 345                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
 346                 return;
 347         }
 348         resp = (const struct eap_psk_hdr_4 *) pos;
 349         pos = (const u8 *) (resp + 1);
 350         left -= sizeof(*resp);
 351
 352         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left);
 353
 354         if (left < 4 + 16 + 1) {
 355                 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
 356                            "PSK-4 (len=%lu, expected 21)",
 357                            (unsigned long) left);
 358                 return;
 359         }
 360
 361         if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) {
 362                 wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase");
 363                 return;
 364         }
 365
 366         os_memset(nonce, 0, 12);
 367         os_memcpy(nonce + 12, pos, 4);
 368         pos += 4;
 369         left -= 4;
 370         tag = pos;
 371         pos += 16;
 372         left -= 16;
 373
 374         decrypted = os_malloc(left);
 375         if (decrypted == NULL)
 376                 return;
 377         os_memcpy(decrypted, pos, left);
 378
 379         if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
 380                                 wpabuf_head(respData), 22, decrypted, left,
 381                                 tag)) {
 382                 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
 383                 os_free(decrypted);
 384                 data->state = FAILURE;
 385                 return;
 386         }
 387         wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
 388                     decrypted, left);
 389
 390         /* Verify R flag */
 391         switch (decrypted[0] >> 6) {
 392         case EAP_PSK_R_FLAG_CONT:
 393                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
 394                 data->state = FAILURE;
 395                 break;
 396         case EAP_PSK_R_FLAG_DONE_SUCCESS:
 397                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
 398                 data->state = SUCCESS;
 399                 break;
 400         case EAP_PSK_R_FLAG_DONE_FAILURE:
 401                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
 402                 data->state = FAILURE;
 403                 break;
 404         }
 405         os_free(decrypted);
 406 }
 407
 408
 409 static void eap_psk_process(struct eap_sm *sm, void *priv,
 410                             struct wpabuf *respData)
 411 {
 412         struct eap_psk_data *data = priv;
 413         const u8 *pos;
 414         size_t len;
 415
 416         if (sm->user == NULL || sm->user->password == NULL) {
 417                 wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not "
 418                            "configured");
 419                 data->state = FAILURE;
 420                 return;
 421         }
 422
 423         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, respData, &len);
 424         if (pos == NULL || len < 1)
 425                 return;
 426
 427         switch (EAP_PSK_FLAGS_GET_T(*pos)) {
 428         case 1:
 429                 eap_psk_process_2(sm, data, respData);
 430                 break;
 431         case 3:
 432                 eap_psk_process_4(sm, data, respData);
 433                 break;
 434         }
 435 }
 436
 437
 438 static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv)
 439 {
 440         struct eap_psk_data *data = priv;
 441         return data->state == SUCCESS || data->state == FAILURE;
 442 }
 443
 444
 445 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
 446 {
 447         struct eap_psk_data *data = priv;
 448         u8 *key;
 449
 450         if (data->state != SUCCESS)
 451                 return NULL;
 452
 453         key = os_malloc(EAP_MSK_LEN);
 454         if (key == NULL)
 455                 return NULL;
 456         os_memcpy(key, data->msk, EAP_MSK_LEN);
 457         *len = EAP_MSK_LEN;
 458
 459         return key;
 460 }
 461
 462
 463 static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 464 {
 465         struct eap_psk_data *data = priv;
 466         u8 *key;
 467
 468         if (data->state != SUCCESS)
 469                 return NULL;
 470
 471         key = os_malloc(EAP_EMSK_LEN);
 472         if (key == NULL)
 473                 return NULL;
 474         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
 475         *len = EAP_EMSK_LEN;
 476
 477         return key;
 478 }
 479
 480
 481 static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv)
 482 {
 483         struct eap_psk_data *data = priv;
 484         return data->state == SUCCESS;
 485 }
 486
 487
 488 static u8 * eap_psk_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
 489 {
 490         struct eap_psk_data *data = priv;
 491         u8 *id;
 492
 493         if (data->state != SUCCESS)
 494                 return NULL;
 495
 496         *len = 1 + 2 * EAP_PSK_RAND_LEN;
 497         id = os_malloc(*len);
 498         if (id == NULL)
 499                 return NULL;
 500
 501         id[0] = EAP_TYPE_PSK;
 502         os_memcpy(id + 1, data->rand_p, EAP_PSK_RAND_LEN);
 503         os_memcpy(id + 1 + EAP_PSK_RAND_LEN, data->rand_s, EAP_PSK_RAND_LEN);
 504         wpa_hexdump(MSG_DEBUG, "EAP-PSK: Derived Session-Id", id, *len);
 505
 506         return id;
 507 }
 508
 509
 510 int eap_server_psk_register(void)
 511 {
 512         struct eap_method *eap;
 513         int ret;
 514
 515         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
 516                                       EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
 517         if (eap == NULL)
 518                 return -1;
 519
 520         eap->init = eap_psk_init;
 521         eap->reset = eap_psk_reset;
 522         eap->buildReq = eap_psk_buildReq;
 523         eap->check = eap_psk_check;
 524         eap->process = eap_psk_process;
 525         eap->isDone = eap_psk_isDone;
 526         eap->getKey = eap_psk_getKey;
 527         eap->isSuccess = eap_psk_isSuccess;
 528         eap->get_emsk = eap_psk_get_emsk;
 529         eap->getSessionId = eap_psk_get_session_id;
 530
 531         ret = eap_server_method_register(eap);
 532         if (ret)
 533                 eap_server_method_free(eap);
 534         return ret;
 535 }