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