contrib/hostapd/eap_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 "hostapd.h"
  21 #include "common.h"
  22 #include "eap_i.h"
  23 #include "aes_wrap.h"
  24 #include "eap_psk_common.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 = wpa_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         free(data->id_p);
  58         free(data);
  59 }
  60
  61
  62 static u8 * eap_psk_build_1(struct eap_sm *sm, struct eap_psk_data *data,
  63                             int id, size_t *reqDataLen)
  64 {
  65         struct eap_psk_hdr_1 *req;
  66
  67         wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-1 (sending)");
  68
  69         if (hostapd_get_rand(data->rand_s, EAP_PSK_RAND_LEN)) {
  70                 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
  71                 data->state = FAILURE;
  72                 return NULL;
  73         }
  74         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_S (server rand)",
  75                     data->rand_s, EAP_PSK_RAND_LEN);
  76
  77         *reqDataLen = sizeof(*req) + data->id_s_len;
  78         req = malloc(*reqDataLen);
  79         if (req == NULL) {
  80                 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory "
  81                            "request");
  82                 data->state = FAILURE;
  83                 return NULL;
  84         }
  85
  86         req->code = EAP_CODE_REQUEST;
  87         req->identifier = id;
  88         req->length = htons(*reqDataLen);
  89         req->type = EAP_TYPE_PSK;
  90         req->flags = EAP_PSK_FLAGS_SET_T(0); /* T=0 */
  91         memcpy(req->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
  92         memcpy((u8 *) (req + 1), data->id_s, data->id_s_len);
  93
  94         return (u8 *) req;
  95 }
  96
  97
  98 static u8 * eap_psk_build_3(struct eap_sm *sm, struct eap_psk_data *data,
  99                             int id, size_t *reqDataLen)
 100 {
 101         struct eap_psk_hdr_3 *req;
 102         u8 *buf, *pchannel, nonce[16];
 103         size_t buflen;
 104
 105         wpa_printf(MSG_DEBUG, "EAP-PSK: PSK-3 (sending)");
 106
 107         *reqDataLen = sizeof(*req) + 4 + 16 + 1;
 108         req = malloc(*reqDataLen);
 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         req->code = EAP_CODE_REQUEST;
 117         req->identifier = id;
 118         req->length = htons(*reqDataLen);
 119         req->type = EAP_TYPE_PSK;
 120         req->flags = EAP_PSK_FLAGS_SET_T(2); /* T=2 */
 121         memcpy(req->rand_s, data->rand_s, EAP_PSK_RAND_LEN);
 122
 123         /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
 124         buflen = data->id_s_len + EAP_PSK_RAND_LEN;
 125         buf = malloc(buflen);
 126         if (buf == NULL) {
 127                 free(req);
 128                 data->state = FAILURE;
 129                 return NULL;
 130         }
 131         memcpy(buf, data->id_s, data->id_s_len);
 132         memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
 133         omac1_aes_128(data->ak, buf, buflen, req->mac_s);
 134         free(buf);
 135
 136         eap_psk_derive_keys(data->kdk, data->rand_p, data->tek, data->msk,
 137                             data->emsk);
 138         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
 139         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
 140         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
 141
 142         memset(nonce, 0, sizeof(nonce));
 143         pchannel = (u8 *) (req + 1);
 144         memcpy(pchannel, nonce + 12, 4);
 145         memset(pchannel + 4, 0, 16); /* Tag */
 146         pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
 147         wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (plaintext)",
 148                     pchannel, 4 + 16 + 1);
 149         aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), (u8 *) req, 22,
 150                             pchannel + 4 + 16, 1, pchannel + 4);
 151         wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL (encrypted)",
 152                     pchannel, 4 + 16 + 1);
 153
 154         return (u8 *) req;
 155 }
 156
 157
 158 static u8 * eap_psk_buildReq(struct eap_sm *sm, void *priv, int id,
 159                                   size_t *reqDataLen)
 160 {
 161         struct eap_psk_data *data = priv;
 162
 163         switch (data->state) {
 164         case PSK_1:
 165                 return eap_psk_build_1(sm, data, id, reqDataLen);
 166         case PSK_3:
 167                 return eap_psk_build_3(sm, data, id, reqDataLen);
 168         default:
 169                 wpa_printf(MSG_DEBUG, "EAP-PSK: Unknown state %d in buildReq",
 170                            data->state);
 171                 break;
 172         }
 173         return NULL;
 174 }
 175
 176
 177 static Boolean eap_psk_check(struct eap_sm *sm, void *priv,
 178                              u8 *respData, size_t respDataLen)
 179 {
 180         struct eap_psk_data *data = priv;
 181         struct eap_psk_hdr *resp;
 182         size_t len;
 183         u8 t;
 184
 185         resp = (struct eap_psk_hdr *) respData;
 186         if (respDataLen < sizeof(*resp) || resp->type != EAP_TYPE_PSK ||
 187             (len = ntohs(resp->length)) > respDataLen ||
 188             len < sizeof(*resp)) {
 189                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
 190                 return TRUE;
 191         }
 192         t = EAP_PSK_FLAGS_GET_T(resp->flags);
 193
 194         wpa_printf(MSG_DEBUG, "EAP-PSK: received frame: T=%d", t);
 195
 196         if (data->state == PSK_1 && t != 1) {
 197                 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-2 - "
 198                            "ignore T=%d", t);
 199                 return TRUE;
 200         }
 201
 202         if (data->state == PSK_3 && t != 3) {
 203                 wpa_printf(MSG_DEBUG, "EAP-PSK: Expected PSK-4 - "
 204                            "ignore T=%d", t);
 205                 return TRUE;
 206         }
 207
 208         if ((t == 1 && len < sizeof(struct eap_psk_hdr_2)) ||
 209             (t == 3 && len < sizeof(struct eap_psk_hdr_4))) {
 210                 wpa_printf(MSG_DEBUG, "EAP-PSK: Too short frame");
 211                 return TRUE;
 212         }
 213
 214         return FALSE;
 215 }
 216
 217
 218 static void eap_psk_process_2(struct eap_sm *sm,
 219                               struct eap_psk_data *data,
 220                               u8 *respData, size_t respDataLen)
 221 {
 222         struct eap_psk_hdr_2 *resp;
 223         u8 *pos, mac[EAP_PSK_MAC_LEN], *buf;
 224         size_t len, left, buflen;
 225         int i;
 226
 227         if (data->state != PSK_1)
 228                 return;
 229
 230         wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-2");
 231
 232         resp = (struct eap_psk_hdr_2 *) respData;
 233         len = ntohs(resp->length);
 234         pos = (u8 *) (resp + 1);
 235         left = len - sizeof(*resp);
 236
 237         free(data->id_p);
 238         data->id_p = malloc(left);
 239         if (data->id_p == NULL) {
 240                 wpa_printf(MSG_INFO, "EAP-PSK: Failed to allocate memory for "
 241                            "ID_P");
 242                 return;
 243         }
 244         memcpy(data->id_p, pos, left);
 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         eap_psk_key_setup(sm->user->password, data->ak, data->kdk);
 285         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
 286         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
 287
 288         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: RAND_P (client rand)",
 289                     resp->rand_p, EAP_PSK_RAND_LEN);
 290         memcpy(data->rand_p, resp->rand_p, EAP_PSK_RAND_LEN);
 291
 292         /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
 293         buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
 294         buf = malloc(buflen);
 295         if (buf == NULL) {
 296                 data->state = FAILURE;
 297                 return;
 298         }
 299         memcpy(buf, data->id_p, data->id_p_len);
 300         pos = buf + data->id_p_len;
 301         memcpy(pos, data->id_s, data->id_s_len);
 302         pos += data->id_s_len;
 303         memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN);
 304         pos += EAP_PSK_RAND_LEN;
 305         memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
 306         omac1_aes_128(data->ak, buf, buflen, mac);
 307         free(buf);
 308         wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", resp->mac_p, EAP_PSK_MAC_LEN);
 309         if (memcmp(mac, resp->mac_p, EAP_PSK_MAC_LEN) != 0) {
 310                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid MAC_P");
 311                 wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Expected MAC_P",
 312                             mac, EAP_PSK_MAC_LEN);
 313                 data->state = FAILURE;
 314                 return;
 315         }
 316
 317         data->state = PSK_3;
 318 }
 319
 320
 321 static void eap_psk_process_4(struct eap_sm *sm,
 322                               struct eap_psk_data *data,
 323                               u8 *respData, size_t respDataLen)
 324 {
 325         struct eap_psk_hdr_4 *resp;
 326         u8 *pos, *decrypted, nonce[16], *tag;
 327         size_t left;
 328
 329         if (data->state != PSK_3)
 330                 return;
 331
 332         wpa_printf(MSG_DEBUG, "EAP-PSK: Received PSK-4");
 333
 334         resp = (struct eap_psk_hdr_4 *) respData;
 335         pos = (u8 *) (resp + 1);
 336         left = ntohs(resp->length) - sizeof(*resp);
 337
 338         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: Encrypted PCHANNEL", pos, left);
 339
 340         if (left < 4 + 16 + 1) {
 341                 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
 342                            "PSK-4 (len=%lu, expected 21)",
 343                            (unsigned long) left);
 344                 return;
 345         }
 346
 347         if (pos[0] == 0 && pos[1] == 0 && pos[2] == 0 && pos[3] == 0) {
 348                 wpa_printf(MSG_DEBUG, "EAP-PSK: Nonce did not increase");
 349                 return;
 350         }
 351
 352         memset(nonce, 0, 12);
 353         memcpy(nonce + 12, pos, 4);
 354         pos += 4;
 355         left -= 4;
 356         tag = pos;
 357         pos += 16;
 358         left -= 16;
 359
 360         decrypted = malloc(left);
 361         if (decrypted == NULL)
 362                 return;
 363         memcpy(decrypted, pos, left);
 364
 365         if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
 366                                 respData, 22, decrypted, left, tag)) {
 367                 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
 368                 free(decrypted);
 369                 data->state = FAILURE;
 370                 return;
 371         }
 372         wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
 373                     decrypted, left);
 374
 375         /* Verify R flag */
 376         switch (decrypted[0] >> 6) {
 377         case EAP_PSK_R_FLAG_CONT:
 378                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
 379                 data->state = FAILURE;
 380                 break;
 381         case EAP_PSK_R_FLAG_DONE_SUCCESS:
 382                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
 383                 data->state = SUCCESS;
 384                 break;
 385         case EAP_PSK_R_FLAG_DONE_FAILURE:
 386                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
 387                 data->state = FAILURE;
 388                 break;
 389         }
 390         free(decrypted);
 391 }
 392
 393
 394 static void eap_psk_process(struct eap_sm *sm, void *priv,
 395                                  u8 *respData, size_t respDataLen)
 396 {
 397         struct eap_psk_data *data = priv;
 398         struct eap_psk_hdr *resp;
 399
 400         if (sm->user == NULL || sm->user->password == NULL) {
 401                 wpa_printf(MSG_INFO, "EAP-PSK: Plaintext password not "
 402                            "configured");
 403                 data->state = FAILURE;
 404                 return;
 405         }
 406
 407         resp = (struct eap_psk_hdr *) respData;
 408
 409         switch (EAP_PSK_FLAGS_GET_T(resp->flags)) {
 410         case 1:
 411                 eap_psk_process_2(sm, data, respData, respDataLen);
 412                 break;
 413         case 3:
 414                 eap_psk_process_4(sm, data, respData, respDataLen);
 415                 break;
 416         }
 417 }
 418
 419
 420 static Boolean eap_psk_isDone(struct eap_sm *sm, void *priv)
 421 {
 422         struct eap_psk_data *data = priv;
 423         return data->state == SUCCESS || data->state == FAILURE;
 424 }
 425
 426
 427 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
 428 {
 429         struct eap_psk_data *data = priv;
 430         u8 *key;
 431
 432         if (data->state != SUCCESS)
 433                 return NULL;
 434
 435         key = malloc(EAP_MSK_LEN);
 436         if (key == NULL)
 437                 return NULL;
 438         memcpy(key, data->msk, EAP_MSK_LEN);
 439         *len = EAP_MSK_LEN;
 440
 441         return key;
 442 }
 443
 444
 445 static u8 * eap_psk_get_emsk(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 = malloc(EAP_EMSK_LEN);
 454         if (key == NULL)
 455                 return NULL;
 456         memcpy(key, data->emsk, EAP_EMSK_LEN);
 457         *len = EAP_EMSK_LEN;
 458
 459         return key;
 460 }
 461
 462
 463 static Boolean eap_psk_isSuccess(struct eap_sm *sm, void *priv)
 464 {
 465         struct eap_psk_data *data = priv;
 466         return data->state == SUCCESS;
 467 }
 468
 469
 470 int eap_server_psk_register(void)
 471 {
 472         struct eap_method *eap;
 473         int ret;
 474
 475         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
 476                                       EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
 477         if (eap == NULL)
 478                 return -1;
 479
 480         eap->init = eap_psk_init;
 481         eap->reset = eap_psk_reset;
 482         eap->buildReq = eap_psk_buildReq;
 483         eap->check = eap_psk_check;
 484         eap->process = eap_psk_process;
 485         eap->isDone = eap_psk_isDone;
 486         eap->getKey = eap_psk_getKey;
 487         eap->isSuccess = eap_psk_isSuccess;
 488         eap->get_emsk = eap_psk_get_emsk;
 489
 490         ret = eap_server_method_register(eap);
 491         if (ret)
 492                 eap_server_method_free(eap);
 493         return ret;
 494 }