contrib/wpa/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, *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
  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         data->id_s = (u8 *) "hostapd";
  42         data->id_s_len = 7;
  43
  44         return data;
  45 }
  46
  47
  48 static 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
  56 static 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
  91 static 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
 151 fail:
 152         wpabuf_free(req);
 153         data->state = FAILURE;
 154         return NULL;
 155 }
 156
 157
 158 static 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
 176 static 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
 215 static 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
 331 static 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
 411 static 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
 440 static 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
 447 static 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
 465 static 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
 483 static 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
 490 int 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 }