contrib/hostapd/src/eap_peer/eap_psk.c

   1 /*
   2  * EAP peer method: EAP-PSK (RFC 4764)
   3  * Copyright (c) 2004-2008, 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 "eap_peer/eap_i.h"
  22 #include "aes_wrap.h"
  23 #include "eap_common/eap_psk_common.h"
  24
  25
  26 struct eap_psk_data {
  27         enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
  28         u8 rand_p[EAP_PSK_RAND_LEN];
  29         u8 ak[EAP_PSK_AK_LEN], kdk[EAP_PSK_KDK_LEN], tek[EAP_PSK_TEK_LEN];
  30         u8 *id_s, *id_p;
  31         size_t id_s_len, id_p_len;
  32         u8 msk[EAP_MSK_LEN];
  33         u8 emsk[EAP_EMSK_LEN];
  34 };
  35
  36
  37 static void * eap_psk_init(struct eap_sm *sm)
  38 {
  39         struct eap_psk_data *data;
  40         const u8 *identity, *password;
  41         size_t identity_len, password_len;
  42
  43         password = eap_get_config_password(sm, &password_len);
  44         if (!password || password_len != 16) {
  45                 wpa_printf(MSG_INFO, "EAP-PSK: 16-octet pre-shared key not "
  46                            "configured");
  47                 return NULL;
  48         }
  49
  50         data = os_zalloc(sizeof(*data));
  51         if (data == NULL)
  52                 return NULL;
  53         if (eap_psk_key_setup(password, data->ak, data->kdk)) {
  54                 os_free(data);
  55                 return NULL;
  56         }
  57         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, EAP_PSK_AK_LEN);
  58         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, EAP_PSK_KDK_LEN);
  59         data->state = PSK_INIT;
  60
  61         identity = eap_get_config_identity(sm, &identity_len);
  62         if (identity) {
  63                 data->id_p = os_malloc(identity_len);
  64                 if (data->id_p)
  65                         os_memcpy(data->id_p, identity, identity_len);
  66                 data->id_p_len = identity_len;
  67         }
  68         if (data->id_p == NULL) {
  69                 wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
  70                 os_free(data);
  71                 return NULL;
  72         }
  73
  74         return data;
  75 }
  76
  77
  78 static void eap_psk_deinit(struct eap_sm *sm, void *priv)
  79 {
  80         struct eap_psk_data *data = priv;
  81         os_free(data->id_s);
  82         os_free(data->id_p);
  83         os_free(data);
  84 }
  85
  86
  87 static struct wpabuf * eap_psk_process_1(struct eap_psk_data *data,
  88                                          struct eap_method_ret *ret,
  89                                          const struct wpabuf *reqData)
  90 {
  91         const struct eap_psk_hdr_1 *hdr1;
  92         struct eap_psk_hdr_2 *hdr2;
  93         struct wpabuf *resp;
  94         u8 *buf, *pos;
  95         size_t buflen, len;
  96         const u8 *cpos;
  97
  98         wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
  99
 100         cpos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
 101         hdr1 = (const struct eap_psk_hdr_1 *) cpos;
 102         if (cpos == NULL || len < sizeof(*hdr1)) {
 103                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
 104                            "length (%lu; expected %lu or more)",
 105                            (unsigned long) len,
 106                            (unsigned long) sizeof(*hdr1));
 107                 ret->ignore = TRUE;
 108                 return NULL;
 109         }
 110         wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
 111         if (EAP_PSK_FLAGS_GET_T(hdr1->flags) != 0) {
 112                 wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
 113                            EAP_PSK_FLAGS_GET_T(hdr1->flags));
 114                 ret->methodState = METHOD_DONE;
 115                 ret->decision = DECISION_FAIL;
 116                 return NULL;
 117         }
 118         wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
 119                     EAP_PSK_RAND_LEN);
 120         os_free(data->id_s);
 121         data->id_s_len = len - sizeof(*hdr1);
 122         data->id_s = os_malloc(data->id_s_len);
 123         if (data->id_s == NULL) {
 124                 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
 125                            "ID_S (len=%lu)", (unsigned long) data->id_s_len);
 126                 ret->ignore = TRUE;
 127                 return NULL;
 128         }
 129         os_memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
 130         wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
 131                           data->id_s, data->id_s_len);
 132
 133         if (os_get_random(data->rand_p, EAP_PSK_RAND_LEN)) {
 134                 wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
 135                 ret->ignore = TRUE;
 136                 return NULL;
 137         }
 138
 139         resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK,
 140                              sizeof(*hdr2) + data->id_p_len, EAP_CODE_RESPONSE,
 141                              eap_get_id(reqData));
 142         if (resp == NULL)
 143                 return NULL;
 144         hdr2 = wpabuf_put(resp, sizeof(*hdr2));
 145         hdr2->flags = EAP_PSK_FLAGS_SET_T(1); /* T=1 */
 146         os_memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
 147         os_memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
 148         wpabuf_put_data(resp, data->id_p, data->id_p_len);
 149         /* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
 150         buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
 151         buf = os_malloc(buflen);
 152         if (buf == NULL) {
 153                 wpabuf_free(resp);
 154                 return NULL;
 155         }
 156         os_memcpy(buf, data->id_p, data->id_p_len);
 157         pos = buf + data->id_p_len;
 158         os_memcpy(pos, data->id_s, data->id_s_len);
 159         pos += data->id_s_len;
 160         os_memcpy(pos, hdr1->rand_s, EAP_PSK_RAND_LEN);
 161         pos += EAP_PSK_RAND_LEN;
 162         os_memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
 163         if (omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p)) {
 164                 os_free(buf);
 165                 wpabuf_free(resp);
 166                 return NULL;
 167         }
 168         os_free(buf);
 169         wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
 170                     EAP_PSK_RAND_LEN);
 171         wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
 172         wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
 173                           data->id_p, data->id_p_len);
 174
 175         data->state = PSK_MAC_SENT;
 176
 177         return resp;
 178 }
 179
 180
 181 static struct wpabuf * eap_psk_process_3(struct eap_psk_data *data,
 182                                          struct eap_method_ret *ret,
 183                                          const struct wpabuf *reqData)
 184 {
 185         const struct eap_psk_hdr_3 *hdr3;
 186         struct eap_psk_hdr_4 *hdr4;
 187         struct wpabuf *resp;
 188         u8 *buf, *rpchannel, nonce[16], *decrypted;
 189         const u8 *pchannel, *tag, *msg;
 190         u8 mac[EAP_PSK_MAC_LEN];
 191         size_t buflen, left, data_len, len, plen;
 192         int failed = 0;
 193         const u8 *pos;
 194
 195         wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
 196
 197         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK,
 198                                reqData, &len);
 199         hdr3 = (const struct eap_psk_hdr_3 *) pos;
 200         if (pos == NULL || len < sizeof(*hdr3)) {
 201                 wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
 202                            "length (%lu; expected %lu or more)",
 203                            (unsigned long) len,
 204                            (unsigned long) sizeof(*hdr3));
 205                 ret->ignore = TRUE;
 206                 return NULL;
 207         }
 208         left = len - sizeof(*hdr3);
 209         pchannel = (const u8 *) (hdr3 + 1);
 210         wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
 211         if (EAP_PSK_FLAGS_GET_T(hdr3->flags) != 2) {
 212                 wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
 213                            EAP_PSK_FLAGS_GET_T(hdr3->flags));
 214                 ret->methodState = METHOD_DONE;
 215                 ret->decision = DECISION_FAIL;
 216                 return NULL;
 217         }
 218         wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
 219                     EAP_PSK_RAND_LEN);
 220         wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
 221         wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
 222
 223         if (left < 4 + 16 + 1) {
 224                 wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
 225                            "third message (len=%lu, expected 21)",
 226                            (unsigned long) left);
 227                 ret->ignore = TRUE;
 228                 return NULL;
 229         }
 230
 231         /* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
 232         buflen = data->id_s_len + EAP_PSK_RAND_LEN;
 233         buf = os_malloc(buflen);
 234         if (buf == NULL)
 235                 return NULL;
 236         os_memcpy(buf, data->id_s, data->id_s_len);
 237         os_memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
 238         if (omac1_aes_128(data->ak, buf, buflen, mac)) {
 239                 os_free(buf);
 240                 return NULL;
 241         }
 242         os_free(buf);
 243         if (os_memcmp(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
 244                 wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
 245                            "message");
 246                 ret->methodState = METHOD_DONE;
 247                 ret->decision = DECISION_FAIL;
 248                 return NULL;
 249         }
 250         wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
 251
 252         if (eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
 253                                 data->msk, data->emsk)) {
 254                 ret->methodState = METHOD_DONE;
 255                 ret->decision = DECISION_FAIL;
 256                 return NULL;
 257         }
 258         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
 259         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->msk, EAP_MSK_LEN);
 260         wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: EMSK", data->emsk, EAP_EMSK_LEN);
 261
 262         os_memset(nonce, 0, 12);
 263         os_memcpy(nonce + 12, pchannel, 4);
 264         pchannel += 4;
 265         left -= 4;
 266
 267         tag = pchannel;
 268         pchannel += 16;
 269         left -= 16;
 270
 271         msg = pchannel;
 272
 273         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
 274                     nonce, sizeof(nonce));
 275         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr",
 276                     wpabuf_head(reqData), 5);
 277         wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
 278
 279         decrypted = os_malloc(left);
 280         if (decrypted == NULL) {
 281                 ret->methodState = METHOD_DONE;
 282                 ret->decision = DECISION_FAIL;
 283                 return NULL;
 284         }
 285         os_memcpy(decrypted, msg, left);
 286
 287         if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
 288                                 wpabuf_head(reqData),
 289                                 sizeof(struct eap_hdr) + 1 +
 290                                 sizeof(*hdr3) - EAP_PSK_MAC_LEN, decrypted,
 291                                 left, tag)) {
 292                 wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
 293                 os_free(decrypted);
 294                 return NULL;
 295         }
 296         wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
 297                     decrypted, left);
 298
 299         /* Verify R flag */
 300         switch (decrypted[0] >> 6) {
 301         case EAP_PSK_R_FLAG_CONT:
 302                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
 303                 failed = 1;
 304                 break;
 305         case EAP_PSK_R_FLAG_DONE_SUCCESS:
 306                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
 307                 break;
 308         case EAP_PSK_R_FLAG_DONE_FAILURE:
 309                 wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
 310                 wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
 311                            "authentication");
 312                 failed = 1;
 313                 break;
 314         }
 315
 316         data_len = 1;
 317         if ((decrypted[0] & EAP_PSK_E_FLAG) && left > 1)
 318                 data_len++;
 319         plen = sizeof(*hdr4) + 4 + 16 + data_len;
 320         resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PSK, plen,
 321                              EAP_CODE_RESPONSE, eap_get_id(reqData));
 322         if (resp == NULL) {
 323                 os_free(decrypted);
 324                 return NULL;
 325         }
 326         hdr4 = wpabuf_put(resp, sizeof(*hdr4));
 327         hdr4->flags = EAP_PSK_FLAGS_SET_T(3); /* T=3 */
 328         os_memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
 329         rpchannel = wpabuf_put(resp, 4 + 16 + data_len);
 330
 331         /* nonce++ */
 332         inc_byte_array(nonce, sizeof(nonce));
 333         os_memcpy(rpchannel, nonce + 12, 4);
 334
 335         if (decrypted[0] & EAP_PSK_E_FLAG) {
 336                 wpa_printf(MSG_DEBUG, "EAP-PSK: Unsupported E (Ext) flag");
 337                 failed = 1;
 338                 rpchannel[4 + 16] = (EAP_PSK_R_FLAG_DONE_FAILURE << 6) |
 339                         EAP_PSK_E_FLAG;
 340                 if (left > 1) {
 341                         /* Add empty EXT_Payload with same EXT_Type */
 342                         rpchannel[4 + 16 + 1] = decrypted[1];
 343                 }
 344         } else if (failed)
 345                 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_FAILURE << 6;
 346         else
 347                 rpchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
 348
 349         wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
 350                     rpchannel + 4 + 16, data_len);
 351         if (aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce),
 352                                 wpabuf_head(resp),
 353                                 sizeof(struct eap_hdr) + 1 + sizeof(*hdr4),
 354                                 rpchannel + 4 + 16, data_len, rpchannel + 4)) {
 355                 os_free(decrypted);
 356                 wpabuf_free(resp);
 357                 return NULL;
 358         }
 359         wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
 360                     rpchannel, 4 + 16 + data_len);
 361
 362         wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
 363                    failed ? "un" : "");
 364         data->state = PSK_DONE;
 365         ret->methodState = METHOD_DONE;
 366         ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
 367
 368         os_free(decrypted);
 369
 370         return resp;
 371 }
 372
 373
 374 static struct wpabuf * eap_psk_process(struct eap_sm *sm, void *priv,
 375                                        struct eap_method_ret *ret,
 376                                        const struct wpabuf *reqData)
 377 {
 378         struct eap_psk_data *data = priv;
 379         const u8 *pos;
 380         struct wpabuf *resp = NULL;
 381         size_t len;
 382
 383         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PSK, reqData, &len);
 384         if (pos == NULL) {
 385                 ret->ignore = TRUE;
 386                 return NULL;
 387         }
 388
 389         ret->ignore = FALSE;
 390         ret->methodState = METHOD_MAY_CONT;
 391         ret->decision = DECISION_FAIL;
 392         ret->allowNotifications = TRUE;
 393
 394         switch (data->state) {
 395         case PSK_INIT:
 396                 resp = eap_psk_process_1(data, ret, reqData);
 397                 break;
 398         case PSK_MAC_SENT:
 399                 resp = eap_psk_process_3(data, ret, reqData);
 400                 break;
 401         case PSK_DONE:
 402                 wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
 403                            "unexpected message");
 404                 ret->ignore = TRUE;
 405                 return NULL;
 406         }
 407
 408         if (ret->methodState == METHOD_DONE) {
 409                 ret->allowNotifications = FALSE;
 410         }
 411
 412         return resp;
 413 }
 414
 415
 416 static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
 417 {
 418         struct eap_psk_data *data = priv;
 419         return data->state == PSK_DONE;
 420 }
 421
 422
 423 static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
 424 {
 425         struct eap_psk_data *data = priv;
 426         u8 *key;
 427
 428         if (data->state != PSK_DONE)
 429                 return NULL;
 430
 431         key = os_malloc(EAP_MSK_LEN);
 432         if (key == NULL)
 433                 return NULL;
 434
 435         *len = EAP_MSK_LEN;
 436         os_memcpy(key, data->msk, EAP_MSK_LEN);
 437
 438         return key;
 439 }
 440
 441
 442 static u8 * eap_psk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 443 {
 444         struct eap_psk_data *data = priv;
 445         u8 *key;
 446
 447         if (data->state != PSK_DONE)
 448                 return NULL;
 449
 450         key = os_malloc(EAP_EMSK_LEN);
 451         if (key == NULL)
 452                 return NULL;
 453
 454         *len = EAP_EMSK_LEN;
 455         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
 456
 457         return key;
 458 }
 459
 460
 461 int eap_peer_psk_register(void)
 462 {
 463         struct eap_method *eap;
 464         int ret;
 465
 466         eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
 467                                     EAP_VENDOR_IETF, EAP_TYPE_PSK, "PSK");
 468         if (eap == NULL)
 469                 return -1;
 470
 471         eap->init = eap_psk_init;
 472         eap->deinit = eap_psk_deinit;
 473         eap->process = eap_psk_process;
 474         eap->isKeyAvailable = eap_psk_isKeyAvailable;
 475         eap->getKey = eap_psk_getKey;
 476         eap->get_emsk = eap_psk_get_emsk;
 477
 478         ret = eap_peer_method_register(eap);
 479         if (ret)
 480                 eap_peer_method_free(eap);
 481         return ret;
 482 }