src/eap_server/eap_sake.c

   1 /*
   2  * hostapd / EAP-SAKE (RFC 4763) server
   3  * Copyright (c) 2006-2007, 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
  15 #include "includes.h"
  16
  17 #include "common.h"
  18 #include "eap_server/eap_i.h"
  19 #include "eap_common/eap_sake_common.h"
  20
  21
  22 struct eap_sake_data {
  23         enum { IDENTITY, CHALLENGE, CONFIRM, SUCCESS, FAILURE } state;
  24         u8 rand_s[EAP_SAKE_RAND_LEN];
  25         u8 rand_p[EAP_SAKE_RAND_LEN];
  26         struct {
  27                 u8 auth[EAP_SAKE_TEK_AUTH_LEN];
  28                 u8 cipher[EAP_SAKE_TEK_CIPHER_LEN];
  29         } tek;
  30         u8 msk[EAP_MSK_LEN];
  31         u8 emsk[EAP_EMSK_LEN];
  32         u8 session_id;
  33         u8 *peerid;
  34         size_t peerid_len;
  35         u8 *serverid;
  36         size_t serverid_len;
  37 };
  38
  39
  40 static const char * eap_sake_state_txt(int state)
  41 {
  42         switch (state) {
  43         case IDENTITY:
  44                 return "IDENTITY";
  45         case CHALLENGE:
  46                 return "CHALLENGE";
  47         case CONFIRM:
  48                 return "CONFIRM";
  49         case SUCCESS:
  50                 return "SUCCESS";
  51         case FAILURE:
  52                 return "FAILURE";
  53         default:
  54                 return "?";
  55         }
  56 }
  57
  58
  59 static void eap_sake_state(struct eap_sake_data *data, int state)
  60 {
  61         wpa_printf(MSG_DEBUG, "EAP-SAKE: %s -> %s",
  62                    eap_sake_state_txt(data->state),
  63                    eap_sake_state_txt(state));
  64         data->state = state;
  65 }
  66
  67
  68 static void * eap_sake_init(struct eap_sm *sm)
  69 {
  70         struct eap_sake_data *data;
  71
  72         data = os_zalloc(sizeof(*data));
  73         if (data == NULL)
  74                 return NULL;
  75         data->state = CHALLENGE;
  76
  77         if (os_get_random(&data->session_id, 1)) {
  78                 wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to get random data");
  79                 os_free(data);
  80                 return NULL;
  81         }
  82         wpa_printf(MSG_DEBUG, "EAP-SAKE: Initialized Session ID %d",
  83                    data->session_id);
  84
  85         /* TODO: add support for configuring SERVERID */
  86         data->serverid = (u8 *) os_strdup("hostapd");
  87         if (data->serverid)
  88                 data->serverid_len = os_strlen((char *) data->serverid);
  89
  90         return data;
  91 }
  92
  93
  94 static void eap_sake_reset(struct eap_sm *sm, void *priv)
  95 {
  96         struct eap_sake_data *data = priv;
  97         os_free(data->serverid);
  98         os_free(data->peerid);
  99         os_free(data);
 100 }
 101
 102
 103 static struct wpabuf * eap_sake_build_msg(struct eap_sake_data *data,
 104                                           u8 id, size_t length, u8 subtype)
 105 {
 106         struct eap_sake_hdr *sake;
 107         struct wpabuf *msg;
 108         size_t plen;
 109
 110         plen = sizeof(struct eap_sake_hdr) + length;
 111
 112         msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_SAKE, plen,
 113                             EAP_CODE_REQUEST, id);
 114         if (msg == NULL) {
 115                 wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to allocate memory "
 116                            "request");
 117                 return NULL;
 118         }
 119
 120         sake = wpabuf_put(msg, sizeof(*sake));
 121         sake->version = EAP_SAKE_VERSION;
 122         sake->session_id = data->session_id;
 123         sake->subtype = subtype;
 124
 125         return msg;
 126 }
 127
 128
 129 static struct wpabuf * eap_sake_build_identity(struct eap_sm *sm,
 130                                                struct eap_sake_data *data,
 131                                                u8 id)
 132 {
 133         struct wpabuf *msg;
 134         size_t plen;
 135
 136         wpa_printf(MSG_DEBUG, "EAP-SAKE: Request/Identity");
 137
 138         plen = 4;
 139         if (data->serverid)
 140                 plen += 2 + data->serverid_len;
 141         msg = eap_sake_build_msg(data, id, plen, EAP_SAKE_SUBTYPE_IDENTITY);
 142         if (msg == NULL) {
 143                 data->state = FAILURE;
 144                 return NULL;
 145         }
 146
 147         wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_PERM_ID_REQ");
 148         eap_sake_add_attr(msg, EAP_SAKE_AT_PERM_ID_REQ, NULL, 2);
 149
 150         if (data->serverid) {
 151                 wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_SERVERID");
 152                 eap_sake_add_attr(msg, EAP_SAKE_AT_SERVERID,
 153                                   data->serverid, data->serverid_len);
 154         }
 155
 156         return msg;
 157 }
 158
 159
 160 static struct wpabuf * eap_sake_build_challenge(struct eap_sm *sm,
 161                                                 struct eap_sake_data *data,
 162                                                 u8 id)
 163 {
 164         struct wpabuf *msg;
 165         size_t plen;
 166
 167         wpa_printf(MSG_DEBUG, "EAP-SAKE: Request/Challenge");
 168
 169         if (os_get_random(data->rand_s, EAP_SAKE_RAND_LEN)) {
 170                 wpa_printf(MSG_ERROR, "EAP-SAKE: Failed to get random data");
 171                 data->state = FAILURE;
 172                 return NULL;
 173         }
 174         wpa_hexdump(MSG_MSGDUMP, "EAP-SAKE: RAND_S (server rand)",
 175                     data->rand_s, EAP_SAKE_RAND_LEN);
 176
 177         plen = 2 + EAP_SAKE_RAND_LEN;
 178         if (data->serverid)
 179                 plen += 2 + data->serverid_len;
 180         msg = eap_sake_build_msg(data, id, plen, EAP_SAKE_SUBTYPE_CHALLENGE);
 181         if (msg == NULL) {
 182                 data->state = FAILURE;
 183                 return NULL;
 184         }
 185
 186         wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_RAND_S");
 187         eap_sake_add_attr(msg, EAP_SAKE_AT_RAND_S,
 188                           data->rand_s, EAP_SAKE_RAND_LEN);
 189
 190         if (data->serverid) {
 191                 wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_SERVERID");
 192                 eap_sake_add_attr(msg, EAP_SAKE_AT_SERVERID,
 193                                   data->serverid, data->serverid_len);
 194         }
 195
 196         return msg;
 197 }
 198
 199
 200 static struct wpabuf * eap_sake_build_confirm(struct eap_sm *sm,
 201                                               struct eap_sake_data *data,
 202                                               u8 id)
 203 {
 204         struct wpabuf *msg;
 205         u8 *mic;
 206
 207         wpa_printf(MSG_DEBUG, "EAP-SAKE: Request/Confirm");
 208
 209         msg = eap_sake_build_msg(data, id, 2 + EAP_SAKE_MIC_LEN,
 210                                  EAP_SAKE_SUBTYPE_CONFIRM);
 211         if (msg == NULL) {
 212                 data->state = FAILURE;
 213                 return NULL;
 214         }
 215
 216         wpa_printf(MSG_DEBUG, "EAP-SAKE: * AT_MIC_S");
 217         wpabuf_put_u8(msg, EAP_SAKE_AT_MIC_S);
 218         wpabuf_put_u8(msg, 2 + EAP_SAKE_MIC_LEN);
 219         mic = wpabuf_put(msg, EAP_SAKE_MIC_LEN);
 220         if (eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
 221                                  data->serverid, data->serverid_len,
 222                                  data->peerid, data->peerid_len, 0,
 223                                  wpabuf_head(msg), wpabuf_len(msg), mic, mic))
 224         {
 225                 wpa_printf(MSG_INFO, "EAP-SAKE: Failed to compute MIC");
 226                 data->state = FAILURE;
 227                 os_free(msg);
 228                 return NULL;
 229         }
 230
 231         return msg;
 232 }
 233
 234
 235 static struct wpabuf * eap_sake_buildReq(struct eap_sm *sm, void *priv, u8 id)
 236 {
 237         struct eap_sake_data *data = priv;
 238
 239         switch (data->state) {
 240         case IDENTITY:
 241                 return eap_sake_build_identity(sm, data, id);
 242         case CHALLENGE:
 243                 return eap_sake_build_challenge(sm, data, id);
 244         case CONFIRM:
 245                 return eap_sake_build_confirm(sm, data, id);
 246         default:
 247                 wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown state %d in buildReq",
 248                            data->state);
 249                 break;
 250         }
 251         return NULL;
 252 }
 253
 254
 255 static Boolean eap_sake_check(struct eap_sm *sm, void *priv,
 256                               struct wpabuf *respData)
 257 {
 258         struct eap_sake_data *data = priv;
 259         struct eap_sake_hdr *resp;
 260         size_t len;
 261         u8 version, session_id, subtype;
 262         const u8 *pos;
 263
 264         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_SAKE, respData, &len);
 265         if (pos == NULL || len < sizeof(struct eap_sake_hdr)) {
 266                 wpa_printf(MSG_INFO, "EAP-SAKE: Invalid frame");
 267                 return TRUE;
 268         }
 269
 270         resp = (struct eap_sake_hdr *) pos;
 271         version = resp->version;
 272         session_id = resp->session_id;
 273         subtype = resp->subtype;
 274
 275         if (version != EAP_SAKE_VERSION) {
 276                 wpa_printf(MSG_INFO, "EAP-SAKE: Unknown version %d", version);
 277                 return TRUE;
 278         }
 279
 280         if (session_id != data->session_id) {
 281                 wpa_printf(MSG_INFO, "EAP-SAKE: Session ID mismatch (%d,%d)",
 282                            session_id, data->session_id);
 283                 return TRUE;
 284         }
 285
 286         wpa_printf(MSG_DEBUG, "EAP-SAKE: Received frame: subtype=%d", subtype);
 287
 288         if (data->state == IDENTITY && subtype == EAP_SAKE_SUBTYPE_IDENTITY)
 289                 return FALSE;
 290
 291         if (data->state == CHALLENGE && subtype == EAP_SAKE_SUBTYPE_CHALLENGE)
 292                 return FALSE;
 293
 294         if (data->state == CONFIRM && subtype == EAP_SAKE_SUBTYPE_CONFIRM)
 295                 return FALSE;
 296
 297         if (subtype == EAP_SAKE_SUBTYPE_AUTH_REJECT)
 298                 return FALSE;
 299
 300         wpa_printf(MSG_INFO, "EAP-SAKE: Unexpected subtype=%d in state=%d",
 301                    subtype, data->state);
 302
 303         return TRUE;
 304 }
 305
 306
 307 static void eap_sake_process_identity(struct eap_sm *sm,
 308                                       struct eap_sake_data *data,
 309                                       const struct wpabuf *respData,
 310                                       const u8 *payload, size_t payloadlen)
 311 {
 312         if (data->state != IDENTITY)
 313                 return;
 314
 315         wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Response/Identity");
 316         /* TODO: update identity and select new user data */
 317         eap_sake_state(data, CHALLENGE);
 318 }
 319
 320
 321 static void eap_sake_process_challenge(struct eap_sm *sm,
 322                                        struct eap_sake_data *data,
 323                                        const struct wpabuf *respData,
 324                                        const u8 *payload, size_t payloadlen)
 325 {
 326         struct eap_sake_parse_attr attr;
 327         u8 mic_p[EAP_SAKE_MIC_LEN];
 328
 329         if (data->state != CHALLENGE)
 330                 return;
 331
 332         wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Response/Challenge");
 333
 334         if (eap_sake_parse_attributes(payload, payloadlen, &attr))
 335                 return;
 336
 337         if (!attr.rand_p || !attr.mic_p) {
 338                 wpa_printf(MSG_INFO, "EAP-SAKE: Response/Challenge did not "
 339                            "include AT_RAND_P or AT_MIC_P");
 340                 return;
 341         }
 342
 343         os_memcpy(data->rand_p, attr.rand_p, EAP_SAKE_RAND_LEN);
 344
 345         os_free(data->peerid);
 346         data->peerid = NULL;
 347         data->peerid_len = 0;
 348         if (attr.peerid) {
 349                 data->peerid = os_malloc(attr.peerid_len);
 350                 if (data->peerid == NULL)
 351                         return;
 352                 os_memcpy(data->peerid, attr.peerid, attr.peerid_len);
 353                 data->peerid_len = attr.peerid_len;
 354         }
 355
 356         if (sm->user == NULL || sm->user->password == NULL ||
 357             sm->user->password_len != 2 * EAP_SAKE_ROOT_SECRET_LEN) {
 358                 wpa_printf(MSG_INFO, "EAP-SAKE: Plaintext password with "
 359                            "%d-byte key not configured",
 360                            2 * EAP_SAKE_ROOT_SECRET_LEN);
 361                 data->state = FAILURE;
 362                 return;
 363         }
 364         eap_sake_derive_keys(sm->user->password,
 365                              sm->user->password + EAP_SAKE_ROOT_SECRET_LEN,
 366                              data->rand_s, data->rand_p,
 367                              (u8 *) &data->tek, data->msk, data->emsk);
 368
 369         eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
 370                              data->serverid, data->serverid_len,
 371                              data->peerid, data->peerid_len, 1,
 372                              wpabuf_head(respData), wpabuf_len(respData),
 373                              attr.mic_p, mic_p);
 374         if (os_memcmp(attr.mic_p, mic_p, EAP_SAKE_MIC_LEN) != 0) {
 375                 wpa_printf(MSG_INFO, "EAP-SAKE: Incorrect AT_MIC_P");
 376                 eap_sake_state(data, FAILURE);
 377                 return;
 378         }
 379
 380         eap_sake_state(data, CONFIRM);
 381 }
 382
 383
 384 static void eap_sake_process_confirm(struct eap_sm *sm,
 385                                      struct eap_sake_data *data,
 386                                      const struct wpabuf *respData,
 387                                      const u8 *payload, size_t payloadlen)
 388 {
 389         struct eap_sake_parse_attr attr;
 390         u8 mic_p[EAP_SAKE_MIC_LEN];
 391
 392         if (data->state != CONFIRM)
 393                 return;
 394
 395         wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Response/Confirm");
 396
 397         if (eap_sake_parse_attributes(payload, payloadlen, &attr))
 398                 return;
 399
 400         if (!attr.mic_p) {
 401                 wpa_printf(MSG_INFO, "EAP-SAKE: Response/Confirm did not "
 402                            "include AT_MIC_P");
 403                 return;
 404         }
 405
 406         eap_sake_compute_mic(data->tek.auth, data->rand_s, data->rand_p,
 407                              data->serverid, data->serverid_len,
 408                              data->peerid, data->peerid_len, 1,
 409                              wpabuf_head(respData), wpabuf_len(respData),
 410                              attr.mic_p, mic_p);
 411         if (os_memcmp(attr.mic_p, mic_p, EAP_SAKE_MIC_LEN) != 0) {
 412                 wpa_printf(MSG_INFO, "EAP-SAKE: Incorrect AT_MIC_P");
 413                 eap_sake_state(data, FAILURE);
 414         } else
 415                 eap_sake_state(data, SUCCESS);
 416 }
 417
 418
 419 static void eap_sake_process_auth_reject(struct eap_sm *sm,
 420                                          struct eap_sake_data *data,
 421                                          const struct wpabuf *respData,
 422                                          const u8 *payload, size_t payloadlen)
 423 {
 424         wpa_printf(MSG_DEBUG, "EAP-SAKE: Received Response/Auth-Reject");
 425         eap_sake_state(data, FAILURE);
 426 }
 427
 428
 429 static void eap_sake_process(struct eap_sm *sm, void *priv,
 430                              struct wpabuf *respData)
 431 {
 432         struct eap_sake_data *data = priv;
 433         struct eap_sake_hdr *resp;
 434         u8 subtype;
 435         size_t len;
 436         const u8 *pos, *end;
 437
 438         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_SAKE, respData, &len);
 439         if (pos == NULL || len < sizeof(struct eap_sake_hdr))
 440                 return;
 441
 442         resp = (struct eap_sake_hdr *) pos;
 443         end = pos + len;
 444         subtype = resp->subtype;
 445         pos = (u8 *) (resp + 1);
 446
 447         wpa_hexdump(MSG_DEBUG, "EAP-SAKE: Received attributes",
 448                     pos, end - pos);
 449
 450         switch (subtype) {
 451         case EAP_SAKE_SUBTYPE_IDENTITY:
 452                 eap_sake_process_identity(sm, data, respData, pos, end - pos);
 453                 break;
 454         case EAP_SAKE_SUBTYPE_CHALLENGE:
 455                 eap_sake_process_challenge(sm, data, respData, pos, end - pos);
 456                 break;
 457         case EAP_SAKE_SUBTYPE_CONFIRM:
 458                 eap_sake_process_confirm(sm, data, respData, pos, end - pos);
 459                 break;
 460         case EAP_SAKE_SUBTYPE_AUTH_REJECT:
 461                 eap_sake_process_auth_reject(sm, data, respData, pos,
 462                                              end - pos);
 463                 break;
 464         }
 465 }
 466
 467
 468 static Boolean eap_sake_isDone(struct eap_sm *sm, void *priv)
 469 {
 470         struct eap_sake_data *data = priv;
 471         return data->state == SUCCESS || data->state == FAILURE;
 472 }
 473
 474
 475 static u8 * eap_sake_getKey(struct eap_sm *sm, void *priv, size_t *len)
 476 {
 477         struct eap_sake_data *data = priv;
 478         u8 *key;
 479
 480         if (data->state != SUCCESS)
 481                 return NULL;
 482
 483         key = os_malloc(EAP_MSK_LEN);
 484         if (key == NULL)
 485                 return NULL;
 486         os_memcpy(key, data->msk, EAP_MSK_LEN);
 487         *len = EAP_MSK_LEN;
 488
 489         return key;
 490 }
 491
 492
 493 static u8 * eap_sake_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 494 {
 495         struct eap_sake_data *data = priv;
 496         u8 *key;
 497
 498         if (data->state != SUCCESS)
 499                 return NULL;
 500
 501         key = os_malloc(EAP_EMSK_LEN);
 502         if (key == NULL)
 503                 return NULL;
 504         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
 505         *len = EAP_EMSK_LEN;
 506
 507         return key;
 508 }
 509
 510
 511 static Boolean eap_sake_isSuccess(struct eap_sm *sm, void *priv)
 512 {
 513         struct eap_sake_data *data = priv;
 514         return data->state == SUCCESS;
 515 }
 516
 517
 518 int eap_server_sake_register(void)
 519 {
 520         struct eap_method *eap;
 521         int ret;
 522
 523         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
 524                                       EAP_VENDOR_IETF, EAP_TYPE_SAKE, "SAKE");
 525         if (eap == NULL)
 526                 return -1;
 527
 528         eap->init = eap_sake_init;
 529         eap->reset = eap_sake_reset;
 530         eap->buildReq = eap_sake_buildReq;
 531         eap->check = eap_sake_check;
 532         eap->process = eap_sake_process;
 533         eap->isDone = eap_sake_isDone;
 534         eap->getKey = eap_sake_getKey;
 535         eap->isSuccess = eap_sake_isSuccess;
 536         eap->get_emsk = eap_sake_get_emsk;
 537
 538         ret = eap_server_method_register(eap);
 539         if (ret)
 540                 eap_server_method_free(eap);
 541         return ret;
 542 }