contrib/hostapd/src/eap_peer/eap_pax.c

   1 /*
   2  * EAP peer method: EAP-PAX (RFC 4746)
   3  * Copyright (c) 2005-2008, 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
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "crypto/random.h"
  13 #include "eap_common/eap_pax_common.h"
  14 #include "eap_i.h"
  15
  16 /*
  17  * Note: only PAX_STD subprotocol is currently supported
  18  *
  19  * TODO: Add support with PAX_SEC with the mandatory to implement ciphersuite
  20  * (HMAC_SHA1_128, IANA DH Group 14 (2048 bits), RSA-PKCS1-V1_5) and
  21  * recommended ciphersuite (HMAC_SHA256_128, IANA DH Group 15 (3072 bits),
  22  * RSAES-OAEP).
  23  */
  24
  25 struct eap_pax_data {
  26         enum { PAX_INIT, PAX_STD_2_SENT, PAX_DONE } state;
  27         u8 mac_id, dh_group_id, public_key_id;
  28         union {
  29                 u8 e[2 * EAP_PAX_RAND_LEN];
  30                 struct {
  31                         u8 x[EAP_PAX_RAND_LEN]; /* server rand */
  32                         u8 y[EAP_PAX_RAND_LEN]; /* client rand */
  33                 } r;
  34         } rand;
  35         char *cid;
  36         size_t cid_len;
  37         u8 ak[EAP_PAX_AK_LEN];
  38         u8 mk[EAP_PAX_MK_LEN];
  39         u8 ck[EAP_PAX_CK_LEN];
  40         u8 ick[EAP_PAX_ICK_LEN];
  41 };
  42
  43
  44 static void eap_pax_deinit(struct eap_sm *sm, void *priv);
  45
  46
  47 static void * eap_pax_init(struct eap_sm *sm)
  48 {
  49         struct eap_pax_data *data;
  50         const u8 *identity, *password;
  51         size_t identity_len, password_len;
  52
  53         identity = eap_get_config_identity(sm, &identity_len);
  54         password = eap_get_config_password(sm, &password_len);
  55         if (!identity || !password) {
  56                 wpa_printf(MSG_INFO, "EAP-PAX: CID (nai) or key (password) "
  57                            "not configured");
  58                 return NULL;
  59         }
  60
  61         if (password_len != EAP_PAX_AK_LEN) {
  62                 wpa_printf(MSG_INFO, "EAP-PAX: Invalid PSK length");
  63                 return NULL;
  64         }
  65
  66         data = os_zalloc(sizeof(*data));
  67         if (data == NULL)
  68                 return NULL;
  69         data->state = PAX_INIT;
  70
  71         data->cid = os_malloc(identity_len);
  72         if (data->cid == NULL) {
  73                 eap_pax_deinit(sm, data);
  74                 return NULL;
  75         }
  76         os_memcpy(data->cid, identity, identity_len);
  77         data->cid_len = identity_len;
  78
  79         os_memcpy(data->ak, password, EAP_PAX_AK_LEN);
  80
  81         return data;
  82 }
  83
  84
  85 static void eap_pax_deinit(struct eap_sm *sm, void *priv)
  86 {
  87         struct eap_pax_data *data = priv;
  88         os_free(data->cid);
  89         os_free(data);
  90 }
  91
  92
  93 static struct wpabuf * eap_pax_alloc_resp(const struct eap_pax_hdr *req,
  94                                           u8 id, u8 op_code, size_t plen)
  95 {
  96         struct wpabuf *resp;
  97         struct eap_pax_hdr *pax;
  98
  99         resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
 100                              sizeof(*pax) + plen, EAP_CODE_RESPONSE, id);
 101         if (resp == NULL)
 102                 return NULL;
 103
 104         pax = wpabuf_put(resp, sizeof(*pax));
 105         pax->op_code = op_code;
 106         pax->flags = 0;
 107         pax->mac_id = req->mac_id;
 108         pax->dh_group_id = req->dh_group_id;
 109         pax->public_key_id = req->public_key_id;
 110
 111         return resp;
 112 }
 113
 114
 115 static struct wpabuf * eap_pax_process_std_1(struct eap_pax_data *data,
 116                                              struct eap_method_ret *ret, u8 id,
 117                                              const struct eap_pax_hdr *req,
 118                                              size_t req_plen)
 119 {
 120         struct wpabuf *resp;
 121         const u8 *pos;
 122         u8 *rpos;
 123         size_t left, plen;
 124
 125         wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-1 (received)");
 126
 127         if (data->state != PAX_INIT) {
 128                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 received in "
 129                            "unexpected state (%d) - ignored", data->state);
 130                 ret->ignore = TRUE;
 131                 return NULL;
 132         }
 133
 134         if (req->flags & EAP_PAX_FLAGS_CE) {
 135                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with CE flag set - "
 136                            "ignored");
 137                 ret->ignore = TRUE;
 138                 return NULL;
 139         }
 140
 141         left = req_plen - sizeof(*req);
 142
 143         if (left < 2 + EAP_PAX_RAND_LEN) {
 144                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with too short "
 145                            "payload");
 146                 ret->ignore = TRUE;
 147                 return NULL;
 148         }
 149
 150         pos = (const u8 *) (req + 1);
 151         if (WPA_GET_BE16(pos) != EAP_PAX_RAND_LEN) {
 152                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-1 with incorrect A "
 153                            "length %d (expected %d)",
 154                            WPA_GET_BE16(pos), EAP_PAX_RAND_LEN);
 155                 ret->ignore = TRUE;
 156                 return NULL;
 157         }
 158
 159         pos += 2;
 160         left -= 2;
 161         os_memcpy(data->rand.r.x, pos, EAP_PAX_RAND_LEN);
 162         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: X (server rand)",
 163                     data->rand.r.x, EAP_PAX_RAND_LEN);
 164         pos += EAP_PAX_RAND_LEN;
 165         left -= EAP_PAX_RAND_LEN;
 166
 167         if (left > 0) {
 168                 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
 169                             pos, left);
 170         }
 171
 172         if (random_get_bytes(data->rand.r.y, EAP_PAX_RAND_LEN)) {
 173                 wpa_printf(MSG_ERROR, "EAP-PAX: Failed to get random data");
 174                 ret->ignore = TRUE;
 175                 return NULL;
 176         }
 177         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Y (client rand)",
 178                     data->rand.r.y, EAP_PAX_RAND_LEN);
 179
 180         if (eap_pax_initial_key_derivation(req->mac_id, data->ak, data->rand.e,
 181                                            data->mk, data->ck, data->ick) < 0)
 182         {
 183                 ret->ignore = TRUE;
 184                 return NULL;
 185         }
 186
 187         wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-2 (sending)");
 188
 189         plen = 2 + EAP_PAX_RAND_LEN + 2 + data->cid_len + 2 + EAP_PAX_MAC_LEN +
 190                 EAP_PAX_ICV_LEN;
 191         resp = eap_pax_alloc_resp(req, id, EAP_PAX_OP_STD_2, plen);
 192         if (resp == NULL)
 193                 return NULL;
 194
 195         wpabuf_put_be16(resp, EAP_PAX_RAND_LEN);
 196         wpabuf_put_data(resp, data->rand.r.y, EAP_PAX_RAND_LEN);
 197         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: B = Y (client rand)",
 198                     data->rand.r.y, EAP_PAX_RAND_LEN);
 199
 200         wpabuf_put_be16(resp, data->cid_len);
 201         wpabuf_put_data(resp, data->cid, data->cid_len);
 202         wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PAX: CID",
 203                           (u8 *) data->cid, data->cid_len);
 204
 205         wpabuf_put_be16(resp, EAP_PAX_MAC_LEN);
 206         rpos = wpabuf_put(resp, EAP_PAX_MAC_LEN);
 207         eap_pax_mac(req->mac_id, data->ck, EAP_PAX_CK_LEN,
 208                     data->rand.r.x, EAP_PAX_RAND_LEN,
 209                     data->rand.r.y, EAP_PAX_RAND_LEN,
 210                     (u8 *) data->cid, data->cid_len, rpos);
 211         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(A, B, CID)",
 212                     rpos, EAP_PAX_MAC_LEN);
 213
 214         /* Optional ADE could be added here, if needed */
 215
 216         rpos = wpabuf_put(resp, EAP_PAX_ICV_LEN);
 217         eap_pax_mac(req->mac_id, data->ick, EAP_PAX_ICK_LEN,
 218                     wpabuf_head(resp), wpabuf_len(resp) - EAP_PAX_ICV_LEN,
 219                     NULL, 0, NULL, 0, rpos);
 220         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", rpos, EAP_PAX_ICV_LEN);
 221
 222         data->state = PAX_STD_2_SENT;
 223         data->mac_id = req->mac_id;
 224         data->dh_group_id = req->dh_group_id;
 225         data->public_key_id = req->public_key_id;
 226
 227         return resp;
 228 }
 229
 230
 231 static struct wpabuf * eap_pax_process_std_3(struct eap_pax_data *data,
 232                                              struct eap_method_ret *ret, u8 id,
 233                                              const struct eap_pax_hdr *req,
 234                                              size_t req_plen)
 235 {
 236         struct wpabuf *resp;
 237         u8 *rpos, mac[EAP_PAX_MAC_LEN];
 238         const u8 *pos;
 239         size_t left;
 240
 241         wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-3 (received)");
 242
 243         if (data->state != PAX_STD_2_SENT) {
 244                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 received in "
 245                            "unexpected state (%d) - ignored", data->state);
 246                 ret->ignore = TRUE;
 247                 return NULL;
 248         }
 249
 250         if (req->flags & EAP_PAX_FLAGS_CE) {
 251                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with CE flag set - "
 252                            "ignored");
 253                 ret->ignore = TRUE;
 254                 return NULL;
 255         }
 256
 257         left = req_plen - sizeof(*req);
 258
 259         if (left < 2 + EAP_PAX_MAC_LEN) {
 260                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with too short "
 261                            "payload");
 262                 ret->ignore = TRUE;
 263                 return NULL;
 264         }
 265
 266         pos = (const u8 *) (req + 1);
 267         if (WPA_GET_BE16(pos) != EAP_PAX_MAC_LEN) {
 268                 wpa_printf(MSG_INFO, "EAP-PAX: PAX_STD-3 with incorrect "
 269                            "MAC_CK length %d (expected %d)",
 270                            WPA_GET_BE16(pos), EAP_PAX_MAC_LEN);
 271                 ret->ignore = TRUE;
 272                 return NULL;
 273         }
 274         pos += 2;
 275         left -= 2;
 276         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(B, CID)",
 277                     pos, EAP_PAX_MAC_LEN);
 278         eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
 279                     data->rand.r.y, EAP_PAX_RAND_LEN,
 280                     (u8 *) data->cid, data->cid_len, NULL, 0, mac);
 281         if (os_memcmp(pos, mac, EAP_PAX_MAC_LEN) != 0) {
 282                 wpa_printf(MSG_INFO, "EAP-PAX: Invalid MAC_CK(B, CID) "
 283                            "received");
 284                 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected MAC_CK(B, CID)",
 285                             mac, EAP_PAX_MAC_LEN);
 286                 ret->methodState = METHOD_DONE;
 287                 ret->decision = DECISION_FAIL;
 288                 return NULL;
 289         }
 290
 291         pos += EAP_PAX_MAC_LEN;
 292         left -= EAP_PAX_MAC_LEN;
 293
 294         if (left > 0) {
 295                 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
 296                             pos, left);
 297         }
 298
 299         wpa_printf(MSG_DEBUG, "EAP-PAX: PAX-ACK (sending)");
 300
 301         resp = eap_pax_alloc_resp(req, id, EAP_PAX_OP_ACK, EAP_PAX_ICV_LEN);
 302         if (resp == NULL)
 303                 return NULL;
 304
 305         /* Optional ADE could be added here, if needed */
 306
 307         rpos = wpabuf_put(resp, EAP_PAX_ICV_LEN);
 308         eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
 309                     wpabuf_head(resp), wpabuf_len(resp) - EAP_PAX_ICV_LEN,
 310                     NULL, 0, NULL, 0, rpos);
 311         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", rpos, EAP_PAX_ICV_LEN);
 312
 313         data->state = PAX_DONE;
 314         ret->methodState = METHOD_DONE;
 315         ret->decision = DECISION_UNCOND_SUCC;
 316         ret->allowNotifications = FALSE;
 317
 318         return resp;
 319 }
 320
 321
 322 static struct wpabuf * eap_pax_process(struct eap_sm *sm, void *priv,
 323                                        struct eap_method_ret *ret,
 324                                        const struct wpabuf *reqData)
 325 {
 326         struct eap_pax_data *data = priv;
 327         const struct eap_pax_hdr *req;
 328         struct wpabuf *resp;
 329         u8 icvbuf[EAP_PAX_ICV_LEN], id;
 330         const u8 *icv, *pos;
 331         size_t len;
 332         u16 flen, mlen;
 333
 334         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, reqData, &len);
 335         if (pos == NULL || len < EAP_PAX_ICV_LEN) {
 336                 ret->ignore = TRUE;
 337                 return NULL;
 338         }
 339         id = eap_get_id(reqData);
 340         req = (const struct eap_pax_hdr *) pos;
 341         flen = len - EAP_PAX_ICV_LEN;
 342         mlen = wpabuf_len(reqData) - EAP_PAX_ICV_LEN;
 343
 344         wpa_printf(MSG_DEBUG, "EAP-PAX: received frame: op_code 0x%x "
 345                    "flags 0x%x mac_id 0x%x dh_group_id 0x%x "
 346                    "public_key_id 0x%x",
 347                    req->op_code, req->flags, req->mac_id, req->dh_group_id,
 348                    req->public_key_id);
 349         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: received payload",
 350                     pos, len - EAP_PAX_ICV_LEN);
 351
 352         if (data->state != PAX_INIT && data->mac_id != req->mac_id) {
 353                 wpa_printf(MSG_INFO, "EAP-PAX: MAC ID changed during "
 354                            "authentication (was 0x%d, is 0x%d)",
 355                            data->mac_id, req->mac_id);
 356                 ret->ignore = TRUE;
 357                 return NULL;
 358         }
 359
 360         if (data->state != PAX_INIT && data->dh_group_id != req->dh_group_id) {
 361                 wpa_printf(MSG_INFO, "EAP-PAX: DH Group ID changed during "
 362                            "authentication (was 0x%d, is 0x%d)",
 363                            data->dh_group_id, req->dh_group_id);
 364                 ret->ignore = TRUE;
 365                 return NULL;
 366         }
 367
 368         if (data->state != PAX_INIT &&
 369             data->public_key_id != req->public_key_id) {
 370                 wpa_printf(MSG_INFO, "EAP-PAX: Public Key ID changed during "
 371                            "authentication (was 0x%d, is 0x%d)",
 372                            data->public_key_id, req->public_key_id);
 373                 ret->ignore = TRUE;
 374                 return NULL;
 375         }
 376
 377         /* TODO: add support EAP_PAX_HMAC_SHA256_128 */
 378         if (req->mac_id != EAP_PAX_MAC_HMAC_SHA1_128) {
 379                 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported MAC ID 0x%x",
 380                            req->mac_id);
 381                 ret->ignore = TRUE;
 382                 return NULL;
 383         }
 384
 385         if (req->dh_group_id != EAP_PAX_DH_GROUP_NONE) {
 386                 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported DH Group ID 0x%x",
 387                            req->dh_group_id);
 388                 ret->ignore = TRUE;
 389                 return NULL;
 390         }
 391
 392         if (req->public_key_id != EAP_PAX_PUBLIC_KEY_NONE) {
 393                 wpa_printf(MSG_INFO, "EAP-PAX: Unsupported Public Key ID 0x%x",
 394                            req->public_key_id);
 395                 ret->ignore = TRUE;
 396                 return NULL;
 397         }
 398
 399         if (req->flags & EAP_PAX_FLAGS_MF) {
 400                 /* TODO: add support for reassembling fragments */
 401                 wpa_printf(MSG_INFO, "EAP-PAX: fragmentation not supported - "
 402                            "ignored packet");
 403                 ret->ignore = TRUE;
 404                 return NULL;
 405         }
 406
 407         icv = pos + len - EAP_PAX_ICV_LEN;
 408         wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", icv, EAP_PAX_ICV_LEN);
 409         if (req->op_code == EAP_PAX_OP_STD_1) {
 410                 eap_pax_mac(req->mac_id, (u8 *) "", 0,
 411                             wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
 412                             icvbuf);
 413         } else {
 414                 eap_pax_mac(req->mac_id, data->ick, EAP_PAX_ICK_LEN,
 415                             wpabuf_head(reqData), mlen, NULL, 0, NULL, 0,
 416                             icvbuf);
 417         }
 418         if (os_memcmp(icv, icvbuf, EAP_PAX_ICV_LEN) != 0) {
 419                 wpa_printf(MSG_DEBUG, "EAP-PAX: invalid ICV - ignoring the "
 420                            "message");
 421                 wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: expected ICV",
 422                             icvbuf, EAP_PAX_ICV_LEN);
 423                 ret->ignore = TRUE;
 424                 return NULL;
 425         }
 426
 427         ret->ignore = FALSE;
 428         ret->methodState = METHOD_MAY_CONT;
 429         ret->decision = DECISION_FAIL;
 430         ret->allowNotifications = TRUE;
 431
 432         switch (req->op_code) {
 433         case EAP_PAX_OP_STD_1:
 434                 resp = eap_pax_process_std_1(data, ret, id, req, flen);
 435                 break;
 436         case EAP_PAX_OP_STD_3:
 437                 resp = eap_pax_process_std_3(data, ret, id, req, flen);
 438                 break;
 439         default:
 440                 wpa_printf(MSG_DEBUG, "EAP-PAX: ignoring message with unknown "
 441                            "op_code %d", req->op_code);
 442                 ret->ignore = TRUE;
 443                 return NULL;
 444         }
 445
 446         if (ret->methodState == METHOD_DONE) {
 447                 ret->allowNotifications = FALSE;
 448         }
 449
 450         return resp;
 451 }
 452
 453
 454 static Boolean eap_pax_isKeyAvailable(struct eap_sm *sm, void *priv)
 455 {
 456         struct eap_pax_data *data = priv;
 457         return data->state == PAX_DONE;
 458 }
 459
 460
 461 static u8 * eap_pax_getKey(struct eap_sm *sm, void *priv, size_t *len)
 462 {
 463         struct eap_pax_data *data = priv;
 464         u8 *key;
 465
 466         if (data->state != PAX_DONE)
 467                 return NULL;
 468
 469         key = os_malloc(EAP_MSK_LEN);
 470         if (key == NULL)
 471                 return NULL;
 472
 473         *len = EAP_MSK_LEN;
 474         eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
 475                     "Master Session Key", data->rand.e, 2 * EAP_PAX_RAND_LEN,
 476                     EAP_MSK_LEN, key);
 477
 478         return key;
 479 }
 480
 481
 482 static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 483 {
 484         struct eap_pax_data *data = priv;
 485         u8 *key;
 486
 487         if (data->state != PAX_DONE)
 488                 return NULL;
 489
 490         key = os_malloc(EAP_EMSK_LEN);
 491         if (key == NULL)
 492                 return NULL;
 493
 494         *len = EAP_EMSK_LEN;
 495         eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
 496                     "Extended Master Session Key",
 497                     data->rand.e, 2 * EAP_PAX_RAND_LEN,
 498                     EAP_EMSK_LEN, key);
 499
 500         return key;
 501 }
 502
 503
 504 int eap_peer_pax_register(void)
 505 {
 506         struct eap_method *eap;
 507         int ret;
 508
 509         eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
 510                                     EAP_VENDOR_IETF, EAP_TYPE_PAX, "PAX");
 511         if (eap == NULL)
 512                 return -1;
 513
 514         eap->init = eap_pax_init;
 515         eap->deinit = eap_pax_deinit;
 516         eap->process = eap_pax_process;
 517         eap->isKeyAvailable = eap_pax_isKeyAvailable;
 518         eap->getKey = eap_pax_getKey;
 519         eap->get_emsk = eap_pax_get_emsk;
 520
 521         ret = eap_peer_method_register(eap);
 522         if (ret)
 523                 eap_peer_method_free(eap);
 524         return ret;
 525 }