libeap/src/rsn_supp/preauth.c

   1 /*
   2  * RSN pre-authentication (supplicant)
   3  * Copyright (c) 2003-2015, 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 "wpa.h"
  13 #include "eloop.h"
  14 #include "l2_packet/l2_packet.h"
  15 #include "eapol_supp/eapol_supp_sm.h"
  16 #include "preauth.h"
  17 #include "pmksa_cache.h"
  18 #include "wpa_i.h"
  19
  20
  21 #ifdef IEEE8021X_EAPOL
  22
  23 #define PMKID_CANDIDATE_PRIO_SCAN 1000
  24
  25
  26 struct rsn_pmksa_candidate {
  27         struct dl_list list;
  28         u8 bssid[ETH_ALEN];
  29         int priority;
  30 };
  31
  32
  33 /**
  34  * pmksa_candidate_free - Free all entries in PMKSA candidate list
  35  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  36  */
  37 void pmksa_candidate_free(struct wpa_sm *sm)
  38 {
  39         struct rsn_pmksa_candidate *entry, *n;
  40
  41         if (sm == NULL)
  42                 return;
  43
  44         dl_list_for_each_safe(entry, n, &sm->pmksa_candidates,
  45                               struct rsn_pmksa_candidate, list) {
  46                 dl_list_del(&entry->list);
  47                 os_free(entry);
  48         }
  49 }
  50
  51
  52 static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
  53                                 const u8 *buf, size_t len)
  54 {
  55         struct wpa_sm *sm = ctx;
  56
  57         wpa_printf(MSG_DEBUG, "RX pre-auth from " MACSTR, MAC2STR(src_addr));
  58         wpa_hexdump(MSG_MSGDUMP, "RX pre-auth", buf, len);
  59
  60         if (sm->preauth_eapol == NULL ||
  61             is_zero_ether_addr(sm->preauth_bssid) ||
  62             os_memcmp(sm->preauth_bssid, src_addr, ETH_ALEN) != 0) {
  63                 wpa_printf(MSG_WARNING, "RSN pre-auth frame received from "
  64                            "unexpected source " MACSTR " - dropped",
  65                            MAC2STR(src_addr));
  66                 return;
  67         }
  68
  69         eapol_sm_rx_eapol(sm->preauth_eapol, src_addr, buf, len);
  70 }
  71
  72
  73 static void rsn_preauth_eapol_cb(struct eapol_sm *eapol,
  74                                  enum eapol_supp_result result,
  75                                  void *ctx)
  76 {
  77         struct wpa_sm *sm = ctx;
  78         u8 pmk[PMK_LEN];
  79
  80         if (result == EAPOL_SUPP_RESULT_SUCCESS) {
  81                 int res, pmk_len;
  82                 pmk_len = PMK_LEN;
  83                 res = eapol_sm_get_key(eapol, pmk, PMK_LEN);
  84                 if (res) {
  85                         /*
  86                          * EAP-LEAP is an exception from other EAP methods: it
  87                          * uses only 16-byte PMK.
  88                          */
  89                         res = eapol_sm_get_key(eapol, pmk, 16);
  90                         pmk_len = 16;
  91                 }
  92                 if (res == 0) {
  93                         wpa_hexdump_key(MSG_DEBUG, "RSN: PMK from pre-auth",
  94                                         pmk, pmk_len);
  95                         sm->pmk_len = pmk_len;
  96                         pmksa_cache_add(sm->pmksa, pmk, pmk_len,
  97                                         NULL, 0,
  98                                         sm->preauth_bssid, sm->own_addr,
  99                                         sm->network_ctx,
 100                                         WPA_KEY_MGMT_IEEE8021X);
 101                 } else {
 102                         wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
 103                                 "RSN: failed to get master session key from "
 104                                 "pre-auth EAPOL state machines");
 105                         result = EAPOL_SUPP_RESULT_FAILURE;
 106                 }
 107         }
 108
 109         wpa_msg(sm->ctx->msg_ctx, MSG_INFO, "RSN: pre-authentication with "
 110                 MACSTR " %s", MAC2STR(sm->preauth_bssid),
 111                 result == EAPOL_SUPP_RESULT_SUCCESS ? "completed successfully" :
 112                 "failed");
 113
 114         rsn_preauth_deinit(sm);
 115         rsn_preauth_candidate_process(sm);
 116 }
 117
 118
 119 static void rsn_preauth_timeout(void *eloop_ctx, void *timeout_ctx)
 120 {
 121         struct wpa_sm *sm = eloop_ctx;
 122
 123         wpa_msg(sm->ctx->msg_ctx, MSG_INFO, "RSN: pre-authentication with "
 124                 MACSTR " timed out", MAC2STR(sm->preauth_bssid));
 125         rsn_preauth_deinit(sm);
 126         rsn_preauth_candidate_process(sm);
 127 }
 128
 129
 130 static int rsn_preauth_eapol_send(void *ctx, int type, const u8 *buf,
 131                                   size_t len)
 132 {
 133         struct wpa_sm *sm = ctx;
 134         u8 *msg;
 135         size_t msglen;
 136         int res;
 137
 138         /* TODO: could add l2_packet_sendmsg that allows fragments to avoid
 139          * extra copy here */
 140
 141         if (sm->l2_preauth == NULL)
 142                 return -1;
 143
 144         msg = wpa_sm_alloc_eapol(sm, type, buf, len, &msglen, NULL);
 145         if (msg == NULL)
 146                 return -1;
 147
 148         wpa_hexdump(MSG_MSGDUMP, "TX EAPOL (preauth)", msg, msglen);
 149         res = l2_packet_send(sm->l2_preauth, sm->preauth_bssid,
 150                              ETH_P_RSN_PREAUTH, msg, msglen);
 151         os_free(msg);
 152         return res;
 153 }
 154
 155
 156 /**
 157  * rsn_preauth_init - Start new RSN pre-authentication
 158  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 159  * @dst: Authenticator address (BSSID) with which to preauthenticate
 160  * @eap_conf: Current EAP configuration
 161  * Returns: 0 on success, -1 on another pre-authentication is in progress,
 162  * -2 on layer 2 packet initialization failure, -3 on EAPOL state machine
 163  * initialization failure, -4 on memory allocation failure
 164  *
 165  * This function request an RSN pre-authentication with a given destination
 166  * address. This is usually called for PMKSA candidates found from scan results
 167  * or from driver reports. In addition, ctrl_iface PREAUTH command can trigger
 168  * pre-authentication.
 169  */
 170 int rsn_preauth_init(struct wpa_sm *sm, const u8 *dst,
 171                      struct eap_peer_config *eap_conf)
 172 {
 173         struct eapol_config eapol_conf;
 174         struct eapol_ctx *ctx;
 175         int ret;
 176
 177         if (sm->preauth_eapol)
 178                 return -1;
 179
 180         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG,
 181                 "RSN: starting pre-authentication with " MACSTR, MAC2STR(dst));
 182
 183         sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
 184                                         ETH_P_RSN_PREAUTH,
 185                                         rsn_preauth_receive, sm, 0);
 186         if (sm->l2_preauth == NULL) {
 187                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
 188                            "processing for pre-authentication");
 189                 return -2;
 190         }
 191
 192         if (sm->bridge_ifname) {
 193                 sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
 194                                                    sm->own_addr,
 195                                                    ETH_P_RSN_PREAUTH,
 196                                                    rsn_preauth_receive, sm, 0);
 197                 if (sm->l2_preauth_br == NULL) {
 198                         wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
 199                                    "packet processing (bridge) for "
 200                                    "pre-authentication");
 201                         ret = -2;
 202                         goto fail;
 203                 }
 204         }
 205
 206         ctx = os_zalloc(sizeof(*ctx));
 207         if (ctx == NULL) {
 208                 wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
 209                 ret = -4;
 210                 goto fail;
 211         }
 212         ctx->ctx = sm->ctx->ctx;
 213         ctx->msg_ctx = sm->ctx->ctx;
 214         ctx->preauth = 1;
 215         ctx->cb = rsn_preauth_eapol_cb;
 216         ctx->cb_ctx = sm;
 217         ctx->scard_ctx = sm->scard_ctx;
 218         ctx->eapol_send = rsn_preauth_eapol_send;
 219         ctx->eapol_send_ctx = sm;
 220         ctx->set_config_blob = sm->ctx->set_config_blob;
 221         ctx->get_config_blob = sm->ctx->get_config_blob;
 222
 223         sm->preauth_eapol = eapol_sm_init(ctx);
 224         if (sm->preauth_eapol == NULL) {
 225                 os_free(ctx);
 226                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
 227                            "state machines for pre-authentication");
 228                 ret = -3;
 229                 goto fail;
 230         }
 231         os_memset(&eapol_conf, 0, sizeof(eapol_conf));
 232         eapol_conf.accept_802_1x_keys = 0;
 233         eapol_conf.required_keys = 0;
 234         eapol_conf.fast_reauth = sm->fast_reauth;
 235         eapol_conf.workaround = sm->eap_workaround;
 236         eapol_sm_notify_config(sm->preauth_eapol, eap_conf, &eapol_conf);
 237         /*
 238          * Use a shorter startPeriod with preauthentication since the first
 239          * preauth EAPOL-Start frame may end up being dropped due to race
 240          * condition in the AP between the data receive and key configuration
 241          * after the 4-Way Handshake.
 242          */
 243         eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
 244         os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
 245
 246         eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
 247         /* 802.1X::portControl = Auto */
 248         eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
 249
 250         eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
 251                                rsn_preauth_timeout, sm, NULL);
 252
 253         return 0;
 254
 255 fail:
 256         if (sm->l2_preauth_br) {
 257                 l2_packet_deinit(sm->l2_preauth_br);
 258                 sm->l2_preauth_br = NULL;
 259         }
 260         l2_packet_deinit(sm->l2_preauth);
 261         sm->l2_preauth = NULL;
 262         return ret;
 263 }
 264
 265
 266 /**
 267  * rsn_preauth_deinit - Abort RSN pre-authentication
 268  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 269  *
 270  * This function aborts the current RSN pre-authentication (if one is started)
 271  * and frees resources allocated for it.
 272  */
 273 void rsn_preauth_deinit(struct wpa_sm *sm)
 274 {
 275         if (sm == NULL || !sm->preauth_eapol)
 276                 return;
 277
 278         eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
 279         eapol_sm_deinit(sm->preauth_eapol);
 280         sm->preauth_eapol = NULL;
 281         os_memset(sm->preauth_bssid, 0, ETH_ALEN);
 282
 283         l2_packet_deinit(sm->l2_preauth);
 284         sm->l2_preauth = NULL;
 285         if (sm->l2_preauth_br) {
 286                 l2_packet_deinit(sm->l2_preauth_br);
 287                 sm->l2_preauth_br = NULL;
 288         }
 289 }
 290
 291
 292 /**
 293  * rsn_preauth_candidate_process - Process PMKSA candidates
 294  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 295  *
 296  * Go through the PMKSA candidates and start pre-authentication if a candidate
 297  * without an existing PMKSA cache entry is found. Processed candidates will be
 298  * removed from the list.
 299  */
 300 void rsn_preauth_candidate_process(struct wpa_sm *sm)
 301 {
 302         struct rsn_pmksa_candidate *candidate, *n;
 303
 304         if (dl_list_empty(&sm->pmksa_candidates))
 305                 return;
 306
 307         /* TODO: drop priority for old candidate entries */
 308
 309         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
 310                 "list");
 311         if (sm->preauth_eapol ||
 312             sm->proto != WPA_PROTO_RSN ||
 313             wpa_sm_get_state(sm) != WPA_COMPLETED ||
 314             (sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X &&
 315              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SHA256 &&
 316              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SUITE_B &&
 317              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SUITE_B_192)) {
 318                 wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: not in suitable "
 319                         "state for new pre-authentication");
 320                 return; /* invalid state for new pre-auth */
 321         }
 322
 323         dl_list_for_each_safe(candidate, n, &sm->pmksa_candidates,
 324                               struct rsn_pmksa_candidate, list) {
 325                 struct rsn_pmksa_cache_entry *p = NULL;
 326                 p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL, NULL);
 327                 if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
 328                     (p == NULL || p->opportunistic)) {
 329                         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA "
 330                                 "candidate " MACSTR
 331                                 " selected for pre-authentication",
 332                                 MAC2STR(candidate->bssid));
 333                         dl_list_del(&candidate->list);
 334                         rsn_preauth_init(sm, candidate->bssid,
 335                                          sm->eap_conf_ctx);
 336                         os_free(candidate);
 337                         return;
 338                 }
 339                 wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA candidate "
 340                         MACSTR " does not need pre-authentication anymore",
 341                         MAC2STR(candidate->bssid));
 342                 /* Some drivers (e.g., NDIS) expect to get notified about the
 343                  * PMKIDs again, so report the existing data now. */
 344                 if (p) {
 345                         wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
 346                 }
 347
 348                 dl_list_del(&candidate->list);
 349                 os_free(candidate);
 350         }
 351         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
 352                 "candidates");
 353 }
 354
 355
 356 /**
 357  * pmksa_candidate_add - Add a new PMKSA candidate
 358  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 359  * @bssid: BSSID (authenticator address) of the candidate
 360  * @prio: Priority (the smaller number, the higher priority)
 361  * @preauth: Whether the candidate AP advertises support for pre-authentication
 362  *
 363  * This function is used to add PMKSA candidates for RSN pre-authentication. It
 364  * is called from scan result processing and from driver events for PMKSA
 365  * candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
 366  */
 367 void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
 368                          int prio, int preauth)
 369 {
 370         struct rsn_pmksa_candidate *cand, *pos;
 371
 372         if (sm->network_ctx && sm->proactive_key_caching)
 373                 pmksa_cache_get_opportunistic(sm->pmksa, sm->network_ctx,
 374                                               bssid);
 375
 376         if (!preauth) {
 377                 wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
 378                            "preauth flag");
 379                 return;
 380         }
 381
 382         /* If BSSID already on candidate list, update the priority of the old
 383          * entry. Do not override priority based on normal scan results. */
 384         cand = NULL;
 385         dl_list_for_each(pos, &sm->pmksa_candidates,
 386                          struct rsn_pmksa_candidate, list) {
 387                 if (os_memcmp(pos->bssid, bssid, ETH_ALEN) == 0) {
 388                         cand = pos;
 389                         break;
 390                 }
 391         }
 392
 393         if (cand) {
 394                 dl_list_del(&cand->list);
 395                 if (prio < PMKID_CANDIDATE_PRIO_SCAN)
 396                         cand->priority = prio;
 397         } else {
 398                 cand = os_zalloc(sizeof(*cand));
 399                 if (cand == NULL)
 400                         return;
 401                 os_memcpy(cand->bssid, bssid, ETH_ALEN);
 402                 cand->priority = prio;
 403         }
 404
 405         /* Add candidate to the list; order by increasing priority value. i.e.,
 406          * highest priority (smallest value) first. */
 407         dl_list_for_each(pos, &sm->pmksa_candidates,
 408                          struct rsn_pmksa_candidate, list) {
 409                 if (cand->priority <= pos->priority) {
 410                         if (!pos->list.prev) {
 411                                 /*
 412                                  * This cannot really happen in pracrice since
 413                                  * pos was fetched from the list and the prev
 414                                  * pointer must be set. It looks like clang
 415                                  * static analyzer gets confused with the
 416                                  * dl_list_del(&cand->list) call above and ends
 417                                  * up assuming pos->list.prev could be NULL.
 418                                  */
 419                                 os_free(cand);
 420                                 return;
 421                         }
 422                         dl_list_add(pos->list.prev, &cand->list);
 423                         cand = NULL;
 424                         break;
 425                 }
 426         }
 427         if (cand)
 428                 dl_list_add_tail(&sm->pmksa_candidates, &cand->list);
 429
 430         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: added PMKSA cache "
 431                 "candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
 432         rsn_preauth_candidate_process(sm);
 433 }
 434
 435
 436 /* TODO: schedule periodic scans if current AP supports preauth */
 437
 438 /**
 439  * rsn_preauth_scan_results - Start processing scan results for canditates
 440  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 441  * Returns: 0 if ready to process results or -1 to skip processing
 442  *
 443  * This functions is used to notify RSN code about start of new scan results
 444  * processing. The actual scan results will be provided by calling
 445  * rsn_preauth_scan_result() for each BSS if this function returned 0.
 446  */
 447 int rsn_preauth_scan_results(struct wpa_sm *sm)
 448 {
 449         if (sm->ssid_len == 0)
 450                 return -1;
 451
 452         /*
 453          * TODO: is it ok to free all candidates? What about the entries
 454          * received from EVENT_PMKID_CANDIDATE?
 455          */
 456         pmksa_candidate_free(sm);
 457
 458         return 0;
 459 }
 460
 461
 462 /**
 463  * rsn_preauth_scan_result - Processing scan result for PMKSA canditates
 464  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 465  *
 466  * Add all suitable APs (Authenticators) from scan results into PMKSA
 467  * candidate list.
 468  */
 469 void rsn_preauth_scan_result(struct wpa_sm *sm, const u8 *bssid,
 470                              const u8 *ssid, const u8 *rsn)
 471 {
 472         struct wpa_ie_data ie;
 473         struct rsn_pmksa_cache_entry *pmksa;
 474
 475         if (ssid[1] != sm->ssid_len ||
 476             os_memcmp(ssid + 2, sm->ssid, sm->ssid_len) != 0)
 477                 return; /* Not for the current SSID */
 478
 479         if (os_memcmp(bssid, sm->bssid, ETH_ALEN) == 0)
 480                 return; /* Ignore current AP */
 481
 482         if (wpa_parse_wpa_ie(rsn, 2 + rsn[1], &ie))
 483                 return;
 484
 485         pmksa = pmksa_cache_get(sm->pmksa, bssid, NULL, NULL);
 486         if (pmksa && (!pmksa->opportunistic ||
 487                       !(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
 488                 return;
 489
 490         /* Give less priority to candidates found from normal scan results. */
 491         pmksa_candidate_add(sm, bssid, PMKID_CANDIDATE_PRIO_SCAN,
 492                             ie.capabilities & WPA_CAPABILITY_PREAUTH);
 493 }
 494
 495
 496 #ifdef CONFIG_CTRL_IFACE
 497 /**
 498  * rsn_preauth_get_status - Get pre-authentication status
 499  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 500  * @buf: Buffer for status information
 501  * @buflen: Maximum buffer length
 502  * @verbose: Whether to include verbose status information
 503  * Returns: Number of bytes written to buf.
 504  *
 505  * Query WPA2 pre-authentication for status information. This function fills in
 506  * a text area with current status information. If the buffer (buf) is not
 507  * large enough, status information will be truncated to fit the buffer.
 508  */
 509 int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
 510                            int verbose)
 511 {
 512         char *pos = buf, *end = buf + buflen;
 513         int res, ret;
 514
 515         if (sm->preauth_eapol) {
 516                 ret = os_snprintf(pos, end - pos, "Pre-authentication "
 517                                   "EAPOL state machines:\n");
 518                 if (os_snprintf_error(end - pos, ret))
 519                         return pos - buf;
 520                 pos += ret;
 521                 res = eapol_sm_get_status(sm->preauth_eapol,
 522                                           pos, end - pos, verbose);
 523                 if (res >= 0)
 524                         pos += res;
 525         }
 526
 527         return pos - buf;
 528 }
 529 #endif /* CONFIG_CTRL_IFACE */
 530
 531
 532 /**
 533  * rsn_preauth_in_progress - Verify whether pre-authentication is in progress
 534  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 535  */
 536 int rsn_preauth_in_progress(struct wpa_sm *sm)
 537 {
 538         return sm->preauth_eapol != NULL;
 539 }
 540
 541 #endif /* IEEE8021X_EAPOL */