src/rsn_supp/preauth.c

   1 /*
   2  * RSN pre-authentication (supplicant)
   3  * Copyright (c) 2003-2012, 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
 176         if (sm->preauth_eapol)
 177                 return -1;
 178
 179         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG,
 180                 "RSN: starting pre-authentication with " MACSTR, MAC2STR(dst));
 181
 182         sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
 183                                         ETH_P_RSN_PREAUTH,
 184                                         rsn_preauth_receive, sm, 0);
 185         if (sm->l2_preauth == NULL) {
 186                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
 187                            "processing for pre-authentication");
 188                 return -2;
 189         }
 190
 191         if (sm->bridge_ifname) {
 192                 sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
 193                                                    sm->own_addr,
 194                                                    ETH_P_RSN_PREAUTH,
 195                                                    rsn_preauth_receive, sm, 0);
 196                 if (sm->l2_preauth_br == NULL) {
 197                         wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
 198                                    "packet processing (bridge) for "
 199                                    "pre-authentication");
 200                         return -2;
 201                 }
 202         }
 203
 204         ctx = os_zalloc(sizeof(*ctx));
 205         if (ctx == NULL) {
 206                 wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
 207                 return -4;
 208         }
 209         ctx->ctx = sm->ctx->ctx;
 210         ctx->msg_ctx = sm->ctx->ctx;
 211         ctx->preauth = 1;
 212         ctx->cb = rsn_preauth_eapol_cb;
 213         ctx->cb_ctx = sm;
 214         ctx->scard_ctx = sm->scard_ctx;
 215         ctx->eapol_send = rsn_preauth_eapol_send;
 216         ctx->eapol_send_ctx = sm;
 217         ctx->set_config_blob = sm->ctx->set_config_blob;
 218         ctx->get_config_blob = sm->ctx->get_config_blob;
 219
 220         sm->preauth_eapol = eapol_sm_init(ctx);
 221         if (sm->preauth_eapol == NULL) {
 222                 os_free(ctx);
 223                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
 224                            "state machines for pre-authentication");
 225                 return -3;
 226         }
 227         os_memset(&eapol_conf, 0, sizeof(eapol_conf));
 228         eapol_conf.accept_802_1x_keys = 0;
 229         eapol_conf.required_keys = 0;
 230         eapol_conf.fast_reauth = sm->fast_reauth;
 231         eapol_conf.workaround = sm->eap_workaround;
 232         eapol_sm_notify_config(sm->preauth_eapol, eap_conf, &eapol_conf);
 233         /*
 234          * Use a shorter startPeriod with preauthentication since the first
 235          * preauth EAPOL-Start frame may end up being dropped due to race
 236          * condition in the AP between the data receive and key configuration
 237          * after the 4-Way Handshake.
 238          */
 239         eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
 240         os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
 241
 242         eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
 243         /* 802.1X::portControl = Auto */
 244         eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
 245
 246         eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
 247                                rsn_preauth_timeout, sm, NULL);
 248
 249         return 0;
 250 }
 251
 252
 253 /**
 254  * rsn_preauth_deinit - Abort RSN pre-authentication
 255  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 256  *
 257  * This function aborts the current RSN pre-authentication (if one is started)
 258  * and frees resources allocated for it.
 259  */
 260 void rsn_preauth_deinit(struct wpa_sm *sm)
 261 {
 262         if (sm == NULL || !sm->preauth_eapol)
 263                 return;
 264
 265         eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
 266         eapol_sm_deinit(sm->preauth_eapol);
 267         sm->preauth_eapol = NULL;
 268         os_memset(sm->preauth_bssid, 0, ETH_ALEN);
 269
 270         l2_packet_deinit(sm->l2_preauth);
 271         sm->l2_preauth = NULL;
 272         if (sm->l2_preauth_br) {
 273                 l2_packet_deinit(sm->l2_preauth_br);
 274                 sm->l2_preauth_br = NULL;
 275         }
 276 }
 277
 278
 279 /**
 280  * rsn_preauth_candidate_process - Process PMKSA candidates
 281  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 282  *
 283  * Go through the PMKSA candidates and start pre-authentication if a candidate
 284  * without an existing PMKSA cache entry is found. Processed candidates will be
 285  * removed from the list.
 286  */
 287 void rsn_preauth_candidate_process(struct wpa_sm *sm)
 288 {
 289         struct rsn_pmksa_candidate *candidate, *n;
 290
 291         if (dl_list_empty(&sm->pmksa_candidates))
 292                 return;
 293
 294         /* TODO: drop priority for old candidate entries */
 295
 296         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
 297                 "list");
 298         if (sm->preauth_eapol ||
 299             sm->proto != WPA_PROTO_RSN ||
 300             wpa_sm_get_state(sm) != WPA_COMPLETED ||
 301             (sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X &&
 302              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SHA256 &&
 303              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SUITE_B)) {
 304                 wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: not in suitable "
 305                         "state for new pre-authentication");
 306                 return; /* invalid state for new pre-auth */
 307         }
 308
 309         dl_list_for_each_safe(candidate, n, &sm->pmksa_candidates,
 310                               struct rsn_pmksa_candidate, list) {
 311                 struct rsn_pmksa_cache_entry *p = NULL;
 312                 p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL, NULL);
 313                 if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
 314                     (p == NULL || p->opportunistic)) {
 315                         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA "
 316                                 "candidate " MACSTR
 317                                 " selected for pre-authentication",
 318                                 MAC2STR(candidate->bssid));
 319                         dl_list_del(&candidate->list);
 320                         rsn_preauth_init(sm, candidate->bssid,
 321                                          sm->eap_conf_ctx);
 322                         os_free(candidate);
 323                         return;
 324                 }
 325                 wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: PMKSA candidate "
 326                         MACSTR " does not need pre-authentication anymore",
 327                         MAC2STR(candidate->bssid));
 328                 /* Some drivers (e.g., NDIS) expect to get notified about the
 329                  * PMKIDs again, so report the existing data now. */
 330                 if (p) {
 331                         wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
 332                 }
 333
 334                 dl_list_del(&candidate->list);
 335                 os_free(candidate);
 336         }
 337         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
 338                 "candidates");
 339 }
 340
 341
 342 /**
 343  * pmksa_candidate_add - Add a new PMKSA candidate
 344  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 345  * @bssid: BSSID (authenticator address) of the candidate
 346  * @prio: Priority (the smaller number, the higher priority)
 347  * @preauth: Whether the candidate AP advertises support for pre-authentication
 348  *
 349  * This function is used to add PMKSA candidates for RSN pre-authentication. It
 350  * is called from scan result processing and from driver events for PMKSA
 351  * candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
 352  */
 353 void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
 354                          int prio, int preauth)
 355 {
 356         struct rsn_pmksa_candidate *cand, *pos;
 357
 358         if (sm->network_ctx && sm->proactive_key_caching)
 359                 pmksa_cache_get_opportunistic(sm->pmksa, sm->network_ctx,
 360                                               bssid);
 361
 362         if (!preauth) {
 363                 wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
 364                            "preauth flag");
 365                 return;
 366         }
 367
 368         /* If BSSID already on candidate list, update the priority of the old
 369          * entry. Do not override priority based on normal scan results. */
 370         cand = NULL;
 371         dl_list_for_each(pos, &sm->pmksa_candidates,
 372                          struct rsn_pmksa_candidate, list) {
 373                 if (os_memcmp(pos->bssid, bssid, ETH_ALEN) == 0) {
 374                         cand = pos;
 375                         break;
 376                 }
 377         }
 378
 379         if (cand) {
 380                 dl_list_del(&cand->list);
 381                 if (prio < PMKID_CANDIDATE_PRIO_SCAN)
 382                         cand->priority = prio;
 383         } else {
 384                 cand = os_zalloc(sizeof(*cand));
 385                 if (cand == NULL)
 386                         return;
 387                 os_memcpy(cand->bssid, bssid, ETH_ALEN);
 388                 cand->priority = prio;
 389         }
 390
 391         /* Add candidate to the list; order by increasing priority value. i.e.,
 392          * highest priority (smallest value) first. */
 393         dl_list_for_each(pos, &sm->pmksa_candidates,
 394                          struct rsn_pmksa_candidate, list) {
 395                 if (cand->priority <= pos->priority) {
 396                         if (!pos->list.prev) {
 397                                 /*
 398                                  * This cannot really happen in pracrice since
 399                                  * pos was fetched from the list and the prev
 400                                  * pointer must be set. It looks like clang
 401                                  * static analyzer gets confused with the
 402                                  * dl_list_del(&cand->list) call above and ends
 403                                  * up assuming pos->list.prev could be NULL.
 404                                  */
 405                                 os_free(cand);
 406                                 return;
 407                         }
 408                         dl_list_add(pos->list.prev, &cand->list);
 409                         cand = NULL;
 410                         break;
 411                 }
 412         }
 413         if (cand)
 414                 dl_list_add_tail(&sm->pmksa_candidates, &cand->list);
 415
 416         wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: added PMKSA cache "
 417                 "candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
 418         rsn_preauth_candidate_process(sm);
 419 }
 420
 421
 422 /* TODO: schedule periodic scans if current AP supports preauth */
 423
 424 /**
 425  * rsn_preauth_scan_results - Start processing scan results for canditates
 426  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 427  * Returns: 0 if ready to process results or -1 to skip processing
 428  *
 429  * This functions is used to notify RSN code about start of new scan results
 430  * processing. The actual scan results will be provided by calling
 431  * rsn_preauth_scan_result() for each BSS if this function returned 0.
 432  */
 433 int rsn_preauth_scan_results(struct wpa_sm *sm)
 434 {
 435         if (sm->ssid_len == 0)
 436                 return -1;
 437
 438         /*
 439          * TODO: is it ok to free all candidates? What about the entries
 440          * received from EVENT_PMKID_CANDIDATE?
 441          */
 442         pmksa_candidate_free(sm);
 443
 444         return 0;
 445 }
 446
 447
 448 /**
 449  * rsn_preauth_scan_result - Processing scan result for PMKSA canditates
 450  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 451  *
 452  * Add all suitable APs (Authenticators) from scan results into PMKSA
 453  * candidate list.
 454  */
 455 void rsn_preauth_scan_result(struct wpa_sm *sm, const u8 *bssid,
 456                              const u8 *ssid, const u8 *rsn)
 457 {
 458         struct wpa_ie_data ie;
 459         struct rsn_pmksa_cache_entry *pmksa;
 460
 461         if (ssid[1] != sm->ssid_len ||
 462             os_memcmp(ssid + 2, sm->ssid, sm->ssid_len) != 0)
 463                 return; /* Not for the current SSID */
 464
 465         if (os_memcmp(bssid, sm->bssid, ETH_ALEN) == 0)
 466                 return; /* Ignore current AP */
 467
 468         if (wpa_parse_wpa_ie(rsn, 2 + rsn[1], &ie))
 469                 return;
 470
 471         pmksa = pmksa_cache_get(sm->pmksa, bssid, NULL, NULL);
 472         if (pmksa && (!pmksa->opportunistic ||
 473                       !(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
 474                 return;
 475
 476         /* Give less priority to candidates found from normal scan results. */
 477         pmksa_candidate_add(sm, bssid, PMKID_CANDIDATE_PRIO_SCAN,
 478                             ie.capabilities & WPA_CAPABILITY_PREAUTH);
 479 }
 480
 481
 482 #ifdef CONFIG_CTRL_IFACE
 483 /**
 484  * rsn_preauth_get_status - Get pre-authentication status
 485  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 486  * @buf: Buffer for status information
 487  * @buflen: Maximum buffer length
 488  * @verbose: Whether to include verbose status information
 489  * Returns: Number of bytes written to buf.
 490  *
 491  * Query WPA2 pre-authentication for status information. This function fills in
 492  * a text area with current status information. If the buffer (buf) is not
 493  * large enough, status information will be truncated to fit the buffer.
 494  */
 495 int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
 496                            int verbose)
 497 {
 498         char *pos = buf, *end = buf + buflen;
 499         int res, ret;
 500
 501         if (sm->preauth_eapol) {
 502                 ret = os_snprintf(pos, end - pos, "Pre-authentication "
 503                                   "EAPOL state machines:\n");
 504                 if (ret < 0 || ret >= end - pos)
 505                         return pos - buf;
 506                 pos += ret;
 507                 res = eapol_sm_get_status(sm->preauth_eapol,
 508                                           pos, end - pos, verbose);
 509                 if (res >= 0)
 510                         pos += res;
 511         }
 512
 513         return pos - buf;
 514 }
 515 #endif /* CONFIG_CTRL_IFACE */
 516
 517
 518 /**
 519  * rsn_preauth_in_progress - Verify whether pre-authentication is in progress
 520  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 521  */
 522 int rsn_preauth_in_progress(struct wpa_sm *sm)
 523 {
 524         return sm->preauth_eapol != NULL;
 525 }
 526
 527 #endif /* IEEE8021X_EAPOL */