contrib/hostapd/src/rsn_supp/preauth.c

   1 /*
   2  * WPA Supplicant - RSN pre-authentication
   3  * Copyright (c) 2003-2008, 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
  15 #include "includes.h"
  16
  17 #include "common.h"
  18 #include "wpa.h"
  19 #include "drivers/driver.h"
  20 #include "eloop.h"
  21 #include "l2_packet/l2_packet.h"
  22 #include "eapol_supp/eapol_supp_sm.h"
  23 #include "preauth.h"
  24 #include "pmksa_cache.h"
  25 #include "wpa_i.h"
  26 #include "ieee802_11_defs.h"
  27
  28
  29 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
  30
  31 #define PMKID_CANDIDATE_PRIO_SCAN 1000
  32
  33
  34 struct rsn_pmksa_candidate {
  35         struct rsn_pmksa_candidate *next;
  36         u8 bssid[ETH_ALEN];
  37         int priority;
  38 };
  39
  40
  41 /**
  42  * pmksa_candidate_free - Free all entries in PMKSA candidate list
  43  * @sm: Pointer to WPA state machine data from wpa_sm_init()
  44  */
  45 void pmksa_candidate_free(struct wpa_sm *sm)
  46 {
  47         struct rsn_pmksa_candidate *entry, *prev;
  48
  49         if (sm == NULL)
  50                 return;
  51
  52         entry = sm->pmksa_candidates;
  53         sm->pmksa_candidates = NULL;
  54         while (entry) {
  55                 prev = entry;
  56                 entry = entry->next;
  57                 os_free(prev);
  58         }
  59 }
  60
  61
  62 static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
  63                                 const u8 *buf, size_t len)
  64 {
  65         struct wpa_sm *sm = ctx;
  66
  67         wpa_printf(MSG_DEBUG, "RX pre-auth from " MACSTR, MAC2STR(src_addr));
  68         wpa_hexdump(MSG_MSGDUMP, "RX pre-auth", buf, len);
  69
  70         if (sm->preauth_eapol == NULL ||
  71             is_zero_ether_addr(sm->preauth_bssid) ||
  72             os_memcmp(sm->preauth_bssid, src_addr, ETH_ALEN) != 0) {
  73                 wpa_printf(MSG_WARNING, "RSN pre-auth frame received from "
  74                            "unexpected source " MACSTR " - dropped",
  75                            MAC2STR(src_addr));
  76                 return;
  77         }
  78
  79         eapol_sm_rx_eapol(sm->preauth_eapol, src_addr, buf, len);
  80 }
  81
  82
  83 static void rsn_preauth_eapol_cb(struct eapol_sm *eapol, int success,
  84                                  void *ctx)
  85 {
  86         struct wpa_sm *sm = ctx;
  87         u8 pmk[PMK_LEN];
  88
  89         if (success) {
  90                 int res, pmk_len;
  91                 pmk_len = PMK_LEN;
  92                 res = eapol_sm_get_key(eapol, pmk, PMK_LEN);
  93                 if (res) {
  94                         /*
  95                          * EAP-LEAP is an exception from other EAP methods: it
  96                          * uses only 16-byte PMK.
  97                          */
  98                         res = eapol_sm_get_key(eapol, pmk, 16);
  99                         pmk_len = 16;
 100                 }
 101                 if (res == 0) {
 102                         wpa_hexdump_key(MSG_DEBUG, "RSN: PMK from pre-auth",
 103                                         pmk, pmk_len);
 104                         sm->pmk_len = pmk_len;
 105                         pmksa_cache_add(sm->pmksa, pmk, pmk_len,
 106                                         sm->preauth_bssid, sm->own_addr,
 107                                         sm->network_ctx,
 108                                         WPA_KEY_MGMT_IEEE8021X);
 109                 } else {
 110                         wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: failed to get "
 111                                 "master session key from pre-auth EAPOL state "
 112                                 "machines");
 113                         success = 0;
 114                 }
 115         }
 116
 117         wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
 118                 " %s", MAC2STR(sm->preauth_bssid),
 119                 success ? "completed successfully" : "failed");
 120
 121         rsn_preauth_deinit(sm);
 122         rsn_preauth_candidate_process(sm);
 123 }
 124
 125
 126 static void rsn_preauth_timeout(void *eloop_ctx, void *timeout_ctx)
 127 {
 128         struct wpa_sm *sm = eloop_ctx;
 129
 130         wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
 131                 " timed out", MAC2STR(sm->preauth_bssid));
 132         rsn_preauth_deinit(sm);
 133         rsn_preauth_candidate_process(sm);
 134 }
 135
 136
 137 static int rsn_preauth_eapol_send(void *ctx, int type, const u8 *buf,
 138                                   size_t len)
 139 {
 140         struct wpa_sm *sm = ctx;
 141         u8 *msg;
 142         size_t msglen;
 143         int res;
 144
 145         /* TODO: could add l2_packet_sendmsg that allows fragments to avoid
 146          * extra copy here */
 147
 148         if (sm->l2_preauth == NULL)
 149                 return -1;
 150
 151         msg = wpa_sm_alloc_eapol(sm, type, buf, len, &msglen, NULL);
 152         if (msg == NULL)
 153                 return -1;
 154
 155         wpa_hexdump(MSG_MSGDUMP, "TX EAPOL (preauth)", msg, msglen);
 156         res = l2_packet_send(sm->l2_preauth, sm->preauth_bssid,
 157                              ETH_P_RSN_PREAUTH, msg, msglen);
 158         os_free(msg);
 159         return res;
 160 }
 161
 162
 163 /**
 164  * rsn_preauth_init - Start new RSN pre-authentication
 165  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 166  * @dst: Authenticator address (BSSID) with which to preauthenticate
 167  * @eap_conf: Current EAP configuration
 168  * Returns: 0 on success, -1 on another pre-authentication is in progress,
 169  * -2 on layer 2 packet initialization failure, -3 on EAPOL state machine
 170  * initialization failure, -4 on memory allocation failure
 171  *
 172  * This function request an RSN pre-authentication with a given destination
 173  * address. This is usually called for PMKSA candidates found from scan results
 174  * or from driver reports. In addition, ctrl_iface PREAUTH command can trigger
 175  * pre-authentication.
 176  */
 177 int rsn_preauth_init(struct wpa_sm *sm, const u8 *dst,
 178                      struct eap_peer_config *eap_conf)
 179 {
 180         struct eapol_config eapol_conf;
 181         struct eapol_ctx *ctx;
 182
 183         if (sm->preauth_eapol)
 184                 return -1;
 185
 186         wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: starting pre-authentication "
 187                 "with " MACSTR, MAC2STR(dst));
 188
 189         sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
 190                                         ETH_P_RSN_PREAUTH,
 191                                         rsn_preauth_receive, sm, 0);
 192         if (sm->l2_preauth == NULL) {
 193                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
 194                            "processing for pre-authentication");
 195                 return -2;
 196         }
 197
 198         if (sm->bridge_ifname) {
 199                 sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
 200                                                    sm->own_addr,
 201                                                    ETH_P_RSN_PREAUTH,
 202                                                    rsn_preauth_receive, sm, 0);
 203                 if (sm->l2_preauth_br == NULL) {
 204                         wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
 205                                    "packet processing (bridge) for "
 206                                    "pre-authentication");
 207                         return -2;
 208                 }
 209         }
 210
 211         ctx = os_zalloc(sizeof(*ctx));
 212         if (ctx == NULL) {
 213                 wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
 214                 return -4;
 215         }
 216         ctx->ctx = sm->ctx->ctx;
 217         ctx->msg_ctx = sm->ctx->ctx;
 218         ctx->preauth = 1;
 219         ctx->cb = rsn_preauth_eapol_cb;
 220         ctx->cb_ctx = sm;
 221         ctx->scard_ctx = sm->scard_ctx;
 222         ctx->eapol_send = rsn_preauth_eapol_send;
 223         ctx->eapol_send_ctx = sm;
 224         ctx->set_config_blob = sm->ctx->set_config_blob;
 225         ctx->get_config_blob = sm->ctx->get_config_blob;
 226
 227         sm->preauth_eapol = eapol_sm_init(ctx);
 228         if (sm->preauth_eapol == NULL) {
 229                 os_free(ctx);
 230                 wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
 231                            "state machines for pre-authentication");
 232                 return -3;
 233         }
 234         os_memset(&eapol_conf, 0, sizeof(eapol_conf));
 235         eapol_conf.accept_802_1x_keys = 0;
 236         eapol_conf.required_keys = 0;
 237         eapol_conf.fast_reauth = sm->fast_reauth;
 238         eapol_conf.workaround = sm->eap_workaround;
 239         eapol_sm_notify_config(sm->preauth_eapol, eap_conf, &eapol_conf);
 240         /*
 241          * Use a shorter startPeriod with preauthentication since the first
 242          * preauth EAPOL-Start frame may end up being dropped due to race
 243          * condition in the AP between the data receive and key configuration
 244          * after the 4-Way Handshake.
 245          */
 246         eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
 247         os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
 248
 249         eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
 250         /* 802.1X::portControl = Auto */
 251         eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
 252
 253         eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
 254                                rsn_preauth_timeout, sm, NULL);
 255
 256         return 0;
 257 }
 258
 259
 260 /**
 261  * rsn_preauth_deinit - Abort RSN pre-authentication
 262  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 263  *
 264  * This function aborts the current RSN pre-authentication (if one is started)
 265  * and frees resources allocated for it.
 266  */
 267 void rsn_preauth_deinit(struct wpa_sm *sm)
 268 {
 269         if (sm == NULL || !sm->preauth_eapol)
 270                 return;
 271
 272         eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
 273         eapol_sm_deinit(sm->preauth_eapol);
 274         sm->preauth_eapol = NULL;
 275         os_memset(sm->preauth_bssid, 0, ETH_ALEN);
 276
 277         l2_packet_deinit(sm->l2_preauth);
 278         sm->l2_preauth = NULL;
 279         if (sm->l2_preauth_br) {
 280                 l2_packet_deinit(sm->l2_preauth_br);
 281                 sm->l2_preauth_br = NULL;
 282         }
 283 }
 284
 285
 286 /**
 287  * rsn_preauth_candidate_process - Process PMKSA candidates
 288  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 289  *
 290  * Go through the PMKSA candidates and start pre-authentication if a candidate
 291  * without an existing PMKSA cache entry is found. Processed candidates will be
 292  * removed from the list.
 293  */
 294 void rsn_preauth_candidate_process(struct wpa_sm *sm)
 295 {
 296         struct rsn_pmksa_candidate *candidate;
 297
 298         if (sm->pmksa_candidates == NULL)
 299                 return;
 300
 301         /* TODO: drop priority for old candidate entries */
 302
 303         wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
 304                 "list");
 305         if (sm->preauth_eapol ||
 306             sm->proto != WPA_PROTO_RSN ||
 307             wpa_sm_get_state(sm) != WPA_COMPLETED ||
 308             (sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X &&
 309              sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SHA256)) {
 310                 wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: not in suitable state "
 311                         "for new pre-authentication");
 312                 return; /* invalid state for new pre-auth */
 313         }
 314
 315         while (sm->pmksa_candidates) {
 316                 struct rsn_pmksa_cache_entry *p = NULL;
 317                 candidate = sm->pmksa_candidates;
 318                 p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL);
 319                 if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
 320                     (p == NULL || p->opportunistic)) {
 321                         wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA "
 322                                 "candidate " MACSTR
 323                                 " selected for pre-authentication",
 324                                 MAC2STR(candidate->bssid));
 325                         sm->pmksa_candidates = candidate->next;
 326                         rsn_preauth_init(sm, candidate->bssid,
 327                                          sm->eap_conf_ctx);
 328                         os_free(candidate);
 329                         return;
 330                 }
 331                 wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA candidate "
 332                         MACSTR " does not need pre-authentication anymore",
 333                         MAC2STR(candidate->bssid));
 334                 /* Some drivers (e.g., NDIS) expect to get notified about the
 335                  * PMKIDs again, so report the existing data now. */
 336                 if (p) {
 337                         wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
 338                 }
 339
 340                 sm->pmksa_candidates = candidate->next;
 341                 os_free(candidate);
 342         }
 343         wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
 344                 "candidates");
 345 }
 346
 347
 348 /**
 349  * pmksa_candidate_add - Add a new PMKSA candidate
 350  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 351  * @bssid: BSSID (authenticator address) of the candidate
 352  * @prio: Priority (the smaller number, the higher priority)
 353  * @preauth: Whether the candidate AP advertises support for pre-authentication
 354  *
 355  * This function is used to add PMKSA candidates for RSN pre-authentication. It
 356  * is called from scan result processing and from driver events for PMKSA
 357  * candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
 358  */
 359 void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
 360                          int prio, int preauth)
 361 {
 362         struct rsn_pmksa_candidate *cand, *prev, *pos;
 363
 364         if (sm->network_ctx && sm->proactive_key_caching)
 365                 pmksa_cache_get_opportunistic(sm->pmksa, sm->network_ctx,
 366                                               bssid);
 367
 368         if (!preauth) {
 369                 wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
 370                            "preauth flag");
 371                 return;
 372         }
 373
 374         /* If BSSID already on candidate list, update the priority of the old
 375          * entry. Do not override priority based on normal scan results. */
 376         prev = NULL;
 377         cand = sm->pmksa_candidates;
 378         while (cand) {
 379                 if (os_memcmp(cand->bssid, bssid, ETH_ALEN) == 0) {
 380                         if (prev)
 381                                 prev->next = cand->next;
 382                         else
 383                                 sm->pmksa_candidates = cand->next;
 384                         break;
 385                 }
 386                 prev = cand;
 387                 cand = cand->next;
 388         }
 389
 390         if (cand) {
 391                 if (prio < PMKID_CANDIDATE_PRIO_SCAN)
 392                         cand->priority = prio;
 393         } else {
 394                 cand = os_zalloc(sizeof(*cand));
 395                 if (cand == NULL)
 396                         return;
 397                 os_memcpy(cand->bssid, bssid, ETH_ALEN);
 398                 cand->priority = prio;
 399         }
 400
 401         /* Add candidate to the list; order by increasing priority value. i.e.,
 402          * highest priority (smallest value) first. */
 403         prev = NULL;
 404         pos = sm->pmksa_candidates;
 405         while (pos) {
 406                 if (cand->priority <= pos->priority)
 407                         break;
 408                 prev = pos;
 409                 pos = pos->next;
 410         }
 411         cand->next = pos;
 412         if (prev)
 413                 prev->next = cand;
 414         else
 415                 sm->pmksa_candidates = cand;
 416
 417         wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: added PMKSA cache "
 418                 "candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
 419         rsn_preauth_candidate_process(sm);
 420 }
 421
 422
 423 /* TODO: schedule periodic scans if current AP supports preauth */
 424
 425 /**
 426  * rsn_preauth_scan_results - Process scan results to find PMKSA candidates
 427  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 428  * @results: Scan results
 429  *
 430  * This functions goes through the scan results and adds all suitable APs
 431  * (Authenticators) into PMKSA candidate list.
 432  */
 433 void rsn_preauth_scan_results(struct wpa_sm *sm,
 434                               struct wpa_scan_results *results)
 435 {
 436         struct wpa_scan_res *r;
 437         struct wpa_ie_data ie;
 438         int i;
 439         struct rsn_pmksa_cache_entry *pmksa;
 440
 441         if (sm->ssid_len == 0)
 442                 return;
 443
 444         /*
 445          * TODO: is it ok to free all candidates? What about the entries
 446          * received from EVENT_PMKID_CANDIDATE?
 447          */
 448         pmksa_candidate_free(sm);
 449
 450         for (i = results->num - 1; i >= 0; i--) {
 451                 const u8 *ssid, *rsn;
 452
 453                 r = results->res[i];
 454
 455                 ssid = wpa_scan_get_ie(r, WLAN_EID_SSID);
 456                 if (ssid == NULL || ssid[1] != sm->ssid_len ||
 457                     os_memcmp(ssid + 2, sm->ssid, ssid[1]) != 0)
 458                         continue;
 459
 460                 if (os_memcmp(r->bssid, sm->bssid, ETH_ALEN) == 0)
 461                         continue;
 462
 463                 rsn = wpa_scan_get_ie(r, WLAN_EID_RSN);
 464                 if (rsn == NULL || wpa_parse_wpa_ie(rsn, 2 + rsn[1], &ie))
 465                         continue;
 466
 467                 pmksa = pmksa_cache_get(sm->pmksa, r->bssid, NULL);
 468                 if (pmksa &&
 469                     (!pmksa->opportunistic ||
 470                      !(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
 471                         continue;
 472
 473                 /*
 474                  * Give less priority to candidates found from normal
 475                  * scan results.
 476                  */
 477                 pmksa_candidate_add(sm, r->bssid,
 478                                     PMKID_CANDIDATE_PRIO_SCAN,
 479                                     ie.capabilities & WPA_CAPABILITY_PREAUTH);
 480         }
 481 }
 482
 483
 484 #ifdef CONFIG_CTRL_IFACE
 485 /**
 486  * rsn_preauth_get_status - Get pre-authentication status
 487  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 488  * @buf: Buffer for status information
 489  * @buflen: Maximum buffer length
 490  * @verbose: Whether to include verbose status information
 491  * Returns: Number of bytes written to buf.
 492  *
 493  * Query WPA2 pre-authentication for status information. This function fills in
 494  * a text area with current status information. If the buffer (buf) is not
 495  * large enough, status information will be truncated to fit the buffer.
 496  */
 497 int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
 498                            int verbose)
 499 {
 500         char *pos = buf, *end = buf + buflen;
 501         int res, ret;
 502
 503         if (sm->preauth_eapol) {
 504                 ret = os_snprintf(pos, end - pos, "Pre-authentication "
 505                                   "EAPOL state machines:\n");
 506                 if (ret < 0 || ret >= end - pos)
 507                         return pos - buf;
 508                 pos += ret;
 509                 res = eapol_sm_get_status(sm->preauth_eapol,
 510                                           pos, end - pos, verbose);
 511                 if (res >= 0)
 512                         pos += res;
 513         }
 514
 515         return pos - buf;
 516 }
 517 #endif /* CONFIG_CTRL_IFACE */
 518
 519
 520 /**
 521  * rsn_preauth_in_progress - Verify whether pre-authentication is in progress
 522  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 523  */
 524 int rsn_preauth_in_progress(struct wpa_sm *sm)
 525 {
 526         return sm->preauth_eapol != NULL;
 527 }
 528
 529 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */