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