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