src/rsn_supp/pmksa_cache.c

   1 /*
   2  * WPA Supplicant - RSN PMKSA cache
   3  * Copyright (c) 2004-2008, 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 "eloop.h"
  19 #include "eapol_supp/eapol_supp_sm.h"
  20 #include "wpa.h"
  21 #include "wpa_i.h"
  22 #include "pmksa_cache.h"
  23
  24 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
  25
  26 static const int pmksa_cache_max_entries = 32;
  27
  28 struct rsn_pmksa_cache {
  29         struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
  30         int pmksa_count; /* number of entries in PMKSA cache */
  31         struct wpa_sm *sm; /* TODO: get rid of this reference(?) */
  32
  33         void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
  34                         int replace);
  35         void *ctx;
  36 };
  37
  38
  39 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
  40
  41
  42 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
  43 {
  44         os_free(entry);
  45 }
  46
  47
  48 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
  49                                    struct rsn_pmksa_cache_entry *entry,
  50                                    int replace)
  51 {
  52         pmksa->pmksa_count--;
  53         pmksa->free_cb(entry, pmksa->ctx, replace);
  54         _pmksa_cache_free_entry(entry);
  55 }
  56
  57
  58 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
  59 {
  60         struct rsn_pmksa_cache *pmksa = eloop_ctx;
  61         struct os_time now;
  62
  63         os_get_time(&now);
  64         while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
  65                 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
  66                 pmksa->pmksa = entry->next;
  67                 wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
  68                            MACSTR, MAC2STR(entry->aa));
  69                 wpa_sm_remove_pmkid(pmksa->sm, entry->aa, entry->pmkid);
  70                 pmksa_cache_free_entry(pmksa, entry, 0);
  71         }
  72
  73         pmksa_cache_set_expiration(pmksa);
  74 }
  75
  76
  77 static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
  78 {
  79         struct rsn_pmksa_cache *pmksa = eloop_ctx;
  80         pmksa->sm->cur_pmksa = NULL;
  81         eapol_sm_request_reauth(pmksa->sm->eapol);
  82 }
  83
  84
  85 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
  86 {
  87         int sec;
  88         struct rsn_pmksa_cache_entry *entry;
  89         struct os_time now;
  90
  91         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
  92         eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
  93         if (pmksa->pmksa == NULL)
  94                 return;
  95         os_get_time(&now);
  96         sec = pmksa->pmksa->expiration - now.sec;
  97         if (sec < 0)
  98                 sec = 0;
  99         eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
 100
 101         entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
 102                 pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
 103         if (entry) {
 104                 sec = pmksa->pmksa->reauth_time - now.sec;
 105                 if (sec < 0)
 106                         sec = 0;
 107                 eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
 108                                        NULL);
 109         }
 110 }
 111
 112
 113 /**
 114  * pmksa_cache_add - Add a PMKSA cache entry
 115  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 116  * @pmk: The new pairwise master key
 117  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
 118  * @aa: Authenticator address
 119  * @spa: Supplicant address
 120  * @network_ctx: Network configuration context for this PMK
 121  * @akmp: WPA_KEY_MGMT_* used in key derivation
 122  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
 123  *
 124  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
 125  * cache. If an old entry is already in the cache for the same Authenticator,
 126  * this entry will be replaced with the new entry. PMKID will be calculated
 127  * based on the PMK and the driver interface is notified of the new PMKID.
 128  */
 129 struct rsn_pmksa_cache_entry *
 130 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
 131                 const u8 *aa, const u8 *spa, void *network_ctx, int akmp)
 132 {
 133         struct rsn_pmksa_cache_entry *entry, *pos, *prev;
 134         struct os_time now;
 135
 136         if (pmk_len > PMK_LEN)
 137                 return NULL;
 138
 139         entry = os_zalloc(sizeof(*entry));
 140         if (entry == NULL)
 141                 return NULL;
 142         os_memcpy(entry->pmk, pmk, pmk_len);
 143         entry->pmk_len = pmk_len;
 144         rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid,
 145                   wpa_key_mgmt_sha256(akmp));
 146         os_get_time(&now);
 147         entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
 148         entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
 149                 pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
 150         entry->akmp = akmp;
 151         os_memcpy(entry->aa, aa, ETH_ALEN);
 152         entry->network_ctx = network_ctx;
 153
 154         /* Replace an old entry for the same Authenticator (if found) with the
 155          * new entry */
 156         pos = pmksa->pmksa;
 157         prev = NULL;
 158         while (pos) {
 159                 if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
 160                         if (pos->pmk_len == pmk_len &&
 161                             os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
 162                             os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
 163                             0) {
 164                                 wpa_printf(MSG_DEBUG, "WPA: reusing previous "
 165                                            "PMKSA entry");
 166                                 os_free(entry);
 167                                 return pos;
 168                         }
 169                         if (prev == NULL)
 170                                 pmksa->pmksa = pos->next;
 171                         else
 172                                 prev->next = pos->next;
 173                         if (pos == pmksa->sm->cur_pmksa) {
 174                                 /* We are about to replace the current PMKSA
 175                                  * cache entry. This happens when the PMKSA
 176                                  * caching attempt fails, so we don't want to
 177                                  * force pmksa_cache_free_entry() to disconnect
 178                                  * at this point. Let's just make sure the old
 179                                  * PMKSA cache entry will not be used in the
 180                                  * future.
 181                                  */
 182                                 wpa_printf(MSG_DEBUG, "RSN: replacing current "
 183                                            "PMKSA entry");
 184                                 pmksa->sm->cur_pmksa = NULL;
 185                         }
 186                         wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
 187                                    "the current AP");
 188                         pmksa_cache_free_entry(pmksa, pos, 1);
 189                         break;
 190                 }
 191                 prev = pos;
 192                 pos = pos->next;
 193         }
 194
 195         if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
 196                 /* Remove the oldest entry to make room for the new entry */
 197                 pos = pmksa->pmksa;
 198                 pmksa->pmksa = pos->next;
 199                 wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
 200                            "entry (for " MACSTR ") to make room for new one",
 201                            MAC2STR(pos->aa));
 202                 wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
 203                 pmksa_cache_free_entry(pmksa, pos, 0);
 204         }
 205
 206         /* Add the new entry; order by expiration time */
 207         pos = pmksa->pmksa;
 208         prev = NULL;
 209         while (pos) {
 210                 if (pos->expiration > entry->expiration)
 211                         break;
 212                 prev = pos;
 213                 pos = pos->next;
 214         }
 215         if (prev == NULL) {
 216                 entry->next = pmksa->pmksa;
 217                 pmksa->pmksa = entry;
 218                 pmksa_cache_set_expiration(pmksa);
 219         } else {
 220                 entry->next = prev->next;
 221                 prev->next = entry;
 222         }
 223         pmksa->pmksa_count++;
 224         wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
 225                    MAC2STR(entry->aa));
 226         wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
 227
 228         return entry;
 229 }
 230
 231
 232 /**
 233  * pmksa_cache_flush - Flush PMKSA cache entries for a specific network
 234  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 235  * @network_ctx: Network configuration context or %NULL to flush all entries
 236  */
 237 void pmksa_cache_flush(struct rsn_pmksa_cache *pmksa, void *network_ctx)
 238 {
 239         struct rsn_pmksa_cache_entry *entry, *prev = NULL, *tmp;
 240         int removed = 0;
 241
 242         entry = pmksa->pmksa;
 243         while (entry) {
 244                 if (entry->network_ctx == network_ctx || network_ctx == NULL) {
 245                         wpa_printf(MSG_DEBUG, "RSN: Flush PMKSA cache entry "
 246                                    "for " MACSTR, MAC2STR(entry->aa));
 247                         if (prev)
 248                                 prev->next = entry->next;
 249                         else
 250                                 pmksa->pmksa = entry->next;
 251                         tmp = entry;
 252                         entry = entry->next;
 253                         wpa_sm_remove_pmkid(pmksa->sm, tmp->aa, tmp->pmkid);
 254                         pmksa_cache_free_entry(pmksa, tmp, 0);
 255                         removed++;
 256                 } else {
 257                         prev = entry;
 258                         entry = entry->next;
 259                 }
 260         }
 261         if (removed)
 262                 pmksa_cache_set_expiration(pmksa);
 263 }
 264
 265
 266 /**
 267  * pmksa_cache_deinit - Free all entries in PMKSA cache
 268  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 269  */
 270 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
 271 {
 272         struct rsn_pmksa_cache_entry *entry, *prev;
 273
 274         if (pmksa == NULL)
 275                 return;
 276
 277         entry = pmksa->pmksa;
 278         pmksa->pmksa = NULL;
 279         while (entry) {
 280                 prev = entry;
 281                 entry = entry->next;
 282                 os_free(prev);
 283         }
 284         pmksa_cache_set_expiration(pmksa);
 285         os_free(pmksa);
 286 }
 287
 288
 289 /**
 290  * pmksa_cache_get - Fetch a PMKSA cache entry
 291  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 292  * @aa: Authenticator address or %NULL to match any
 293  * @pmkid: PMKID or %NULL to match any
 294  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
 295  */
 296 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
 297                                                const u8 *aa, const u8 *pmkid)
 298 {
 299         struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 300         while (entry) {
 301                 if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
 302                     (pmkid == NULL ||
 303                      os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
 304                         return entry;
 305                 entry = entry->next;
 306         }
 307         return NULL;
 308 }
 309
 310
 311 static struct rsn_pmksa_cache_entry *
 312 pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
 313                         const struct rsn_pmksa_cache_entry *old_entry,
 314                         const u8 *aa)
 315 {
 316         struct rsn_pmksa_cache_entry *new_entry;
 317
 318         new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
 319                                     aa, pmksa->sm->own_addr,
 320                                     old_entry->network_ctx, old_entry->akmp);
 321         if (new_entry == NULL)
 322                 return NULL;
 323
 324         /* TODO: reorder entries based on expiration time? */
 325         new_entry->expiration = old_entry->expiration;
 326         new_entry->opportunistic = 1;
 327
 328         return new_entry;
 329 }
 330
 331
 332 /**
 333  * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
 334  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 335  * @network_ctx: Network configuration context
 336  * @aa: Authenticator address for the new AP
 337  * Returns: Pointer to a new PMKSA cache entry or %NULL if not available
 338  *
 339  * Try to create a new PMKSA cache entry opportunistically by guessing that the
 340  * new AP is sharing the same PMK as another AP that has the same SSID and has
 341  * already an entry in PMKSA cache.
 342  */
 343 struct rsn_pmksa_cache_entry *
 344 pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, void *network_ctx,
 345                               const u8 *aa)
 346 {
 347         struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 348
 349         wpa_printf(MSG_DEBUG, "RSN: Consider " MACSTR " for OKC", MAC2STR(aa));
 350         if (network_ctx == NULL)
 351                 return NULL;
 352         while (entry) {
 353                 if (entry->network_ctx == network_ctx) {
 354                         entry = pmksa_cache_clone_entry(pmksa, entry, aa);
 355                         if (entry) {
 356                                 wpa_printf(MSG_DEBUG, "RSN: added "
 357                                            "opportunistic PMKSA cache entry "
 358                                            "for " MACSTR, MAC2STR(aa));
 359                         }
 360                         return entry;
 361                 }
 362                 entry = entry->next;
 363         }
 364         return NULL;
 365 }
 366
 367
 368 /**
 369  * pmksa_cache_get_current - Get the current used PMKSA entry
 370  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 371  * Returns: Pointer to the current PMKSA cache entry or %NULL if not available
 372  */
 373 struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
 374 {
 375         if (sm == NULL)
 376                 return NULL;
 377         return sm->cur_pmksa;
 378 }
 379
 380
 381 /**
 382  * pmksa_cache_clear_current - Clear the current PMKSA entry selection
 383  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 384  */
 385 void pmksa_cache_clear_current(struct wpa_sm *sm)
 386 {
 387         if (sm == NULL)
 388                 return;
 389         sm->cur_pmksa = NULL;
 390 }
 391
 392
 393 /**
 394  * pmksa_cache_set_current - Set the current PMKSA entry selection
 395  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 396  * @pmkid: PMKID for selecting PMKSA or %NULL if not used
 397  * @bssid: BSSID for PMKSA or %NULL if not used
 398  * @network_ctx: Network configuration context
 399  * @try_opportunistic: Whether to allow opportunistic PMKSA caching
 400  * Returns: 0 if PMKSA was found or -1 if no matching entry was found
 401  */
 402 int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
 403                             const u8 *bssid, void *network_ctx,
 404                             int try_opportunistic)
 405 {
 406         struct rsn_pmksa_cache *pmksa = sm->pmksa;
 407         sm->cur_pmksa = NULL;
 408         if (pmkid)
 409                 sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
 410         if (sm->cur_pmksa == NULL && bssid)
 411                 sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
 412         if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
 413                 sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa,
 414                                                               network_ctx,
 415                                                               bssid);
 416         if (sm->cur_pmksa) {
 417                 wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
 418                             sm->cur_pmksa->pmkid, PMKID_LEN);
 419                 return 0;
 420         }
 421         return -1;
 422 }
 423
 424
 425 /**
 426  * pmksa_cache_list - Dump text list of entries in PMKSA cache
 427  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 428  * @buf: Buffer for the list
 429  * @len: Length of the buffer
 430  * Returns: number of bytes written to buffer
 431  *
 432  * This function is used to generate a text format representation of the
 433  * current PMKSA cache contents for the ctrl_iface PMKSA command.
 434  */
 435 int pmksa_cache_list(struct rsn_pmksa_cache *pmksa, char *buf, size_t len)
 436 {
 437         int i, ret;
 438         char *pos = buf;
 439         struct rsn_pmksa_cache_entry *entry;
 440         struct os_time now;
 441
 442         os_get_time(&now);
 443         ret = os_snprintf(pos, buf + len - pos,
 444                           "Index / AA / PMKID / expiration (in seconds) / "
 445                           "opportunistic\n");
 446         if (ret < 0 || ret >= buf + len - pos)
 447                 return pos - buf;
 448         pos += ret;
 449         i = 0;
 450         entry = pmksa->pmksa;
 451         while (entry) {
 452                 i++;
 453                 ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
 454                                   i, MAC2STR(entry->aa));
 455                 if (ret < 0 || ret >= buf + len - pos)
 456                         return pos - buf;
 457                 pos += ret;
 458                 pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
 459                                         PMKID_LEN);
 460                 ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
 461                                   (int) (entry->expiration - now.sec),
 462                                   entry->opportunistic);
 463                 if (ret < 0 || ret >= buf + len - pos)
 464                         return pos - buf;
 465                 pos += ret;
 466                 entry = entry->next;
 467         }
 468         return pos - buf;
 469 }
 470
 471
 472 /**
 473  * pmksa_cache_init - Initialize PMKSA cache
 474  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
 475  * @ctx: Context pointer for free_cb function
 476  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 477  * Returns: Pointer to PMKSA cache data or %NULL on failure
 478  */
 479 struct rsn_pmksa_cache *
 480 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
 481                                  void *ctx, int replace),
 482                  void *ctx, struct wpa_sm *sm)
 483 {
 484         struct rsn_pmksa_cache *pmksa;
 485
 486         pmksa = os_zalloc(sizeof(*pmksa));
 487         if (pmksa) {
 488                 pmksa->free_cb = free_cb;
 489                 pmksa->ctx = ctx;
 490                 pmksa->sm = sm;
 491         }
 492
 493         return pmksa;
 494 }
 495
 496 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */