src/rsn_supp/pmksa_cache.c

   1 /*
   2  * WPA Supplicant - RSN PMKSA cache
   3  * Copyright (c) 2004-2006, 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 "eloop.h"
  20 #include "sha1.h"
  21 #include "wpa_i.h"
  22 #include "eapol_supp/eapol_supp_sm.h"
  23 #include "pmksa_cache.h"
  24
  25 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
  26
  27 static const int pmksa_cache_max_entries = 32;
  28
  29 struct rsn_pmksa_cache {
  30         struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */
  31         int pmksa_count; /* number of entries in PMKSA cache */
  32         struct wpa_sm *sm; /* TODO: get rid of this reference(?) */
  33
  34         void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx,
  35                         int replace);
  36         void *ctx;
  37 };
  38
  39
  40 /**
  41  * rsn_pmkid - Calculate PMK identifier
  42  * @pmk: Pairwise master key
  43  * @pmk_len: Length of pmk in bytes
  44  * @aa: Authenticator address
  45  * @spa: Supplicant address
  46  *
  47  * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
  48  * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
  49  */
  50 void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa,
  51                u8 *pmkid)
  52 {
  53         char *title = "PMK Name";
  54         const u8 *addr[3];
  55         const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
  56         unsigned char hash[SHA1_MAC_LEN];
  57
  58         addr[0] = (u8 *) title;
  59         addr[1] = aa;
  60         addr[2] = spa;
  61
  62         hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
  63         os_memcpy(pmkid, hash, PMKID_LEN);
  64 }
  65
  66
  67 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
  68
  69
  70 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
  71 {
  72         os_free(entry);
  73 }
  74
  75
  76 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
  77                                    struct rsn_pmksa_cache_entry *entry,
  78                                    int replace)
  79 {
  80         pmksa->pmksa_count--;
  81         pmksa->free_cb(entry, pmksa->ctx, replace);
  82         _pmksa_cache_free_entry(entry);
  83 }
  84
  85
  86 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
  87 {
  88         struct rsn_pmksa_cache *pmksa = eloop_ctx;
  89         struct os_time now;
  90
  91         os_get_time(&now);
  92         while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
  93                 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
  94                 pmksa->pmksa = entry->next;
  95                 wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
  96                            MACSTR, MAC2STR(entry->aa));
  97                 pmksa_cache_free_entry(pmksa, entry, 0);
  98         }
  99
 100         pmksa_cache_set_expiration(pmksa);
 101 }
 102
 103
 104 static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx)
 105 {
 106         struct rsn_pmksa_cache *pmksa = eloop_ctx;
 107         pmksa->sm->cur_pmksa = NULL;
 108         eapol_sm_request_reauth(pmksa->sm->eapol);
 109 }
 110
 111
 112 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
 113 {
 114         int sec;
 115         struct rsn_pmksa_cache_entry *entry;
 116         struct os_time now;
 117
 118         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 119         eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL);
 120         if (pmksa->pmksa == NULL)
 121                 return;
 122         os_get_time(&now);
 123         sec = pmksa->pmksa->expiration - now.sec;
 124         if (sec < 0)
 125                 sec = 0;
 126         eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
 127
 128         entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa :
 129                 pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL);
 130         if (entry) {
 131                 sec = pmksa->pmksa->reauth_time - now.sec;
 132                 if (sec < 0)
 133                         sec = 0;
 134                 eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa,
 135                                        NULL);
 136         }
 137 }
 138
 139
 140 /**
 141  * pmksa_cache_add - Add a PMKSA cache entry
 142  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 143  * @pmk: The new pairwise master key
 144  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
 145  * @aa: Authenticator address
 146  * @spa: Supplicant address
 147  * @network_ctx: Network configuration context for this PMK
 148  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
 149  *
 150  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
 151  * cache. If an old entry is already in the cache for the same Authenticator,
 152  * this entry will be replaced with the new entry. PMKID will be calculated
 153  * based on the PMK and the driver interface is notified of the new PMKID.
 154  */
 155 struct rsn_pmksa_cache_entry *
 156 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
 157                 const u8 *aa, const u8 *spa, void *network_ctx)
 158 {
 159         struct rsn_pmksa_cache_entry *entry, *pos, *prev;
 160         struct os_time now;
 161
 162         if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN)
 163                 return NULL;
 164
 165         entry = os_zalloc(sizeof(*entry));
 166         if (entry == NULL)
 167                 return NULL;
 168         os_memcpy(entry->pmk, pmk, pmk_len);
 169         entry->pmk_len = pmk_len;
 170         rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
 171         os_get_time(&now);
 172         entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime;
 173         entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime *
 174                 pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100;
 175         entry->akmp = WPA_KEY_MGMT_IEEE8021X;
 176         os_memcpy(entry->aa, aa, ETH_ALEN);
 177         entry->network_ctx = network_ctx;
 178
 179         /* Replace an old entry for the same Authenticator (if found) with the
 180          * new entry */
 181         pos = pmksa->pmksa;
 182         prev = NULL;
 183         while (pos) {
 184                 if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) {
 185                         if (pos->pmk_len == pmk_len &&
 186                             os_memcmp(pos->pmk, pmk, pmk_len) == 0 &&
 187                             os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) ==
 188                             0) {
 189                                 wpa_printf(MSG_DEBUG, "WPA: reusing previous "
 190                                            "PMKSA entry");
 191                                 os_free(entry);
 192                                 return pos;
 193                         }
 194                         if (prev == NULL)
 195                                 pmksa->pmksa = pos->next;
 196                         else
 197                                 prev->next = pos->next;
 198                         if (pos == pmksa->sm->cur_pmksa) {
 199                                 /* We are about to replace the current PMKSA
 200                                  * cache entry. This happens when the PMKSA
 201                                  * caching attempt fails, so we don't want to
 202                                  * force pmksa_cache_free_entry() to disconnect
 203                                  * at this point. Let's just make sure the old
 204                                  * PMKSA cache entry will not be used in the
 205                                  * future.
 206                                  */
 207                                 wpa_printf(MSG_DEBUG, "RSN: replacing current "
 208                                            "PMKSA entry");
 209                                 pmksa->sm->cur_pmksa = NULL;
 210                         }
 211                         wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for "
 212                                    "the current AP");
 213                         pmksa_cache_free_entry(pmksa, pos, 1);
 214                         break;
 215                 }
 216                 prev = pos;
 217                 pos = pos->next;
 218         }
 219
 220         if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
 221                 /* Remove the oldest entry to make room for the new entry */
 222                 pos = pmksa->pmksa;
 223                 pmksa->pmksa = pos->next;
 224                 wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
 225                            "entry (for " MACSTR ") to make room for new one",
 226                            MAC2STR(pos->aa));
 227                 wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid);
 228                 pmksa_cache_free_entry(pmksa, pos, 0);
 229         }
 230
 231         /* Add the new entry; order by expiration time */
 232         pos = pmksa->pmksa;
 233         prev = NULL;
 234         while (pos) {
 235                 if (pos->expiration > entry->expiration)
 236                         break;
 237                 prev = pos;
 238                 pos = pos->next;
 239         }
 240         if (prev == NULL) {
 241                 entry->next = pmksa->pmksa;
 242                 pmksa->pmksa = entry;
 243                 pmksa_cache_set_expiration(pmksa);
 244         } else {
 245                 entry->next = prev->next;
 246                 prev->next = entry;
 247         }
 248         pmksa->pmksa_count++;
 249         wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
 250                    MAC2STR(entry->aa));
 251         wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid);
 252
 253         return entry;
 254 }
 255
 256
 257 /**
 258  * pmksa_cache_deinit - Free all entries in PMKSA cache
 259  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 260  */
 261 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
 262 {
 263         struct rsn_pmksa_cache_entry *entry, *prev;
 264
 265         if (pmksa == NULL)
 266                 return;
 267
 268         entry = pmksa->pmksa;
 269         pmksa->pmksa = NULL;
 270         while (entry) {
 271                 prev = entry;
 272                 entry = entry->next;
 273                 os_free(prev);
 274         }
 275         pmksa_cache_set_expiration(pmksa);
 276         os_free(pmksa);
 277 }
 278
 279
 280 /**
 281  * pmksa_cache_get - Fetch a PMKSA cache entry
 282  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 283  * @aa: Authenticator address or %NULL to match any
 284  * @pmkid: PMKID or %NULL to match any
 285  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
 286  */
 287 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
 288                                                const u8 *aa, const u8 *pmkid)
 289 {
 290         struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 291         while (entry) {
 292                 if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) &&
 293                     (pmkid == NULL ||
 294                      os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
 295                         return entry;
 296                 entry = entry->next;
 297         }
 298         return NULL;
 299 }
 300
 301
 302 /**
 303  * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache
 304  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 305  *
 306  * Clear references to old data structures when wpa_supplicant is reconfigured.
 307  */
 308 void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa)
 309 {
 310         struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 311         while (entry) {
 312                 entry->network_ctx = NULL;
 313                 entry = entry->next;
 314         }
 315 }
 316
 317
 318 static struct rsn_pmksa_cache_entry *
 319 pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa,
 320                         const struct rsn_pmksa_cache_entry *old_entry,
 321                         const u8 *aa)
 322 {
 323         struct rsn_pmksa_cache_entry *new_entry;
 324
 325         new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len,
 326                                     aa, pmksa->sm->own_addr,
 327                                     old_entry->network_ctx);
 328         if (new_entry == NULL)
 329                 return NULL;
 330
 331         /* TODO: reorder entries based on expiration time? */
 332         new_entry->expiration = old_entry->expiration;
 333         new_entry->opportunistic = 1;
 334
 335         return new_entry;
 336 }
 337
 338
 339 /**
 340  * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry
 341  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 342  * @network_ctx: Network configuration context
 343  * @aa: Authenticator address for the new AP
 344  * Returns: Pointer to a new PMKSA cache entry or %NULL if not available
 345  *
 346  * Try to create a new PMKSA cache entry opportunistically by guessing that the
 347  * new AP is sharing the same PMK as another AP that has the same SSID and has
 348  * already an entry in PMKSA cache.
 349  */
 350 struct rsn_pmksa_cache_entry *
 351 pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, void *network_ctx,
 352                               const u8 *aa)
 353 {
 354         struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 355
 356         if (network_ctx == NULL)
 357                 return NULL;
 358         while (entry) {
 359                 if (entry->network_ctx == network_ctx) {
 360                         entry = pmksa_cache_clone_entry(pmksa, entry, aa);
 361                         if (entry) {
 362                                 wpa_printf(MSG_DEBUG, "RSN: added "
 363                                            "opportunistic PMKSA cache entry "
 364                                            "for " MACSTR, MAC2STR(aa));
 365                         }
 366                         return entry;
 367                 }
 368                 entry = entry->next;
 369         }
 370         return NULL;
 371 }
 372
 373
 374 /**
 375  * pmksa_cache_get_current - Get the current used PMKSA entry
 376  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 377  * Returns: Pointer to the current PMKSA cache entry or %NULL if not available
 378  */
 379 struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm)
 380 {
 381         if (sm == NULL)
 382                 return NULL;
 383         return sm->cur_pmksa;
 384 }
 385
 386
 387 /**
 388  * pmksa_cache_clear_current - Clear the current PMKSA entry selection
 389  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 390  */
 391 void pmksa_cache_clear_current(struct wpa_sm *sm)
 392 {
 393         if (sm == NULL)
 394                 return;
 395         sm->cur_pmksa = NULL;
 396 }
 397
 398
 399 /**
 400  * pmksa_cache_set_current - Set the current PMKSA entry selection
 401  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 402  * @pmkid: PMKID for selecting PMKSA or %NULL if not used
 403  * @bssid: BSSID for PMKSA or %NULL if not used
 404  * @network_ctx: Network configuration context
 405  * @try_opportunistic: Whether to allow opportunistic PMKSA caching
 406  * Returns: 0 if PMKSA was found or -1 if no matching entry was found
 407  */
 408 int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid,
 409                             const u8 *bssid, void *network_ctx,
 410                             int try_opportunistic)
 411 {
 412         struct rsn_pmksa_cache *pmksa = sm->pmksa;
 413         sm->cur_pmksa = NULL;
 414         if (pmkid)
 415                 sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid);
 416         if (sm->cur_pmksa == NULL && bssid)
 417                 sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL);
 418         if (sm->cur_pmksa == NULL && try_opportunistic && bssid)
 419                 sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa,
 420                                                               network_ctx,
 421                                                               bssid);
 422         if (sm->cur_pmksa) {
 423                 wpa_hexdump(MSG_DEBUG, "RSN: PMKID",
 424                             sm->cur_pmksa->pmkid, PMKID_LEN);
 425                 return 0;
 426         }
 427         return -1;
 428 }
 429
 430
 431 /**
 432  * pmksa_cache_list - Dump text list of entries in PMKSA cache
 433  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 434  * @buf: Buffer for the list
 435  * @len: Length of the buffer
 436  * Returns: number of bytes written to buffer
 437  *
 438  * This function is used to generate a text format representation of the
 439  * current PMKSA cache contents for the ctrl_iface PMKSA command.
 440  */
 441 int pmksa_cache_list(struct wpa_sm *sm, char *buf, size_t len)
 442 {
 443         int i, ret;
 444         char *pos = buf;
 445         struct rsn_pmksa_cache_entry *entry;
 446         struct os_time now;
 447
 448         os_get_time(&now);
 449         ret = os_snprintf(pos, buf + len - pos,
 450                           "Index / AA / PMKID / expiration (in seconds) / "
 451                           "opportunistic\n");
 452         if (ret < 0 || ret >= buf + len - pos)
 453                 return pos - buf;
 454         pos += ret;
 455         i = 0;
 456         entry = sm->pmksa->pmksa;
 457         while (entry) {
 458                 i++;
 459                 ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ",
 460                                   i, MAC2STR(entry->aa));
 461                 if (ret < 0 || ret >= buf + len - pos)
 462                         return pos - buf;
 463                 pos += ret;
 464                 pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid,
 465                                         PMKID_LEN);
 466                 ret = os_snprintf(pos, buf + len - pos, " %d %d\n",
 467                                   (int) (entry->expiration - now.sec),
 468                                   entry->opportunistic);
 469                 if (ret < 0 || ret >= buf + len - pos)
 470                         return pos - buf;
 471                 pos += ret;
 472                 entry = entry->next;
 473         }
 474         return pos - buf;
 475 }
 476
 477
 478 /**
 479  * pmksa_cache_init - Initialize PMKSA cache
 480  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
 481  * @ctx: Context pointer for free_cb function
 482  * @sm: Pointer to WPA state machine data from wpa_sm_init()
 483  * Returns: Pointer to PMKSA cache data or %NULL on failure
 484  */
 485 struct rsn_pmksa_cache *
 486 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
 487                                  void *ctx, int replace),
 488                  void *ctx, struct wpa_sm *sm)
 489 {
 490         struct rsn_pmksa_cache *pmksa;
 491
 492         pmksa = os_zalloc(sizeof(*pmksa));
 493         if (pmksa) {
 494                 pmksa->free_cb = free_cb;
 495                 pmksa->ctx = ctx;
 496                 pmksa->sm = sm;
 497         }
 498
 499         return pmksa;
 500 }
 501
 502 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */