1 /* 2 * WPA Supplicant - RSN PMKSA cache 3 * Copyright (c) 2004-2006, Jouni Malinen <j (at) 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 "config_ssid.h" 21 #include "sha1.h" 22 #include "wpa_i.h" 23 #include "l2_packet.h" 24 #include "eapol_sm.h" 25 #include "pmksa_cache.h" 26 27 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2) 28 29 static const int pmksa_cache_max_entries = 32; 30 31 struct rsn_pmksa_cache { 32 struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */ 33 int pmksa_count; /* number of entries in PMKSA cache */ 34 struct wpa_sm *sm; /* TODO: get rid of this reference(?) */ 35 36 void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx, 37 int replace); 38 void *ctx; 39 }; 40 41 42 /** 43 * rsn_pmkid - Calculate PMK identifier 44 * @pmk: Pairwise master key 45 * @pmk_len: Length of pmk in bytes 46 * @aa: Authenticator address 47 * @spa: Supplicant address 48 * 49 * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy 50 * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA) 51 */ 52 static void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, 53 const u8 *spa, u8 *pmkid) 54 { 55 char *title = "PMK Name"; 56 const u8 *addr[3]; 57 const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN }; 58 unsigned char hash[SHA1_MAC_LEN]; 59 60 addr[0] = (u8 *) title; 61 addr[1] = aa; 62 addr[2] = spa; 63 64 hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash); 65 os_memcpy(pmkid, hash, PMKID_LEN); 66 } 67 68 69 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa); 70 71 72 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry) 73 { 74 os_free(entry); 75 } 76 77 78 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa, 79 struct rsn_pmksa_cache_entry *entry, 80 int replace) 81 { 82 pmksa->pmksa_count--; 83 pmksa->free_cb(entry, pmksa->ctx, replace); 84 _pmksa_cache_free_entry(entry); 85 } 86 87 88 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx) 89 { 90 struct rsn_pmksa_cache *pmksa = eloop_ctx; 91 struct os_time now; 92 93 os_get_time(&now); 94 while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) { 95 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; 96 pmksa->pmksa = entry->next; 97 wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for " 98 MACSTR, MAC2STR(entry->aa)); 99 pmksa_cache_free_entry(pmksa, entry, 0); 100 } 101 102 pmksa_cache_set_expiration(pmksa); 103 } 104 105 106 static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx) 107 { 108 struct rsn_pmksa_cache *pmksa = eloop_ctx; 109 pmksa->sm->cur_pmksa = NULL; 110 eapol_sm_request_reauth(pmksa->sm->eapol); 111 } 112 113 114 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa) 115 { 116 int sec; 117 struct rsn_pmksa_cache_entry *entry; 118 struct os_time now; 119 120 eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL); 121 eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL); 122 if (pmksa->pmksa == NULL) 123 return; 124 os_get_time(&now); 125 sec = pmksa->pmksa->expiration - now.sec; 126 if (sec < 0) 127 sec = 0; 128 eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL); 129 130 entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa : 131 pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL); 132 if (entry) { 133 sec = pmksa->pmksa->reauth_time - now.sec; 134 if (sec < 0) 135 sec = 0; 136 eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa, 137 NULL); 138 } 139 } 140 141 142 /** 143 * pmksa_cache_add - Add a PMKSA cache entry 144 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() 145 * @pmk: The new pairwise master key 146 * @pmk_len: PMK length in bytes, usually PMK_LEN (32) 147 * @aa: Authenticator address 148 * @spa: Supplicant address 149 * @ssid: The network configuration for which this PMK is being added 150 * Returns: Pointer to the added PMKSA cache entry or %NULL on error 151 * 152 * This function create a PMKSA entry for a new PMK and adds it to the PMKSA 153 * cache. If an old entry is already in the cache for the same Authenticator, 154 * this entry will be replaced with the new entry. PMKID will be calculated 155 * based on the PMK and the driver interface is notified of the new PMKID. 156 */ 157 struct rsn_pmksa_cache_entry * 158 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len, 159 const u8 *aa, const u8 *spa, struct wpa_ssid *ssid) 160 { 161 struct rsn_pmksa_cache_entry *entry, *pos, *prev; 162 struct os_time now; 163 164 if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN) 165 return NULL; 166 167 entry = os_zalloc(sizeof(*entry)); 168 if (entry == NULL) 169 return NULL; 170 os_memcpy(entry->pmk, pmk, pmk_len); 171 entry->pmk_len = pmk_len; 172 rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid); 173 os_get_time(&now); 174 entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime; 175 entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime * 176 pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100; 177 entry->akmp = WPA_KEY_MGMT_IEEE8021X; 178 os_memcpy(entry->aa, aa, ETH_ALEN); 179 entry->ssid = ssid; 180 181 /* Replace an old entry for the same Authenticator (if found) with the 182 * new entry */ 183 pos = pmksa->pmksa; 184 prev = NULL; 185 while (pos) { 186 if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) { 187 if (pos->pmk_len == pmk_len && 188 os_memcmp(pos->pmk, pmk, pmk_len) == 0 && 189 os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) == 190 0) { 191 wpa_printf(MSG_DEBUG, "WPA: reusing previous " 192 "PMKSA entry"); 193 os_free(entry); 194 return pos; 195 } 196 if (prev == NULL) 197 pmksa->pmksa = pos->next; 198 else 199 prev->next = pos->next; 200 if (pos == pmksa->sm->cur_pmksa) { 201 /* We are about to replace the current PMKSA 202 * cache entry. This happens when the PMKSA 203 * caching attempt fails, so we don't want to 204 * force pmksa_cache_free_entry() to disconnect 205 * at this point. Let's just make sure the old 206 * PMKSA cache entry will not be used in the 207 * future. 208 */ 209 wpa_printf(MSG_DEBUG, "RSN: replacing current " 210 "PMKSA entry"); 211 pmksa->sm->cur_pmksa = NULL; 212 } 213 wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for " 214 "the current AP"); 215 pmksa_cache_free_entry(pmksa, pos, 1); 216 break; 217 } 218 prev = pos; 219 pos = pos->next; 220 } 221 222 if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) { 223 /* Remove the oldest entry to make room for the new entry */ 224 pos = pmksa->pmksa; 225 pmksa->pmksa = pos->next; 226 wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache " 227 "entry (for " MACSTR ") to make room for new one", 228 MAC2STR(pos->aa)); 229 wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid); 230 pmksa_cache_free_entry(pmksa, pos, 0); 231 } 232 233 /* Add the new entry; order by expiration time */ 234 pos = pmksa->pmksa; 235 prev = NULL; 236 while (pos) { 237 if (pos->expiration > entry->expiration) 238 break; 239 prev = pos; 240 pos = pos->next; 241 } 242 if (prev == NULL) { 243 entry->next = pmksa->pmksa; 244 pmksa->pmksa = entry; 245 pmksa_cache_set_expiration(pmksa); 246 } else { 247 entry->next = prev->next; 248 prev->next = entry; 249 } 250 pmksa->pmksa_count++; 251 wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR, 252 MAC2STR(entry->aa)); 253 wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid); 254 255 return entry; 256 } 257 258 259 /** 260 * pmksa_cache_deinit - Free all entries in PMKSA cache 261 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() 262 */ 263 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa) 264 { 265 struct rsn_pmksa_cache_entry *entry, *prev; 266 267 if (pmksa == NULL) 268 return; 269 270 entry = pmksa->pmksa; 271 pmksa->pmksa = NULL; 272 while (entry) { 273 prev = entry; 274 entry = entry->next; 275 os_free(prev); 276 } 277 pmksa_cache_set_expiration(pmksa); 278 os_free(pmksa); 279 } 280 281 282 /** 283 * pmksa_cache_get - Fetch a PMKSA cache entry 284 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() 285 * @aa: Authenticator address or %NULL to match any 286 * @pmkid: PMKID or %NULL to match any 287 * Returns: Pointer to PMKSA cache entry or %NULL if no match was found 288 */ 289 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa, 290 const u8 *aa, const u8 *pmkid) 291 { 292 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; 293 while (entry) { 294 if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) && 295 (pmkid == NULL || 296 os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0)) 297 return entry; 298 entry = entry->next; 299 } 300 return NULL; 301 } 302 303 304 /** 305 * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache 306 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() 307 * 308 * Clear references to old data structures when wpa_supplicant is reconfigured. 309 */ 310 void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa) 311 { 312 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; 313 while (entry) { 314 entry->ssid = NULL; 315 entry = entry->next; 316 } 317 } 318 319 320 static struct rsn_pmksa_cache_entry * 321 pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa, 322 const struct rsn_pmksa_cache_entry *old_entry, 323 const u8 *aa) 324 { 325 struct rsn_pmksa_cache_entry *new_entry; 326 327 new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len, 328 aa, pmksa->sm->own_addr, old_entry->ssid); 329 if (new_entry == NULL) 330 return NULL; 331 332 /* TODO: reorder entries based on expiration time? */ 333 new_entry->expiration = old_entry->expiration; 334 new_entry->opportunistic = 1; 335 336 return new_entry; 337 } 338 339 340 /** 341 * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry 342 * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() 343 * @ssid: Pointer to the current network configuration 344 * @aa: Authenticator address for the new AP 345 * Returns: Pointer to a new PMKSA cache entry or %NULL if not available 346 * 347 * Try to create a new PMKSA cache entry opportunistically by guessing that the 348 * new AP is sharing the same PMK as another AP that has the same SSID and has 349 * already an entry in PMKSA cache. 350 */ 351 struct rsn_pmksa_cache_entry * 352 pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, 353 struct wpa_ssid *ssid, const u8 *aa) 354 { 355 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; 356 357 if (ssid == NULL) 358 return NULL; 359 while (entry) { 360 if (entry->ssid == ssid) { 361 entry = pmksa_cache_clone_entry(pmksa, entry, aa); 362 if (entry) { 363 wpa_printf(MSG_DEBUG, "RSN: added " 364 "opportunistic PMKSA cache entry " 365 "for " MACSTR, MAC2STR(aa)); 366 } 367 return entry; 368 } 369 entry = entry->next; 370 } 371 return NULL; 372 } 373 374 375 /** 376 * pmksa_cache_get_current - Get the current used PMKSA entry 377 * @sm: Pointer to WPA state machine data from wpa_sm_init() 378 * Returns: Pointer to the current PMKSA cache entry or %NULL if not available 379 */ 380 struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm) 381 { 382 if (sm == NULL) 383 return NULL; 384 return sm->cur_pmksa; 385 } 386 387 388 /** 389 * pmksa_cache_clear_current - Clear the current PMKSA entry selection 390 * @sm: Pointer to WPA state machine data from wpa_sm_init() 391 */ 392 void pmksa_cache_clear_current(struct wpa_sm *sm) 393 { 394 if (sm == NULL) 395 return; 396 sm->cur_pmksa = NULL; 397 } 398 399 400 /** 401 * pmksa_cache_set_current - Set the current PMKSA entry selection 402 * @sm: Pointer to WPA state machine data from wpa_sm_init() 403 * @pmkid: PMKID for selecting PMKSA or %NULL if not used 404 * @bssid: BSSID for PMKSA or %NULL if not used 405 * @ssid: The network configuration for the current network 406 * @try_opportunistic: Whether to allow opportunistic PMKSA caching 407 * Returns: 0 if PMKSA was found or -1 if no matching entry was found 408 */ 409 int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid, 410 const u8 *bssid, struct wpa_ssid *ssid, 411 int try_opportunistic) 412 { 413 struct rsn_pmksa_cache *pmksa = sm->pmksa; 414 sm->cur_pmksa = NULL; 415 if (pmkid) 416 sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid); 417 if (sm->cur_pmksa == NULL && bssid) 418 sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL); 419 if (sm->cur_pmksa == NULL && try_opportunistic && bssid) 420 sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa, ssid, 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 */ 503
