/* * WPA Supplicant - RSN PMKSA cache * Copyright (c) 2004-2006, Jouni Malinen * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * Alternatively, this software may be distributed under the terms of BSD * license. * * See README and COPYING for more details. */ #include "includes.h" #include "common.h" #include "wpa.h" #include "eloop.h" #include "config_ssid.h" #include "sha1.h" #include "wpa_i.h" #include "l2_packet.h" #include "eapol_sm.h" #include "pmksa_cache.h" #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2) static const int pmksa_cache_max_entries = 32; struct rsn_pmksa_cache { struct rsn_pmksa_cache_entry *pmksa; /* PMKSA cache */ int pmksa_count; /* number of entries in PMKSA cache */ struct wpa_sm *sm; /* TODO: get rid of this reference(?) */ void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx, int replace); void *ctx; }; /** * rsn_pmkid - Calculate PMK identifier * @pmk: Pairwise master key * @pmk_len: Length of pmk in bytes * @aa: Authenticator address * @spa: Supplicant address * * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA) */ static void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa, u8 *pmkid) { char *title = "PMK Name"; const u8 *addr[3]; const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN }; unsigned char hash[SHA1_MAC_LEN]; addr[0] = (u8 *) title; addr[1] = aa; addr[2] = spa; hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash); os_memcpy(pmkid, hash, PMKID_LEN); } static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa); static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry) { os_free(entry); } static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa, struct rsn_pmksa_cache_entry *entry, int replace) { pmksa->pmksa_count--; pmksa->free_cb(entry, pmksa->ctx, replace); _pmksa_cache_free_entry(entry); } static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx) { struct rsn_pmksa_cache *pmksa = eloop_ctx; struct os_time now; os_get_time(&now); while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) { struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; pmksa->pmksa = entry->next; wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for " MACSTR, MAC2STR(entry->aa)); pmksa_cache_free_entry(pmksa, entry, 0); } pmksa_cache_set_expiration(pmksa); } static void pmksa_cache_reauth(void *eloop_ctx, void *timeout_ctx) { struct rsn_pmksa_cache *pmksa = eloop_ctx; pmksa->sm->cur_pmksa = NULL; eapol_sm_request_reauth(pmksa->sm->eapol); } static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa) { int sec; struct rsn_pmksa_cache_entry *entry; struct os_time now; eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL); eloop_cancel_timeout(pmksa_cache_reauth, pmksa, NULL); if (pmksa->pmksa == NULL) return; os_get_time(&now); sec = pmksa->pmksa->expiration - now.sec; if (sec < 0) sec = 0; eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL); entry = pmksa->sm->cur_pmksa ? pmksa->sm->cur_pmksa : pmksa_cache_get(pmksa, pmksa->sm->bssid, NULL); if (entry) { sec = pmksa->pmksa->reauth_time - now.sec; if (sec < 0) sec = 0; eloop_register_timeout(sec, 0, pmksa_cache_reauth, pmksa, NULL); } } /** * pmksa_cache_add - Add a PMKSA cache entry * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() * @pmk: The new pairwise master key * @pmk_len: PMK length in bytes, usually PMK_LEN (32) * @aa: Authenticator address * @spa: Supplicant address * @ssid: The network configuration for which this PMK is being added * Returns: Pointer to the added PMKSA cache entry or %NULL on error * * This function create a PMKSA entry for a new PMK and adds it to the PMKSA * cache. If an old entry is already in the cache for the same Authenticator, * this entry will be replaced with the new entry. PMKID will be calculated * based on the PMK and the driver interface is notified of the new PMKID. */ struct rsn_pmksa_cache_entry * pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa, struct wpa_ssid *ssid) { struct rsn_pmksa_cache_entry *entry, *pos, *prev; struct os_time now; if (pmksa->sm->proto != WPA_PROTO_RSN || pmk_len > PMK_LEN) return NULL; entry = os_zalloc(sizeof(*entry)); if (entry == NULL) return NULL; os_memcpy(entry->pmk, pmk, pmk_len); entry->pmk_len = pmk_len; rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid); os_get_time(&now); entry->expiration = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime; entry->reauth_time = now.sec + pmksa->sm->dot11RSNAConfigPMKLifetime * pmksa->sm->dot11RSNAConfigPMKReauthThreshold / 100; entry->akmp = WPA_KEY_MGMT_IEEE8021X; os_memcpy(entry->aa, aa, ETH_ALEN); entry->ssid = ssid; /* Replace an old entry for the same Authenticator (if found) with the * new entry */ pos = pmksa->pmksa; prev = NULL; while (pos) { if (os_memcmp(aa, pos->aa, ETH_ALEN) == 0) { if (pos->pmk_len == pmk_len && os_memcmp(pos->pmk, pmk, pmk_len) == 0 && os_memcmp(pos->pmkid, entry->pmkid, PMKID_LEN) == 0) { wpa_printf(MSG_DEBUG, "WPA: reusing previous " "PMKSA entry"); os_free(entry); return pos; } if (prev == NULL) pmksa->pmksa = pos->next; else prev->next = pos->next; if (pos == pmksa->sm->cur_pmksa) { /* We are about to replace the current PMKSA * cache entry. This happens when the PMKSA * caching attempt fails, so we don't want to * force pmksa_cache_free_entry() to disconnect * at this point. Let's just make sure the old * PMKSA cache entry will not be used in the * future. */ wpa_printf(MSG_DEBUG, "RSN: replacing current " "PMKSA entry"); pmksa->sm->cur_pmksa = NULL; } wpa_printf(MSG_DEBUG, "RSN: Replace PMKSA entry for " "the current AP"); pmksa_cache_free_entry(pmksa, pos, 1); break; } prev = pos; pos = pos->next; } if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) { /* Remove the oldest entry to make room for the new entry */ pos = pmksa->pmksa; pmksa->pmksa = pos->next; wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache " "entry (for " MACSTR ") to make room for new one", MAC2STR(pos->aa)); wpa_sm_remove_pmkid(pmksa->sm, pos->aa, pos->pmkid); pmksa_cache_free_entry(pmksa, pos, 0); } /* Add the new entry; order by expiration time */ pos = pmksa->pmksa; prev = NULL; while (pos) { if (pos->expiration > entry->expiration) break; prev = pos; pos = pos->next; } if (prev == NULL) { entry->next = pmksa->pmksa; pmksa->pmksa = entry; pmksa_cache_set_expiration(pmksa); } else { entry->next = prev->next; prev->next = entry; } pmksa->pmksa_count++; wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR, MAC2STR(entry->aa)); wpa_sm_add_pmkid(pmksa->sm, entry->aa, entry->pmkid); return entry; } /** * pmksa_cache_deinit - Free all entries in PMKSA cache * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() */ void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa) { struct rsn_pmksa_cache_entry *entry, *prev; if (pmksa == NULL) return; entry = pmksa->pmksa; pmksa->pmksa = NULL; while (entry) { prev = entry; entry = entry->next; os_free(prev); } pmksa_cache_set_expiration(pmksa); os_free(pmksa); } /** * pmksa_cache_get - Fetch a PMKSA cache entry * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() * @aa: Authenticator address or %NULL to match any * @pmkid: PMKID or %NULL to match any * Returns: Pointer to PMKSA cache entry or %NULL if no match was found */ struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa, const u8 *aa, const u8 *pmkid) { struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; while (entry) { if ((aa == NULL || os_memcmp(entry->aa, aa, ETH_ALEN) == 0) && (pmkid == NULL || os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0)) return entry; entry = entry->next; } return NULL; } /** * pmksa_cache_notify_reconfig - Reconfiguration notification for PMKSA cache * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() * * Clear references to old data structures when wpa_supplicant is reconfigured. */ void pmksa_cache_notify_reconfig(struct rsn_pmksa_cache *pmksa) { struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; while (entry) { entry->ssid = NULL; entry = entry->next; } } static struct rsn_pmksa_cache_entry * pmksa_cache_clone_entry(struct rsn_pmksa_cache *pmksa, const struct rsn_pmksa_cache_entry *old_entry, const u8 *aa) { struct rsn_pmksa_cache_entry *new_entry; new_entry = pmksa_cache_add(pmksa, old_entry->pmk, old_entry->pmk_len, aa, pmksa->sm->own_addr, old_entry->ssid); if (new_entry == NULL) return NULL; /* TODO: reorder entries based on expiration time? */ new_entry->expiration = old_entry->expiration; new_entry->opportunistic = 1; return new_entry; } /** * pmksa_cache_get_opportunistic - Try to get an opportunistic PMKSA entry * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init() * @ssid: Pointer to the current network configuration * @aa: Authenticator address for the new AP * Returns: Pointer to a new PMKSA cache entry or %NULL if not available * * Try to create a new PMKSA cache entry opportunistically by guessing that the * new AP is sharing the same PMK as another AP that has the same SSID and has * already an entry in PMKSA cache. */ struct rsn_pmksa_cache_entry * pmksa_cache_get_opportunistic(struct rsn_pmksa_cache *pmksa, struct wpa_ssid *ssid, const u8 *aa) { struct rsn_pmksa_cache_entry *entry = pmksa->pmksa; if (ssid == NULL) return NULL; while (entry) { if (entry->ssid == ssid) { entry = pmksa_cache_clone_entry(pmksa, entry, aa); if (entry) { wpa_printf(MSG_DEBUG, "RSN: added " "opportunistic PMKSA cache entry " "for " MACSTR, MAC2STR(aa)); } return entry; } entry = entry->next; } return NULL; } /** * pmksa_cache_get_current - Get the current used PMKSA entry * @sm: Pointer to WPA state machine data from wpa_sm_init() * Returns: Pointer to the current PMKSA cache entry or %NULL if not available */ struct rsn_pmksa_cache_entry * pmksa_cache_get_current(struct wpa_sm *sm) { if (sm == NULL) return NULL; return sm->cur_pmksa; } /** * pmksa_cache_clear_current - Clear the current PMKSA entry selection * @sm: Pointer to WPA state machine data from wpa_sm_init() */ void pmksa_cache_clear_current(struct wpa_sm *sm) { if (sm == NULL) return; sm->cur_pmksa = NULL; } /** * pmksa_cache_set_current - Set the current PMKSA entry selection * @sm: Pointer to WPA state machine data from wpa_sm_init() * @pmkid: PMKID for selecting PMKSA or %NULL if not used * @bssid: BSSID for PMKSA or %NULL if not used * @ssid: The network configuration for the current network * @try_opportunistic: Whether to allow opportunistic PMKSA caching * Returns: 0 if PMKSA was found or -1 if no matching entry was found */ int pmksa_cache_set_current(struct wpa_sm *sm, const u8 *pmkid, const u8 *bssid, struct wpa_ssid *ssid, int try_opportunistic) { struct rsn_pmksa_cache *pmksa = sm->pmksa; sm->cur_pmksa = NULL; if (pmkid) sm->cur_pmksa = pmksa_cache_get(pmksa, NULL, pmkid); if (sm->cur_pmksa == NULL && bssid) sm->cur_pmksa = pmksa_cache_get(pmksa, bssid, NULL); if (sm->cur_pmksa == NULL && try_opportunistic && bssid) sm->cur_pmksa = pmksa_cache_get_opportunistic(pmksa, ssid, bssid); if (sm->cur_pmksa) { wpa_hexdump(MSG_DEBUG, "RSN: PMKID", sm->cur_pmksa->pmkid, PMKID_LEN); return 0; } return -1; } /** * pmksa_cache_list - Dump text list of entries in PMKSA cache * @sm: Pointer to WPA state machine data from wpa_sm_init() * @buf: Buffer for the list * @len: Length of the buffer * Returns: number of bytes written to buffer * * This function is used to generate a text format representation of the * current PMKSA cache contents for the ctrl_iface PMKSA command. */ int pmksa_cache_list(struct wpa_sm *sm, char *buf, size_t len) { int i, ret; char *pos = buf; struct rsn_pmksa_cache_entry *entry; struct os_time now; os_get_time(&now); ret = os_snprintf(pos, buf + len - pos, "Index / AA / PMKID / expiration (in seconds) / " "opportunistic\n"); if (ret < 0 || ret >= buf + len - pos) return pos - buf; pos += ret; i = 0; entry = sm->pmksa->pmksa; while (entry) { i++; ret = os_snprintf(pos, buf + len - pos, "%d " MACSTR " ", i, MAC2STR(entry->aa)); if (ret < 0 || ret >= buf + len - pos) return pos - buf; pos += ret; pos += wpa_snprintf_hex(pos, buf + len - pos, entry->pmkid, PMKID_LEN); ret = os_snprintf(pos, buf + len - pos, " %d %d\n", (int) (entry->expiration - now.sec), entry->opportunistic); if (ret < 0 || ret >= buf + len - pos) return pos - buf; pos += ret; entry = entry->next; } return pos - buf; } /** * pmksa_cache_init - Initialize PMKSA cache * @free_cb: Callback function to be called when a PMKSA cache entry is freed * @ctx: Context pointer for free_cb function * @sm: Pointer to WPA state machine data from wpa_sm_init() * Returns: Pointer to PMKSA cache data or %NULL on failure */ struct rsn_pmksa_cache * pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx, int replace), void *ctx, struct wpa_sm *sm) { struct rsn_pmksa_cache *pmksa; pmksa = os_zalloc(sizeof(*pmksa)); if (pmksa) { pmksa->free_cb = free_cb; pmksa->ctx = ctx; pmksa->sm = sm; } return pmksa; } #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */