freebsd-dev/contrib/wpa_supplicant/pmksa_cache.c
2007-07-11 15:48:36 +00:00

503 lines
14 KiB
C

/*
* WPA Supplicant - RSN PMKSA cache
* Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
*
* 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 */