krackattacks/src/ap/ieee802_11_auth.c

/*
 * hostapd / IEEE 802.11 authentication (ACL)
 * Copyright (c) 2003-2012, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 *
 * Access control list for IEEE 802.11 authentication can uses statically
 * configured ACL from configuration files or an external RADIUS server.
 * Results from external RADIUS queries are cached to allow faster
 * authentication frame processing.
 */

#include "utils/includes.h"

#include "utils/common.h"
#include "utils/eloop.h"
#include "radius/radius.h"
#include "radius/radius_client.h"
#include "hostapd.h"
#include "ap_config.h"
#include "ap_drv_ops.h"
#include "ieee802_11.h"
#include "ieee802_1x.h"
#include "ieee802_11_auth.h"

#define RADIUS_ACL_TIMEOUT 30


struct hostapd_cached_radius_acl {
	struct os_reltime timestamp;
	macaddr addr;
	int accepted; /* HOSTAPD_ACL_* */
	struct hostapd_cached_radius_acl *next;
	u32 session_timeout;
	u32 acct_interim_interval;
	struct vlan_description vlan_id;
	struct hostapd_sta_wpa_psk_short *psk;
	char *identity;
	char *radius_cui;
};


struct hostapd_acl_query_data {
	struct os_reltime timestamp;
	u8 radius_id;
	macaddr addr;
	u8 *auth_msg; /* IEEE 802.11 authentication frame from station */
	size_t auth_msg_len;
	struct hostapd_acl_query_data *next;
};


#ifndef CONFIG_NO_RADIUS
static void hostapd_acl_cache_free_entry(struct hostapd_cached_radius_acl *e)
{
	os_free(e->identity);
	os_free(e->radius_cui);
	hostapd_free_psk_list(e->psk);
	os_free(e);
}


static void hostapd_acl_cache_free(struct hostapd_cached_radius_acl *acl_cache)
{
	struct hostapd_cached_radius_acl *prev;

	while (acl_cache) {
		prev = acl_cache;
		acl_cache = acl_cache->next;
		hostapd_acl_cache_free_entry(prev);
	}
}


static void copy_psk_list(struct hostapd_sta_wpa_psk_short **psk,
			  struct hostapd_sta_wpa_psk_short *src)
{
	if (!psk)
		return;

	if (src)
		src->ref++;

	*psk = src;
}


static int hostapd_acl_cache_get(struct hostapd_data *hapd, const u8 *addr,
				 u32 *session_timeout,
				 u32 *acct_interim_interval,
				 struct vlan_description *vlan_id,
				 struct hostapd_sta_wpa_psk_short **psk,
				 char **identity, char **radius_cui)
{
	struct hostapd_cached_radius_acl *entry;
	struct os_reltime now;

	os_get_reltime(&now);

	for (entry = hapd->acl_cache; entry; entry = entry->next) {
		if (os_memcmp(entry->addr, addr, ETH_ALEN) != 0)
			continue;

		if (os_reltime_expired(&now, &entry->timestamp,
				       RADIUS_ACL_TIMEOUT))
			return -1; /* entry has expired */
		if (entry->accepted == HOSTAPD_ACL_ACCEPT_TIMEOUT)
			if (session_timeout)
				*session_timeout = entry->session_timeout;
		if (acct_interim_interval)
			*acct_interim_interval =
				entry->acct_interim_interval;
		if (vlan_id)
			*vlan_id = entry->vlan_id;
		copy_psk_list(psk, entry->psk);
		if (identity) {
			if (entry->identity)
				*identity = os_strdup(entry->identity);
			else
				*identity = NULL;
		}
		if (radius_cui) {
			if (entry->radius_cui)
				*radius_cui = os_strdup(entry->radius_cui);
			else
				*radius_cui = NULL;
		}
		return entry->accepted;
	}

	return -1;
}
#endif /* CONFIG_NO_RADIUS */


static void hostapd_acl_query_free(struct hostapd_acl_query_data *query)
{
	if (query == NULL)
		return;
	os_free(query->auth_msg);
	os_free(query);
}


#ifndef CONFIG_NO_RADIUS
static int hostapd_radius_acl_query(struct hostapd_data *hapd, const u8 *addr,
				    struct hostapd_acl_query_data *query)
{
	struct radius_msg *msg;
	char buf[128];

	query->radius_id = radius_client_get_id(hapd->radius);
	msg = radius_msg_new(RADIUS_CODE_ACCESS_REQUEST, query->radius_id);
	if (msg == NULL)
		return -1;

	if (radius_msg_make_authenticator(msg) < 0) {
		wpa_printf(MSG_INFO, "Could not make Request Authenticator");
		goto fail;
	}

	os_snprintf(buf, sizeof(buf), RADIUS_ADDR_FORMAT, MAC2STR(addr));
	if (!radius_msg_add_attr(msg, RADIUS_ATTR_USER_NAME, (u8 *) buf,
				 os_strlen(buf))) {
		wpa_printf(MSG_DEBUG, "Could not add User-Name");
		goto fail;
	}

	if (!radius_msg_add_attr_user_password(
		    msg, (u8 *) buf, os_strlen(buf),
		    hapd->conf->radius->auth_server->shared_secret,
		    hapd->conf->radius->auth_server->shared_secret_len)) {
		wpa_printf(MSG_DEBUG, "Could not add User-Password");
		goto fail;
	}

	if (add_common_radius_attr(hapd, hapd->conf->radius_auth_req_attr,
				   NULL, msg) < 0)
		goto fail;

	os_snprintf(buf, sizeof(buf), RADIUS_802_1X_ADDR_FORMAT,
		    MAC2STR(addr));
	if (!radius_msg_add_attr(msg, RADIUS_ATTR_CALLING_STATION_ID,
				 (u8 *) buf, os_strlen(buf))) {
		wpa_printf(MSG_DEBUG, "Could not add Calling-Station-Id");
		goto fail;
	}

	os_snprintf(buf, sizeof(buf), "CONNECT 11Mbps 802.11b");
	if (!radius_msg_add_attr(msg, RADIUS_ATTR_CONNECT_INFO,
				 (u8 *) buf, os_strlen(buf))) {
		wpa_printf(MSG_DEBUG, "Could not add Connect-Info");
		goto fail;
	}

	if (radius_client_send(hapd->radius, msg, RADIUS_AUTH, addr) < 0)
		goto fail;
	return 0;

 fail:
	radius_msg_free(msg);
	return -1;
}
#endif /* CONFIG_NO_RADIUS */


/**
 * hostapd_check_acl - Check a specified STA against accept/deny ACLs
 * @hapd: hostapd BSS data
 * @addr: MAC address of the STA
 * @vlan_id: Buffer for returning VLAN ID
 * Returns: HOSTAPD_ACL_ACCEPT, HOSTAPD_ACL_REJECT, or HOSTAPD_ACL_PENDING
 */
int hostapd_check_acl(struct hostapd_data *hapd, const u8 *addr,
		      struct vlan_description *vlan_id)
{
	if (hostapd_maclist_found(hapd->conf->accept_mac,
				  hapd->conf->num_accept_mac, addr, vlan_id))
		return HOSTAPD_ACL_ACCEPT;

	if (hostapd_maclist_found(hapd->conf->deny_mac,
				  hapd->conf->num_deny_mac, addr, vlan_id))
		return HOSTAPD_ACL_REJECT;

	if (hapd->conf->macaddr_acl == ACCEPT_UNLESS_DENIED)
		return HOSTAPD_ACL_ACCEPT;
	if (hapd->conf->macaddr_acl == DENY_UNLESS_ACCEPTED)
		return HOSTAPD_ACL_REJECT;

	return HOSTAPD_ACL_PENDING;
}


/**
 * hostapd_allowed_address - Check whether a specified STA can be authenticated
 * @hapd: hostapd BSS data
 * @addr: MAC address of the STA
 * @msg: Authentication message
 * @len: Length of msg in octets
 * @session_timeout: Buffer for returning session timeout (from RADIUS)
 * @acct_interim_interval: Buffer for returning account interval (from RADIUS)
 * @vlan_id: Buffer for returning VLAN ID
 * @psk: Linked list buffer for returning WPA PSK
 * @identity: Buffer for returning identity (from RADIUS)
 * @radius_cui: Buffer for returning CUI (from RADIUS)
 * @is_probe_req: Whether this query for a Probe Request frame
 * Returns: HOSTAPD_ACL_ACCEPT, HOSTAPD_ACL_REJECT, or HOSTAPD_ACL_PENDING
 *
 * The caller is responsible for freeing the returned *identity and *radius_cui
 * values with os_free().
 */
int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
			    const u8 *msg, size_t len, u32 *session_timeout,
			    u32 *acct_interim_interval,
			    struct vlan_description *vlan_id,
			    struct hostapd_sta_wpa_psk_short **psk,
			    char **identity, char **radius_cui,
			    int is_probe_req)
{
	int res;

	if (session_timeout)
		*session_timeout = 0;
	if (acct_interim_interval)
		*acct_interim_interval = 0;
	if (vlan_id)
		os_memset(vlan_id, 0, sizeof(*vlan_id));
	if (psk)
		*psk = NULL;
	if (identity)
		*identity = NULL;
	if (radius_cui)
		*radius_cui = NULL;

	res = hostapd_check_acl(hapd, addr, vlan_id);
	if (res != HOSTAPD_ACL_PENDING)
		return res;

	if (hapd->conf->macaddr_acl == USE_EXTERNAL_RADIUS_AUTH) {
#ifdef CONFIG_NO_RADIUS
		return HOSTAPD_ACL_REJECT;
#else /* CONFIG_NO_RADIUS */
		struct hostapd_acl_query_data *query;

		if (is_probe_req) {
			/* Skip RADIUS queries for Probe Request frames to avoid
			 * excessive load on the authentication server. */
			return HOSTAPD_ACL_ACCEPT;
		};

		/* Check whether ACL cache has an entry for this station */
		res = hostapd_acl_cache_get(hapd, addr, session_timeout,
					    acct_interim_interval, vlan_id, psk,
					    identity, radius_cui);
		if (res == HOSTAPD_ACL_ACCEPT ||
		    res == HOSTAPD_ACL_ACCEPT_TIMEOUT)
			return res;
		if (res == HOSTAPD_ACL_REJECT)
			return HOSTAPD_ACL_REJECT;

		query = hapd->acl_queries;
		while (query) {
			if (os_memcmp(query->addr, addr, ETH_ALEN) == 0) {
				/* pending query in RADIUS retransmit queue;
				 * do not generate a new one */
				if (identity) {
					os_free(*identity);
					*identity = NULL;
				}
				if (radius_cui) {
					os_free(*radius_cui);
					*radius_cui = NULL;
				}
				return HOSTAPD_ACL_PENDING;
			}
			query = query->next;
		}

		if (!hapd->conf->radius->auth_server)
			return HOSTAPD_ACL_REJECT;

		/* No entry in the cache - query external RADIUS server */
		query = os_zalloc(sizeof(*query));
		if (query == NULL) {
			wpa_printf(MSG_ERROR, "malloc for query data failed");
			return HOSTAPD_ACL_REJECT;
		}
		os_get_reltime(&query->timestamp);
		os_memcpy(query->addr, addr, ETH_ALEN);
		if (hostapd_radius_acl_query(hapd, addr, query)) {
			wpa_printf(MSG_DEBUG, "Failed to send Access-Request "
				   "for ACL query.");
			hostapd_acl_query_free(query);
			return HOSTAPD_ACL_REJECT;
		}

		query->auth_msg = os_memdup(msg, len);
		if (query->auth_msg == NULL) {
			wpa_printf(MSG_ERROR, "Failed to allocate memory for "
				   "auth frame.");
			hostapd_acl_query_free(query);
			return HOSTAPD_ACL_REJECT;
		}
		query->auth_msg_len = len;
		query->next = hapd->acl_queries;
		hapd->acl_queries = query;

		/* Queued data will be processed in hostapd_acl_recv_radius()
		 * when RADIUS server replies to the sent Access-Request. */
		return HOSTAPD_ACL_PENDING;
#endif /* CONFIG_NO_RADIUS */
	}

	return HOSTAPD_ACL_REJECT;
}


#ifndef CONFIG_NO_RADIUS
static void hostapd_acl_expire_cache(struct hostapd_data *hapd,
				     struct os_reltime *now)
{
	struct hostapd_cached_radius_acl *prev, *entry, *tmp;

	prev = NULL;
	entry = hapd->acl_cache;

	while (entry) {
		if (os_reltime_expired(now, &entry->timestamp,
				       RADIUS_ACL_TIMEOUT)) {
			wpa_printf(MSG_DEBUG, "Cached ACL entry for " MACSTR
				   " has expired.", MAC2STR(entry->addr));
			if (prev)
				prev->next = entry->next;
			else
				hapd->acl_cache = entry->next;
			hostapd_drv_set_radius_acl_expire(hapd, entry->addr);
			tmp = entry;
			entry = entry->next;
			hostapd_acl_cache_free_entry(tmp);
			continue;
		}

		prev = entry;
		entry = entry->next;
	}
}


static void hostapd_acl_expire_queries(struct hostapd_data *hapd,
				       struct os_reltime *now)
{
	struct hostapd_acl_query_data *prev, *entry, *tmp;

	prev = NULL;
	entry = hapd->acl_queries;

	while (entry) {
		if (os_reltime_expired(now, &entry->timestamp,
				       RADIUS_ACL_TIMEOUT)) {
			wpa_printf(MSG_DEBUG, "ACL query for " MACSTR
				   " has expired.", MAC2STR(entry->addr));
			if (prev)
				prev->next = entry->next;
			else
				hapd->acl_queries = entry->next;

			tmp = entry;
			entry = entry->next;
			hostapd_acl_query_free(tmp);
			continue;
		}

		prev = entry;
		entry = entry->next;
	}
}


/**
 * hostapd_acl_expire - ACL cache expiration callback
 * @hapd: struct hostapd_data *
 */
void hostapd_acl_expire(struct hostapd_data *hapd)
{
	struct os_reltime now;

	os_get_reltime(&now);
	hostapd_acl_expire_cache(hapd, &now);
	hostapd_acl_expire_queries(hapd, &now);
}


static void decode_tunnel_passwords(struct hostapd_data *hapd,
				    const u8 *shared_secret,
				    size_t shared_secret_len,
				    struct radius_msg *msg,
				    struct radius_msg *req,
				    struct hostapd_cached_radius_acl *cache)
{
	int passphraselen;
	char *passphrase;
	size_t i;
	struct hostapd_sta_wpa_psk_short *psk;

	/*
	 * Decode all tunnel passwords as PSK and save them into a linked list.
	 */
	for (i = 0; ; i++) {
		passphrase = radius_msg_get_tunnel_password(
			msg, &passphraselen, shared_secret, shared_secret_len,
			req, i);
		/*
		 * Passphrase is NULL iff there is no i-th Tunnel-Password
		 * attribute in msg.
		 */
		if (passphrase == NULL)
			break;

		/*
		 * Passphase should be 8..63 chars (to be hashed with SSID)
		 * or 64 chars hex string (no separate hashing with SSID).
		 */

		if (passphraselen < MIN_PASSPHRASE_LEN ||
		    passphraselen > MAX_PASSPHRASE_LEN + 1)
			goto free_pass;

		/*
		 * passphrase does not contain the NULL termination.
		 * Add it here as pbkdf2_sha1() requires it.
		 */
		psk = os_zalloc(sizeof(struct hostapd_sta_wpa_psk_short));
		if (psk) {
			if ((passphraselen == MAX_PASSPHRASE_LEN + 1) &&
			    (hexstr2bin(passphrase, psk->psk, PMK_LEN) < 0)) {
				hostapd_logger(hapd, cache->addr,
					       HOSTAPD_MODULE_RADIUS,
					       HOSTAPD_LEVEL_WARNING,
					       "invalid hex string (%d chars) in Tunnel-Password",
					       passphraselen);
				goto skip;
			} else if (passphraselen <= MAX_PASSPHRASE_LEN) {
				os_memcpy(psk->passphrase, passphrase,
					  passphraselen);
				psk->is_passphrase = 1;
			}
			psk->next = cache->psk;
			cache->psk = psk;
			psk = NULL;
		}
skip:
		os_free(psk);
free_pass:
		os_free(passphrase);
	}
}


/**
 * hostapd_acl_recv_radius - Process incoming RADIUS Authentication messages
 * @msg: RADIUS response message
 * @req: RADIUS request message
 * @shared_secret: RADIUS shared secret
 * @shared_secret_len: Length of shared_secret in octets
 * @data: Context data (struct hostapd_data *)
 * Returns: RADIUS_RX_PROCESSED if RADIUS message was a reply to ACL query (and
 * was processed here) or RADIUS_RX_UNKNOWN if not.
 */
static RadiusRxResult
hostapd_acl_recv_radius(struct radius_msg *msg, struct radius_msg *req,
			const u8 *shared_secret, size_t shared_secret_len,
			void *data)
{
	struct hostapd_data *hapd = data;
	struct hostapd_acl_query_data *query, *prev;
	struct hostapd_cached_radius_acl *cache;
	struct radius_hdr *hdr = radius_msg_get_hdr(msg);
	int *untagged, *tagged, *notempty;

	query = hapd->acl_queries;
	prev = NULL;
	while (query) {
		if (query->radius_id == hdr->identifier)
			break;
		prev = query;
		query = query->next;
	}
	if (query == NULL)
		return RADIUS_RX_UNKNOWN;

	wpa_printf(MSG_DEBUG, "Found matching Access-Request for RADIUS "
		   "message (id=%d)", query->radius_id);

	if (radius_msg_verify(msg, shared_secret, shared_secret_len, req, 0)) {
		wpa_printf(MSG_INFO, "Incoming RADIUS packet did not have "
			   "correct authenticator - dropped\n");
		return RADIUS_RX_INVALID_AUTHENTICATOR;
	}

	if (hdr->code != RADIUS_CODE_ACCESS_ACCEPT &&
	    hdr->code != RADIUS_CODE_ACCESS_REJECT) {
		wpa_printf(MSG_DEBUG, "Unknown RADIUS message code %d to ACL "
			   "query", hdr->code);
		return RADIUS_RX_UNKNOWN;
	}

	/* Insert Accept/Reject info into ACL cache */
	cache = os_zalloc(sizeof(*cache));
	if (cache == NULL) {
		wpa_printf(MSG_DEBUG, "Failed to add ACL cache entry");
		goto done;
	}
	os_get_reltime(&cache->timestamp);
	os_memcpy(cache->addr, query->addr, sizeof(cache->addr));
	if (hdr->code == RADIUS_CODE_ACCESS_ACCEPT) {
		u8 *buf;
		size_t len;

		if (radius_msg_get_attr_int32(msg, RADIUS_ATTR_SESSION_TIMEOUT,
					      &cache->session_timeout) == 0)
			cache->accepted = HOSTAPD_ACL_ACCEPT_TIMEOUT;
		else
			cache->accepted = HOSTAPD_ACL_ACCEPT;

		if (radius_msg_get_attr_int32(
			    msg, RADIUS_ATTR_ACCT_INTERIM_INTERVAL,
			    &cache->acct_interim_interval) == 0 &&
		    cache->acct_interim_interval < 60) {
			wpa_printf(MSG_DEBUG, "Ignored too small "
				   "Acct-Interim-Interval %d for STA " MACSTR,
				   cache->acct_interim_interval,
				   MAC2STR(query->addr));
			cache->acct_interim_interval = 0;
		}

		notempty = &cache->vlan_id.notempty;
		untagged = &cache->vlan_id.untagged;
		tagged = cache->vlan_id.tagged;
		*notempty = !!radius_msg_get_vlanid(msg, untagged,
						    MAX_NUM_TAGGED_VLAN,
						    tagged);

		decode_tunnel_passwords(hapd, shared_secret, shared_secret_len,
					msg, req, cache);

		if (radius_msg_get_attr_ptr(msg, RADIUS_ATTR_USER_NAME,
					    &buf, &len, NULL) == 0) {
			cache->identity = os_zalloc(len + 1);
			if (cache->identity)
				os_memcpy(cache->identity, buf, len);
		}
		if (radius_msg_get_attr_ptr(
			    msg, RADIUS_ATTR_CHARGEABLE_USER_IDENTITY,
			    &buf, &len, NULL) == 0) {
			cache->radius_cui = os_zalloc(len + 1);
			if (cache->radius_cui)
				os_memcpy(cache->radius_cui, buf, len);
		}

		if (hapd->conf->wpa_psk_radius == PSK_RADIUS_REQUIRED &&
		    !cache->psk)
			cache->accepted = HOSTAPD_ACL_REJECT;

		if (cache->vlan_id.notempty &&
		    !hostapd_vlan_valid(hapd->conf->vlan, &cache->vlan_id)) {
			hostapd_logger(hapd, query->addr,
				       HOSTAPD_MODULE_RADIUS,
				       HOSTAPD_LEVEL_INFO,
				       "Invalid VLAN %d%s received from RADIUS server",
				       cache->vlan_id.untagged,
				       cache->vlan_id.tagged[0] ? "+" : "");
			os_memset(&cache->vlan_id, 0, sizeof(cache->vlan_id));
		}
		if (hapd->conf->ssid.dynamic_vlan == DYNAMIC_VLAN_REQUIRED &&
		    !cache->vlan_id.notempty)
			cache->accepted = HOSTAPD_ACL_REJECT;
	} else
		cache->accepted = HOSTAPD_ACL_REJECT;
	cache->next = hapd->acl_cache;
	hapd->acl_cache = cache;

#ifdef CONFIG_DRIVER_RADIUS_ACL
	hostapd_drv_set_radius_acl_auth(hapd, query->addr, cache->accepted,
					cache->session_timeout);
#else /* CONFIG_DRIVER_RADIUS_ACL */
#ifdef NEED_AP_MLME
	/* Re-send original authentication frame for 802.11 processing */
	wpa_printf(MSG_DEBUG, "Re-sending authentication frame after "
		   "successful RADIUS ACL query");
	ieee802_11_mgmt(hapd, query->auth_msg, query->auth_msg_len, NULL);
#endif /* NEED_AP_MLME */
#endif /* CONFIG_DRIVER_RADIUS_ACL */

 done:
	if (prev == NULL)
		hapd->acl_queries = query->next;
	else
		prev->next = query->next;

	hostapd_acl_query_free(query);

	return RADIUS_RX_PROCESSED;
}
#endif /* CONFIG_NO_RADIUS */


/**
 * hostapd_acl_init: Initialize IEEE 802.11 ACL
 * @hapd: hostapd BSS data
 * Returns: 0 on success, -1 on failure
 */
int hostapd_acl_init(struct hostapd_data *hapd)
{
#ifndef CONFIG_NO_RADIUS
	if (radius_client_register(hapd->radius, RADIUS_AUTH,
				   hostapd_acl_recv_radius, hapd))
		return -1;
#endif /* CONFIG_NO_RADIUS */

	return 0;
}


/**
 * hostapd_acl_deinit - Deinitialize IEEE 802.11 ACL
 * @hapd: hostapd BSS data
 */
void hostapd_acl_deinit(struct hostapd_data *hapd)
{
	struct hostapd_acl_query_data *query, *prev;

#ifndef CONFIG_NO_RADIUS
	hostapd_acl_cache_free(hapd->acl_cache);
	hapd->acl_cache = NULL;
#endif /* CONFIG_NO_RADIUS */

	query = hapd->acl_queries;
	hapd->acl_queries = NULL;
	while (query) {
		prev = query;
		query = query->next;
		hostapd_acl_query_free(prev);
	}
}


void hostapd_free_psk_list(struct hostapd_sta_wpa_psk_short *psk)
{
	if (psk && psk->ref) {
		/* This will be freed when the last reference is dropped. */
		psk->ref--;
		return;
	}

	while (psk) {
		struct hostapd_sta_wpa_psk_short *prev = psk;
		psk = psk->next;
		os_free(prev);
	}
}