GAS: Add support to randomize transmitter address

Add support to send GAS requests with a randomized transmitter address
if supported by the driver. The following control interface commands
(and matching configuration file parameters) can be used to configure
different types of randomization:

"SET gas_rand_mac_addr 0" to disable randomizing TX MAC address,
"SET gas_rand_mac_addr 1" to randomize the complete TX MAC address,
"SET gas_rand_mac_addr 2" to randomize the TX MAC address except for OUI.

A new random MAC address will be generated for every
gas_rand_addr_lifetime seconds and this can be configured with
"SET gas_rand_addr_lifetime <timeout>".

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/config.c

@@ -3748,6 +3748,7 @@ struct wpa_config * wpa_config_alloc_empty(const char *ctrl_interface,
 		config->ctrl_interface = os_strdup(ctrl_interface);
 	if (driver_param)
 		config->driver_param = os_strdup(driver_param);
+	config->gas_rand_addr_lifetime = DEFAULT_RAND_ADDR_LIFETIME;
 
 	return config;
 }
@@ -4456,6 +4457,8 @@ static const struct global_parse_data global_fields[] = {
 	{ INT(gas_address3), 0 },
 	{ INT_RANGE(ftm_responder, 0, 1), 0 },
 	{ INT_RANGE(ftm_initiator, 0, 1), 0 },
+	{ INT(gas_rand_addr_lifetime), 0 },
+	{ INT_RANGE(gas_rand_mac_addr, 0, 2), 0 },
 };
 
 #undef FUNC

wpa_supplicant/config.h

@@ -1328,6 +1328,21 @@ struct wpa_config {
 	 * wpa_supplicant.
 	 */
 	int ftm_initiator;
+
+	/**
+	 * gas_rand_addr_lifetime - Lifetime of random MAC address for ANQP in
+	 *	seconds
+	 */
+	unsigned int gas_rand_addr_lifetime;
+
+	/**
+	 * gas_rand_mac_addr - GAS MAC address policy
+	 *
+	 * 0 = use permanent MAC address
+	 * 1 = use random MAC address
+	 * 2 = like 1, but maintain OUI (with local admin bit set)
+	 */
+	int gas_rand_mac_addr;
 };
 
 

wpa_supplicant/config_file.c

@@ -1413,6 +1413,13 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 		fprintf(f, "fst_priority=%d\n", config->fst_priority);
 	if (config->fst_llt)
 		fprintf(f, "fst_llt=%d\n", config->fst_llt);
+
+	if (config->gas_rand_addr_lifetime != DEFAULT_RAND_ADDR_LIFETIME)
+		fprintf(f, "gas_rand_addr_lifetime=%u\n",
+			config->gas_rand_addr_lifetime);
+	if (config->gas_rand_mac_addr)
+		fprintf(f, "gas_rand_mac_addr=%d\n", config->gas_rand_mac_addr);
+
 }
 
 #endif /* CONFIG_NO_CONFIG_WRITE */

wpa_supplicant/gas_query.c

@@ -53,6 +53,7 @@ struct gas_query_pending {
 		   const struct wpabuf *adv_proto,
 		   const struct wpabuf *resp, u16 status_code);
 	void *ctx;
+	u8 sa[ETH_ALEN];
 };
 
 /**
@@ -63,6 +64,9 @@ struct gas_query {
 	struct dl_list pending; /* struct gas_query_pending */
 	struct gas_query_pending *current;
 	struct wpa_radio_work *work;
+	struct os_reltime last_mac_addr_rand;
+	int last_rand_sa_type;
+	u8 rand_addr[ETH_ALEN];
 };
 
 
@@ -278,8 +282,9 @@ static int gas_query_tx(struct gas_query *gas, struct gas_query_pending *query,
 	};
 
 	wpa_printf(MSG_DEBUG, "GAS: Send action frame to " MACSTR " len=%u "
-		   "freq=%d prot=%d", MAC2STR(query->addr),
-		   (unsigned int) wpabuf_len(req), query->freq, prot);
+		   "freq=%d prot=%d using src addr " MACSTR,
+		   MAC2STR(query->addr), (unsigned int) wpabuf_len(req),
+		   query->freq, prot, MAC2STR(query->sa));
 	if (prot) {
 		u8 *categ = wpabuf_mhead_u8(req);
 		*categ = WLAN_ACTION_PROTECTED_DUAL;
@@ -295,10 +300,12 @@ static int gas_query_tx(struct gas_query *gas, struct gas_query_pending *query,
 		bssid = query->addr;
 	else
 		bssid = wildcard_bssid;
+
 	res = offchannel_send_action(gas->wpa_s, query->freq, query->addr,
-				     gas->wpa_s->own_addr, bssid,
-				     wpabuf_head(req), wpabuf_len(req),
-				     wait_time, gas_query_tx_status, 0);
+				     query->sa, bssid, wpabuf_head(req),
+				     wpabuf_len(req), wait_time,
+				     gas_query_tx_status, 0);
+
 	if (res == 0)
 		query->offchannel_tx_started = 1;
 	return res;
@@ -725,6 +732,58 @@ static int gas_query_new_dialog_token(struct gas_query *gas, const u8 *dst)
 }
 
 
+static int gas_query_set_sa(struct gas_query *gas,
+			    struct gas_query_pending *query)
+{
+	struct wpa_supplicant *wpa_s = gas->wpa_s;
+	struct os_reltime now;
+
+	if (!wpa_s->conf->gas_rand_mac_addr ||
+	    !(wpa_s->current_bss ?
+	      (wpa_s->drv_flags &
+	       WPA_DRIVER_FLAGS_MGMT_TX_RANDOM_TA_CONNECTED) :
+	      (wpa_s->drv_flags & WPA_DRIVER_FLAGS_MGMT_TX_RANDOM_TA))) {
+		/* Use own MAC address as the transmitter address */
+		os_memcpy(query->sa, wpa_s->own_addr, ETH_ALEN);
+		return 0;
+	}
+
+	os_get_reltime(&now);
+
+	if (wpa_s->conf->gas_rand_mac_addr == gas->last_rand_sa_type &&
+	    gas->last_mac_addr_rand.sec != 0 &&
+	    !os_reltime_expired(&now, &gas->last_mac_addr_rand,
+				wpa_s->conf->gas_rand_addr_lifetime)) {
+		wpa_printf(MSG_DEBUG,
+			   "GAS: Use the previously selected random transmitter address "
+			   MACSTR, MAC2STR(gas->rand_addr));
+		os_memcpy(query->sa, gas->rand_addr, ETH_ALEN);
+		return 0;
+	}
+
+	if (wpa_s->conf->gas_rand_mac_addr == 1 &&
+	    random_mac_addr(gas->rand_addr) < 0) {
+		wpa_printf(MSG_ERROR, "GAS: Failed to get random address");
+		return -1;
+	}
+
+	if (wpa_s->conf->gas_rand_mac_addr == 2 &&
+	    random_mac_addr_keep_oui(gas->rand_addr) < 0) {
+		wpa_printf(MSG_ERROR,
+			   "GAS: Failed to get random address with same OUI");
+		return -1;
+	}
+
+	wpa_printf(MSG_DEBUG, "GAS: Use a new random transmitter address "
+		   MACSTR, MAC2STR(gas->rand_addr));
+	os_memcpy(query->sa, gas->rand_addr, ETH_ALEN);
+	os_get_reltime(&gas->last_mac_addr_rand);
+	gas->last_rand_sa_type = wpa_s->conf->gas_rand_mac_addr;
+
+	return 0;
+}
+
+
 /**
  * gas_query_req - Request a GAS query
  * @gas: GAS query data from gas_query_init()
@@ -759,6 +818,10 @@ int gas_query_req(struct gas_query *gas, const u8 *dst, int freq,
 		return -1;
 
 	query->gas = gas;
+	if (gas_query_set_sa(gas, query)) {
+		os_free(query);
+		return -1;
+	}
 	os_memcpy(query->addr, dst, ETH_ALEN);
 	query->dialog_token = dialog_token;
 	query->freq = freq;

wpa_supplicant/wpa_supplicant.conf

@@ -422,6 +422,15 @@ fast_reauth=1
 # 2 = like 1, but maintain OUI (with local admin bit set)
 #preassoc_mac_addr=0
 
+# MAC address policy for GAS operations
+# 0 = use permanent MAC address
+# 1 = use random MAC address
+# 2 = like 1, but maintain OUI (with local admin bit set)
+#gas_rand_mac_addr=0
+
+# Lifetime of GAS random MAC address in seconds (default: 60)
+#gas_rand_addr_lifetime=60
+
 # Interworking (IEEE 802.11u)
 
 # Enable Interworking