P2P: Support random device address

To enhance privacy, generate a random device address for P2P interface.
If there is no saved persistent group, it generate a new random MAC
address on bringing up p2p0. If there is saved persistent group, it will
use last MAC address to avoid breaking group reinvoke behavior.

There are two configurations are introduced:
* p2p_device_random_mac_addr
  enable device random MAC address feature, default disable.
* p2p_device_persistent_mac_addr
  store last used random MAC address.

Signed-off-by: Jimmy Chen <jimmycmchen@google.com>

wpa_supplicant/config.c

@@ -4528,6 +4528,21 @@ static int wpa_config_process_p2p_no_go_freq(
 	return 0;
 }
 
+
+static int wpa_config_process_p2p_device_persistent_mac_addr(
+	const struct global_parse_data *data,
+	struct wpa_config *config, int line, const char *pos)
+{
+	if (hwaddr_aton2(pos, config->p2p_device_persistent_mac_addr) < 0) {
+		wpa_printf(MSG_ERROR,
+			   "Line %d: Invalid p2p_device_persistent_mac_addr '%s'",
+			   line, pos);
+		return -1;
+	}
+
+	return 0;
+}
+
 #endif /* CONFIG_P2P */
 
 
@@ -4770,6 +4785,8 @@ static const struct global_parse_data global_fields[] = {
 	{ IPV4(ip_addr_start), 0 },
 	{ IPV4(ip_addr_end), 0 },
 	{ INT_RANGE(p2p_cli_probe, 0, 1), 0 },
+	{ INT(p2p_device_random_mac_addr), 0 },
+	{ FUNC(p2p_device_persistent_mac_addr), 0 },
 #endif /* CONFIG_P2P */
 	{ FUNC(country), CFG_CHANGED_COUNTRY },
 	{ INT(bss_max_count), 0 },

wpa_supplicant/config.h

@@ -1488,6 +1488,25 @@ struct wpa_config {
 	 * 1 = enabled (true)
 	 */
 	int coloc_intf_reporting;
+
+	/**
+	 * p2p_device_random_mac_addr - P2P Device MAC address policy default
+	 *
+	 * 0 = use permanent MAC address
+	 * 1 = use random MAC address on creating the interface if there is no
+	 * persistent groups.
+	 *
+	 * By default, permanent MAC address is used.
+	 */
+	int p2p_device_random_mac_addr;
+
+	/**
+	 * p2p_device_persistent_mac_addr - Record last used MAC address
+	 *
+	 * If there are saved persistent groups, P2P cannot generate another
+	 * random MAC address, and need to restore to last used MAC address.
+	 */
+	u8 p2p_device_persistent_mac_addr[ETH_ALEN];
 };
 
 

wpa_supplicant/config_file.c

@@ -1529,6 +1529,12 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 	if (config->coloc_intf_reporting)
 		fprintf(f, "coloc_intf_reporting=%d\n",
 			config->coloc_intf_reporting);
+	if (config->p2p_device_random_mac_addr)
+		fprintf(f, "p2p_device_random_mac_addr=%d\n",
+			config->p2p_device_random_mac_addr);
+	if (!is_zero_ether_addr(config->p2p_device_persistent_mac_addr))
+		fprintf(f, "p2p_device_persistent_mac_addr=" MACSTR "\n",
+			MAC2STR(config->p2p_device_persistent_mac_addr));
 }
 
 #endif /* CONFIG_NO_CONFIG_WRITE */

wpa_supplicant/p2p_supplicant.c

@@ -4330,6 +4330,54 @@ static int wpas_p2p_get_pref_freq_list(void *ctx, int go,
 }
 
 
+int wpas_p2p_mac_setup(struct wpa_supplicant *wpa_s)
+{
+	u8 addr[ETH_ALEN] = {0};
+
+	if (wpa_s->conf->p2p_device_random_mac_addr == 0)
+		return 0;
+
+	if (!wpa_s->conf->ssid) {
+		if (random_mac_addr(addr) < 0) {
+			wpa_msg(wpa_s, MSG_INFO,
+				"Failed to generate random MAC address");
+			return -EINVAL;
+		}
+
+		/* Store generated MAC address. */
+		os_memcpy(wpa_s->conf->p2p_device_persistent_mac_addr, addr,
+			  ETH_ALEN);
+	} else {
+		/* If there are existing saved groups, restore last MAC address.
+		 * if there is no last used MAC address, the last one is
+		 * factory MAC. */
+		if (is_zero_ether_addr(
+			    wpa_s->conf->p2p_device_persistent_mac_addr))
+			return 0;
+		os_memcpy(addr, wpa_s->conf->p2p_device_persistent_mac_addr,
+			  ETH_ALEN);
+		wpa_msg(wpa_s, MSG_DEBUG, "Restore last used MAC address.");
+	}
+
+	if (wpa_drv_set_mac_addr(wpa_s, addr) < 0) {
+		wpa_msg(wpa_s, MSG_INFO,
+			"Failed to set random MAC address");
+		return -EINVAL;
+	}
+
+	if (wpa_supplicant_update_mac_addr(wpa_s) < 0) {
+		wpa_msg(wpa_s, MSG_INFO,
+			"Could not update MAC address information");
+		return -EINVAL;
+	}
+
+	wpa_msg(wpa_s, MSG_DEBUG, "Using random MAC address " MACSTR,
+		MAC2STR(addr));
+
+	return 0;
+}
+
+
 /**
  * wpas_p2p_init - Initialize P2P module for %wpa_supplicant
  * @global: Pointer to global data from wpa_supplicant_init()
@@ -4350,6 +4398,12 @@ int wpas_p2p_init(struct wpa_global *global, struct wpa_supplicant *wpa_s)
 	if (global->p2p)
 		return 0;
 
+	if (wpas_p2p_mac_setup(wpa_s) < 0) {
+		wpa_msg(wpa_s, MSG_ERROR,
+			"Failed to initialize P2P random MAC address.");
+		return -1;
+	}
+
 	os_memset(&p2p, 0, sizeof(p2p));
 	p2p.cb_ctx = wpa_s;
 	p2p.debug_print = wpas_p2p_debug_print;

wpa_supplicant/p2p_supplicant.h

@@ -211,6 +211,7 @@ int wpas_p2p_lo_start(struct wpa_supplicant *wpa_s, unsigned int freq,
 		      unsigned int period, unsigned int interval,
 		      unsigned int count);
 int wpas_p2p_lo_stop(struct wpa_supplicant *wpa_s);
+int wpas_p2p_mac_setup(struct wpa_supplicant *wpa_s);
 
 #else /* CONFIG_P2P */