P2P: support random interface address

To enhance privacy, generate a random interface for each group.

There are two configurations are introduced:
* p2p_interface_random_mac_addr
  enable interface random MAC address feature, default disable.

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

wpa_supplicant/config.c

@@ -4787,6 +4787,7 @@ static const struct global_parse_data global_fields[] = {
 	{ INT_RANGE(p2p_cli_probe, 0, 1), 0 },
 	{ INT(p2p_device_random_mac_addr), 0 },
 	{ FUNC(p2p_device_persistent_mac_addr), 0 },
+	{ INT(p2p_interface_random_mac_addr), 0 },
 #endif /* CONFIG_P2P */
 	{ FUNC(country), CFG_CHANGED_COUNTRY },
 	{ INT(bss_max_count), 0 },

wpa_supplicant/config.h

@@ -1507,6 +1507,16 @@ struct wpa_config {
 	 * random MAC address, and need to restore to last used MAC address.
 	 */
 	u8 p2p_device_persistent_mac_addr[ETH_ALEN];
+
+	/**
+	 * p2p_interface_random_mac_addr - P2P Interface MAC address policy default
+	 *
+	 * 0 = use permanent MAC address
+	 * 1 = use random MAC address on creating the interface.
+	 *
+	 * By default, permanent MAC address is used.
+	 */
+	int p2p_interface_random_mac_addr;
 };
 
 

wpa_supplicant/config_file.c

@@ -1535,6 +1535,9 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 	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));
+	if (config->p2p_interface_random_mac_addr)
+		fprintf(f, "p2p_interface_random_mac_addr=%d\n",
+			config->p2p_interface_random_mac_addr);
 }
 
 #endif /* CONFIG_NO_CONFIG_WRITE */

wpa_supplicant/p2p_supplicant.c

@@ -2076,6 +2076,13 @@ static int wpas_p2p_add_group_interface(struct wpa_supplicant *wpa_s,
 		return -1;
 	}
 
+	if (wpa_s->conf->p2p_interface_random_mac_addr) {
+		random_mac_addr(wpa_s->pending_interface_addr);
+		wpa_printf(MSG_DEBUG, "P2P: Generate random MAC address " MACSTR
+			   " for the group",
+			   MAC2STR(wpa_s->pending_interface_addr));
+	}
+
 	if (force_ifname[0]) {
 		wpa_printf(MSG_DEBUG, "P2P: Driver forced interface name %s",
 			   force_ifname);
@@ -2154,6 +2161,29 @@ wpas_p2p_init_group_interface(struct wpa_supplicant *wpa_s, int go)
 
 	wpas_p2p_clone_config(group_wpa_s, wpa_s);
 
+	if (wpa_s->conf->p2p_interface_random_mac_addr) {
+		if (wpa_drv_set_mac_addr(group_wpa_s,
+					 wpa_s->pending_interface_addr) < 0) {
+			wpa_msg(group_wpa_s, MSG_INFO,
+				"Failed to set random MAC address");
+			wpa_supplicant_remove_iface(wpa_s->global, group_wpa_s,
+						    0);
+			return NULL;
+		}
+
+		if (wpa_supplicant_update_mac_addr(group_wpa_s) < 0) {
+			wpa_msg(group_wpa_s, MSG_INFO,
+				"Could not update MAC address information");
+			wpa_supplicant_remove_iface(wpa_s->global, group_wpa_s,
+						    0);
+			return NULL;
+		}
+
+		wpa_printf(MSG_DEBUG, "P2P: Using random MAC address " MACSTR
+			   " for the group",
+			   MAC2STR(wpa_s->pending_interface_addr));
+	}
+
 	return group_wpa_s;
 }