Bluetooth: GATT: Allow to tune writable device appearance permissions

This allows to select if device appearance requires encryption or
authentication or none. This makes it similar to what is implemented
for device name characteristic.

Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>

Author: sjanc

subsys/bluetooth/host/Kconfig

@@ -871,10 +871,6 @@ config BT_DEVICE_APPEARANCE_DYNAMIC
 	  Enables use of bt_set_appearance.
 	  If CONFIG_BT_SETTINGS is set, the appearance is persistently stored.
 
-config BT_DEVICE_APPEARANCE_GATT_WRITABLE
-	bool "Allow authenticated peers to set GAP Appearance"
-	depends on BT_DEVICE_APPEARANCE_DYNAMIC
-
 config BT_DEVICE_APPEARANCE
 	int "Bluetooth device appearance"
 	range 0 $(UINT16_MAX)

subsys/bluetooth/host/Kconfig.gatt

@@ -287,6 +287,34 @@ config DEVICE_NAME_GATT_WRITABLE_AUTHEN
 endchoice  #BT_DEVICE_NAME_GATT_WRITABLE_SECURITY
 endif #BT_DEVICE_NAME_GATT_WRITABLE
 
+config BT_DEVICE_APPEARANCE_GATT_WRITABLE
+	bool "Allow to write GAP Appearance by remote GATT clients"
+	depends on BT_DEVICE_APPEARANCE_DYNAMIC
+	default y
+	help
+	  Enabling this option allows remote GATT clients to write to device
+	  appearance GAP characteristic.
+
+if BT_DEVICE_APPEARANCE_GATT_WRITABLE
+choice BT_DEVICE_APPEARANCE_GATT_WRITABLE
+	prompt "Security requirements"
+	default DEVICE_APPEARANCE_GATT_WRITABLE_AUTHEN
+	help
+	  Select security requirementsf for writing device name by remote GATT
+	  clients.
+
+config BT_DEVICE_APPEARANCE_GATT_WRITABLE_NONE
+	bool "No requirements"
+
+config BT_DEVICE_APPEARANCE_GATT_WRITABLE_ENCRYPT
+	bool "Encryption required"
+
+config DEVICE_APPEARANCE_GATT_WRITABLE_AUTHEN
+	bool "Encryption and authentication required"
+
+endchoice  #BT_DEVICE_APPEARANCE_GATT_WRITABLE
+endif #BT_DEVICE_APPEARANCE_GATT_WRITABLE
+
 config BT_GATT_AUTHORIZATION_CUSTOM
 	bool "Custom authorization of GATT operations"
 	help

subsys/bluetooth/host/gatt.c

@@ -174,9 +174,15 @@ static ssize_t write_appearance(struct bt_conn *conn, const struct bt_gatt_attr
 }
 #endif /* CONFIG_BT_DEVICE_APPEARANCE_GATT_WRITABLE */
 
-#if CONFIG_BT_DEVICE_APPEARANCE_GATT_WRITABLE
+#if defined(CONFIG_BT_DEVICE_APPEARANCE_GATT_WRITABLE)
 	#define GAP_APPEARANCE_PROPS (BT_GATT_CHRC_READ | BT_GATT_CHRC_WRITE)
+#if defined(CONFIG_DEVICE_APPEARANCE_GATT_WRITABLE_AUTHEN)
 	#define GAP_APPEARANCE_PERMS (BT_GATT_PERM_READ | BT_GATT_PERM_WRITE_AUTHEN)
+#elif defined(CONFIG_BT_DEVICE_APPEARANCE_GATT_WRITABLE_ENCRYPT)
+	#define GAP_APPEARANCE_PERMS (BT_GATT_PERM_READ | BT_GATT_PERM_WRITE_ENCRYPT)
+#else
+	#define GAP_APPEARANCE_PERMS (BT_GATT_PERM_READ | BT_GATT_PERM_WRITE)
+#endif
 	#define GAP_APPEARANCE_WRITE_HANDLER write_appearance
 #else
 	#define GAP_APPEARANCE_PROPS BT_GATT_CHRC_READ