better module

modules/zwave-js-ui.nix

@@ -16,13 +16,15 @@ in
 {
   options.services.zwave-js-ui = {
     enable = mkEnableOption "zwave-js-ui";
-    store = mkOption {
+    serialPort = mkOption {
       type = types.path;
-      default = "/var/lib/zwave-js-ui";
       description = ''
-        Where zwave-js-ui information will be stored
+       Serial port for the Z-Wave controller.
-      '';
+
-    };
+       Used for permissions only; must be additionally set in the application
+     '';
+     example = "/dev/ttyUSB0";
+   };
   };
   config = mkIf cfg.enable {
     assertions = [
@@ -33,10 +35,48 @@ in
     ];
     systemd.services.zwave-js-ui = {
       environment = {
-        STORE_DIR = cfg.store;
+        STORE_DIR = "/var/lib/zwave-js-ui";
-        ZWAVEJS_EXTERNAL_CONFIG = "${cfg.store}/.config-db";
+        ZWAVEJS_EXTERNAL_CONFIG = "/var/lib/zwave-js-ui/.config-db";
       };
       script = "${pkgs.zwave-js-ui}/bin/zwave-js-ui";
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        RuntimeDirectory = "zwave-js-ui";
+        StateDirectory = "zwave-js-ui";
+        RootDirectory = "/run/zwave-js-ui";
+        BindReadOnlyPaths = [ "/etc" "/nix/store" ];
+        BindPaths = [ "/var/lib/zwave-js-ui" ];
+        DeviceAllow = [ cfg.serialPort ];
+        DynamicUser = true;
+        SupplementaryGroups = [ "dialout" ];
+        CapabilityBoundingSet = "";
+        RestrictAddressFamilies = "AF_INET AF_INET6";
+        DevicePolicy = "closed";
+        LockPersonality = true;
+        MemoryDenyWriteExecute = false;
+        NoNewPrivileges = true;
+        PrivateUsers = true;
+        PrivateTmp = true;
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectProc = "invisible";
+        ProcSubset = "pid";
+        RemoveIPC = true;
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        SystemCallArchitectures = "native";
+        SystemCallFilter = [
+          "@system-service @pkey"
+          "~@privileged @resources"
+        ];
+        UMask = "0077";
+      };
     };
   };
 }