nixos/homepage-dashboard: harden service (#377886)

nixos/modules/services/misc/homepage-dashboard.nix

@@ -232,12 +232,50 @@ in
 
       serviceConfig = {
         Type = "simple";
-        DynamicUser = true;
         EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
         StateDirectory = "homepage-dashboard";
         CacheDirectory = "homepage-dashboard";
         ExecStart = lib.getExe cfg.package;
         Restart = "on-failure";
+
+        # hardening
+        DynamicUser = true;
+        DevicePolicy = "closed";
+        CapabilityBoundingSet = "";
+        RestrictAddressFamilies = [
+          "AF_INET"
+          "AF_INET6"
+          "AF_UNIX"
+          "AF_NETLINK"
+        ];
+        DeviceAllow = "";
+        NoNewPrivileges = true;
+        PrivateDevices = true;
+        PrivateMounts = true;
+        PrivateTmp = true;
+        PrivateUsers = true;
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectSystem = "strict";
+        LockPersonality = true;
+        RemoveIPC = true;
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        SystemCallArchitectures = "native";
+        SystemCallFilter = [
+          "@system-service"
+          "~@resources"
+        ];
+        ProtectProc = "invisible";
+        ProtectHostname = true;
+        UMask = "0077";
+        # cpu widget requires access to /proc
+        ProcSubset = if lib.any (widget: widget.resources.cpu or false) cfg.widgets then "all" else "pid";
       };
 
       enableStrictShellChecks = true;