Fortify

Lets you run graphical applications as another user in an Android-like sandbox environment (WIP) with a nice NixOS module to configure target users and provide launchers and desktop files for your privileged user.

Why would you want this?

• It protects the desktop environment from applications.

• It protects applications from each other.

• It provides UID isolation on top of the standard application sandbox (WIP).

There are a few different things to set up for this to work:

• A set of users, each for a group of applications that should be allowed access to each other

• A tool to switch users, currently sudo and machinectl are supported.

• If you are running NixOS, the module in this repository can take care of launchers and desktop files in the privileged user's environment, as well as packages and extra home-manager configuration for target users.

If you have a flakes-enabled nix environment, you can try out the tool by running:

nix run git+https://git.ophivana.moe/cat/fortify -- -h

Module usage

The NixOS module currently requires home-manager and impermanence to function correctly.

To use the module, import it into your configuration with

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";

    fortify = {
      url = "git+https://git.ophivana.moe/cat/fortify";

      # Optional but recommended to limit the size of your system closure.
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = { self, nixpkgs, fortify, ... }:
  {
    nixosConfigurations.fortify = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [
        fortify.nixosModules.fortify
      ];
    };
  };
}

This adds the environment.fortify option:

{ pkgs, ... }:

{
  environment.fortify = {
    enable = true;
    user = "nixos";
    shell = "zsh";
    stateDir = "/var/lib/persist/module";
    target = {
      chronos = {
        launchers = {
          weechat.method = "sudo";
          claws-mail.pulse = false;
          discord = {
            command = "vesktop --ozone-platform-hint=wayland";
            share = pkgs.vesktop;
          };
        };
        packages = with pkgs; [
          weechat
          claws-mail
          vesktop
        ];
        persistence.directories = [
          ".config/weechat"
          ".claws-mail"
          ".config/vesktop"
        ];
        extraConfig = {
          programs.looking-glass-client.enable = true;
        };
      };
    };
  };
}

• enable determines whether the module should be enabled or not. Useful when sharing configurations between graphical and headless systems. Defaults to false.

• user specifies the privileged user with access to fortified applications.

• shell is the shell used to run the launch command, required for sourcing the home-manager environment.

• stateDir is the path to your persistent storage location. It is directly passed through to the impermanence module.

• target is an attribute set of submodules, where the attribute name is the username of the unprivileged target user.

  The available options are:

  • packages, the list of packages to make available in the target user's environment.

  • persistence, user persistence attribute set passed to impermanence.

  • extraConfig, extra home-manager configuration for the target user.

  • launchers, attribute set where the attribute name is the name of the launcher.

    The available options are:

    • command, the command to run as the target user. Defaults to launcher name.

    • pulse, whether to share the PulseAudio socket and cookie.

    • share, package containing desktop/icon files. Defaults to launcher name.

    • method, the launch method for the sandboxed program, can be "fortify", "fortify-sudo", "sudo".