130 lines
		
	
	
		
			4.1 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			130 lines
		
	
	
		
			4.1 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
# Global configuration for the SSH client.
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{ config, lib, pkgs, ... }:
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with lib;
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let cfg  = config.programs.ssh;
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    cfgd = config.services.openssh;
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in
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{
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  ###### interface
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  options = {
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    programs.ssh = {
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      forwardX11 = mkOption {
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        type = types.bool;
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        default = false;
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        description = ''
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          Whether to request X11 forwarding on outgoing connections by default.
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          This is useful for running graphical programs on the remote machine and have them display to your local X11 server.
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          Historically, this value has depended on the value used by the local sshd daemon, but there really isn't a relation between the two.
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          Note: there are some security risks to forwarding an X11 connection.
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          NixOS's X server is built with the SECURITY extension, which prevents some obvious attacks.
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          To enable or disable forwarding on a per-connection basis, see the -X and -x options to ssh.
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          The -Y option to ssh enables trusted forwarding, which bypasses the SECURITY extension.
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        '';
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      };
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      setXAuthLocation = mkOption {
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        type = types.bool;
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        default = config.services.xserver.enable;
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        description = ''
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          Whether to set the path to <command>xauth</command> for X11-forwarded connections.
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          This causes a dependency on X11 packages.
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        '';
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      };
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      extraConfig = mkOption {
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        type = types.lines;
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        default = "";
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        description = ''
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          Extra configuration text appended to <filename>ssh_config</filename>.
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          See <citerefentry><refentrytitle>ssh_config</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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          for help.
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        '';
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      };
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      startAgent = mkOption {
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        type = types.bool;
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        default = true;
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        description = ''
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          Whether to start the OpenSSH agent when you log in.  The OpenSSH agent
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          remembers private keys for you so that you don't have to type in
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          passphrases every time you make an SSH connection.  Use
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          <command>ssh-add</command> to add a key to the agent.
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        '';
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      };
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      agentTimeout = mkOption {
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        type = types.nullOr types.string;
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        default = "1h";
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        description = ''
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          How long to keep the private keys in memory. Use null to keep them forever.
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        '';
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      };
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      package = mkOption {
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        default = pkgs.openssh;
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        description = ''
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          The package used for the openssh client and daemon.
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        '';
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      };
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    };
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  };
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  config = {
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    assertions = singleton
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      { assertion = cfg.forwardX11 -> cfg.setXAuthLocation;
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        message = "cannot enable X11 forwarding without setting XAuth location";
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      };
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    environment.etc =
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      [ { # SSH configuration.  Slight duplication of the sshd_config
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          # generation in the sshd service.
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          source = pkgs.writeText "ssh_config" ''
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            AddressFamily ${if config.networking.enableIPv6 then "any" else "inet"}
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            ${optionalString cfg.setXAuthLocation ''
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              XAuthLocation ${pkgs.xorg.xauth}/bin/xauth
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            ''}
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            ForwardX11 ${if cfg.forwardX11 then "yes" else "no"}
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            ${cfg.extraConfig}
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          '';
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          target = "ssh/ssh_config";
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        }
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      ];
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    # FIXME: this should really be socket-activated for über-awesomeness.
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    systemd.user.services.ssh-agent =
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      { enable = cfg.startAgent;
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        description = "SSH Agent";
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        wantedBy = [ "default.target" ];
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        serviceConfig =
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          { ExecStartPre = "${pkgs.coreutils}/bin/rm -f %t/ssh-agent";
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            ExecStart =
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                "${cfg.package}/bin/ssh-agent " +
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                optionalString (cfg.agentTimeout != null) ("-t ${cfg.agentTimeout} ") +
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                "-a %t/ssh-agent";
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            StandardOutput = "null";
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            Type = "forking";
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            Restart = "on-failure";
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            SuccessExitStatus = "0 2";
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          };
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      };
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    environment.extraInit = optionalString cfg.startAgent
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      ''
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        if [ -z "$SSH_AUTH_SOCK" -a -n "$XDG_RUNTIME_DIR" ]; then
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          export SSH_AUTH_SOCK="$XDG_RUNTIME_DIR/ssh-agent"
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        fi
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      '';
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  };
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}
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