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-rw-r--r--nixpkgs/nixos/modules/services/x11/display-managers/gdm.nix296
1 files changed, 296 insertions, 0 deletions
diff --git a/nixpkgs/nixos/modules/services/x11/display-managers/gdm.nix b/nixpkgs/nixos/modules/services/x11/display-managers/gdm.nix
new file mode 100644
index 000000000000..3f1669d08516
--- /dev/null
+++ b/nixpkgs/nixos/modules/services/x11/display-managers/gdm.nix
@@ -0,0 +1,296 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.xserver.displayManager;
+  gdm = pkgs.gnome3.gdm;
+
+  xSessionWrapper = if (cfg.setupCommands == "") then null else
+    pkgs.writeScript "gdm-x-session-wrapper" ''
+      #!${pkgs.bash}/bin/bash
+      ${cfg.setupCommands}
+      exec "$@"
+    '';
+
+  # Solves problems like:
+  # https://wiki.archlinux.org/index.php/Talk:Bluetooth_headset#GDMs_pulseaudio_instance_captures_bluetooth_headset
+  # Instead of blacklisting plugins, we use Fedora's PulseAudio configuration for GDM:
+  # https://src.fedoraproject.org/rpms/gdm/blob/master/f/default.pa-for-gdm
+  pulseConfig = pkgs.writeText "default.pa" ''
+    load-module module-device-restore
+    load-module module-card-restore
+    load-module module-udev-detect
+    load-module module-native-protocol-unix
+    load-module module-default-device-restore
+    load-module module-rescue-streams
+    load-module module-always-sink
+    load-module module-intended-roles
+    load-module module-suspend-on-idle
+    load-module module-position-event-sounds
+  '';
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.xserver.displayManager.gdm = {
+
+      enable = mkEnableOption ''
+        GDM as the display manager.
+        <emphasis>GDM in NixOS is not well-tested with desktops other
+        than GNOME, so use with caution, as it could render the
+        system unusable.</emphasis>
+      '';
+
+      debug = mkEnableOption ''
+        debugging messages in GDM
+      '';
+
+      autoLogin = mkOption {
+        default = {};
+        description = ''
+          Auto login configuration attrset.
+        '';
+
+        type = types.submodule {
+          options = {
+            enable = mkOption {
+              type = types.bool;
+              default = false;
+              description = ''
+                Automatically log in as the sepecified <option>autoLogin.user</option>.
+              '';
+            };
+
+            user = mkOption {
+              type = types.nullOr types.str;
+              default = null;
+              description = ''
+                User to be used for the autologin.
+              '';
+            };
+
+            delay = mkOption {
+              type = types.int;
+              default = 0;
+              description = ''
+                Seconds of inactivity after which the autologin will be performed.
+              '';
+            };
+
+          };
+        };
+      };
+
+      wayland = mkOption {
+        default = true;
+        description = ''
+          Allow GDM run on Wayland instead of Xserver
+        '';
+        type = types.bool;
+      };
+
+      autoSuspend = mkOption {
+        default = true;
+        description = ''
+          Suspend the machine after inactivity.
+        '';
+        type = types.bool;
+      };
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.gdm.enable {
+
+    assertions = [
+      { assertion = cfg.gdm.autoLogin.enable -> cfg.gdm.autoLogin.user != null;
+        message = "GDM auto-login requires services.xserver.displayManager.gdm.autoLogin.user to be set";
+      }
+    ];
+
+    services.xserver.displayManager.lightdm.enable = false;
+
+    users.users.gdm =
+      { name = "gdm";
+        uid = config.ids.uids.gdm;
+        group = "gdm";
+        home = "/run/gdm";
+        description = "GDM user";
+      };
+
+    users.groups.gdm.gid = config.ids.gids.gdm;
+
+    # GDM needs different xserverArgs, presumable because using wayland by default.
+    services.xserver.tty = null;
+    services.xserver.display = null;
+    services.xserver.verbose = null;
+
+    services.xserver.displayManager.job =
+      {
+        environment = {
+          GDM_X_SERVER_EXTRA_ARGS = toString
+            (filter (arg: arg != "-terminate") cfg.xserverArgs);
+          XDG_DATA_DIRS = "${cfg.session.desktops}/share/";
+          # Find the mouse
+          XCURSOR_PATH = "~/.icons:${pkgs.gnome3.adwaita-icon-theme}/share/icons";
+        } // optionalAttrs (xSessionWrapper != null) {
+          # Make GDM use this wrapper before running the session, which runs the
+          # configured setupCommands. This relies on a patched GDM which supports
+          # this environment variable.
+          GDM_X_SESSION_WRAPPER = "${xSessionWrapper}";
+        };
+        execCmd = "exec ${gdm}/bin/gdm";
+        preStart = optionalString config.hardware.pulseaudio.enable ''
+          mkdir -p /run/gdm/.config/pulse
+          ln -sf ${pulseConfig} /run/gdm/.config/pulse/default.pa
+          chown -R gdm:gdm /run/gdm/.config
+        '';
+      };
+
+    # Because sd_login_monitor_new requires /run/systemd/machines
+    systemd.services.display-manager.wants = [ "systemd-machined.service" ];
+    systemd.services.display-manager.after = [
+      "rc-local.service"
+      "systemd-machined.service"
+      "systemd-user-sessions.service"
+    ];
+
+    systemd.services.display-manager.serviceConfig = {
+      # Restart = "always"; - already defined in xserver.nix
+      KillMode = "mixed";
+      IgnoreSIGPIPE = "no";
+      BusName = "org.gnome.DisplayManager";
+      StandardOutput = "syslog";
+      StandardError = "inherit";
+    };
+
+    systemd.services.display-manager.path = [ pkgs.gnome3.gnome-session ];
+
+    # Allow choosing an user account
+    services.accounts-daemon.enable = true;
+
+    services.dbus.packages = [ gdm ];
+
+    systemd.user.services.dbus.wantedBy = [ "default.target" ];
+
+    programs.dconf.profiles.gdm =
+    let
+      customDconf = pkgs.writeTextFile {
+        name = "gdm-dconf";
+        destination = "/dconf/gdm-custom";
+        text = ''
+          ${optionalString (!cfg.gdm.autoSuspend) ''
+            [org/gnome/settings-daemon/plugins/power]
+            sleep-inactive-ac-type='nothing'
+            sleep-inactive-battery-type='nothing'
+            sleep-inactive-ac-timeout=0
+            sleep-inactive-battery-timeout=0
+          ''}
+        '';
+      };
+
+      customDconfDb = pkgs.stdenv.mkDerivation {
+        name = "gdm-dconf-db";
+        buildCommand = ''
+          ${pkgs.gnome3.dconf}/bin/dconf compile $out ${customDconf}/dconf
+        '';
+      };
+    in pkgs.stdenv.mkDerivation {
+      name = "dconf-gdm-profile";
+      buildCommand = ''
+        # Check that the GDM profile starts with what we expect.
+        if [ $(head -n 1 ${gdm}/share/dconf/profile/gdm) != "user-db:user" ]; then
+          echo "GDM dconf profile changed, please update gdm.nix"
+          exit 1
+        fi
+        # Insert our custom DB behind it.
+        sed '2ifile-db:${customDconfDb}' ${gdm}/share/dconf/profile/gdm > $out
+      '';
+    };
+
+    # Use AutomaticLogin if delay is zero, because it's immediate.
+    # Otherwise with TimedLogin with zero seconds the prompt is still
+    # presented and there's a little delay.
+    environment.etc."gdm/custom.conf".text = ''
+      [daemon]
+      WaylandEnable=${if cfg.gdm.wayland then "true" else "false"}
+      ${optionalString cfg.gdm.autoLogin.enable (
+        if cfg.gdm.autoLogin.delay > 0 then ''
+          TimedLoginEnable=true
+          TimedLogin=${cfg.gdm.autoLogin.user}
+          TimedLoginDelay=${toString cfg.gdm.autoLogin.delay}
+        '' else ''
+          AutomaticLoginEnable=true
+          AutomaticLogin=${cfg.gdm.autoLogin.user}
+        '')
+      }
+
+      [security]
+
+      [xdmcp]
+
+      [greeter]
+
+      [chooser]
+
+      [debug]
+      ${optionalString cfg.gdm.debug "Enable=true"}
+    '';
+
+    environment.etc."gdm/Xsession".source = config.services.xserver.displayManager.session.wrapper;
+
+    # GDM LFS PAM modules, adapted somehow to NixOS
+    security.pam.services = {
+      gdm-launch-environment.text = ''
+        auth     required       pam_succeed_if.so audit quiet_success user = gdm
+        auth     optional       pam_permit.so
+
+        account  required       pam_succeed_if.so audit quiet_success user = gdm
+        account  sufficient     pam_unix.so
+
+        password required       pam_deny.so
+
+        session  required       pam_succeed_if.so audit quiet_success user = gdm
+        session  required       pam_env.so envfile=${config.system.build.pamEnvironment}
+        session  optional       ${pkgs.systemd}/lib/security/pam_systemd.so
+        session  optional       pam_keyinit.so force revoke
+        session  optional       pam_permit.so
+      '';
+
+      gdm-password.text = ''
+        auth      substack      login
+        account   include       login
+        password  substack      login
+        session   include       login
+      '';
+
+      gdm-autologin.text = ''
+        auth      requisite     pam_nologin.so
+
+        auth      required      pam_succeed_if.so uid >= 1000 quiet
+        auth      required      pam_permit.so
+
+        account   sufficient    pam_unix.so
+
+        password  requisite     pam_unix.so nullok sha512
+
+        session   optional      pam_keyinit.so revoke
+        session   include       login
+      '';
+
+    };
+
+  };
+
+}