;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019, 2020 L p R n d n <guix@lprndn.info>
;;; Copyright © 2020 Ricardo Wurmus <rekado@elephly.net>
;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu services lightdm)
#:use-module (gnu artwork)
#:use-module (gnu packages admin)
#:use-module (gnu packages display-managers)
#:use-module (gnu packages freedesktop)
#:use-module (gnu packages gnome)
#:use-module (gnu packages vnc)
#:use-module (gnu packages xorg)
#:use-module (gnu services configuration)
#:use-module (gnu services dbus)
#:use-module (gnu services desktop)
#:use-module (gnu services shepherd)
#:use-module (gnu services xorg)
#:use-module (gnu services)
#:use-module (gnu system pam)
#:use-module (gnu system shadow)
#:use-module (guix diagnostics)
#:use-module (guix gexp)
#:use-module (guix i18n)
#:use-module (guix records)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:export (lightdm-seat-configuration
lightdm-seat-configuration?
lightdm-seat-configuration-name
lightdm-seat-configuration-type
lightdm-seat-configuration-user-session
lightdm-seat-configuration-autologin-user
lightdm-seat-configuration-greeter-session
lightdm-seat-configuration-xserver-command
lightdm-seat-configuration-session-wrapper
lightdm-seat-configuration-extra-config
lightdm-gtk-greeter-configuration
lightdm-gtk-greeter-configuration?
lightdm-gtk-greeter-configuration-lightdm-gtk-greeter
lightdm-gtk-greeter-configuration-assets
lightdm-gtk-greeter-configuration-theme-name
lightdm-gtk-greeter-configuration-icon-theme-name
lightdm-gtk-greeter-configuration-cursor-theme-name
lightdm-gtk-greeter-configuration-allow-debug
lightdm-gtk-greeter-configuration-background
lightdm-gtk-greeter-configuration-a11y-states
lightdm-gtk-greeter-configuration-reader
lightdm-gtk-greeter-configuration-extra-config
lightdm-configuration
lightdm-configuration?
lightdm-configuration-lightdm
lightdm-configuration-allow-empty-passwords?
lightdm-configuration-xorg-configuration
lightdm-configuration-greeters
lightdm-configuration-seats
lightdm-configuration-xdmcp?
lightdm-configuration-xdmcp-listen-address
lightdm-configuration-vnc-server?
lightdm-configuration-vnc-server-command
lightdm-configuration-vnc-server-listen-address
lightdm-configuration-vnc-server-port
lightdm-configuration-extra-config
lightdm-service-type))
;;;
;;; Greeters.
;;;
(define list-of-file-likes?
(list-of file-like?))
(define %a11y-states '(contrast font keyboard reader))
(define (a11y-state? value)
(memq value %a11y-states))
(define list-of-a11y-states?
(list-of a11y-state?))
(define-maybe boolean)
(define (serialize-boolean name value)
(define (strip-trailing-? name)
;; field? -> field
(let ((str (symbol->string name)))
(if (string-suffix? "?" str)
(string-drop-right str 1)
str)))
(format #f "~a=~:[false~;true~]~%" (strip-trailing-? name) value))
(define-maybe file-like)
(define (serialize-file-like name value)
#~(format #f "~a=~a~%" '#$name #$value))
(define (serialize-list-of-a11y-states name value)
(format #f "~a=~a~%" name (string-join (map symbol->string value) ";")))
(define (serialize-string name value)
(format #f "~a=~a~%" name value))
(define (serialize-number name value)
(format #f "~a=~a~%" name value))
(define (serialize-list-of-strings _ value)
(string-join value "\n"))
(define-configuration lightdm-gtk-greeter-configuration
(lightdm-gtk-greeter
(file-like lightdm-gtk-greeter)
"The lightdm-gtk-greeter package to use."
empty-serializer)
(assets
(list-of-file-likes (list adwaita-icon-theme
gnome-themes-extra
;; FIXME: hicolor-icon-theme should be in the
;; packages of the desktop templates.
hicolor-icon-theme))
"The list of packages complementing the greeter, such as package providing
icon themes."
empty-serializer)
(theme-name
(string "Adwaita")
"The name of the theme to use.")
(icon-theme-name
(string "Adwaita")
"The name of the icon theme to use.")
(cursor-theme-name
(string "Adwaita")
"The name of the cursor theme to use.")
(cursor-theme-size
(number 16)
"The size to use for the cursor theme.")
(allow-debugging?
maybe-boolean
"Set to #t to enable debug log level.")
(background
(file-like (file-append %artwork-repository
"/backgrounds/guix-checkered-16-9.svg"))
"The background image to use.")
;; FIXME: This should be enabled by default, but it currently doesn't work,
;; failing to connect to D-Bus, causing the login to fail.
(at-spi-enabled?
(boolean #f)
"Enable accessibility support through the Assistive Technology Service
Provider Interface (AT-SPI).")
(a11y-states
(list-of-a11y-states %a11y-states)
"The accessibility features to enable, given as list of symbols.")
(reader
maybe-file-like
"The command to use to launch a screen reader.")
(extra-config
(list-of-strings '())
"Extra configuration values to append to the LightDM GTK Greeter
configuration file."))
(define (strip-record-type-name-brackets name)
"Remove the '<' and '>' brackets from NAME, a symbol."
(let ((name (symbol->string name)))
(if (and (string-prefix? "<" name)
(string-suffix? ">" name))
(string->symbol (string-drop (string-drop-right name 1) 1))
(error "unexpected record type name" name))))
(define (config->name config)
"Return the constructor name (a symbol) from CONFIG."
(strip-record-type-name-brackets
(record-type-name (struct-vtable config))))
(define (greeter-configuration->greeter-fields config)
"Return the fields of CONFIG, a greeter configuration."
(match config
;; Note: register any new greeter configuration here.
((? lightdm-gtk-greeter-configuration?)
lightdm-gtk-greeter-configuration-fields)))
(define (greeter-configuration->packages config)
"Return the list of greeter packages, including assets, used by CONFIG, a
greeter configuration."
(match config
;; Note: register any new greeter configuration here.
((? lightdm-gtk-greeter-configuration?)
(cons (lightdm-gtk-greeter-configuration-lightdm-gtk-greeter config)
(lightdm-gtk-greeter-configuration-assets config)))))
;;; TODO: Implement directly in (gnu services configuration), perhaps by
;;; making the FIELDS argument optional.
(define (serialize-configuration* config)
"Like `serialize-configuration', but not requiring to provide a FIELDS
argument."
(define fields (greeter-configuration->greeter-fields config))
(serialize-configuration config fields))
(define (greeter-configuration->conf-name config)
"Return the file name of CONFIG, a greeter configuration."
(format #f "~a.conf" (greeter-configuration->greeter-session config)))
(define (greeter-configuration->file config)
"Serialize CONFIG into a file under the output directory, so that it can be
easily added to XDG_CONF_DIRS."
(computed-file
(greeter-configuration->conf-name config)
#~(begin
(call-with-output-file #$output
(lambda (port)
(format port (string-append
"[greeter]\n"
#$(serialize-configuration* config))))))))
;;;
;;; Seats.
;;;
(define seat-name? string?)
(define (serialize-seat-name _ value)
(format #f "[Seat:~a]~%" value))
(define (seat-type? type)
(memq type '(local xremote)))
(define (serialize-seat-type name value)
(format #f "~a=~a~%" name value))
(define-maybe seat-type)
(define (greeter-session? value)
(memq value '(lightdm-gtk-greeter)))
(define (serialize-greeter-session name value)
(format #f "~a=~a~%" name value))
(define-maybe greeter-session)
(define-maybe string)
;;; Note: all the fields except for the seat name should be 'maybe's, since
;;; the real default value is set by the %lightdm-seat-default define later,
;;; and this avoids repeating ourselves in the serialized configuration file.
(define-configuration lightdm-seat-configuration
(name
seat-name
"The name of the seat. An asterisk (*) can be used in the name
to apply the seat configuration to all the seat names it matches.")
(user-session
maybe-string
"The session to use by default. The session name must be provided as a
lowercase string, such as @code{\"gnome\"}, @code{\"ratpoison\"}, etc.")
(type
(seat-type 'local)
"The type of the seat, either the @code{local} or @code{xremote} symbol.")
(autologin-user
maybe-string
"The username to automatically log in with by default.")
(greeter-session
(greeter-session 'lightdm-gtk-greeter)
"The greeter session to use, specified as a symbol. Currently, only
@code{lightdm-gtk-greeter} is supported.")
;; Note: xserver-command must be lazily computed, so that it can be
;; overridden via 'lightdm-configuration-xorg-configuration'.
(xserver-command
maybe-file-like
"The Xorg server command to run.")
(session-wrapper
(file-like (xinitrc))
"The xinitrc session wrapper to use.")
(extra-config
(list-of-strings '())
"Extra configuration values to append to the seat configuration section."))
(define (greeter-session->greater-configuration-pred identifier)
"Return the predicate to check if a configuration is of the type specifying
a greeter identified by IDENTIFIER."
(match identifier
;; Note: register any new greeter identifier here.
('lightdm-gtk-greeter
lightdm-gtk-greeter-configuration?)))
(define (greeter-configuration->greeter-session config)
"Given CONFIG, a greeter configuration object, return its identifier,
a symbol."
(let ((suffix "-configuration")
(greeter-conf-name (config->name config)))
(string->symbol (string-drop-right (symbol->string greeter-conf-name)
(string-length suffix)))))
(define list-of-seat-configurations?
(list-of lightdm-seat-configuration?))
;;;
;;; LightDM.
;;;
(define (greeter-configuration? config)
(or (lightdm-gtk-greeter-configuration? config)
;; Note: register any new greeter configuration here.
))
(define (list-of-greeter-configurations? greeter-configs)
(and ((list-of greeter-configuration?) greeter-configs)
;; Greeter configurations must also not be provided more than once.
(let* ((types (map (compose record-type-name struct-vtable)
greeter-configs))
(dupes (filter (lambda (type)
(< 1 (count (cut eq? type <>) types)))
types)))
(unless (null? dupes)
(leave (G_ "duplicate greeter configurations: ~a~%") dupes)))))
(define-configuration/no-serialization lightdm-configuration
(lightdm
(file-like lightdm)
"The lightdm package to use.")
(allow-empty-passwords?
(boolean #f)
"Whether users not having a password set can login.")
(debug?
(boolean #f)
"Enable verbose output.")
(xorg-configuration
(xorg-configuration (xorg-configuration))
"The default Xorg server configuration to use to generate the Xorg server
start script. It can be refined per seat via the @code{xserver-command} of
the @code{<lightdm-seat-configuration>} record, if desired.")
(greeters
(list-of-greeter-configurations (list (lightdm-gtk-greeter-configuration)))
"The LightDM greeter configurations specifying the greeters to use.")
(seats
(list-of-seat-configurations (list (lightdm-seat-configuration
(name "*"))))
"The seat configurations to use. A LightDM seat is akin to a user.")
(xdmcp?
(boolean #f)
"Whether a XDMCP server should listen on port UDP 177.")
(xdmcp-listen-address
maybe-string
"The host or IP address the XDMCP server listens for incoming connections.
When unspecified, listen on for any hosts/IP addresses.")
(vnc-server?
(boolean #f)
"Whether a VNC server is started.")
(vnc-server-command
(file-like (file-append tigervnc-server "/bin/Xvnc"))
"The Xvnc command to use for the VNC server, it's possible to provide extra
options not otherwise exposed along the command, for example to disable
security:
@lisp
(vnc-server-command
(file-append tigervnc-server \"/bin/Xvnc\"
\" -SecurityTypes None\" ))
@end lisp
Or to set a PasswordFile for the classic (unsecure) VncAuth mechanism:
@lisp
(vnc-server-command
(file-append tigervnc-server \"/bin/Xvnc\"
\" -PasswordFile /var/lib/lightdm/.vnc/passwd\"))
@end lisp
The password file should be manually created using the @command{vncpasswd}
command.
Note that LightDM will create new sessions for VNC users, which means they
need to authenticate in the same way as local users would.
")
(vnc-server-listen-address
maybe-string
"The host or IP address the VNC server listens for incoming connections.
When unspecified, listen for any hosts/IP addresses.")
(vnc-server-port
(number 5900)
"The TCP port the VNC server should listen to.")
(extra-config
(list-of-strings '())
"Extra configuration values to append to the LightDM configuration file."))
(define (lightdm-configuration->packages config)
"Return all the greeter packages and their assets defined in CONFIG, a
<lightdm-configuration> object, as well as the lightdm package itself."
(cons (lightdm-configuration-lightdm config)
(append-map greeter-configuration->packages
(lightdm-configuration-greeters config))))
(define (validate-lightdm-configuration config)
"Sanity check CONFIG, a <lightdm-configuration> record instance."
;; This is required to make inter-field validations, such as between the
;; seats and greeters.
(let* ((seats (lightdm-configuration-seats config))
(greeter-sessions (delete-duplicates
(map lightdm-seat-configuration-greeter-session
seats)
eq?))
(greeter-configurations (lightdm-configuration-greeters config))
(missing-greeters
(filter-map
(lambda (id)
(define pred (greeter-session->greater-configuration-pred id))
(if (find pred greeter-configurations)
#f ;happy path
id))
greeter-sessions)))
(unless (null? missing-greeters)
(leave (G_ "no greeter configured for seat greeter sessions: ~a~%")
missing-greeters))))
(define (lightdm-configuration-file config)
(match-record config <lightdm-configuration>
(xorg-configuration seats
xdmcp? xdmcp-listen-address
vnc-server? vnc-server-command vnc-server-listen-address vnc-server-port
extra-config)
(apply
mixed-text-file
"lightdm.conf" "
#
# General configuration
#
[LightDM]
greeter-user=lightdm
sessions-directory=/run/current-system/profile/share/xsessions\
:/run/current-system/profile/share/wayland-sessions
remote-sessions-directory=/run/current-system/profile/share/remote-sessions
"
#~(string-join '#$extra-config "\n")
"
#
# XDMCP Server configuration
#
[XDMCPServer]
enabled=" (if xdmcp? "true" "false") "\n"
(if (maybe-value-set? xdmcp-listen-address)
(format #f "xdmcp-listen-address=~a" xdmcp-listen-address)
"") "
#
# VNC Server configuration
#
[VNCServer]
enabled=" (if vnc-server? "true" "false") "
command=" vnc-server-command "
port=" (number->string vnc-server-port) "\n"
(if (maybe-value-set? vnc-server-listen-address)
(format #f "vnc-server-listen-address=~a" vnc-server-listen-address)
"") "
#
# Seat configuration.
#
"
(map (lambda (seat)
;; This complication exists to propagate a default value for
;; the 'xserver-command' field of the seats. Having a
;; 'xorg-configuration' field at the root of the
;; lightdm-configuration enables the use of
;; 'set-xorg-configuration' and can be more convenient.
(let ((seat* (if (maybe-value-set?
(lightdm-seat-configuration-xserver-command seat))
seat
(lightdm-seat-configuration
(inherit seat)
(xserver-command (xorg-start-command
xorg-configuration))))))
(serialize-configuration seat*
lightdm-seat-configuration-fields)))
seats))))
(define (lightdm-configuration-directory config)
"Return a directory containing the serialized lightdm configuration
and all the serialized greeter configurations from CONFIG."
(file-union "etc-lightdm"
(cons `("lightdm.conf" ,(lightdm-configuration-file config))
(map (lambda (g)
`(,(greeter-configuration->conf-name g)
,(greeter-configuration->file g)))
(lightdm-configuration-greeters config)))))
(define %lightdm-accounts
(list (user-group (name "lightdm") (system? #t))
(user-account
(name "lightdm")
(group "lightdm")
(system? #t)
(comment "LightDM user")
(home-directory "/var/lib/lightdm")
(shell (file-append shadow "/sbin/nologin")))))
(define %lightdm-activation
;; Ensure /var/lib/lightdm is owned by the "lightdm" user. Adapted from the
;; %gdm-activation.
(with-imported-modules '((guix build utils))
#~(begin
(use-modules (guix build utils))
(define (ensure-ownership directory)
(let* ((lightdm (getpwnam "lightdm"))
(uid (passwd:uid lightdm))
(gid (passwd:gid lightdm))
(st (stat directory #f)))
;; Recurse into directory only if it has wrong ownership.
(when (and st
(or (not (= uid (stat:uid st)))
(not (= gid (stat:gid st)))))
(for-each (lambda (file)
(chown file uid gid))
(find-files directory #:directories? #t)))))
(when (not (stat "/var/lib/lightdm-data" #f))
(mkdir-p "/var/lib/lightdm-data"))
(for-each ensure-ownership
'("/var/lib/lightdm"
"/var/lib/lightdm-data")))))
(define (lightdm-pam-service config)
"Return a PAM service for @command{lightdm}."
(unix-pam-service "lightdm"
#:login-uid? #t
#:allow-empty-passwords?
(lightdm-configuration-allow-empty-passwords? config)))
(define (lightdm-greeter-pam-service)
"Return a PAM service for @command{lightdm-greeter}."
(pam-service
(name "lightdm-greeter")
(auth (list
;; Load environment from /etc/environment and ~/.pam_environment.
(pam-entry (control "required") (module "pam_env.so"))
;; Always let the greeter start without authentication.
(pam-entry (control "required") (module "pam_permit.so"))))
;; No action required for account management
(account (list (pam-entry (control "required") (module "pam_permit.so"))))
;; Prohibit changing password.
(password (list (pam-entry (control "required") (module "pam_deny.so"))))
;; Setup session.
(session (list (pam-entry (control "required") (module "pam_unix.so"))))))
(define (lightdm-autologin-pam-service)
"Return a PAM service for @command{lightdm-autologin}}."
(pam-service
(name "lightdm-autologin")
(auth
(list
;; Block login if user is globally disabled.
(pam-entry (control "required") (module "pam_nologin.so"))
(pam-entry (control "required") (module "pam_succeed_if.so")
(arguments (list "uid >= 1000")))
;; Allow access without authentication.
(pam-entry (control "required") (module "pam_permit.so"))))
;; Stop autologin if account requires action.
(account (list (pam-entry (control "required") (module "pam_unix.so"))))
;; Prohibit changing password.
(password (list (pam-entry (control "required") (module "pam_deny.so"))))
;; Setup session.
(session (list (pam-entry (control "required") (module "pam_unix.so"))))))
(define (lightdm-pam-services config)
(list (lightdm-pam-service config)
(lightdm-greeter-pam-service)
(lightdm-autologin-pam-service)))
(define (lightdm-shepherd-service config)
"Return a <lightdm-service> for LightDM using CONFIG."
(validate-lightdm-configuration config)
(define lightdm-command
#~(list #$(file-append (lightdm-configuration-lightdm config)
"/sbin/lightdm")
#$@(if (lightdm-configuration-debug? config)
#~("--debug")
#~())))
(define lightdm-paths
(let ((lightdm (lightdm-configuration-lightdm config)))
#~(string-join
'#$(map (lambda (dir)
(file-append lightdm dir))
'("/bin" "/sbin" "/libexec"))
":")))
(define data-dirs
;; LightDM itself needs to be in XDG_DATA_DIRS for the accountsservice
;; interface it provides to be picked up. The greeters must also be in
;; XDG_DATA_DIRS to be found.
(let ((packages (lightdm-configuration->packages config)))
#~(string-join '#$(map (cut file-append <> "/share") packages)
":")))
(list
(shepherd-service
(documentation "LightDM display manager")
(requirement '(pam dbus-system user-processes host-name))
(provision '(lightdm display-manager xorg-server))
(respawn? #f)
(start
;; Note: sadly, environment variables defined for 'lightdm' are
;; cleared and/or overridden by /etc/profile by its spawned greeters,
;; so an out-of-band means such as /etc is required.
#~(make-forkexec-constructor #$lightdm-command
;; Lightdm needs itself in its PATH.
#:environment-variables
(list
;; It looks for greeter .desktop files as
;; well as lightdm accountsservice
;; interface in XDG_DATA_DIRS.
(string-append "XDG_DATA_DIRS="
#$data-dirs)
(string-append "PATH=" #$lightdm-paths))))
(stop #~(make-kill-destructor)))))
(define (lightdm-etc-service config)
"Return a list of FILES for @var{etc-service-type} to build the
/etc/lightdm directory using CONFIG"
(list `("lightdm" ,(lightdm-configuration-directory config))))
(define lightdm-service-type
(handle-xorg-configuration
lightdm-configuration
(service-type
(name 'lightdm)
(default-value (lightdm-configuration))
(extensions
(list (service-extension pam-root-service-type lightdm-pam-services)
(service-extension shepherd-root-service-type
lightdm-shepherd-service)
(service-extension activation-service-type
(const %lightdm-activation))
(service-extension dbus-root-service-type
(compose list lightdm-configuration-lightdm))
(service-extension polkit-service-type
(compose list lightdm-configuration-lightdm))
(service-extension account-service-type
(const %lightdm-accounts))
;; Add 'lightdm' to the system profile, so that its
;; 'share/accountsservice' D-Bus service extension directory can be
;; found via the 'XDG_DATA_DIRS=/run/current-system/profile/share'
;; environment variable set in the wrapper of the
;; libexec/accounts-daemon binary of the accountsservice package.
;; This daemon is spawned by D-Bus, and there's little we can do to
;; affect its environment. For more reading, see:
;; https://github.com/NixOS/nixpkgs/issues/45059.
(service-extension profile-service-type
lightdm-configuration->packages)
;; This is needed for lightdm and greeter
;; to find their configuration
(service-extension etc-service-type
lightdm-etc-service)))
(description "Run @code{lightdm}, the LightDM graphical login manager."))))
;;;
;;; Generate documentation.
;;;
(define (generate-doc)
(configuration->documentation 'lightdm-configuration)
(configuration->documentation 'lightdm-gtk-greeter-configuration)
(configuration->documentation 'lightdm-seat-configuration))
