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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 ssh)
#:use-module (guix gexp)
#:use-module (guix records)
#:use-module (gnu services)
#:use-module (gnu services dmd)
#:use-module (gnu system linux) ; 'pam-service'
#:use-module (gnu packages lsh)
#:export (lsh-service))
;;; Commentary:
;;;
;;; This module implements secure shell (SSH) services.
;;;
;;; Code:
;; TODO: Export.
(define-record-type* <lsh-configuration>
lsh-configuration make-lsh-configuration
lsh-configuration?
(lsh lsh-configuration-lsh
(default lsh))
(daemonic? lsh-configuration-daemonic?)
(host-key lsh-configuration-host-key)
(interfaces lsh-configuration-interfaces)
(port-number lsh-configuration-port-number)
(allow-empty-passwords? lsh-configuration-allow-empty-passwords?)
(root-login? lsh-configuration-root-login?)
(syslog-output? lsh-configuration-syslog-output?)
(pid-file? lsh-configuration-pid-file?)
(pid-file lsh-configuration-pid-file)
(x11-forwarding? lsh-configuration-x11-forwarding?)
(tcp/ip-forwarding? lsh-configuration-tcp/ip-forwarding?)
(password-authentication? lsh-configuration-password-authentication?)
(public-key-authentication? lsh-configuration-public-key-authentication?)
(initialize? lsh-configuration-initialize?))
(define %yarrow-seed
"/var/spool/lsh/yarrow-seed-file")
(define (lsh-initialization lsh host-key)
"Return the gexp to initialize the LSH service for HOST-KEY."
#~(begin
(unless (file-exists? #$%yarrow-seed)
(system* (string-append #$lsh "/bin/lsh-make-seed")
"--sloppy" "-o" #$%yarrow-seed))
(unless (file-exists? #$host-key)
(mkdir-p (dirname #$host-key))
(format #t "creating SSH host key '~a'...~%" #$host-key)
;; FIXME: We're just doing a simple pipeline, but 'system' cannot be
;; used yet because /bin/sh might be dangling; factorize this somehow.
(let* ((in+out (pipe))
(keygen (primitive-fork)))
(case keygen
((0)
(close-port (car in+out))
(close-fdes 1)
(dup2 (fileno (cdr in+out)) 1)
(execl (string-append #$lsh "/bin/lsh-keygen")
"lsh-keygen" "--server"))
(else
(let ((write-key (primitive-fork)))
(case write-key
((0)
(close-port (cdr in+out))
(close-fdes 0)
(dup2 (fileno (car in+out)) 0)
(execl (string-append #$lsh "/bin/lsh-writekey")
"lsh-writekey" "--server" "-o" #$host-key))
(else
(close-port (car in+out))
(close-port (cdr in+out))
(waitpid keygen)
(waitpid write-key))))))))))
(define (lsh-activation config)
"Return the activation gexp for CONFIG."
#~(begin
(use-modules (guix build utils))
(mkdir-p "/var/spool/lsh")
#$(if (lsh-configuration-initialize? config)
(lsh-initialization (lsh-configuration-lsh config)
(lsh-configuration-host-key config))
#t)))
(define (lsh-dmd-service config)
"Return a <dmd-service> for lsh with CONFIG."
(define lsh (lsh-configuration-lsh config))
(define pid-file (lsh-configuration-pid-file config))
(define pid-file? (lsh-configuration-pid-file? config))
(define daemonic? (lsh-configuration-daemonic? config))
(define interfaces (lsh-configuration-interfaces config))
(define lsh-command
(append
(cons #~(string-append #$lsh "/sbin/lshd")
(if daemonic?
(let ((syslog (if (lsh-configuration-syslog-output? config)
'()
(list "--no-syslog"))))
(cons "--daemonic"
(if pid-file?
(cons #~(string-append "--pid-file=" #$pid-file)
syslog)
(cons "--no-pid-file" syslog))))
(if pid-file?
(list #~(string-append "--pid-file=" #$pid-file))
'())))
(cons* #~(string-append "--host-key="
#$(lsh-configuration-host-key config))
#~(string-append "--password-helper=" #$lsh "/sbin/lsh-pam-checkpw")
#~(string-append "--subsystems=sftp=" #$lsh "/sbin/sftp-server")
"-p" (number->string (lsh-configuration-port-number config))
(if (lsh-configuration-password-authentication? config)
"--password" "--no-password")
(if (lsh-configuration-public-key-authentication? config)
"--publickey" "--no-publickey")
(if (lsh-configuration-root-login? config)
"--root-login" "--no-root-login")
(if (lsh-configuration-x11-forwarding? config)
"--x11-forward" "--no-x11-forward")
(if (lsh-configuration-tcp/ip-forwarding? config)
"--tcpip-forward" "--no-tcpip-forward")
(if (null? interfaces)
'()
(list (string-append "--interfaces="
(string-join interfaces ",")))))))
(define requires
(if (and daemonic? (lsh-configuration-syslog-output? config))
'(networking syslogd)
'(networking)))
(list (dmd-service
(documentation "GNU lsh SSH server")
(provision '(ssh-daemon))
(requirement requires)
(start #~(make-forkexec-constructor (list #$@lsh-command)))
(stop #~(make-kill-destructor)))))
(define (lsh-pam-services config)
"Return a list of <pam-services> for lshd with CONFIG."
(list (unix-pam-service
"lshd"
#:allow-empty-passwords?
(lsh-configuration-allow-empty-passwords? config))))
(define lsh-service-type
(service-type (name 'lsh)
(extensions
(list (service-extension dmd-root-service-type
lsh-dmd-service)
(service-extension pam-root-service-type
lsh-pam-services)
(service-extension activation-service-type
lsh-activation)))))
(define* (lsh-service #:key
(lsh lsh)
(daemonic? #t)
(host-key "/etc/lsh/host-key")
(interfaces '())
(port-number 22)
(allow-empty-passwords? #f)
(root-login? #f)
(syslog-output? #t)
(pid-file? #f)
(pid-file "/var/run/lshd.pid")
(x11-forwarding? #t)
(tcp/ip-forwarding? #t)
(password-authentication? #t)
(public-key-authentication? #t)
(initialize? #t))
"Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
@var{host-key} must designate a file containing the host key, and readable
only by root.
When @var{daemonic?} is true, @command{lshd} will detach from the
controlling terminal and log its output to syslogd, unless one sets
@var{syslog-output?} to false. Obviously, it also makes lsh-service
depend on existence of syslogd service. When @var{pid-file?} is true,
@command{lshd} writes its PID to the file called @var{pid-file}.
When @var{initialize?} is true, automatically create the seed and host key
upon service activation if they do not exist yet. This may take long and
require interaction.
When @var{initialize?} is false, it is up to the user to initialize the
randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
a key pair with the private key stored in file @var{host-key} (@pxref{lshd
basics,,, lsh, LSH Manual}).
When @var{interfaces} is empty, lshd listens for connections on all the
network interfaces; otherwise, @var{interfaces} must be a list of host names
or addresses.
@var{allow-empty-passwords?} specifies whether to accept log-ins with empty
passwords, and @var{root-login?} specifies whether to accept log-ins as
root.
The other options should be self-descriptive."
(service lsh-service-type
(lsh-configuration (lsh lsh) (daemonic? daemonic?)
(host-key host-key) (interfaces interfaces)
(port-number port-number)
(allow-empty-passwords? allow-empty-passwords?)
(root-login? root-login?)
(syslog-output? syslog-output?)
(pid-file? pid-file?) (pid-file pid-file)
(x11-forwarding? x11-forwarding?)
(tcp/ip-forwarding? tcp/ip-forwarding?)
(password-authentication?
password-authentication?)
(public-key-authentication?
public-key-authentication?)
(initialize? initialize?))))
;;; ssh.scm ends here
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