;;; 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 store) #:use-module (guix monads) #:use-module (gnu services) #:use-module (gnu system linux) ; 'pam-service' #:use-module (gnu packages lsh) #:export (lsh-service)) ;;; Commentary: ;;; ;;; This module implements secure shell (SSH) services. ;;; ;;; Code: (define %yarrow-seed "/var/spool/lsh/yarrow-seed-file") (define (activation lsh host-key) "Return the gexp to activate 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" #$host-key)) (else (close-port (car in+out)) (close-port (cdr in+out)) (waitpid keygen) (waitpid write-key)))))))))) (define* (lsh-service #:key (lsh lsh) (daemonic? #t) (host-key "/etc/lsh/host-key") (interfaces '()) (port-number 22) (allow-empty-passwords? #f) (root-login? #f) (syslog-output? #t) (pid-file? #f) (pid-file "/var/run/lshd.pid") (x11-forwarding? #t) (tcp/ip-forwarding? #t) (password-authentication? #t) (public-key-authentication? #t) (initialize? #t)) "Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}. @var{host-key} must designate a file containing the host key, and readable only by root. When @var{daemonic?} is true, @command{lshd} will detach from the controlling terminal and log its output to syslogd, unless one sets @var{syslog-output?} to false. Obviously, it also makes lsh-service depend on existence of syslogd service. When @var{pid-file?} is true, @command{lshd} writes its PID to the file called @var{pid-file}. When @var{initialize?} is true, automatically create the seed and host key upon service activation if they do not exist yet. This may take long and require interaction. When @var{initialize?} is false, it is up to the user to initialize the randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create a key pair with the private key stored in file @var{host-key} (@pxref{lshd basics,,, lsh, LSH Manual}). When @var{interfaces} is empty, lshd listens for connections on all the network interfaces; otherwise, @var{interfaces} must be a list of host names or addresses. @var{allow-empty-passwords?} specifies whether to accept log-ins with empty passwords, and @var{root-login?} specifies whether to accept log-ins as root. The other options should be self-descriptive." (define lsh-command (append (cons #~(string-append #$lsh "/sbin/lshd") (if daemonic? (let ((syslog (if syslog-output? '() (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=" #$host-key) #~(string-append "--password-helper=" #$lsh "/sbin/lsh-pam-checkpw") #~(string-append "--subsystems=sftp=" #$lsh "/sbin/sftp-server") "-p" (number->string port-number) (if password-authentication? "--password" "--no-password") (if public-key-authentication? "--publickey" "--no-publickey") (if root-login? "--root-login" "--no-root-login") (if x11-forwarding? "--x11-forward" "--no-x11-forward") (if tcp/ip-forwarding? "--tcpip-forward" "--no-tcpip-forward") (if (null? interfaces) '() (list (string-append "--interfaces=" (string-join interfaces ","))))))) (define requires (if (and daemonic? syslog-output?) '(networking syslogd) '(networking))) (with-monad %store-monad (return (service (documentation "GNU lsh SSH server") (provision '(ssh-daemon)) (requirement requires) (start #~(make-forkexec-constructor (list #$@lsh-command))) (stop #~(make-kill-destructor)) (pam-services (list (unix-pam-service "lshd" #:allow-empty-passwords? allow-empty-passwords?))) (activate #~(begin (use-modules (guix build utils)) (mkdir-p "/var/spool/lsh") #$(if initialize? (activation lsh host-key) #t))))))) ;;; ssh.scm ends here