174 lines
6.9 KiB
Scheme
174 lines
6.9 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2014, 2015 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu services ssh)
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#:use-module (guix gexp)
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#:use-module (guix store)
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#:use-module (guix monads)
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#:use-module (gnu services)
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#:use-module (gnu system linux) ; 'pam-service'
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#:use-module (gnu packages lsh)
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#:export (lsh-service))
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;;; Commentary:
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;;;
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;;; This module implements secure shell (SSH) services.
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;;;
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;;; Code:
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(define %yarrow-seed
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"/var/spool/lsh/yarrow-seed-file")
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(define (activation lsh host-key)
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"Return the gexp to activate the LSH service for HOST-KEY."
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#~(begin
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(unless (file-exists? #$%yarrow-seed)
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(system* (string-append #$lsh "/bin/lsh-make-seed")
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"--sloppy" "-o" #$%yarrow-seed))
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(unless (file-exists? #$host-key)
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(mkdir-p (dirname #$host-key))
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(format #t "creating SSH host key '~a'...~%" #$host-key)
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;; FIXME: We're just doing a simple pipeline, but 'system' cannot be
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;; used yet because /bin/sh might be dangling; factorize this somehow.
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(let* ((in+out (pipe))
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(keygen (primitive-fork)))
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(case keygen
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((0)
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(close-port (car in+out))
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(close-fdes 1)
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(dup2 (fileno (cdr in+out)) 1)
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(execl (string-append #$lsh "/bin/lsh-keygen")
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"lsh-keygen" "--server"))
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(else
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(let ((write-key (primitive-fork)))
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(case write-key
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((0)
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(close-port (cdr in+out))
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(close-fdes 0)
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(dup2 (fileno (car in+out)) 0)
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(execl (string-append #$lsh "/bin/lsh-writekey")
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"lsh-writekey" "--server" "-o" #$host-key))
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(else
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(close-port (car in+out))
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(close-port (cdr in+out))
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(waitpid keygen)
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(waitpid write-key))))))))))
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(define* (lsh-service #:key
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(lsh lsh)
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(daemonic? #t)
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(host-key "/etc/lsh/host-key")
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(interfaces '())
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(port-number 22)
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(allow-empty-passwords? #f)
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(root-login? #f)
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(syslog-output? #t)
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(pid-file? #f)
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(pid-file "/var/run/lshd.pid")
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(x11-forwarding? #t)
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(tcp/ip-forwarding? #t)
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(password-authentication? #t)
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(public-key-authentication? #t)
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(initialize? #t))
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"Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
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@var{host-key} must designate a file containing the host key, and readable
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only by root.
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When @var{daemonic?} is true, @command{lshd} will detach from the
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controlling terminal and log its output to syslogd, unless one sets
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@var{syslog-output?} to false. Obviously, it also makes lsh-service
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depend on existence of syslogd service. When @var{pid-file?} is true,
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@command{lshd} writes its PID to the file called @var{pid-file}.
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When @var{initialize?} is true, automatically create the seed and host key
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upon service activation if they do not exist yet. This may take long and
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require interaction.
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When @var{initialize?} is false, it is up to the user to initialize the
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randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
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a key pair with the private key stored in file @var{host-key} (@pxref{lshd
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basics,,, lsh, LSH Manual}).
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When @var{interfaces} is empty, lshd listens for connections on all the
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network interfaces; otherwise, @var{interfaces} must be a list of host names
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or addresses.
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@var{allow-empty-passwords?} specifies whether to accept log-ins with empty
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passwords, and @var{root-login?} specifies whether to accept log-ins as
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root.
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The other options should be self-descriptive."
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(define lsh-command
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(append
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(cons #~(string-append #$lsh "/sbin/lshd")
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(if daemonic?
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(let ((syslog (if syslog-output? '()
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(list "--no-syslog"))))
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(cons "--daemonic"
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(if pid-file?
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(cons #~(string-append "--pid-file=" #$pid-file)
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syslog)
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(cons "--no-pid-file" syslog))))
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(if pid-file?
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(list #~(string-append "--pid-file=" #$pid-file))
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'())))
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(cons* #~(string-append "--host-key=" #$host-key)
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#~(string-append "--password-helper=" #$lsh "/sbin/lsh-pam-checkpw")
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#~(string-append "--subsystems=sftp=" #$lsh "/sbin/sftp-server")
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"-p" (number->string port-number)
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(if password-authentication? "--password" "--no-password")
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(if public-key-authentication?
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"--publickey" "--no-publickey")
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(if root-login?
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"--root-login" "--no-root-login")
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(if x11-forwarding?
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"--x11-forward" "--no-x11-forward")
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(if tcp/ip-forwarding?
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"--tcpip-forward" "--no-tcpip-forward")
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(if (null? interfaces)
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'()
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(list (string-append "--interfaces="
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(string-join interfaces ",")))))))
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(define requires
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(if (and daemonic? syslog-output?)
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'(networking syslogd)
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'(networking)))
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(with-monad %store-monad
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(return (service
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(documentation "GNU lsh SSH server")
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(provision '(ssh-daemon))
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(requirement requires)
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(start #~(make-forkexec-constructor (list #$@lsh-command)))
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(stop #~(make-kill-destructor))
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(pam-services
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(list (unix-pam-service
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"lshd"
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#:allow-empty-passwords? allow-empty-passwords?)))
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(activate #~(begin
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(use-modules (guix build utils))
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(mkdir-p "/var/spool/lsh")
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#$(if initialize?
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(activation lsh host-key)
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#t)))))))
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;;; ssh.scm ends here
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