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guix/gnu/services/ssh.scm
Martin Castillo 985934cb21
services: openssh: Add 'accepted-environment' field. 
* gnu/services/ssh.scm (<openssh-configuration>)[accepted-environment]: New field.
(openssh-config-file): Honor 'acccepted-environment'.
* doc/guix.texi (Networking Services): Document it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>
2018-03-18 00:02:05 +01:00

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 David Craven <david@craven.ch>
;;; Copyright © 2016 Julien Lepiller <julien@lepiller.eu>
;;; Copyright © 2017 Clément Lassieur <clement@lassieur.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 (gnu packages ssh)
#:use-module (gnu packages admin)
#:use-module (gnu services)
#:use-module (gnu services shepherd)
#:use-module (gnu system pam)
#:use-module (gnu system shadow)
#:use-module (guix gexp)
#:use-module (guix records)
#:use-module (guix modules)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:export (lsh-configuration
lsh-configuration?
lsh-service
lsh-service-type
openssh-configuration
openssh-configuration?
openssh-service-type
dropbear-configuration
dropbear-configuration?
dropbear-service-type
dropbear-service))
;;; Commentary:
;;;
;;; This module implements secure shell (SSH) services.
;;;
;;; Code:
(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-shepherd-service config)
"Return a <shepherd-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 (file-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=" #$lsh "/sbin/sftp-server")
"-p" (number->string (lsh-configuration-port-number config))
(if (lsh-configuration-password-authentication? config)
"--password" "--no-password")
(if (lsh-configuration-public-key-authentication? config)
"--publickey" "--no-publickey")
(if (lsh-configuration-root-login? config)
"--root-login" "--no-root-login")
(if (lsh-configuration-x11-forwarding? config)
"--x11-forward" "--no-x11-forward")
(if (lsh-configuration-tcp/ip-forwarding? config)
"--tcpip-forward" "--no-tcpip-forward")
(if (null? interfaces)
'()
(map (cut string-append "--interface=" <>)
interfaces)))))
(define requires
(if (and daemonic? (lsh-configuration-syslog-output? config))
'(networking syslogd)
'(networking)))
(list (shepherd-service
(documentation "GNU lsh SSH server")
(provision '(ssh-daemon))
(requirement requires)
(start #~(make-forkexec-constructor (list #$@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)
(description
"Run the GNU@tie{}lsh secure shell (SSH) daemon,
@command{lshd}.")
(extensions
(list (service-extension shepherd-root-service-type
lsh-shepherd-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?))))
;;;
;;; OpenSSH.
;;;
(define-record-type* <openssh-configuration>
openssh-configuration make-openssh-configuration
openssh-configuration?
;; <package>
(openssh openssh-configuration-openssh
(default openssh))
;; string
(pid-file openssh-configuration-pid-file
(default "/var/run/sshd.pid"))
;; integer
(port-number openssh-configuration-port-number
(default 22))
;; Boolean | 'without-password
(permit-root-login openssh-configuration-permit-root-login
(default #f))
;; Boolean
(allow-empty-passwords? openssh-configuration-allow-empty-passwords?
(default #f))
;; Boolean
(password-authentication? openssh-configuration-password-authentication?
(default #t))
;; Boolean
(public-key-authentication? openssh-configuration-public-key-authentication?
(default #t))
;; Boolean
(x11-forwarding? openssh-configuration-x11-forwarding?
(default #f))
;; Boolean
(challenge-response-authentication? openssh-challenge-response-authentication?
(default #f))
;; Boolean
(use-pam? openssh-configuration-use-pam?
(default #t))
;; Boolean
(print-last-log? openssh-configuration-print-last-log?
(default #t))
;; list of two-element lists
(subsystems openssh-configuration-subsystems
(default '(("sftp" "internal-sftp"))))
;; list of strings
(accepted-environment openssh-configuration-accepted-environment
(default '()))
;; list of user-name/file-like tuples
(authorized-keys openssh-authorized-keys
(default '()))
;; Boolean
;; XXX: This should really be handled in an orthogonal way, for instance as
;; proposed in <https://bugs.gnu.org/27155>. Keep it internal/undocumented
;; for now.
(%auto-start? openssh-auto-start?
(default #t)))
(define %openssh-accounts
(list (user-group (name "sshd") (system? #t))
(user-account
(name "sshd")
(group "sshd")
(system? #t)
(comment "sshd privilege separation user")
(home-directory "/var/run/sshd")
(shell #~(string-append #$shadow "/sbin/nologin")))))
(define (openssh-activation config)
"Return the activation GEXP for CONFIG."
(with-imported-modules '((guix build utils))
#~(begin
(use-modules (guix build utils))
(define (touch file-name)
(call-with-output-file file-name (const #t)))
;; Make sure /etc/ssh can be read by the 'sshd' user.
(mkdir-p "/etc/ssh")
(chmod "/etc/ssh" #o755)
(mkdir-p (dirname #$(openssh-configuration-pid-file config)))
;; 'sshd' complains if the authorized-key directory and its parents
;; are group-writable, which rules out /gnu/store. Thus we copy the
;; authorized-key directory to /etc.
(catch 'system-error
(lambda ()
(delete-file-recursively "/etc/authorized_keys.d"))
(lambda args
(unless (= ENOENT (system-error-errno args))
(apply throw args))))
(copy-recursively #$(authorized-key-directory
(openssh-authorized-keys config))
"/etc/ssh/authorized_keys.d")
(chmod "/etc/ssh/authorized_keys.d" #o555)
(let ((lastlog "/var/log/lastlog"))
(when #$(openssh-configuration-print-last-log? config)
(unless (file-exists? lastlog)
(touch lastlog))))
;; Generate missing host keys.
(system* (string-append #$(openssh-configuration-openssh config)
"/bin/ssh-keygen") "-A"))))
(define (authorized-key-directory keys)
"Return a directory containing the authorized keys specified in KEYS, a list
of user-name/file-like tuples."
(define build
(with-imported-modules (source-module-closure '((guix build utils)))
#~(begin
(use-modules (ice-9 match) (srfi srfi-26)
(guix build utils))
(mkdir #$output)
(for-each (match-lambda
((user keys ...)
(let ((file (string-append #$output "/" user)))
(call-with-output-file file
(lambda (port)
(for-each (lambda (key)
(call-with-input-file key
(cut dump-port <> port)))
keys))))))
'#$keys))))
(computed-file "openssh-authorized-keys" build))
(define (openssh-config-file config)
"Return the sshd configuration file corresponding to CONFIG."
(computed-file
"sshd_config"
#~(begin
(use-modules (ice-9 match))
(call-with-output-file #$output
(lambda (port)
(display "# Generated by 'openssh-service'.\n" port)
(format port "Port ~a\n"
#$(number->string
(openssh-configuration-port-number config)))
(format port "PermitRootLogin ~a\n"
#$(match (openssh-configuration-permit-root-login config)
(#t "yes")
(#f "no")
('without-password "without-password")))
(format port "PermitEmptyPasswords ~a\n"
#$(if (openssh-configuration-allow-empty-passwords? config)
"yes" "no"))
(format port "PasswordAuthentication ~a\n"
#$(if (openssh-configuration-password-authentication? config)
"yes" "no"))
(format port "PubkeyAuthentication ~a\n"
#$(if (openssh-configuration-public-key-authentication?
config)
"yes" "no"))
(format port "X11Forwarding ~a\n"
#$(if (openssh-configuration-x11-forwarding? config)
"yes" "no"))
(format port "PidFile ~a\n"
#$(openssh-configuration-pid-file config))
(format port "ChallengeResponseAuthentication ~a\n"
#$(if (openssh-challenge-response-authentication? config)
"yes" "no"))
(format port "UsePAM ~a\n"
#$(if (openssh-configuration-use-pam? config)
"yes" "no"))
(format port "PrintLastLog ~a\n"
#$(if (openssh-configuration-print-last-log? config)
"yes" "no"))
;; Add '/etc/authorized_keys.d/%u', which we populate.
(format port "AuthorizedKeysFile \
.ssh/authorized_keys .ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u\n")
(for-each (lambda (s) (format port "AcceptEnv ~a\n" s))
'#$(openssh-configuration-accepted-environment config))
(for-each
(match-lambda
((name command) (format port "Subsystem\t~a\t~a\n" name command)))
'#$(openssh-configuration-subsystems config))
#t)))))
(define (openssh-shepherd-service config)
"Return a <shepherd-service> for openssh with CONFIG."
(define pid-file
(openssh-configuration-pid-file config))
(define openssh-command
#~(list (string-append #$(openssh-configuration-openssh config) "/sbin/sshd")
"-D" "-f" #$(openssh-config-file config)))
(list (shepherd-service
(documentation "OpenSSH server.")
(requirement '(syslogd))
(provision '(ssh-daemon))
(start #~(make-forkexec-constructor #$openssh-command
#:pid-file #$pid-file))
(stop #~(make-kill-destructor))
(auto-start? (openssh-auto-start? config)))))
(define (openssh-pam-services config)
"Return a list of <pam-services> for sshd with CONFIG."
(list (unix-pam-service
"sshd"
#:allow-empty-passwords?
(openssh-configuration-allow-empty-passwords? config))))
(define (extend-openssh-authorized-keys config keys)
"Extend CONFIG with the extra authorized keys listed in KEYS."
(openssh-configuration
(inherit config)
(authorized-keys
(append (openssh-authorized-keys config) keys))))
(define openssh-service-type
(service-type (name 'openssh)
(description
"Run the OpenSSH secure shell (SSH) server, @command{sshd}.")
(extensions
(list (service-extension shepherd-root-service-type
openssh-shepherd-service)
(service-extension pam-root-service-type
openssh-pam-services)
(service-extension activation-service-type
openssh-activation)
(service-extension account-service-type
(const %openssh-accounts))))
(compose concatenate)
(extend extend-openssh-authorized-keys)
(default-value (openssh-configuration))))
;;;
;;; Dropbear.
;;;
(define-record-type* <dropbear-configuration>
dropbear-configuration make-dropbear-configuration
dropbear-configuration?
(dropbear dropbear-configuration-dropbear
(default dropbear))
(port-number dropbear-configuration-port-number
(default 22))
(syslog-output? dropbear-configuration-syslog-output?
(default #t))
(pid-file dropbear-configuration-pid-file
(default "/var/run/dropbear.pid"))
(root-login? dropbear-configuration-root-login?
(default #f))
(allow-empty-passwords? dropbear-configuration-allow-empty-passwords?
(default #f))
(password-authentication? dropbear-configuration-password-authentication?
(default #t)))
(define (dropbear-activation config)
"Return the activation gexp for CONFIG."
#~(begin
(use-modules (guix build utils))
(mkdir-p "/etc/dropbear")))
(define (dropbear-shepherd-service config)
"Return a <shepherd-service> for dropbear with CONFIG."
(define dropbear
(dropbear-configuration-dropbear config))
(define pid-file
(dropbear-configuration-pid-file config))
(define dropbear-command
#~(list (string-append #$dropbear "/sbin/dropbear")
;; '-R' allows host keys to be automatically generated upon first
;; connection, at a time when /dev/urandom is more likely securely
;; seeded.
"-F" "-R"
"-p" #$(number->string (dropbear-configuration-port-number config))
"-P" #$pid-file
#$@(if (dropbear-configuration-syslog-output? config) '() '("-E"))
#$@(if (dropbear-configuration-root-login? config) '() '("-w"))
#$@(if (dropbear-configuration-password-authentication? config)
'()
'("-s" "-g"))
#$@(if (dropbear-configuration-allow-empty-passwords? config)
'("-B")
'())))
(define requires
(if (dropbear-configuration-syslog-output? config)
'(networking syslogd) '(networking)))
(list (shepherd-service
(documentation "Dropbear SSH server.")
(requirement requires)
(provision '(ssh-daemon))
(start #~(make-forkexec-constructor #$dropbear-command
#:pid-file #$pid-file))
(stop #~(make-kill-destructor)))))
(define dropbear-service-type
(service-type (name 'dropbear)
(description
"Run the Dropbear secure shell (SSH) server.")
(extensions
(list (service-extension shepherd-root-service-type
dropbear-shepherd-service)
(service-extension activation-service-type
dropbear-activation)))))
(define* (dropbear-service #:optional (config (dropbear-configuration)))
"Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
daemon} with the given @var{config}, a @code{<dropbear-configuration>}
object."
(service dropbear-service-type config))
;;; ssh.scm ends here
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