guix-devel/gnu/services/ssh.scm

619 lines
25 KiB
Scheme
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017, 2018 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
(allow-agent-forwarding? openssh-configuration-allow-agent-forwarding?
(default #t))
;; Boolean
(allow-tcp-forwarding? openssh-configuration-allow-tcp-forwarding?
(default #t))
;; Boolean
(gateway-ports? openssh-configuration-gateway-ports?
(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 '()))
;; symbol
(log-level openssh-configuration-log-level
(default 'info))
;; 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"
#$(if (openssh-configuration-x11-forwarding? config)
"yes" "no"))
(format port "AllowAgentForwarding ~a\n"
#$(if (openssh-configuration-allow-agent-forwarding? config)
"yes" "no"))
(format port "AllowTcpForwarding ~a\n"
#$(if (openssh-configuration-allow-tcp-forwarding? config)
"yes" "no"))
(format port "GatewayPorts ~a\n"
#$(if (openssh-configuration-gateway-ports? 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"))
(format port "LogLevel ~a\n"
#$(string-upcase
(symbol->string
(openssh-configuration-log-level config))))
;; Add '/etc/authorized_keys.d/%u', which we populate.
(format port "AuthorizedKeysFile \
.ssh/authorized_keys .ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u\n")
(for-each (lambda (s) (format port "AcceptEnv ~a\n" s))
'#$(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" #$(openssh-config-file config)))
(list (shepherd-service
(documentation "OpenSSH server.")
(requirement '(syslogd loopback))
(provision '(ssh-daemon))
(start #~(make-forkexec-constructor #$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))
;; Install OpenSSH in the system profile. That way,
;; 'scp' is found when someone tries to copy to or from
;; this machine.
(service-extension profile-service-type
(lambda (config)
(list (openssh-configuration-openssh
config))))))
(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