;;; 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) (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 user-name/file-like tuples (authorized-keys openssh-authorized-keys (default '()))) (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" #$(if (openssh-configuration-print-last-log? config) "yes" "no")) ;; Add '/etc/authorized_keys.d/%u', which we populate. (format port "AuthorizedKeysFile \ .ssh/authorized_keys .ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u\n") (for-each (match-lambda ((name command) (format port "Subsystem\t~a\t~a\n" name command))) '#$(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))))) (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) (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) (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