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;;; Guile-Git --- GNU Guile bindings of libgit2
;;; Copyright © 2019 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of Guile-Git.
;;;
;;; Guile-Git 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.
;;;
;;; Guile-Git 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 Guile-Git. If not, see <http://www.gnu.org/licenses/>.
(define-module (tests ssh)
#:use-module (git auth)
#:use-module (tests helpers)
#:use-module ((srfi srfi-64) #:select (test-skip))
#:use-module (ice-9 popen)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 regex)
#:export (sshd-available?
with-sshd-server
with-ssh-agent
make-client-ssh-auth))
(define sshd "@SSHD@")
(define %ssh-dir (path-join "@abs_top_builddir@" "/tests/.ssh"))
(define (in-ssh-directory . args)
(apply path-join %ssh-dir args))
(define (sshd-available?)
;; Return #t if sshd is available (it does not support
;; ‘--version’ or anything similar though).
(= 256 (parameterize ((current-error-port (%make-void-port "w")))
(system* sshd "--something-not-supported"))))
(define (start-sshd port)
(define (write-authorized-keys file)
(call-with-output-file file
(lambda (port)
;; We need to pass PATH so that git binary (git-upload-pack) can be
;; found from sshd.
(format port "environment=\"PATH=~a\" ~a"
(getenv "PATH")
(call-with-input-file (in-ssh-directory "id_rsa_client.pub")
read-string)))))
(define (write-sshd-conf conf authorized-keys)
(call-with-output-file conf
(lambda (port)
(format port "\
# Listen only on the loopback device.
ListenAddress localhost
AuthorizedKeysFile ~a
PidFile ~a
PermitUserEnvironment yes
# libssh2 and therefore libgit2 do not yet support
# sha2-based rsa algorithms.
# See upstream issue:
# https://github.com/libssh2/libssh2/issues/536
HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa
# Disable permission checks on auth files for the sake
# of isolated build environments.
StrictModes no~%"
authorized-keys
(in-ssh-directory "sshd_pid")))))
(let ((sshd-conf (in-ssh-directory "sshd.conf"))
(sshd-key (in-ssh-directory "id_rsa_server"))
(authorized-keys (in-ssh-directory "authorized_keys")))
(unsetenv "SSH_AUTH_SOCK")
(chmod sshd-key #o600)
(write-authorized-keys authorized-keys)
(write-sshd-conf sshd-conf authorized-keys)
(system* sshd "-p" (number->string port) "-f" sshd-conf "-h" sshd-key)))
(define (stop-sshd)
(define (read-pid port)
(string-trim-right (read-string port) #\newline))
(let ((pid
(call-with-input-file (in-ssh-directory "sshd_pid")
read-pid)))
(system* "kill" pid)))
(define (valid-user-shell?)
"Return true if the current user has a valid shell in /etc/passwd."
;; Note: This check is useful to account for Guix build environments, where
;; /etc/passwd refers to a non-existent shell for the build user. In that
;; case, it's impossible to log in over SSH as sshd blindly attempts to
;; execute the user shell.
(and=> (false-if-exception (getpwuid (getuid)))
(lambda (passwd)
(let ((shell (passwd:shell passwd)))
(access? shell (logior R_OK X_OK))))))
(define-syntax-rule (with-sshd-server port tests ...)
(let ((skip? (or (not (sshd-available?))
(not (valid-user-shell?)))))
(dynamic-wind
(lambda ()
(if skip?
(test-skip (length '(tests ...)))
(start-sshd port)))
(lambda ()
tests ...)
(lambda ()
(unless skip?
(stop-sshd))))))
(define %ssh-auth-sock-regexp
(make-regexp "SSH_AUTH_SOCK=(.*); export SSH_AUTH_SOCK;"))
(define %ssh-agent-pid-regexp
(make-regexp "SSH_AGENT_PID=(.*); export SSH_AGENT_PID;"))
(define (start-ssh-agent)
(let* ((p (open-input-pipe "ssh-agent -s"))
(ssh-auth-sock-data (read-line p))
(ssh-agent-pid-data (read-line p))
(sock
(let ((match (regexp-exec %ssh-auth-sock-regexp
ssh-auth-sock-data)))
(match:substring match 1)))
(pid (let ((match (regexp-exec %ssh-agent-pid-regexp
ssh-agent-pid-data)))
(match:substring match 1))))
(setenv "SSH_AUTH_SOCK" sock)
pid))
(define (ssh-agent-add-client-key)
(system* "ssh-add" (in-ssh-directory "id_rsa_client")))
(define-syntax-rule (with-ssh-agent body ...)
(let ((pid (start-ssh-agent)))
(dynamic-wind
(const #f)
(lambda ()
(ssh-agent-add-client-key)
body ...)
(lambda ()
(system* "kill" pid)
(unsetenv "SSH_AUTH_SOCK")))))
(define (make-client-ssh-auth)
(let ((pub-key (in-ssh-directory "id_rsa_client.pub"))
(pri-key (in-ssh-directory "id_rsa_client")))
(chmod pri-key #o600)
(chmod pub-key #o644)
(%make-auth-ssh-credentials
pub-key
pri-key)))
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