From patchwork Tue Dec 3 21:15:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Ludovic_Court=C3=A8s?= X-Patchwork-Id: 16364 Return-Path: X-Original-To: patchwork@mira.cbaines.net Delivered-To: patchwork@mira.cbaines.net Received: by mira.cbaines.net (Postfix, from userid 113) id 1E7B817835; Tue, 3 Dec 2019 21:46:31 +0000 (GMT) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mira.cbaines.net X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mira.cbaines.net (Postfix) with ESMTP id D6A6E1782E for ; Tue, 3 Dec 2019 21:46:30 +0000 (GMT) Received: from localhost ([::1]:59174 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icG05-0004yQ-6F for patchwork@mira.cbaines.net; Tue, 03 Dec 2019 16:46:29 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39687) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icFXd-0000km-KT for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1icFXb-0002fi-2A for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:04 -0500 Received: from debbugs.gnu.org ([209.51.188.43]:35170) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1icFXa-0002ez-PS for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:02 -0500 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1icFXa-00075c-L8 for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:02 -0500 X-Loop: help-debbugs@gnu.org Subject: [bug#38478] [PATCH 3/4] ssh: 'open-ssh-session' can be passed the expected host key. Resent-From: Ludovic =?utf-8?q?Court=C3=A8s?= Original-Sender: "Debbugs-submit" Resent-CC: guix-patches@gnu.org Resent-Date: Tue, 03 Dec 2019 21:17:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 38478 X-GNU-PR-Package: guix-patches X-GNU-PR-Keywords: patch To: 38478@debbugs.gnu.org Cc: Ludovic =?utf-8?q?Court=C3=A8s?= Received: via spool by 38478-submit@debbugs.gnu.org id=B38478.157540778627180 (code B ref 38478); Tue, 03 Dec 2019 21:17:02 +0000 Received: (at 38478) by debbugs.gnu.org; 3 Dec 2019 21:16:26 +0000 Received: from localhost ([127.0.0.1]:41138 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1icFX0-00074E-AX for submit@debbugs.gnu.org; Tue, 03 Dec 2019 16:16:26 -0500 Received: from eggs.gnu.org ([209.51.188.92]:57911) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1icFWy-00073o-Ga for 38478@debbugs.gnu.org; Tue, 03 Dec 2019 16:16:25 -0500 Received: from fencepost.gnu.org ([2001:470:142:3::e]:36207) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1icFWq-0001Or-6K; Tue, 03 Dec 2019 16:16:19 -0500 Received: from [102.78.164.116] (port=18308 helo=gnu.org) by fencepost.gnu.org with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1icFWo-0001Km-B1; Tue, 03 Dec 2019 16:16:15 -0500 From: Ludovic =?utf-8?q?Court=C3=A8s?= Date: Tue, 3 Dec 2019 22:15:56 +0100 Message-Id: <20191203211557.21145-3-ludo@gnu.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203211557.21145-1-ludo@gnu.org> References: <20191203211557.21145-1-ludo@gnu.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.51.188.43 X-BeenThere: guix-patches@gnu.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+patchwork=mira.cbaines.net@gnu.org Sender: "Guix-patches" X-getmail-retrieved-from-mailbox: Patches * guix/ssh.scm (open-ssh-session): Add #:host-key parameter. Pass #:knownhosts to 'make-session'. When HOST-KEY is true, call 'authenticate-server*' instead of 'authenticate-server'. --- guix/ssh.scm | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/guix/ssh.scm b/guix/ssh.scm index 519c723155..291ce20b61 100644 --- a/guix/ssh.scm +++ b/guix/ssh.scm @@ -98,14 +98,20 @@ actual key does not match." key type)))))))) (define* (open-ssh-session host #:key user port identity + host-key (compression %compression) (timeout 3600)) "Open an SSH session for HOST and return it. IDENTITY specifies the file name of a private key to use for authenticating with the host. When USER, PORT, or IDENTITY are #f, use default values or whatever '~/.ssh/config' -specifies; otherwise use them. Install TIMEOUT as the maximum time in seconds -after which a read or write operation on a channel of the returned session is -considered as failing. +specifies; otherwise use them. + +When HOST-KEY is true, it must be a string like \"ssh-ed25519 AAAAC3Nz… +root@example.org\"; the server is authenticated and an error is raised if its +host key is different from HOST-KEY. + +Install TIMEOUT as the maximum time in seconds after which a read or write +operation on a channel of the returned session is considered as failing. Throw an error on failure." (let ((session (make-session #:user user @@ -115,6 +121,11 @@ Throw an error on failure." #:timeout 10 ;seconds ;; #:log-verbosity 'protocol + ;; Prevent libssh from reading + ;; ~/.ssh/known_hosts when the caller provides + ;; a HOST-KEY to match against. + #:knownhosts (and host-key "/dev/null") + ;; We need lightweight compression when ;; exchanging full archives. #:compression compression @@ -125,16 +136,20 @@ Throw an error on failure." (match (connect! session) ('ok - ;; Authenticate against ~/.ssh/known_hosts. - (match (authenticate-server session) - ('ok #f) - (reason - (raise (condition - (&message - (message (format #f (G_ "failed to authenticate \ + (if host-key + ;; Make sure the server's key is what we expect. + (authenticate-server* session host-key) + + ;; Authenticate against ~/.ssh/known_hosts. + (match (authenticate-server session) + ('ok #f) + (reason + (raise (condition + (&message + (message (format #f (G_ "failed to authenticate \ server at '~a': ~a") - (session-get session 'host) - reason))))))) + (session-get session 'host) + reason)))))))) ;; Use public key authentication, via the SSH agent if it's available. (match (userauth-public-key/auto! session)