From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:470:142:3::10]:39720) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icFXf-0000lt-J5 for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1icFXb-0002fN-0N for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:04 -0500 Received: from debbugs.gnu.org ([209.51.188.43]:35169) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1icFXa-0002ed-CE 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-00075V-6H for guix-patches@gnu.org; Tue, 03 Dec 2019 16:17:02 -0500 Subject: [bug#38478] [PATCH 1/4] ssh: Add 'authenticate-server*' and use it for offloading. References: <20191203210958.20936-1-ludo@gnu.org> In-Reply-To: <20191203210958.20936-1-ludo@gnu.org> Resent-Message-ID: From: Ludovic =?UTF-8?Q?Court=C3=A8s?= Date: Tue, 3 Dec 2019 22:15:54 +0100 Message-Id: <20191203211557.21145-1-ludo@gnu.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+kyle=kyleam.com@gnu.org Sender: "Guix-patches" To: 38478@debbugs.gnu.org Cc: Ludovic =?UTF-8?Q?Court=C3=A8s?= * guix/scripts/offload.scm (host-key->type+key): Remove. (open-ssh-session): Replace server authentication code with a call to 'authenticate-server*'. * guix/ssh.scm (host-key->type+key, authenticate-server*): New procedures. --- guix/scripts/offload.scm | 30 ++---------------------------- guix/ssh.scm | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 28 deletions(-) diff --git a/guix/scripts/offload.scm b/guix/scripts/offload.scm index 18473684eb..e81b6c25f2 100644 --- a/guix/scripts/offload.scm +++ b/guix/scripts/offload.scm @@ -149,19 +149,6 @@ ignoring it~%") (leave (G_ "failed to load machine file '~a': ~s~%") file args)))))) -(define (host-key->type+key host-key) - "Destructure HOST-KEY, an OpenSSH host key string, and return two values: -its key type as a symbol, and the actual base64-encoded string." - (define (type->symbol type) - (and (string-prefix? "ssh-" type) - (string->symbol (string-drop type 4)))) - - (match (string-tokenize host-key) - ((type key x) - (values (type->symbol type) key)) - ((type key) - (values (type->symbol type) key)))) - (define (private-key-from-file* file) "Like 'private-key-from-file', but raise an error that 'with-error-handling' can interpret meaningfully." @@ -203,21 +190,8 @@ private key from '~a': ~a") (build-machine-compression-level machine)))) (match (connect! session) ('ok - ;; Authenticate the server. XXX: Guile-SSH 0.10.1 doesn't know about - ;; ed25519 keys and 'get-key-type' returns #f in that case. - (let-values (((server) (get-server-public-key session)) - ((type key) (host-key->type+key - (build-machine-host-key machine)))) - (unless (and (or (not (get-key-type server)) - (eq? (get-key-type server) type)) - (string=? (public-key->string server) key)) - ;; Key mismatch: something's wrong. XXX: It could be that the server - ;; provided its Ed25519 key when we where expecting its RSA key. - (leave (G_ "server at '~a' returned host key '~a' of type '~a' \ -instead of '~a' of type '~a'~%") - (build-machine-name machine) - (public-key->string server) (get-key-type server) - key type))) + ;; Make sure the server's key is what we expect. + (authenticate-server* session (build-machine-host-key machine)) (let ((auth (userauth-public-key! session private))) (unless (eq? 'success auth) diff --git a/guix/ssh.scm b/guix/ssh.scm index 5fd3c280e8..f34e71392b 100644 --- a/guix/ssh.scm +++ b/guix/ssh.scm @@ -37,6 +37,8 @@ #:use-module (ice-9 format) #:use-module (ice-9 binary-ports) #:export (open-ssh-session + authenticate-server* + remote-inferior remote-daemon-channel connect-to-remote-daemon @@ -60,6 +62,41 @@ (define %compression "zlib@openssh.com,zlib") +(define (host-key->type+key host-key) + "Destructure HOST-KEY, an OpenSSH host key string, and return two values: +its key type as a symbol, and the actual base64-encoded string." + (define (type->symbol type) + (and (string-prefix? "ssh-" type) + (string->symbol (string-drop type 4)))) + + (match (string-tokenize host-key) + ((type key x) + (values (type->symbol type) key)) + ((type key) + (values (type->symbol type) key)))) + +(define (authenticate-server* session key) + "Make sure the server for SESSION has the given KEY, where KEY is a string +such as \"ssh-ed25519 AAAAC3Nz… root@example.org\". Raise an exception if the +actual key does not match." + (let-values (((server) (get-server-public-key session)) + ((type key) (host-key->type+key key))) + (unless (and (or (not (get-key-type server)) + (eq? (get-key-type server) type)) + (string=? (public-key->string server) key)) + ;; Key mismatch: something's wrong. XXX: It could be that the server + ;; provided its Ed25519 key when we where expecting its RSA key. XXX: + ;; Guile-SSH 0.10.1 doesn't know about ed25519 keys and 'get-key-type' + ;; returns #f in that case. + (raise (condition + (&message + (message (format #f (G_ "server at '~a' returned host key \ +'~a' of type '~a' instead of '~a' of type '~a'~%") + (session-get session 'host) + (public-key->string server) + (get-key-type server) + key type)))))))) + (define* (open-ssh-session host #:key user port identity (compression %compression) (timeout 3600)) -- 2.24.0