[bug#36956] [PATCH] machine: Automatically authorize the coordinator's signing key.

[Christopher Lemmer Webber]

This seems like a good usability improvement.  For clarity, I assume
that it's still configurable, however?  Would be important if pushing
builds to a different machine.

Jakob L. Kreuze writes:

> * guix/ssh.scm (remote-authorize-signing-key): New variable.
> * gnu/machine/ssh.scm (deploy-managed-host): Authorize coordinator's
> signing key before any invocations of 'remote-eval'.
> * guix/scripts/deploy.scm (guix-deploy): Display an error if a signing
> key does not exist.
> * doc/guix.texi (Invoking guix deploy): Remove section describing manual
> signing key authorization.
> ---
>  doc/guix.texi           | 16 ----------------
>  gnu/machine/ssh.scm     |  7 +++++++
>  guix/scripts/deploy.scm |  7 +++++++
>  guix/ssh.scm            | 23 +++++++++++++++++++++++
>  4 files changed, 37 insertions(+), 16 deletions(-)
>
> diff --git a/doc/guix.texi b/doc/guix.texi
> index 734206a4b2..64ca44d494 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -25530,22 +25530,6 @@ complex deployment may involve, for example, 
> starting virtual machines through
>  a Virtual Private Server (VPS) provider.  In such a case, a different
>  @var{environment} type would be used.
>  
> -Do note that you first need to generate a key pair on the coordinator machine
> -to allow the daemon to export signed archives of files from the store
> -(@pxref{Invoking guix archive}).
> -
> -@example
> -# guix archive --generate-key
> -@end example
> -
> -@noindent
> -Each target machine must authorize the key of the master machine so that it
> -accepts store items it receives from the coordinator:
> -
> -@example
> -# guix archive --authorize < coordinator-public-key.txt
> -@end example
> -
>  @deftp {Data Type} machine
>  This is the data type representing a single machine in a heterogeneous Guix
>  deployment.
> diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm
> index 1f16d9a5ea..90deff19a8 100644
> --- a/gnu/machine/ssh.scm
> +++ b/gnu/machine/ssh.scm
> @@ -28,13 +28,16 @@
>    #:use-module (guix i18n)
>    #:use-module (guix modules)
>    #:use-module (guix monads)
> +  #:use-module (guix pki)
>    #:use-module (guix records)
>    #:use-module (guix remote)
>    #:use-module (guix scripts system reconfigure)
>    #:use-module (guix ssh)
>    #:use-module (guix store)
>    #:use-module (guix utils)
> +  #:use-module (gcrypt pk-crypto)
>    #:use-module (ice-9 match)
> +  #:use-module (ice-9 textual-ports)
>    #:use-module (srfi srfi-1)
>    #:use-module (srfi srfi-19)
>    #:use-module (srfi srfi-26)
> @@ -329,6 +332,10 @@ the 'should-roll-back' field set to SHOULD-ROLL-BACK?"
>    "Internal implementation of 'deploy-machine' for MACHINE instances with an
>  environment type of 'managed-host."
>    (maybe-raise-unsupported-configuration-error machine)
> +  (remote-authorize-signing-key (call-with-input-file %public-key-file
> +                                  (lambda (port)
> +                                    (string->canonical-sexp (get-string-all 
> port))))
> +                                (machine-ssh-session machine))
>    (mlet %store-monad ((_ (check-deployment-sanity machine))
>                        (boot-parameters (machine-boot-parameters machine)))
>      (let* ((os (machine-operating-system machine))
> diff --git a/guix/scripts/deploy.scm b/guix/scripts/deploy.scm
> index 6a67985c8b..075c74d395 100644
> --- a/guix/scripts/deploy.scm
> +++ b/guix/scripts/deploy.scm
> @@ -20,6 +20,7 @@
>  (define-module (guix scripts deploy)
>    #:use-module (gnu machine)
>    #:use-module (guix discovery)
> +  #:use-module (guix pki)
>    #:use-module (guix scripts)
>    #:use-module (guix scripts build)
>    #:use-module (guix store)
> @@ -83,6 +84,12 @@ Perform the deployment specified by FILE.\n"))
>  (define (guix-deploy . args)
>    (define (handle-argument arg result)
>      (alist-cons 'file arg result))
> +
> +  (unless (file-exists? %public-key-file)
> +    (leave (G_ "no signing key '~a'
> +have you run 'guix archive --generate-key?'~%")
> +           %public-key-file))
> +
>    (let* ((opts (parse-command-line args %options (list %default-options)
>                                     #:argument-handler handle-argument))
>           (file (assq-ref opts 'file))
> diff --git a/guix/ssh.scm b/guix/ssh.scm
> index 9b5ca68894..5186c646ca 100644
> --- a/guix/ssh.scm
> +++ b/guix/ssh.scm
> @@ -21,6 +21,7 @@
>    #:use-module (guix inferior)
>    #:use-module (guix i18n)
>    #:use-module ((guix utils) #:select (&fix-hint))
> +  #:use-module (gcrypt pk-crypto)
>    #:use-module (ssh session)
>    #:use-module (ssh auth)
>    #:use-module (ssh key)
> @@ -40,6 +41,7 @@
>              remote-daemon-channel
>              connect-to-remote-daemon
>              remote-system
> +            remote-authorize-signing-key
>              send-files
>              retrieve-files
>              retrieve-files*
> @@ -289,6 +291,27 @@ the machine on the other end of SESSION."
>    (inferior-remote-eval '(begin (use-modules (guix utils)) (%current-system))
>                          session))
>  
> +(define (remote-authorize-signing-key key session)
> +  "Send KEY, a canonical sexp containing a public key, over SESSION and add 
> it
> +to the system ACL file if it has not yet been authorized."
> +  (inferior-remote-eval
> +   `(begin
> +      (use-modules (guix build utils)
> +                   (guix pki)
> +                   (guix utils)
> +                   (gcrypt pk-crypto)
> +                   (srfi srfi-26))
> +
> +      (define acl (current-acl))
> +      (define key (string->canonical-sexp ,(canonical-sexp->string key)))
> +
> +      (unless (authorized-key? key)
> +        (let ((acl (public-keys->acl (cons key (acl->public-keys acl)))))
> +          (mkdir-p (dirname %acl-file))
> +          (with-atomic-file-output %acl-file
> +            (cut write-acl acl <>)))))
> +   session))
> +
>  (define* (send-files local files remote
>                       #:key
>                       recursive?