* [bug#65538] [PATCH v2] services: greetd: Add pam-gnupg support.
@ 2023-08-25 14:48 guix-patches--- via
2023-10-05 12:57 ` Ludovic Courtès
0 siblings, 1 reply; 3+ messages in thread
From: guix-patches--- via @ 2023-08-25 14:48 UTC (permalink / raw)
To: 65538; +Cc: Carlos Durán Domínguez
I retry to implement the pam-gnupg module for the greetd system service. It is A PAM module that hands over your login password to gpg-agent. I added de documentation and the insert-before procedure (maybe it needs a better name), to ensure that the pam-gnupg module will be loaded at the end.
* doc/guix.texi: documentation about #:gnupg? option on (greetd-configuration).
* gnu/services.scm (insert-before): new procedure.
* gnu/services/base.scm (greetd-configuration): new option #:gnupg?.
* gnu/services/pam-mount.scm: ensure that pam mount module goes before pam gnupg module.
* gnu/system/pam.scm (pam-gnupg-module?): new procedure and ensure that pam gnupg module is at the end of (unix-pam-service).
---
doc/guix.texi | 9 +++++++++
gnu/services.scm | 11 ++++++++++-
gnu/services/base.scm | 28 ++++++++++++++++++----------
gnu/services/pam-mount.scm | 14 +++++++++-----
gnu/system/pam.scm | 13 ++++++++++---
5 files changed, 56 insertions(+), 19 deletions(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index e8c67b0cd8..1fe38bd971 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -119,6 +119,7 @@ Copyright @copyright{} 2023 Tanguy Le Carrour@*
Copyright @copyright{} 2023 Zheng Junjie@*
Copyright @copyright{} 2023 Brian Cully@*
Copyright @copyright{} 2023 Felix Lechner@*
+Copyright @copyright{} 2023 Carlos Durán Domínguez@*
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -19666,6 +19667,14 @@ A file-like object containing the ``message of the day''.
Allow empty passwords by default so that first-time users can log in when
the 'root' account has just been created.
+@item @code{gnupg?} (default: @code{#f})
+If enabled, @code{pam-gnupg} will attempt to automatically unlock the
+user's GPG keys with the login password via @code{gpg-agent}. The
+keygrips of all keys to be unlocked should be written to
+@file{~/.pam-gnupg}, and can be queried with @code{gpg -K
+--with-keygrip}. Presetting passphrases must be enabled by adding
+@code{allow-preset-passphrase} in @file{~/.gnupg/gpg-agent.conf}.
+
@item @code{terminals} (default: @code{'()})
List of @code{greetd-terminal-configuration} per terminal for which
@code{greetd} should be started.
diff --git a/gnu/services.scm b/gnu/services.scm
index eb9258977e..118b8973ff 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -129,7 +129,8 @@ (define-module (gnu services)
%boot-service
%activation-service
- etc-service) ; deprecated
+ etc-service ; deprecated
+ insert-before)
#:re-export (;; Note: Re-export 'delete' to allow for proper syntax matching
;; in 'modify-services' forms. See
;; <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26805#16>.
@@ -1248,4 +1249,12 @@ (define-syntax-rule (for-home exp ...)
(syntax-parameterize ((for-home? (identifier-syntax #t)))
exp ...))
+(define (insert-before pred lst1 lst2)
+ "Return a list appending LST2 just before the first element on LST1 that
+ satisfy the predicate PRED."
+ (cond
+ ((null? lst1) lst2)
+ ((pred (car lst1)) (append lst2 lst1))
+ (else (cons (car lst1) (insert-before pred (cdr lst1) lst2)))))
+
;;; services.scm ends here.
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index b3f2d2e8b8..34aeb4f7d2 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -21,6 +21,7 @@
;;; Copyright © 2022 Justin Veilleux <terramorpha@cock.li>
;;; Copyright © 2022 ( <paren@disroot.org>
;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
+;;; Copyright © 2023 Carlos Durán Domínguez <wurt@wurtshell.com>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -3227,6 +3228,7 @@ (define-record-type* <greetd-configuration>
greetd-configuration?
(motd greetd-motd (default %default-motd))
(allow-empty-passwords? greetd-allow-empty-passwords? (default #t))
+ (gnupg? greetd-gnupg? (default #f))
(terminals greetd-terminals (default '()))
(greeter-supplementary-groups greetd-greeter-supplementary-groups (default '())))
@@ -3266,25 +3268,31 @@ (define optional-pam-mount
(module (file-append greetd-pam-mount "/lib/security/pam_mount.so"))
(arguments '("disable_interactive"))))
+ (define (optional-pam-mount-transformer pam)
+ (if (member (pam-service-name pam)
+ '("login" "greetd" "su" "slim" "gdm-password"))
+ (pam-service
+ (inherit pam)
+ ;; SLiM could have pam-gnupg module, and pam-mount must be before it.
+ (auth (insert-before pam-gnupg-module?
+ (pam-service-auth pam)
+ (list optional-pam-mount)))
+ (session (insert-before pam-gnupg-module?
+ (pam-service-session pam)
+ (list optional-pam-mount))))
+ pam))
(list
(unix-pam-service "greetd"
#:login-uid? #t
#:allow-empty-passwords?
(greetd-allow-empty-passwords? config)
+ #:gnupg?
+ (greetd-gnupg? config)
#:motd
(greetd-motd config))
(pam-extension
(transformer
- (lambda (pam)
- (if (member (pam-service-name pam)
- '("login" "greetd" "su" "slim" "gdm-password"))
- (pam-service
- (inherit pam)
- (auth (append (pam-service-auth pam)
- (list optional-pam-mount)))
- (session (append (pam-service-session pam)
- (list optional-pam-mount))))
- pam))))))
+ optional-pam-mount-transformer))))
(define (greetd-shepherd-services config)
(map
diff --git a/gnu/services/pam-mount.scm b/gnu/services/pam-mount.scm
index b3a02e82e9..a7470e1fcb 100644
--- a/gnu/services/pam-mount.scm
+++ b/gnu/services/pam-mount.scm
@@ -1,6 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 Guillaume Le Vaillant <glv@posteo.net>
;;; Copyright © 2023 Brian Cully <bjc@spork.org>
+;;; Copyright © 2023 Carlos Durán Domínguez <wurt@wurtshell.com>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -94,7 +95,8 @@ (define (pam-mount-pam-service config)
(define optional-pam-mount
(pam-entry
(control "optional")
- (module (file-append pam-mount "/lib/security/pam_mount.so"))))
+ (module #~(string-append #$pam-mount "/lib/security/pam_mount.so"))))
+
(list
(pam-extension
(transformer
@@ -103,10 +105,12 @@ (module (file-append pam-mount "/lib/security/pam_mount.so"))))
'("login" "greetd" "su" "slim" "gdm-password" "sddm"))
(pam-service
(inherit pam)
- (auth (append (pam-service-auth pam)
- (list optional-pam-mount)))
- (session (append (pam-service-session pam)
- (list optional-pam-mount))))
+ (auth (insert-before pam-gnupg-module?
+ (pam-service-auth pam)
+ (list optional-pam-mount)))
+ (session (insert-before pam-gnupg-module?
+ (pam-service-session pam)
+ (list optional-pam-mount))))
pam))))))
(define (extend-pam-mount-configuration initial extensions)
diff --git a/gnu/system/pam.scm b/gnu/system/pam.scm
index a035a92e25..445e45c5ef 100644
--- a/gnu/system/pam.scm
+++ b/gnu/system/pam.scm
@@ -1,6 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013-2017, 2019-2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2023 Josselin Poiret <dev@jpoiret.xyz>
+;;; Copyright © 2023 Carlos Durán Domínguez <wurt@wurtshell.com>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -64,7 +65,9 @@ (define-module (gnu system pam)
pam-extension-shepherd-requirements
pam-root-service-type
- pam-root-service))
+ pam-root-service
+
+ pam-gnupg-module?))
;;; Commentary:
;;;
@@ -264,12 +267,12 @@ (module "pam_motd.so")
(control "required")
(module "pam_loginuid.so")))
'())
+ ,env ,unix
,@(if gnupg?
(list (pam-entry
(control "required")
(module (file-append pam-gnupg "/lib/security/pam_gnupg.so"))))
- '())
- ,env ,unix))))))
+ '())))))))
(define (rootok-pam-service command)
"Return a PAM service for COMMAND such that 'root' does not need to
@@ -454,4 +457,8 @@ (define* (pam-root-service base #:key (transformers '()) (shepherd-requirements
(transformers transformers)
(shepherd-requirements shepherd-requirements))))
+(define (pam-gnupg-module? name)
+ "Return `#t' if NAME is the path to the pam-gnupg module, `#f' otherwise."
+ (equal? (pam-entry-module name)
+ (file-append pam-gnupg "/lib/security/pam_gnupg.so")))
--
2.41.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [bug#65538] [PATCH v2] services: greetd: Add pam-gnupg support.
2023-08-25 14:48 [bug#65538] [PATCH v2] services: greetd: Add pam-gnupg support guix-patches--- via
@ 2023-10-05 12:57 ` Ludovic Courtès
0 siblings, 0 replies; 3+ messages in thread
From: Ludovic Courtès @ 2023-10-05 12:57 UTC (permalink / raw)
To: Carlos Durán Domínguez
Cc: Tobias Geerinckx-Rice, Simon Tournier, paren, Christopher Baines,
Ricardo Wurmus, Raghav Gururajan, jgart, Mathieu Othacehe, 65538
Hello,
Carlos Durán Domínguez <wurt@wurtshell.com> skribis:
> I retry to implement the pam-gnupg module for the greetd system service. It is A PAM module that hands over your login password to gpg-agent. I added de documentation and the insert-before procedure (maybe it needs a better name), to ensure that the pam-gnupg module will be loaded at the end.
>
> * doc/guix.texi: documentation about #:gnupg? option on (greetd-configuration).
> * gnu/services.scm (insert-before): new procedure.
> * gnu/services/base.scm (greetd-configuration): new option #:gnupg?.
> * gnu/services/pam-mount.scm: ensure that pam mount module goes before pam gnupg module.
> * gnu/system/pam.scm (pam-gnupg-module?): new procedure and ensure that pam gnupg module is at the end of (unix-pam-service).
Nice work!
A minor point: the commit log should normally lists all
changed/added/removed entities. You can use ‘git log’ to see examples,
but the committer will tweak it for you if needed (no big deal).
[...]
> +@item @code{gnupg?} (default: @code{#f})
> +If enabled, @code{pam-gnupg} will attempt to automatically unlock the
> +user's GPG keys with the login password via @code{gpg-agent}. The
> +keygrips of all keys to be unlocked should be written to
> +@file{~/.pam-gnupg}, and can be queried with @code{gpg -K
> +--with-keygrip}. Presetting passphrases must be enabled by adding
> +@code{allow-preset-passphrase} in @file{~/.gnupg/gpg-agent.conf}.
Perhaps you can add a cross-reference to the relevant part of the GnuPG
manual? (With @pxref or similar.)
> +(define (insert-before pred lst1 lst2)
> + "Return a list appending LST2 just before the first element on LST1 that
> + satisfy the predicate PRED."
> + (cond
> + ((null? lst1) lst2)
> + ((pred (car lst1)) (append lst2 lst1))
> + (else (cons (car lst1) (insert-before pred (cdr lst1) lst2)))))
I’d rather have it in (guix utils). Also, please use ‘match’ and avoid
car/cdr as per
<https://guix.gnu.org/manual/devel/en/html_node/Data-Types-and-Pattern-Matching.html>.
> (pam-service
> (inherit pam)
> - (auth (append (pam-service-auth pam)
> - (list optional-pam-mount)))
> - (session (append (pam-service-session pam)
> - (list optional-pam-mount))))
> + (auth (insert-before pam-gnupg-module?
> + (pam-service-auth pam)
> + (list optional-pam-mount)))
> + (session (insert-before pam-gnupg-module?
> + (pam-service-session pam)
> + (list optional-pam-mount))))
Could you add a comment explaining why this ordering is important?
> +(define (pam-gnupg-module? name)
> + "Return `#t' if NAME is the path to the pam-gnupg module, `#f' otherwise."
> + (equal? (pam-entry-module name)
> + (file-append pam-gnupg "/lib/security/pam_gnupg.so")))
<package> records in general cannot be compared with ‘equal?’, so the
above procedure won’t work in the general case. (It wouldn’t work with
custom variants of the ‘pam-gnupg’ package, too.)
Can you think of another way we could check whether a <pam-entry>
corresponds to ‘pam-gnupg’?
Thanks,
Ludo’.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [bug#65538] [PATCH v2] services: greetd: Add pam-gnupg support.
2023-10-06 0:53 [bug#65538] [PATCH v3] " guix-patches--- via
@ 2023-10-11 20:54 ` Ludovic Courtès
0 siblings, 0 replies; 3+ messages in thread
From: Ludovic Courtès @ 2023-10-11 20:54 UTC (permalink / raw)
To: Carlos Durán Domínguez; +Cc: 65538
Hi,
Carlos Durán Domínguez <wurt@wurtshell.com> skribis:
> My main concern is that the new 'pam-gnupg-module?' procedure could be wrong,
> but I did not find any other solution.
OK.
> I also think that using 'insert-before' in gnu/services/pam-mount.scm could be
> a problem. If other PAM modules needs to be on certain positions, it could be
> an “if mess” or maybe not, I do not know much about PAM modules.
Yeah, I’m also wondering what will happen if several services have
ordering requirements. This seems to break composability, but maybe
it’s a problem that PAM has.
> +@file{~/.pam-gnupg} (see
> +@url{https://github.com/cruegge/pam-gnupg#setup-guide, pam-gnupg setup
> +guide}), and can be queried with @code{gpg -K --with-keygrip}
> +(@pxref{Commands to select the type of operation,,,gnupg}). Presetting
> +passphrases must be enabled by adding @code{allow-preset-passphrase} in
> +@file{~/.gnupg/gpg-agent.conf} (@pxref{Put a passphrase into the
> +cache,,,gnupg}).
Note that @pxref should first name the “node” (section) of the manual
you’re referring to, and there should be one last argument giving the
title of the manual:
https://www.gnu.org/software/texinfo/manual/texinfo/html_node/Four-and-Five-Arguments.html
The ones above should be adjusted to refer to existing nodes of the
GnuPG manual.
> (if (member (pam-service-name pam)
> '("login" "greetd" "su" "slim" "gdm-password" "sddm"))
> (pam-service
> + ;; pam-mount module must be before pam-gnupg, because the later
> + ;; needs to be at the end (See pam-gnupg README.md)
> (inherit pam)
I went to look at the ‘README.md’ file, and all I could find is:
At least, `pam_gnupg.so` should come after `pam_unix.so`,
`pam_systemd_home.so`, `pam_systemd.so` and `pam_env.so` in case you
use those modules.
Is it what you’re referring to?
The ‘README.md’ also gave me a sense that pam-gnupg is not fully baked:
The code was written mainly by looking at and occasionally copying
from Gnome Keyring's PAM module and pam_mount and is based on a
somewhat mediocre understanding of the details of both PAM and C. You
should be aware that there may be potentially dangerous bugs lurking.
It also makes this recommendation, which I find dubious security-wise:
- Add
allow-preset-passphrase
to `~/.gnupg/gpg-agent.conf`. Optionally, customize the cache timeout via
`max-cache-ttl`, e.g. set
max-cache-ttl 86400
to have it expire after a day.
I guess that’s expected given the purpose of the tool, but still.
Overall that made me wonder if this is something we should promote.
WDYT?
> +(define (pam-gnupg-module? name)
> + "Return `#t' if NAME is the path to the pam-gnupg module, `#f' otherwise."
> + (let ((module (pam-entry-module name)))
> + (and (file-append? module)
> + (equal? (first (file-append-suffix module))
> + "/lib/security/pam_gnupg.so"))))
This is not ideal, because someone might give a module that’s not a
<file-append>, but I can’t think of a better way.
> - #:use-module (rnrs io ports) ;need 'port-position' etc.
> + #:use-module (rnrs io ports) ;need 'port-position' etc.
> #:use-module ((rnrs bytevectors) #:select (bytevector-u8-set!))
> #:use-module (guix memoization)
> #:use-module ((guix build utils)
> #:select (dump-port mkdir-p delete-file-recursively
> - call-with-temporary-output-file %xz-parallel-args))
> + call-with-temporary-output-file %xz-parallel-args))
> #:use-module ((guix build syscalls) #:select (mkdtemp! fdatasync))
> #:use-module ((guix combinators) #:select (fold2))
> - #:use-module (guix diagnostics) ;<location>, &error-location, etc.
> + #:use-module (guix diagnostics) ;<location>, &error-location, etc.
> #:use-module (ice-9 format)
> #:use-module ((ice-9 iconv) #:prefix iconv:)
> #:use-module (ice-9 match)
> @@ -57,7 +58,7 @@ (define-module (guix utils)
> #:use-module (ice-9 vlist)
> #:autoload (zlib) (make-zlib-input-port make-zlib-output-port)
> #:use-module (system foreign)
> - #:re-export (<location> ;for backwards compatibility
> + #:re-export (<location> ;for backwards compatibility
Unnecessary changes. :-)
Thanks,
Ludo’.
^ permalink raw reply [flat|nested] 3+ messages in thread
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