d082312ef7
Requiring the user to input their password in order to unlock a device is not always reasonable, so having an option to unlock the device using a key file is a nice quality of life change. * gnu/system/mapped-devices.scm (open-luks-device): Add #:key-file argument. (luks-device-mapping-with-options): New procedure. * doc/guix.texi (Mapped Devices): Describe the new procedure. Change-Id: I1de4e045f8c2c11f9a94f1656e839c785b0c11c4 Signed-off-by: Ludovic Courtès <ludo@gnu.org>
357 lines
14 KiB
Scheme
357 lines
14 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2014-2022 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2016 Andreas Enge <andreas@enge.fr>
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;;; Copyright © 2017, 2018 Mark H Weaver <mhw@netris.org>
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;;; Copyright © 2024 Tomas Volf <~@wolfsden.cz>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu system mapped-devices)
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#:use-module (guix gexp)
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#:use-module (guix records)
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#:use-module ((guix modules) #:hide (file-name->module-name))
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#:use-module (guix i18n)
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#:use-module ((guix diagnostics)
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#:select (source-properties->location
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formatted-message
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&fix-hint
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&error-location))
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#:use-module (guix deprecation)
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#:use-module (gnu services)
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#:use-module (gnu services shepherd)
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#:use-module (gnu system uuid)
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#:autoload (gnu build file-systems) (find-partition-by-luks-uuid)
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#:autoload (gnu build linux-modules)
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(missing-modules)
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#:autoload (gnu packages cryptsetup) (cryptsetup-static)
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#:autoload (gnu packages linux) (mdadm-static lvm2-static)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-34)
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#:use-module (srfi srfi-35)
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#:use-module (ice-9 match)
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#:use-module (ice-9 format)
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#:export (%mapped-device
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mapped-device
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mapped-device?
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mapped-device-source
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mapped-device-target
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mapped-device-targets
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mapped-device-type
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mapped-device-location
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mapped-device-kind
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mapped-device-kind?
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mapped-device-kind-open
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mapped-device-kind-close
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mapped-device-kind-check
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device-mapping-service-type
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device-mapping-service
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check-device-initrd-modules ;XXX: needs a better place
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luks-device-mapping
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luks-device-mapping-with-options
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raid-device-mapping
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lvm-device-mapping))
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;;; Commentary:
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;;;
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;;; This module supports "device mapping", a concept implemented by Linux's
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;;; device-mapper.
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;;;
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;;; Code:
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(define-record-type* <mapped-device> %mapped-device
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make-mapped-device
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mapped-device?
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(source mapped-device-source) ;string | list of strings
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(targets mapped-device-targets) ;list of strings
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(type mapped-device-type) ;<mapped-device-kind>
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(location mapped-device-location
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(default (current-source-location)) (innate)))
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(define-syntax mapped-device-compatibility-helper
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(syntax-rules (target)
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((_ () (fields ...))
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(%mapped-device fields ...))
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((_ ((target exp) rest ...) (others ...))
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(%mapped-device others ...
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(targets (list exp))
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rest ...))
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((_ (field rest ...) (others ...))
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(mapped-device-compatibility-helper (rest ...)
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(others ... field)))))
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(define-syntax-rule (mapped-device fields ...)
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"Build an <mapped-device> record, automatically converting 'target' field
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specifications to 'targets'."
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(mapped-device-compatibility-helper (fields ...) ()))
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(define-deprecated (mapped-device-target md)
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mapped-device-targets
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(car (mapped-device-targets md)))
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(define-record-type* <mapped-device-type> mapped-device-kind
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make-mapped-device-kind
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mapped-device-kind?
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(open mapped-device-kind-open) ;source target -> gexp
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(close mapped-device-kind-close ;source target -> gexp
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(default (const #~(const #f))))
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(check mapped-device-kind-check ;source -> Boolean
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(default (const #t))))
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;;;
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;;; Device mapping as a Shepherd service.
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;;;
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(define device-mapping-service-type
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(shepherd-service-type
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'device-mapping
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(match-lambda
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(($ <mapped-device> source targets
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($ <mapped-device-type> open close))
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(shepherd-service
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(provision (list (symbol-append 'device-mapping- (string->symbol (string-join targets "-")))))
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(requirement '(udev))
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(documentation "Map a device node using Linux's device mapper.")
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(start #~(lambda () #$(open source targets)))
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(stop #~(lambda _ (not #$(close source targets))))
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(respawn? #f))))
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(description "Map a device node using Linux's device mapper.")))
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(define (device-mapping-service mapped-device)
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"Return a service that sets up @var{mapped-device}."
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(service device-mapping-service-type mapped-device))
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;;;
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;;; Static checks.
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;;;
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(define (check-device-initrd-modules device linux-modules location)
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"Raise an error if DEVICE needs modules beyond LINUX-MODULES to operate.
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DEVICE must be a \"/dev\" file name."
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(define missing
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;; Attempt to determine missing modules.
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(catch 'system-error
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(lambda ()
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(missing-modules device linux-modules))
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;; If we can't do that (e.g., EPERM), skip the whole thing.
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(const '())))
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(unless (null? missing)
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;; Note: What we suggest here is a list of module names (e.g.,
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;; "usb_storage"), not file names (e.g., "usb-storage.ko"). This is
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;; OK because we have machinery that accepts both the hyphen and the
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;; underscore version.
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(raise (make-compound-condition
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(formatted-message (G_ "you may need these modules \
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in the initrd for ~a:~{ ~a~}")
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device missing)
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(condition
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(&fix-hint
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(hint (format #f (G_ "Try adding them to the
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@code{initrd-modules} field of your @code{operating-system} declaration, along
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these lines:
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@example
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(operating-system
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;; @dots{}
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(initrd-modules (append (list~{ ~s~})
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%base-initrd-modules)))
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@end example
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If you think this diagnostic is inaccurate, use the @option{--skip-checks}
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option of @command{guix system}.\n")
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missing))))
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(condition
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(&error-location
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(location (source-properties->location location))))))))
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;;;
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;;; Common device mappings.
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;;;
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(define* (open-luks-device source targets #:key key-file)
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"Return a gexp that maps SOURCE to TARGET as a LUKS device, using
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'cryptsetup'."
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)
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(guix build utils))) ;; For mkdir-p
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(match targets
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((target)
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#~(let ((source #$(if (uuid? source)
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(uuid-bytevector source)
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source))
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(keyfile #$key-file))
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;; XXX: 'use-modules' should be at the top level.
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(use-modules (rnrs bytevectors) ;bytevector?
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((gnu build file-systems)
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#:select (find-partition-by-luks-uuid
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system*/tty))
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((guix build utils) #:select (mkdir-p)))
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;; Create '/run/cryptsetup/' if it does not exist, as device locking
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;; is mandatory for LUKS2.
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(mkdir-p "/run/cryptsetup/")
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;; Use 'cryptsetup-static', not 'cryptsetup', to avoid pulling the
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;; whole world inside the initrd (for when we're in an initrd).
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;; 'cryptsetup open' requires standard input to be a tty to allow
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;; for interaction but shepherd sets standard input to /dev/null;
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;; thus, explicitly request a tty.
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(let ((partition
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;; Note: We cannot use the "UUID=source" syntax here
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;; because 'cryptsetup' implements it by searching the
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;; udev-populated /dev/disk/by-id directory but udev may
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;; be unavailable at the time we run this.
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(if (bytevector? source)
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(or (let loop ((tries-left 10))
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(and (positive? tries-left)
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(or (find-partition-by-luks-uuid source)
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;; If the underlying partition is
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;; not found, try again after
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;; waiting a second, up to ten
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;; times. FIXME: This should be
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;; dealt with in a more robust way.
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(begin (sleep 1)
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(loop (- tries-left 1))))))
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(error "LUKS partition not found" source))
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source)))
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;; We want to fallback to the password unlock if the keyfile fails.
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(or (and keyfile
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(zero? (system*/tty
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#$(file-append cryptsetup-static "/sbin/cryptsetup")
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"open" "--type" "luks"
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"--key-file" keyfile
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partition #$target)))
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(zero? (system*/tty
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#$(file-append cryptsetup-static "/sbin/cryptsetup")
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"open" "--type" "luks"
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partition #$target)))))))))
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(define (close-luks-device source targets)
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"Return a gexp that closes TARGET, a LUKS device."
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(match targets
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((target)
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#~(zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
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"close" #$target)))))
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(define* (check-luks-device md #:key
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needed-for-boot?
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(initrd-modules '())
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#:allow-other-keys
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#:rest rest)
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"Ensure the source of MD is valid."
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(let ((source (mapped-device-source md))
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(location (mapped-device-location md)))
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(or (not (zero? (getuid)))
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(if (uuid? source)
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(match (find-partition-by-luks-uuid (uuid-bytevector source))
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(#f
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(raise (make-compound-condition
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(formatted-message (G_ "no LUKS partition with UUID '~a'")
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(uuid->string source))
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(condition
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(&error-location
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(location (source-properties->location
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(mapped-device-location md))))))))
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((? string? device)
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(check-device-initrd-modules device initrd-modules location)))
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(check-device-initrd-modules source initrd-modules location)))))
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(define luks-device-mapping
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;; The type of LUKS mapped devices.
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(mapped-device-kind
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(open open-luks-device)
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(close close-luks-device)
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(check check-luks-device)))
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(define* (luks-device-mapping-with-options #:key key-file)
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"Return a luks-device-mapping object with open modified to pass the arguments
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into the open-luks-device procedure."
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(mapped-device-kind
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(inherit luks-device-mapping)
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(open (λ (source targets) (open-luks-device source targets
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#:key-file key-file)))))
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(define (open-raid-device sources targets)
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"Return a gexp that assembles SOURCES (a list of devices) to the RAID device
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TARGET (e.g., \"/dev/md0\"), using 'mdadm'."
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(match targets
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((target)
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#~(let ((sources '#$sources)
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;; XXX: We're not at the top level here. We could use a
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;; non-top-level 'use-modules' form but that doesn't work when the
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;; code is eval'd, like the Shepherd does.
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(every (@ (srfi srfi-1) every))
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(format (@ (ice-9 format) format)))
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(let loop ((attempts 0))
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(unless (every file-exists? sources)
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(when (> attempts 20)
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(error "RAID devices did not show up; bailing out"
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sources))
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(format #t "waiting for RAID source devices~{ ~a~}...~%"
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sources)
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(sleep 1)
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(loop (+ 1 attempts))))
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;; Use 'mdadm-static' rather than 'mdadm' to avoid pulling its whole
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;; closure (80 MiB) in the initrd when a RAID device is needed for boot.
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(zero? (apply system* #$(file-append mdadm-static "/sbin/mdadm")
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"--assemble" #$target sources))))))
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(define (close-raid-device sources targets)
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"Return a gexp that stops the RAID device TARGET."
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(match targets
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((target)
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#~(zero? (system* #$(file-append mdadm-static "/sbin/mdadm")
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"--stop" #$target)))))
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(define raid-device-mapping
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;; The type of RAID mapped devices.
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(mapped-device-kind
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(open open-raid-device)
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(close close-raid-device)))
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(define (open-lvm-device source targets)
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#~(and
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(zero? (system* #$(file-append lvm2-static "/sbin/lvm")
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"vgchange" "--activate" "ay" #$source))
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; /dev/mapper nodes are usually created by udev, but udev may be unavailable at the time we run this. So we create them here.
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(zero? (system* #$(file-append lvm2-static "/sbin/lvm")
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"vgscan" "--mknodes"))
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(every file-exists? (map (lambda (file) (string-append "/dev/mapper/" file))
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'#$targets))))
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(define (close-lvm-device source targets)
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#~(zero? (system* #$(file-append lvm2-static "/sbin/lvm")
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"vgchange" "--activate" "n" #$source)))
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(define lvm-device-mapping
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(mapped-device-kind
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(open open-lvm-device)
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(close close-lvm-device)))
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;;; mapped-devices.scm ends here
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