mapped-devices: Allow unlocking by a key file.
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>
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Tomas Volf
Ludovic Courtès
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@ -123,6 +123,7 @@ Copyright @copyright{} 2023 Foundation Devices, Inc.@*
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Copyright @copyright{} 2023 Thomas Ieong@*
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Copyright @copyright{} 2023 Saku Laesvuori@*
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Copyright @copyright{} 2023 Graham James Addis@*
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Copyright @copyright{} 2023 Tomas Volf@*
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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@ -17992,6 +17993,30 @@ command from the package with the same name. It relies on the
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@code{dm-crypt} Linux kernel module.
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@end defvar
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@deffn {Procedure} luks-device-mapping-with-options [#:key-file]
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Return a @code{luks-device-mapping} object, which defines LUKS block
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device encryption using the @command{cryptsetup} command from the
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package with the same name. It relies on the @code{dm-crypt} Linux
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kernel module.
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If @code{key-file} is provided, unlocking is first attempted using that
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key file. This has an advantage of not requiring a password entry, so
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it can be used (for example) to unlock RAID arrays automatically on
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boot. If key file unlock fails, password unlock is attempted as well.
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Key file is not stored in the store and needs to be available at the
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given location at the time of the unlock attempt.
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@lisp
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;; Following definition would be equivalent to running:
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;; cryptsetup open --key-file /crypto.key /dev/sdb1 data
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(mapped-device
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(source "/dev/sdb1)
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(target "data)
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(type (luks-device-mapping-with-options
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#:key-file "/crypto.key")))
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@end lisp
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@end deffn
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@defvar raid-device-mapping
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This defines a RAID device, which is assembled using the @code{mdadm}
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command from the package with the same name. It requires a Linux kernel
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@ -2,6 +2,7 @@
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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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@ -64,6 +65,7 @@
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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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@ -188,7 +190,7 @@ option of @command{guix system}.\n")
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;;; Common device mappings.
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;;;
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(define (open-luks-device source targets)
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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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@ -198,7 +200,8 @@ option of @command{guix system}.\n")
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((target)
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#~(let ((source #$(if (uuid? source)
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(uuid-bytevector source)
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source)))
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source))
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(keyfile #$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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@ -215,29 +218,35 @@ option of @command{guix system}.\n")
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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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(zero? (system*/tty
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#$(file-append cryptsetup-static "/sbin/cryptsetup")
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"open" "--type" "luks"
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;; Note: We cannot use the "UUID=source" syntax here
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;; because 'cryptsetup' implements it by searching the
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;; udev-populated /dev/disk/by-id directory but udev may
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;; be unavailable at the time we run this.
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(if (bytevector? source)
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(or (let loop ((tries-left 10))
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(and (positive? tries-left)
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(or (find-partition-by-luks-uuid source)
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;; If the underlying partition is
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;; not found, try again after
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;; waiting a second, up to ten
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;; times. FIXME: This should be
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;; dealt with in a more robust way.
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(begin (sleep 1)
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(loop (- tries-left 1))))))
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(error "LUKS partition not found" source))
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source)
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#$target)))))))
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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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@ -276,6 +285,14 @@ option of @command{guix system}.\n")
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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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