[bug#73654,v4] mapped-devices: luks: Support passing --allow-discards during open
Commit Message
From: Sören Tempel <soeren@soeren-tempel.net>
* gnu/system/mapped-devices.scm (open-luks-device): Support opening
LUKS devices with the --allow-discards option.
* gnu/system/mapped-devices.scm (luks-device-mapping-with-options):
Pass through the allow-discards? keyword argument.
* doc/guix.texi (Mapped Devices): Update documentation for the
luks-device-mapping-with-options procedure.
Co-authored-by: Sisiutl <sisiutl@egregore.fun>
---
Changes since v3: Fix replacement of “Solid State Disks” with “solid
state disks” in doc/guix.texi. That is, only perform this replacement
locally on the added text and not the whole document.
doc/guix.texi | 11 +++++++++-
gnu/system/mapped-devices.scm | 39 +++++++++++++++++++++--------------
2 files changed, 33 insertions(+), 17 deletions(-)
base-commit: f2b3c36bee8c232b026a66de93db38e13fbd7076
@@ -18402,7 +18402,7 @@ Mapped Devices
@code{dm-crypt} Linux kernel module.
@end defvar
-@deffn {Procedure} luks-device-mapping-with-options [#:key-file]
+@deffn {Procedure} luks-device-mapping-with-options [#:key-file #:allow-discards?]
Return a @code{luks-device-mapping} object, which defines LUKS block
device encryption using the @command{cryptsetup} command from the
package with the same name. It relies on the @code{dm-crypt} Linux
@@ -18424,6 +18424,15 @@ Mapped Devices
(type (luks-device-mapping-with-options
#:key-file "/crypto.key")))
@end lisp
+
+
+@code{allow-discards?} allows the use of discard (TRIM) requests for the
+underlying device. This is useful for solid state drives. However,
+this option can have a negative security impact because it can make
+file system level operations visible on the physical device. For more
+information, refer to the description of the @code{--allow-discards}
+option in the @code{cryptsetup-open(8)} man page.
+
@end deffn
@defvar raid-device-mapping
@@ -194,9 +194,10 @@ (define (check-device-initrd-modules device linux-modules location)
;;; Common device mappings.
;;;
-(define* (open-luks-device source targets #:key key-file)
+(define* (open-luks-device source targets #:key key-file allow-discards?)
"Return a gexp that maps SOURCE to TARGET as a LUKS device, using
-'cryptsetup'."
+'cryptsetup'. When ALLOW-DISCARDS? is true, the use of discard (TRIM) requests is
+allowed for the underlying device."
(with-imported-modules (source-module-closure
'((gnu build file-systems)
(guix build utils))) ;; For mkdir-p
@@ -234,17 +235,21 @@ (define* (open-luks-device source targets #:key key-file)
(loop (- tries-left 1))))))
(error "LUKS partition not found" source))
source)))
- ;; We want to fallback to the password unlock if the keyfile fails.
- (or (and keyfile
- (zero? (system*/tty
- #$(file-append cryptsetup-static "/sbin/cryptsetup")
- "open" "--type" "luks"
- "--key-file" keyfile
- partition #$target)))
- (zero? (system*/tty
- #$(file-append cryptsetup-static "/sbin/cryptsetup")
- "open" "--type" "luks"
- partition #$target)))))))))
+ (let ((cryptsetup-flags (cons*
+ "open" "--type" "luks" partition #$target
+ (if allow-discards?
+ '("--allow-discards")
+ '()))))
+ ;; We want to fallback to the password unlock if the keyfile fails.
+ (or (and keyfile
+ (zero?
+ (apply system*/tty
+ #$(file-append cryptsetup-static "/sbin/cryptsetup")
+ "--key-file" keyfile
+ cryptsetup-flags)))
+ (zero? (apply system*/tty
+ #$(file-append cryptsetup-static "/sbin/cryptsetup")
+ cryptsetup-flags))))))))))
(define (close-luks-device source targets)
"Return a gexp that closes TARGET, a LUKS device."
@@ -286,13 +291,15 @@ (define luks-device-mapping
((gnu build file-systems)
#:select (find-partition-by-luks-uuid system*/tty))))))
-(define* (luks-device-mapping-with-options #:key key-file)
+(define* (luks-device-mapping-with-options #:key key-file allow-discards?)
"Return a luks-device-mapping object with open modified to pass the arguments
into the open-luks-device procedure."
(mapped-device-kind
(inherit luks-device-mapping)
- (open (λ (source targets) (open-luks-device source targets
- #:key-file key-file)))))
+ (open (λ (source targets)
+ (open-luks-device source targets
+ #:key-file key-file
+ #:allow-discards? allow-discards?)))))
(define (open-raid-device sources targets)
"Return a gexp that assembles SOURCES (a list of devices) to the RAID device