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05/05: mapped-devices: LUKS partitions can be designated by their UUID.
From: |
Ludovic Courtès |
Subject: |
05/05: mapped-devices: LUKS partitions can be designated by their UUID. |
Date: |
Sun, 17 Apr 2016 23:24:14 +0000 |
civodul pushed a commit to branch master
in repository guix.
commit ffba7d498d36618ad21af3961a1a685ae91bae57
Author: Ludovic Courtès <address@hidden>
Date: Mon Apr 18 00:23:16 2016 +0200
mapped-devices: LUKS partitions can be designated by their UUID.
* gnu/system/mapped-devices.scm (device-mapping-service-type): Add
'modules' and 'imported-modules' fields to 'shepherd-service'.
(open-luks-device): Use 'find-partition-by-luks-uuid' to lookup the
partition when SOURCE is a bytevector.
* gnu/system/linux-initrd.scm (base-initrd): Augment 'use-modules'
form.
* doc/guix.texi (Mapped Devices): Give example with a UUID.
---
doc/guix.texi | 20 ++++++++++++++++++--
gnu/system/linux-initrd.scm | 9 ++++++++-
gnu/system/mapped-devices.scm | 29 +++++++++++++++++++++++++----
3 files changed, 51 insertions(+), 7 deletions(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index d5f7dcb..1b02ba0 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -6688,13 +6688,29 @@ Mapped devices are declared using the
@code{mapped-device} form:
(type luks-device-mapping))
@end example
address@hidden
+Or, better yet, like this:
+
address@hidden
+(mapped-device
+ (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
+ (target "home")
+ (type luks-device-mapping))
address@hidden example
+
@cindex disk encryption
@cindex LUKS
This example specifies a mapping from @file{/dev/sda3} to
@file{/dev/mapper/home} using LUKS---the
@url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
-standard mechanism for disk encryption. The @file{/dev/mapper/home}
+standard mechanism for disk encryption. In the second example, the UUID
+(unique identifier) is the LUKS UUID returned for the device by a
+command like:
+
address@hidden
+cryptsetup luksUUID /dev/sdx9
address@hidden example
+
+The @file{/dev/mapper/home}
device can then be used as the @code{device} of a @code{file-system}
declaration (@pxref{File Systems}). The @code{mapped-device} form is
detailed below.
diff --git a/gnu/system/linux-initrd.scm b/gnu/system/linux-initrd.scm
index aa9fbf6..484bce7 100644
--- a/gnu/system/linux-initrd.scm
+++ b/gnu/system/linux-initrd.scm
@@ -229,7 +229,14 @@ loaded at boot time in the order in which they appear."
(use-modules (gnu build linux-boot)
(guix build utils)
(guix build bournish) ;add the 'bournish' meta-command
- (srfi srfi-26))
+ (srfi srfi-26)
+
+ ;; FIXME: The following modules are for
+ ;; LUKS-DEVICE-MAPPING. We should instead propagate
+ ;; this info via gexps.
+ ((gnu build file-systems)
+ #:select (find-partition-by-luks-uuid))
+ (rnrs bytevectors))
(with-output-to-port (%make-void-port "w")
(lambda ()
diff --git a/gnu/system/mapped-devices.scm b/gnu/system/mapped-devices.scm
index 2706e25..450b473 100644
--- a/gnu/system/mapped-devices.scm
+++ b/gnu/system/mapped-devices.scm
@@ -22,6 +22,7 @@
#:use-module (gnu services)
#:use-module (gnu services shepherd)
#:autoload (gnu packages cryptsetup) (cryptsetup)
+ #:use-module (srfi srfi-1)
#:use-module (ice-9 match)
#:export (mapped-device
mapped-device?
@@ -77,7 +78,16 @@
(documentation "Map a device node using Linux's device mapper.")
(start #~(lambda () #$(open source target)))
(stop #~(lambda _ (not #$(close source target))))
- (respawn? #f))))))
+ (respawn? #f)
+
+ ;; Add the modules needed by LUKS-DEVICE-MAPPING.
+ ;; FIXME: This info should be propagated via gexps.
+ (modules `((rnrs bytevectors) ;bytevector?
+ ((gnu build file-systems)
+ #:select (find-partition-by-luks-uuid))
+ ,@%default-modules))
+ (imported-modules `((gnu build file-systems)
+ ,@%default-imported-modules)))))))
(define (device-mapping-service mapped-device)
"Return a service that sets up @var{mapped-device}."
@@ -91,9 +101,20 @@
(define (open-luks-device source target)
"Return a gexp that maps SOURCE to TARGET as a LUKS device, using
'cryptsetup'."
- #~(zero? (system* (string-append #$cryptsetup "/sbin/cryptsetup")
- "open" "--type" "luks"
- #$source #$target)))
+ #~(let ((source #$source))
+ (zero? (system* (string-append #$cryptsetup "/sbin/cryptsetup")
+ "open" "--type" "luks"
+
+ ;; Note: We cannot use the "UUID=source" syntax here
+ ;; because 'cryptsetup' implements it by searching the
+ ;; udev-populated /dev/disk/by-id directory but udev may
+ ;; be unavailable at the time we run this.
+ (if (bytevector? source)
+ (or (find-partition-by-luks-uuid source)
+ (error "LUKS partition not found" source))
+ source)
+
+ #$target))))
(define (close-luks-device source target)
"Return a gexp that closes TARGET, a LUKS device."