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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Andreas Enge <andreas@enge.fr>
;;; Copyright © 2017 Mark H Weaver <mhw@netris.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu system mapped-devices)
#:use-module (guix gexp)
#:use-module (guix records)
#:use-module (guix modules)
#:use-module (guix i18n)
#:use-module ((guix utils)
#:select (source-properties->location
&error-location))
#:use-module (gnu services)
#:use-module (gnu services shepherd)
#:use-module (gnu system uuid)
#:autoload (gnu build file-systems) (find-partition-by-luks-uuid)
#:autoload (gnu packages cryptsetup) (cryptsetup-static)
#:autoload (gnu packages linux) (mdadm-static)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 match)
#:export (mapped-device
mapped-device?
mapped-device-source
mapped-device-target
mapped-device-type
mapped-device-location
mapped-device-kind
mapped-device-kind?
mapped-device-kind-open
mapped-device-kind-close
mapped-device-kind-check
device-mapping-service-type
device-mapping-service
luks-device-mapping
raid-device-mapping))
;;; Commentary:
;;;
;;; This module supports "device mapping", a concept implemented by Linux's
;;; device-mapper.
;;;
;;; Code:
(define-record-type* <mapped-device> mapped-device
make-mapped-device
mapped-device?
(source mapped-device-source) ;string | list of strings
(target mapped-device-target) ;string
(type mapped-device-type) ;<mapped-device-kind>
(location mapped-device-location
(default (current-source-location)) (innate)))
(define-record-type* <mapped-device-type> mapped-device-kind
make-mapped-device-kind
mapped-device-kind?
(open mapped-device-kind-open) ;source target -> gexp
(close mapped-device-kind-close ;source target -> gexp
(default (const #~(const #f))))
(check mapped-device-kind-check ;source -> Boolean
(default (const #t))))
;;;
;;; Device mapping as a Shepherd service.
;;;
(define device-mapping-service-type
(shepherd-service-type
'device-mapping
(match-lambda
(($ <mapped-device> source target
($ <mapped-device-type> open close))
(shepherd-service
(provision (list (symbol-append 'device-mapping- (string->symbol target))))
(requirement '(udev))
(documentation "Map a device node using Linux's device mapper.")
(start #~(lambda () #$(open source target)))
(stop #~(lambda _ (not #$(close source target))))
(respawn? #f))))))
(define (device-mapping-service mapped-device)
"Return a service that sets up @var{mapped-device}."
(service device-mapping-service-type mapped-device))
;;;
;;; Common device mappings.
;;;
(define (open-luks-device source target)
"Return a gexp that maps SOURCE to TARGET as a LUKS device, using
'cryptsetup'."
(with-imported-modules (source-module-closure
'((gnu build file-systems)))
#~(let ((source #$(if (uuid? source)
(uuid-bytevector source)
source)))
;; XXX: 'use-modules' should be at the top level.
(use-modules (rnrs bytevectors) ;bytevector?
((gnu build file-systems)
#:select (find-partition-by-luks-uuid)))
;; Use 'cryptsetup-static', not 'cryptsetup', to avoid pulling the
;; whole world inside the initrd (for when we're in an initrd).
(zero? (system* #$(file-append cryptsetup-static "/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 (let loop ((tries-left 10))
(and (positive? tries-left)
(or (find-partition-by-luks-uuid source)
;; If the underlying partition is
;; not found, try again after
;; waiting a second, up to ten
;; times. FIXME: This should be
;; dealt with in a more robust way.
(begin (sleep 1)
(loop (- tries-left 1))))))
(error "LUKS partition not found" source))
source)
#$target)))))
(define (close-luks-device source target)
"Return a gexp that closes TARGET, a LUKS device."
#~(zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
"close" #$target)))
(define (check-luks-device md)
"Ensure the source of MD is valid."
(let ((source (mapped-device-source md)))
(or (not (uuid? source))
(not (zero? (getuid)))
(find-partition-by-luks-uuid (uuid-bytevector source))
(raise (condition
(&message
(message (format #f (G_ "no LUKS partition with UUID '~a'")
(uuid->string source))))
(&error-location
(location (source-properties->location
(mapped-device-location md)))))))))
(define luks-device-mapping
;; The type of LUKS mapped devices.
(mapped-device-kind
(open open-luks-device)
(close close-luks-device)
(check check-luks-device)))
(define (open-raid-device sources target)
"Return a gexp that assembles SOURCES (a list of devices) to the RAID device
TARGET (e.g., \"/dev/md0\"), using 'mdadm'."
#~(let ((sources '#$sources)
;; XXX: We're not at the top level here. We could use a
;; non-top-level 'use-modules' form but that doesn't work when the
;; code is eval'd, like the Shepherd does.
(every (@ (srfi srfi-1) every))
(format (@ (ice-9 format) format)))
(let loop ((attempts 0))
(unless (every file-exists? sources)
(when (> attempts 20)
(error "RAID devices did not show up; bailing out"
sources))
(format #t "waiting for RAID source devices~{ ~a~}...~%"
sources)
(sleep 1)
(loop (+ 1 attempts))))
;; Use 'mdadm-static' rather than 'mdadm' to avoid pulling its whole
;; closure (80 MiB) in the initrd when a RAID device is needed for boot.
(zero? (apply system* #$(file-append mdadm-static "/sbin/mdadm")
"--assemble" #$target sources))))
(define (close-raid-device sources target)
"Return a gexp that stops the RAID device TARGET."
#~(zero? (system* #$(file-append mdadm-static "/sbin/mdadm")
"--stop" #$target)))
(define raid-device-mapping
;; The type of RAID mapped devices.
(mapped-device-kind
(open open-raid-device)
(close close-raid-device)))
;;; mapped-devices.scm ends here
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