gnu/system/mapped-devices.scm

   1 ;;; GNU Guix --- Functional package management for GNU
   2 ;;; Copyright © 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
   3 ;;; Copyright © 2016 Andreas Enge <andreas@enge.fr>
   4 ;;; Copyright © 2017, 2018 Mark H Weaver <mhw@netris.org>
   5 ;;;
   6 ;;; This file is part of GNU Guix.
   7 ;;;
   8 ;;; GNU Guix is free software; you can redistribute it and/or modify it
   9 ;;; under the terms of the GNU General Public License as published by
  10 ;;; the Free Software Foundation; either version 3 of the License, or (at
  11 ;;; your option) any later version.
  12 ;;;
  13 ;;; GNU Guix is distributed in the hope that it will be useful, but
  14 ;;; WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;;; GNU General Public License for more details.
  17 ;;;
  18 ;;; You should have received a copy of the GNU General Public License
  19 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 (define-module (gnu system mapped-devices)
  22   #:use-module (guix gexp)
  23   #:use-module (guix records)
  24   #:use-module (guix modules)
  25   #:use-module (guix i18n)
  26   #:use-module ((guix utils)
  27                 #:select (source-properties->location
  28                           &fix-hint
  29                           &error-location))
  30   #:use-module (gnu services)
  31   #:use-module (gnu services shepherd)
  32   #:use-module (gnu system uuid)
  33   #:autoload   (gnu build file-systems) (find-partition-by-luks-uuid)
  34   #:autoload   (gnu build linux-modules)
  35                  (device-module-aliases matching-modules known-module-aliases)
  36   #:autoload   (gnu packages cryptsetup) (cryptsetup-static)
  37   #:autoload   (gnu packages linux) (mdadm-static)
  38   #:use-module (srfi srfi-1)
  39   #:use-module (srfi srfi-26)
  40   #:use-module (srfi srfi-34)
  41   #:use-module (srfi srfi-35)
  42   #:use-module (ice-9 match)
  43   #:export (mapped-device
  44             mapped-device?
  45             mapped-device-source
  46             mapped-device-target
  47             mapped-device-type
  48             mapped-device-location
  49
  50             mapped-device-kind
  51             mapped-device-kind?
  52             mapped-device-kind-open
  53             mapped-device-kind-close
  54             mapped-device-kind-check
  55
  56             device-mapping-service-type
  57             device-mapping-service
  58
  59             check-device-initrd-modules           ;XXX: needs a better place
  60
  61             luks-device-mapping
  62             raid-device-mapping))
  63
  64 ;;; Commentary:
  65 ;;;
  66 ;;; This module supports "device mapping", a concept implemented by Linux's
  67 ;;; device-mapper.
  68 ;;;
  69 ;;; Code:
  70
  71 (define-record-type* <mapped-device> mapped-device
  72   make-mapped-device
  73   mapped-device?
  74   (source    mapped-device-source)                ;string | list of strings
  75   (target    mapped-device-target)                ;string
  76   (type      mapped-device-type)                  ;<mapped-device-kind>
  77   (location  mapped-device-location
  78              (default (current-source-location)) (innate)))
  79
  80 (define-record-type* <mapped-device-type> mapped-device-kind
  81   make-mapped-device-kind
  82   mapped-device-kind?
  83   (open      mapped-device-kind-open)             ;source target -> gexp
  84   (close     mapped-device-kind-close             ;source target -> gexp
  85              (default (const #~(const #f))))
  86   (check     mapped-device-kind-check             ;source -> Boolean
  87              (default (const #t))))
  88
  89 \f
  90 ;;;
  91 ;;; Device mapping as a Shepherd service.
  92 ;;;
  93
  94 (define device-mapping-service-type
  95   (shepherd-service-type
  96    'device-mapping
  97    (match-lambda
  98      (($ <mapped-device> source target
  99                          ($ <mapped-device-type> open close))
 100       (shepherd-service
 101        (provision (list (symbol-append 'device-mapping- (string->symbol target))))
 102        (requirement '(udev))
 103        (documentation "Map a device node using Linux's device mapper.")
 104        (start #~(lambda () #$(open source target)))
 105        (stop #~(lambda _ (not #$(close source target))))
 106        (respawn? #f))))))
 107
 108 (define (device-mapping-service mapped-device)
 109   "Return a service that sets up @var{mapped-device}."
 110   (service device-mapping-service-type mapped-device))
 111
 112 \f
 113 ;;;
 114 ;;; Static checks.
 115 ;;;
 116
 117 (define (check-device-initrd-modules device linux-modules location)
 118   "Raise an error if DEVICE needs modules beyond LINUX-MODULES to operate.
 119 DEVICE must be a \"/dev\" file name."
 120   (define aliases
 121     ;; Attempt to load 'modules.alias' from the current kernel, assuming we're
 122     ;; on GuixSD, and assuming that corresponds to the kernel we'll be
 123     ;; installing.  Skip the whole thing if that file cannot be read.
 124     (catch 'system-error
 125       (lambda ()
 126         (known-module-aliases))
 127       (const #f)))
 128
 129   (when aliases
 130     (let ((modules (delete-duplicates
 131                     (append-map (cut matching-modules <> aliases)
 132                                 (device-module-aliases device)))))
 133       (unless (every (cute member <> linux-modules) modules)
 134         (raise (condition
 135                 (&message
 136                  (message (format #f (G_ "you may need these modules \
 137 in the initrd for ~a:~{ ~a~}")
 138                                   device modules)))
 139                 (&fix-hint
 140                  (hint (format #f (G_ "Try adding them to the
 141 @code{initrd-modules} field of your @code{operating-system} declaration, along
 142 these lines:
 143
 144 @example
 145  (operating-system
 146    ;; @dots{}
 147    (initrd-modules (append (list~{ ~s~})
 148                            %base-initrd-modules)))
 149 @end example\n")
 150                                modules)))
 151                 (&error-location
 152                  (location (source-properties->location location)))))))))
 153
 154 \f
 155 ;;;
 156 ;;; Common device mappings.
 157 ;;;
 158
 159 (define (open-luks-device source target)
 160   "Return a gexp that maps SOURCE to TARGET as a LUKS device, using
 161 'cryptsetup'."
 162   (with-imported-modules (source-module-closure
 163                           '((gnu build file-systems)))
 164     #~(let ((source #$(if (uuid? source)
 165                           (uuid-bytevector source)
 166                           source)))
 167         ;; XXX: 'use-modules' should be at the top level.
 168         (use-modules (rnrs bytevectors)           ;bytevector?
 169                      ((gnu build file-systems)
 170                       #:select (find-partition-by-luks-uuid)))
 171
 172         ;; Use 'cryptsetup-static', not 'cryptsetup', to avoid pulling the
 173         ;; whole world inside the initrd (for when we're in an initrd).
 174         (zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
 175                         "open" "--type" "luks"
 176
 177                         ;; Note: We cannot use the "UUID=source" syntax here
 178                         ;; because 'cryptsetup' implements it by searching the
 179                         ;; udev-populated /dev/disk/by-id directory but udev may
 180                         ;; be unavailable at the time we run this.
 181                         (if (bytevector? source)
 182                             (or (let loop ((tries-left 10))
 183                                   (and (positive? tries-left)
 184                                        (or (find-partition-by-luks-uuid source)
 185                                            ;; If the underlying partition is
 186                                            ;; not found, try again after
 187                                            ;; waiting a second, up to ten
 188                                            ;; times.  FIXME: This should be
 189                                            ;; dealt with in a more robust way.
 190                                            (begin (sleep 1)
 191                                                   (loop (- tries-left 1))))))
 192                                 (error "LUKS partition not found" source))
 193                             source)
 194
 195                         #$target)))))
 196
 197 (define (close-luks-device source target)
 198   "Return a gexp that closes TARGET, a LUKS device."
 199   #~(zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
 200                     "close" #$target)))
 201
 202 (define* (check-luks-device md #:key
 203                             needed-for-boot?
 204                             (initrd-modules '())
 205                             #:allow-other-keys
 206                             #:rest rest)
 207   "Ensure the source of MD is valid."
 208   (let ((source   (mapped-device-source md))
 209         (location (mapped-device-location md)))
 210     (or (not (zero? (getuid)))
 211         (if (uuid? source)
 212             (match (find-partition-by-luks-uuid (uuid-bytevector source))
 213               (#f
 214                (raise (condition
 215                        (&message
 216                         (message (format #f (G_ "no LUKS partition with UUID '~a'")
 217                                          (uuid->string source))))
 218                        (&error-location
 219                         (location (source-properties->location
 220                                    (mapped-device-location md)))))))
 221               ((? string? device)
 222                (check-device-initrd-modules device initrd-modules location)))
 223             (check-device-initrd-modules source initrd-modules location)))))
 224
 225 (define luks-device-mapping
 226   ;; The type of LUKS mapped devices.
 227   (mapped-device-kind
 228    (open open-luks-device)
 229    (close close-luks-device)
 230    (check check-luks-device)))
 231
 232 (define (open-raid-device sources target)
 233   "Return a gexp that assembles SOURCES (a list of devices) to the RAID device
 234 TARGET (e.g., \"/dev/md0\"), using 'mdadm'."
 235   #~(let ((sources '#$sources)
 236
 237           ;; XXX: We're not at the top level here.  We could use a
 238           ;; non-top-level 'use-modules' form but that doesn't work when the
 239           ;; code is eval'd, like the Shepherd does.
 240           (every   (@ (srfi srfi-1) every))
 241           (format  (@ (ice-9 format) format)))
 242       (let loop ((attempts 0))
 243         (unless (every file-exists? sources)
 244           (when (> attempts 20)
 245             (error "RAID devices did not show up; bailing out"
 246                    sources))
 247
 248           (format #t "waiting for RAID source devices~{ ~a~}...~%"
 249                   sources)
 250           (sleep 1)
 251           (loop (+ 1 attempts))))
 252
 253       ;; Use 'mdadm-static' rather than 'mdadm' to avoid pulling its whole
 254       ;; closure (80 MiB) in the initrd when a RAID device is needed for boot.
 255       (zero? (apply system* #$(file-append mdadm-static "/sbin/mdadm")
 256                     "--assemble" #$target sources))))
 257
 258 (define (close-raid-device sources target)
 259   "Return a gexp that stops the RAID device TARGET."
 260   #~(zero? (system* #$(file-append mdadm-static "/sbin/mdadm")
 261                     "--stop" #$target)))
 262
 263 (define raid-device-mapping
 264   ;; The type of RAID mapped devices.
 265   (mapped-device-kind
 266    (open open-raid-device)
 267    (close close-raid-device)))
 268
 269 ;;; mapped-devices.scm ends here