aboutsummaryrefslogtreecommitdiff
path: root/gnu/system/file-systems.scm
blob: 2b5948256a9ed7fda775ca93a11d3e89cdc95bef (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.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 file-systems)
  #:use-module (ice-9 match)
  #:use-module (rnrs bytevectors)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-9 gnu)
  #:use-module (guix records)
  #:use-module (gnu system uuid)
  #:re-export (uuid                               ;backward compatibility
               string->uuid
               uuid->string)
  #:export (file-system
            file-system?
            file-system-device
            file-system-title                     ;deprecated
            file-system-mount-point
            file-system-type
            file-system-needed-for-boot?
            file-system-flags
            file-system-options
            file-system-mount?
            file-system-check?
            file-system-create-mount-point?
            file-system-dependencies
            file-system-location

            file-system-type-predicate

            file-system-label
            file-system-label?
            file-system-label->string

            file-system->spec
            spec->file-system
            specification->file-system-mapping

            %pseudo-file-system-types
            %fuse-control-file-system
            %binary-format-file-system
            %shared-memory-file-system
            %pseudo-terminal-file-system
            %tty-gid
            %immutable-store
            %control-groups
            %elogind-file-systems

            %base-file-systems
            %container-file-systems

            <file-system-mapping>
            file-system-mapping
            file-system-mapping?
            file-system-mapping-source
            file-system-mapping-target
            file-system-mapping-writable?

            file-system-mapping->bind-mount

            %store-mapping
            %network-configuration-files
            %network-file-mappings))

;;; Commentary:
;;;
;;; Declaring file systems to be mounted.
;;;
;;; Note: this file system is used both in the Shepherd and on the "host
;;; side", so it must not include (gnu packages …) modules.
;;;
;;; Code:

;; File system declaration.
(define-record-type* <file-system> %file-system
  make-file-system
  file-system?
  (device           file-system-device) ; string | <uuid> | <file-system-label>
  (mount-point      file-system-mount-point)      ; string
  (type             file-system-type)             ; string
  (flags            file-system-flags             ; list of symbols
                    (default '()))
  (options          file-system-options           ; string or #f
                    (default #f))
  (mount?           file-system-mount?            ; Boolean
                    (default #t))
  (needed-for-boot? %file-system-needed-for-boot? ; Boolean
                    (default #f))
  (check?           file-system-check?            ; Boolean
                    (default #t))
  (create-mount-point? file-system-create-mount-point? ; Boolean
                       (default #f))
  (dependencies     file-system-dependencies      ; list of <file-system>
                    (default '()))                ; or <mapped-device>
  (location         file-system-location
                    (default (current-source-location))
                    (innate)))

;; A file system label for use in the 'device' field.
(define-record-type <file-system-label>
  (file-system-label label)
  file-system-label?
  (label file-system-label->string))

(set-record-type-printer! <file-system-label>
                          (lambda (obj port)
                            (format port "#<file-system-label ~s>"
                                    (file-system-label->string obj))))

(define-syntax report-deprecation
  (lambda (s)
    "Report the use of the now-deprecated 'title' field."
    (syntax-case s ()
      ((_ field)
       (let* ((source (syntax-source #'field))
              (file   (and source (assq-ref source 'filename)))
              (line   (and source
                           (and=> (assq-ref source 'line) 1+)))
              (column (and source (assq-ref source 'column))))
         (format (current-error-port)
                 "~a:~a:~a: warning: 'title' field is deprecated~%"
                 file line column)
         #t)))))

;; Helper for 'process-file-system-declaration'.
(define-syntax device-expression
  (syntax-rules (quote label uuid device)
    ((_ (quote label) dev)
     (file-system-label dev))
    ((_ (quote uuid) dev)
     (if (uuid? dev) dev (uuid dev)))
    ((_ (quote device) dev)
     dev)
    ((_ title dev)
     (case title
       ((label) (file-system-label dev))
       ((uuid)  (uuid dev))
       (else    dev)))))

;; Helper to interpret the now-deprecated 'title' field.  Detect forms like
;; (title 'label), remove them, and adjust the 'device' field accordingly.
;; TODO: Remove this once 'title' has been deprecated long enough.
(define-syntax process-file-system-declaration
  (syntax-rules (device title)
    ((_ () (rest ...) #f #f)                 ;no 'title' and no 'device' field
     (%file-system rest ...))
    ((_ () (rest ...) dev #f)                     ;no 'title' field
     (%file-system rest ... (device dev)))
    ((_ () (rest ...) dev titl)                   ;got a 'title' field
     (%file-system rest ...
                   (device (device-expression titl dev))))
    ((_ ((title titl) rest ...) (previous ...) dev _)
     (begin
       (report-deprecation (title titl))
       (process-file-system-declaration (rest ...)
                                        (previous ...)
                                        dev titl)))
    ((_ ((device dev) rest ...) (previous ...) _ titl)
     (process-file-system-declaration (rest ...)
                                      (previous ...)
                                      dev titl))
    ((_ (field rest ...) (previous ...) dev titl)
     (process-file-system-declaration (rest ...)
                                      (previous ... field)
                                      dev titl))))

(define-syntax-rule (file-system fields ...)
  (process-file-system-declaration (fields ...) () #f #f))

(define (file-system-title fs)                    ;deprecated
  (match (file-system-device fs)
    ((? file-system-label?) 'label)
    ((? uuid?)              'uuid)
    ((? string?)            'device)))

;; Note: This module is used both on the build side and on the host side.
;; Arrange not to pull (guix store) and (guix config) because the latter
;; differs from user to user.
(define (%store-prefix)
  "Return the store prefix."
  (cond ((resolve-module '(guix store) #:ensure #f)
         =>
         (lambda (store)
           ((module-ref store '%store-prefix))))
        ((getenv "NIX_STORE")
         => identity)
        (else
         "/gnu/store")))

(define %not-slash
  (char-set-complement (char-set #\/)))

(define (file-prefix? file1 file2)
  "Return #t if FILE1 denotes the name of a file that is a parent of FILE2,
where both FILE1 and FILE2 are absolute file name.  For example:

  (file-prefix? \"/gnu\" \"/gnu/store\")
  => #t

  (file-prefix? \"/gn\" \"/gnu/store\")
  => #f
"
  (and (string-prefix? "/" file1)
       (string-prefix? "/" file2)
       (let loop ((file1 (string-tokenize file1 %not-slash))
                  (file2 (string-tokenize file2 %not-slash)))
         (match file1
           (()
            #t)
           ((head1 tail1 ...)
            (match file2
              ((head2 tail2 ...)
               (and (string=? head1 head2) (loop tail1 tail2)))
              (()
               #f)))))))

(define (file-system-needed-for-boot? fs)
  "Return true if FS has the 'needed-for-boot?' flag set, or if it holds the
store--e.g., if FS is the root file system."
  (or (%file-system-needed-for-boot? fs)
      (and (file-prefix? (file-system-mount-point fs) (%store-prefix))
           (not (memq 'bind-mount (file-system-flags fs))))))

(define (file-system->spec fs)
  "Return a list corresponding to file-system FS that can be passed to the
initrd code."
  (match fs
    (($ <file-system> device mount-point type flags options _ _ check?)
     (list (cond ((uuid? device)
                  `(uuid ,(uuid-type device) ,(uuid-bytevector device)))
                 ((file-system-label? device)
                  `(file-system-label ,(file-system-label->string device)))
                 (else device))
           mount-point type flags options check?))))

(define (spec->file-system sexp)
  "Deserialize SEXP, a list, to the corresponding <file-system> object."
  (match sexp
    ((device mount-point type flags options check?)
     (file-system
       (device (match device
                 (('uuid (? symbol? type) (? bytevector? bv))
                  (bytevector->uuid bv type))
                 (('file-system-label (? string? label))
                  (file-system-label label))
                 (_
                  device)))
       (mount-point mount-point) (type type)
       (flags flags) (options options)
       (check? check?)))))

(define (specification->file-system-mapping spec writable?)
  "Read the SPEC and return the corresponding <file-system-mapping>.  SPEC is
a string of the form \"SOURCE\" or \"SOURCE=TARGET\".  The former specifies
that SOURCE from the host should be mounted at SOURCE in the other system.
The latter format specifies that SOURCE from the host should be mounted at
TARGET in the other system."
  (let ((index (string-index spec #\=)))
    (if index
        (file-system-mapping
         (source (substring spec 0 index))
         (target (substring spec (+ 1 index)))
         (writable? writable?))
        (file-system-mapping
         (source spec)
         (target spec)
         (writable? writable?)))))


;;;
;;; Common file systems.
;;;

(define %pseudo-file-system-types
  ;; List of know pseudo file system types.  This is used when validating file
  ;; system definitions.
  '("binfmt_misc" "cgroup" "debugfs" "devpts" "devtmpfs" "efivarfs" "fusectl"
    "hugetlbfs" "overlay" "proc" "securityfs" "sysfs" "tmpfs"))

(define %fuse-control-file-system
  ;; Control file system for Linux' file systems in user-space (FUSE).
  (file-system
    (device "fusectl")
    (mount-point "/sys/fs/fuse/connections")
    (type "fusectl")
    (check? #f)))

(define %binary-format-file-system
  ;; Support for arbitrary executable binary format.
  (file-system
    (device "binfmt_misc")
    (mount-point "/proc/sys/fs/binfmt_misc")
    (type "binfmt_misc")
    (check? #f)))

(define %tty-gid
  ;; ID of the 'tty' group.  Allocate it statically to make it easy to refer
  ;; to it from here and from the 'tty' group definitions.
  996)

(define %pseudo-terminal-file-system
  ;; The pseudo-terminal file system.  It needs to be mounted so that
  ;; statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3) expects (and
  ;; thus openpty(3) and its users, such as xterm.)
  (file-system
    (device "none")
    (mount-point "/dev/pts")
    (type "devpts")
    (check? #f)
    (needed-for-boot? #f)
    (create-mount-point? #t)
    (options (string-append "gid=" (number->string %tty-gid) ",mode=620"))))

(define %shared-memory-file-system
  ;; Shared memory.
  (file-system
    (device "tmpfs")
    (mount-point "/dev/shm")
    (type "tmpfs")
    (check? #f)
    (flags '(no-suid no-dev))
    (options "size=50%")                         ;TODO: make size configurable
    (create-mount-point? #t)))

(define %immutable-store
  ;; Read-only store to avoid users or daemons accidentally modifying it.
  ;; 'guix-daemon' has provisions to remount it read-write in its own name
  ;; space.
  (file-system
    (device (%store-prefix))
    (mount-point (%store-prefix))
    (type "none")
    (check? #f)
    (flags '(read-only bind-mount))))

(define %control-groups
  (let ((parent (file-system
                  (device "cgroup")
                  (mount-point "/sys/fs/cgroup")
                  (type "tmpfs")
                  (check? #f))))
    (cons parent
          (map (lambda (subsystem)
                 (file-system
                   (device "cgroup")
                   (mount-point (string-append "/sys/fs/cgroup/" subsystem))
                   (type "cgroup")
                   (check? #f)
                   (options subsystem)
                   (create-mount-point? #t)

                   ;; This must be mounted after, and unmounted before the
                   ;; parent directory.
                   (dependencies (list parent))))
               '("cpuset" "cpu" "cpuacct" "memory" "devices" "freezer"
                 "blkio" "perf_event")))))

(define %elogind-file-systems
  ;; We don't use systemd, but these file systems are needed for elogind,
  ;; which was extracted from systemd.
  (append
   (list (file-system
           (device "none")
           (mount-point "/run/systemd")
           (type "tmpfs")
           (check? #f)
           (flags '(no-suid no-dev no-exec))
           (options "mode=0755")
           (create-mount-point? #t))
         (file-system
           (device "none")
           (mount-point "/run/user")
           (type "tmpfs")
           (check? #f)
           (flags '(no-suid no-dev no-exec))
           (options "mode=0755")
           (create-mount-point? #t))
         ;; Elogind uses cgroups to organize processes, allowing it to map PIDs
         ;; to sessions.  Elogind's cgroup hierarchy isn't associated with any
         ;; resource controller ("subsystem").
         (file-system
           (device "cgroup")
           (mount-point "/sys/fs/cgroup/elogind")
           (type "cgroup")
           (check? #f)
           (options "none,name=elogind")
           (create-mount-point? #t)
           (dependencies (list (car %control-groups)))))
   %control-groups))

(define %base-file-systems
  ;; List of basic file systems to be mounted.  Note that /proc and /sys are
  ;; currently mounted by the initrd.
  (list %pseudo-terminal-file-system
        %shared-memory-file-system
        %immutable-store))

;; File systems for Linux containers differ from %base-file-systems in that
;; they impose additional restrictions such as no-exec or need different
;; options to function properly.
;;
;; The file system flags and options conform to the libcontainer
;; specification:
;; https://github.com/docker/libcontainer/blob/master/SPEC.md#filesystem
(define %container-file-systems
  (list
   ;; Pseudo-terminal file system.
   (file-system
     (device "none")
     (mount-point "/dev/pts")
     (type "devpts")
     (flags '(no-exec no-suid))
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f)
     (options "newinstance,ptmxmode=0666,mode=620"))
   ;; Shared memory file system.
   (file-system
     (device "tmpfs")
     (mount-point "/dev/shm")
     (type "tmpfs")
     (flags '(no-exec no-suid no-dev))
     (options "mode=1777,size=65536k")
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f))
   ;; Message queue file system.
   (file-system
     (device "mqueue")
     (mount-point "/dev/mqueue")
     (type "mqueue")
     (flags '(no-exec no-suid no-dev))
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f))))


;;;
;;; Shared file systems, for VMs/containers.
;;;

;; Mapping of host file system SOURCE to mount point TARGET in the guest.
(define-record-type* <file-system-mapping> file-system-mapping
  make-file-system-mapping
  file-system-mapping?
  (source    file-system-mapping-source)          ;string
  (target    file-system-mapping-target)          ;string
  (writable? file-system-mapping-writable?        ;Boolean
             (default #f)))

(define (file-system-mapping->bind-mount mapping)
  "Return a file system that realizes MAPPING, a <file-system-mapping>, using
a bind mount."
  (match mapping
    (($ <file-system-mapping> source target writable?)
     (file-system
       (mount-point target)
       (device source)
       (type "none")
       (flags (if writable?
                  '(bind-mount)
                  '(bind-mount read-only)))
       (check? #f)
       (create-mount-point? #t)))))

(define %store-mapping
  ;; Mapping of the host's store into the guest.
  (file-system-mapping
   (source (%store-prefix))
   (target (%store-prefix))
   (writable? #f)))

(define %network-configuration-files
  ;; List of essential network configuration files.
  '("/etc/resolv.conf"
    "/etc/nsswitch.conf"
    "/etc/services"
    "/etc/hosts"))

(define %network-file-mappings
  ;; List of file mappings for essential network files.
  (filter-map (lambda (file)
                (file-system-mapping
                 (source file)
                 (target file)
                 ;; XXX: On some GNU/Linux systems, /etc/resolv.conf is a
                 ;; symlink to a file in a tmpfs which, for an unknown reason,
                 ;; cannot be bind mounted read-only within the container.
                 (writable? (string=? file "/etc/resolv.conf"))))
              %network-configuration-files))

(define (file-system-type-predicate type)
  "Return a predicate that, when passed a file system, returns #t if that file
system has the given TYPE."
  (lambda (fs)
    (string=? (file-system-type fs) type)))

;;; file-systems.scm ends here