aboutsummaryrefslogtreecommitdiff
path: root/gnu/build/activation.scm
blob: beee56d43798aa158a30df5a0664448ce5881e39 (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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 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 build activation)
  #:use-module (gnu build linux-boot)
  #:use-module (guix build utils)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:export (activate-users+groups
            activate-user-home
            activate-etc
            activate-setuid-programs
            activate-special-files
            activate-modprobe
            activate-firmware
            activate-ptrace-attach
            activate-current-system))

;;; Commentary:
;;;
;;; This module provides "activation" helpers.  Activation is the process that
;;; consists in setting up system-wide files and directories so that an
;;; 'operating-system' configuration becomes active.
;;;
;;; Code:

(define (enumerate thunk)
  "Return the list of values returned by THUNK until it returned #f."
  (let loop ((entry  (thunk))
             (result '()))
    (if (not entry)
        (reverse result)
        (loop (thunk) (cons entry result)))))

(define (current-users)
  "Return the passwd entries for all the currently defined user accounts."
  (setpw)
  (enumerate getpwent))

(define (current-groups)
  "Return the group entries for all the currently defined user groups."
  (setgr)
  (enumerate getgrent))

(define* (add-group name #:key gid password system?
                    (log-port (current-error-port)))
  "Add NAME as a user group, with the given numeric GID if specified."
  ;; Use 'groupadd' from the Shadow package.
  (format log-port "adding group '~a'...~%" name)
  (let ((args `(,@(if gid `("-g" ,(number->string gid)) '())
                ,@(if password `("-p" ,password) '())
                ,@(if system? `("--system") '())
                ,name)))
    (zero? (apply system* "groupadd" args))))

(define %skeleton-directory
  ;; Directory containing skeleton files for new accounts.
  ;; Note: keep the trailing '/' so that 'scandir' enters it.
  "/etc/skel/")

(define (dot-or-dot-dot? file)
  (member file '("." "..")))

(define* (copy-account-skeletons home
                                 #:key
                                 (directory %skeleton-directory)
                                 uid gid)
  "Copy the account skeletons from DIRECTORY to HOME.  When UID is an integer,
make it the owner of all the files created; likewise for GID."
  (define (set-owner file)
    (when (or uid gid)
      (chown file (or uid -1) (or gid -1))))

  (let ((files (scandir directory (negate dot-or-dot-dot?)
                        string<?)))
    (mkdir-p home)
    (set-owner home)
    (for-each (lambda (file)
                (let ((target (string-append home "/" file)))
                  (copy-recursively (string-append directory "/" file)
                                    target
                                    #:log (%make-void-port "w"))
                  (for-each set-owner
                            (find-files target (const #t)
                                        #:directories? #t))
                  (make-file-writable target)))
              files)))

(define* (make-skeletons-writable home
                                  #:optional (directory %skeleton-directory))
  "Make sure that the files that have been copied from DIRECTORY to HOME are
owner-writable in HOME."
  (let ((files (scandir directory (negate dot-or-dot-dot?)
                        string<?)))
    (for-each (lambda (file)
                (let ((target (string-append home "/" file)))
                  (when (file-exists? target)
                    (make-file-writable target))))
              files)))

(define* (add-user name group
                   #:key uid comment home create-home?
                   shell password system?
                   (supplementary-groups '())
                   (log-port (current-error-port)))
  "Create an account for user NAME part of GROUP, with the specified
properties.  Return #t on success."
  (format log-port "adding user '~a'...~%" name)

  (if (and uid (zero? uid))

      ;; 'useradd' fails with "Cannot determine your user name" if the root
      ;; account doesn't exist.  Thus, for bootstrapping purposes, create that
      ;; one manually.
      (begin
        (call-with-output-file "/etc/shadow"
          (cut format <> "~a::::::::~%" name))
        (call-with-output-file "/etc/passwd"
          (cut format <> "~a:x:~a:~a:~a:~a:~a~%"
               name "0" "0" comment home shell))
        (chmod "/etc/shadow" #o600)
        (copy-account-skeletons (or home "/root"))
        #t)

      ;; Use 'useradd' from the Shadow package.
      (let ((args `(,@(if uid `("-u" ,(number->string uid)) '())
                    "-g" ,(if (number? group) (number->string group) group)
                    ,@(if (pair? supplementary-groups)
                          `("-G" ,(string-join supplementary-groups ","))
                          '())
                    ,@(if comment `("-c" ,comment) '())
                    ,@(if (and home create-home?)
                          (if (file-exists? home)
                              `("-d" ,home)     ; avoid warning from 'useradd'
                              `("-d" ,home "--create-home"))
                          '())
                    ,@(if shell `("-s" ,shell) '())
                    ,@(if password `("-p" ,password) '())
                    ,@(if system? '("--system") '())
                    ,name)))
        (and (zero? (apply system* "useradd" args))
             (begin
               ;; Since /etc/skel is a link to a directory in the store where
               ;; all files have the writable bit cleared, and since 'useradd'
               ;; preserves permissions when it copies them, explicitly make
               ;; them writable.
               (make-skeletons-writable home)
               #t)))))

(define* (modify-user name group
                      #:key uid comment home create-home?
                      shell password system?
                      (supplementary-groups '())
                      (log-port (current-error-port)))
  "Modify user account NAME to have all the given settings."
  ;; Use 'usermod' from the Shadow package.
  (let ((args `(,@(if uid `("-u" ,(number->string uid)) '())
                "-g" ,(if (number? group) (number->string group) group)
                ,@(if (pair? supplementary-groups)
                      `("-G" ,(string-join supplementary-groups ","))
                      '())
                ,@(if comment `("-c" ,comment) '())
                ;; Don't use '--move-home', so ignore HOME.
                ,@(if shell `("-s" ,shell) '())
                ,name)))
    (zero? (apply system* "usermod" args))))

(define* (delete-user name #:key (log-port (current-error-port)))
  "Remove user account NAME.  Return #t on success.  This may fail if NAME is
logged in."
  (format log-port "deleting user '~a'...~%" name)
  (zero? (system* "userdel" name)))

(define* (delete-group name #:key (log-port (current-error-port)))
  "Remove group NAME.  Return #t on success."
  (format log-port "deleting group '~a'...~%" name)
  (zero? (system* "groupdel" name)))

(define* (ensure-user name group
                      #:key uid comment home create-home?
                      shell password system?
                      (supplementary-groups '())
                      (log-port (current-error-port))
                      #:rest rest)
  "Make sure user NAME exists and has the relevant settings."
  (if (false-if-exception (getpwnam name))
      (apply modify-user name group rest)
      (apply add-user name group rest)))

(define (activate-users+groups users groups)
  "Make sure the accounts listed in USERS and the user groups listed in GROUPS
are all available.

Each item in USERS is a list of all the characteristics of a user account;
each item in GROUPS is a tuple with the group name, group password or #f, and
numeric gid or #f."
  (define (touch file)
    (close-port (open-file file "a0b")))

  (define activate-user
    (match-lambda
     ((name uid group supplementary-groups comment home create-home?
       shell password system?)
      (let ((profile-dir (string-append "/var/guix/profiles/per-user/"
                                        name)))
        (ensure-user name group
                     #:uid uid
                     #:system? system?
                     #:supplementary-groups supplementary-groups
                     #:comment comment
                     #:home home
                     #:create-home? (and create-home? system?)
                     #:shell shell
                     #:password password)

        (unless system?
          ;; Create the profile directory for the new account.
          (let ((pw (getpwnam name)))
            (mkdir-p profile-dir)
            (chown profile-dir (passwd:uid pw) (passwd:gid pw))))))))

  ;; 'groupadd' aborts if the file doesn't already exist.
  (touch "/etc/group")

  ;; Allow home directories to be created under /var/lib.
  (mkdir-p "/var/lib")

  ;; Create the root account so we can use 'useradd' and 'groupadd'.
  (activate-user (find (match-lambda
                        ((name (? zero?) _ ...) #t)
                        (_ #f))
                       users))

  ;; Then create the groups.
  (for-each (match-lambda
             ((name password gid system?)
              (unless (false-if-exception (getgrnam name))
                (add-group name
                           #:gid gid #:password password
                           #:system? system?))))
            groups)

  ;; Create the other user accounts.
  (for-each activate-user users)

  ;; Finally, delete extra user accounts and groups.
  (for-each delete-user
            (lset-difference string=?
                             (map passwd:name (current-users))
                             (match users
                               (((names . _) ...)
                                names))))
  (for-each delete-group
            (lset-difference string=?
                             (map group:name (current-groups))
                             (match groups
                               (((names . _) ...)
                                names)))))

(define (activate-user-home users)
  "Create and populate the home directory of USERS, a list of tuples, unless
they already exist."
  (define ensure-user-home
    (match-lambda
      ((name uid group supplementary-groups comment home create-home?
             shell password system?)
       (unless (or (not home) (directory-exists? home))
         (let* ((pw  (getpwnam name))
                (uid (passwd:uid pw))
                (gid (passwd:gid pw)))
           (mkdir-p home)
           (chown home uid gid)
           (unless system?
             (copy-account-skeletons home
                                     #:uid uid #:gid gid)))))))

  (for-each ensure-user-home users))

(define (activate-etc etc)
  "Install ETC, a directory in the store, as the source of static files for
/etc."

  ;; /etc is a mixture of static and dynamic settings.  Here is where we
  ;; initialize it from the static part.

  (define (rm-f file)
    (false-if-exception (delete-file file)))

  (format #t "populating /etc from ~a...~%" etc)

  ;; Create the /etc/ssl -> /run/current-system/profile/etc/ssl symlink.  This
  ;; symlink, to a target outside of the store, probably doesn't belong in the
  ;; static 'etc' store directory.  However, if it were to be put there,
  ;; beware that if /run/current-system/profile/etc/ssl doesn't exist at the
  ;; time of activation (e.g. when installing a fresh system), the call to
  ;; 'file-is-directory?' below will fail because it uses 'stat', not 'lstat'.
  (rm-f "/etc/ssl")
  (symlink "/run/current-system/profile/etc/ssl" "/etc/ssl")

  (rm-f "/etc/static")
  (symlink etc "/etc/static")
  (for-each (lambda (file)
              (let ((target (string-append "/etc/" file))
                    (source (string-append "/etc/static/" file)))
                (rm-f target)

                ;; Things such as /etc/sudoers must be regular files, not
                ;; symlinks; furthermore, they could be modified behind our
                ;; back---e.g., with 'visudo'.  Thus, make a copy instead of
                ;; symlinking them.
                (if (file-is-directory? source)
                    (symlink source target)
                    (copy-file source target))

                ;; XXX: Dirty hack to meet sudo's expectations.
                (when (string=? (basename target) "sudoers")
                  (chmod target #o440))))
            (scandir etc (negate dot-or-dot-dot?)

                     ;; The default is 'string-locale<?', but we don't have
                     ;; it when run from the initrd's statically-linked
                     ;; Guile.
                     string<?)))

(define %setuid-directory
  ;; Place where setuid programs are stored.
  "/run/setuid-programs")

(define (link-or-copy source target)
  "Attempt to make TARGET a hard link to SOURCE; if it fails, fall back to
copy SOURCE to TARGET."
  (catch 'system-error
    (lambda ()
      (link source target))
    (lambda args
      ;; Perhaps SOURCE and TARGET live in a different file system, so copy
      ;; SOURCE.
      (copy-file source target))))

(define (activate-setuid-programs programs)
  "Turn PROGRAMS, a list of file names, into setuid programs stored under
%SETUID-DIRECTORY."
  (define (make-setuid-program prog)
    (let ((target (string-append %setuid-directory
                                 "/" (basename prog))))
      (link-or-copy prog target)
      (chown target 0 0)
      (chmod target #o6555)))

  (format #t "setting up setuid programs in '~a'...~%"
          %setuid-directory)
  (if (file-exists? %setuid-directory)
      (for-each (compose delete-file
                         (cut string-append %setuid-directory "/" <>))
                (scandir %setuid-directory
                         (lambda (file)
                           (not (member file '("." ".."))))
                         string<?))
      (mkdir-p %setuid-directory))

  (for-each make-setuid-program programs))

(define (activate-special-files special-files)
  "Install the files listed in SPECIAL-FILES.  Each element of SPECIAL-FILES
is a pair where the first element is the name of the special file and the
second element is the name it should appear at, such as:

  ((\"/bin/sh\" \"/gnu/store/…-bash/bin/sh\")
   (\"/usr/bin/env\" \"/gnu/store/…-coreutils/bin/env\"))
"
  (define install-special-file
    (match-lambda
      ((target file)
       (let ((pivot (string-append target ".new")))
         (mkdir-p (dirname target))
         (symlink file pivot)
         (rename-file pivot target)))))

  (for-each install-special-file special-files))

(define (activate-modprobe modprobe)
  "Tell the kernel to use MODPROBE to load modules."
  (call-with-output-file "/proc/sys/kernel/modprobe"
    (lambda (port)
      (display modprobe port))))

(define (activate-firmware directory)
  "Tell the kernel to look for device firmware under DIRECTORY.  This
mechanism bypasses udev: it allows Linux to handle firmware loading directly
by itself, without having to resort to a \"user helper\"."
  (call-with-output-file "/sys/module/firmware_class/parameters/path"
    (lambda (port)
      (display directory port))))

(define (activate-ptrace-attach)
  "Allow users to PTRACE_ATTACH their own processes.

This works around a regression introduced in the default \"security\" policy
found in Linux 3.4 onward that prevents users from attaching to their own
processes--see Yama.txt in the Linux source tree for the rationale.  This
sounds like an unacceptable restriction for little or no security
improvement."
  (let ((file "/proc/sys/kernel/yama/ptrace_scope"))
    (when (file-exists? file)
      (call-with-output-file file
        (lambda (port)
          (display 0 port))))))


(define %current-system
  ;; The system that is current (a symlink.)  This is not necessarily the same
  ;; as the system we booted (aka. /run/booted-system) because we can re-build
  ;; a new system configuration and activate it, without rebooting.
  "/run/current-system")

(define (boot-time-system)
  "Return the '--system' argument passed on the kernel command line."
  (find-long-option "--system" (linux-command-line)))

(define* (activate-current-system
          #:optional (system (or (getenv "GUIX_NEW_SYSTEM")
                                 (boot-time-system))))
  "Atomically make SYSTEM the current system."
  ;; The 'GUIX_NEW_SYSTEM' environment variable is used as a way for 'guix
  ;; system reconfigure' to pass the file name of the new system.

  (format #t "making '~a' the current system...~%" system)

  ;; Atomically make SYSTEM current.
  (let ((new (string-append %current-system ".new")))
    (symlink system new)
    (rename-file new %current-system)))

;;; activation.scm ends here