gnu/installer/final.scm


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

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2019, 2020 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 installer final)
  #:use-module (gnu installer newt page)
  #:use-module (gnu installer steps)
  #:use-module (gnu installer utils)
  #:use-module (gnu installer user)
  #:use-module (gnu services herd)
  #:use-module (guix build syscalls)
  #:use-module (guix build utils)
  #:use-module (gnu build accounts)
  #:use-module ((gnu system shadow) #:prefix sys:)
  #:use-module (rnrs io ports)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 popen)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 rdelim)
  #:export (install-system))

(define %seed
  (seed->random-state
   (logxor (getpid) (car (gettimeofday)))))

(define (integer->alphanumeric-char n)
  "Map N, an integer in the [0..62] range, to an alphanumeric character."
  (cond ((< n 10)
         (integer->char (+ (char->integer #\0) n)))
        ((< n 36)
         (integer->char (+ (char->integer #\A) (- n 10))))
        ((< n 62)
         (integer->char (+ (char->integer #\a) (- n 36))))
        (else
         (error "integer out of bounds" n))))

(define (random-string len)
  "Compute a random string of size LEN where each character is alphanumeric."
  (let loop ((chars '())
             (len len))
    (if (zero? len)
        (list->string chars)
        (let ((n (random 62 %seed)))
          (loop (cons (integer->alphanumeric-char n) chars)
                (- len 1))))))

(define (create-user-database users root)
  "Create /etc/passwd, /etc/shadow, and /etc/group under ROOT for the given
USERS."
  (define etc
    (string-append root "/etc"))

  (define (salt)
    ;; "$6" gives us a SHA512 password hash; the random string must be taken
    ;; from the './0-9A-Za-z' alphabet (info "(libc) Passphrase Storage").
    (string-append "$6$" (random-string 10)))

  (define users*
    (map (lambda (user)
           (define root?
             (string=? "root" (user-name user)))

           (sys:user-account (name (user-name user))
                             (comment (user-real-name user))
                             (group "users")
                             (uid (if root? 0 #f))
                             (home-directory
                              (user-home-directory user))
                             (password (crypt (user-password user)
                                              (salt)))

                             ;; We need a string here, not a file-like, hence
                             ;; this choice.
                             (shell
                              "/run/current-system/profile/bin/bash")))
         users))

  (define-values (group password shadow)
    (user+group-databases users* sys:%base-groups
                          #:current-passwd '()
                          #:current-groups '()
                          #:current-shadow '()))

  (mkdir-p etc)
  (write-group group (string-append etc "/group"))
  (write-passwd password (string-append etc "/passwd"))
  (write-shadow shadow (string-append etc "/shadow")))

(define* (kill-cow-users cow-path #:key (spare '("udevd")))
  "Kill all processes that have references to the given COW-PATH in their
'maps' file.  The process whose names are in SPARE list are spared."
  (define %not-nul
    (char-set-complement (char-set #\nul)))

  (let ((pids
         (filter-map (lambda (pid)
                       (false-if-exception
                        (call-with-input-file
                            (string-append "/proc/" pid "/maps")
                          (lambda (port)
                            (and (string-contains (get-string-all port)
                                                  cow-path)
                                 (string->number pid))))))
                     (scandir "/proc" string->number))))
    (for-each (lambda (pid)
                ;; cmdline does not always exist.
                (false-if-exception
                 (call-with-input-file
                     (string-append "/proc/" (number->string pid) "/cmdline")
                   (lambda (port)
                     (match (string-tokenize (read-string port) %not-nul)
                       ((argv0 _ ...)
                        (unless (member (basename argv0) spare)
                          (syslog "Killing process ~a (~a)~%" pid argv0)
                          (kill pid SIGKILL)))
                       (_ #f))))))
              pids)))

(define (umount-cow-store)
  "Remove the store overlay and the bind-mount on /tmp created by the
cow-store service.  This procedure is very fragile and a better approach would
be much appreciated."
  (catch #t
    (lambda ()
      (let ((tmp-dir "/remove"))
        (syslog "Unmounting cow-store.~%")

        (mkdir-p tmp-dir)
        (mount (%store-directory) tmp-dir "" MS_MOVE)

        ;; The guix-daemon has possibly opened files from the cow-store,
        ;; restart it.
        (restart-service 'guix-daemon)

        (syslog "Killing cow users.")

        ;; Kill all processes started while the cow-store was active (logins
        ;; on other TTYs for instance).
        (kill-cow-users tmp-dir)

        ;; Try to umount the store overlay. Some process such as udevd
        ;; workers might still be active, so do some retries.
        (let loop ((try 5))
          (syslog "Umount try ~a~%" (- 5 try))
          (sleep 1)
          (let ((umounted? (false-if-exception (umount tmp-dir))))
            (if (and (not umounted?) (> try 0))
                (loop (- try 1))
                (if umounted?
                    (syslog "Umounted ~a successfully.~%" tmp-dir)
                    (syslog "Failed to umount ~a.~%" tmp-dir)))))

        (umount "/tmp")))
    (lambda args
      (syslog "~a~%" args))))

(define* (install-system locale #:key (users '()))
  "Create /etc/shadow and /etc/passwd on the installation target for USERS.
Start COW-STORE service on target directory and launch guix install command in
a subshell.  LOCALE must be the locale name under which that command will run,
or #f.  Return #t on success and #f on failure."
  (let* ((options         (catch 'system-error
                            (lambda ()
                              ;; If this file exists, it can provide
                              ;; additional command-line options.
                              (call-with-input-file
                                  "/tmp/installer-system-init-options"
                                read))
                            (const '())))
         (install-command (append (list "guix" "system" "init"
                                        "--fallback")
                                  options
                                  (list (%installer-configuration-file)
                                        (%installer-target-dir)))))
    (mkdir-p (%installer-target-dir))

    ;; We want to initialize user passwords but we don't want to store them in
    ;; the config file since the password hashes would end up world-readable
    ;; in the store.  Thus, create /etc/shadow & co. here such that, on the
    ;; first boot, the activation snippet that creates accounts will reuse the
    ;; passwords that we've put in there.
    (create-user-database users (%installer-target-dir))

    (dynamic-wind
      (lambda ()
        (start-service 'cow-store (list (%installer-target-dir))))
      (lambda ()
        ;; If there are any connected clients, assume that we are running
        ;; installation tests. In that case, dump the standard and error
        ;; outputs to syslog.
        (if (not (null? (current-clients)))
            (with-output-to-file "/dev/console"
              (lambda ()
                (with-error-to-file "/dev/console"
                  (lambda ()
                    (setvbuf (current-output-port) 'none)
                    (setvbuf (current-error-port) 'none)
                    (run-command install-command #:locale locale)))))
            (run-command install-command #:locale locale)))
      (lambda ()
        (stop-service 'cow-store)
        ;; Remove the store overlay created at cow-store service start.
        ;; Failing to do that will result in further umount calls to fail
        ;; because the target device is seen as busy. See:
        ;; https://lists.gnu.org/archive/html/guix-devel/2018-12/msg00161.html.
        (umount-cow-store)
        #f))))