installer: Ask for user password and initialize /etc/shadow.

Partly fixes <https://bugs.gnu.org/35399>.

* gnu/installer/user.scm (<user>)[password]: New field.
* gnu/installer/final.scm (%seed): New variable.
(integer->alphanumeric-char, random-string)
(create-user-database): New procedures.
(install-system): Call 'create-user-database'.
* gnu/installer/newt/final.scm (run-install-shell): Add #:users and pass
it to 'install-system'.
(run-final-page): Pass #:users to 'run-install-shell'.
* gnu/installer/newt/user.scm (run-user-add-page): Add password entry.
Pass its result as the 'password' field of <user>.

4 files changed, 103 insertions, 13 deletions

diff --git a/gnu/installer/final.scm b/gnu/installer/final.scm
index 07946f72c3..4cf34d0457 100644
--- a/gnu/installer/final.scm
+++ b/gnu/installer/final.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -20,19 +21,94 @@
   #: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 utils)
+  #:use-module (gnu build accounts)
+  #:use-module ((gnu system shadow) #:prefix sys:)
+  #:use-module (rnrs io ports)
   #:export (install-system))
 
-(define (install-system locale)
-  "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."
+(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)
+           (sys:user-account (name (user-name user))
+                             (group "users")
+                             (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* (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."
   (let ((install-command
          (format #f "guix system init ~a ~a"
                  (%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))
+
     (start-service 'cow-store (list (%installer-target-dir)))
     (false-if-exception (run-shell-command install-command
                                            #:locale locale))))
diff --git a/gnu/installer/newt/final.scm b/gnu/installer/newt/final.scm
index f492c5dbb7..f470a90004 100644
--- a/gnu/installer/newt/final.scm
+++ b/gnu/installer/newt/final.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -65,10 +66,11 @@ press the button to reboot.")))
    (G_ "The final system installation step failed.  You can retry the \
 last step, or restart the installer.")))
 
-(define (run-install-shell locale)
+(define* (run-install-shell locale
+                            #:key (users '()))
   (clear-screen)
   (newt-suspend)
-  (let ((install-ok? (install-system locale)))
+  (let ((install-ok? (install-system locale #:users users)))
     (newt-resume)
     install-ok?))
 
@@ -76,12 +78,13 @@ last step, or restart the installer.")))
   (let* ((configuration   (format-configuration prev-steps result))
          (user-partitions (result-step result 'partition))
          (locale          (result-step result 'locale))
+         (users           (result-step result 'user))
          (install-ok?
           (with-mounted-partitions
            user-partitions
            (configuration->file configuration)
            (run-config-display-page)
-           (run-install-shell locale))))
+           (run-install-shell locale #:users users))))
     (if install-ok?
         (run-install-success-page)
         (run-install-failed-page))))
diff --git a/gnu/installer/newt/user.scm b/gnu/installer/newt/user.scm
index 59b1913cfc..032f9b9276 100644
--- a/gnu/installer/newt/user.scm
+++ b/gnu/installer/newt/user.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -36,10 +37,14 @@
           (make-label -1 -1 (pad-label (G_ "Name"))))
          (label-home-directory
           (make-label -1 -1 (pad-label (G_ "Home directory"))))
+         (label-password
+          (make-label -1 -1 (pad-label (G_ "Password"))))
          (entry-width 30)
          (entry-name (make-entry -1 -1 entry-width))
          (entry-home-directory (make-entry -1 -1 entry-width))
-         (entry-grid (make-grid 2 2))
+         (entry-password (make-entry -1 -1 entry-width
+                                     #:flags FLAG-PASSWORD))
+         (entry-grid (make-grid 3 4))
          (button-grid (make-grid 1 1))
          (ok-button (make-button -1 -1 (G_ "OK")))
          (grid (make-grid 1 2))
@@ -52,6 +57,8 @@
     (set-entry-grid-field 1 0 entry-name)
     (set-entry-grid-field 0 1 label-home-directory)
     (set-entry-grid-field 1 1 entry-home-directory)
+    (set-entry-grid-field 0 2 label-password)
+    (set-entry-grid-field 1 2 entry-password)
 
     (set-grid-field button-grid 0 0 GRID-ELEMENT-COMPONENT ok-button)
 
@@ -62,8 +69,8 @@
                        (string-append "/home/" (entry-value entry-name)))))
 
     (add-components-to-form form
-                            label-name label-home-directory
-                            entry-name entry-home-directory
+                            label-name label-home-directory label-password
+                            entry-name entry-home-directory entry-password
                             ok-button)
 
     (make-wrapped-grid-window (vertically-stacked-grid
@@ -82,8 +89,9 @@
             (when (eq? exit-reason 'exit-component)
               (cond
                ((components=? argument ok-button)
-                (let ((name (entry-value entry-name))
-                      (home-directory (entry-value entry-home-directory)))
+                (let ((name           (entry-value entry-name))
+                      (home-directory (entry-value entry-home-directory))
+                      (password       (entry-value entry-password)))
                   (if (or (string=? name "")
                           (string=? home-directory ""))
                       (begin
@@ -91,7 +99,8 @@
                         (run-user-add-page))
                       (user
                        (name name)
-                       (home-directory home-directory))))))))
+                       (home-directory home-directory)
+                       (password password))))))))
           (lambda ()
             (destroy-form-and-pop form)))))))
 
diff --git a/gnu/installer/user.scm b/gnu/installer/user.scm
index 1f8d40a011..fe755ad2c6 100644
--- a/gnu/installer/user.scm
+++ b/gnu/installer/user.scm
@@ -24,6 +24,7 @@
             user-name
             user-group
             user-home-directory
+            user-password
 
             users->configuration))
 
@@ -33,6 +34,7 @@
   (name            user-name)
   (group           user-group
                    (default "users"))
+  (password        user-password)
   (home-directory  user-home-directory))
 
 (define (users->configuration users)