aboutsummaryrefslogtreecommitdiff
path: root/gnu/system/linux.scm
blob: 5440f5852fd5dae62379aee84e22af31d4eb1f4a (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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014 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 linux)
  #:use-module (guix store)
  #:use-module (guix records)
  #:use-module (guix derivations)
  #:use-module (guix monads)
  #:use-module (guix gexp)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:use-module ((guix utils) #:select (%current-system))
  #:export (pam-service
            pam-entry
            pam-services->directory
            unix-pam-service
            base-pam-services))

;;; Commentary:
;;;
;;; Configuration of Linux-related things, including pluggable authentication
;;; modules (PAM).
;;;
;;; Code:

;; PAM services (see
;; <http://www.linux-pam.org/Linux-PAM-html/sag-configuration-file.html>.)
(define-record-type* <pam-service> pam-service
  make-pam-service
  pam-service?
  (name       pam-service-name)                   ; string

  ;; The four "management groups".
  (account    pam-service-account                 ; list of <pam-entry>
              (default '()))
  (auth       pam-service-auth
              (default '()))
  (password   pam-service-password
              (default '()))
  (session    pam-service-session
              (default '())))

(define-record-type* <pam-entry> pam-entry
  make-pam-entry
  pam-entry?
  (control    pam-entry-control)         ; string
  (module     pam-entry-module)          ; file name
  (arguments  pam-entry-arguments        ; list of string-valued g-expressions
              (default '())))

(define (pam-service->configuration service)
  "Return the derivation building the configuration file for SERVICE, to be
dumped in /etc/pam.d/NAME, where NAME is the name of SERVICE."
  (define (entry->gexp type entry)
    (match entry
      (($ <pam-entry> control module (arguments ...))
       #~(format #t "~a ~a ~a ~a~%"
                 #$type #$control #$module
                 (string-join (list #$@arguments))))))

  (match service
    (($ <pam-service> name account auth password session)
     (define builder
       #~(begin
           (with-output-to-file #$output
             (lambda ()
               #$@(append (map (cut entry->gexp "account" <>) account)
                          (map (cut entry->gexp "auth" <>) auth)
                          (map (cut entry->gexp "password" <>) password)
                          (map (cut entry->gexp "session" <>) session))
               #t))))

     (gexp->derivation name builder))))

(define (pam-services->directory services)
  "Return the derivation to build the configuration directory to be used as
/etc/pam.d for SERVICES."
  (mlet %store-monad
      ((names -> (map pam-service-name services))
       (files (sequence %store-monad
                        (map pam-service->configuration
                             ;; XXX: Eventually, SERVICES may be a list of
                             ;; monadic values instead of plain values.
                             services))))
    (define builder
      #~(begin
          (use-modules (ice-9 match))

          (mkdir #$output)
          (for-each (match-lambda
                     ((name file)
                      (symlink file (string-append #$output "/" name))))
                    '#$(zip names files))))

    (gexp->derivation "pam.d" builder)))

(define %pam-other-services
  ;; The "other" PAM configuration, which denies everything (see
  ;; <http://www.linux-pam.org/Linux-PAM-html/sag-configuration-example.html>.)
  (let ((deny (pam-entry
               (control "required")
               (module "pam_deny.so"))))
    (pam-service
     (name "other")
     (account (list deny))
     (auth (list deny))
     (password (list deny))
     (session (list deny)))))

(define unix-pam-service
  (let ((unix (pam-entry
               (control "required")
               (module "pam_unix.so"))))
    (lambda* (name #:key allow-empty-passwords? motd)
      "Return a standard Unix-style PAM service for NAME.  When
ALLOW-EMPTY-PASSWORDS? is true, allow empty passwords.  When MOTD is true, it
should be the name of a file used as the message-of-the-day."
      ;; See <http://www.linux-pam.org/Linux-PAM-html/sag-configuration-example.html>.
      (let ((name* name))
        (pam-service
         (name name*)
         (account (list unix))
         (auth (list (if allow-empty-passwords?
                         (pam-entry
                          (control "required")
                          (module "pam_unix.so")
                          (arguments '("nullok")))
                         unix)))
         (password (list unix))
         (session (if motd
                      (list unix
                            (pam-entry
                             (control "optional")
                             (module "pam_motd.so")
                             (arguments
                              (list #~(string-append "motd=" #$motd)))))
                      (list unix))))))))

(define* (base-pam-services #:key allow-empty-passwords?)
  "Return the list of basic PAM services everyone would want."
  (cons %pam-other-services
        (map (cut unix-pam-service <>
                  #:allow-empty-passwords? allow-empty-passwords?)
             '("su" "passwd" "sudo"
               "useradd" "userdel" "usermod"
               "groupadd" "groupdel" "groupmod"
               ;; TODO: Add other Shadow programs?
               ))))

;;; linux.scm ends here