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
|
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2010, 2011, 2013, 2014, 2016, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
;;; Copyright © 2020 Tobias Geerinckx-Rice <me@tobias.gr>
;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; 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 (guix gnupg)
#:use-module (ice-9 popen)
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 i18n)
#:use-module (srfi srfi-1)
#:use-module (guix i18n)
#:use-module ((guix utils) #:select (config-directory))
#:use-module ((guix build utils) #:select (mkdir-p))
#:export (%gpg-command
%openpgp-key-server
current-keyring
gnupg-verify
gnupg-verify*
gnupg-status-good-signature?
gnupg-status-missing-key?))
;;; Commentary:
;;;
;;; GnuPG interface.
;;;
;;; Code:
(define %gpg-command
;; The GnuPG 2.x command-line program name.
(make-parameter (or (getenv "GUIX_GPG_COMMAND") "gpg")))
(define %gpgv-command
;; The 'gpgv' program.
(make-parameter (or (getenv "GUIX_GPGV_COMMAND") "gpgv")))
(define current-keyring
;; The default keyring of "trusted keys".
(make-parameter (string-append (config-directory #:ensure? #f)
"/gpg/trustedkeys.kbx")))
(define %openpgp-key-server
;; The default key server. It defaults to #f, which causes GnuPG to use the
;; one it is configured with.
(make-parameter #f))
;; Regexps for status lines. See file `doc/DETAILS' in GnuPG.
(define sigid-rx
(make-regexp
"^\\[GNUPG:\\] SIG_ID ([A-Za-z0-9+/]+) ([[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}) ([[:digit:]]+)"))
(define goodsig-rx
(make-regexp "^\\[GNUPG:\\] GOODSIG ([[:xdigit:]]+) (.+)$"))
(define validsig-rx
(make-regexp
"^\\[GNUPG:\\] VALIDSIG ([[:xdigit:]]+) ([[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}) ([[:digit:]]+) .*$"))
(define expkeysig-rx ; good signature, but expired key
(make-regexp "^\\[GNUPG:\\] EXPKEYSIG ([[:xdigit:]]+) (.*)$"))
(define revkeysig-rx ; good signature, but revoked key
(make-regexp "^\\[GNUPG:\\] REVKEYSIG ([[:xdigit:]]+) (.*)$"))
(define errsig-rx
;; Note: The fingeprint part (the last element of the line) appeared in
;; GnuPG 2.2.7 according to 'doc/DETAILS', and it may be missing.
(make-regexp
"^\\[GNUPG:\\] ERRSIG ([[:xdigit:]]+) ([^ ]+) ([^ ]+) ([^ ]+) ([[:digit:]]+) ([[:digit:]]+)(.*)"))
(define* (gnupg-verify sig file
#:optional (keyring (current-keyring)))
"Verify signature SIG for FILE against the keys in KEYRING. All the keys in
KEYRING as assumed to be \"trusted\", whether or not they expired or were
revoked. Return a status s-exp if GnuPG failed."
(define (maybe-fingerprint str)
(match (string-trim-both str)
((or "-" "") #f)
(fpr fpr)))
(define (status-line->sexp line)
(cond ((regexp-exec sigid-rx line)
=>
(lambda (match)
`(signature-id ,(match:substring match 1) ; sig id
,(match:substring match 2) ; date
,(string->number ; timestamp
(match:substring match 3)))))
((regexp-exec goodsig-rx line)
=>
(lambda (match)
`(good-signature ,(match:substring match 1) ; key id
,(match:substring match 2)))) ; user name
((regexp-exec validsig-rx line)
=>
(lambda (match)
`(valid-signature ,(match:substring match 1) ; fingerprint
,(match:substring match 2) ; sig creation date
,(string->number ; timestamp
(match:substring match 3)))))
((regexp-exec expkeysig-rx line)
=>
(lambda (match)
`(expired-key-signature ,(match:substring match 1) ; fingerprint
,(match:substring match 2)))) ; user name
((regexp-exec revkeysig-rx line)
=>
(lambda (match)
`(revoked-key-signature ,(match:substring match 1) ; fingerprint
,(match:substring match 2)))) ; user name
((regexp-exec errsig-rx line)
=>
(lambda (match)
`(signature-error ,(match:substring match 1) ; key id
,(match:substring match 2) ; pubkey algo
,(match:substring match 3) ; hash algo
,(match:substring match 4) ; sig class
,(string->number ; timestamp
(match:substring match 5))
,(let ((rc
(string->number ; return code
(match:substring match 6))))
(case rc
((9) 'missing-key)
((4) 'unknown-algorithm)
(else rc)))
,(maybe-fingerprint ; fingerprint or #f
(match:substring match 7)))))
(else
`(unparsed-line ,line))))
(define (parse-status input)
(let loop ((line (read-line input))
(result '()))
(if (eof-object? line)
(reverse result)
(loop (read-line input)
(cons (status-line->sexp line) result)))))
(let* ((pipe (open-pipe* OPEN_READ (%gpgv-command) "--status-fd=1"
"--keyring" keyring sig file))
(status (parse-status pipe)))
;; Ignore PIPE's exit status since STATUS above should contain all the
;; info we need.
(close-pipe pipe)
status))
(define (gnupg-status-good-signature? status)
"If STATUS, as returned by `gnupg-verify', denotes a good signature, return
a fingerprint/user pair; return #f otherwise."
(match (assq 'valid-signature status)
(('valid-signature fingerprint date timestamp)
(match (or (assq 'good-signature status)
(assq 'expired-key-signature status)
(assq 'revoked-key-signature status))
((_ key-id user) (cons fingerprint user))
(_ #f)))
(_
#f)))
(define (gnupg-status-missing-key? status)
"If STATUS denotes a missing-key error, then return the fingerprint of the
missing key or its key id if the fingerprint is unavailable."
(any (lambda (sexp)
(match sexp
(('signature-error key-id _ ... 'missing-key fingerprint)
(or fingerprint key-id))
(_ #f)))
status))
(define* (gnupg-receive-keys fingerprint/key-id
#:key server (keyring (current-keyring)))
"Download FINGERPRINT/KEY-ID from SERVER if specified, otherwise from
GnuPG's default/configured one. The key is added to KEYRING."
(unless (file-exists? keyring)
(mkdir-p (dirname keyring))
(call-with-output-file keyring (const #t))) ;create an empty keybox
(zero? (apply system*
`(,(%gpg-command)
,@(if server
(list "--keyserver" server)
'())
"--no-default-keyring" "--keyring" ,keyring
"--recv-keys" ,fingerprint/key-id))))
(define* (gnupg-verify* sig file
#:key
(key-download 'interactive)
server
(keyring (current-keyring)))
"Like `gnupg-verify', but try downloading the public key if it's missing.
Return two values: 'valid-signature and a fingerprint/name pair upon success,
'missing-key and a fingerprint if the key could not be found, and
'invalid-signature with a fingerprint if the signature is invalid.
KEY-DOWNLOAD specifies a download policy for missing OpenPGP keys; allowed
values: 'always', 'never', and 'interactive' (default). Return a
fingerprint/user name pair on success and #f otherwise."
(let ((status (gnupg-verify sig file)))
(match (gnupg-status-good-signature? status)
((fingerprint . user)
(values 'valid-signature (cons fingerprint user)))
(#f
(let ((missing (gnupg-status-missing-key? status)))
(define (download-and-try-again)
;; Download the missing key and try again.
(if (gnupg-receive-keys missing #:server server #:keyring keyring)
(match (gnupg-status-good-signature?
(gnupg-verify sig file keyring))
(#f
(values 'invalid-signature missing))
((fingerprint . user)
(values 'valid-signature
(cons fingerprint user))))
(values 'missing-key missing)))
(define (receive?)
(let ((answer
(begin
(format #t (G_ "Would you like to add this key \
to keyring '~a'?~%")
keyring)
(read-line))))
(string-match (locale-yes-regexp) answer)))
(case key-download
((never)
(values 'missing-key missing))
((always)
(download-and-try-again))
(else
(if (receive?)
(download-and-try-again)
(values 'missing-key missing)))))))))
;;; gnupg.scm ends here
|