Add 'build-aux/git-authenticate.scm'.

* build-aux/git-authenticate.scm: New file.
* Makefile.am (EXTRA_DIST): Add it.
(commit_v1_0_1): New variable.
(authenticate): New target.

2 files changed, 364 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index 6106250b37..7474b7f375 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -553,6 +553,7 @@ EXTRA_DIST +=						\
   build-aux/check-final-inputs-self-contained.scm	\
   build-aux/compile-as-derivation.scm			\
   build-aux/generate-authors.scm			\
+  build-aux/git-authenticate.scm			\
   build-aux/test-driver.scm				\
   build-aux/update-guix-package.scm			\
   build-aux/update-NEWS.scm				\
@@ -615,6 +616,18 @@ $(guix_install_go_files): install-nobase_dist_guilemoduleDATA
 install-data-hook:
 	touch "$(DESTDIR)$(guileobjectdir)/guix/config.go"
 
+# Commit corresponding to the 'v1.0.1' tag.
+commit_v1_0_1 = d68de958b60426798ed62797ff7c96c327a672ac
+
+# Authenticate the current Git checkout by checking signatures on every commit
+# starting from $(commit_v1_0_1).
+authenticate:
+	$(AM_V_at)echo "Authenticating Git checkout..." ;	\
+	"$(top_builddir)/pre-inst-env" $(GUILE)			\
+	  --no-auto-compile -e git-authenticate			\
+	  "$(top_srcdir)/build-aux/git-authenticate.scm"	\
+	  "$(commit_v1_0_1)"
+
 # Assuming Guix is already installed and the daemon is up and running, this
 # rule builds from $(srcdir), creating and building derivations.
 as-derivation:
@@ -865,7 +878,7 @@ cuirass-jobs.scm: $(GOBJECTS)
 .PHONY: gen-ChangeLog gen-AUTHORS gen-tarball-version
 .PHONY: assert-no-store-file-names assert-binaries-available
 .PHONY: assert-final-inputs-self-contained
-.PHONY: clean-go make-go as-derivation
+.PHONY: clean-go make-go as-derivation authenticate
 .PHONY: update-guix-package update-NEWS release
 
 # Downloading up-to-date PO files.
diff --git a/build-aux/git-authenticate.scm b/build-aux/git-authenticate.scm
new file mode 100644
index 0000000000..dd7029d438
--- /dev/null
+++ b/build-aux/git-authenticate.scm
@@ -0,0 +1,350 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2019 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/>.
+
+;;;
+;;; Authenticate a range of commits.
+;;;
+
+(use-modules (git)
+             (guix git)
+             (guix gnupg)
+             (guix utils)
+             (guix i18n)
+             (guix progress)
+             (srfi srfi-1)
+             (srfi srfi-11)
+             (srfi srfi-26)
+             (srfi srfi-34)
+             (srfi srfi-35)
+             (ice-9 match)
+             (ice-9 format))
+
+
+(define %committers
+  ;; List of committers.  These are the user names found on
+  ;; <https://savannah.gnu.org/project/memberlist.php?group=guix> along with
+  ;; the fingerprint of the signing (sub)key.
+  ;;
+  ;; TODO: Replace this statically-defined list by an in-repo list.
+  '(("andreas"
+     "AD17 A21E F8AE D8F1 CC02  DBD9 F7D5 C9BF 765C 61E3")
+    ("ajgrf"
+     "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5")
+    ("alexvong1995"
+     "306F CB8F 2C01 C25D 29D3  0556 61EF 502E F602 52F2")
+    ("alezost"
+     "4FB9 9F49 2B12 A365 7997  E664 8246 0C08 2A0E E98F")
+    ("ambrevar"
+     "50F3 3E2E 5B0C 3D90 0424  ABE8 9BDC F497 A4BB CC7F")
+    ("apteryx"
+     "27D5 86A4 F890 0854 329F  F09F 1260 E464 82E6 3562")
+    ("arunisaac"
+     "7F73 0343 F2F0 9F3C 77BF  79D3 2E25 EE8B 6180 2BB3")
+    ("atheia"
+     "3B12 9196 AE30 0C3C 0E90  A26F A715 5567 3271 9948")
+    ("bavier"
+     ;; primary: "34FF 38BC D151 25A6 E340  A0B5 3453 2F9F AFCA 8B8E"
+     "A0C5 E352 2EF8 EF5C 64CD  B7F0 FD73 CAC7 19D3 2566")
+    ("beffa"
+     "3774 8024 880F D3FF DCA2  C9AB 5893 6E0E 2F1B 5A4C")
+    ("benwoodcroft"
+     "BCF8 F737 2CED 080A 67EB  592D 2A6A D9F4 AAC2 0DF6")
+    ("biscuolo"
+     "45CC 63B8 5258 C9D5 5F34  B239 D37D 0EA7 CECC 3912")
+    ("boskovits"
+     "7988 3B9F 7D6A 4DBF 3719  0367 2506 A96C CF63 0B21")
+    ("brettgilio"
+     "DFC0 C7F7 9EE6 0CA7 AE55  5E19 6722 43C4 A03F 0EEE")
+    ("carl"
+     ;; primary: "0401 7A2A 6D9A 0CCD C81D  8EC2 96AB 007F 1A7E D999"
+     "09CD D25B 5244 A376 78F6  EEA8 0CC5 2153 1979 91A5")
+    ("cbaines"
+     "3E89 EEE7 458E 720D 9754  E0B2 5E28 A33B 0B84 F577")
+    ("civodul"
+     "3CE4 6455 8A84 FDC6 9DB4  0CFB 090B 1199 3D9A EBB5")
+    ("cwebber"
+     "510A 8628 E2A7 7678 8F8C  709C 4BC0 2592 5FF8 F4D3")
+    ("dannym"
+     ;; primary: "295A F991 6F46 F8A1 34B0  29DA 8086 3842 F0FE D83B"
+     "76CE C6B1 7274 B465 C02D  B3D9 E71A 3554 2C30 BAA5")
+    ("davexunit"
+     "B3C0 DB4D AD73 BA5D 285E  19AE 5143 0234 CEFD 87C3")
+    ("davexunit (2nd)"                            ;FIXME: to be confirmed!
+     "8CCB A7F5 52B9 CBEA E1FB  2915 8328 C747 0FF1 D807")
+    ("dvc"
+     "6909 6DFD D702 8BED ACC5  884B C5E0 51C7 9C0B ECDB")
+    ("dvc (old)"
+     "5F43 B681 0437 2F4B A898  A64B 33B9 E9FD E28D 2C23")
+    ("efraim"
+     "A28B F40C 3E55 1372 662D  14F7 41AA E7DC CA3D 8351")
+    ("efraim (old)"
+     "9157 41FE B22F A4E3 3B6E  8F8D F4C1 D391 7EAC EE93")
+    ("hoebjo"
+     "2219 43F4 9E9F 276F 9499  3382 BF28 6CB6 593E 5FFD")
+    ("htgoebel"
+     "B943 509D 633E 80DD 27FC  4EED 634A 8DFF D3F6 31DF")
+    ("ipetkov"
+     "7440 26BA 7CA3 C668 E940  1D53 0B43 1E98 3705 6942")
+    ("iyzsong"
+     ;; primary: "66A5 6D9C 9A98 BE7F 719A  B401 2652 5665 AE72 7D37"
+     "0325 78A6 8298 94E7 2AA2  66F5 D415 BF25 3B51 5976")
+
+    ;; https://lists.gnu.org/archive/html/guix-devel/2018-04/msg00229.html
+    ("janneke (old)"
+     "DB34 CB51 D25C 9408 156F  CDD6 A12F 8797 8D70 1B99")
+    ("janneke"
+     "1A85 8392 E331 EAFD B8C2  7FFB F3C1 A0D9 C1D6 5273")
+
+    ("jlicht"
+     ;; primary: "1BA4 08C5 8BF2 0EA7 3179  635A 865D C0A3 DED9 B5D0"
+     "E31D 9DDE EBA5 4A14 8A20  4550 DA45 97F9 47B4 1025")
+    ("jmd"
+     "8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3")
+    ("kkebreau"
+     "83B6 703A DCCA 3B69 4BCE  2DA6 E6A5 EE3C 1946 7A0D")
+    ("leungbk"
+     "45E5 75FA 53EA 8BD6 1BCE  0B4E 3ADC 75F0 13D6 78F9")
+    ("lfam"
+     ;; primary: "4F71 6F9A 8FA2 C80E F1B5  E1BA 5E35 F231 DE1A C5E0"
+     "B051 5948 F1E7 D3C1 B980  38A0 2646 FA30 BACA 7F08")
+    ("lsl88"
+     "2AE3 1395 932B E642 FC0E  D99C 9BED 6EDA 32E5 B0BC")
+    ("marusich"
+     "CBF5 9755 CBE7 E7EF EF18  3FB1 DD40 9A15 D822 469D")
+    ("mbakke"
+     "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")
+    ("mhw"
+     "D919 0965 CE03 199E AF28  B3BE 7CEF 2984 7562 C516")
+    ("mothacehe"
+     "4008 6A7E 0252 9B60 31FB  8607 8354 7635 3176 9CA6")
+    ("mthl"
+     "F2A3 8D7E EB2B 6640 5761  070D 0ADE E100 9460 4D37")
+    ("nckx"
+     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
+     "7E8F AED0 0944 78EF 72E6  4D16 D889 B0F0 18C5 493C")
+    ("nckx (2nd)"
+     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
+     "F5DA 2032 4B87 3D0B 7A38  7672 0DB0 FF88 4F55 6D79")
+    ("ngz"
+     "ED0E F1C8 E126 BA83 1B48  5FE9 DA00 B4F0 48E9 2F2D")
+    ("pelzflorian"
+     "CEF4 CB91 4856 BA38 0A20  A7E2 3008 88CB 39C6 3817")
+    ("pgarlick"
+     ;; primary: "B68B DF22 73F9 DA0E 63C1  8A32 515B F416 9242 D600"
+     "C699 ED09 E51B CE89 FD1D  A078 AAC7 E891 896B 568A")
+    ("phant0mas"
+     "3A86 380E 58A8 B942 8D39  60E1 327C 1EF3 8DF5 4C32")
+    ("reepca"
+     "74D6 A930 F44B 9B84 9EA5  5606 C166 AA49 5F7F 189C")
+    ("rekado"
+     "BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC")
+    ("rhelling"
+     "0154 E1B9 1CC9 D9EF 7764  8DE7 F3A7 27DB 44FC CA36")
+    ("roelj"
+     "17CB 2812 EB63 3DFF 2C7F  0452 C3EC 1DCA 8430 72E1")
+    ("roptat"
+     "B5FA E628 5B41 3728 B2A0  FAED 4311 1F45 2008 6A0C")
+    ("samplet"
+     ;; primary: "D6B0 C593 DA8C 5EDC A44C  7A58 C336 91F7 1188 B004"
+     "A02C 2D82 0EF4 B25B A6B5  1D90 2AC6 A5EC 1C35 7C59")
+    ("sleep_walker"
+     "77DD AD2D 97F5 31BB C0F3  C7FD DFB5 EB09 AA62 5423")
+    ("snape"
+     "F494 72F4 7A59 00D5 C235  F212 89F9 6D48 08F3 59C7")
+    ("snape"
+     "F494 72F4 7A59 00D5 C235  F212 89F9 6D48 08F3 59C7")
+    ("steap"
+     "4E26 CCE9 578E 0828 9855  BDD4 1C79 95D2 D5A3 8336")
+    ("taylanub"
+     "9ADE 9ECF 2B19 C180 9C99  5CEA A1F4 CFCC 5283 6BAC")
+
+    ;; https://lists.gnu.org/archive/html/guix-devel/2017-03/msg00826.html
+    ("thomasd"
+     "1DD1 681F E285 E07F 11DC  0C59 2E15 A6BC D77D 54FD")
+    ("thomasd (old)"
+     "A5C5 92EA 606E 7106 A6A3  BC08 98B2 1575 91E1 2B08")
+
+    ("toothbrush"
+     "D712 1D73 A40A 7264 9E43  ED7D F284 6B1A 0D32 C442")
+    ("vagrantc"
+     "6580 7361 3BFC C5C7 E2E4  5D45 DC51 8FC8 7F97 16AA")
+    ("wigust"
+     ;; primary: "C955 CC5D C048 7FB1 7966  40A9 199A F6A3 67E9 4ABB"
+     "7238 7123 8EAC EB63 4548  5857 167F 8EA5 001A FA9C")
+    ("wingo"
+     "FF47 8FB2 64DE 32EC 2967  25A3 DDC0 F535 8812 F8F2")))
+
+(define %authorized-signing-keys
+  ;; Fingerprint of authorized signing keys.
+  (map (match-lambda
+         ((name fingerprint)
+          (string-filter char-set:graphic fingerprint)))
+       %committers))
+
+(define %commits-with-bad-signature
+  ;; Commits with a known-bad signature.
+  '("6a34f4ccc8a5d4a48e25ad3c9c512f8634928b91"))  ;2016-12-29
+
+(define %unsigned-commits
+  ;; Commits lacking a signature.
+  '())
+
+(define-syntax-rule (with-temporary-files file1 file2 exp ...)
+  (call-with-temporary-output-file
+   (lambda (file1 port1)
+     (call-with-temporary-output-file
+      (lambda (file2 port2)
+        exp ...)))))
+
+(define (commit-signing-key repo commit-id)
+  "Return the OpenPGP key ID that signed COMMIT-ID (an OID).  Raise an
+exception if the commit is unsigned or has an invalid signature."
+  (let-values (((signature signed-data)
+                (catch 'git-error
+                  (lambda ()
+                    (commit-extract-signature repo commit-id))
+                  (lambda _
+                    (values #f #f)))))
+    (if (not signature)
+        (raise (condition
+                (&message
+                 (message (format #f (G_ "commit ~a lacks a signature")
+                                  commit-id)))))
+        (begin
+          (with-fluids ((%default-port-encoding "UTF-8"))
+            (with-temporary-files data-file signature-file
+              (call-with-output-file data-file
+                (cut display signed-data <>))
+              (call-with-output-file signature-file
+                (cut display signature <>))
+
+              (let-values (((status data)
+                            (with-error-to-port (%make-void-port "w")
+                              (lambda ()
+                                (gnupg-verify* signature-file data-file
+                                               #:key-download 'always)))))
+                (match status
+                  ('invalid-signature
+                   ;; There's a signature but it's invalid.
+                   (raise (condition
+                           (&message
+                            (message (format #f (G_ "signature verification failed \
+for commit ~a")
+                                             (oid->string commit-id)))))))
+                  ('missing-key
+                   (raise (condition
+                           (&message
+                            (message (format #f (G_ "could not authenticate \
+commit ~a: key ~a is missing")
+                                             (oid->string commit-id)
+                                             data))))))
+                  ('valid-signature
+                   (match data
+                     ((fingerprint . user)
+                      fingerprint)))))))))))
+
+(define (authenticate-commit repository commit)
+  "Authenticate COMMIT from REPOSITORY and return the signing key fingerprint.
+Raise an error when authentication fails."
+  (define id
+    (commit-id commit))
+
+  (define signing-key
+    (commit-signing-key repository id))
+
+  (unless (member signing-key %authorized-signing-keys)
+    (raise (condition
+            (&message
+             (message (format #f (G_ "commit ~a not signed by an authorized \
+key: ~a")
+                              (oid->string id) signing-key))))))
+
+  signing-key)
+
+(define* (authenticate-commits repository commits
+                               #:key (report-progress (const #t)))
+  "Authenticate COMMITS, a list of commit objects, calling REPORT-PROGRESS for
+each of them.  Return an alist showing the number of occurrences of each key."
+  (parameterize ((current-keyring (string-append (config-directory)
+                                                 "/keyrings/channels/guix.kbx")))
+    (fold (lambda (commit stats)
+            (report-progress)
+            (let ((signer (authenticate-commit repository commit)))
+              (match (assoc signer stats)
+                (#f          (cons `(,signer . 1) stats))
+                ((_ . count) (cons `(,signer . ,(+ count 1))
+                                   (alist-delete signer stats))))))
+          '()
+          commits)))
+
+(define commit-short-id
+  (compose (cut string-take <> 7) oid->string commit-id))
+
+
+;;;
+;;; Entry point.
+;;;
+
+(define (git-authenticate args)
+  (define repository
+    (repository-open "."))
+
+  (let loop ((args args))
+    (match args
+      ((_ start end)
+       (define start-commit
+         (commit-lookup repository (string->oid start)))
+       (define end-commit
+         (commit-lookup repository (string->oid end)))
+
+       (define commits
+         (commit-difference end-commit start-commit))
+
+       (define reporter
+         (progress-reporter/bar (length commits)))
+
+       (format #t (G_ "Authenticating ~a to ~a (~a commits)...~%")
+               (commit-short-id start-commit)
+               (commit-short-id end-commit)
+               (length commits))
+
+       (let ((stats (call-with-progress-reporter reporter
+                      (lambda (report)
+                        (authenticate-commits repository commits
+                                              #:report-progress report)))))
+         (format #t (G_ "Signing statistics:~%"))
+         (for-each (match-lambda
+                     ((signer . count)
+                      (format #t "  ~a ~10d~%" signer count)))
+                   (sort stats
+                         (match-lambda*
+                           (((_ . count1) (_ . count2))
+                            (> count1 count2)))))))
+      ((command start)
+       (let* ((head (repository-head repository))
+              (end  (reference-target head)))
+         (loop (list command start (oid->string end)))))
+      (_
+       (format (current-error-port)
+               (G_ "Usage: git-authenticate START [END]
+
+Authenticate commits START to END or the current head.\n"))))))
+
+;;; Local Variables:
+;;; eval: (put 'with-temporary-files 'scheme-indent-function 2)
+;;; End: