From d7113bb655ff80a868a9e624c913f9d23e6c63ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Mon, 6 Apr 2020 23:50:27 +0200
Subject: [PATCH] services: syslog: Create log files as non-world-readable.

Partly fixes <https://bugs.gnu.org/40405>.
Reported by Diego Nicola Barbato <dnbarbato@posteo.de>.

* gnu/services/base.scm (syslog-service-type): Change 'start' method to
set umask to #o137 before spawning syslogd.
* gnu/tests/base.scm (run-basic-test)["/var/log/messages is not
world-readable"]: New test.
---
 gnu/services/base.scm | 15 +++++++++++----
 gnu/tests/base.scm    |  8 ++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index a0179c0259..f802005e3c 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -1436,10 +1436,17 @@ (define syslog-service-type
       (documentation "Run the syslog daemon (syslogd).")
       (provision '(syslogd))
       (requirement '(user-processes))
-      (start #~(make-forkexec-constructor
-                (list #$(syslog-configuration-syslogd config)
-                      "--rcfile" #$(syslog-configuration-config-file config))
-                #:pid-file "/var/run/syslog.pid"))
+      (start #~(let ((spawn (make-forkexec-constructor
+                             (list #$(syslog-configuration-syslogd config)
+                                   "--rcfile"
+                                   #$(syslog-configuration-config-file config))
+                             #:pid-file "/var/run/syslog.pid")))
+                 (lambda ()
+                   ;; Set the umask such that file permissions are #o640.
+                   (let ((mask (umask #o137))
+                         (pid  (spawn)))
+                     (umask mask)
+                     pid))))
       (stop #~(make-kill-destructor))))))
 
 ;; Snippet adapted from the GNU inetutils manual.
diff --git a/gnu/tests/base.scm b/gnu/tests/base.scm
index 37b83dc7ec..fe63cecbd0 100644
--- a/gnu/tests/base.scm
+++ b/gnu/tests/base.scm
@@ -195,6 +195,14 @@ (define marionette
                      (pk 'services services)
                      '(root #$@(operating-system-shepherd-service-names os)))))
 
+          (test-equal "/var/log/messages is not world-readable"
+            #o640                                ;<https://bugs.gnu.org/40405>
+            (begin
+              (wait-for-file "/var/log/messages" marionette
+                             #:read 'get-u8)
+              (marionette-eval '(stat:perms (lstat "/var/log/messages"))
+                               marionette)))
+
           (test-assert "homes"
             (let ((homes
                    '#$(map user-account-home-directory