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authorLeo Famulari <leo@famulari.name>2016-05-28 13:41:21 -0400
committerLeo Famulari <leo@famulari.name>2016-05-28 19:59:31 -0400
commita535e1222665f3fe5e195573649b7000e8bc9d34 (patch)
tree26fe3d12e415f68b01af9a5e89c6451f0d316be5
parent922fe075d1e4ee7d68e1f56322c82985a953c9e4 (diff)
downloadpatches-a535e1222665f3fe5e195573649b7000e8bc9d34.tar
patches-a535e1222665f3fe5e195573649b7000e8bc9d34.tar.gz
services: Add urandom-seed-service.
Fixes <http://bugs.gnu.org/23605>. * gnu/services/base.scm (urandom-seed-service): New procedure. (%random-seed-file, urandom-seed-service-type): New variables. (%urandom-seed-shepherd-service): New procedure. (%base-services): Call 'urandom-seed-service'. * doc/guix.texi (Base Services): Document it.
-rw-r--r--doc/guix.texi11
-rw-r--r--gnu/services/base.scm62
2 files changed, 72 insertions, 1 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index bb75425a9f..01363c1d13 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7355,6 +7355,17 @@ Return a service that runs the Guix build daemon according to
Run @var{udev}, which populates the @file{/dev} directory dynamically.
@end deffn
+@deffn {Scheme Procedure} urandom-seed-service @var{#f}
+Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
+when rebooting.
+@end deffn
+
+@defvr {Scheme Variable} %random-seed-file
+This is the name of the file where some random bytes are saved by
+@var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
+It defaults to @file{/var/lib/random-seed}.
+@end defvr
+
@deffn {Scheme Procedure} console-keymap-service @var{files} ...
@cindex keyboard layout
Return a service to load console keymaps from @var{files} using
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index 96bf8da02a..a45f219643 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -3,6 +3,7 @@
;;; Copyright © 2015, 2016 Alex Kost <alezost@gmail.com>
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2015 Sou Bunnbu <iyzsong@gmail.com>
+;;; Copyright © 2016 Leo Famulari <leo@famulari.name>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -93,6 +94,8 @@
gpm-service-type
gpm-service
+ urandom-seed-service
+
%base-services))
;;; Commentary:
@@ -422,6 +425,63 @@ stopped before 'kill' is called."
;;;
+;;; Preserve entropy to seed /dev/urandom on boot.
+;;;
+
+(define %random-seed-file
+ "/var/lib/random-seed")
+
+(define %urandom-seed-activation
+ ;; Activation gexp for the urandom seed
+ #~(begin
+ (use-modules (guix build utils))
+
+ (mkdir-p (dirname #$%random-seed-file))
+ (close-port (open-file #$%random-seed-file "a0b"))
+ (chmod #$%random-seed-file #o600)))
+
+(define (urandom-seed-shepherd-service _)
+ "Return a shepherd service for the /dev/urandom seed."
+ (list (shepherd-service
+ (documentation "Preserve entropy across reboots for /dev/urandom.")
+ (provision '(urandom-seed))
+ (requirement '(user-processes))
+ (start #~(lambda _
+ ;; On boot, write random seed into /dev/urandom.
+ (when (file-exists? #$%random-seed-file)
+ (call-with-input-file #$%random-seed-file
+ (lambda (seed)
+ (call-with-output-file "/dev/urandom"
+ (lambda (urandom)
+ (dump-port seed urandom))))))
+ #t))
+ (stop #~(lambda _
+ ;; During shutdown, write from /dev/urandom into random seed.
+ (let ((buf (make-bytevector 512)))
+ (call-with-input-file "/dev/urandom"
+ (lambda (urandom)
+ (get-bytevector-n! urandom buf 0 512)
+ (call-with-output-file #$%random-seed-file
+ (lambda (seed)
+ (put-bytevector seed buf)))
+ #t)))))
+ (modules `((rnrs bytevectors)
+ (rnrs io ports)
+ ,@%default-modules)))))
+
+(define urandom-seed-service-type
+ (service-type (name 'urandom-seed)
+ (extensions
+ (list (service-extension shepherd-root-service-type
+ urandom-seed-shepherd-service)
+ (service-extension activation-service-type
+ (const %urandom-seed-activation))))))
+
+(define (urandom-seed-service)
+ (service urandom-seed-service-type #f))
+
+
+;;;
;;; System-wide environment variables.
;;;
@@ -1200,7 +1260,6 @@ extra rules from the packages listed in @var{rules}."
"Return a service that uses @var{device} as a swap device."
(service swap-service-type device))
-
(define-record-type* <gpm-configuration>
gpm-configuration make-gpm-configuration gpm-configuration?
(gpm gpm-configuration-gpm) ;package
@@ -1281,6 +1340,7 @@ This is the GNU operating system, welcome!\n\n")))
(static-networking-service "lo" "127.0.0.1"
#:provision '(loopback))
(syslog-service)
+ (urandom-seed-service)
(guix-service)
(nscd-service)