From: Xinglu Chen <public@yoctocell.xyz>
To: 48923@debbugs.gnu.org
Cc: Maxime Devos <maximedevos@telenet.be>
Subject: [bug#48923] [PATCH] build: utils: Add ‘call-with-outp
Date: Tue, 08 Jun 2021 17:40:52 +0200 [thread overview]
Message-ID: <23ac66d29119c5395fee0e993ea0fe811beefd91.1623166798.git.public@yoctocell.xyz> (raw)
Using ‘call-with-output-file*’ instead of ‘call-with-output-file’ and ‘chmod’
will prevent secrets from being leaked. See
<https://issues.guix.gnu.org/48872>.
* guix/build/utils.scm (call-with-output-file*): New procedure.
* doc/guix.texi (Build Utilities): Document it.
---
doc/guix.texi | 19 +++++++++++++++++++
guix/build/utils.scm | 10 ++++++++++
2 files changed, 29 insertions(+)
diff --git a/doc/guix.texi b/doc/guix.texi
index 59b4ac11b4..7e15cd9e92 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -8612,6 +8612,25 @@ Be careful about using @code{$} to match the end of a line; by itself it
won't match the terminating newline of a line.
@end deffn
+@deffn {Scheme Procedure} call-with-output-file* @var{file} @var{proc} @
+ [#:perms #o666]
+Open FILE for output, set the file permission bits to @var{perms}, and
+call @code{(PROC port)} with the resulting port.
+
+The advantage of using this procedure compared to something like this
+
+@lisp
+(call-with-output-file "FILE"
+ (lambda (port)
+ (display "top secret" port)))
+(chmod "FILE" #o400)
+@end lisp
+
+is that, with the latter, an unpriviliged user could open @var{file}
+before the permission was changed to @code{#o400}, thus making it
+possible to leak sensitive information.
+@end deffn
+
@subsection File Search
@cindex file, searching
diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index 419c10195b..df960eee84 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
@@ -5,6 +5,7 @@
;;; Copyright © 2015, 2018 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
+;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -66,6 +67,7 @@
file-name-predicate
find-files
false-if-file-not-found
+ call-with-output-file*
search-path-as-list
set-path-environment-variable
@@ -448,6 +450,14 @@ also be included. If FAIL-ON-ERROR? is true, raise an exception upon error."
#f
(apply throw args)))))
+;; Prevent secrets from leaking, see <https://issues.guix.gnu.org/48872>
+(define* (call-with-output-file* file proc #:key (perms #o666))
+ "FILE should be string containg the path to a file, PROC should be a procedure
+that accepts the port as an argument, and PERMS should be the permission bits
+of the file, the default is 666."
+ (let ((port (open file (bitwise-ior O_WRONLY O_CREAT) perms)))
+ (call-with-port port proc)))
+
\f
;;;
;;; Search paths.
base-commit: 503c2039a280dd52a751a6852b4157fccd1b4195
--
2.32.0
next reply other threads:[~2021-06-08 15:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-08 15:40 Xinglu Chen [this message]
2021-06-08 16:04 ` [bug#48923] [PATCH] build: utils: Add ‘call-with-outp Maxime Devos
2021-06-08 17:36 ` Xinglu Chen
2021-06-08 17:45 ` Maxime Devos
2021-06-08 18:04 ` Xinglu Chen
2021-06-08 18:30 ` [bug#48923] [PATCH v2] activation: Add ‘call-with-output-file*’ procedure Xinglu Chen
2021-08-04 8:25 ` Xinglu Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=23ac66d29119c5395fee0e993ea0fe811beefd91.1623166798.git.public@yoctocell.xyz \
--to=public@yoctocell.xyz \
--cc=48923@debbugs.gnu.org \
--cc=maximedevos@telenet.be \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/guix.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.