From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.devel,gmane.emacs.pretest.bugs Subject: Re: creating backups in temporary directories Date: Sun, 09 Sep 2007 22:27:30 +0200 Message-ID: References: <85sl5q5vy6.fsf@lola.goethe.zz> <87y7fii7bz.fsf@gmx.de> <85odgbobf0.fsf@lola.goethe.zz> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: sea.gmane.org 1189372265 8509 80.91.229.12 (9 Sep 2007 21:11:05 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Sun, 9 Sep 2007 21:11:05 +0000 (UTC) Cc: emacs-pretest-bug@gnu.org, christopher.ian.moore@gmail.com, svenjoac@gmx.de, Stefan Monnier , rms@gnu.org To: David Kastrup Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Sep 10 07:10:51 2007 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1IUas9-0003kF-Ro for ged-emacs-devel@m.gmane.org; Mon, 10 Sep 2007 06:27:42 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1IUTNi-00073E-3k for ged-emacs-devel@m.gmane.org; Sun, 09 Sep 2007 16:27:46 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1IUTNe-00072z-3f for emacs-devel@gnu.org; Sun, 09 Sep 2007 16:27:42 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1IUTNb-00072n-OM for emacs-devel@gnu.org; Sun, 09 Sep 2007 16:27:40 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1IUTNb-00072k-Hy for emacs-devel@gnu.org; Sun, 09 Sep 2007 16:27:39 -0400 Original-Received: from fencepost.gnu.org ([140.186.70.10]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1IUTNb-0006jl-9r for emacs-devel@gnu.org; Sun, 09 Sep 2007 16:27:39 -0400 Original-Received: from monty-python.gnu.org ([199.232.76.173]) by fencepost.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1IUTNF-0003vh-Ap for emacs-pretest-bug@gnu.org; Sun, 09 Sep 2007 16:27:17 -0400 Original-Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1IUTNX-0006jV-OK for emacs-pretest-bug@gnu.org; Sun, 09 Sep 2007 16:27:39 -0400 Original-Received: from cantor2.suse.de ([195.135.220.15] helo=mx2.suse.de) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1IUTNU-0006j6-GG; Sun, 09 Sep 2007 16:27:32 -0400 Original-Received: from Relay1.suse.de (mail2.suse.de [195.135.221.8]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id BCD6722AE9; Sun, 9 Sep 2007 22:27:30 +0200 (CEST) X-Yow: I need "RONDO". In-Reply-To: <85odgbobf0.fsf@lola.goethe.zz> (David Kastrup's message of "Sun\, 09 Sep 2007 22\:01\:55 +0200") User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.1 (gnu/linux) X-Detected-Kernel: Linux 2.4-2.6 X-Detected-Kernel: Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:78348 gmane.emacs.pretest.bugs:19796 Archived-At: David Kastrup writes: > Stefan Monnier writes: > >> In a directory with mode 777, that's true: everything is dangerous. >> But in a directory with mode 1777 when you open a file that *you* own, >> nobody else can remove it or rename it, so normally nobody can replace= it >> with a symlink. Emacs creates the problem when it moves /tmp/foo to >> /tmp/foo~ at which point /tmp/foo is free for an attacker to take. > > Well, the alternative is to make a hard link of /tmp/foo to /tmp/foo~, > then creat /tmp/foo over it and fill it with contents without > reopening. > > That should close the time window for an attack. You have to unlink the file first, so the window remains. Andreas. --=20 Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux Products GmbH, Maxfeldstra=DFe 5, 90409 N=FCrnberg, Germany PGP key fingerprint =3D 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED= 5 "And now for something completely different."