From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#37445: 27.0.50; Permission denied after make install Date: Fri, 20 Sep 2019 15:40:59 +0300 Message-ID: <83woe3rvhg.fsf@gnu.org> References: <29b48e65-7e65-7d15-7e7e-08b3cefa26fa@cs.ucla.edu> Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="197865"; mail-complaints-to="usenet@blaine.gmane.org" Cc: 37445@debbugs.gnu.org, tino.calancha@gmail.com To: Paul Eggert Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Fri Sep 20 14:43:09 2019 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iBIFh-000pMr-BM for geb-bug-gnu-emacs@m.gmane.org; Fri, 20 Sep 2019 14:43:09 +0200 Original-Received: from localhost ([::1]:59004 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBIFe-0005T5-QX for geb-bug-gnu-emacs@m.gmane.org; Fri, 20 Sep 2019 08:43:06 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:47727) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBIEf-00059n-Qw for bug-gnu-emacs@gnu.org; Fri, 20 Sep 2019 08:42:07 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iBIEd-00034h-9X for bug-gnu-emacs@gnu.org; Fri, 20 Sep 2019 08:42:05 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:48105) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1iBIEc-00034J-Bu for bug-gnu-emacs@gnu.org; Fri, 20 Sep 2019 08:42:03 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1iBIEc-0003gS-6y for bug-gnu-emacs@gnu.org; Fri, 20 Sep 2019 08:42:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 20 Sep 2019 12:42:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 37445 X-GNU-PR-Package: emacs Original-Received: via spool by 37445-submit@debbugs.gnu.org id=B37445.156898327614088 (code B ref 37445); Fri, 20 Sep 2019 12:42:02 +0000 Original-Received: (at 37445) by debbugs.gnu.org; 20 Sep 2019 12:41:16 +0000 Original-Received: from localhost ([127.0.0.1]:56926 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iBIDr-0003fA-Mp for submit@debbugs.gnu.org; Fri, 20 Sep 2019 08:41:15 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:39098) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iBIDq-0003et-2c for 37445@debbugs.gnu.org; Fri, 20 Sep 2019 08:41:14 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:50852) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1iBIDk-0002Rm-Ad; Fri, 20 Sep 2019 08:41:08 -0400 Original-Received: from [176.228.60.248] (port=3681 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1iBIDi-0002a7-1y; Fri, 20 Sep 2019 08:41:07 -0400 In-reply-to: (message from Paul Eggert on Fri, 20 Sep 2019 02:10:10 -0700) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.51.188.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:166760 Archived-At: > From: Paul Eggert > Date: Fri, 20 Sep 2019 02:10:10 -0700 > Cc: 37445@debbugs.gnu.org > > This glitch suggests that there are more-serious security problems in the > default Emacs install. If source-directory is (say) "/tmp/emacs-build/whatever", > and /tmp/emacs-build is removed after the build, an attacker can provide a bogus > source directory in place of the real one, and this could cause real problems. What kind of problems could accessing such a directory cause? Note that there are also various EMACS* environment variables to which Emacs heeds, they can override the likes of data-directory. > Fedora 30 solves this potential security problem by arranging for the Lisp > variable source-directory to have a value like "/usr/share/emacs/26.2/", which > is a place attackers shouldn't be able to overwrite. > > However, the default Emacs install doesn't do that. It installs the sources into > (say) "/usr/local/share/emacs/27.0.50", but it doesn't arrange for > source-directory to point there; instead, source-directory points to wherever > the sources happened to be when Emacs was built, which could be in /tmp. This > sounds like a configuration error in the default Emacs install, and I plan to > look into why it's unsafe whereas the Fedora Emacs install is safer. If you point source-directory away of where the real sources are, some Help features will cease working. So I don't think we want the Fedora solution. What we want is that sources will be inaccessible in this situation, but APIs such as 'load' and 'require' still work regardless.