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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE glsa SYSTEM "http://www.gentoo.org/dtd/glsa.dtd">
<glsa id="200509-15">
<title>util-linux: umount command validation error</title>
<synopsis>
A command validation error in umount can lead to an escalation of
privileges.
</synopsis>
<product type="ebuild">util-linux</product>
<announced>September 20, 2005</announced>
<revised>September 20, 2005: 01</revised>
<bug>105805</bug>
<access>local</access>
<affected>
<package name="sys-apps/util-linux" auto="yes" arch="*">
<unaffected range="ge">2.12q-r3</unaffected>
<vulnerable range="lt">2.12q-r3</vulnerable>
</package>
</affected>
<background>
<p>
util-linux is a suite of useful Linux programs including umount, a
program used to unmount filesystems.
</p>
</background>
<description>
<p>
When a regular user mounts a filesystem, they are subject to
restrictions in the /etc/fstab configuration file. David Watson
discovered that when unmounting a filesystem with the '-r' option, the
read-only bit is set, while other bits, such as nosuid or nodev, are
not set, even if they were previously.
</p>
</description>
<impact type="high">
<p>
An unprivileged user facing nosuid or nodev restrictions can
umount -r a filesystem clearing those bits, allowing applications to be
executed suid, or have device nodes interpreted. In the case where the
user can freely modify the contents of the filesystem, privilege
escalation may occur as a custom program may execute with suid
permissions.
</p>
</impact>
<workaround>
<p>
Two workarounds exist, first, the suid bit can be removed from the
umount utility, or users can be restricted from mounting and unmounting
filesystems in /etc/fstab.
</p>
</workaround>
<resolution>
<p>
All util-linux users should upgrade to the latest version:
</p>
<code>
# emerge --sync
# emerge --ask --oneshot --verbose &quot;&gt;=sys-apps/util-linux-2.12q-r3&quot;</code>
</resolution>
<references>
<uri link="http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=2005-2876">CAN-2005-2876</uri>
</references>
<metadata tag="requester" timestamp="Sat, 17 Sep 2005 16:18:46 +0000">
koon
</metadata>
<metadata tag="submitter" timestamp="Mon, 19 Sep 2005 16:52:19 +0000">
r2d2
</metadata>
<metadata tag="bugReady" timestamp="Tue, 20 Sep 2005 14:09:16 +0000">
koon
</metadata>
</glsa>