From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Tue, 25 Aug 2009 17:42:49 +0000 Subject: Re: [security] Race condition in udev Message-Id: <20090825174249.GA13539@kroah.com> List-Id: References: <20090821102407.GA29609@florz.florz.dyndns.org> In-Reply-To: <20090821102407.GA29609@florz.florz.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Tue, Aug 25, 2009 at 07:31:30PM +0200, Florian Zumbiehl wrote: > Assumption: > > /dev/foo is configured to be owned by user root, group users, mode 0646. > The attacker tries to open /dev/foo for writing as a user that's not > root, not a member of the group root, but a member of the group users. > > The Trace: > > action | owner | group | mode | open(O_WRONLY)? > ----------------------------+-------+-------+---------+----------------- > mknod(/dev/foo) | root | root | 0644(?) | no > chmod(/dev/foo,0646) | root | root | 0646 | yes > chown(/dev/foo,root,users) | root | users | 0646 | no Are there any current device nodes that get set to this kind of "odd" permissions with the current udev ruleset? > Could we now take care of the bug? Do you have a proposed patch? thanks, greg k-h