linux-kernel - Re: RFC: disablenetwork facility. (v4)

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Message-ID: <20091229211139.0732a0c1@lxorguk.ukuu.org.uk>
Date:	Tue, 29 Dec 2009 21:11:39 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	ebiederm@...ssion.com (Eric W. Biederman)
Cc:	Benny Amorsen <benny+usenet@...rsen.dk>,
	Bryan Donlan <bdonlan@...il.com>,
	"Serge E. Hallyn" <serue@...ibm.com>,
	Michael Stone <michael@...top.org>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Andi Kleen <andi@...stfloor.org>, David Lang <david@...g.hm>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Valdis Kletnieks <Valdis.Kletnieks@...edu>,
	Evgeniy Polyakov <zbr@...emap.net>,
	"C. Scott Ananian" <cscott@...ott.net>,
	James Morris <jmorris@...ei.org>,
	Bernie Innocenti <bernie@...ewiz.org>,
	Mark Seaborn <mrs@...hic-beasts.com>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Américo Wang <xiyou.wangcong@...il.com>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Samir Bellabes <sam@...ack.fr>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Pavel Machek <pavel@....cz>, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: RFC: disablenetwork facility. (v4)

> > Execute != read. The executable file may contain secrets which must not
> > be available to the user running the setuid program. If you fail the
> > setuid, the user will be able to ptrace() and then the secret is
> > revealed.
> >
> > It's amazing how many security holes appear from what seems like a very
> > simple request.
> 
> Do we have a security hole in nosuid mount option?
> Can someone write a patch to fix it?

If a setuid app can read a key when its erroneously not set setuid then
the user can read it too.

Anything you can do with ptrace you can do yourself !
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