netdev - Re: RFC: disablenetwork facility. (v4)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 29 Dec 2009 13:29:06 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
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)

Alan Cox <alan@...rguk.ukuu.org.uk> writes:

>> > 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 !

Now that I think about it this is really something completely separate
from setuid.  This is about being able to read the text segment with
ptrace when you on have execute permissions on the file.

I just skimmed through fs/exec.c and we set the undumpable process
flag in that case so ptrace should not work in that case.

So short of a bug in the implementation we have no security hole.

Eric
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html