linux-kernel - Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always

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Date:	Tue, 17 Jan 2012 19:12:41 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Will Drewry <wad@...omium.org>
Cc:	Andrew Lutomirski <luto@....edu>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jamie Lokier <jamie@...reable.org>,
	linux-kernel@...r.kernel.org, keescook@...omium.org,
	john.johansen@...onical.com, serge.hallyn@...onical.com,
	coreyb@...ux.vnet.ibm.com, pmoore@...hat.com, eparis@...hat.com,
	djm@...drot.org, segoon@...nwall.com, rostedt@...dmis.org,
	jmorris@...ei.org, scarybeasts@...il.com, avi@...hat.com,
	penberg@...helsinki.fi, viro@...iv.linux.org.uk, mingo@...e.hu,
	akpm@...ux-foundation.org, khilman@...com, borislav.petkov@....com,
	amwang@...hat.com, oleg@...hat.com, ak@...ux.intel.com,
	eric.dumazet@...il.com, gregkh@...e.de, dhowells@...hat.com,
	daniel.lezcano@...e.fr, linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org, olofj@...omium.org,
	mhalcrow@...gle.com, dlaor@...hat.com, corbet@....net,
	alan@...rguk.ukuu.org.uk
Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch

Will Drewry <wad@...omium.org> writes:

> One consideration could be to add do_exit()s at known DAC transitions
> (set*id, fcaps). I don't know if that'd be wise, but it would remove
> some described ambiguity.  The same could be done with exec when the
> (e)uid/gid/fcaps change.  However, none of that helps with the opaque
> LSM data, so that'd have to be left up to the LSMs and the LSM_* flag
> you've added.

I went through and audited userspace recently and I could not find
anything that did not handle setuid failing.  It looks like kernel
developers are not the only ones who learned from the
sendmail/capabilities problem.

Eric


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