linux-kernel - Re: LSM conversion to static interface

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Message-ID: <5541.1193307789@turing-police.cc.vt.edu>
Date:	Thu, 25 Oct 2007 06:23:09 -0400
From:	Valdis.Kletnieks@...edu
To:	"Serge E. Hallyn" <serge@...lyn.com>
Cc:	Jan Engelhardt <jengelh@...putergmbh.de>,
	Giacomo Catenazzi <cate@...ian.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andreas Gruenbacher <agruen@...e.de>,
	Thomas Fricaccia <thomas_fricacci@...oo.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	James Morris <jmorris@...ei.org>
Subject: Re: LSM conversion to static interface

On Tue, 23 Oct 2007 10:34:09 CDT, "Serge E. Hallyn" said:

> And he will still be able to *run* the suid binary, but if cap_bound is
> reduced he won't be able to use capabilities taken out of the bounding
> set, multiadm loaded or not.

I am willing to bet that there's still a *lot* of unaudited set[ug]id code
out there that's vulnerable to the same sorts of attacks as the one that
hit Sendmail a few back.  As such, I have to agree with your original
post of the patch that CAP_SYS_ADMIN should be required to lower the set,
as there's just too much danger of an exploit if users can create their
own reduced-set processes.

I'm debating whether we should have a printk if we detect that a removed
capability caused an -EPERM.  Yes, it can be used to spam the logs.  On the
other hand, I as the sysadmin would like to know if it's happening. Looks like
time for a sysctl or something....

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