linux-kernel - Re: Possible problem in linux file posix capabilities

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Message-ID: <20080218134443.GA22552@sergelap.austin.ibm.com>
Date:	Mon, 18 Feb 2008 07:44:43 -0600
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Casey Schaufler <casey@...aufler-ca.com>
Cc:	"Serge E. Hallyn" <serue@...ibm.com>, charles.kirsch@...ernet.lu,
	Andrew Morgan <morgan@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	Gerald Combs <gerald@...eshark.org>,
	Gilbert Ramirez <gram@...mni.rice.edu>,
	Guy Harris <guy@...m.mit.edu>
Subject: Re: Possible problem in linux file posix capabilities

Quoting Casey Schaufler (casey@...aufler-ca.com):
> 
> --- "Serge E. Hallyn" <serue@...ibm.com> wrote:
> 
> > ....
> > 
> > Two quick fixes for you right now (apart from the one you've already
> > got :)  would be
> > 
> > 	1. give wireshark cap_kill, by doing something like
> > 
> > 		capset cap_kill=ep /bin/wireshark
> > 
> > 	2. compile a kernel with SECURITY_FILE_CAPABILITIES=n
> > 
> > Andrew, this pretty much was bound to happen...  we need to figure out
> > what our approach here should be.  My preference is still to allow
> > signals when p->uid==current->uid so long as !SECURE_NOROOT.  Then as
> > people start using secure_noroot process trees they at least must know
> > what they're asking for.
> > 
> > An alternative stance is to accept these things as they come up and try
> > to quickly work with the authors of such programs to work around it.  I
> > suppose in a security sense that's the superior way :)  But it also
> > seems likely to lead to most people choosing option 2 above and not
> > bothering to fix the problem.
> 
> I probably just missed it when it went by, but do you have some
> test cases for file capabilities lying about that I might use?

Yup, please download the latest ltp cvs tree (I don't think it's in any
release yet, though I may be wrong) and look under
testcaes/kernel/security/filecaps.  Or just do

	cd ltp
	make && make install && ./runltp -s filecap

-serge
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