linux-kernel - Re: [capabilities] Allow normal inheritance for a configurable set of capabilities

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Message-ID: <20150227204833.GA18200@amd>
Date:	Fri, 27 Feb 2015 21:48:33 +0100
From:	Pavel Machek <pavel@....cz>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Christoph Lameter <cl@...ux.com>,
	Serge Hallyn <serge.hallyn@...ntu.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Jonathan Corbet <corbet@....net>,
	Aaron Jones <aaronmdjones@...il.com>, Ted Ts'o <tytso@....edu>,
	LSM List <linux-security-module@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...uxfoundation.org>,
	"Andrew G. Morgan" <morgan@...nel.org>
Subject: Re: [capabilities] Allow normal inheritance for a configurable set
 of capabilities

On Fri 2015-02-27 12:15:15, Andy Lutomirski wrote:
> On Thu, Feb 26, 2015 at 4:27 AM, Pavel Machek <pavel@....cz> wrote:
> > On Wed 2015-02-25 17:59:04, Christoph Lameter wrote:
> >> On Wed, 25 Feb 2015, Pavel Machek wrote:
> >>
> >> > One solution is to put capabilities into the elf executable. I believe
> >> > there was patch for that. That means you don't need to add capability
> >> > support into filesystems...
> >>
> >> Ummm... So I can just get any caps by modifying the ELF header?
> >> Looking at the docs No, it just drops caps so binaries must be
> >> setsuid.
> >
> > exactly. Normal apps are not currently allowed to receive
> > capabilities, because they may not be ready for them.
> >
> > So add an elf note marking what capabilities it can deal with.
> > No need for setuid if caller has the capabilities already.
> 
> We'd need extremely broad coverage for this to be useful because of
> shells, pipelines, scripts, etc.  We'd need bash, env, python, etc.

Well.. capabilities for scripts will be "fun" even when you have
proper filesystem support. I'd say that is separate problem... (and
yes, it would have to be solved.)

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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