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

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Date:	Fri, 27 Feb 2015 12:15:15 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Pavel Machek <pavel@....cz>
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 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.

--Andy

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



-- 
Andy Lutomirski
AMA Capital Management, LLC
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