linux-kernel - Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary

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Message-ID: <20130116215341.GA4222@redhat.com>
Date:	Wed, 16 Jan 2013 16:53:41 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, pjones@...hat.com, hpa@...or.com,
	dhowells@...hat.com, jwboyer@...hat.com,
	Dmitry Kasatkin <dmitry.kasatkin@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary

On Wed, Jan 16, 2013 at 02:24:50PM -0500, Mimi Zohar wrote:
[..]
> > > Sorry, this is out of scope for IMA.  Dmitry has looked into this, but
> > > I'm not sure where it stands at the moment.
> > 
> > Ok, so that's one reason that why I wrote these patcehs. IMA currently
> > is not doing following things to make sure address space of signed images
> > is not modified by others.
> > 
> > - Protecting against modifications to pages on swap.
> > - Protecting against modifications by ptrace.
> > - Protecting against modifications which bypassed filesystem and directly
> >   wrote to the block.
> > 
> > Locking down all the pages of signed binaries in memory hopefully should
> > solve above problems.
> 
> Signing and verifying ELF executables goes back a long time ~2003/4,
> from a number of esteemed kernel developers, including Greg-KH and Serge
> Hallyn.
> 
> IMA-appraisal isn't limited to appraising a single type of file, but is
> a generic mechanism for appraising all files.  If there are issues that
> aren't being addressed, then by all means, please help by addressing
> them.  Duplicating a large portion of the code is not productive.

So do you have ideas on how to address above mentioned issues. Do they
fit into the realm of IMA/EVM or I just need to write separate code (which
I have already done).

With above issues, IMA stuff for executable files sounds incomplete.

Thanks
Vivek
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