linux-kernel - Re: [RFC][Patch 5/5]integrity: IMA as an integrity service provider

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Date:	Tue, 5 Aug 2008 19:35:47 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	david safford <safford@...son.ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, serue@...ux.vnet.ibm.com,
	sailer@...son.ibm.com, zohar@...ibm.com,
	Stephen Smalley <sds@...ho.nsa.gov>,
	CaseySchaufler <casey@...aufler-ca.com>
Subject: Re: [RFC][Patch 5/5]integrity: IMA as an integrity service provider

On Tue 2008-06-24 12:28:55, david safford wrote:
> On Sat, 2008-05-31 at 09:54 +0200, Pavel Machek wrote:
> > On Wed 2008-05-28 01:22:42, Andrew Morton wrote:
> > > On Fri, 23 May 2008 11:05:45 -0400 Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> > > 
> > > > This is a re-release of Integrity Measurement Architecture(IMA) as an
> > > > independent Linunx Integrity Module(LIM) service provider, which implements
> > > > the new LIM must_measure(), collect_measurement(), store_measurement(), and
> > > > display_template() API calls. The store_measurement() call supports two 
> > > > types of data, IMA (i.e. file data) and generic template data.
> > ...
> > ...also, it would be nice to see explanation 'what is this good for'.
> > 
> > Closest explanation I remember was 'it will protect you by making
> > system unbootable if someone stole disk with your /usr filesystem --
> > but not / filesystem -- added some rootkit, and then stealthily
> > returned it'. That seems a) very unlikely scenario and b) probably
> > better solved by encrypting /usr.
> > 							Pavel
> 
> Sorry about this delayed response - we are about to repost for RFC, and
> noticed we missed responding to this.
> 
> You are thinking about a related project, EVM, which HMAC's a file's
> metadata, to protect against off-line attacks, (which admittedly
> many users are not concerned about.)
> 
> This submission, IMA, provides hardware (TPM) based measurement and
> attestation, which measures all files before they are accessed in
> any way (on the inode_permission, bprm and mmap hooks), and
> commits the measurements to the TPM. The TPM can sign these 
> measurement lists, and thus the system can prove to itself and

System can never proof to itself.

> to a third party these measurements in a way that cannot be
> circumvented by malicious or compromised software. IMA is just one
> part of integrity detection, as it does not detect purely in-memory
> attacks, such as worms. 

And proofing to third party is useful for what....? Given that it can
be worked around by modifying files in memory, or by special
hardware...? Disney?

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