linux-kernel - Re: [PATCH 2/2] ima: Support appraise_type=imasig

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Date:	Thu, 14 Feb 2013 10:23:39 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	"Kasatkin, Dmitry" <dmitry.kasatkin@...el.com>,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ima: Support appraise_type=imasig_optional

On Thu, Feb 14, 2013 at 07:57:16AM -0500, Mimi Zohar wrote:

[..]
> > Ok, I will cleanup the code to do above. Just wanted to clear up one
> > point. 
> > 
> > Above option will not have any effect on evm behavior? This only impacts
> > IMA appraisal behavior. For example, if security.ima is not present it
> > is fine and file access is allowed. But if EVM is enabled and initialized
> > and EVM does not find security.evm label (INTEGRITY_NOLABEL) or returns
> > INTEGRITY_NOXATTRS, file access should still be denied?
> 
> Can't happen.  evm_verifyxattr() is called from
> ima_appraise_measurement(), only if 'security.ima' exists.

Actually what I meant is following.

Currently in process_measurement(), I will allow access if
ima_appraise_measurement() returns INTEGRITY_NOLABEL.

Now this could mean 2 things.

- security.ima was not present.
- security.ima was there but security.evm was not present.

With appraise_type=optional, I think we would want to allow access in
first case but not the second one. IOW, appraise_type= affects behavior
of IMA and not EVM.

That means we need to introduce new codes.

INTEGRITY_IMA_NOLABEL and INTEGRITY_EVM_NOLABEL to differentiate between
above two cases?

Thanks
Vivek
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