linux-kernel - Re: [PATCH v5 03/21] evm: re-release

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Date:	Fri, 20 May 2011 13:12:39 +0200
From:	Harald Hoyer <harald.hoyer@...il.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
CC:	"Serge E. Hallyn" <serge@...lyn.com>,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	James Morris <jmorris@...ei.org>,
	David Safford <safford@...son.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <greg@...ah.com>,
	Dmitry Kasatkin <dmitry.kasatkin@...ia.com>,
	Mimi Zohar <zohar@...ibm.com>
Subject: Re: [PATCH v5 03/21] evm: re-release

Am 20.05.2011 00:49, schrieb Mimi Zohar:
> On Thu, 2011-05-19 at 01:05 -0500, Serge E. Hallyn wrote: 
>> Quoting Mimi Zohar (zohar@...ux.vnet.ibm.com):
>>> EVM protects a file's security extended attributes(xattrs) against integrity
>>> attacks.  This patchset provides the framework and an initial method.  The
>>> initial method maintains an HMAC-sha1 value across the security extended
>>> attributes, storing the HMAC value as the extended attribute 'security.evm'.
>>> Other methods of validating the integrity of a file's metadata will be posted
>>> separately (eg. EVM-digital-signatures).
>>>
>>> While this patchset does authenticate the security xattrs, and
>>> cryptographically binds them to the inode, coming extensions will bind other
>>> directory and inode metadata for more complete protection.  To help simplify
>>> the review and upstreaming process, each extension will be posted separately
>>> (eg. IMA-appraisal, IMA-appraisal-directory).  For a general overview of the
>>> proposed Linux integrity subsystem, refer to Dave Safford's whitepaper:
>>> http://downloads.sf.net/project/linux-ima/linux-ima/Integrity_overview.pdf.
>>>
>>> EVM depends on the Kernel Key Retention System to provide it with a
>>> trusted/encrypted key for the HMAC-sha1 operation. The key is loaded onto the
>>> root's keyring using keyctl.  Until EVM receives notification that the key has
>>> been successfully loaded onto the keyring (echo 1 > <securityfs>/evm), EVM can
>>> not create or validate the 'security.evm' xattr, but returns INTEGRITY_UNKNOWN.
>>> Loading the key and signaling EVM should be done as early as possible. Normally
>>> this is done in the initramfs, which has already been measured as part of the
>>> trusted boot.  For more information on creating and loading existing
>>> trusted/encrypted keys, refer to Documentation/keys-trusted-encrypted.txt.  A
>>> sample dracut patch, which loads the trusted/encrypted key and enables EVM, is
>>> available from http://linu-ima.sourceforge.net/#EVM.
>>
>> That should read http://linux-ima.sourceforge.net/#EVM.
> 
> Thanks for catching that.

The dracut patch, could easily turned into a separate dracut module with its own
files, without patching. Somebody did not understand the modular nature of
dracut. While you are at it, I happily integrate that module in upstream, if you
submit it to the initramfs mailing list.
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