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Subject: Re: [PATCH v4 00/14] ima: introduce IMA Digest Lists extension
From:   Roberto Sassu <roberto.sassu@huawei.com>
To:     <zohar@linux.ibm.com>, <dmitry.kasatkin@huawei.com>,
        <mjg59@google.com>
CC:     <linux-integrity@vger.kernel.org>,
        <linux-security-module@vger.kernel.org>,
        <linux-fsdevel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <silviu.vlasceanu@huawei.com>
References: <20190614175513.27097-1-roberto.sassu@huawei.com>
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Message-ID: <88d368e6-5b3c-0206-23a0-dc3e0aa385f0@huawei.com>
Date:   Tue, 25 Jun 2019 14:57:45 +0200
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On 6/17/2019 8:56 AM, Roberto Sassu wrote:
> On 6/14/2019 7:54 PM, Roberto Sassu wrote:
>> This patch set introduces a new IMA extension called IMA Digest Lists.
>>
>> At early boot, the extension preloads in kernel memory reference digest
>> values, that can be compared with actual file digests when files are
>> accessed in the system.
>>
>> The extension will open for new possibilities: PCR with predictable 
>> value,
>> that can be used for sealing policies associated to data or TPM keys;
>> appraisal based on reference digests already provided by Linux 
>> distribution
>> vendors in the software packages.
>>
>> The first objective can be achieved because the PCR values does not 
>> depend
>> on which and when files are measured: the extension measures digest lists
>> sequentially and files whose digest is not in the digest list.
>>
>> The second objective can be reached because the extension is able to
>> extract reference measurements from packages (with a user space tool) and
>> use it as a source for appraisal verification as the reference came from
>> the security.ima xattr. This approach will also reduce the overhead as 
>> only
>> one signature is verified for many files (as opposed to one signature for
>> each file with the current implementation).
>>
>> This version of the patch set provides a clear separation between current
>> and new functionality. First, the new functionality must be explicitly
>> enabled from the kernel command line. Second, results of operations
>> performed by the extension can be distinguished from those obtained from
>> the existing code: measurement entries created by the extension have a
>> different PCR; mutable files appraised with the extension have a 
>> different
>> security.ima type.
>>
>> The review of this patch set should start from patch 11 and 12, which
>> modify the IMA-Measure and IMA-Appraise submodules to use digest lists.
>> Patch 1 to 5 are prerequisites. Patch 6 to 10 adds support for digest
>> lists. Finally, patch 13 introduces two new policies to measure/appraise
>> rootfs and patch 14 adds the documentation (including a flow chart to
>> show how IMA has been modified).
>>
>> The user space tools to configure digest lists are available at:
>>
>> https://github.com/euleros/digest-list-tools/releases/tag/v0.3
>>
>> The patch set applies on top of linux-integrity/next-queued-testing
>> (73589972b987).
>>
>> It is necessary to apply also:
>> https://patchwork.kernel.org/cover/10957495/
> 
> Another dependency is:
> 
> https://patchwork.kernel.org/cover/10979341/
> 
> Roberto
I uploaded this patch set and all the required dependencies to:

https://github.com/euleros/linux/releases/tag/ima-digest-lists-v4

It should be easy to test. Let me know if you have questions about the
installation.


Mimi, do you have any thoughts on this version?

Thanks

Roberto

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