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Subject: Re:
From:   Roberto Sassu <roberto.sassu@huawei.com>
To:     Mimi Zohar <zohar@linux.ibm.com>,
        Prakhar Srivastava <prsriva02@gmail.com>,
        <linux-integrity@vger.kernel.org>,
        <linux-security-module@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <mjg59@google.com>, <vgoyal@redhat.com>
References: <20190521000645.16227-1-prsriva02@gmail.com>
 <20190521000645.16227-3-prsriva02@gmail.com>
 <1558710722.3977.68.camel@linux.ibm.com>
 <a7acac28-156e-80d1-b759-cb0c59f73169@huawei.com>
Message-ID: <cb0eb785-9050-738e-c1bf-8e769fe096fa@huawei.com>
Date:   Fri, 24 May 2019 17:47:05 +0200
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On 5/24/2019 5:42 PM, Roberto Sassu wrote:
> On 5/24/2019 5:12 PM, Mimi Zohar wrote:
>> On Mon, 2019-05-20 at 17:06 -0700, Prakhar Srivastava wrote:
>>> A buffer(cmdline args) measured into ima cannot be appraised
>>> without already being aware of the buffer contents.Since we
>>> don't know what cmdline args will be passed (or need to validate
>>> what was passed) it is not possible to appraise it.
>>>
>>> Since hashs are non reversible the raw buffer is needed to
>>> recompute the hash.
>>> To regenrate the hash of the buffer and appraise the same
>>> the contents of the buffer need to be available.
>>>
>>> A new template field buf is added to the existing ima template
>>> fields, which can be used to store/read the buffer itself.
>>> Two new fields are added to the ima_event_data to carry the
>>> buf and buf_len whenever necessary.
>>>
>>> Updated the process_buffer_measurement call to add the buf
>>> to the ima_event_data.
>>> process_buffer_measurement added in "Add a new ima hook
>>> ima_kexec_cmdline to measure cmdline args"
>>>
>>> - Add a new template field 'buf' to be used to store/read
>>> the buffer data.
>>> - Added two new fields to ima_event_data to hold the buf and
>>> buf_len [Suggested by Roberto]
>>> -Updated process_buffer_meaurement to add the buffer to
>>> ima_event_data
>>
>> This patch description can be written more concisely.
>>
>> Patch 1/3 in this series introduces measuring the kexec boot command
>> line.  This patch defines a new template field for storing the kexec
>> boot command line in the measurement list in order for a remote
>> attestation server to verify.
>>
>> As mentioned, the first patch description should include a shell
>> command for verifying the digest in the kexec boot command line
>> measurement list record against /proc/cmdline.  This patch description
>> should include a shell command showing how to verify the digest based
>> on the new field.  Should the new field in the ascii measurement list
>> be displayed as a string, not hex?
> 
> We should define a new type. If the type is DATA_FMT_STRING, spaces are
> replaced with '_'.

Or better. Leave it as hex, otherwise there would be a parsing problem
if there are spaces in the data for a field.

Roberto

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