Re: [PATCH v10 8/8] selinux: include a consumer of the new IMA critical data hook

From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
	Paul Moore <paul@paul-moore.com>, Sasha Levin <sashal@kernel.org>
Cc: Tushar Sugandhi <tusharsu@linux.microsoft.com>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com,
	gmazyland@gmail.com, tyhicks@linux.microsoft.com,
	James Morris <jmorris@namei.org>,
	linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, dm-devel@redhat.com
Subject: Re: [PATCH v10 8/8] selinux: include a consumer of the new IMA critical data hook
Date: Thu, 14 Jan 2021 11:21:46 -0800	[thread overview]
Message-ID: <507ebab8-828b-8b44-45be-2dbff3406b72@linux.microsoft.com> (raw)
In-Reply-To: <e883298b-1027-2a58-dcf8-fc940ebc27ff@linux.microsoft.com>

On 1/14/21 9:48 AM, Lakshmi Ramasubramanian wrote:
> On 1/14/21 8:50 AM, Mimi Zohar wrote:
>> On Thu, 2021-01-14 at 11:44 -0500, Mimi Zohar wrote:
>>> [Cc'ing Sasha]
>>>
>>> Hi Lakshmi,
>>>
>>> On Thu, 2021-01-14 at 08:22 -0800, Lakshmi Ramasubramanian wrote:
>>>> On 1/13/21 6:49 PM, Mimi Zohar wrote:
>>>
>>>>>>> Lakshmi is trying to address the situation where an event changes a
>>>>>>> value, but then is restored to the original value.  The original and
>>>>>>> subsequent events are measured, but restoring to the original value
>>>>>>> isn't re-measured.  This isn't any different than when a file is
>>>>>>> modified and then reverted.
>>>>>>>
>>>>>>> Instead of changing the name like this, which doesn't work for 
>>>>>>> files,
>>>>>>> allowing duplicate measurements should be generic, based on policy.
>>>>>>
>>>>>> Perhaps it is just the end of the day and I'm a bit tired, but I just
>>>>>> read all of the above and I have no idea what your current thoughts
>>>>>> are regarding this patch.
>>>>>
>>>>> Other than appending the timestamp, which is a hack, the patch is 
>>>>> fine.
>>>>> Support for re-measuring an event can be upstreamed independently.
>>>>>
>>>>
>>>> Thanks for clarifying the details related to duplicate measurement
>>>> detection and re-measuring.
>>>>
>>>> I will keep the timestamp for the time being, even though its a 
>>>> hack, as
>>>> it helps with re-measuring state changes in SELinux. We will add 
>>>> support
>>>> for "policy driven" re-measurement as a subsequent patch series.
>>>
>>> Once including the timestamp is upstreamed, removing it will be
>>> difficult, especially if different userspace applications are dependent
>>> on it.  Unless everyone is on board that removing the timestamp
>>> wouldn't be considered a regression, it cannot be upstreamed.
>>
>> Feel free to just re-post just this one patch.  Otherwise the patch set
>> looks good.
>>
>> thanks,
>>
> 
> Sounds good Mimi - I will remove the timestamp and re-post the selinux 
> patch.
> 

I have removed the timestamp in the event name and have posted the 
selinux patch alone.

Thanks a lot for reviewing the changes.

  -lakshmi