Re: [PATCH v2 00/15] ima: digest list feature

From: Kees Cook
Date: Thu Nov 16 2017 - 20:09:14 EST

On Tue, Nov 7, 2017 at 8:45 AM, Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote:
> On 11/7/2017 2:37 PM, Mimi Zohar wrote:
>> Normally, the protection of kernel memory is out of scope for IMA.
>> This patch set introduces an in kernel white list, which would be a
>> prime target for attackers looking for ways of by-passing IMA-
>> measurement, IMA-appraisal and IMA-audit. Others might disagree, but
>> from my perspective, this risk is too high.

BTW, which part of the series does the whitelist? I'd agree generally,
though: we don't want to make things writable if they're normally

> It would be much easier for an attacker to just set ima_policy_flag to
> zero.

That's a fair point. I wonder if ima_policy_flag could be marked
__ro_after_init? Most of the writes are from __init sections, but I
haven't looked closely at when ima_update_policy() gets called.


Kees Cook
Pixel Security