Re: [PATCH v6 0/8] IMA: support for measuring kernel integrity critical data

From: Pavel Machek <pavel@ucw.cz>
To: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: zohar@linux.ibm.com, stephen.smalley.work@gmail.com,
	casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com,
	gmazyland@gmail.com, paul@paul-moore.com,
	tyhicks@linux.microsoft.com, sashal@kernel.org,
	jmorris@namei.org, nramas@linux.microsoft.com,
	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 v6 0/8] IMA: support for measuring kernel integrity critical data
Date: Sun, 22 Nov 2020 22:00:31 +0100	[thread overview]
Message-ID: <20201122210031.GA26756@amd> (raw)
In-Reply-To: <aadf6e35-39bc-74d4-6ca3-d708860738a5@linux.microsoft.com>

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Hi!

> >How is it supposed to be useful?
> >
> >I'm pretty sure there are critical data that are not measured by
> >proposed module... and that are written under normal circumstances.
> >
> The goal of this series is to introduce the IMA hook
> measure_critical_data() and the necessary policies to use it; and
> illustrate that use with one example (SELinux). It is not scalable to
> identify and update all the critical data sources to use the proposed
> module at once.
> 
> A piecemeal approach to add more critical data measurement in subsequent
> patches would be easy to implement and review.

Basically every other data structure in kernel is "critical" by your
definition, and you can't really measure them all; some of them change
rather often. Going piecemeal does not really help here.

Example of critical data structure: page table entries for process I
own.

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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