From: Pavel Machek <pavel@ucw.cz>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: Tushar Sugandhi <tusharsu@linux.microsoft.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: Mon, 23 Nov 2020 18:18:00 +0100 [thread overview]
Message-ID: <20201123171800.GA6407@duo.ucw.cz> (raw)
In-Reply-To: <d82ad1cac36e948c904300548c64244c145589ee.camel@linux.ibm.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.
>
> Agreed, measuring data structures that change is not really applicable.
> However, measuring data structures that once initialized don't change,
> does make sense (similar concept to __ro_after_init). The attestation
> server doesn't need to know anything about the measurement, other than
> more than a single measurement is indicative of a problem.
So, why not simply measure everything that is ro_after_init?
But... I really fail to see how this is useful. It is trivial to
"backdoor" kernel w/o modifying anything that is
ro_after_init. (Example: page tables).
Pavel
--
http://www.livejournal.com/~pavelmachek
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next prev parent reply other threads:[~2020-11-23 17:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 23:26 [PATCH v6 0/8] IMA: support for measuring kernel integrity critical data Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 1/8] IMA: generalize keyring specific measurement constructs Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 2/8] IMA: add support to measure buffer data hash Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 3/8] IMA: define a hook to measure kernel integrity critical data Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 4/8] IMA: add policy rule to measure " Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 5/8] IMA: extend policy to add data sources as a critical data measurement constraint Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 6/8] IMA: add support to critical data hook to limit data sources for measurement Tushar Sugandhi
2020-11-19 23:26 ` [PATCH v6 7/8] IMA: add a built-in policy rule for critical data measurement Tushar Sugandhi
2020-11-20 14:30 ` Mimi Zohar
2020-11-20 23:33 ` Lakshmi Ramasubramanian
2020-11-19 23:26 ` [PATCH v6 8/8] selinux: measure state and hash of the policy using IMA Tushar Sugandhi
2020-11-20 15:49 ` Mimi Zohar
2020-11-20 23:40 ` Lakshmi Ramasubramanian
2020-11-21 2:05 ` James Morris
2020-11-23 19:37 ` Tushar Sugandhi
2020-11-20 12:46 ` [PATCH v6 0/8] IMA: support for measuring kernel integrity critical data Pavel Machek
2020-11-22 20:53 ` Tushar Sugandhi
2020-11-22 21:00 ` Pavel Machek
2020-11-23 13:41 ` Mimi Zohar
2020-11-23 17:18 ` Pavel Machek [this message]
2020-11-23 19:49 ` Mimi Zohar
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