linux-kernel - Re: [PATCH v10 0/8] IMA: support for measuring kernel integrity critical data

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Message-ID: <5189c15054885863b1b5cb86a43bec09725d8650.camel@linux.ibm.com>
Date:   Fri, 15 Jan 2021 07:54:42 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Tushar Sugandhi <tusharsu@...ux.microsoft.com>,
        stephen.smalley.work@...il.com, casey@...aufler-ca.com,
        agk@...hat.com, snitzer@...hat.com, gmazyland@...il.com,
        paul@...l-moore.com
Cc:     tyhicks@...ux.microsoft.com, sashal@...nel.org, jmorris@...ei.org,
        nramas@...ux.microsoft.com, linux-integrity@...r.kernel.org,
        selinux@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, dm-devel@...hat.com
Subject: Re: [PATCH v10 0/8] IMA: support for measuring kernel integrity
 critical data

On Thu, 2021-01-07 at 20:07 -0800, Tushar Sugandhi wrote:
> IMA measures files and buffer data such as keys, command-line arguments
> passed to the kernel on kexec system call, etc.  While these measurements
> are necessary for monitoring and validating the integrity of the system,
> they are not sufficient.  Various data structures, policies, and states
> stored in kernel memory also impact the integrity of the system.
> Several kernel subsystems contain such integrity critical data -
> e.g.  LSMs like SELinux, AppArmor etc.  or device-mapper targets like
> dm-crypt, dm-verity, dm-integrity etc.  These kernel subsystems help
> protect the integrity of a system.  Their integrity critical data is not
> expected to change frequently during run-time.  Some of these structures
> cannot be defined as __ro_after_init, because they are initialized later.
> 
> For a given system, various external services/infrastructure tools
> (including the attestation service) interact with it - both during the
> setup and during rest of the system run-time.  They share sensitive data
> and/or execute critical workload on that system.  The external services
> may want to verify the current run-time state of the relevant kernel
> subsystems before fully trusting the system with business critical
> data/workload.  For instance, verifying that SELinux is in "enforce" mode
> along with the expected policy, disks are encrypted with a certain
> configuration, secure boot is enabled etc.
> 
> This series provides the necessary IMA functionality for kernel
> subsystems to ensure their configuration can be measured:
>   - by kernel subsystems themselves,
>   - in a tamper resistant way,
>   - and re-measured - triggered on state/configuration change.
> 
> This patch set:
>   - defines a new IMA hook ima_measure_critical_data() to measure
>     integrity critical data,
>   - limits the critical data being measured based on a label,
>   - defines a builtin critical data measurement policy,
>   - and includes an SELinux consumer of the new IMA critical data hook.

Thanks Tushar, Lakshmi.  This patch set is queued in the next-
integrity-testing branch.

Mimi