linux-kernel - Re: [PATHC v2 0/9] ima: carry the measurement list across kexec

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Message-Id: <20160831135047.4b05a7f912f158ed5f888241@linux-foundation.org>
Date:   Wed, 31 Aug 2016 13:50:47 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:     linux-security-module <linux-security-module@...r.kernel.org>,
        linux-ima-devel@...ts.sourceforge.net,
        Dave Young <dyoung@...hat.com>, kexec@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
Subject: Re: [PATHC v2 0/9] ima: carry the measurement list across kexec

On Tue, 30 Aug 2016 18:40:02 -0400 Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:

> The TPM PCRs are only reset on a hard reboot.  In order to validate a
> TPM's quote after a soft reboot (eg. kexec -e), the IMA measurement list
> of the running kernel must be saved and then restored on the subsequent
> boot, possibly of a different architecture.
> 
> The existing securityfs binary_runtime_measurements file conveniently
> provides a serialized format of the IMA measurement list. This patch
> set serializes the measurement list in this format and restores it.
> 
> Up to now, the binary_runtime_measurements was defined as architecture
> native format.  The assumption being that userspace could and would
> handle any architecture conversions.  With the ability of carrying the
> measurement list across kexec, possibly from one architecture to a
> different one, the per boot architecture information is lost and with it
> the ability of recalculating the template digest hash.  To resolve this
> problem, without breaking the existing ABI, this patch set introduces
> the boot command line option "ima_canonical_fmt", which is arbitrarily
> defined as little endian.
> 
> The need for this boot command line option will be limited to the
> existing version 1 format of the binary_runtime_measurements.
> Subsequent formats will be defined as canonical format (eg. TPM 2.0
> support for larger digests).
> 
> This patch set pre-req's Thiago Bauermann's "kexec_file: Add buffer
> hand-over for the next kernel" patch set. 
> 
> These patches can also be found in the next-kexec-restore branch of:
> git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git

I'll merge these into -mm to get some linux-next exposure.  I don't
know what your upstream merge planes will be?