linux-kernel - Re: [PATCH v7 2/4] powerpc: Refactor kexec functions to move arch independent code to ima

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Date:   Tue, 20 Oct 2020 16:01:23 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        bauerman@...ux.ibm.com, robh@...nel.org,
        gregkh@...uxfoundation.org, james.morse@....com,
        catalin.marinas@....com, sashal@...nel.org, will@...nel.org,
        mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        robh+dt@...nel.org, frowand.list@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        dmitry.kasatkin@...il.com, jmorris@...ei.org, serge@...lyn.com,
        pasha.tatashin@...een.com, allison@...utok.net,
        kstewart@...uxfoundation.org, takahiro.akashi@...aro.org,
        tglx@...utronix.de, masahiroy@...nel.org, bhsharma@...hat.com,
        mbrugger@...e.com, hsinyi@...omium.org, tao.li@...o.com,
        christophe.leroy@....fr
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, prsriva@...ux.microsoft.com,
        balajib@...ux.microsoft.com
Subject: Re: [PATCH v7 2/4] powerpc: Refactor kexec functions to move arch
 independent code to ima

On Wed, 2020-09-30 at 13:59 -0700, Lakshmi Ramasubramanian wrote:
> The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(),
> that handle carrying forward the IMA measurement logs on kexec for
> powerpc do not have architecture specific code, but they are currently
> defined for powerpc only.
> 
> Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA
> subsystem. A later patch in this series will use these functions for
> carrying forward the IMA measurement log for ARM64.
> 
> With the above refactoring arch/powerpc/kexec/ima.c contains only
> functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile
> in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only
> when CONFIG_IMA_KEXEC is enabled.
> 
> Move ima_dump_measurement_list() and ima_add_kexec_buffer() to
> a new file namely ima_kexec_fdt.c in IMA. Update
> security/integrity/ima/Makefile to include ima_kexec_fdt.c only
> when CONFIG_IMA_KEXEC is enabled.
> 
> Co-developed-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
> Signed-off-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>

The existing support for carrying the IMA measurement list across kexec
is limited to powerpc.  This patch set is adding similar support for
arm64, making as much of the existing code as generic as possible. 
However ima_dump_measurement_list() is already generic, but for some
reason this patch moves it to ima_kexec_fdt.c.  ima_kexec_fdt.c should
be limited to device tree specific code.

This patch is probably doing the right thing, but the way the patch is
formatted it replaces parts of a function with a different function. 
With the changes suggested above and in 1/4,  the next version should
be clearer.

thanks,

Mimi