Message-ID: <20201121135719.GA2134870@robh.at.kernel.org>
Date:   Sat, 21 Nov 2020 07:57:19 -0600
From:   Rob Herring <robh@...nel.org>
To:     Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
Cc:     zohar@...ux.ibm.com, bauerman@...ux.ibm.com,
        gregkh@...uxfoundation.org, james.morse@....com,
        catalin.marinas@....com, sashal@...nel.org, will@...nel.org,
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        kstewart@...uxfoundation.org, takahiro.akashi@...aro.org,
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        mbrugger@...e.com, hsinyi@...omium.org, tao.li@...o.com,
        christophe.leroy@....fr, 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 v9 0/8] Carry forward IMA measurement log on kexec on
 ARM64

On Fri, Nov 13, 2020 at 11:22:35AM -0800, Lakshmi Ramasubramanian wrote:
> On kexec file load Integrity Measurement Architecture (IMA) subsystem
> may verify the IMA signature of the kernel and initramfs, and measure
> it. The command line parameters passed to the kernel in the kexec call
> may also be measured by IMA. A remote attestation service can verify
> a TPM quote based on the TPM event log, the IMA measurement list, and
> the TPM PCR data. This can be achieved only if the IMA measurement log
> is carried over from the current kernel to the next kernel across
> the kexec call.
> 
> powerpc already supports carrying forward the IMA measurement log on
> kexec. This patch set adds support for carrying forward the IMA
> measurement log on kexec on ARM64. 
> 
> This patch set moves the platform independent code defined for powerpc
> such that it can be reused for other platforms as well. A chosen node
> namely "linux,ima-kexec-buffer" is added to the DTB for ARM64 to hold
> the address and the size of the memory reserved to carry
> the IMA measurement log.
> 
> This patch set has been tested for ARM64 platform using QEMU.
> I would like help from the community for testing this change on powerpc.
> Thanks.

As I mentioned previously, please move the kexec code to drivers/of/. Or 
at least put the infrastructure in place so we're not defining public 
IMA functions and then making them static later.
 
> This patch set is based on
> commit af5043c89a8e ("Merge tag 'acpi-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm")
> in https://github.com/torvalds/linux "master" branch.
> 
> Changelog:
> 
> v9
>   - Moved delete_fdt_mem_rsv() to drivers/of/kexec_fdt.c
>   - Defined a new function get_ima_kexec_buffer() in
>     drivers/of/ima_kexec.c to replace do_get_kexec_buffer()
>   - Changed remove_ima_kexec_buffer() to the original function name
>     remove_ima_buffer()
>   - Moved remove_ima_buffer() to drivers/of/ima_kexec.c
>   - Moved ima_get_kexec_buffer() and ima_free_kexec_buffer()
>     to security/integrity/ima/ima_kexec.c
> 
> v8:
>   - Moved remove_ima_kexec_buffer(), do_get_kexec_buffer(), and
>     delete_fdt_mem_rsv() to drivers/of/fdt.c
>   - Moved ima_dump_measurement_list() and ima_add_kexec_buffer()
>     back to security/integrity/ima/ima_kexec.c
> 
> v7:
>   - Renamed remove_ima_buffer() to remove_ima_kexec_buffer() and moved
>     this function definition to kernel.
>   - Moved delete_fdt_mem_rsv() definition to kernel
>   - Moved ima_dump_measurement_list() and ima_add_kexec_buffer() to
>     a new file namely ima_kexec_fdt.c in IMA
> 
> v6:
>   - Remove any existing FDT_PROP_IMA_KEXEC_BUFFER property in the device
>     tree and also its corresponding memory reservation in the currently
>     running kernel.
>   - Moved the function remove_ima_buffer() defined for powerpc to IMA
>     and renamed the function to ima_remove_kexec_buffer(). Also, moved
>     delete_fdt_mem_rsv() from powerpc to IMA.
> 
> v5:
>   - Merged get_addr_size_cells() and do_get_kexec_buffer() into a single
>     function when moving the arch independent code from powerpc to IMA
>   - Reverted the change to use FDT functions in powerpc code and added
>     back the original code in get_addr_size_cells() and
>     do_get_kexec_buffer() for powerpc.
>   - Added fdt_add_mem_rsv() for ARM64 to reserve the memory for
>     the IMA log buffer during kexec.
>   - Fixed the warning reported by kernel test bot for ARM64
>     arch_ima_add_kexec_buffer() - moved this function to a new file
>     namely arch/arm64/kernel/ima_kexec.c
> 
> v4:
>   - Submitting the patch series on behalf of the original author
>     Prakhar Srivastava <prsriva@...ux.microsoft.com>
>   - Moved FDT_PROP_IMA_KEXEC_BUFFER ("linux,ima-kexec-buffer") to
>     libfdt.h so that it can be shared by multiple platforms.
> 
> v3:
> Breakup patches further into separate patches.
>   - Refactoring non architecture specific code out of powerpc
>   - Update powerpc related code to use fdt functions
>   - Update IMA buffer read related code to use of functions
>   - Add support to store the memory information of the IMA
>     measurement logs to be carried forward.
>   - Update the property strings to align with documented nodes
>     https://github.com/devicetree-org/dt-schema/pull/46
> 
> v2:
>   Break patches into separate patches.
>   - Powerpc related Refactoring
>   - Updating the docuemntation for chosen node
>   - Updating arm64 to support IMA buffer pass
> 
> v1:
>   Refactoring carrying over IMA measuremnet logs over Kexec. This patch
>     moves the non-architecture specific code out of powerpc and adds to
>     security/ima.(Suggested by Thiago)
>   Add Documentation regarding the ima-kexec-buffer node in the chosen
>     node documentation
> 
> v0:
>   Add a layer of abstraction to use the memory reserved by device tree
>     for ima buffer pass.
>   Add support for ima buffer pass using reserved memory for arm64 kexec.
>     Update the arch sepcific code path in kexec file load to store the
>     ima buffer in the reserved memory. The same reserved memory is read
>     on kexec or cold boot.
> 
> Lakshmi Ramasubramanian (8):
>   powerpc: fix compiler warnings and errors
>   powerpc: Move delete_fdt_mem_rsv() to drivers/of
>   ima: Define get_ima_kexec_buffer() in drivers/of
>   powerpc: Use get_ima_kexec_buffer to get ima kexec buffer
>   powerpc: Move remove_ima_buffer() to drivers/of
>   powerpc: Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to
>     ima
>   arm64: Store IMA log information in kimage used for kexec
>   arm64: Add IMA kexec buffer to DTB
> 
>  arch/arm64/Kconfig                     |   1 +
>  arch/arm64/include/asm/ima.h           |  18 +++++
>  arch/arm64/include/asm/kexec.h         |   3 +
>  arch/arm64/kernel/Makefile             |   1 +
>  arch/arm64/kernel/ima_kexec.c          |  34 ++++++++
>  arch/arm64/kernel/machine_kexec_file.c |  18 +++++
>  arch/powerpc/include/asm/ima.h         |  11 +--
>  arch/powerpc/include/asm/kexec.h       |   1 -
>  arch/powerpc/kexec/Makefile            |   7 +-
>  arch/powerpc/kexec/file_load.c         |  32 --------
>  arch/powerpc/kexec/ima.c               | 106 ++-----------------------
>  drivers/of/Makefile                    |   9 +++

>  drivers/of/ima_kexec.c                 |  91 +++++++++++++++++++++
>  drivers/of/kexec_fdt.c                 |  55 +++++++++++++

Does this need to be 2 files? Just kexec.c?

>  include/linux/kexec.h                  |  24 ++++++
>  security/integrity/ima/ima_kexec.c     |  51 ++++++++++++
>  16 files changed, 313 insertions(+), 149 deletions(-)
>  create mode 100644 arch/arm64/include/asm/ima.h
>  create mode 100644 arch/arm64/kernel/ima_kexec.c
>  create mode 100644 drivers/of/ima_kexec.c
>  create mode 100644 drivers/of/kexec_fdt.c
> 
> -- 
> 2.29.2
> 

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