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Message-ID: <10fb7958-c6e1-e8c9-8802-f85f2a9311ed@linux.microsoft.com>
Date: Sat, 21 Nov 2020 11:47:03 -0800
From: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To: Rob Herring <robh@...nel.org>
Cc: zohar@...ux.ibm.com, bauerman@...ux.ibm.com,
gregkh@...uxfoundation.org, james.morse@....com,
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Subject: Re: [PATCH v9 0/8] Carry forward IMA measurement log on kexec on
ARM64
On 11/21/20 6:38 AM, Lakshmi Ramasubramanian wrote:
> On 11/21/20 5:57 AM, Rob Herring wrote:
>> 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.
>
> I am not sure I am following you. Could you please clarify -
> In this patch series, per your suggestion, I have moved the architecture
> independent kexec code to "drivers/of".
>
> => drivers/of/ima_kexec.c
> => drivers/of/kexec_fdt.c
>
> Please let me know if I missed something.
The following two arch independent kexec functions are required only
when CONFIG_IMA is enabled. So I moved them under security/integrity/ima
=> ima_get_kexec_buffer()
=> ima_free_kexec_buffer()
But the other arch independent kexec functions have been moved to
drivers/of.
I am not sure if you wanted ima_get_kexec_buffer() and
ima_free_kexec_buffer() to also be moved to "drivers/of". Please clarify.
thanks,
-lakshmi
>>> 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?
>
> Since the functions defined in "ima_kexec.c" and "kexec_fdt.c" are
> enabled on 2 different kernel CONFIGs, keeping them in 2 files enables
> us to avoid using "#ifdef" in C files.
>
> thanks,
> -lakshmi
>
>>
>>> 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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