Re: [PATCH v9 0/8] Carry forward IMA measurement log on kexec on ARM64

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

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.

>   
>> 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@linux.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
>>