Re: [PATCH v18 00/10] Carry forward IMA measurement log on kexec on ARM64

Rob Herring
2021-02-18T01:26:46Z

On Sat, Feb 13, 2021 at 08:10:38AM -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
> "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.
>
> This patch set is based on
> commit f31e3386a4e9 ("ima: Free IMA measurement buffer after kexec syscall")
> in https://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
> "ima-kexec-fixes" branch.
>
> Changelog:
>
> v18
> - Added a parameter to of_kexec_alloc_and_setup_fdt() for the caller
> to specify additional space needed for the FDT buffer
> - Renamed arm64 and powerpc ELF buffer address field in
> "struct kimage_arch" to elf_load_addr to match x86_64 name.
> - Removed of_ima_add_kexec_buffer() and instead directly set
> ima_buffer_addr and ima_buffer_size in ima_add_kexec_buffer()
> - Moved FDT_EXTRA_SPACE definition from include/linux/of.h to
> drivers/of/kexec.c
>
> v17
> - Renamed of_kexec_setup_new_fdt() to of_kexec_alloc_and_setup_fdt(),
> and moved memory allocation for the new FDT to this function.
>
> v16
> - Defined functions to allocate and free buffer for FDT for powerpc
> and arm64.
> - Moved ima_buffer_addr and ima_buffer_size fields from
> "struct kimage_arch" in powerpc to "struct kimage"
> v15
> - Included Rob's patches in the patch set, and rebased
> the changes to "next-integrity" branch.
> - Allocate memory for DTB, on arm64, using kmalloc() instead of
> vmalloc() to keep it consistent with powerpc implementation.
> - Call of_kexec_setup_new_fdt() from setup_new_fdt_ppc64() and
> remove setup_new_fdt() in the same patch to keep it bisect safe.
>
> v14
> - Select CONFIG_HAVE_IMA_KEXEC for CONFIG_KEXEC_FILE, for powerpc
> and arm64, if CONFIG_IMA is enabled.
> - Use IS_ENABLED() macro instead of "#ifdef" in remove_ima_buffer(),
> ima_get_kexec_buffer(), and ima_free_kexec_buffer().
> - Call of_kexec_setup_new_fdt() from setup_new_fdt_ppc64() and
> remove setup_new_fdt() in "arch/powerpc/kexec/file_load.c".
>
> v13
> - Moved the arch independent functions to drivers/of/kexec.c
> and then refactored the code.
> - Moved arch_ima_add_kexec_buffer() to
> security/integrity/ima/ima_kexec.c
>
> v12
> - Use fdt_appendprop_addrrange() in setup_ima_buffer()
> to setup the IMA measurement list property in
> the device tree.
> - Moved architecture independent functions from
> "arch/powerpc/kexec/ima.c" to "drivers/of/kexec."
> - Deleted "arch/powerpc/kexec/ima.c" and
> "arch/powerpc/include/asm/ima.h".
>
> v11
> - Rebased the changes on the kexec code refactoring done by
> Rob Herring in his "dt/kexec" branch
> - Removed "extern" keyword in function declarations
> - Removed unnecessary header files included in C files
> - Updated patch descriptions per Thiago's comments
>
> v10
> - Moved delete_fdt_mem_rsv(), remove_ima_buffer(),
> get_ima_kexec_buffer, and get_root_addr_size_cells()
> to drivers/of/kexec.c
> - Moved arch_ima_add_kexec_buffer() to
> security/integrity/ima/ima_kexec.c
> - Conditionally define IMA buffer fields in struct kimage_arch
>
> 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 (7):
> arm64: Rename kexec elf_headers_mem to elf_load_addr
> powerpc: Move ima buffer fields to struct kimage
> powerpc: Enable passing IMA log to next kernel on kexec
> powerpc: Move arch independent ima kexec functions to
> drivers/of/kexec.c
> kexec: Use fdt_appendprop_addrrange() to add ima buffer to FDT
> powerpc: Delete unused function delete_fdt_mem_rsv()
> arm64: Enable passing IMA log to next kernel on kexec
>
> Rob Herring (4):
> powerpc: Rename kexec elfcorehdr_addr to elf_load_addr
> of: Add a common kexec FDT setup function
> arm64: Use common of_kexec_alloc_and_setup_fdt()
> powerpc: Use common of_kexec_alloc_and_setup_fdt()

I've applied the series. The merge conflict is not too bad, but will
need a follow on patch to change the powerpc FDT size calculation
(dropping the current FDT's size out).

Thanks for persisting!

Rob