| Message ID | 20201030174429.29893-1-nramas@linux.microsoft.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Carry forward IMA measurement log on kexec on ARM64 | expand |
On Fri, 2020-10-30 at 10:44 -0700, 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 > the measurement through the IMA log 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. Nice, but you might want to tweak it a bit. This is just a suggestion. "A remote attestation service can verify a TPM quote based on the TPM event log, the IMA measurement list, and the TPM PCR data". > However in the current implementation the IMA measurement logs are not > carried over on ARM64 platforms. Therefore a remote attestation service > cannot verify the authenticity of the running kernel on ARM64 platforms > when the kernel is updated through the kexec system call. The paragraphs above and below are redundant. The first paragraph already explained why carrying the measurement across kexec is needed. Perhaps drop the above paragraph. > This patch series adds support for carrying forward the IMA measurement > log on kexec on ARM64. powerpc already supports carrying forward > the IMA measurement log on kexec. And invert these sentences, starting the paragraph with "Powerpc already" and ending with ARM64. > > This series refactors the platform independent code defined for powerpc > such that it can be reused for ARM64 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 moves ..." Thanks, Mimi > > This patch series has been tested for ARM64 platform using QEMU. > I would like help from the community for testing this change on powerpc. > Thanks. > > This patch series is based on > commit 598a597636f8 ("Merge tag 'afs-fixes-20201029' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs") > in https://github.com/torvalds/linux "master" branch.
On 11/3/20 7:18 AM, Mimi Zohar wrote: Hi Mimi, > On Fri, 2020-10-30 at 10:44 -0700, 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 >> the measurement through the IMA log 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. > > Nice, but you might want to tweak it a bit. This is just a suggestion. > "A remote attestation service can verify a TPM quote based on the TPM > event log, the IMA measurement list, and the TPM PCR data". Sure - will make this change. > >> However in the current implementation the IMA measurement logs are not >> carried over on ARM64 platforms. Therefore a remote attestation service >> cannot verify the authenticity of the running kernel on ARM64 platforms >> when the kernel is updated through the kexec system call. > > The paragraphs above and below are redundant. The first paragraph > already explained why carrying the measurement across kexec is needed. > Perhaps drop the above paragraph. Sure. > >> This patch series adds support for carrying forward the IMA measurement >> log on kexec on ARM64. powerpc already supports carrying forward >> the IMA measurement log on kexec. > > And invert these sentences, starting the paragraph with "Powerpc > already" and ending with ARM64. Sure. > >> >> This series refactors the platform independent code defined for powerpc >> such that it can be reused for ARM64 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 moves ..." Sure - will make this change. Thanks again for reviewing the patches. Will post the updated patch set shortly. -lakshmi
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 the measurement through the IMA log 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. However in the current implementation the IMA measurement logs are not carried over on ARM64 platforms. Therefore a remote attestation service cannot verify the authenticity of the running kernel on ARM64 platforms when the kernel is updated through the kexec system call. This patch series adds support for carrying forward the IMA measurement log on kexec on ARM64. powerpc already supports carrying forward the IMA measurement log on kexec. This series refactors the platform independent code defined for powerpc such that it can be reused for ARM64 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 series has been tested for ARM64 platform using QEMU. I would like help from the community for testing this change on powerpc. Thanks. This patch series is based on commit 598a597636f8 ("Merge tag 'afs-fixes-20201029' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs") in https://github.com/torvalds/linux "master" branch. Changelog: 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 (4): powerpc: Refactor kexec functions to move arch independent code to drivers/of powerpc: Refactor kexec functions to move arch independent code 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 | 13 +-- arch/powerpc/include/asm/kexec.h | 1 - arch/powerpc/kexec/Makefile | 7 +- arch/powerpc/kexec/file_load.c | 33 +------- arch/powerpc/kexec/ima.c | 111 ++----------------------- drivers/of/fdt.c | 110 ++++++++++++++++++++++++ include/linux/kexec.h | 24 ++++++ include/linux/libfdt.h | 3 + security/integrity/ima/ima_kexec.c | 57 +++++++++++++ 15 files changed, 282 insertions(+), 152 deletions(-) create mode 100644 arch/arm64/include/asm/ima.h create mode 100644 arch/arm64/kernel/ima_kexec.c