Re: [PATCH v8 0/4] Carry forward IMA measurement log on kexec on ARM64

Lakshmi Ramasubramanian
2020-11-03T19:26:49Z

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