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

From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
	bauerman@linux.ibm.com, robh@kernel.org,
	gregkh@linuxfoundation.org, james.morse@arm.com,
	catalin.marinas@arm.com, sashal@kernel.org, will@kernel.org,
	mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
	robh+dt@kernel.org, frowand.list@gmail.com,
	vincenzo.frascino@arm.com, mark.rutland@arm.com,
	dmitry.kasatkin@gmail.com, jmorris@namei.org, serge@hallyn.com,
	pasha.tatashin@soleen.com, allison@lohutok.net,
	kstewart@linuxfoundation.org, takahiro.akashi@linaro.org,
	tglx@linutronix.de, masahiroy@kernel.org, bhsharma@redhat.com,
	mbrugger@suse.com, hsinyi@chromium.org, tao.li@vivo.com,
	christophe.leroy@c-s.fr
Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org, prsriva@linux.microsoft.com,
	balajib@linux.microsoft.com
Subject: Re: [PATCH v8 0/4] Carry forward IMA measurement log on kexec on ARM64
Date: Tue, 3 Nov 2020 11:26:45 -0800	[thread overview]
Message-ID: <1f01055c-acb8-6497-0144-dfeb78f08eee@linux.microsoft.com> (raw)
In-Reply-To: <053cf58ae21f2e7088e22eedf8c5ee6e73a1e835.camel@linux.ibm.com>

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