linux-kernel - Re: [PATCH v15 10/10] arm64: Add IMA log information in kimage used for kexec

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Message-ID: <dec23eb8-0b27-3227-d1ef-f759338a7f9f@linux.microsoft.com>
Date:   Wed, 27 Jan 2021 09:56:53 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Will Deacon <will@...nel.org>
Cc:     zohar@...ux.ibm.com, bauerman@...ux.ibm.com, robh@...nel.org,
        takahiro.akashi@...aro.org, gregkh@...uxfoundation.org,
        catalin.marinas@....com, mpe@...erman.id.au, james.morse@....com,
        sashal@...nel.org, benh@...nel.crashing.org, paulus@...ba.org,
        frowand.list@...il.com, vincenzo.frascino@....com,
        mark.rutland@....com, dmitry.kasatkin@...il.com, jmorris@...ei.org,
        serge@...lyn.com, pasha.tatashin@...een.com, allison@...utok.net,
        masahiroy@...nel.org, bhsharma@...hat.com, mbrugger@...e.com,
        hsinyi@...omium.org, tao.li@...o.com, christophe.leroy@....fr,
        prsriva@...ux.microsoft.com, balajib@...ux.microsoft.com,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v15 10/10] arm64: Add IMA log information in kimage used
 for kexec

On 1/27/21 8:54 AM, Will Deacon wrote:

Hi Will,

> On Fri, Jan 15, 2021 at 09:30:17AM -0800, Lakshmi Ramasubramanian wrote:
>> Address and size of the buffer containing the IMA measurement log need
>> to be passed from the current kernel to the next kernel on kexec.
>>
>> Add address and size fields to "struct kimage_arch" for ARM64 platform
>> to hold the address and size of the IMA measurement log buffer.
>>
>> Update CONFIG_KEXEC_FILE to select CONFIG_HAVE_IMA_KEXEC, if CONFIG_IMA
>> is enabled, to indicate that the IMA measurement log information is
>> present in the device tree for ARM64.
>>
>> Co-developed-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
>> Signed-off-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
>> Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
>> ---
>>   arch/arm64/Kconfig             | 1 +
>>   arch/arm64/include/asm/kexec.h | 5 +++++
>>   2 files changed, 6 insertions(+)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 1d466addb078..ea7f7fe3dccd 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -1094,6 +1094,7 @@ config KEXEC
>>   config KEXEC_FILE
>>   	bool "kexec file based system call"
>>   	select KEXEC_CORE
>> +	select HAVE_IMA_KEXEC if IMA
>>   	help
>>   	  This is new version of kexec system call. This system call is
>>   	  file based and takes file descriptors as system call argument
>> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
>> index d24b527e8c00..2bd19ccb6c43 100644
>> --- a/arch/arm64/include/asm/kexec.h
>> +++ b/arch/arm64/include/asm/kexec.h
>> @@ -100,6 +100,11 @@ struct kimage_arch {
>>   	void *elf_headers;
>>   	unsigned long elf_headers_mem;
>>   	unsigned long elf_headers_sz;
>> +
>> +#ifdef CONFIG_IMA_KEXEC
>> +	phys_addr_t ima_buffer_addr;
>> +	size_t ima_buffer_size;
>> +#endif
> 
> Why do these need to be in the arch structure instead of 'struct kimage'?
> 

Currently, only powerpc and, with this patch set, arm64 have support for 
carrying forward IMA measurement list across kexec system call. The 
above fields are used for tracking IMA measurement list.

Do you see a reason to move these fields to "struct kimage"?

thanks,
  -lakshmi