linux-kernel - Re: [PATCH v13 2/6] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c

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Date:   Tue, 22 Dec 2020 10:53:37 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, bauerman@...ux.ibm.com,
        robh@...nel.org, takahiro.akashi@...aro.org,
        gregkh@...uxfoundation.org, will@...nel.org,
        catalin.marinas@....com, mpe@...erman.id.au
Cc:     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
Subject: Re: [PATCH v13 2/6] powerpc: Move arch independent ima kexec
 functions to drivers/of/kexec.c

On 12/22/20 6:26 AM, Mimi Zohar wrote:

Hi Mimi,

> 
> On Sat, 2020-12-19 at 09:57 -0800, Lakshmi Ramasubramanian wrote:
>>
>> diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
>> index 4aff6846c772..b6c52608cb49 100644
>> --- a/arch/powerpc/kexec/Makefile
>> +++ b/arch/powerpc/kexec/Makefile
>> @@ -9,13 +9,6 @@ obj-$(CONFIG_PPC32)		+= relocate_32.o
>>   
>>   obj-$(CONFIG_KEXEC_FILE)	+= file_load.o ranges.o file_load_$(BITS).o elf_$(BITS).o
>>   
>> -ifdef CONFIG_HAVE_IMA_KEXEC
>> -ifdef CONFIG_IMA
>> -obj-y				+= ima.o
>> -endif
>> -endif
> 
> Notice how "kexec/ima.o" is only included if the architecture supports
> it and IMA is configured.  In addition only if CONFIG_IMA_KEXEC is
> configured, is the IMA measurement list carried across kexec.  After
> moving the rest of ima.c to drivers/of/kexec.c, this changes.   Notice
> how drivers/of/Kconfig includes kexec.o:
> 
> obj-$(CONFIG_KEXEC_FILE) += kexec.o
> 
> It is not dependent on CONFIG_HAVE_IMA_KEXEC.  Shouldn't all of the
> functions defined in ima.c being moved to kexec.o be defined within a
> CONFIG_HAVE_IMA_KEXEC ifdef?
> 

Thanks for reviewing the changes.

In "drivers/of/kexec.c" the function remove_ima_buffer() is defined 
under "#ifdef CONFIG_HAVE_IMA_KEXEC"

setup_ima_buffer() is defined under "#ifdef CONFIG_IMA_KEXEC" - the same 
way it was defined in "arch/powerpc/kexec/ima.c".

As you know, CONFIG_IMA_KEXEC depends on CONFIG_HAVE_IMA_KEXEC (as 
defined in "security/integrity/ima/Kconfig").

ima_get_kexec_buffer() and ima_free_kexec_buffer() are unconditionally 
defined in "drivers/of/kexec.c" even though they are called only when 
CONFIG_HAVE_IMA_KEXEC is enabled. I will update these two functions to 
be moved under "#ifdef CONFIG_HAVE_IMA_KEXEC"

Rob/Mimi/Thiago - Please let me know if you have other comments in the 
v13 patches. Will address those as well and post v14.

thanks,
  -lakshmi