Message-ID: <bfccfb6d-376e-b66e-fb35-754f5e88d6a7@linux.vnet.ibm.com>
Date:   Thu, 11 Nov 2021 17:23:31 -0500
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Subject: Re: [PATCH 0/3] KEXEC_SIG with appended signature
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To:     =?UTF-8?Q?Michal_Such=c3=a1nek?= <msuchanek@suse.de>
Cc:     keyrings@vger.kernel.org, Rob Herring <robh@kernel.org>,
        linux-s390@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Jessica Yu <jeyu@kernel.org>, linux-kernel@vger.kernel.org,
        David Howells <dhowells@redhat.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Paul Mackerras <paulus@samba.org>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        linuxppc-dev@lists.ozlabs.org,
        Frank van der Linden <fllinden@amazon.com>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Daniel Axtens <dja@axtens.net>
References: <cover.1635948742.git.msuchanek@suse.de>
 <87czneeurr.fsf@dja-thinkpad.axtens.net>
 <20211105131401.GL11195@kunlun.suse.cz>
From:   Nayna <nayna@linux.vnet.ibm.com>
In-Reply-To: <20211105131401.GL11195@kunlun.suse.cz>
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On 11/5/21 09:14, Michal Suchánek wrote:
> On Fri, Nov 05, 2021 at 09:55:52PM +1100, Daniel Axtens wrote:
>> Michal Suchanek <msuchanek@suse.de> writes:
>>
>>> S390 uses appended signature for kernel but implements the check
>>> separately from module loader.
>>>
>>> Support for secure boot on powerpc with appended signature is planned -
>>> grub patches submitted upstream but not yet merged.
>> Power Non-Virtualised / OpenPower already supports secure boot via kexec
>> with signature verification via IMA. I think you have now sent a
>> follow-up series that merges some of the IMA implementation, I just
>> wanted to make sure it was clear that we actually already have support
> So is IMA_KEXEC and KEXEC_SIG redundant?
>
> I see some architectures have both. I also see there is a lot of overlap
> between the IMA framework and the KEXEC_SIG and MODULE_SIg.

Originally, KEXEC_SIG was meant for PECOFF based signatures, while 
IMA_KEXEC mainly supported xattr based signatures.

Power (Non-virtualized/OpenPOWER) doesn't support PECOFF. Extended 
attributes based signature verification doesn't work with netboot. 
That's when appended signature support was added to IMA.

Using IMA_KEXEC has the benefit of being able to enable both signature 
verification and measurement of the kernel image.

Thanks & Regards,

      - Nayna