Re: [PATCH 0/3] KEXEC_SIG with appended signature

On 11/5/21 09:14, Michal Suchánek wrote:

On Fri, Nov 05, 2021 at 09:55:52PM +1100, Daniel Axtens wrote:

quoted

Michal Suchanek [off-list ref] writes:

quoted

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