[PATCH v3] ima: Access decompressed kernel module to verify appended signature

[Mimi Zohar]

Hi Coiby,

On Wed, 2025-11-19 at 11:47 +0800, Coiby Xu wrote:
> Currently, when in-kernel module decompression (CONFIG_MODULE_DECOMPRESS)
> is enabled, IMA has no way to verify the appended module signature as it
> can't decompress the module.
> 
> Define a new kernel_read_file_id enumerate READING_MODULE_COMPRESSED so
> IMA can know only to collect original module data hash on
> READING_MODULE_COMPRESSED and defer appraising/measuring it until on
> READING_MODULE when the module has been decompressed.

This paragraph is a bit awkward.  Perhaps something like:

-> so IMA can calculate the compressed kernel module data hash and defer
measuring/appraising ...

> 
> Before enabling in-kernel module decompression, a kernel module in
> initramfs can still be loaded with ima_policy=secure_boot. So adjust the
> kernel module rule in secure_boot policy to allow either an IMA
> signature OR an appended signature i.e. to use
> "appraise func=MODULE_CHECK appraise_type=imasig|modsig".
> 
> Reported-by: Karel Srot <ksrot at redhat.com>
> Suggested-by: Mimi Zohar <zohar at linux.ibm.com>
> Suggested-by: Paul Moore <paul at paul-moore.com>
> Signed-off-by: Coiby Xu <coxu at redhat.com>

Thanks, Coiby!

The patch applies cleanly to linus' tree, but needs to be applied to next-
integrity.  Please re-base.

-- 

thanks,

Mimi