[PATCH] lockdown: kexec_file: prevent unsigned kernel image when KEXEC_SIG not enabled

[Mimi Zohar]

Hi Coiby,

On Mon, 2022-11-21 at 15:29 +0800, Coiby Xu wrote:
> A kernel builder may not enable KEXEC_SIG and some architectures like
> ppc64 simply don't have KEXEC_SIG. In these cases, unless both
> IMA_ARCH_POLICY and secure boot also enabled, lockdown doesn't prevent
> unsigned kernel image from being kexec'ed via the kexec_file_load
> syscall whereas it could prevent one via the kexec_load syscall. Mandate
> signature verification for those cases.
> 
> Fixes: 155bdd30af17 ("kexec_file: Restrict at runtime if the kernel is locked down")
> Cc: Matthew Garrett <mjg59 at srcf.ucam.org>
> Cc: Jiri Bohac <jbohac at suse.cz>
> Cc: David Howells <dhowells at redhat.com>
> Cc: kexec at lists.infradead.org
> Cc: linux-integrity at vger.kernel.org
> Signed-off-by: Coiby Xu <coxu at redhat.com>

Other than correcting the function name to mandate_signature_verificati
on(),

Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>