linux-kernel - Re: [PATCH] kexec: Do not verify the signature without the lockdown or mandatory signature

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Date:   Wed, 27 May 2020 12:16:18 +0200
From:   Jiri Bohac <jbohac@...e.cz>
To:     lijiang <lijiang@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        ebiederm@...ssion.com, jmorris@...ei.org, mjg59@...gle.com,
        dyoung@...hat.com, bhe@...hat.com
Subject: Re: [PATCH] kexec: Do not verify the signature without the lockdown
 or mandatory signature

On Wed, May 27, 2020 at 12:08:12PM +0800, lijiang wrote:
> Or the following change looks better? What's your opinion?
> 
> static int
> kimage_validate_signature(struct kimage *image)
> {
>         int ret;
> 
>         ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
>                                            image->kernel_buf_len);
>         if (ret) {
> 
>                 if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
>                         pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
>                         return ret;
>                 }
> 
>                 /*
>                  * If IMA is guaranteed to appraise a signature on the kexec
>                  * image, permit it even if the kernel is otherwise locked
>                  * down.
>                  */
>                 if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
>                     security_locked_down(LOCKDOWN_KEXEC))
>                         return -EPERM;
> 
>                 pr_debug("kernel signature verification failed (%d).\n", ret);
>         }
> 
>         return 0;
> }

Looks good to me, thanks!

-- 
Jiri Bohac <jbohac@...e.cz>
SUSE Labs, Prague, Czechia