Re: [PATCH v3 1/7] kexec_file: allow to place kexec_buf randomly

[Coiby Xu]

On Mon, May 20, 2024 at 02:16:43PM +0800, Baoquan He wrote:
> On 04/25/24 at 06:04pm, Coiby Xu wrote:
> > Currently, kexec_buf is placed in order which means for the same
> > machine, the info in the kexec_buf is always located at the same
> > position each time the machine is booted. This may cause a risk for
> > sensitive information like LUKS volume key. Now struct kexec_buf has a
> > new field random which indicates it's supposed to be placed in a random
> > position.
>
> Do you want to randomize the key's position for both kdump and kexec
> rebooting? Assume you only want to do that for kdump. If so, we may need
> to make that more specific in code.

Thanks for the suggestion! Currently, no one has requested this feature
for kexec reboot so yes, I only have kdump in mind. But kdump depends
on kexec thus I'm not sure how we can make it kdump specfic. Do you have
a further suggestion?


> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 060835bb82d5..fc1e20d565d5 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -171,6 +171,7 @@ int kexec_image_post_load_cleanup_default(struct kimage *image);
>  * @buf_min:	The buffer can't be placed below this address.
>  * @buf_max:	The buffer can't be placed above this address.
>  * @top_down:	Allocate from top of memory.
> + * @random:	Place the buffer at a random position.

How about a comment here saying this is currently only used by kdump.

--
Best regards,
Coiby