Re: [PATCH] block/partitions: detect LUKS-formatted disks

[Milan Broz <gmazyland@gmail.com>]

On 7/4/25 8:28 PM, Robin H. Johnson wrote:
> If an entire device is formatted as LUKS, there is a small chance it
> maybe be detected as an Atari/AHDI disk - causing the kernel to create
> partitions, and confusing other systems.
> 
> Detect the LUKS header before the Atari partition table to prevent this
> from creating partitions on top of the LUKS volume.

Please, no. This is a horrible hack.

LUKS is not a partition. It is a completely userspace concept, detection should not be in the kernel at all.
Moreover, the detection below is oversimplified; the second header can be on multiple offsets.

The same problem can happen with Veracrypt or other systems that randomize data.

The Atari partition is known to use very weak detection, but I think blkid added some more hints to check validity in userspace - why is it not enough?
Is anything from this logic missing in the kernel?

If it is not solvable, you should turn off Atari partition detection as it is unreliable.

Milan

> 
> Link: https://unix.stackexchange.com/questions/561745/what-are-the-md-partitions-under-a-mdadm-array
> Link: https://github.com/rook/rook/issues/7940
> Link: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1531404
> Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>