Re: [PATCH 2/3] boot: fit: cover the dm-verity roothash with the config signature

[Tom Rini <trini@konsulko.com>]

[-- Attachment #1: Type: text/plain, Size: 1213 bytes --]

On Sun, Jul 12, 2026 at 01:33:21AM +0100, Daniel Golle wrote:

> A dm-verity protected filesystem image is not hashed by U-Boot when it
> is loaded; its integrity is delegated to the kernel, which validates the
> filesystem on the fly against the roothash taken from the FIT dm-verity
> subnode. The roothash is therefore the sole integrity anchor for the
> filesystem, yet fit_config_add_hash() only added the image node, its
> hash subnodes and its cipher subnode to the signed region, leaving the
> dm-verity subnode (roothash, salt and block parameters) unsigned.
> 
> An attacker able to rewrite the boot medium could then replace both the
> filesystem and the roothash, recompute a matching dm-verity tree and
> keep the configuration signature valid, defeating verified boot for the
> root filesystem.
> 
> Add the dm-verity subnode to the list of nodes covered by the
> configuration signature, both when signing (tools/image-host.c) and when
> verifying (boot/image-fit-sig.c), so the roothash and salt are
> authenticated together with the rest of the configuration.
> 
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Reviewed-by: Tom Rini <trini@konsulko.com>

-- 
Tom

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]