On 20/01/2021 05:16, Jarkko Sakkinen wrote:

On Thu, Jan 14, 2021 at 04:19:05PM +0100, Mickaël Salaün wrote:

quoted

From: Mickaël Salaün <redacted>

Before exposing this new key type to user space, make sure that only
meaningful blacklisted hashes are accepted.  This is also checked for
builtin blacklisted hashes, but a following commit make sure that the
user will notice (at built time) and will fix the configuration if it
already included errors.

Check that a blacklist key description starts with a valid prefix and
then a valid hexadecimal string.

Cc: David Howells <dhowells@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Mickaël Salaün <redacted>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>

In this I'm not as worried about ABI, i.e. you don't have any reason
supply any other data, which doesn't follow these ruels, whereas there
could very well be a script that does format hex "incorrectly".

I think I answered this comment in patch 2/10: there is no ABI breakage,
it only prepares for safe dynamic key addition. Patch 10/10 enables to
avoid using incorrect/useless/mis-leading hashes and force users to fix
these hashes (that were not taken into account)

/Jarkko