[PATCH v3 06/10] certs: Make blacklist_vet_description() more strict

[Jarkko Sakkinen]

On Thu, Jan 14, 2021 at 04:19:05PM +0100, Mickaël Salaün wrote:
> From: Mickaël Salaün <mic at linux.microsoft.com>
> 
> 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 at redhat.com>
> Cc: David Woodhouse <dwmw2 at infradead.org>
> Signed-off-by: Mickaël Salaün <mic at linux.microsoft.com>
> Acked-by: Jarkko Sakkinen <jarkko at 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".

/Jarkko