linux-kernel - Re: [PATCH v4] certs: Add EFI_CERT_X509

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Date:   Thu, 10 Dec 2020 09:49:08 +0000
From:   David Howells <dhowells@...hat.com>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     dhowells@...hat.com, dwmw2@...radead.org,
        jarkko.sakkinen@...ux.intel.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, jmorris@...ei.org, serge@...lyn.com,
        nayna@...ux.ibm.com, zohar@...ux.ibm.com, erichte@...ux.ibm.com,
        mpe@...erman.id.au, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH v4] certs: Add EFI_CERT_X509_GUID support for dbx entries

Eric Snowberg <eric.snowberg@...cle.com> wrote:

> Add support for EFI_CERT_X509_GUID dbx entries. When a EFI_CERT_X509_GUID
> is found, it is added as an asymmetrical key to the .blacklist keyring.
> Anytime the .platform keyring is used, the keys in the .blacklist keyring
> are referenced, if a matching key is found, the key will be rejected.

Ummm...  Why this way and not as a blacklist key which takes up less space?
I'm guessing that you're using the key chain matching logic.  We really only
need to blacklist the key IDs.

Also, what should happen if a revocation cert rejected by the blacklist?

> +int mark_key_revocationlisted(const char *data, size_t size)

Hmmm...  The name looks wrong, but I can see the potential issue that kernel
keys can actually be marked revoked as a separate concept.  How about
add_key_to_revocation_list() and is_key_on_revocation_list().

David