Re: [PATCH v3 09/10] certs: Allow root user to append signed hashes to the blacklist keyring

Mickaël Salaün
2021-01-20T12:00:13Z

On 20/01/2021 06:23, Jarkko Sakkinen wrote:
> On Thu, Jan 14, 2021 at 04:19:08PM +0100, Mickaël Salaün wrote:
>> From: Mickaël Salaün <mic@linux.microsoft.com>
>>
>> Add a kernel option SYSTEM_BLACKLIST_AUTH_UPDATE to enable the root user
>> to dynamically add new keys to the blacklist keyring. This enables to
>> invalidate new certificates, either from being loaded in a keyring, or
>> from being trusted in a PKCS#7 certificate chain. This also enables to
>> add new file hashes to be denied by the integrity infrastructure.
>>
>> Being able to untrust a certificate which could have normaly been
>> trusted is a sensitive operation. This is why adding new hashes to the
>> blacklist keyring is only allowed when these hashes are signed and
>> vouched by the builtin trusted keyring. A blacklist hash is stored as a
>> key description. The PKCS#7 signature of this description must be
>> provided as the key payload.
>>
>> Marking a certificate as untrusted should be enforced while the system
>> is running. It is then forbiden to remove such blacklist keys.
>>
>> Update blacklist keyring and blacklist key access rights:
>> * allows the root user to search for a specific blacklisted hash, which
>> make sense because the descriptions are already viewable;
>> * forbids key update;
>> * restricts kernel rights on the blacklist keyring to align with the
>> root user rights.
>>
>> See the help in tools/certs/print-cert-tbs-hash.sh provided by a
>> following commit.
>
> Please re-order patches in a way that print-cert-tbs-hash.sh is
> available before this. That way we get rid of this useless remark.

OK

>
>> Cc: David Howells <dhowells@redhat.com>
>> Cc: David Woodhouse <dwmw2@infradead.org>
>> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
>
> /Jarkko
>