linux-kernel - Re: [PATCH v3 08/10] certs: Check that builtin blacklist hashes are valid

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Message-ID: <11ce77c9-7b43-e2a0-55bc-c0035bf3d681@digikod.net>
Date:   Wed, 20 Jan 2021 12:57:55 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     Jarkko Sakkinen <jarkko@...nel.org>
Cc:     David Howells <dhowells@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        "David S . Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        James Morris <jmorris@...ei.org>,
        Mickaël Salaün <mic@...ux.microsoft.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        "Serge E . Hallyn" <serge@...lyn.com>, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCH v3 08/10] certs: Check that builtin blacklist hashes are
 valid


On 20/01/2021 06:19, Jarkko Sakkinen wrote:
> On Thu, Jan 14, 2021 at 04:19:07PM +0100, Mickaël Salaün wrote:
>> From: Mickaël Salaün <mic@...ux.microsoft.com>
>>
>> Add and use a check-blacklist-hashes.awk script to make sure that the
>> builtin blacklist hashes will be approved by the run time blacklist
>> description checks.  This is useful to debug invalid hash formats, and
>> it make sure that previous hashes which could have been loaded in the
>> kernel (but ignored) are now noticed and deal with by the user.
>>
>> Cc: David Howells <dhowells@...hat.com>
>> Cc: David Woodhouse <dwmw2@...radead.org>
>> Signed-off-by: Mickaël Salaün <mic@...ux.microsoft.com>
>> Acked-by: Jarkko Sakkinen <jarkko@...nel.org>
> 
> I get this with a self-signed cert:
> 
> certs/Makefile:18: *** target pattern contains no '%'.  Stop.
> 
> CONFIG_SYSTEM_BLACKLIST_HASH_LIST="tbs:8eed1340eef37c1dc84d996406ad05c7dbb3eade19132d688408ca2f63904869"

As said in the Kconfig documentation for
CONFIG_SYSTEM_BLACKLIST_HASH_LIST, you need to provide a file with the
list, not to set the string directly in the configuration variable. This
patch series didn't change this behavior. The same kind of macros are
used for CONFIG_MODULE_SIG_KEY.

> 
> I used the script in 10/10 to test this, which is another
> reamark: the patches are in invalid order, as you need to
> apply 10/10 before you can test  8/10.

I'll move patch 10/10 earlier but this kind of formatting was already
required (but silently ignored) for this option to be really taken into
account. Only the kernel code was available to understand how to
effectively create such hash.

> 
> /Jarkko
>