linux-kernel - Re: [PATCH v3 06/10] certs: Make blacklist_vet

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Message-ID: <491f8d01-b525-2bcf-68d8-c28bfc9f1532@digikod.net>
Date:   Wed, 20 Jan 2021 12:23:45 +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 06/10] certs: Make blacklist_vet_description() more
 strict


On 20/01/2021 05:16, Jarkko Sakkinen wrote:
> On Thu, Jan 14, 2021 at 04:19:05PM +0100, Mickaël Salaün wrote:
>> From: Mickaël Salaün <mic@...ux.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@...hat.com>
>> Cc: David Woodhouse <dwmw2@...radead.org>
>> Signed-off-by: Mickaël Salaün <mic@...ux.microsoft.com>
>> Acked-by: Jarkko Sakkinen <jarkko@...nel.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
>