Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
To:     James Bottomley <jejb@linux.ibm.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Mimi Zohar <zohar@linux.ibm.com>,
        David Howells <dhowells@redhat.com>, keyrings@vger.kernel.org
Cc:     linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-security-module@vger.kernel.org, kernel@pengutronix.de,
        jlu@pengutronix.de
From:   Ahmad Fatoum <a.fatoum@pengutronix.de>
Subject: Migration to trusted keys: sealing user-provided key?
Message-ID: <74830d4f-5a76-8ba8-aad0-0d79f7c01af9@pengutronix.de>
Date:   Thu, 28 Jan 2021 18:31:57 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hello,

I've been looking into how a migration to using trusted/encrypted keys
would look like (particularly with dm-crypt).

Currently, it seems the the only way is to re-encrypt the partitions
because trusted/encrypted keys always generate their payloads from
RNG.

If instead there was a key command to initialize a new trusted/encrypted
key with a user provided value, users could use whatever mechanism they
used beforehand to get a plaintext key and use that to initialize a new
trusted/encrypted key. From there on, the key will be like any other
trusted/encrypted key and not be disclosed again to userspace.

What are your thoughts on this? Would an API like

  keyctl add trusted dmcrypt-key 'set <content>' # user-supplied content

be acceptable?

Cheers,
Ahmad

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |