-----Original Message-----
From: Jan Lübbe <jlu@pengutronix.de>
Sent: Wednesday, March 6, 2019 5:48 PM
To: Franck Lenormand <redacted>; linux-
kernel@vger.kernel.org; linux-security-module@vger.kernel.org;
keyrings@vger.kernel.org
Cc: Horia Geanta <horia.geanta@nxp.com>; Silvano Di Ninno
[off-list ref]; agk@redhat.com; snitzer@redhat.com; dm-
devel@redhat.com; dhowells@redhat.com; jmorris@namei.org;
serge@hallyn.com; David Gstir [off-list ref]
Subject: Re: [RFC PATCH 0/2] Create CAAM HW key in linux keyring and use in
dmcrypt

Hi Franck,

thanks for working on this!

On Fri, 2019-03-01 at 17:09 +0100, Franck LENORMAND wrote:

quoted

The creation of such structures and its use was not exposed to
userspace so it was complicated to use and required custom
development. We would like to ease this using interface which are known

and used:

quoted

 - Linux key retention service : Allow to generate or load keys in a
        keyring which can be used by applications.
 - dm-crypt : device mapper allowing to encrypt data.

The capacity to generate or load keys already available in the Linux
key retention service does not allows to exploit CAAM capabilities
hence we need to create a new key_type. The new key type "caam_tk"

allows to:

quoted

 - Create a black key from random
 - Create a black key from a red key
 - Load a black blob to retrieve the black key

On 2018-07-23, Udit Agarwal [off-list ref] sent a series which
seems related to this:
[PATCH v2 1/2] security/keys/secure_key: Adds the secure key support based
on CAAM.
[PATCH v2 2/2] encrypted_keys: Adds support for secure key-type as master
key.

Is this series intended to continue that work and cover the same uses- cases?

If I remember correctly, the CAAM also supports marking blobs to allow or
disallow exporting the encapsulated key from the hardware. Or is this
unneeded and we could encrypt/decrypt other (less critical) key material
against the tk(cbc(aes)) CAAM key via the keyring mechanisms?

Best regards,
Jan
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Hello Jan,

The current series is aimed to change which key type is acceptable in dm-crypt. Without
this change, the key type cannot be integrated properly.

About the key type implementation:
The implementation of the key type is an improvement related to the work of Udit Agarwal.

The transform tk(cbc(aes)) is intended to receive key material whose format can change
hence the "tagging" to handle it properly. It could, for example, handle plain keys, black keys or blobs as key material and this material would be stored in keyring.

Regards,
Franck