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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: David Howells <dhowells@redhat.com>, Udit Agarwal <udit.agarwal@nxp.com>
Cc: zohar@linux.vnet.ibm.com, jmorris@namei.org, serge@hallyn.com,
	denkenz@gmail.com, linux-integrity@vger.kernel.org,
	keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, sahil.malhotra@nxp.com,
	ruchika.gupta@nxp.com, horia.geanta@nxp.com,
	aymen.sghaier@nxp.com
Subject: Re: [PATCH v2 1/2] security/keys/secure_key: Adds the secure key support based on CAAM.
Date: Thu, 02 Aug 2018 11:57:41 -0700
Message-ID: <1533236261.12916.5.camel@HansenPartnership.com> (raw)
In-Reply-To: <8060.1533226481@warthog.procyon.org.uk>

On Thu, 2018-08-02 at 17:14 +0100, David Howells wrote:
> Udit Agarwal <udit.agarwal@nxp.com> wrote:
> 
> > +==========
> > +Secure Key
> > +==========
> > +
> > +Secure key is the new type added to kernel key ring service.
> > +Secure key is a symmetric type key of minimum length 32 bytes
> > +and with maximum possible length to be 128 bytes. It is produced
> > +in kernel using the CAAM crypto engine. Userspace can only see
> > +the blob for the corresponding key. All the blobs are displayed
> > +or loaded in hex ascii.
> 
> To echo Mimi, this sounds suspiciously like it should have a generic
> interface, not one that's specifically tied to one piece of hardware
> -
> particularly if it's named with generic "secure".
> 
> Can you convert this into a "symmetric" type and make the backend
> pluggable?

This is a symmetric key backed by a piece of hardware, which is exactly
what trusted keys are, so if we're defining common infrastructure with
callouts, trusted keys should be part of it.

Additionally, when I look at the trusted key code, I have significant
qualms about using the TPM RNG exclusively in the same way CAAM wants
to use its own RNG.  What I think both should be doing is collecting
data from their local RNGs, mixing it into the kernel entropy pool and
using a kernel generated random number (just in case these RNGs
suddenly turn out to be less random than they should be).

James



  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-23 11:14 Udit Agarwal
2018-07-23 11:14 ` [PATCH v2 2/2] encrypted_keys: Adds support for secure key-type as master key Udit Agarwal
2018-08-02 16:14 ` [PATCH v2 1/2] security/keys/secure_key: Adds the secure key support based on CAAM David Howells
2018-08-02 18:57   ` James Bottomley [this message]
2018-08-03 11:58   ` Mimi Zohar
2018-08-03 14:23     ` James Bottomley
2018-08-03 14:45       ` Mimi Zohar
2018-08-03 15:48         ` James Bottomley
2018-08-03 18:28           ` Mimi Zohar
2018-10-16 10:16             ` David Gstir
2018-08-03 14:55       ` David Howells
2018-08-03 15:23         ` Mimi Zohar

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