lkml.org 
[lkml]   [2017]   [Oct]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/3] tpm: retrieve digest size of unknown algorithms from TPM
Hi

And apologies for late review.

On Mon, Sep 25, 2017 at 01:19:47PM +0200, Roberto Sassu wrote:
> This patch set derives from a larger patch set which modifies the TPM
> driver API in order to extend a PCR with multiple digests. It can be
> retrieved at the URL:
>
> https://sourceforge.net/p/tpmdd/mailman/message/35905412/

A patch set should be able to live on its own. Please remove this link.

I don't care about that patch set at this point and I'm not going to
give any distant promises.

> The TPM driver currently relies on the crypto subsystem to determine the
> digest size of supported TPM algorithms. In the future, TPM vendors might
> implement new algorithms in their chips, and those algorithms might not
> be supported by the crypto subsystem.
>
> Usually, vendors provide patches for the new hardware, and likely
> the crypto subsystem will be updated before the new algorithm is
> introduced. However, old kernels might be updated later, after patches
> are included in the mainline kernel. This would leave the opportunity
> for attackers to misuse PCRs, as PCR banks with an unknown algorithm
> are not extended.
>
> This patch set provides a long term solution for this issue. If a TPM
> algorithm is not known by the crypto subsystem, the TPM driver retrieves
> the digest size from the TPM with a PCR read. All the PCR banks are
> extended, even if the algorithm is not yet supported by the crypto
> subsystem.

This part makes sense to me.

/Jarkko

\
 
 \ /
  Last update: 2017-10-04 09:33    [W:0.188 / U:0.836 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site