Re: [PATCH v8 08/10] tpm: Proxy driver for supporting multiple emulated TPMs

[Stefan Berger]

On 03/16/2016 08:09 AM, Jarkko Sakkinen wrote:
> On Sun, Mar 13, 2016 at 06:54:38PM -0400, Stefan Berger wrote:
> > This patch implements a proxy driver for supporting multiple emulated TPMs
> > in a system.
> >
> > The driver implements a device /dev/vtpmx that is used to created
> > a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side that
> > is accessed using a file descriptor returned by an ioctl.
> > The device /dev/tpmX is the usual TPM device created by the core TPM
> > driver. Applications or kernel subsystems can send TPM commands to it
> > and the corresponding server-side file descriptor receives these
> > commands and delivers them to an emulated TPM.
> >
> > Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
> > CC: linux-kernel@xxxxxxxxxxxxxxx
> > CC: linux-doc@xxxxxxxxxxxxxxx
> > CC: linux-api@xxxxxxxxxxxxxxx
> Alternative to this would be to have /dev/vtpmx create:
>
> * /dev/vtpm0 for the server
> * /dev/tpm0 for the client
>
> This is how David Howell's PoC worked and that's why I want
> to make this alternative visible.

My initial implementation had this as well.

> The server could even respawn without container noticing it.
> This solution have better availability properties.

A TPM should be stable enough to not have to be respawned...

    Stefan