Re: [PATCH 02/23] TPM: Provide a facility for a userspace TPM emulator

On Tue, Aug 21, 2018 at 12:31:40PM -0600, Jason Gunthorpe wrote:
> On Tue, Aug 21, 2018 at 04:57:03PM +0100, David Howells wrote:
> > Provide a misc device file (/dev/tpm_emul) by which a userspace TPM emulator
> > can set up a virtual TPM device under the control of the TPM frontend.  The
> > way this works is:
> > 
> >  (1) The emulator opens /dev/tpm_emul which is provided by the tpm_user
> >      driver.
> > 
> >  (2) tpm_user registers a TPM device and the tpm driver creates a /dev/tpmN
> >      misc device for the trousers package and suchlike to access.
> > 
> >  (3) The emulator sits in read() on the emulator device waiting for a command
> >      to come through.
> > 
> >  (4) tpm_user passes requests from /dev/tpmN to the emulator's read() call.
> > 
> >  (5) The emulator processes the request.
> > 
> >  (6) The emulator either write()'s the reply or calls ioctl(fd,0,0) to cancel
> >      the command.
> > 
> >  (7) The emulator goes back to read() to wait for the next command.
> > 
> >  (8) tpm_user passes the reply back to the tpm driver which passes it back to
> >      /dev/tpmN.
> > 
> > When the emulator closes /dev/tpm_emul, the TPM driver is unregistered and the
> > /dev/tpmN misc device is then removed.  Any outstanding requests are aborted
> > and -EIO will be returned from then on.  Multiple TPMs can be registered.
> > 
> > Signed-off-by: David Howells <[email protected]>
> > ---
> > 
> >  drivers/char/tpm/Kconfig         |   13 +
> >  drivers/char/tpm/Makefile        |    1 
> >  drivers/char/tpm/tpm_user_emul.c |  672 ++++++++++++++++++++++++++++++++++++++
> >  include/linux/wait.h             |   11 +
> >  4 files changed, 697 insertions(+)
> >  create mode 100644 drivers/char/tpm/tpm_user_emul.c
> 
> This looks to duplicate the vtpm stuff...

Yeah, this is a duplicate to tpm_vtpm_proxy.

> 
> Jason

/Jarkko


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