[v7,08/10] tpm: Proxy driver for supporting multiple emulated TPMs

Commit Message

Stefan Berger March 12, 2016, 11:27 p.m. UTC

Jarkko Sakkinen <[e-mail]> wrote on 03/12/2016 
01:51:54 PM:

> 
> On Fri, Mar 11, 2016 at 09:51:03PM -0500, 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.
> 
> With my test script [1] running on QEMU and TPM 2.0 simulator running on 
the
> host side I get this:
> 
> $ python tpm2-simulator-vtpm --host=10.0.2.2
> cmd
> 80 01 00 00 00 0c 00 00 01 44 00 00
> rsp
> 80 01 00 00 00 0a 00 00 00 00
> Traceback (most recent call last):
>   File "tpm2-simulator-vtpm", line 85, in <module>
>     main()
>   File "tpm2-simulator-vtpm", line 80, in main
>     resp = client.send_cmd(stream)
>   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 454, in send_cmd
>     rsp = self.simulator.send_cmd(cmd)
>   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 436, in send_cmd
>     raise SimulatorError("Empty response")
> tpm2.SimulatorError: Empty response
> 
> However, the process does not exit before the read call expires:
> 
> $ python tpm2-list-handles
> Traceback (most recent call last):
>   File "tpm2-list-handles", line 61, in <module>
>     main()
>   File "tpm2-list-handles", line 51, in main
>     handles += client.get_cap(tpm2.TPM2_CAP_HANDLES, 
tpm2.HR_LOADED_SESSION)
>   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 782, in get_cap
>     next_handles, more_data = self.__get_cap_cnt(cap, pt, 1)
>   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 766, in __get_cap_cnt
>     rsp = self.send_cmd(cmd)[10:]
>   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 458, in send_cmd
>     rsp = f.read()
> IOError: [Errno 62] Timer expired
> 
> The server side stays stuck unti this happens.

This fix should solve the problem:


Can you let me know whether this gets it working for you? I'd prepare a 
v9.

   Stefan
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Patch

diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c 
b/drivers/char/tpm/tpm_vtpm_proxy.c
index d73944e..01e5070 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -456,10 +456,10 @@  err_delete_proxy_dev:
  */
 static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
 {
-       tpm_chip_unregister(proxy_dev->chip);
-
        vtpm_proxy_fops_undo_open(proxy_dev);

+       tpm_chip_unregister(proxy_dev->chip);
+
        vtpm_proxy_delete_proxy_dev(proxy_dev);
 }