RE: [PATCH 1/3] TPM: new stm i2c device driver

[Christophe Henri RICARD]

Hi Rajiv,

I had implemented the ioctl function with TPMIOC_CANCEL/TPMIOC_TRANSMIT because I have seen that when I was trying to run a TSS tcsd(trousers) process some errors or warning messages were displayed.
I have just checked the trousers source code I have and it use this way in src/tddl/tddl.c .

For your information also, the 2 buffers tpm_i2c_buffer instead of the data buffer in my driver was because I found what I suppose to be an error with the allocation of chip->data_buffer in the tpm_open function.
When I have done the following test with the tpm_tis driver for example on a pc platform (x86) with a TPM:
- No TPM application launch such as TSS (trousers).
- Put the platform in standby
- Wake up the platform
dmesg will shows an error during suspend/resume functions execution.
My understanding is that in that specific case, no buffer is allocated and the driver couldn't save the TPM context (TPM_SaveState).
In the case the platform generate a RESET on the LPC bus or on the TPM during standby all the TPM volatile context will be cleared 
(all the PCR's for example). I think this could be a problem.

Only for my information, I would like to know if this scenario (TPM RESET during standby) could happen and if it could be a TPM/security issue.

I suppose what you are calling security-next tree is linux-next tree on www.kernel.org or are you referring to another tree ?
I will try to provide you a patch for the ioctl function asap.

Thanks.
Christophe

-----Original Message-----
From: Rajiv Andrade [mailto:srajiv@xxxxxxxxxxxxxxxxxx] 
Sent: Friday, October 01, 2010 10:26 AM
To: Christophe Henri RICARD
Cc: James Morris; linux-kernel@xxxxxxxxxxxxxxx; joe@xxxxxxxxxxx
Subject: Re: [PATCH 1/3] TPM: new stm i2c device driver

Hi Christophe,

The code must be applied and compiled against the security-next tree, that currently doesn't provide the locked ioctl anymore. Can you implement the locking inside tpm_st19_i2c_ioctl() and set it at the unlocked_ioctl field? Shouldn't be too hard, you can get tpm_write() as an example.

By the way, I may be missing something, but why the tpm command transmission (TPMIOC_TRANSMIT) should be handled through ioctl instead of a modified tpm_write() that can send the commands through i2c?

Thanks,
Rajiv

On 01/10/2010, at 11:27, Christophe Henri RICARD wrote:

> Hi James,
> 
> Which kernel are you using ?
> I have made my testing with a 2.6.35.4 kernel.
> As far as I know kernel 2.6.36 will not provide any ioctl field any more.
> May be this is the reason ?
> 
> Please let me know.
> Thanks
> Christophe
> 
> -----Original Message-----
> From: James Morris [mailto:jmorris@xxxxxxxxx] 
> Sent: Thursday, September 30, 2010 7:51 PM
> To: Rajiv Andrade
> Cc: linux-kernel@xxxxxxxxxxxxxxx; joe@xxxxxxxxxxx; Christophe Henri RICARD
> Subject: Re: [PATCH 1/3] TPM: new stm i2c device driver
> 
> On Thu, 30 Sep 2010, Rajiv Andrade wrote:
> 
>> From: Christophe Henri RICARD <christophe-h.ricard@xxxxxx>
>> 
>> This driver uses the Linux I2C, TPM and generic gpio interfaces.
>> 
>> Signed-off-by: Christophe Henri RICARD <christophe-h.ricard@xxxxxx>
>> Signed-off-by: Rajiv Andrade <srajiv@xxxxxxxxxxxxxxxxxx>
> 
> This does not look to have been compile tested against my tree:
> 
> CC [M]  drivers/char/tpm/tpm_stm_st19_i2c.o
> drivers/char/tpm/tpm_stm_st19_i2c.c:574: error: unknown field ioctl specified in initializer
> drivers/char/tpm/tpm_stm_st19_i2c.c:574: warning: initialization from incompatible pointer type
> make[1]: *** [drivers/char/tpm/tpm_stm_st19_i2c.o] Error 1
> 
> The locked ioctl was removed in commit
> b19dd42faf413b4705d4adb38521e82d73fa4249
> 
> 
> 
> - James
> -- 
> James Morris
> <jmorris@xxxxxxxxx>
> --
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