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

[Rajiv Andrade]

Hi Christophe,

On 01/10/2010, at 12:44, Christophe Henri RICARD wrote:

> 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 .
> 

Trousers supports both methods, device read/write or through ioctl, the warning just notifies that the second isn't going to be used due the device driver's lack of support.

> 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).

Sounds like an issue, thanks for reporting, I'll double check/debug this.

> 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.

As long as it implies in occurring a full power cycle, it isn't a TPM problem.

> 
> 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.
> 

I'm using this one as security-next:
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/jamesm-security-next.git

Thanks,
Rajiv

> 
> 
> -----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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