linux-kernel - Re: [PATCH v6 2/3] tpm: vtpm_proxy: Implement request

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Date:   Thu, 1 Jun 2017 20:34:31 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     tpmdd-devel@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, jgunthorpe@...idianresearch.com
Subject: Re: [PATCH v6 2/3] tpm: vtpm_proxy: Implement request_locality
 function.

On 05/24/2017 08:09 PM, Jarkko Sakkinen wrote:
> On Wed, May 24, 2017 at 07:03:27PM -0400, Stefan Berger wrote:
>> On 05/24/2017 06:21 PM, Jarkko Sakkinen wrote:
>>> On Wed, May 24, 2017 at 05:39:40PM -0400, Stefan Berger wrote:
>>>> Implement the request_locality function. To set the locality on the
>>>> backend we define vendor-specific TPM 1.2 and TPM 2 ordinals and send
>>>> a command to the backend to set the locality for the next commands.
>>>>
>>>> To avoid recursing into requesting the locality, we set the
>>>> TPM_TRANSMIT_RAW flag when calling tpm_transmit_cmd. To avoid recursing
>>>> into TPM 2 space related commands, we set the space parameter to NULL.
>>>>
>>>> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>>>> ---
>>>>    drivers/char/tpm/tpm-interface.c  |  1 +
>>>>    drivers/char/tpm/tpm_vtpm_proxy.c | 36 ++++++++++++++++++++++++++++++++++++
>>>>    include/uapi/linux/vtpm_proxy.h   |  4 ++++
>>>>    3 files changed, 41 insertions(+)
>>>>
>>>> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
>>>> index 2eacda2..876d45f 100644
>>>> --- a/drivers/char/tpm/tpm-interface.c
>>>> +++ b/drivers/char/tpm/tpm-interface.c
>>>> @@ -537,6 +537,7 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
>>>>    	return 0;
>>>>    }
>>>> +EXPORT_SYMBOL_GPL(tpm_transmit_cmd);
>>>>    #define TPM_DIGEST_SIZE 20
>>>>    #define TPM_RET_CODE_IDX 6
>>>> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
>>>> index 751059d..66024bf 100644
>>>> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
>>>> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
>>>> @@ -371,6 +371,41 @@ static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
>>>>    	return ret;
>>>>    }
>>>> +static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
>>>> +{
>>>> +	struct tpm_buf buf;
>>>> +	int rc;
>>>> +	const struct tpm_output_header *header;
>>>> +
>>>> +	if (chip->flags & TPM_CHIP_FLAG_TPM2)
>>>> +		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
>>>> +				  TPM2_CC_SET_LOCALITY);
>>> I would always go with this branch.
>>>
>>>> +	else
>>>> +		rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
>>>> +				  TPM_ORD_SET_LOCALITY);
>>>> +	if (rc)
>>>> +		return rc;
>>>> +	tpm_buf_append_u8(&buf, locality);
>>>> +
>>>> +	rc = tpm_transmit_cmd(chip, NULL, buf.data, tpm_buf_length(&buf), 0,
>>>> +			      TPM_TRANSMIT_UNLOCKED | TPM_TRANSMIT_RAW,
>>>> +			      "attempting to set locality");
>>>> +	if (rc < 0) {
>>>> +		locality = rc;
>>>> +		goto out;
>>>> +	}
>>>> +
>>>> +	header = (const struct tpm_output_header *)buf.data;
>>>> +	rc = be32_to_cpu(header->return_code);
>>>> +	if (rc)
>>>> +		locality = -1;
>>>> +
>>>> +out:
>>>> +	tpm_buf_destroy(&buf);
>>>> +
>>>> +	return locality;
>>>> +}
>>>> +
>>>>    static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
>>>>    	.flags = TPM_OPS_AUTO_STARTUP,
>>>>    	.recv = vtpm_proxy_tpm_op_recv,
>>>> @@ -380,6 +415,7 @@ static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
>>>>    	.req_complete_mask = VTPM_PROXY_REQ_COMPLETE_FLAG,
>>>>    	.req_complete_val = VTPM_PROXY_REQ_COMPLETE_FLAG,
>>>>    	.req_canceled = vtpm_proxy_tpm_req_canceled,
>>>> +	.request_locality = vtpm_proxy_request_locality,
>>>>    };
>>>>    /*
>>>> diff --git a/include/uapi/linux/vtpm_proxy.h b/include/uapi/linux/vtpm_proxy.h
>>>> index a69e991..58ac73c 100644
>>>> --- a/include/uapi/linux/vtpm_proxy.h
>>>> +++ b/include/uapi/linux/vtpm_proxy.h
>>>> @@ -46,4 +46,8 @@ struct vtpm_proxy_new_dev {
>>>>    #define VTPM_PROXY_IOC_NEW_DEV	_IOWR(0xa1, 0x00, struct vtpm_proxy_new_dev)
>>>> +/* vendor specific commands to set locality */
>>>> +#define TPM2_CC_SET_LOCALITY	0x20001000
>>>> +#define TPM_ORD_SET_LOCALITY	0x20001000
>>>> +
>>>>    #endif /* _UAPI_LINUX_VTPM_PROXY_H */
>>>> -- 
>>>> 2.4.3
>>> What practical benefit you get from these two constants? I understand
>>> the value range but not so much the redundant code.
>> If you want to change this, please go ahead and give it a sinle name.
>> For the code branches above I think that we should at least send a TPM 1.2
>> formatted command in case of TPM 1.2 and a TPM 2 formatted one in case of
>> TPM 2. It seems just 'proper.'
>>
>>     Stefan
> Agreed. I will make these changes no need to send new series.

I pushed an update to the test suite, which may help the cause to accept 
this series.

https://github.com/stefanberger/linux-vtpm-tests

Patch 3/3 should probably not return -EFAULT in case of the user trying 
to send the SetLocality command via /dev/tpm%d but rather -EPIPE to get 
the logging of the error suppressed, even though that doesn't seem to be 
the right error code.


   Stefan

>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>
> /Jarkko
>