linux-kernel - Re: [PATCH v4 2/2] tpm: vtpm_proxy: Implement request

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Message-Id: <17af34d3-e07e-8865-0026-ec3e4994a7aa@linux.vnet.ibm.com>
Date:   Mon, 15 May 2017 11:56:51 -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,
        jgunthorpe@...idianresearch.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] tpm: vtpm_proxy: Implement request_locality
 function.

On 05/15/2017 08:41 AM, Jarkko Sakkinen wrote:
> On Wed, May 10, 2017 at 07:54:22PM -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.
>>
>> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>> ---
>>   drivers/char/tpm/tpm.h            |  1 +
>>   drivers/char/tpm/tpm_vtpm_proxy.c | 34 ++++++++++++++++++++++++++++++++++
>>   include/uapi/linux/vtpm_proxy.h   |  5 +++++
>>   3 files changed, 40 insertions(+)
>>
>> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
>> index 4b4c8de..10f0467 100644
>> --- a/drivers/char/tpm/tpm.h
>> +++ b/drivers/char/tpm/tpm.h
>> @@ -527,6 +527,7 @@ enum tpm_transmit_flags {
>>   	TPM_TRANSMIT_UNLOCKED	= BIT(0),
>>   };
>>   
>> +ssize_t tpm_transfer(struct tpm_chip *chip, u8 *buf, u32 count, size_t bufsiz);
>>   ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
>>   		     u8 *buf, size_t bufsiz, unsigned int flags);
>>   ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
>> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
>> index 751059d..374c4ff 100644
>> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
>> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
>> @@ -371,6 +371,39 @@ 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);
>> +	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_transfer(chip, buf.data, tpm_buf_length(&buf), PAGE_SIZE);
>> +	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 +413,7 @@ 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..6b91c2c 100644
>> --- a/include/uapi/linux/vtpm_proxy.h
>> +++ b/include/uapi/linux/vtpm_proxy.h
>> @@ -46,4 +46,9 @@ 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
> This is a question.
>
> Did you have some kind of big idea with 0x20? I was just thinking
> that one way to do this would to allocate starting from 0xFFFFFFFF.

Not quite. Per TPM 1.2 and TPM 2 specs we should operate here with 
Vendor specific commands and they are identified by bit 29.

Check section 17 'Ordinals': 
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Main-Part-2-TPM-Structures_v1.2_rev116_01032011.pdf

Check section 8.9 TPMA_CC: 
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-2-Structures-01.38.pdf

If anything was the 'big idea' then it was the offset '0x1000' :-)

    Stefan