linux-kernel - Re: [PATCH v2 3/3] tpm: vtpm_proxy: Add ioctl to request locality prepended to command

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Message-Id: <40cd7d48-f6d1-39f4-99a3-916c7cdbb636@linux.vnet.ibm.com>
Date:   Wed, 3 May 2017 19:40:48 -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 v2 3/3] tpm: vtpm_proxy: Add ioctl to request locality
 prepended to command

On 05/03/2017 06:37 PM, Jarkko Sakkinen wrote:
> On Fri, Apr 28, 2017 at 09:02:18AM -0400, Stefan Berger wrote:
>> Add an ioctl to request that the locality be prepended to every TPM
>> command.
> Don't really understand this change. Why locality is prenpended?

Commands can be executed under locality 0-3 and for some commands it is 
important to know which locality a user may have chosen. How else should 
we convey that locality to the TPM emulator ?

> Where is the ioctl declaration in this commit?

My bad, it's a flag that's being added here.

>
>> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>> ---
>>   drivers/char/tpm/tpm_vtpm_proxy.c | 18 +++++++++++++-----
>>   include/uapi/linux/vtpm_proxy.h   |  4 +++-
>>   2 files changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
>> index 48b9818..6c90e02 100644
>> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
>> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
>> @@ -52,7 +52,8 @@ struct proxy_dev {
>>   };
>>   
>>   /* all supported flags */
>> -#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2)
>> +#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2 | \
>> +			       VTPM_PROXY_FLAG_PREPEND_LOCALITY)
>>   
>>   static struct workqueue_struct *workqueue;
>>   
>> @@ -77,8 +78,9 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
>>   				    size_t count, loff_t *off)
>>   {
>>   	struct proxy_dev *proxy_dev = filp->private_data;
>> -	size_t len;
>> -	int sig, rc;
>> +	size_t len, offset = 0;
>> +	int sig, rc = 0;
> One line per declaration:
>
> size_t len;
> size_t offset = 0;
> int sig;
> int rc = 0;
>
>> +	uint8_t locality;
>>   
>>   	sig = wait_event_interruptible(proxy_dev->wq,
>>   		proxy_dev->req_len != 0 ||
>> @@ -102,7 +104,13 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
>>   		return -EIO;
>>   	}
>>   
>> -	rc = copy_to_user(buf, proxy_dev->buffer, len);
>> +	if (proxy_dev->flags & VTPM_PROXY_FLAG_PREPEND_LOCALITY) {
>> +		locality = proxy_dev->chip->locality;
>> +		offset = sizeof(locality);
>> +		rc = copy_to_user(buf, &locality, offset);
>> +	}
>> +	if (!rc)
>> +		rc = copy_to_user(&buf[offset], proxy_dev->buffer, len);
>>   	memset(proxy_dev->buffer, 0, len);
>>   	proxy_dev->req_len = 0;
>>   
>> @@ -114,7 +122,7 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
>>   	if (rc)
>>   		return -EFAULT;
>>   
>> -	return len;
>> +	return offset + len;
>>   }
>>   
>>   /**
>> diff --git a/include/uapi/linux/vtpm_proxy.h b/include/uapi/linux/vtpm_proxy.h
>> index 83e64e7..512a29e 100644
>> --- a/include/uapi/linux/vtpm_proxy.h
>> +++ b/include/uapi/linux/vtpm_proxy.h
>> @@ -22,9 +22,11 @@
>>   /**
>>    * enum vtpm_proxy_flags - flags for the proxy TPM
>>    * @VTPM_PROXY_FLAG_TPM2:	the proxy TPM uses TPM 2.0 protocol
>> + * @VTPM_PROXY_PREPEND_LOCALITY:locality byte prepended on each command
>>    */
>>   enum vtpm_proxy_flags {
>> -	VTPM_PROXY_FLAG_TPM2	= 1,
>> +	VTPM_PROXY_FLAG_TPM2			= 1,
>> +	VTPM_PROXY_FLAG_PREPEND_LOCALITY	= 2,
>>   };
>>   
>>   /**
>> -- 
>> 2.4.3
>>
> /Jarkko
>