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

[Stefan Berger]

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@xxxxxxxxxxxxxxxxxx>
> > ---
> >   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