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

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 04/17/2017 11:19 AM, Stefan Berger wrote:
> Add an ioctl to request that the locality be prepended to every TPM
> command.
>
> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> ---
>   drivers/char/tpm/tpm_vtpm_proxy.c | 16 ++++++++++++----
>   include/uapi/linux/vtpm_proxy.h   |  4 +++-
>   2 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
> index bf59426..5f34973 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;
> +	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;

There 'return' statement of this function needs to say 'return len + 
offset'. So I'll resubmit a V2 for that.

Apart from that, any comments?

    Stefan

>
> 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,
>   };
>
>   /**