For some TPM commands it is necessary that a TPM emulator knows the
locality in which the command is executed. To support conveying the
locality to the emulator, we implement a flag
VTPM_PROXY_FLAG_PREPEND_LOCALITY for the vtpm_proxy driver's
VTPM_PROXY_IOC_NEW_DEV ioctl to request that the locality be prepended
to every TPM command. This flag is also set in the
VTPM_PROXY_IOC_GET_SUPT_FLAGS ioctl's flags field to indicate that this
feature is supported in this version of the driver.

Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com>
---
 drivers/char/tpm/tpm_vtpm_proxy.c | 18 ++++++++++++++----
 include/uapi/linux/vtpm_proxy.h   |  6 ++++--
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c 
b/drivers/char/tpm/tpm_vtpm_proxy.c
index 48b9818..e45dd33 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;
 
@@ -78,7 +79,10 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char 
__user *buf,
 {
        struct proxy_dev *proxy_dev = filp->private_data;
        size_t len;
-       int sig, rc;
+       int sig;
+       int rc = 0;
+       size_t offset = 0;
+       uint8_t locality;
 
        sig = wait_event_interruptible(proxy_dev->wq,
                proxy_dev->req_len != 0 ||
@@ -102,7 +106,13 @@ 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 +124,7 @@ 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..ce76f0c 100644
--- a/include/uapi/linux/vtpm_proxy.h
+++ b/include/uapi/linux/vtpm_proxy.h
@@ -21,10 +21,12 @@
 
 /**
  * enum vtpm_proxy_flags - flags for the proxy TPM
- * @VTPM_PROXY_FLAG_TPM2:      the proxy TPM uses TPM 2.0 protocol
+ * @VTPM_PROXY_FLAG_TPM2:              the proxy TPM uses TPM 2.0 protocol
+ * @VTPM_PROXY_FLAG_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


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