[PATCH v3 3/3] tpm: vtpm_proxy: Add flag for ioctl to request locality prepended to command

From: Stefan Berger
Date: Thu May 04 2017 - 10:57:03 EST


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 <stefanb@xxxxxxxxxxxxxxxxxx>
---
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