[tpmdd-devel,v7,08/10] tpm: Proxy driver for supporting multiple emulated TPMs
diff mbox

Message ID 1457751065-11507-9-git-send-email-stefanb@linux.vnet.ibm.com
State New
Headers show

Commit Message

Stefan Berger March 12, 2016, 2:51 a.m. UTC
This patch implements a proxy driver for supporting multiple emulated TPMs
in a system.

The driver implements a device /dev/vtpmx that is used to created
a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side that
is accessed using a file descriptor returned by an ioctl.
The device /dev/tpmX is the usual TPM device created by the core TPM
driver. Applications or kernel subsystems can send TPM commands to it
and the corresponding server-side file descriptor receives these
commands and delivers them to an emulated TPM.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
CC: linux-kernel@vger.kernel.org
CC: linux-doc@vger.kernel.org
CC: linux-api@vger.kernel.org
---
 drivers/char/tpm/Kconfig          |  10 +
 drivers/char/tpm/Makefile         |   1 +
 drivers/char/tpm/tpm_vtpm_proxy.c | 567 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild         |   1 +
 include/uapi/linux/vtpm_proxy.h   |  42 +++
 5 files changed, 621 insertions(+)
 create mode 100644 drivers/char/tpm/tpm_vtpm_proxy.c
 create mode 100644 include/uapi/linux/vtpm_proxy.h

Comments

Jarkko Sakkinen March 12, 2016, 6:51 p.m. UTC | #1
On Fri, Mar 11, 2016 at 09:51:03PM -0500, Stefan Berger wrote:
> This patch implements a proxy driver for supporting multiple emulated TPMs
> in a system.
> 
> The driver implements a device /dev/vtpmx that is used to created
> a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side that
> is accessed using a file descriptor returned by an ioctl.
> The device /dev/tpmX is the usual TPM device created by the core TPM
> driver. Applications or kernel subsystems can send TPM commands to it
> and the corresponding server-side file descriptor receives these
> commands and delivers them to an emulated TPM.

With my test script [1] running on QEMU and TPM 2.0 simulator running on the
host side I get this:

$ python tpm2-simulator-vtpm --host=10.0.2.2
cmd
80 01 00 00 00 0c 00 00 01 44 00 00
rsp
80 01 00 00 00 0a 00 00 00 00
Traceback (most recent call last):
  File "tpm2-simulator-vtpm", line 85, in <module>
    main()
  File "tpm2-simulator-vtpm", line 80, in main
    resp = client.send_cmd(stream)
  File "/home/tpmdd/tpm2-scripts/tpm2.py", line 454, in send_cmd
    rsp = self.simulator.send_cmd(cmd)
  File "/home/tpmdd/tpm2-scripts/tpm2.py", line 436, in send_cmd
    raise SimulatorError("Empty response")
tpm2.SimulatorError: Empty response

However, the process does not exit before the read call expires:

$ python tpm2-list-handles
Traceback (most recent call last):
  File "tpm2-list-handles", line 61, in <module>
    main()
  File "tpm2-list-handles", line 51, in main
    handles += client.get_cap(tpm2.TPM2_CAP_HANDLES, tpm2.HR_LOADED_SESSION)
  File "/home/tpmdd/tpm2-scripts/tpm2.py", line 782, in get_cap
    next_handles, more_data = self.__get_cap_cnt(cap, pt, 1)
  File "/home/tpmdd/tpm2-scripts/tpm2.py", line 766, in __get_cap_cnt
    rsp = self.send_cmd(cmd)[10:]
  File "/home/tpmdd/tpm2-scripts/tpm2.py", line 458, in send_cmd
    rsp = f.read()
IOError: [Errno 62] Timer expired

The server side stays stuck unti this happens.

[1] git://git.infradead.org/users/jjs/tpm2-scripts.git

/Jarkko

> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> CC: linux-kernel@vger.kernel.org
> CC: linux-doc@vger.kernel.org
> CC: linux-api@vger.kernel.org
> ---
>  drivers/char/tpm/Kconfig          |  10 +
>  drivers/char/tpm/Makefile         |   1 +
>  drivers/char/tpm/tpm_vtpm_proxy.c | 567 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/Kbuild         |   1 +
>  include/uapi/linux/vtpm_proxy.h   |  42 +++
>  5 files changed, 621 insertions(+)
>  create mode 100644 drivers/char/tpm/tpm_vtpm_proxy.c
>  create mode 100644 include/uapi/linux/vtpm_proxy.h
> 
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 3b84a8b..0eac596 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -122,5 +122,15 @@ config TCG_CRB
>  	  from within Linux.  To compile this driver as a module, choose
>  	  M here; the module will be called tpm_crb.
>  
> +config TCG_VTPM_PROXY
> +	tristate "VTPM Proxy Interface"
> +	depends on TCG_TPM
> +	---help---
> +	  This driver proxies for an emulated TPM (vTPM) running in userspace.
> +	  A device /dev/vtpmx is provided that creates a device pair
> +	  /dev/vtpmX and a server-side file descriptor on which the vTPM
> +	  can receive commands.
> +
> +
>  source "drivers/char/tpm/st33zp24/Kconfig"
>  endif # TCG_TPM
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 56e8f1f..98de5e6 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -23,3 +23,4 @@ obj-$(CONFIG_TCG_IBMVTPM) += tpm_ibmvtpm.o
>  obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/
>  obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
>  obj-$(CONFIG_TCG_CRB) += tpm_crb.o
> +obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
> new file mode 100644
> index 0000000..d73944e
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
> @@ -0,0 +1,567 @@
> +/*
> + * Copyright (C) 2015, 2016 IBM Corporation
> + *
> + * Author: Stefan Berger <stefanb@us.ibm.com>
> + *
> + * Maintained by: <tpmdd-devel@lists.sourceforge.net>
> + *
> + * Device driver for vTPM (vTPM proxy driver)
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2 of the
> + * License.
> + *
> + */
> +
> +#include <linux/types.h>
> +#include <linux/spinlock.h>
> +#include <linux/uaccess.h>
> +#include <linux/wait.h>
> +#include <linux/miscdevice.h>
> +#include <linux/vtpm_proxy.h>
> +#include <linux/file.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/poll.h>
> +#include <linux/compat.h>
> +
> +#include "tpm.h"
> +
> +#define VTPM_PROXY_REQ_COMPLETE_FLAG  BIT(0)
> +
> +struct proxy_dev {
> +	struct tpm_chip *chip;
> +
> +	u32 flags;                   /* public API flags */
> +
> +	wait_queue_head_t wq;
> +
> +	struct mutex buf_lock;       /* protect buffer and flags */
> +
> +	long state;                  /* internal state */
> +#define STATE_OPENED_FLAG        BIT(0)
> +#define STATE_WAIT_RESPONSE_FLAG BIT(1)  /* waiting for emulator response */
> +
> +	size_t req_len;              /* length of queued TPM request */
> +	size_t resp_len;             /* length of queued TPM response */
> +	u8 buffer[TPM_BUFSIZE];      /* request/response buffer */
> +};
> +
> +
> +static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev);
> +
> +/*
> + * Functions related to 'server side'
> + */
> +
> +/**
> + * vtpm_proxy_fops_read - Read TPM commands on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error code
> + */
> +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;
> +
> +	sig = wait_event_interruptible(proxy_dev->wq, proxy_dev->req_len != 0);
> +	if (sig)
> +		return -EINTR;
> +
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	len = proxy_dev->req_len;
> +
> +	if (count < len) {
> +		mutex_unlock(&proxy_dev->buf_lock);
> +		pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
> +			 count, len);
> +		return -EIO;
> +	}
> +
> +	rc = copy_to_user(buf, proxy_dev->buffer, len);
> +	memset(proxy_dev->buffer, 0, len);
> +	proxy_dev->req_len = 0;
> +
> +	if (!rc)
> +		proxy_dev->state |= STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	if (rc)
> +		return -EFAULT;
> +
> +	return len;
> +}
> +
> +/**
> + * vtpm_proxy_fops_write - Write TPM responses on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error value
> + */
> +static ssize_t vtpm_proxy_fops_write(struct file *filp, const char __user *buf,
> +				     size_t count, loff_t *off)
> +{
> +	struct proxy_dev *proxy_dev = filp->private_data;
> +
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	if (count > sizeof(proxy_dev->buffer) ||
> +	    !(proxy_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
> +		mutex_unlock(&proxy_dev->buf_lock);
> +		return -EIO;
> +	}
> +
> +	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	proxy_dev->req_len = 0;
> +
> +	if (copy_from_user(proxy_dev->buffer, buf, count)) {
> +		mutex_unlock(&proxy_dev->buf_lock);
> +		return -EFAULT;
> +	}
> +
> +	proxy_dev->resp_len = count;
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	wake_up_interruptible(&proxy_dev->wq);
> +
> +	return count;
> +}
> +
> +/*
> + * vtpm_proxy_fops_poll: Poll status on 'server side'
> + *
> + * Return value:
> + *      Poll flags
> + */
> +static unsigned int vtpm_proxy_fops_poll(struct file *filp, poll_table *wait)
> +{
> +	struct proxy_dev *proxy_dev = filp->private_data;
> +	unsigned ret;
> +
> +	poll_wait(filp, &proxy_dev->wq, wait);
> +
> +	ret = POLLOUT;
> +
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	if (proxy_dev->req_len)
> +		ret |= POLLIN | POLLRDNORM;
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * vtpm_proxy_fops_open - Open vTPM device on 'server side'
> + *
> + * Called when setting up the anonymous file descriptor
> + */
> +static void vtpm_proxy_fops_open(struct file *filp)
> +{
> +	struct proxy_dev *proxy_dev = filp->private_data;
> +
> +	proxy_dev->state |= STATE_OPENED_FLAG;
> +}
> +
> +/**
> + * vtpm_proxy_fops_undo_open - counter-part to vtpm_fops_open
> + *
> + * Call to undo vtpm_proxy_fops_open
> + */
> +static void vtpm_proxy_fops_undo_open(struct proxy_dev *proxy_dev)
> +{
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	proxy_dev->state &= ~STATE_OPENED_FLAG;
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	/* no more TPM responses -- wake up anyone waiting for them */
> +	wake_up_interruptible(&proxy_dev->wq);
> +}
> +
> +/*
> + * vtpm_proxy_fops_release: Close 'server side'
> + *
> + * Return value:
> + *      Always returns 0.
> + */
> +static int vtpm_proxy_fops_release(struct inode *inode, struct file *filp)
> +{
> +	struct proxy_dev *proxy_dev = filp->private_data;
> +
> +	filp->private_data = NULL;
> +
> +	vtpm_proxy_delete_device(proxy_dev);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations vtpm_proxy_fops = {
> +	.owner = THIS_MODULE,
> +	.llseek = no_llseek,
> +	.read = vtpm_proxy_fops_read,
> +	.write = vtpm_proxy_fops_write,
> +	.poll = vtpm_proxy_fops_poll,
> +	.release = vtpm_proxy_fops_release,
> +};
> +
> +/*
> + * Functions invoked by the core TPM driver to send TPM commands to
> + * 'server side' and receive responses from there.
> + */
> +
> +/*
> + * Called when core TPM driver reads TPM responses from 'server side'
> + *
> + * Return value:
> + *      Number of TPM response bytes read, negative error value otherwise
> + */
> +static int vtpm_proxy_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct proxy_dev *proxy_dev = chip->vendor.priv;
> +	size_t len;
> +
> +	if (!proxy_dev)
> +		return -EIO;
> +
> +	/* process gone ? */
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&proxy_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	len = proxy_dev->resp_len;
> +	if (count < len) {
> +		dev_err(&chip->dev,
> +			"Invalid size in recv: count=%zd, resp_len=%zd\n",
> +			count, len);
> +		len = -EIO;
> +		goto out;
> +	}
> +
> +	memcpy(buf, proxy_dev->buffer, len);
> +	proxy_dev->resp_len = 0;
> +
> +out:
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	return len;
> +}
> +
> +/*
> + * Called when core TPM driver forwards TPM requests to 'server side'.
> + *
> + * Return value:
> + *      0 in case of success, negative error value otherwise.
> + */
> +static int vtpm_proxy_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct proxy_dev *proxy_dev = chip->vendor.priv;
> +	int rc = 0;
> +
> +	if (!proxy_dev)
> +		return -EIO;
> +
> +	if (count > sizeof(proxy_dev->buffer)) {
> +		dev_err(&chip->dev,
> +			"Invalid size in send: count=%zd, buffer size=%zd\n",
> +			count, sizeof(proxy_dev->buffer));
> +		return -EIO;
> +	}
> +
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&proxy_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	proxy_dev->resp_len = 0;
> +
> +	proxy_dev->req_len = count;
> +	memcpy(proxy_dev->buffer, buf, count);
> +
> +	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	wake_up_interruptible(&proxy_dev->wq);
> +
> +	return rc;
> +}
> +
> +static void vtpm_proxy_tpm_op_cancel(struct tpm_chip *chip)
> +{
> +	/* not supported */
> +}
> +
> +static u8 vtpm_proxy_tpm_op_status(struct tpm_chip *chip)
> +{
> +	struct proxy_dev *proxy_dev = chip->vendor.priv;
> +
> +	if (proxy_dev->resp_len)
> +		return VTPM_PROXY_REQ_COMPLETE_FLAG;
> +
> +	return 0;
> +}
> +
> +static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
> +{
> +	struct proxy_dev *proxy_dev = chip->vendor.priv;
> +	bool ret;
> +
> +	mutex_lock(&proxy_dev->buf_lock);
> +
> +	ret = !(proxy_dev->state & STATE_OPENED_FLAG);
> +
> +	mutex_unlock(&proxy_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
> +	.recv = vtpm_proxy_tpm_op_recv,
> +	.send = vtpm_proxy_tpm_op_send,
> +	.cancel = vtpm_proxy_tpm_op_cancel,
> +	.status = vtpm_proxy_tpm_op_status,
> +	.req_complete_mask = VTPM_PROXY_REQ_COMPLETE_FLAG,
> +	.req_complete_val = VTPM_PROXY_REQ_COMPLETE_FLAG,
> +	.req_canceled = vtpm_proxy_tpm_req_canceled,
> +};
> +
> +/*
> + * Code related to creation and deletion of device pairs
> + */
> +static struct proxy_dev *vtpm_proxy_create_proxy_dev(void)
> +{
> +	struct proxy_dev *proxy_dev;
> +	struct tpm_chip *chip;
> +	int err;
> +
> +	proxy_dev = kzalloc(sizeof(*proxy_dev), GFP_KERNEL);
> +	if (proxy_dev == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	init_waitqueue_head(&proxy_dev->wq);
> +	mutex_init(&proxy_dev->buf_lock);
> +
> +	chip = tpm_chip_alloc(NULL, &vtpm_proxy_tpm_ops);
> +	if (IS_ERR(chip)) {
> +		err = PTR_ERR(chip);
> +		goto err_proxy_dev_free;
> +	}
> +	chip->vendor.priv = proxy_dev;
> +
> +	proxy_dev->chip = chip;
> +
> +	return proxy_dev;
> +
> +err_proxy_dev_free:
> +	kfree(proxy_dev);
> +
> +	return ERR_PTR(err);
> +}
> +
> +/*
> + * Undo what has been done in vtpm_create_proxy_dev
> + */
> +static inline void vtpm_proxy_delete_proxy_dev(struct proxy_dev *proxy_dev)
> +{
> +	put_device(&proxy_dev->chip->dev); /* frees chip */
> +	kfree(proxy_dev);
> +}
> +
> +/*
> + * Create a /dev/tpm%d and 'server side' file descriptor pair
> + *
> + * Return value:
> + *      Returns file pointer on success, an error value otherwise
> + */
> +static struct file *vtpm_proxy_create_device(
> +				 struct vtpm_proxy_new_dev *vtpm_new_dev)
> +{
> +	struct proxy_dev *proxy_dev;
> +	int rc, fd;
> +	struct file *file;
> +
> +	if (vtpm_new_dev->flags & ~VTPM_PROXY_FLAGS_ALL)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	proxy_dev = vtpm_proxy_create_proxy_dev();
> +	if (IS_ERR(proxy_dev))
> +		return ERR_CAST(proxy_dev);
> +
> +	proxy_dev->flags = vtpm_new_dev->flags;
> +
> +	/* setup an anonymous file for the server-side */
> +	fd = get_unused_fd_flags(O_RDWR);
> +	if (fd < 0) {
> +		rc = fd;
> +		goto err_delete_proxy_dev;
> +	}
> +
> +	file = anon_inode_getfile("[vtpms]", &vtpm_proxy_fops, proxy_dev,
> +				  O_RDWR);
> +	if (IS_ERR(file)) {
> +		rc = PTR_ERR(file);
> +		goto err_put_unused_fd;
> +	}
> +
> +	/* from now on we can unwind with put_unused_fd() + fput() */
> +	/* simulate an open() on the server side */
> +	vtpm_proxy_fops_open(file);
> +
> +	if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
> +		proxy_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;
> +
> +	rc = tpm_chip_register(proxy_dev->chip);
> +	if (rc)
> +		goto err_vtpm_fput;
> +
> +	vtpm_new_dev->fd = fd;
> +	vtpm_new_dev->major = MAJOR(proxy_dev->chip->dev.devt);
> +	vtpm_new_dev->minor = MINOR(proxy_dev->chip->dev.devt);
> +	vtpm_new_dev->tpm_num = proxy_dev->chip->dev_num;
> +
> +	return file;
> +
> +err_vtpm_fput:
> +	put_unused_fd(fd);
> +	fput(file);
> +
> +	return ERR_PTR(rc);
> +
> +err_put_unused_fd:
> +	put_unused_fd(fd);
> +
> +err_delete_proxy_dev:
> +	vtpm_proxy_delete_proxy_dev(proxy_dev);
> +
> +	return ERR_PTR(rc);
> +}
> +
> +/*
> + * Counter part to vtpm_create_device.
> + */
> +static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
> +{
> +	tpm_chip_unregister(proxy_dev->chip);
> +
> +	vtpm_proxy_fops_undo_open(proxy_dev);
> +
> +	vtpm_proxy_delete_proxy_dev(proxy_dev);
> +}
> +
> +/*
> + * Code related to the control device /dev/vtpmx
> + */
> +
> +/*
> + * vtpmx_fops_ioctl: ioctl on /dev/vtpmx
> + *
> + * Return value:
> + *      Returns 0 on success, a negative error code otherwise.
> + */
> +static long vtpmx_fops_ioctl(struct file *f, unsigned int ioctl,
> +				   unsigned long arg)
> +{
> +	void __user *argp = (void __user *)arg;
> +	struct vtpm_proxy_new_dev *vtpm_new_dev_p;
> +	struct vtpm_proxy_new_dev vtpm_new_dev;
> +	struct file *file;
> +
> +	switch (ioctl) {
> +	case VTPM_PROXY_IOC_NEW_DEV:
> +		if (!capable(CAP_SYS_ADMIN))
> +			return -EPERM;
> +		vtpm_new_dev_p = argp;
> +		if (copy_from_user(&vtpm_new_dev, vtpm_new_dev_p,
> +				   sizeof(vtpm_new_dev)))
> +			return -EFAULT;
> +		file = vtpm_proxy_create_device(&vtpm_new_dev);
> +		if (IS_ERR(file))
> +			return PTR_ERR(file);
> +		if (copy_to_user(vtpm_new_dev_p, &vtpm_new_dev,
> +				 sizeof(vtpm_new_dev))) {
> +			put_unused_fd(vtpm_new_dev.fd);
> +			fput(file);
> +			return -EFAULT;
> +		}
> +
> +		fd_install(vtpm_new_dev.fd, file);
> +		return 0;
> +
> +	default:
> +		return -ENOIOCTLCMD;
> +	}
> +}
> +
> +#ifdef CONFIG_COMPAT
> +static long vtpmx_fops_compat_ioctl(struct file *f, unsigned int ioctl,
> +					  unsigned long arg)
> +{
> +	return vtpmx_fops_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
> +}
> +#endif
> +
> +static const struct file_operations vtpmx_fops = {
> +	.owner = THIS_MODULE,
> +	.unlocked_ioctl = vtpmx_fops_ioctl,
> +#ifdef CONFIG_COMPAT
> +	.compat_ioctl = vtpmx_fops_compat_ioctl,
> +#endif
> +	.llseek = noop_llseek,
> +};
> +
> +static struct miscdevice vtpmx_miscdev = {
> +	.minor = MISC_DYNAMIC_MINOR,
> +	.name = "vtpmx",
> +	.fops = &vtpmx_fops,
> +};
> +
> +static int vtpmx_init(void)
> +{
> +	return misc_register(&vtpmx_miscdev);
> +}
> +
> +static void vtpmx_cleanup(void)
> +{
> +	misc_deregister(&vtpmx_miscdev);
> +}
> +
> +static int __init vtpm_module_init(void)
> +{
> +	int rc;
> +
> +	rc = vtpmx_init();
> +	if (rc) {
> +		pr_err("couldn't create vtpmx device\n");
> +		return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +static void __exit vtpm_module_exit(void)
> +{
> +	vtpmx_cleanup();
> +}
> +
> +module_init(vtpm_module_init);
> +module_exit(vtpm_module_exit);
> +
> +MODULE_AUTHOR("Stefan Berger (stefanb@us.ibm.com)");
> +MODULE_DESCRIPTION("vTPM Driver");
> +MODULE_VERSION("0.1");
> +MODULE_LICENSE("GPL");
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index ebd10e6..ac767ce 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -449,6 +449,7 @@ header-y += virtio_scsi.h
>  header-y += virtio_types.h
>  header-y += vm_sockets.h
>  header-y += vt.h
> +header-y += vtpm_proxy.h
>  header-y += wait.h
>  header-y += wanrouter.h
>  header-y += watchdog.h
> diff --git a/include/uapi/linux/vtpm_proxy.h b/include/uapi/linux/vtpm_proxy.h
> new file mode 100644
> index 0000000..dc73f00
> --- /dev/null
> +++ b/include/uapi/linux/vtpm_proxy.h
> @@ -0,0 +1,42 @@
> +/*
> + * Definitions for the VTPM proxy driver
> + * Copyright (c) 2015, 2016, IBM Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#ifndef _UAPI_LINUX_VTPM_PROXY_H
> +#define _UAPI_LINUX_VTPM_PROXY_H
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +/* ioctls */
> +
> +struct vtpm_proxy_new_dev {
> +	__u32 flags;         /* input */
> +	__u32 tpm_num;       /* output */
> +	__u32 fd;            /* output */
> +	__u32 major;         /* output */
> +	__u32 minor;         /* output */
> +};
> +
> +/* above flags */
> +#define VTPM_PROXY_FLAG_TPM2  1  /* emulator is TPM 2 */
> +
> +/* all supported flags */
> +#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2)
> +
> +#define VTPM_PROXY_MAGIC 0xa1
> +
> +#define VTPM_PROXY_IOC_NEW_DEV   _IOW(VTPM_PROXY_MAGIC, 0x00, \
> +				      struct vtpm_proxy_new_dev)
> +
> +#endif /* _UAPI_LINUX_VTPM_PROXY_H */
> -- 
> 2.4.3
> 

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Jarkko Sakkinen March 13, 2016, 8:06 p.m. UTC | #2
On Sat, Mar 12, 2016 at 06:27:13PM -0500, Stefan Berger wrote:
>    Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote on 03/12/2016
>    01:51:54 PM:
> 
>    >
>    > On Fri, Mar 11, 2016 at 09:51:03PM -0500, Stefan Berger wrote:
>    > > This patch implements a proxy driver for supporting multiple emulated
>    TPMs
>    > > in a system.
>    > >
>    > > The driver implements a device /dev/vtpmx that is used to created
>    > > a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side
>    that
>    > > is accessed using a file descriptor returned by an ioctl.
>    > > The device /dev/tpmX is the usual TPM device created by the core TPM
>    > > driver. Applications or kernel subsystems can send TPM commands to it
>    > > and the corresponding server-side file descriptor receives these
>    > > commands and delivers them to an emulated TPM.
>    >
>    > With my test script [1] running on QEMU and TPM 2.0 simulator running on
>    the
>    > host side I get this:
>    >
>    > $ python tpm2-simulator-vtpm --host=10.0.2.2
>    > cmd
>    > 80 01 00 00 00 0c 00 00 01 44 00 00
>    > rsp
>    > 80 01 00 00 00 0a 00 00 00 00
>    > Traceback (most recent call last):
>    >   File "tpm2-simulator-vtpm", line 85, in <module>
>    >     main()
>    >   File "tpm2-simulator-vtpm", line 80, in main
>    >     resp = client.send_cmd(stream)
>    >   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 454, in send_cmd
>    >     rsp = self.simulator.send_cmd(cmd)
>    >   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 436, in send_cmd
>    >     raise SimulatorError("Empty response")
>    > tpm2.SimulatorError: Empty response
>    >
>    > However, the process does not exit before the read call expires:
>    >
>    > $ python tpm2-list-handles
>    > Traceback (most recent call last):
>    >   File "tpm2-list-handles", line 61, in <module>
>    >     main()
>    >   File "tpm2-list-handles", line 51, in main
>    >     handles += client.get_cap(tpm2.TPM2_CAP_HANDLES,
>    tpm2.HR_LOADED_SESSION)
>    >   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 782, in get_cap
>    >     next_handles, more_data = self.__get_cap_cnt(cap, pt, 1)
>    >   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 766, in __get_cap_cnt
>    >     rsp = self.send_cmd(cmd)[10:]
>    >   File "/home/tpmdd/tpm2-scripts/tpm2.py", line 458, in send_cmd
>    >     rsp = f.read()
>    > IOError: [Errno 62] Timer expired
>    >
>    > The server side stays stuck unti this happens.
> 
>    This fix should solve the problem:
> 
>    diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c
>    b/drivers/char/tpm/tpm_vtpm_proxy.c
>    index d73944e..01e5070 100644
>    --- a/drivers/char/tpm/tpm_vtpm_proxy.c
>    +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
>    @@ -456,10 +456,10 @@ err_delete_proxy_dev:
>      */
>     static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
>     {
>    -       tpm_chip_unregister(proxy_dev->chip);
>    -
>            vtpm_proxy_fops_undo_open(proxy_dev);
> 
>    +      tpm_chip_unregister(proxy_dev->chip);
>    +
>            vtpm_proxy_delete_proxy_dev(proxy_dev);
>     }
> 
>    Can you let me know whether this gets it working for you? I'd prepare a
>    v9.

So is the deadlock such that:

* tpm_chip_unregister() tries to write lock ops_sem.
* tpm_transmit() holds read lock to ops_sem.

This takes two minutes if no timeouts are calculated.

And is the effect of moving vtpm_proxy_fops_undo_open() upwards such
that vtpm_proxy_tpm_req_canceled() starts returning true, which in
effect breaks the loop in tpm_transmit()?

Yeah, the fix as a code change is very simple but I had to use perf
probe to verify this so maybe a comment there would be in place to
tell why tpm_chip_unregister() must be called last (write lock).

>       Stefan

/Jarkko

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Stefan Berger March 13, 2016, 10:20 p.m. UTC | #3
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote on 03/13/2016 
04:06:52 PM:


> 
> On Sat, Mar 12, 2016 at 06:27:13PM -0500, Stefan Berger wrote:

> >    This fix should solve the problem:
> > 
> >    diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c
> >    b/drivers/char/tpm/tpm_vtpm_proxy.c
> >    index d73944e..01e5070 100644
> >    --- a/drivers/char/tpm/tpm_vtpm_proxy.c
> >    +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
> >    @@ -456,10 +456,10 @@ err_delete_proxy_dev:
> >      */
> >     static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
> >     {
> >    -       tpm_chip_unregister(proxy_dev->chip);
> >    -
> >            vtpm_proxy_fops_undo_open(proxy_dev);
> > 
> >    +      tpm_chip_unregister(proxy_dev->chip);
> >    +
> >            vtpm_proxy_delete_proxy_dev(proxy_dev);
> >     }
> > 
> >    Can you let me know whether this gets it working for you? I'd 
prepare a
> >    v9.
> 
> So is the deadlock such that:
> 
> * tpm_chip_unregister() tries to write lock ops_sem.
> * tpm_transmit() holds read lock to ops_sem.
> 
> This takes two minutes if no timeouts are calculated.
> 
> And is the effect of moving vtpm_proxy_fops_undo_open() upwards such
> that vtpm_proxy_tpm_req_canceled() starts returning true, which in
> effect breaks the loop in tpm_transmit()?
> 
> Yeah, the fix as a code change is very simple but I had to use perf
> probe to verify this so maybe a comment there would be in place to
> tell why tpm_chip_unregister() must be called last (write lock).

I'll put a comment. The reason is that the client (user of /dev/tpmX) is 
possibly holding the 'ops' lock while we the proxy driver needs it when 
calling tom_chip_unregister.
Thanks for trying it.

   Stefan
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Patch
diff mbox

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 3b84a8b..0eac596 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -122,5 +122,15 @@  config TCG_CRB
 	  from within Linux.  To compile this driver as a module, choose
 	  M here; the module will be called tpm_crb.
 
+config TCG_VTPM_PROXY
+	tristate "VTPM Proxy Interface"
+	depends on TCG_TPM
+	---help---
+	  This driver proxies for an emulated TPM (vTPM) running in userspace.
+	  A device /dev/vtpmx is provided that creates a device pair
+	  /dev/vtpmX and a server-side file descriptor on which the vTPM
+	  can receive commands.
+
+
 source "drivers/char/tpm/st33zp24/Kconfig"
 endif # TCG_TPM
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 56e8f1f..98de5e6 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -23,3 +23,4 @@  obj-$(CONFIG_TCG_IBMVTPM) += tpm_ibmvtpm.o
 obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/
 obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
 obj-$(CONFIG_TCG_CRB) += tpm_crb.o
+obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
new file mode 100644
index 0000000..d73944e
--- /dev/null
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -0,0 +1,567 @@ 
+/*
+ * Copyright (C) 2015, 2016 IBM Corporation
+ *
+ * Author: Stefan Berger <stefanb@us.ibm.com>
+ *
+ * Maintained by: <tpmdd-devel@lists.sourceforge.net>
+ *
+ * Device driver for vTPM (vTPM proxy driver)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/wait.h>
+#include <linux/miscdevice.h>
+#include <linux/vtpm_proxy.h>
+#include <linux/file.h>
+#include <linux/anon_inodes.h>
+#include <linux/poll.h>
+#include <linux/compat.h>
+
+#include "tpm.h"
+
+#define VTPM_PROXY_REQ_COMPLETE_FLAG  BIT(0)
+
+struct proxy_dev {
+	struct tpm_chip *chip;
+
+	u32 flags;                   /* public API flags */
+
+	wait_queue_head_t wq;
+
+	struct mutex buf_lock;       /* protect buffer and flags */
+
+	long state;                  /* internal state */
+#define STATE_OPENED_FLAG        BIT(0)
+#define STATE_WAIT_RESPONSE_FLAG BIT(1)  /* waiting for emulator response */
+
+	size_t req_len;              /* length of queued TPM request */
+	size_t resp_len;             /* length of queued TPM response */
+	u8 buffer[TPM_BUFSIZE];      /* request/response buffer */
+};
+
+
+static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev);
+
+/*
+ * Functions related to 'server side'
+ */
+
+/**
+ * vtpm_proxy_fops_read - Read TPM commands on 'server side'
+ *
+ * Return value:
+ *	Number of bytes read or negative error code
+ */
+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;
+
+	sig = wait_event_interruptible(proxy_dev->wq, proxy_dev->req_len != 0);
+	if (sig)
+		return -EINTR;
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	len = proxy_dev->req_len;
+
+	if (count < len) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
+			 count, len);
+		return -EIO;
+	}
+
+	rc = copy_to_user(buf, proxy_dev->buffer, len);
+	memset(proxy_dev->buffer, 0, len);
+	proxy_dev->req_len = 0;
+
+	if (!rc)
+		proxy_dev->state |= STATE_WAIT_RESPONSE_FLAG;
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	if (rc)
+		return -EFAULT;
+
+	return len;
+}
+
+/**
+ * vtpm_proxy_fops_write - Write TPM responses on 'server side'
+ *
+ * Return value:
+ *	Number of bytes read or negative error value
+ */
+static ssize_t vtpm_proxy_fops_write(struct file *filp, const char __user *buf,
+				     size_t count, loff_t *off)
+{
+	struct proxy_dev *proxy_dev = filp->private_data;
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	if (count > sizeof(proxy_dev->buffer) ||
+	    !(proxy_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EIO;
+	}
+
+	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
+
+	proxy_dev->req_len = 0;
+
+	if (copy_from_user(proxy_dev->buffer, buf, count)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EFAULT;
+	}
+
+	proxy_dev->resp_len = count;
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	wake_up_interruptible(&proxy_dev->wq);
+
+	return count;
+}
+
+/*
+ * vtpm_proxy_fops_poll: Poll status on 'server side'
+ *
+ * Return value:
+ *      Poll flags
+ */
+static unsigned int vtpm_proxy_fops_poll(struct file *filp, poll_table *wait)
+{
+	struct proxy_dev *proxy_dev = filp->private_data;
+	unsigned ret;
+
+	poll_wait(filp, &proxy_dev->wq, wait);
+
+	ret = POLLOUT;
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	if (proxy_dev->req_len)
+		ret |= POLLIN | POLLRDNORM;
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	return ret;
+}
+
+/*
+ * vtpm_proxy_fops_open - Open vTPM device on 'server side'
+ *
+ * Called when setting up the anonymous file descriptor
+ */
+static void vtpm_proxy_fops_open(struct file *filp)
+{
+	struct proxy_dev *proxy_dev = filp->private_data;
+
+	proxy_dev->state |= STATE_OPENED_FLAG;
+}
+
+/**
+ * vtpm_proxy_fops_undo_open - counter-part to vtpm_fops_open
+ *
+ * Call to undo vtpm_proxy_fops_open
+ */
+static void vtpm_proxy_fops_undo_open(struct proxy_dev *proxy_dev)
+{
+	mutex_lock(&proxy_dev->buf_lock);
+
+	proxy_dev->state &= ~STATE_OPENED_FLAG;
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	/* no more TPM responses -- wake up anyone waiting for them */
+	wake_up_interruptible(&proxy_dev->wq);
+}
+
+/*
+ * vtpm_proxy_fops_release: Close 'server side'
+ *
+ * Return value:
+ *      Always returns 0.
+ */
+static int vtpm_proxy_fops_release(struct inode *inode, struct file *filp)
+{
+	struct proxy_dev *proxy_dev = filp->private_data;
+
+	filp->private_data = NULL;
+
+	vtpm_proxy_delete_device(proxy_dev);
+
+	return 0;
+}
+
+static const struct file_operations vtpm_proxy_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.read = vtpm_proxy_fops_read,
+	.write = vtpm_proxy_fops_write,
+	.poll = vtpm_proxy_fops_poll,
+	.release = vtpm_proxy_fops_release,
+};
+
+/*
+ * Functions invoked by the core TPM driver to send TPM commands to
+ * 'server side' and receive responses from there.
+ */
+
+/*
+ * Called when core TPM driver reads TPM responses from 'server side'
+ *
+ * Return value:
+ *      Number of TPM response bytes read, negative error value otherwise
+ */
+static int vtpm_proxy_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	struct proxy_dev *proxy_dev = chip->vendor.priv;
+	size_t len;
+
+	if (!proxy_dev)
+		return -EIO;
+
+	/* process gone ? */
+	mutex_lock(&proxy_dev->buf_lock);
+
+	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EPIPE;
+	}
+
+	len = proxy_dev->resp_len;
+	if (count < len) {
+		dev_err(&chip->dev,
+			"Invalid size in recv: count=%zd, resp_len=%zd\n",
+			count, len);
+		len = -EIO;
+		goto out;
+	}
+
+	memcpy(buf, proxy_dev->buffer, len);
+	proxy_dev->resp_len = 0;
+
+out:
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	return len;
+}
+
+/*
+ * Called when core TPM driver forwards TPM requests to 'server side'.
+ *
+ * Return value:
+ *      0 in case of success, negative error value otherwise.
+ */
+static int vtpm_proxy_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	struct proxy_dev *proxy_dev = chip->vendor.priv;
+	int rc = 0;
+
+	if (!proxy_dev)
+		return -EIO;
+
+	if (count > sizeof(proxy_dev->buffer)) {
+		dev_err(&chip->dev,
+			"Invalid size in send: count=%zd, buffer size=%zd\n",
+			count, sizeof(proxy_dev->buffer));
+		return -EIO;
+	}
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EPIPE;
+	}
+
+	proxy_dev->resp_len = 0;
+
+	proxy_dev->req_len = count;
+	memcpy(proxy_dev->buffer, buf, count);
+
+	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	wake_up_interruptible(&proxy_dev->wq);
+
+	return rc;
+}
+
+static void vtpm_proxy_tpm_op_cancel(struct tpm_chip *chip)
+{
+	/* not supported */
+}
+
+static u8 vtpm_proxy_tpm_op_status(struct tpm_chip *chip)
+{
+	struct proxy_dev *proxy_dev = chip->vendor.priv;
+
+	if (proxy_dev->resp_len)
+		return VTPM_PROXY_REQ_COMPLETE_FLAG;
+
+	return 0;
+}
+
+static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
+{
+	struct proxy_dev *proxy_dev = chip->vendor.priv;
+	bool ret;
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	ret = !(proxy_dev->state & STATE_OPENED_FLAG);
+
+	mutex_unlock(&proxy_dev->buf_lock);
+
+	return ret;
+}
+
+static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
+	.recv = vtpm_proxy_tpm_op_recv,
+	.send = vtpm_proxy_tpm_op_send,
+	.cancel = vtpm_proxy_tpm_op_cancel,
+	.status = vtpm_proxy_tpm_op_status,
+	.req_complete_mask = VTPM_PROXY_REQ_COMPLETE_FLAG,
+	.req_complete_val = VTPM_PROXY_REQ_COMPLETE_FLAG,
+	.req_canceled = vtpm_proxy_tpm_req_canceled,
+};
+
+/*
+ * Code related to creation and deletion of device pairs
+ */
+static struct proxy_dev *vtpm_proxy_create_proxy_dev(void)
+{
+	struct proxy_dev *proxy_dev;
+	struct tpm_chip *chip;
+	int err;
+
+	proxy_dev = kzalloc(sizeof(*proxy_dev), GFP_KERNEL);
+	if (proxy_dev == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	init_waitqueue_head(&proxy_dev->wq);
+	mutex_init(&proxy_dev->buf_lock);
+
+	chip = tpm_chip_alloc(NULL, &vtpm_proxy_tpm_ops);
+	if (IS_ERR(chip)) {
+		err = PTR_ERR(chip);
+		goto err_proxy_dev_free;
+	}
+	chip->vendor.priv = proxy_dev;
+
+	proxy_dev->chip = chip;
+
+	return proxy_dev;
+
+err_proxy_dev_free:
+	kfree(proxy_dev);
+
+	return ERR_PTR(err);
+}
+
+/*
+ * Undo what has been done in vtpm_create_proxy_dev
+ */
+static inline void vtpm_proxy_delete_proxy_dev(struct proxy_dev *proxy_dev)
+{
+	put_device(&proxy_dev->chip->dev); /* frees chip */
+	kfree(proxy_dev);
+}
+
+/*
+ * Create a /dev/tpm%d and 'server side' file descriptor pair
+ *
+ * Return value:
+ *      Returns file pointer on success, an error value otherwise
+ */
+static struct file *vtpm_proxy_create_device(
+				 struct vtpm_proxy_new_dev *vtpm_new_dev)
+{
+	struct proxy_dev *proxy_dev;
+	int rc, fd;
+	struct file *file;
+
+	if (vtpm_new_dev->flags & ~VTPM_PROXY_FLAGS_ALL)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	proxy_dev = vtpm_proxy_create_proxy_dev();
+	if (IS_ERR(proxy_dev))
+		return ERR_CAST(proxy_dev);
+
+	proxy_dev->flags = vtpm_new_dev->flags;
+
+	/* setup an anonymous file for the server-side */
+	fd = get_unused_fd_flags(O_RDWR);
+	if (fd < 0) {
+		rc = fd;
+		goto err_delete_proxy_dev;
+	}
+
+	file = anon_inode_getfile("[vtpms]", &vtpm_proxy_fops, proxy_dev,
+				  O_RDWR);
+	if (IS_ERR(file)) {
+		rc = PTR_ERR(file);
+		goto err_put_unused_fd;
+	}
+
+	/* from now on we can unwind with put_unused_fd() + fput() */
+	/* simulate an open() on the server side */
+	vtpm_proxy_fops_open(file);
+
+	if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
+		proxy_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;
+
+	rc = tpm_chip_register(proxy_dev->chip);
+	if (rc)
+		goto err_vtpm_fput;
+
+	vtpm_new_dev->fd = fd;
+	vtpm_new_dev->major = MAJOR(proxy_dev->chip->dev.devt);
+	vtpm_new_dev->minor = MINOR(proxy_dev->chip->dev.devt);
+	vtpm_new_dev->tpm_num = proxy_dev->chip->dev_num;
+
+	return file;
+
+err_vtpm_fput:
+	put_unused_fd(fd);
+	fput(file);
+
+	return ERR_PTR(rc);
+
+err_put_unused_fd:
+	put_unused_fd(fd);
+
+err_delete_proxy_dev:
+	vtpm_proxy_delete_proxy_dev(proxy_dev);
+
+	return ERR_PTR(rc);
+}
+
+/*
+ * Counter part to vtpm_create_device.
+ */
+static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
+{
+	tpm_chip_unregister(proxy_dev->chip);
+
+	vtpm_proxy_fops_undo_open(proxy_dev);
+
+	vtpm_proxy_delete_proxy_dev(proxy_dev);
+}
+
+/*
+ * Code related to the control device /dev/vtpmx
+ */
+
+/*
+ * vtpmx_fops_ioctl: ioctl on /dev/vtpmx
+ *
+ * Return value:
+ *      Returns 0 on success, a negative error code otherwise.
+ */
+static long vtpmx_fops_ioctl(struct file *f, unsigned int ioctl,
+				   unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	struct vtpm_proxy_new_dev *vtpm_new_dev_p;
+	struct vtpm_proxy_new_dev vtpm_new_dev;
+	struct file *file;
+
+	switch (ioctl) {
+	case VTPM_PROXY_IOC_NEW_DEV:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		vtpm_new_dev_p = argp;
+		if (copy_from_user(&vtpm_new_dev, vtpm_new_dev_p,
+				   sizeof(vtpm_new_dev)))
+			return -EFAULT;
+		file = vtpm_proxy_create_device(&vtpm_new_dev);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
+		if (copy_to_user(vtpm_new_dev_p, &vtpm_new_dev,
+				 sizeof(vtpm_new_dev))) {
+			put_unused_fd(vtpm_new_dev.fd);
+			fput(file);
+			return -EFAULT;
+		}
+
+		fd_install(vtpm_new_dev.fd, file);
+		return 0;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+#ifdef CONFIG_COMPAT
+static long vtpmx_fops_compat_ioctl(struct file *f, unsigned int ioctl,
+					  unsigned long arg)
+{
+	return vtpmx_fops_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static const struct file_operations vtpmx_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = vtpmx_fops_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = vtpmx_fops_compat_ioctl,
+#endif
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice vtpmx_miscdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "vtpmx",
+	.fops = &vtpmx_fops,
+};
+
+static int vtpmx_init(void)
+{
+	return misc_register(&vtpmx_miscdev);
+}
+
+static void vtpmx_cleanup(void)
+{
+	misc_deregister(&vtpmx_miscdev);
+}
+
+static int __init vtpm_module_init(void)
+{
+	int rc;
+
+	rc = vtpmx_init();
+	if (rc) {
+		pr_err("couldn't create vtpmx device\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+static void __exit vtpm_module_exit(void)
+{
+	vtpmx_cleanup();
+}
+
+module_init(vtpm_module_init);
+module_exit(vtpm_module_exit);
+
+MODULE_AUTHOR("Stefan Berger (stefanb@us.ibm.com)");
+MODULE_DESCRIPTION("vTPM Driver");
+MODULE_VERSION("0.1");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index ebd10e6..ac767ce 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -449,6 +449,7 @@  header-y += virtio_scsi.h
 header-y += virtio_types.h
 header-y += vm_sockets.h
 header-y += vt.h
+header-y += vtpm_proxy.h
 header-y += wait.h
 header-y += wanrouter.h
 header-y += watchdog.h
diff --git a/include/uapi/linux/vtpm_proxy.h b/include/uapi/linux/vtpm_proxy.h
new file mode 100644
index 0000000..dc73f00
--- /dev/null
+++ b/include/uapi/linux/vtpm_proxy.h
@@ -0,0 +1,42 @@ 
+/*
+ * Definitions for the VTPM proxy driver
+ * Copyright (c) 2015, 2016, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef _UAPI_LINUX_VTPM_PROXY_H
+#define _UAPI_LINUX_VTPM_PROXY_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/* ioctls */
+
+struct vtpm_proxy_new_dev {
+	__u32 flags;         /* input */
+	__u32 tpm_num;       /* output */
+	__u32 fd;            /* output */
+	__u32 major;         /* output */
+	__u32 minor;         /* output */
+};
+
+/* above flags */
+#define VTPM_PROXY_FLAG_TPM2  1  /* emulator is TPM 2 */
+
+/* all supported flags */
+#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2)
+
+#define VTPM_PROXY_MAGIC 0xa1
+
+#define VTPM_PROXY_IOC_NEW_DEV   _IOW(VTPM_PROXY_MAGIC, 0x00, \
+				      struct vtpm_proxy_new_dev)
+
+#endif /* _UAPI_LINUX_VTPM_PROXY_H */