[tpmdd-devel,v6,08/11] tpm: Driver for supporting multiple emulated TPMs

This patch implements a 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.c | 566 ++++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild   |   1 +
 include/uapi/linux/vtpm.h   |  41 ++++
 5 files changed, 619 insertions(+)
 create mode 100644 drivers/char/tpm/tpm_vtpm.c
 create mode 100644 include/uapi/linux/vtpm.h

On Wed, Mar 9, 2016 at 9:39 AM, Stefan Berger
<stefanb@linux.vnet.ibm.com> wrote:
> This patch implements a 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.

Nifty!

Is anyone considering writing a modification or replacement of
trousers that creates claims the real tpm and exposes a vtpm that
handles multiplexing internally?  Does the vtpm driver intelligently
support multiple simultaneous clients?

--Andy

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Andy Lutomirski <luto@amacapital.net> wrote on 03/09/2016 01:01:05 PM:


> 
> On Wed, Mar 9, 2016 at 9:39 AM, Stefan Berger
> <stefanb@linux.vnet.ibm.com> wrote:
> > This patch implements a 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.
> 
> Nifty!
> 
> Is anyone considering writing a modification or replacement of
> trousers that creates claims the real tpm and exposes a vtpm that
> handles multiplexing internally?  Does the vtpm driver intelligently
> support multiple simultaneous clients?

The vtpm driver allows to use an independent trousers instance in each 
container.

Using the VTPM_NEW_DEV ioctl the container mgmt. stack can create a 
/dev/tpmX (X=0,1,2,...) device and a file descriptor. The file descriptor 
is passed to a vTPM instance, the /dev/tpmX is moved into the container, 
meaning a device with the same major/minor numbers is created in the 
container. This then allows each container to talk to an independent vTPM. 
The vTPM can either be 1.2 or 2.

   Stefan
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On Wed, Mar 09, 2016 at 12:39:27PM -0500, Stefan Berger wrote:
> This patch implements a 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.c | 566 ++++++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/Kbuild   |   1 +
>  include/uapi/linux/vtpm.h   |  41 ++++
>  5 files changed, 619 insertions(+)
>  create mode 100644 drivers/char/tpm/tpm_vtpm.c
>  create mode 100644 include/uapi/linux/vtpm.h
> 
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 3b84a8b..4c4e843 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
> +	tristate "VTPM Interface"
> +	depends on TCG_TPM
> +	---help---
> +	  This driver supports 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..1a409c57 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) += tpm_vtpm.o
> diff --git a/drivers/char/tpm/tpm_vtpm.c b/drivers/char/tpm/tpm_vtpm.c
> new file mode 100644
> index 0000000..0da311b
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_vtpm.c
> @@ -0,0 +1,566 @@
> +/*
> + * Copyright (C) 2015, 2016 IBM Corporation
> + *
> + * Author: Stefan Berger <stefanb@us.ibm.com>
> + *
> + * Maintained by: <tpmdd-devel@lists.sourceforge.net>
> + *
> + * Device driver for vTPM.
> + *
> + * 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.h>
> +#include <linux/file.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/poll.h>
> +#include <linux/compat.h>
> +
> +#include "tpm.h"
> +
> +#define VTPM_REQ_COMPLETE_FLAG  BIT(0)
> +
> +struct vtpm_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_delete_device(struct vtpm_dev *vtpm_dev);
> +
> +/*
> + * Functions related to 'server side'
> + */
> +
> +/**
> + * vtpm_fops_read - Read TPM commands on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error code
> + */
> +static ssize_t vtpm_fops_read(struct file *filp, char __user *buf,
> +			      size_t count, loff_t *off)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +	size_t len;
> +	int sig, rc;
> +
> +	sig = wait_event_interruptible(vtpm_dev->wq, vtpm_dev->req_len != 0);
> +	if (sig)
> +		return -EINTR;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	len = vtpm_dev->req_len;
> +
> +	if (count < len) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
> +			 count, len);
> +		return -EIO;
> +	}
> +
> +	rc = copy_to_user(buf, vtpm_dev->buffer, len);
> +	memset(vtpm_dev->buffer, 0, len);
> +	vtpm_dev->req_len = 0;
> +
> +	if (!rc)
> +		vtpm_dev->state |= STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	if (rc)
> +		return -EFAULT;
> +
> +	return len;
> +}
> +
> +/**
> + * vtpm_fops_write - Write TPM responses on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error value
> + */
> +static ssize_t vtpm_fops_write(struct file *filp, const char __user *buf,
> +			       size_t count, loff_t *off)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (count > sizeof(vtpm_dev->buffer) ||
> +	    !(vtpm_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EIO;
> +	}
> +
> +	vtpm_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	vtpm_dev->req_len = 0;
> +
> +	if (copy_from_user(vtpm_dev->buffer, buf, count)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EFAULT;
> +	}
> +
> +	vtpm_dev->resp_len = count;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	wake_up_interruptible(&vtpm_dev->wq);
> +
> +	return count;
> +}
> +
> +/*
> + * vtpm_fops_poll: Poll status on 'server side'
> + *
> + * Return value:
> + *      Poll flags
> + */
> +static unsigned int vtpm_fops_poll(struct file *filp, poll_table *wait)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +	unsigned ret;
> +
> +	poll_wait(filp, &vtpm_dev->wq, wait);
> +
> +	ret = POLLOUT;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (vtpm_dev->req_len)
> +		ret |= POLLIN | POLLRDNORM;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * vtpm_fops_open - Open vTPM device on 'server side'
> + *
> + * Called when setting up the anonymous file descriptor
> + */
> +static void vtpm_fops_open(struct file *filp)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	vtpm_dev->state |= STATE_OPENED_FLAG;
> +}
> +
> +/**
> + * vtpm_fops_undo_open - counter-part to vtpm_fops_open
> + *
> + * Call to undo vtpm_fops_open
> + */
> +static void vtpm_fops_undo_open(struct vtpm_dev *vtpm_dev)
> +{
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	vtpm_dev->state &= ~STATE_OPENED_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	/* no more TPM responses -- wake up anyone waiting for them */
> +	wake_up_interruptible(&vtpm_dev->wq);
> +}
> +
> +/*
> + * vtpm_fops_release: Close 'server side'
> + *
> + * Return value:
> + *      Always returns 0.
> + */
> +static int vtpm_fops_release(struct inode *inode, struct file *filp)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	filp->private_data = NULL;
> +
> +	vtpm_delete_device(vtpm_dev);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations vtpm_fops = {
> +	.owner = THIS_MODULE,
> +	.llseek = no_llseek,
> +	.read = vtpm_fops_read,
> +	.write = vtpm_fops_write,
> +	.poll = vtpm_fops_poll,
> +	.release = vtpm_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_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	size_t len;
> +
> +	if (!vtpm_dev)
> +		return -EIO;
> +
> +	/* process gone ? */
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (!(vtpm_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	len = vtpm_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, vtpm_dev->buffer, len);
> +	vtpm_dev->resp_len = 0;
> +
> +out:
> +	mutex_unlock(&vtpm_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_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	int rc = 0;
> +
> +	if (!vtpm_dev)
> +		return -EIO;
> +
> +	if (count > sizeof(vtpm_dev->buffer)) {
> +		dev_err(&chip->dev,
> +			"Invalid size in send: count=%zd, buffer size=%zd\n",
> +			count, sizeof(vtpm_dev->buffer));
> +		return -EIO;
> +	}
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (!(vtpm_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	vtpm_dev->resp_len = 0;
> +
> +	vtpm_dev->req_len = count;
> +	memcpy(vtpm_dev->buffer, buf, count);
> +
> +	vtpm_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	wake_up_interruptible(&vtpm_dev->wq);
> +
> +	return rc;
> +}
> +
> +static void vtpm_tpm_op_cancel(struct tpm_chip *chip)
> +{
> +	/* not supported */
> +}
> +
> +static u8 vtpm_tpm_op_status(struct tpm_chip *chip)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +
> +	if (vtpm_dev->resp_len)
> +		return VTPM_REQ_COMPLETE_FLAG;
> +
> +	return 0;
> +}
> +
> +static bool vtpm_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	bool ret;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	ret = !(vtpm_dev->state & STATE_OPENED_FLAG);
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +static const struct tpm_class_ops vtpm_tpm_ops = {
> +	.recv = vtpm_tpm_op_recv,
> +	.send = vtpm_tpm_op_send,
> +	.cancel = vtpm_tpm_op_cancel,
> +	.status = vtpm_tpm_op_status,
> +	.req_complete_mask = VTPM_REQ_COMPLETE_FLAG,
> +	.req_complete_val = VTPM_REQ_COMPLETE_FLAG,
> +	.req_canceled = vtpm_tpm_req_canceled,
> +};
> +
> +/*
> + * Code related to creation and deletion of device pairs
> + */
> +static struct vtpm_dev *vtpm_create_vtpm_dev(void)
> +{
> +	struct vtpm_dev *vtpm_dev;
> +	struct tpm_chip *chip;
> +	int err;
> +
> +	vtpm_dev = kzalloc(sizeof(*vtpm_dev), GFP_KERNEL);
> +	if (vtpm_dev == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	init_waitqueue_head(&vtpm_dev->wq);
> +	mutex_init(&vtpm_dev->buf_lock);
> +
> +	chip = tpm_chip_alloc(NULL, &vtpm_tpm_ops);
> +	if (IS_ERR(chip)) {
> +		err = PTR_ERR(chip);
> +		goto err_vtpm_dev_free;
> +	}
> +	chip->vendor.priv = vtpm_dev;
> +
> +	vtpm_dev->chip = chip;
> +
> +	return vtpm_dev;
> +
> +err_vtpm_dev_free:
> +	kfree(vtpm_dev);
> +
> +	return ERR_PTR(err);
> +}
> +
> +/*
> + * Undo what has been done in vtpm_create_vtpm_dev
> + */
> +static inline void vtpm_delete_vtpm_dev(struct vtpm_dev *vtpm_dev)
> +{
> +	put_device(&vtpm_dev->chip->dev); /* frees chip */
> +	kfree(vtpm_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_create_device(
> +				       struct vtpm_new_dev *vtpm_new_dev)
> +{
> +	struct vtpm_dev *vtpm_dev;
> +	int rc, fd;
> +	struct file *file;
> +
> +	if (vtpm_new_dev->flags & ~VTPM_FLAGS_ALL)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	vtpm_dev = vtpm_create_vtpm_dev();
> +	if (IS_ERR(vtpm_dev))
> +		return ERR_CAST(vtpm_dev);
> +
> +	vtpm_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_vtpm_dev;
> +	}
> +
> +	file = anon_inode_getfile("[vtpms]", &vtpm_fops, vtpm_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_fops_open(file);
> +
> +	if (vtpm_dev->flags & VTPM_FLAG_TPM2)
> +		vtpm_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;
> +
> +	rc = tpm_chip_register(vtpm_dev->chip);
> +	if (rc)
> +		goto err_vtpm_fput;
> +
> +	vtpm_new_dev->fd = fd;
> +	vtpm_new_dev->major = MAJOR(vtpm_dev->chip->dev.devt);
> +	vtpm_new_dev->minor = MINOR(vtpm_dev->chip->dev.devt);
> +	vtpm_new_dev->dev_num = vtpm_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_vtpm_dev:
> +	vtpm_delete_vtpm_dev(vtpm_dev);
> +
> +	return ERR_PTR(rc);
> +}
> +
> +/*
> + * Counter part to vtpm_create_device.
> + */
> +static void vtpm_delete_device(struct vtpm_dev *vtpm_dev)
> +{
> +	tpm_chip_unregister(vtpm_dev->chip);
> +
> +	vtpm_fops_undo_open(vtpm_dev);
> +
> +	vtpm_delete_vtpm_dev(vtpm_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_new_dev *vtpm_new_dev_p;
> +	struct vtpm_new_dev vtpm_new_dev;
> +	struct file *file;
> +
> +	switch (ioctl) {
> +	case VTPM_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_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..3a602c9 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.h
>  header-y += wait.h
>  header-y += wanrouter.h
>  header-y += watchdog.h
> diff --git a/include/uapi/linux/vtpm.h b/include/uapi/linux/vtpm.h
> new file mode 100644
> index 0000000..4adc486
> --- /dev/null
> +++ b/include/uapi/linux/vtpm.h
> @@ -0,0 +1,41 @@
> +/*
> + * Definitions for the VTPM interface
> + * 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_H
> +#define _UAPI_LINUX_VTPM_H
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +/* ioctls */
> +
> +struct vtpm_new_dev {
> +	__u32 flags;         /* input */
> +	__u32 dev_num;       /* output */

I think 'tpm_num' that you mentioned in our earlier discussions  would
be a more accurate name. Yes, device number is one of the contexts where
this number is used to index a TPM chip but the same index is also used
in the context when kernel uses the TPM.

/Jarkko

> +	__u32 fd;            /* output */
> +	__u32 major;         /* output */
> +	__u32 minor;         /* output */
> +};
> +
> +/* above flags */
> +#define VTPM_FLAG_TPM2           1  /* emulator is TPM 2 */
> +
> +/* all supported flags */
> +#define VTPM_FLAGS_ALL  (VTPM_FLAG_TPM2)
> +
> +#define VTPM_TPM 0xa0
> +
> +#define VTPM_NEW_DEV         _IOW(VTPM_TPM, 0x00, struct vtpm_new_dev)
> +
> +#endif /* _UAPI_LINUX_VTPM_H */
> -- 
> 2.4.3
> 

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On Wed, Mar 09, 2016 at 12:39:27PM -0500, Stefan Berger wrote:
> This patch implements a 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.

I wrote my first test program 'tpm2-simulator-vtpm' that at the moment
opens /dev/vtpmx and creates a device. As next step I'm going to
extend this script to connect MS TPM 2.0 simulator based on the work
by Peter Huewe.

It is available here:

git://git.infradead.org/users/jjs/tpm2-scripts.git

The first obvious thing that I observed is that the device is closed
when /dev/vtpmx is closed.

Some might want to use this in a way that the created virtual device
is not closed when /dev/vtpmx is closed.

However, since we have the 'flags' parameter in struct vtpm_new_dev
this is not an issue. We could later on add a new flag for this
behavior and add a new ioctl for destroying a vtpm device. Do you see
that anything would prevent adding this functionality later on if we
ever need it?

/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.c | 566 ++++++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/Kbuild   |   1 +
>  include/uapi/linux/vtpm.h   |  41 ++++
>  5 files changed, 619 insertions(+)
>  create mode 100644 drivers/char/tpm/tpm_vtpm.c
>  create mode 100644 include/uapi/linux/vtpm.h
> 
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 3b84a8b..4c4e843 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
> +	tristate "VTPM Interface"
> +	depends on TCG_TPM
> +	---help---
> +	  This driver supports 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..1a409c57 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) += tpm_vtpm.o
> diff --git a/drivers/char/tpm/tpm_vtpm.c b/drivers/char/tpm/tpm_vtpm.c
> new file mode 100644
> index 0000000..0da311b
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_vtpm.c
> @@ -0,0 +1,566 @@
> +/*
> + * Copyright (C) 2015, 2016 IBM Corporation
> + *
> + * Author: Stefan Berger <stefanb@us.ibm.com>
> + *
> + * Maintained by: <tpmdd-devel@lists.sourceforge.net>
> + *
> + * Device driver for vTPM.
> + *
> + * 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.h>
> +#include <linux/file.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/poll.h>
> +#include <linux/compat.h>
> +
> +#include "tpm.h"
> +
> +#define VTPM_REQ_COMPLETE_FLAG  BIT(0)
> +
> +struct vtpm_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_delete_device(struct vtpm_dev *vtpm_dev);
> +
> +/*
> + * Functions related to 'server side'
> + */
> +
> +/**
> + * vtpm_fops_read - Read TPM commands on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error code
> + */
> +static ssize_t vtpm_fops_read(struct file *filp, char __user *buf,
> +			      size_t count, loff_t *off)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +	size_t len;
> +	int sig, rc;
> +
> +	sig = wait_event_interruptible(vtpm_dev->wq, vtpm_dev->req_len != 0);
> +	if (sig)
> +		return -EINTR;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	len = vtpm_dev->req_len;
> +
> +	if (count < len) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
> +			 count, len);
> +		return -EIO;
> +	}
> +
> +	rc = copy_to_user(buf, vtpm_dev->buffer, len);
> +	memset(vtpm_dev->buffer, 0, len);
> +	vtpm_dev->req_len = 0;
> +
> +	if (!rc)
> +		vtpm_dev->state |= STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	if (rc)
> +		return -EFAULT;
> +
> +	return len;
> +}
> +
> +/**
> + * vtpm_fops_write - Write TPM responses on 'server side'
> + *
> + * Return value:
> + *	Number of bytes read or negative error value
> + */
> +static ssize_t vtpm_fops_write(struct file *filp, const char __user *buf,
> +			       size_t count, loff_t *off)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (count > sizeof(vtpm_dev->buffer) ||
> +	    !(vtpm_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EIO;
> +	}
> +
> +	vtpm_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	vtpm_dev->req_len = 0;
> +
> +	if (copy_from_user(vtpm_dev->buffer, buf, count)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EFAULT;
> +	}
> +
> +	vtpm_dev->resp_len = count;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	wake_up_interruptible(&vtpm_dev->wq);
> +
> +	return count;
> +}
> +
> +/*
> + * vtpm_fops_poll: Poll status on 'server side'
> + *
> + * Return value:
> + *      Poll flags
> + */
> +static unsigned int vtpm_fops_poll(struct file *filp, poll_table *wait)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +	unsigned ret;
> +
> +	poll_wait(filp, &vtpm_dev->wq, wait);
> +
> +	ret = POLLOUT;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (vtpm_dev->req_len)
> +		ret |= POLLIN | POLLRDNORM;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * vtpm_fops_open - Open vTPM device on 'server side'
> + *
> + * Called when setting up the anonymous file descriptor
> + */
> +static void vtpm_fops_open(struct file *filp)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	vtpm_dev->state |= STATE_OPENED_FLAG;
> +}
> +
> +/**
> + * vtpm_fops_undo_open - counter-part to vtpm_fops_open
> + *
> + * Call to undo vtpm_fops_open
> + */
> +static void vtpm_fops_undo_open(struct vtpm_dev *vtpm_dev)
> +{
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	vtpm_dev->state &= ~STATE_OPENED_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	/* no more TPM responses -- wake up anyone waiting for them */
> +	wake_up_interruptible(&vtpm_dev->wq);
> +}
> +
> +/*
> + * vtpm_fops_release: Close 'server side'
> + *
> + * Return value:
> + *      Always returns 0.
> + */
> +static int vtpm_fops_release(struct inode *inode, struct file *filp)
> +{
> +	struct vtpm_dev *vtpm_dev = filp->private_data;
> +
> +	filp->private_data = NULL;
> +
> +	vtpm_delete_device(vtpm_dev);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations vtpm_fops = {
> +	.owner = THIS_MODULE,
> +	.llseek = no_llseek,
> +	.read = vtpm_fops_read,
> +	.write = vtpm_fops_write,
> +	.poll = vtpm_fops_poll,
> +	.release = vtpm_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_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	size_t len;
> +
> +	if (!vtpm_dev)
> +		return -EIO;
> +
> +	/* process gone ? */
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (!(vtpm_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	len = vtpm_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, vtpm_dev->buffer, len);
> +	vtpm_dev->resp_len = 0;
> +
> +out:
> +	mutex_unlock(&vtpm_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_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	int rc = 0;
> +
> +	if (!vtpm_dev)
> +		return -EIO;
> +
> +	if (count > sizeof(vtpm_dev->buffer)) {
> +		dev_err(&chip->dev,
> +			"Invalid size in send: count=%zd, buffer size=%zd\n",
> +			count, sizeof(vtpm_dev->buffer));
> +		return -EIO;
> +	}
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	if (!(vtpm_dev->state & STATE_OPENED_FLAG)) {
> +		mutex_unlock(&vtpm_dev->buf_lock);
> +		return -EPIPE;
> +	}
> +
> +	vtpm_dev->resp_len = 0;
> +
> +	vtpm_dev->req_len = count;
> +	memcpy(vtpm_dev->buffer, buf, count);
> +
> +	vtpm_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	wake_up_interruptible(&vtpm_dev->wq);
> +
> +	return rc;
> +}
> +
> +static void vtpm_tpm_op_cancel(struct tpm_chip *chip)
> +{
> +	/* not supported */
> +}
> +
> +static u8 vtpm_tpm_op_status(struct tpm_chip *chip)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +
> +	if (vtpm_dev->resp_len)
> +		return VTPM_REQ_COMPLETE_FLAG;
> +
> +	return 0;
> +}
> +
> +static bool vtpm_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
> +{
> +	struct vtpm_dev *vtpm_dev = chip->vendor.priv;
> +	bool ret;
> +
> +	mutex_lock(&vtpm_dev->buf_lock);
> +
> +	ret = !(vtpm_dev->state & STATE_OPENED_FLAG);
> +
> +	mutex_unlock(&vtpm_dev->buf_lock);
> +
> +	return ret;
> +}
> +
> +static const struct tpm_class_ops vtpm_tpm_ops = {
> +	.recv = vtpm_tpm_op_recv,
> +	.send = vtpm_tpm_op_send,
> +	.cancel = vtpm_tpm_op_cancel,
> +	.status = vtpm_tpm_op_status,
> +	.req_complete_mask = VTPM_REQ_COMPLETE_FLAG,
> +	.req_complete_val = VTPM_REQ_COMPLETE_FLAG,
> +	.req_canceled = vtpm_tpm_req_canceled,
> +};
> +
> +/*
> + * Code related to creation and deletion of device pairs
> + */
> +static struct vtpm_dev *vtpm_create_vtpm_dev(void)
> +{
> +	struct vtpm_dev *vtpm_dev;
> +	struct tpm_chip *chip;
> +	int err;
> +
> +	vtpm_dev = kzalloc(sizeof(*vtpm_dev), GFP_KERNEL);
> +	if (vtpm_dev == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	init_waitqueue_head(&vtpm_dev->wq);
> +	mutex_init(&vtpm_dev->buf_lock);
> +
> +	chip = tpm_chip_alloc(NULL, &vtpm_tpm_ops);
> +	if (IS_ERR(chip)) {
> +		err = PTR_ERR(chip);
> +		goto err_vtpm_dev_free;
> +	}
> +	chip->vendor.priv = vtpm_dev;
> +
> +	vtpm_dev->chip = chip;
> +
> +	return vtpm_dev;
> +
> +err_vtpm_dev_free:
> +	kfree(vtpm_dev);
> +
> +	return ERR_PTR(err);
> +}
> +
> +/*
> + * Undo what has been done in vtpm_create_vtpm_dev
> + */
> +static inline void vtpm_delete_vtpm_dev(struct vtpm_dev *vtpm_dev)
> +{
> +	put_device(&vtpm_dev->chip->dev); /* frees chip */
> +	kfree(vtpm_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_create_device(
> +				       struct vtpm_new_dev *vtpm_new_dev)
> +{
> +	struct vtpm_dev *vtpm_dev;
> +	int rc, fd;
> +	struct file *file;
> +
> +	if (vtpm_new_dev->flags & ~VTPM_FLAGS_ALL)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	vtpm_dev = vtpm_create_vtpm_dev();
> +	if (IS_ERR(vtpm_dev))
> +		return ERR_CAST(vtpm_dev);
> +
> +	vtpm_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_vtpm_dev;
> +	}
> +
> +	file = anon_inode_getfile("[vtpms]", &vtpm_fops, vtpm_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_fops_open(file);
> +
> +	if (vtpm_dev->flags & VTPM_FLAG_TPM2)
> +		vtpm_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;
> +
> +	rc = tpm_chip_register(vtpm_dev->chip);
> +	if (rc)
> +		goto err_vtpm_fput;
> +
> +	vtpm_new_dev->fd = fd;
> +	vtpm_new_dev->major = MAJOR(vtpm_dev->chip->dev.devt);
> +	vtpm_new_dev->minor = MINOR(vtpm_dev->chip->dev.devt);
> +	vtpm_new_dev->dev_num = vtpm_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_vtpm_dev:
> +	vtpm_delete_vtpm_dev(vtpm_dev);
> +
> +	return ERR_PTR(rc);
> +}
> +
> +/*
> + * Counter part to vtpm_create_device.
> + */
> +static void vtpm_delete_device(struct vtpm_dev *vtpm_dev)
> +{
> +	tpm_chip_unregister(vtpm_dev->chip);
> +
> +	vtpm_fops_undo_open(vtpm_dev);
> +
> +	vtpm_delete_vtpm_dev(vtpm_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_new_dev *vtpm_new_dev_p;
> +	struct vtpm_new_dev vtpm_new_dev;
> +	struct file *file;
> +
> +	switch (ioctl) {
> +	case VTPM_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_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..3a602c9 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.h
>  header-y += wait.h
>  header-y += wanrouter.h
>  header-y += watchdog.h
> diff --git a/include/uapi/linux/vtpm.h b/include/uapi/linux/vtpm.h
> new file mode 100644
> index 0000000..4adc486
> --- /dev/null
> +++ b/include/uapi/linux/vtpm.h
> @@ -0,0 +1,41 @@
> +/*
> + * Definitions for the VTPM interface
> + * 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_H
> +#define _UAPI_LINUX_VTPM_H
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +/* ioctls */
> +
> +struct vtpm_new_dev {
> +	__u32 flags;         /* input */
> +	__u32 dev_num;       /* output */
> +	__u32 fd;            /* output */
> +	__u32 major;         /* output */
> +	__u32 minor;         /* output */
> +};
> +
> +/* above flags */
> +#define VTPM_FLAG_TPM2           1  /* emulator is TPM 2 */
> +
> +/* all supported flags */
> +#define VTPM_FLAGS_ALL  (VTPM_FLAG_TPM2)
> +
> +#define VTPM_TPM 0xa0
> +
> +#define VTPM_NEW_DEV         _IOW(VTPM_TPM, 0x00, struct vtpm_new_dev)

I'd rather use VTPM_IOC_NEW_DEV.

> +
> +#endif /* _UAPI_LINUX_VTPM_H */
> -- 
> 2.4.3

/Jarkko
 

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> On Wed, Mar 09, 2016 at 12:39:27PM -0500, Stefan Berger wrote:
 > > This patch implements a 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.
 >
 > I wrote my first test program 'tpm2-simulator-vtpm' that at the moment
 > opens /dev/vtpmx and creates a device. As next step I'm going to
 > extend this script to connect MS TPM 2.0 simulator based on the work
 > by Peter Huewe.
 >
 > It is available here:
 >
 > git://git.infradead.org/users/jjs/tpm2-scripts.git
 >
 > The first obvious thing that I observed is that the device is closed
 > when /dev/vtpmx is closed.

I don't see how closing the /dev/vtpmx file descriptor would influence 
the device pair, if that's what you are referring to with 'device'? I 
tried that with vtpmctrl.c and the device pair stays unaffected. When 
the applications terminates, the device disappears, unless the server 
side file descriptor has been passed to an external program, so that is 
expected behavior.

 >
 > Some might want to use this in a way that the created virtual device
 > is not closed when /dev/vtpmx is closed.

I don't see that happening. If you want the device pair to stay around 
after an application terminates, you have to pass the file descriptor 
returned from the ioctl to an application.

     Stefan



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On 03/10/2016 11:39 AM, Jarkko Sakkinen wrote:
> +/* above flags */
> +#define VTPM_FLAG_TPM2           1  /* emulator is TPM 2 */
> +
> +/* all supported flags */
> +#define VTPM_FLAGS_ALL  (VTPM_FLAG_TPM2)
> +
> +#define VTPM_TPM 0xa0
> +
> +#define VTPM_NEW_DEV         _IOW(VTPM_TPM, 0x00, struct vtpm_new_dev)
> I'd rather use VTPM_IOC_NEW_DEV.

What about the name of the structure ? vtpm_ioc_new_dev?

    Stefan


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On Thu, Mar 10, 2016 at 06:39:15PM +0200, Jarkko Sakkinen wrote:
> Some might want to use this in a way that the created virtual device
> is not closed when /dev/vtpmx is closed.

No, there is no reason to create an API like that - TPM's are
stateful, one cannot close the server side and re-connect and expect
things to continue to work.

Jason

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On Thu, Mar 10, 2016 at 12:30:44PM -0500, Stefan Berger wrote:
> > Some might want to use this in a way that the created virtual device
> > is not closed when /dev/vtpmx is closed.
> 
> I don't see that happening. If you want the device pair to stay around after
> an application terminates, you have to pass the file descriptor returned
> from the ioctl to an application.

Right, so it is. So the device pair dissappears either by closing the
returned fd (by the ioctl) or when application terminates. No extra
ioctls would be needed.

>     Stefan

/Jarkko

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On Thu, Mar 10, 2016 at 12:32:15PM -0500, Stefan Berger wrote:
> On 03/10/2016 11:39 AM, Jarkko Sakkinen wrote:
> >+/* above flags */
> >+#define VTPM_FLAG_TPM2           1  /* emulator is TPM 2 */
> >+
> >+/* all supported flags */
> >+#define VTPM_FLAGS_ALL  (VTPM_FLAG_TPM2)
> >+
> >+#define VTPM_TPM 0xa0

A better name would be VTPM_IOC_MAGIC. You should also update
Documentation/ioctl/ioctl-number.txt.

> >+
> >+#define VTPM_NEW_DEV         _IOW(VTPM_TPM, 0x00, struct vtpm_new_dev)
> >I'd rather use VTPM_IOC_NEW_DEV.
> 
> What about the name of the structure ? vtpm_ioc_new_dev?

If I look at other subsystems like drm the common practice is either
name the ioctl as VTPM_NEW_DEV_IOCTL or VTPM_IOC_NEW_DEV and not have
suffix or postfix in the parameter struct. I would just copy that
convention here.

>    Stefan

/Jarkko

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