tpm: Proxy driver for supporting multiple emulated TPMs

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.

The driver retrievs the TPM 1.2 durations and timeouts. Since this requires
the startup of the TPM, we send a startup for TPM 1.2 as well as TPM 2.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>

CC: linux-kernel@vger.kernel.org
CC: linux-doc@vger.kernel.org
CC: linux-api@vger.kernel.org
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

3 files changed, 655 insertions, 0 deletions

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 3b84a8b1bfbe..0eac596e33d1 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 56e8f1f3dc7e..98de5e676f3c 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 000000000000..4384042b3b50
--- /dev/null
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -0,0 +1,644 @@
+/*
+ * 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 */
+
+	struct work_struct work;     /* task that retrieves TPM timeouts */
+};
+
+/* all supported flags */
+#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2)
+
+static struct workqueue_struct *workqueue;
+
+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 ||
+		!(proxy_dev->state & STATE_OPENED_FLAG));
+	if (sig)
+		return -EINTR;
+
+	mutex_lock(&proxy_dev->buf_lock);
+
+	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EPIPE;
+	}
+
+	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 (!(proxy_dev->state & STATE_OPENED_FLAG)) {
+		mutex_unlock(&proxy_dev->buf_lock);
+		return -EPIPE;
+	}
+
+	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;
+
+	if (!(proxy_dev->state & STATE_OPENED_FLAG))
+		ret |= POLLHUP;
+
+	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 = dev_get_drvdata(&chip->dev);
+	size_t len;
+
+	/* 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 = dev_get_drvdata(&chip->dev);
+	int rc = 0;
+
+	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 = dev_get_drvdata(&chip->dev);
+
+	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 = dev_get_drvdata(&chip->dev);
+	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 the startup of the TPM 2 and startup of TPM 1.2 +
+ * retrieval of timeouts and durations.
+ */
+
+static void vtpm_proxy_work(struct work_struct *work)
+{
+	struct proxy_dev *proxy_dev = container_of(work, struct proxy_dev,
+						   work);
+	int rc;
+
+	if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
+		rc = tpm2_startup(proxy_dev->chip, TPM2_SU_CLEAR);
+	else
+		rc = tpm_get_timeouts(proxy_dev->chip);
+
+	if (rc)
+		goto err;
+
+	rc = tpm_chip_register(proxy_dev->chip);
+	if (rc)
+		goto err;
+
+	return;
+
+err:
+	vtpm_proxy_fops_undo_open(proxy_dev);
+}
+
+/*
+ * vtpm_proxy_work_stop: make sure the work has finished
+ *
+ * This function is useful when user space closed the fd
+ * while the driver still determines timeouts.
+ */
+static void vtpm_proxy_work_stop(struct proxy_dev *proxy_dev)
+{
+	vtpm_proxy_fops_undo_open(proxy_dev);
+	flush_work(&proxy_dev->work);
+}
+
+/*
+ * vtpm_proxy_work_start: Schedule the work for TPM 1.2 & 2 initialization
+ */
+static inline void vtpm_proxy_work_start(struct proxy_dev *proxy_dev)
+{
+	queue_work(workqueue, &proxy_dev->work);
+}
+
+/*
+ * 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);
+	INIT_WORK(&proxy_dev->work, vtpm_proxy_work);
+
+	chip = tpm_chip_alloc(NULL, &vtpm_proxy_tpm_ops);
+	if (IS_ERR(chip)) {
+		err = PTR_ERR(chip);
+		goto err_proxy_dev_free;
+	}
+	dev_set_drvdata(&chip->dev, 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;
+
+	vtpm_proxy_work_start(proxy_dev);
+
+	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_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)
+{
+	vtpm_proxy_work_stop(proxy_dev);
+
+	/*
+	 * A client may hold the 'ops' lock, so let it know that the server
+	 * side shuts down before we try to grab the 'ops' lock when
+	 * unregistering the chip.
+	 */
+	vtpm_proxy_fops_undo_open(proxy_dev);
+
+	tpm_chip_unregister(proxy_dev->chip);
+
+	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;
+	}
+
+	workqueue = create_workqueue("tpm-vtpm");
+	if (!workqueue) {
+		pr_err("couldn't create workqueue\n");
+		rc = -ENOMEM;
+		goto err_vtpmx_cleanup;
+	}
+
+	return 0;
+
+err_vtpmx_cleanup:
+	vtpmx_cleanup();
+
+	return rc;
+}
+
+static void __exit vtpm_module_exit(void)
+{
+	destroy_workqueue(workqueue);
+	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");