[PATCH v7 08/10] tpm: Proxy driver for supporting multiple emulated TPMs

Stefan Berger
2016-03-12T02:52:00Z

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

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