This is a complete rewrite of the Xen TPM frontend driver, taking
advantage of a simplified frontend/backend interface and adding support
for cancellation and timeouts. The backend for this driver is provided
by a vTPM stub domain using the interface in Xen 4.3.
Signed-off-by: Daniel De Graaf <[email protected]>
Acked-by: Matthew Fioravante <[email protected]>
Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
Acked-by: Peter Huewe <[email protected]>
Reviewed-by: Peter Huewe <[email protected]>
---
Changes from v3:
- Fixed some textual header information (copyrights)
- Use a better error value when sending an overlarge packet
Documentation/xen-tpmfront.txt | 113 ++++++++++
drivers/char/tpm/Kconfig | 11 +
drivers/char/tpm/Makefile | 1 +
drivers/char/tpm/xen-tpmfront.c | 470 +++++++++++++++++++++++++++++++++++++++
include/xen/interface/io/tpmif.h | 34 +++
5 files changed, 629 insertions(+)
create mode 100644 Documentation/xen-tpmfront.txt
create mode 100644 drivers/char/tpm/xen-tpmfront.c
create mode 100644 include/xen/interface/io/tpmif.h
diff --git a/Documentation/xen-tpmfront.txt b/Documentation/xen-tpmfront.txt
new file mode 100644
index 0000000..69346de
--- /dev/null
+++ b/Documentation/xen-tpmfront.txt
@@ -0,0 +1,113 @@
+Virtual TPM interface for Xen
+
+Authors: Matthew Fioravante (JHUAPL), Daniel De Graaf (NSA)
+
+This document describes the virtual Trusted Platform Module (vTPM) subsystem for
+Xen. The reader is assumed to have familiarity with building and installing Xen,
+Linux, and a basic understanding of the TPM and vTPM concepts.
+
+INTRODUCTION
+
+The goal of this work is to provide a TPM functionality to a virtual guest
+operating system (in Xen terms, a DomU). This allows programs to interact with
+a TPM in a virtual system the same way they interact with a TPM on the physical
+system. Each guest gets its own unique, emulated, software TPM. However, each
+of the vTPM's secrets (Keys, NVRAM, etc) are managed by a vTPM Manager domain,
+which seals the secrets to the Physical TPM. If the process of creating each of
+these domains (manager, vTPM, and guest) is trusted, the vTPM subsystem extends
+the chain of trust rooted in the hardware TPM to virtual machines in Xen. Each
+major component of vTPM is implemented as a separate domain, providing secure
+separation guaranteed by the hypervisor. The vTPM domains are implemented in
+mini-os to reduce memory and processor overhead.
+
+This mini-os vTPM subsystem was built on top of the previous vTPM work done by
+IBM and Intel corporation.
+
+
+DESIGN OVERVIEW
+---------------
+
+The architecture of vTPM is described below:
+
++------------------+
+| Linux DomU | ...
+| | ^ |
+| v | |
+| xen-tpmfront |
++------------------+
+ | ^
+ v |
++------------------+
+| mini-os/tpmback |
+| | ^ |
+| v | |
+| vtpm-stubdom | ...
+| | ^ |
+| v | |
+| mini-os/tpmfront |
++------------------+
+ | ^
+ v |
++------------------+
+| mini-os/tpmback |
+| | ^ |
+| v | |
+| vtpmmgr-stubdom |
+| | ^ |
+| v | |
+| mini-os/tpm_tis |
++------------------+
+ | ^
+ v |
++------------------+
+| Hardware TPM |
++------------------+
+
+ * Linux DomU: The Linux based guest that wants to use a vTPM. There may be
+ more than one of these.
+
+ * xen-tpmfront.ko: Linux kernel virtual TPM frontend driver. This driver
+ provides vTPM access to a Linux-based DomU.
+
+ * mini-os/tpmback: Mini-os TPM backend driver. The Linux frontend driver
+ connects to this backend driver to facilitate communications
+ between the Linux DomU and its vTPM. This driver is also
+ used by vtpmmgr-stubdom to communicate with vtpm-stubdom.
+
+ * vtpm-stubdom: A mini-os stub domain that implements a vTPM. There is a
+ one to one mapping between running vtpm-stubdom instances and
+ logical vtpms on the system. The vTPM Platform Configuration
+ Registers (PCRs) are normally all initialized to zero.
+
+ * mini-os/tpmfront: Mini-os TPM frontend driver. The vTPM mini-os domain
+ vtpm-stubdom uses this driver to communicate with
+ vtpmmgr-stubdom. This driver is also used in mini-os
+ domains such as pv-grub that talk to the vTPM domain.
+
+ * vtpmmgr-stubdom: A mini-os domain that implements the vTPM manager. There is
+ only one vTPM manager and it should be running during the
+ entire lifetime of the machine. This domain regulates
+ access to the physical TPM on the system and secures the
+ persistent state of each vTPM.
+
+ * mini-os/tpm_tis: Mini-os TPM version 1.2 TPM Interface Specification (TIS)
+ driver. This driver used by vtpmmgr-stubdom to talk directly to
+ the hardware TPM. Communication is facilitated by mapping
+ hardware memory pages into vtpmmgr-stubdom.
+
+ * Hardware TPM: The physical TPM that is soldered onto the motherboard.
+
+
+INTEGRATION WITH XEN
+--------------------
+
+Support for the vTPM driver was added in Xen using the libxl toolstack in Xen
+4.3. See the Xen documentation (docs/misc/vtpm.txt) for details on setting up
+the vTPM and vTPM Manager stub domains. Once the stub domains are running, a
+vTPM device is set up in the same manner as a disk or network device in the
+domain's configuration file.
+
+In order to use features such as IMA that require a TPM to be loaded prior to
+the initrd, the xen-tpmfront driver must be compiled in to the kernel. If not
+using such features, the driver can be compiled as a module and will be loaded
+as usual.
diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index dbfd564..205ed35 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -91,4 +91,15 @@ config TCG_ST33_I2C
To compile this driver as a module, choose M here; the module will be
called tpm_stm_st33_i2c.
+config TCG_XEN
+ tristate "XEN TPM Interface"
+ depends on TCG_TPM && XEN
+ ---help---
+ If you want to make TPM support available to a Xen user domain,
+ say Yes and it will be accessible from within Linux. See
+ the manpages for xl, xl.conf, and docs/misc/vtpm.txt in
+ the Xen source repository for more details.
+ To compile this driver as a module, choose M here; the module
+ will be called xen-tpmfront.
+
endif # TCG_TPM
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index a3736c9..eb41ff9 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_TCG_ATMEL) += tpm_atmel.o
obj-$(CONFIG_TCG_INFINEON) += tpm_infineon.o
obj-$(CONFIG_TCG_IBMVTPM) += tpm_ibmvtpm.o
obj-$(CONFIG_TCG_ST33_I2C) += tpm_i2c_stm_st33.o
+obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
new file mode 100644
index 0000000..7f2f13d
--- /dev/null
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -0,0 +1,470 @@
+/*
+ * Implementation of the Xen vTPM device frontend
+ *
+ * Author: Daniel De Graaf <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <xen/events.h>
+#include <xen/interface/io/tpmif.h>
+#include <xen/grant_table.h>
+#include <xen/xenbus.h>
+#include <xen/page.h>
+#include "tpm.h"
+
+struct tpm_private {
+ struct tpm_chip *chip;
+ struct xenbus_device *dev;
+
+ struct vtpm_shared_page *shr;
+
+ unsigned int evtchn;
+ int ring_ref;
+ domid_t backend_id;
+};
+
+enum status_bits {
+ VTPM_STATUS_RUNNING = 0x1,
+ VTPM_STATUS_IDLE = 0x2,
+ VTPM_STATUS_RESULT = 0x4,
+ VTPM_STATUS_CANCELED = 0x8,
+};
+
+static u8 vtpm_status(struct tpm_chip *chip)
+{
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ switch (priv->shr->state) {
+ case VTPM_STATE_IDLE:
+ return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
+ case VTPM_STATE_FINISH:
+ return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
+ case VTPM_STATE_SUBMIT:
+ case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
+ return VTPM_STATUS_RUNNING;
+ default:
+ return 0;
+ }
+}
+
+static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
+{
+ return status & VTPM_STATUS_CANCELED;
+}
+
+static void vtpm_cancel(struct tpm_chip *chip)
+{
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ priv->shr->state = VTPM_STATE_CANCEL;
+ wmb();
+ notify_remote_via_evtchn(priv->evtchn);
+}
+
+static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
+{
+ return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
+}
+
+static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ struct vtpm_shared_page *shr = priv->shr;
+ unsigned int offset = shr_data_offset(shr);
+
+ u32 ordinal;
+ unsigned long duration;
+
+ if (offset > PAGE_SIZE)
+ return -EINVAL;
+
+ if (offset + count > PAGE_SIZE)
+ return -EINVAL;
+
+ /* Wait for completion of any existing command or cancellation */
+ if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
+ &chip->vendor.read_queue, true) < 0) {
+ vtpm_cancel(chip);
+ return -ETIME;
+ }
+
+ memcpy(offset + (u8 *)shr, buf, count);
+ shr->length = count;
+ barrier();
+ shr->state = VTPM_STATE_SUBMIT;
+ wmb();
+ notify_remote_via_evtchn(priv->evtchn);
+
+ ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
+ duration = tpm_calc_ordinal_duration(chip, ordinal);
+
+ if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
+ &chip->vendor.read_queue, true) < 0) {
+ /* got a signal or timeout, try to cancel */
+ vtpm_cancel(chip);
+ return -ETIME;
+ }
+
+ return count;
+}
+
+static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ struct vtpm_shared_page *shr = priv->shr;
+ unsigned int offset = shr_data_offset(shr);
+ size_t length = shr->length;
+
+ if (shr->state == VTPM_STATE_IDLE)
+ return -ECANCELED;
+
+ /* In theory the wait at the end of _send makes this one unnecessary */
+ if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
+ &chip->vendor.read_queue, true) < 0) {
+ vtpm_cancel(chip);
+ return -ETIME;
+ }
+
+ if (offset > PAGE_SIZE)
+ return -EIO;
+
+ if (offset + length > PAGE_SIZE)
+ length = PAGE_SIZE - offset;
+
+ if (length > count)
+ length = count;
+
+ memcpy(buf, offset + (u8 *)shr, length);
+
+ return length;
+}
+
+ssize_t tpm_show_locality(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct tpm_chip *chip = dev_get_drvdata(dev);
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ u8 locality = priv->shr->locality;
+
+ return sprintf(buf, "%d\n", locality);
+}
+
+ssize_t tpm_store_locality(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct tpm_chip *chip = dev_get_drvdata(dev);
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ u8 val;
+
+ int rv = kstrtou8(buf, 0, &val);
+ if (rv)
+ return rv;
+
+ priv->shr->locality = val;
+
+ return len;
+}
+
+static const struct file_operations vtpm_ops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .open = tpm_open,
+ .read = tpm_read,
+ .write = tpm_write,
+ .release = tpm_release,
+};
+
+static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
+static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
+static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
+static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
+static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
+static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated,
+ NULL);
+static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
+static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
+static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
+static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
+static DEVICE_ATTR(locality, S_IRUGO | S_IWUSR, tpm_show_locality,
+ tpm_store_locality);
+
+static struct attribute *vtpm_attrs[] = {
+ &dev_attr_pubek.attr,
+ &dev_attr_pcrs.attr,
+ &dev_attr_enabled.attr,
+ &dev_attr_active.attr,
+ &dev_attr_owned.attr,
+ &dev_attr_temp_deactivated.attr,
+ &dev_attr_caps.attr,
+ &dev_attr_cancel.attr,
+ &dev_attr_durations.attr,
+ &dev_attr_timeouts.attr,
+ &dev_attr_locality.attr,
+ NULL,
+};
+
+static struct attribute_group vtpm_attr_grp = {
+ .attrs = vtpm_attrs,
+};
+
+#define TPM_LONG_TIMEOUT (10 * 60 * HZ)
+
+static const struct tpm_vendor_specific tpm_vtpm = {
+ .status = vtpm_status,
+ .recv = vtpm_recv,
+ .send = vtpm_send,
+ .cancel = vtpm_cancel,
+ .req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
+ .req_complete_val = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
+ .req_canceled = vtpm_req_canceled,
+ .attr_group = &vtpm_attr_grp,
+ .miscdev = {
+ .fops = &vtpm_ops,
+ },
+ .duration = {
+ TPM_LONG_TIMEOUT,
+ TPM_LONG_TIMEOUT,
+ TPM_LONG_TIMEOUT,
+ },
+};
+
+static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
+{
+ struct tpm_private *priv = dev_id;
+
+ switch (priv->shr->state) {
+ case VTPM_STATE_IDLE:
+ case VTPM_STATE_FINISH:
+ wake_up_interruptible(&priv->chip->vendor.read_queue);
+ break;
+ case VTPM_STATE_SUBMIT:
+ case VTPM_STATE_CANCEL:
+ default:
+ break;
+ }
+ return IRQ_HANDLED;
+}
+
+static int setup_chip(struct device *dev, struct tpm_private *priv)
+{
+ struct tpm_chip *chip;
+
+ chip = tpm_register_hardware(dev, &tpm_vtpm);
+ if (!chip)
+ return -ENODEV;
+
+ init_waitqueue_head(&chip->vendor.read_queue);
+
+ priv->chip = chip;
+ TPM_VPRIV(chip) = priv;
+
+ return 0;
+}
+
+/* caller must clean up in case of errors */
+static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
+{
+ struct xenbus_transaction xbt;
+ const char *message = NULL;
+ int rv;
+
+ priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
+ if (!priv->shr) {
+ xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
+ return -ENOMEM;
+ }
+
+ rv = xenbus_grant_ring(dev, virt_to_mfn(priv->shr));
+ if (rv < 0)
+ return rv;
+
+ priv->ring_ref = rv;
+
+ rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
+ if (rv)
+ return rv;
+
+ rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
+ "tpmif", priv);
+ if (rv <= 0) {
+ xenbus_dev_fatal(dev, rv, "allocating TPM irq");
+ return rv;
+ }
+ priv->chip->vendor.irq = rv;
+
+ again:
+ rv = xenbus_transaction_start(&xbt);
+ if (rv) {
+ xenbus_dev_fatal(dev, rv, "starting transaction");
+ return rv;
+ }
+
+ rv = xenbus_printf(xbt, dev->nodename,
+ "ring-ref", "%u", priv->ring_ref);
+ if (rv) {
+ message = "writing ring-ref";
+ goto abort_transaction;
+ }
+
+ rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
+ priv->evtchn);
+ if (rv) {
+ message = "writing event-channel";
+ goto abort_transaction;
+ }
+
+ rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
+ if (rv) {
+ message = "writing feature-protocol-v2";
+ goto abort_transaction;
+ }
+
+ rv = xenbus_transaction_end(xbt, 0);
+ if (rv == -EAGAIN)
+ goto again;
+ if (rv) {
+ xenbus_dev_fatal(dev, rv, "completing transaction");
+ return rv;
+ }
+
+ xenbus_switch_state(dev, XenbusStateInitialised);
+
+ return 0;
+
+ abort_transaction:
+ xenbus_transaction_end(xbt, 1);
+ if (message)
+ xenbus_dev_error(dev, rv, "%s", message);
+
+ return rv;
+}
+
+static void ring_free(struct tpm_private *priv)
+{
+ if (!priv)
+ return;
+
+ if (priv->ring_ref)
+ gnttab_end_foreign_access(priv->ring_ref, 0,
+ (unsigned long)priv->shr);
+ else
+ free_page((unsigned long)priv->shr);
+
+ if (priv->chip && priv->chip->vendor.irq)
+ unbind_from_irqhandler(priv->chip->vendor.irq, priv);
+
+ kfree(priv);
+}
+
+static int tpmfront_probe(struct xenbus_device *dev,
+ const struct xenbus_device_id *id)
+{
+ struct tpm_private *priv;
+ int rv;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv) {
+ xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
+ return -ENOMEM;
+ }
+
+ rv = setup_chip(&dev->dev, priv);
+ if (rv) {
+ kfree(priv);
+ return rv;
+ }
+
+ rv = setup_ring(dev, priv);
+ if (rv) {
+ tpm_remove_hardware(&dev->dev);
+ ring_free(priv);
+ return rv;
+ }
+
+ tpm_get_timeouts(priv->chip);
+
+ dev_set_drvdata(&dev->dev, priv->chip);
+
+ return rv;
+}
+
+static int tpmfront_remove(struct xenbus_device *dev)
+{
+ struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
+ struct tpm_private *priv = TPM_VPRIV(chip);
+ tpm_remove_hardware(&dev->dev);
+ ring_free(priv);
+ TPM_VPRIV(chip) = NULL;
+ return 0;
+}
+
+static int tpmfront_resume(struct xenbus_device *dev)
+{
+ /* A suspend/resume/migrate will interrupt a vTPM anyway */
+ tpmfront_remove(dev);
+ return tpmfront_probe(dev, NULL);
+}
+
+static void backend_changed(struct xenbus_device *dev,
+ enum xenbus_state backend_state)
+{
+ int val;
+
+ switch (backend_state) {
+ case XenbusStateInitialised:
+ case XenbusStateConnected:
+ if (xenbus_scanf(XBT_NIL, dev->otherend,
+ "feature-protocol-v2", "%d", &val) < 0)
+ val = 0;
+ if (!val) {
+ xenbus_dev_fatal(dev, -EINVAL,
+ "vTPM protocol 2 required");
+ return;
+ }
+ xenbus_switch_state(dev, XenbusStateConnected);
+ break;
+
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ device_unregister(&dev->dev);
+ xenbus_frontend_closed(dev);
+ break;
+ default:
+ break;
+ }
+}
+
+static const struct xenbus_device_id tpmfront_ids[] = {
+ { "vtpm" },
+ { "" }
+};
+MODULE_ALIAS("xen:vtpm");
+
+static DEFINE_XENBUS_DRIVER(tpmfront, ,
+ .probe = tpmfront_probe,
+ .remove = tpmfront_remove,
+ .resume = tpmfront_resume,
+ .otherend_changed = backend_changed,
+ );
+
+static int __init xen_tpmfront_init(void)
+{
+ if (!xen_domain())
+ return -ENODEV;
+
+ return xenbus_register_frontend(&tpmfront_driver);
+}
+module_init(xen_tpmfront_init);
+
+static void __exit xen_tpmfront_exit(void)
+{
+ xenbus_unregister_driver(&tpmfront_driver);
+}
+module_exit(xen_tpmfront_exit);
+
+MODULE_AUTHOR("Daniel De Graaf <[email protected]>");
+MODULE_DESCRIPTION("Xen vTPM Driver");
+MODULE_LICENSE("GPL");
diff --git a/include/xen/interface/io/tpmif.h b/include/xen/interface/io/tpmif.h
new file mode 100644
index 0000000..33f982b
--- /dev/null
+++ b/include/xen/interface/io/tpmif.h
@@ -0,0 +1,34 @@
+/******************************************************************************
+ * tpmif.h
+ *
+ * TPM I/O interface for Xen guest OSes, v2
+ *
+ * This file is in the public domain.
+ *
+ */
+
+#ifndef __XEN_PUBLIC_IO_TPMIF_H__
+#define __XEN_PUBLIC_IO_TPMIF_H__
+
+enum vtpm_shared_page_state {
+ VTPM_STATE_IDLE, /* no contents / vTPM idle / cancel complete */
+ VTPM_STATE_SUBMIT, /* request ready / vTPM working */
+ VTPM_STATE_FINISH, /* response ready / vTPM idle */
+ VTPM_STATE_CANCEL, /* cancel requested / vTPM working */
+};
+/* The backend should only change state to IDLE or FINISH, while the
+ * frontend should only change to SUBMIT or CANCEL. */
+
+
+struct vtpm_shared_page {
+ uint32_t length; /* request/response length in bytes */
+
+ uint8_t state; /* enum vtpm_shared_page_state */
+ uint8_t locality; /* for the current request */
+ uint8_t pad;
+
+ uint8_t nr_extra_pages; /* extra pages for long packets; may be zero */
+ uint32_t extra_pages[0]; /* grant IDs; length in nr_extra_pages */
+};
+
+#endif
--
1.8.1.4
Am Montag, 1. Juli 2013, 23:34:28 schrieb Daniel De Graaf:
> This is a complete rewrite of the Xen TPM frontend driver, taking
> advantage of a simplified frontend/backend interface and adding support
> for cancellation and timeouts. The backend for this driver is provided
> by a vTPM stub domain using the interface in Xen 4.3.
>
> Signed-off-by: Daniel De Graaf <[email protected]>
> Acked-by: Matthew Fioravante <[email protected]>
> Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
> Acked-by: Peter Huewe <[email protected]>
> Reviewed-by: Peter Huewe <[email protected]>
> ---
Reviewed, the remaining topics were addressed in this v4.
Reviewed-by: Peter Huewe <[email protected]>
>From the TPM point of view I'd say it is fine.
Acked-by: Peter Huewe <[email protected]>
Thanks!
@Konrad: Can you take it through your tree?
Thanks,
Peter
"Peter Hüwe" <[email protected]> wrote:
>Am Montag, 1. Juli 2013, 23:34:28 schrieb Daniel De Graaf:
>> This is a complete rewrite of the Xen TPM frontend driver, taking
>> advantage of a simplified frontend/backend interface and adding
>support
>> for cancellation and timeouts. The backend for this driver is
>provided
>> by a vTPM stub domain using the interface in Xen 4.3.
>>
>> Signed-off-by: Daniel De Graaf <[email protected]>
>> Acked-by: Matthew Fioravante <[email protected]>
>> Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
>> Acked-by: Peter Huewe <[email protected]>
>> Reviewed-by: Peter Huewe <[email protected]>
>> ---
>
>Reviewed, the remaining topics were addressed in this v4.
>Reviewed-by: Peter Huewe <[email protected]>
>
>
>From the TPM point of view I'd say it is fine.
>Acked-by: Peter Huewe <[email protected]>
>
>Thanks!
>
>@Konrad: Can you take it through your tree?
>
>
>Thanks,
>Peter
Of course I will queue it up. I am not sure if it will be able to make it in 3.11 (merge window opened just now).
--
Sent from my Android phone. Please excuse my brevity.
On 01/07/13 22:34, Daniel De Graaf wrote:
> This is a complete rewrite of the Xen TPM frontend driver, taking
> advantage of a simplified frontend/backend interface and adding support
> for cancellation and timeouts. The backend for this driver is provided
> by a vTPM stub domain using the interface in Xen 4.3.
[...]
> --- /dev/null
> +++ b/Documentation/xen-tpmfront.txt
Suggest putting this in Documentation/tpm/.
> --- /dev/null
> +++ b/drivers/char/tpm/xen-tpmfront.c
[...]
> +static void backend_changed(struct xenbus_device *dev,
> + enum xenbus_state backend_state)
> +{
> + int val;
Hrm. I don't like how every front/back pair invents their own variation
of the state machine.
Please document the front and back state machines in
xen/include/public/io/tpmif.h (and the correspoding copy in Linux).
> +
> + switch (backend_state) {
> + case XenbusStateInitialised:
> + case XenbusStateConnected:
if (dev->state == XenbusStateConnected)
break;
Perhaps?
> + if (xenbus_scanf(XBT_NIL, dev->otherend,
> + "feature-protocol-v2", "%d", &val) < 0)
> + val = 0;
> + if (!val) {
> + xenbus_dev_fatal(dev, -EINVAL,
> + "vTPM protocol 2 required");
> + return;
> + }
> + xenbus_switch_state(dev, XenbusStateConnected);
> + break;
> +
> + case XenbusStateClosing:
> + case XenbusStateClosed:
> + device_unregister(&dev->dev);
> + xenbus_frontend_closed(dev);
> + break;
> + default:
> + break;
> + }
> +}
David
On 07/22/2013 11:18 AM, David Vrabel wrote:
> On 01/07/13 22:34, Daniel De Graaf wrote:
>> This is a complete rewrite of the Xen TPM frontend driver, taking
>> advantage of a simplified frontend/backend interface and adding support
>> for cancellation and timeouts. The backend for this driver is provided
>> by a vTPM stub domain using the interface in Xen 4.3.
> [...]
>> --- /dev/null
>> +++ b/Documentation/xen-tpmfront.txt
>
> Suggest putting this in Documentation/tpm/.
OK.
>> --- /dev/null
>> +++ b/drivers/char/tpm/xen-tpmfront.c
> [...]
>> +static void backend_changed(struct xenbus_device *dev,
>> + enum xenbus_state backend_state)
>> +{
>> + int val;
>
> Hrm. I don't like how every front/back pair invents their own variation
> of the state machine.
>
> Please document the front and back state machines in
> xen/include/public/io/tpmif.h (and the correspoding copy in Linux).
Is there a standard state machine that would allow devices to avoid
inventing their own?
Otherwise, this is what I plan to add to the header:
/*
* Xenbus state machine
*
* Device open:
* 1. Both ends start in XenbusStateInitialising
* 2. Backend transitions to InitWait (frontend does not wait on this step)
* 3. Frontend populates ring-ref, event-channel, feature-protocol-v2
* 4. Frontend transitions to Initialised
* 5. Backend maps grant and event channel, verifies feature-protocol-v2
* 6. Backend transitions to Connected
* 7. Frontend verifies feature-protocol-v2, transitions to Connected
*
* Device close:
* 1. State is changed to XenbusStateClosing
* 2. Frontend transitions to Closed
* 3. Backend unmaps grant and event, changes state to InitWait
*/
>> +
>> + switch (backend_state) {
>> + case XenbusStateInitialised:
>> + case XenbusStateConnected:
>
> if (dev->state == XenbusStateConnected)
> break;
>
> Perhaps?
Sure, although the spurious invocation is not seen with the mini-os
backend and running this code twice is harmless.
>> + if (xenbus_scanf(XBT_NIL, dev->otherend,
>> + "feature-protocol-v2", "%d", &val) < 0)
>> + val = 0;
>> + if (!val) {
>> + xenbus_dev_fatal(dev, -EINVAL,
>> + "vTPM protocol 2 required");
>> + return;
>> + }
>> + xenbus_switch_state(dev, XenbusStateConnected);
>> + break;
>> +
>> + case XenbusStateClosing:
>> + case XenbusStateClosed:
>> + device_unregister(&dev->dev);
>> + xenbus_frontend_closed(dev);
>> + break;
>> + default:
>> + break;
>> + }
>> +}
>
> David
--
Daniel De Graaf
National Security Agency
On 22/07/13 17:20, Daniel De Graaf wrote:
> On 07/22/2013 11:18 AM, David Vrabel wrote:
>> On 01/07/13 22:34, Daniel De Graaf wrote:
>>> This is a complete rewrite of the Xen TPM frontend driver, taking
>>> advantage of a simplified frontend/backend interface and adding support
>>> for cancellation and timeouts. The backend for this driver is provided
>>> by a vTPM stub domain using the interface in Xen 4.3.
>> [...]
>>> --- /dev/null
>>> +++ b/Documentation/xen-tpmfront.txt
>>
>> Suggest putting this in Documentation/tpm/.
>
> OK.
>
>>> --- /dev/null
>>> +++ b/drivers/char/tpm/xen-tpmfront.c
>> [...]
>>> +static void backend_changed(struct xenbus_device *dev,
>>> + enum xenbus_state backend_state)
>>> +{
>>> + int val;
>>
>> Hrm. I don't like how every front/back pair invents their own variation
>> of the state machine.
>>
>> Please document the front and back state machines in
>> xen/include/public/io/tpmif.h (and the correspoding copy in Linux).
>
> Is there a standard state machine that would allow devices to avoid
> inventing their own?
That would be nice wouldn't it? But, no, there isn't one -- even
netfront and blkfront are different.
> Otherwise, this is what I plan to add to the header:
> /*
> * Xenbus state machine
> *
> * Device open:
> * 1. Both ends start in XenbusStateInitialising
> * 2. Backend transitions to InitWait (frontend does not wait on this
> step)
> * 3. Frontend populates ring-ref, event-channel, feature-protocol-v2
> * 4. Frontend transitions to Initialised
> * 5. Backend maps grant and event channel, verifies feature-protocol-v2
> * 6. Backend transitions to Connected
> * 7. Frontend verifies feature-protocol-v2, transitions to Connected
> *
> * Device close:
> * 1. State is changed to XenbusStateClosing
> * 2. Frontend transitions to Closed
> * 3. Backend unmaps grant and event, changes state to InitWait
> */
That's good, thanks.
David