drivers/tpm: add xen tpmfront interface
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 <dgdegra@tycho.nsa.gov>
Acked-by: Matthew Fioravante <matthew.fioravante@jhuapl.edu>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Peter Huewe <peterhuewe@gmx.de>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
new file mode 100644
index 0000000..7a7929b
--- /dev/null
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -0,0 +1,473 @@
+/*
+ * Implementation of the Xen vTPM device frontend
+ *
+ * Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
+ *
+ * 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 (dev->state == XenbusStateConnected)
+ break;
+
+ 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 <dgdegra@tycho.nsa.gov>");
+MODULE_DESCRIPTION("Xen vTPM Driver");
+MODULE_LICENSE("GPL");