Re: [PATCH] drivers/tpm: add xen tpmfront interface (Re: [PATCH 01/12]...)

[Matthew Fioravante <matthew.fioravante@jhuapl.edu>]

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Daniel, this looks great. Thank you for taking the effort to rewrite 
that awful tpm driver.

The only comment I have for you which is a carry-over from my previous 
feedback from konrad is to include a copy of /docs/misc/vtpm.txt as 
Documentation/xen-tpmfront.txt, with a note of where to get the latest 
version in xen.

I believe he also asked for a copy of the entire document in the commit 
message.

Acked-by: Matthew Fioravante <matthew.fioravante@jhuapl.edu>

On 03/26/2013 12:52 PM, Daniel De Graaf wrote:
> Original subject: Re: [PATCH 01/12] mini-os/tpm{back,front}: Change shared page ABI
>
> On 03/26/2013 12:29 PM, Matthew Fioravante wrote:
>> I'm going to merge your linux changes into my working linux patch with the fixes that are in response to konrad's comments. Will test with this on the mini-os end and get back to you.
>>
>> After that, we can look at the remaining patches.
> The changes that I posted to this vTPM patch still leave a lot of the
> unneeded relics from using a packet interface for vTPM commands. The patch
> below properly uses Linux's TPM interface, and is far simpler than the
> other driver (while also supporting features such as command cancellation).
> I would prefer that this driver be considered instead of my previously
> posted patch to your forward port of the 2.6.18-xen.hg driver.
>
> I have tested this patch with HVM and PV guests, interfacing with a mini-os
> vTPM using my patches. The PV guest was tested both with and without pv-grub
> loading the kernel and using the vTPM to report measurements.
>
> ---------------------8<--------------------------------------
> [PATCH] 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.
>
> Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
> ---
> This patch is based off Linux 3.9-rc4
>
>    drivers/char/tpm/Kconfig         |  11 +
>    drivers/char/tpm/Makefile        |   1 +
>    drivers/char/tpm/xen-tpmfront.c  | 423 +++++++++++++++++++++++++++++++++++++++
>    include/xen/interface/io/tpmif.h |  50 +++++
>    4 files changed, 485 insertions(+)
>    create mode 100644 drivers/char/tpm/xen-tpmfront.c
>    create mode 100644 include/xen/interface/io/tpmif.h
>
> 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..1eb8de1
> --- /dev/null
> +++ b/drivers/char/tpm/xen-tpmfront.c
> @@ -0,0 +1,423 @@
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/mutex.h>
> +#include <linux/uaccess.h>
> +#include <xen/events.h>
> +#include <xen/interface/grant_table.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;
> +       notify_remote_via_evtchn(priv->evtchn);
> +}
> +
> +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 = sizeof(*shr) + 4*shr->nr_extra_pages;
> +
> +       u32 ordinal;
> +       unsigned long duration;
> +
> +       if (count < TPM_HEADER_SIZE)
> +               return -EIO;
> +
> +       if (offset > PAGE_SIZE)
> +               return -EIO;
> +
> +       if (offset + count > PAGE_SIZE)
> +               return -EIO;
> +
> +       /* 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;
> +       notify_remote_via_evtchn(priv->evtchn);
> +
> +       ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
> +       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 = sizeof(*shr) + 4*shr->nr_extra_pages;
> +       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, count);
> +
> +       return length;
> +}
> +
> +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 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,
> +       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;
> +}
> +
> +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->ring_ref)
> +               gnttab_end_foreign_access(priv->ring_ref, 0,
> +                               (unsigned long)priv->shr);
> +
> +       if (priv->chip && priv->chip->vendor.irq)
> +               unbind_from_irqhandler(priv->chip->vendor.irq, priv);
> +
> +       free_page((unsigned long)priv->shr);
> +       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);
> +       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_LICENSE("Dual BSD/GPL");
> diff --git a/include/xen/interface/io/tpmif.h b/include/xen/interface/io/tpmif.h
> new file mode 100644
> index 0000000..92522a4
> --- /dev/null
> +++ b/include/xen/interface/io/tpmif.h
> @@ -0,0 +1,50 @@
> +/******************************************************************************
> + * tpmif.h
> + *
> + * TPM I/O interface for Xen guest OSes, v2
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to
> + * deal in the Software without restriction, including without limitation the
> + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
> + * sell copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> + * DEALINGS IN THE SOFTWARE.
> + *
> + */
> +
> +#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
>



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