458 lines
9.8 KiB
C
458 lines
9.8 KiB
C
/*
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* Implementation of the Xen vTPM device frontend
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*
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* Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2,
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* as published by the Free Software Foundation.
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*/
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/interrupt.h>
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#include <linux/freezer.h>
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#include <xen/xen.h>
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#include <xen/events.h>
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#include <xen/interface/io/tpmif.h>
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#include <xen/grant_table.h>
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#include <xen/xenbus.h>
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#include <xen/page.h>
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#include "tpm.h"
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#include <xen/platform_pci.h>
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struct tpm_private {
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struct tpm_chip *chip;
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struct xenbus_device *dev;
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struct vtpm_shared_page *shr;
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unsigned int evtchn;
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int ring_ref;
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domid_t backend_id;
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int irq;
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wait_queue_head_t read_queue;
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};
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enum status_bits {
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VTPM_STATUS_RUNNING = 0x1,
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VTPM_STATUS_IDLE = 0x2,
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VTPM_STATUS_RESULT = 0x4,
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VTPM_STATUS_CANCELED = 0x8,
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};
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static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
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bool check_cancel, bool *canceled)
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{
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u8 status = chip->ops->status(chip);
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*canceled = false;
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if ((status & mask) == mask)
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return true;
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if (check_cancel && chip->ops->req_canceled(chip, status)) {
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*canceled = true;
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return true;
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}
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return false;
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}
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static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
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unsigned long timeout, wait_queue_head_t *queue,
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bool check_cancel)
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{
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unsigned long stop;
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long rc;
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u8 status;
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bool canceled = false;
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/* check current status */
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status = chip->ops->status(chip);
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if ((status & mask) == mask)
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return 0;
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stop = jiffies + timeout;
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if (chip->flags & TPM_CHIP_FLAG_IRQ) {
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again:
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timeout = stop - jiffies;
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if ((long)timeout <= 0)
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return -ETIME;
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rc = wait_event_interruptible_timeout(*queue,
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wait_for_tpm_stat_cond(chip, mask, check_cancel,
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&canceled),
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timeout);
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if (rc > 0) {
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if (canceled)
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return -ECANCELED;
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return 0;
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}
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if (rc == -ERESTARTSYS && freezing(current)) {
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clear_thread_flag(TIF_SIGPENDING);
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goto again;
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}
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} else {
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do {
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tpm_msleep(TPM_TIMEOUT);
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status = chip->ops->status(chip);
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if ((status & mask) == mask)
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return 0;
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} while (time_before(jiffies, stop));
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}
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return -ETIME;
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}
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static u8 vtpm_status(struct tpm_chip *chip)
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{
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struct tpm_private *priv = dev_get_drvdata(&chip->dev);
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switch (priv->shr->state) {
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case VTPM_STATE_IDLE:
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return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
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case VTPM_STATE_FINISH:
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return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
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case VTPM_STATE_SUBMIT:
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case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
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return VTPM_STATUS_RUNNING;
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default:
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return 0;
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}
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}
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static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
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{
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return status & VTPM_STATUS_CANCELED;
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}
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static void vtpm_cancel(struct tpm_chip *chip)
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{
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struct tpm_private *priv = dev_get_drvdata(&chip->dev);
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priv->shr->state = VTPM_STATE_CANCEL;
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wmb();
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notify_remote_via_evtchn(priv->evtchn);
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}
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static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
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{
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return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
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}
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static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
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{
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struct tpm_private *priv = dev_get_drvdata(&chip->dev);
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struct vtpm_shared_page *shr = priv->shr;
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unsigned int offset = shr_data_offset(shr);
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u32 ordinal;
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unsigned long duration;
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if (offset > PAGE_SIZE)
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return -EINVAL;
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if (offset + count > PAGE_SIZE)
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return -EINVAL;
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/* Wait for completion of any existing command or cancellation */
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if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
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&priv->read_queue, true) < 0) {
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vtpm_cancel(chip);
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return -ETIME;
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}
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memcpy(offset + (u8 *)shr, buf, count);
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shr->length = count;
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barrier();
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shr->state = VTPM_STATE_SUBMIT;
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wmb();
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notify_remote_via_evtchn(priv->evtchn);
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ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
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duration = tpm_calc_ordinal_duration(chip, ordinal);
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if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
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&priv->read_queue, true) < 0) {
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/* got a signal or timeout, try to cancel */
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vtpm_cancel(chip);
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return -ETIME;
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}
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return count;
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}
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static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
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{
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struct tpm_private *priv = dev_get_drvdata(&chip->dev);
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struct vtpm_shared_page *shr = priv->shr;
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unsigned int offset = shr_data_offset(shr);
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size_t length = shr->length;
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if (shr->state == VTPM_STATE_IDLE)
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return -ECANCELED;
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/* In theory the wait at the end of _send makes this one unnecessary */
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if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
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&priv->read_queue, true) < 0) {
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vtpm_cancel(chip);
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return -ETIME;
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}
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if (offset > PAGE_SIZE)
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return -EIO;
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if (offset + length > PAGE_SIZE)
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length = PAGE_SIZE - offset;
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if (length > count)
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length = count;
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memcpy(buf, offset + (u8 *)shr, length);
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return length;
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}
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static const struct tpm_class_ops tpm_vtpm = {
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.status = vtpm_status,
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.recv = vtpm_recv,
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.send = vtpm_send,
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.cancel = vtpm_cancel,
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.req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
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.req_complete_val = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
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.req_canceled = vtpm_req_canceled,
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};
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static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
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{
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struct tpm_private *priv = dev_id;
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switch (priv->shr->state) {
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case VTPM_STATE_IDLE:
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case VTPM_STATE_FINISH:
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wake_up_interruptible(&priv->read_queue);
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break;
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case VTPM_STATE_SUBMIT:
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case VTPM_STATE_CANCEL:
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default:
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break;
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}
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return IRQ_HANDLED;
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}
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static int setup_chip(struct device *dev, struct tpm_private *priv)
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{
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struct tpm_chip *chip;
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chip = tpmm_chip_alloc(dev, &tpm_vtpm);
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if (IS_ERR(chip))
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return PTR_ERR(chip);
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init_waitqueue_head(&priv->read_queue);
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priv->chip = chip;
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dev_set_drvdata(&chip->dev, priv);
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return 0;
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}
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/* caller must clean up in case of errors */
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static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
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{
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struct xenbus_transaction xbt;
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const char *message = NULL;
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int rv;
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grant_ref_t gref;
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priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
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if (!priv->shr) {
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xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
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return -ENOMEM;
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}
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rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
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if (rv < 0)
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return rv;
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priv->ring_ref = gref;
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rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
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if (rv)
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return rv;
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rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
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"tpmif", priv);
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if (rv <= 0) {
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xenbus_dev_fatal(dev, rv, "allocating TPM irq");
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return rv;
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}
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priv->irq = rv;
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again:
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rv = xenbus_transaction_start(&xbt);
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if (rv) {
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xenbus_dev_fatal(dev, rv, "starting transaction");
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return rv;
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}
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rv = xenbus_printf(xbt, dev->nodename,
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"ring-ref", "%u", priv->ring_ref);
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if (rv) {
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message = "writing ring-ref";
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goto abort_transaction;
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}
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rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
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priv->evtchn);
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if (rv) {
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message = "writing event-channel";
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goto abort_transaction;
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}
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rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
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if (rv) {
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message = "writing feature-protocol-v2";
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goto abort_transaction;
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}
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rv = xenbus_transaction_end(xbt, 0);
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if (rv == -EAGAIN)
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goto again;
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if (rv) {
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xenbus_dev_fatal(dev, rv, "completing transaction");
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return rv;
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}
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xenbus_switch_state(dev, XenbusStateInitialised);
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return 0;
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abort_transaction:
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xenbus_transaction_end(xbt, 1);
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if (message)
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xenbus_dev_error(dev, rv, "%s", message);
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return rv;
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}
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static void ring_free(struct tpm_private *priv)
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{
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if (!priv)
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return;
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if (priv->ring_ref)
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gnttab_end_foreign_access(priv->ring_ref, 0,
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(unsigned long)priv->shr);
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else
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free_page((unsigned long)priv->shr);
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if (priv->irq)
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unbind_from_irqhandler(priv->irq, priv);
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kfree(priv);
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}
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static int tpmfront_probe(struct xenbus_device *dev,
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const struct xenbus_device_id *id)
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{
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struct tpm_private *priv;
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int rv;
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priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (!priv) {
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xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
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return -ENOMEM;
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}
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rv = setup_chip(&dev->dev, priv);
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if (rv) {
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kfree(priv);
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return rv;
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}
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rv = setup_ring(dev, priv);
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if (rv) {
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ring_free(priv);
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return rv;
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}
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tpm_get_timeouts(priv->chip);
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return tpm_chip_register(priv->chip);
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}
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static int tpmfront_remove(struct xenbus_device *dev)
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{
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struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
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struct tpm_private *priv = dev_get_drvdata(&chip->dev);
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tpm_chip_unregister(chip);
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ring_free(priv);
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dev_set_drvdata(&chip->dev, NULL);
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return 0;
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}
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static int tpmfront_resume(struct xenbus_device *dev)
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{
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/* A suspend/resume/migrate will interrupt a vTPM anyway */
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tpmfront_remove(dev);
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return tpmfront_probe(dev, NULL);
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}
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static void backend_changed(struct xenbus_device *dev,
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enum xenbus_state backend_state)
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{
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switch (backend_state) {
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case XenbusStateInitialised:
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case XenbusStateConnected:
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if (dev->state == XenbusStateConnected)
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break;
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if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
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0)) {
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xenbus_dev_fatal(dev, -EINVAL,
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"vTPM protocol 2 required");
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return;
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}
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xenbus_switch_state(dev, XenbusStateConnected);
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break;
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case XenbusStateClosing:
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case XenbusStateClosed:
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device_unregister(&dev->dev);
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xenbus_frontend_closed(dev);
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break;
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default:
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break;
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}
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}
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static const struct xenbus_device_id tpmfront_ids[] = {
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{ "vtpm" },
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{ "" }
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};
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MODULE_ALIAS("xen:vtpm");
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static struct xenbus_driver tpmfront_driver = {
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.ids = tpmfront_ids,
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.probe = tpmfront_probe,
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.remove = tpmfront_remove,
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.resume = tpmfront_resume,
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.otherend_changed = backend_changed,
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};
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static int __init xen_tpmfront_init(void)
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{
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if (!xen_domain())
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return -ENODEV;
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if (!xen_has_pv_devices())
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return -ENODEV;
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return xenbus_register_frontend(&tpmfront_driver);
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}
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module_init(xen_tpmfront_init);
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static void __exit xen_tpmfront_exit(void)
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{
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xenbus_unregister_driver(&tpmfront_driver);
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}
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module_exit(xen_tpmfront_exit);
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MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
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MODULE_DESCRIPTION("Xen vTPM Driver");
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MODULE_LICENSE("GPL");
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