linux/drivers/char/tpm/tpm-interface.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004 IBM Corporation
 * Copyright (C) 2014 Intel Corporation
 *
 * Authors:
 * Leendert van Doorn <[email protected]>
 * Dave Safford <[email protected]>
 * Reiner Sailer <[email protected]>
 * Kylene Hall <[email protected]>
 *
 * Maintained by: <[email protected]>
 *
 * Device driver for TCG/TCPA TPM (trusted platform module).
 * Specifications at www.trustedcomputinggroup.org
 *
 * Note, the TPM chip is not interrupt driven (only polling)
 * and can have very long timeouts (minutes!). Hence the unusual
 * calls to msleep.
 */

#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/suspend.h>
#include <linux/freezer.h>
#include <linux/tpm_eventlog.h>

#include "tpm.h"

/*
 * Bug workaround - some TPM's don't flush the most
 * recently changed pcr on suspend, so force the flush
 * with an extend to the selected _unused_ non-volatile pcr.
 */
static u32 tpm_suspend_pcr;
module_param_named(suspend_pcr, tpm_suspend_pcr, uint, 0644);
MODULE_PARM_DESC(…) …;

/**
 * tpm_calc_ordinal_duration() - calculate the maximum command duration
 * @chip:    TPM chip to use.
 * @ordinal: TPM command ordinal.
 *
 * The function returns the maximum amount of time the chip could take
 * to return the result for a particular ordinal in jiffies.
 *
 * Return: A maximal duration time for an ordinal in jiffies.
 */
unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
{ … }
EXPORT_SYMBOL_GPL(…);

static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
{ … }

/**
 * tpm_transmit - Internal kernel interface to transmit TPM commands.
 * @chip:	a TPM chip to use
 * @buf:	a TPM command buffer
 * @bufsiz:	length of the TPM command buffer
 *
 * A wrapper around tpm_try_transmit() that handles TPM2_RC_RETRY returns from
 * the TPM and retransmits the command after a delay up to a maximum wait of
 * TPM2_DURATION_LONG.
 *
 * Note that TPM 1.x never returns TPM2_RC_RETRY so the retry logic is TPM 2.0
 * only.
 *
 * Return:
 * * The response length	- OK
 * * -errno			- A system error
 */
ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz)
{ … }

/**
 * tpm_transmit_cmd - send a tpm command to the device
 * @chip:			a TPM chip to use
 * @buf:			a TPM command buffer
 * @min_rsp_body_length:	minimum expected length of response body
 * @desc:			command description used in the error message
 *
 * Return:
 * * 0		- OK
 * * -errno	- A system error
 * * TPM_RC	- A TPM error
 */
ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
			 size_t min_rsp_body_length, const char *desc)
{ … }
EXPORT_SYMBOL_GPL(…);

int tpm_get_timeouts(struct tpm_chip *chip)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * tpm_is_tpm2 - do we a have a TPM2 chip?
 * @chip:	a &struct tpm_chip instance, %NULL for the default chip
 *
 * Return:
 * 1 if we have a TPM2 chip.
 * 0 if we don't have a TPM2 chip.
 * A negative number for system errors (errno).
 */
int tpm_is_tpm2(struct tpm_chip *chip)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * tpm_pcr_read - read a PCR value from SHA1 bank
 * @chip:	a &struct tpm_chip instance, %NULL for the default chip
 * @pcr_idx:	the PCR to be retrieved
 * @digest:	the PCR bank and buffer current PCR value is written to
 *
 * Return: same as with tpm_transmit_cmd()
 */
int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
		 struct tpm_digest *digest)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * tpm_pcr_extend - extend a PCR value in SHA1 bank.
 * @chip:	a &struct tpm_chip instance, %NULL for the default chip
 * @pcr_idx:	the PCR to be retrieved
 * @digests:	array of tpm_digest structures used to extend PCRs
 *
 * Note: callers must pass a digest for every allocated PCR bank, in the same
 * order of the banks in chip->allocated_banks.
 *
 * Return: same as with tpm_transmit_cmd()
 */
int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
		   struct tpm_digest *digests)
{ … }
EXPORT_SYMBOL_GPL(…);

int tpm_auto_startup(struct tpm_chip *chip)
{ … }

/*
 * We are about to suspend. Save the TPM state
 * so that it can be restored.
 */
int tpm_pm_suspend(struct device *dev)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Resume from a power safe. The BIOS already restored
 * the TPM state.
 */
int tpm_pm_resume(struct device *dev)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * tpm_get_random() - get random bytes from the TPM's RNG
 * @chip:	a &struct tpm_chip instance, %NULL for the default chip
 * @out:	destination buffer for the random bytes
 * @max:	the max number of bytes to write to @out
 *
 * Return: number of random bytes read or a negative error value.
 */
int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
{ … }
EXPORT_SYMBOL_GPL(…);

static int __init tpm_init(void)
{ … }

static void __exit tpm_exit(void)
{ … }

subsys_initcall(tpm_init);
module_exit(tpm_exit);

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_VERSION(…) …;
MODULE_LICENSE(…) …;