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tpm: Move Linux RNG connection to hwrng

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The tpm-rng.c approach is completely inconsistent with how the kernel
handles hotplug. Instead manage a hwrng device for each TPM. This will
cause the kernel to read entropy from the TPM when it is plugged in, and
allow access to the TPM rng via /dev/hwrng.

Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca>
Tested-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Jason Gunthorpe 2017-11-17 15:24:03 +02:00 committed by Jarkko Sakkinen
parent aad887f664
commit 6e592a065d
6 changed files with 52 additions and 69 deletions
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13
drivers/char/hw_random/Kconfig
View File

@ -306,19 +306,6 @@ config HW_RANDOM_POWERNV
If unsure, say Y.
config HW_RANDOM_TPM
tristate "TPM HW Random Number Generator support"
depends on TCG_TPM
default HW_RANDOM
---help---
This driver provides kernel-side support for the Random Number
Generator in the Trusted Platform Module
To compile this driver as a module, choose M here: the
module will be called tpm-rng.
If unsure, say Y.
config HW_RANDOM_HISI
tristate "Hisilicon Random Number Generator support"
depends on HW_RANDOM && ARCH_HISI

1
drivers/char/hw_random/Makefile
View File

@ -27,7 +27,6 @@ obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
obj-$(CONFIG_HW_RANDOM_HISI) += hisi-rng.o
obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o

50
drivers/char/hw_random/tpm-rng.c
View File

@ -1,50 +0,0 @@
/*
* Copyright (C) 2012 Kent Yoder IBM Corporation
*
* HWRNG interfaces to pull RNG data from a TPM
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/hw_random.h>
#include <linux/tpm.h>
#define MODULE_NAME "tpm-rng"
static int tpm_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
return tpm_get_random(NULL, data, max);
}
static struct hwrng tpm_rng = {
.name = MODULE_NAME,
.read = tpm_rng_read,
};
static int __init rng_init(void)
{
return hwrng_register(&tpm_rng);
}
module_init(rng_init);
static void __exit rng_exit(void)
{
hwrng_unregister(&tpm_rng);
}
module_exit(rng_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Kent Yoder <key@linux.vnet.ibm.com>");
MODULE_DESCRIPTION("RNG driver for TPM devices");

11
drivers/char/tpm/Kconfig
View File

@ -26,6 +26,17 @@ menuconfig TCG_TPM
if TCG_TPM
config HW_RANDOM_TPM
bool "TPM HW Random Number Generator support"
depends on TCG_TPM && HW_RANDOM && !(TCG_TPM=y && HW_RANDOM=m)
default y
---help---
This setting exposes the TPM's Random Number Generator as a hwrng
device. This allows the kernel to collect randomness from the TPM at
boot, and provides the TPM randomines in /dev/hwrng.
If unsure, say Y.
config TCG_TIS_CORE
tristate
---help---

42
drivers/char/tpm/tpm-chip.c
View File

@ -27,7 +27,7 @@
#include <linux/freezer.h>
#include <linux/major.h>
#include <linux/tpm_eventlog.h>
#include <linux/hw_random.h>
#include "tpm.h"
DEFINE_IDR(dev_nums_idr);
@ -392,6 +392,26 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
return 0;
}
static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng);
return tpm_get_random(chip, data, max);
}
static int tpm_add_hwrng(struct tpm_chip *chip)
{
if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
return 0;
snprintf(chip->hwrng_name, sizeof(chip->hwrng_name),
"tpm-rng-%d", chip->dev_num);
chip->hwrng.name = chip->hwrng_name;
chip->hwrng.read = tpm_hwrng_read;
return hwrng_register(&chip->hwrng);
}
/*
* tpm_chip_register() - create a character device for the TPM chip
* @chip: TPM chip to use.
@ -424,11 +444,13 @@ int tpm_chip_register(struct tpm_chip *chip)
tpm_add_ppi(chip);
rc = tpm_add_hwrng(chip);
if (rc)
goto out_ppi;
rc = tpm_add_char_device(chip);
if (rc) {
tpm_bios_log_teardown(chip);
return rc;
}
if (rc)
goto out_hwrng;
rc = tpm_add_legacy_sysfs(chip);
if (rc) {
@ -437,6 +459,14 @@ int tpm_chip_register(struct tpm_chip *chip)
}
return 0;
out_hwrng:
if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
hwrng_unregister(&chip->hwrng);
out_ppi:
tpm_bios_log_teardown(chip);
return rc;
}
EXPORT_SYMBOL_GPL(tpm_chip_register);
@ -456,6 +486,8 @@ EXPORT_SYMBOL_GPL(tpm_chip_register);
void tpm_chip_unregister(struct tpm_chip *chip)
{
tpm_del_legacy_sysfs(chip);
if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
hwrng_unregister(&chip->hwrng);
tpm_bios_log_teardown(chip);
if (chip->flags & TPM_CHIP_FLAG_TPM2)
cdev_device_del(&chip->cdevs, &chip->devs);

4
drivers/char/tpm/tpm.h
View File

@ -26,6 +26,7 @@
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/hw_random.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/platform_device.h>
@ -211,6 +212,9 @@ struct tpm_chip {
int dev_num; /* /dev/tpm# */
unsigned long is_open; /* only one allowed */
char hwrng_name[64];
struct hwrng hwrng;
struct mutex tpm_mutex; /* tpm is processing */
unsigned long timeout_a; /* jiffies */