[PATCH] tpm: Move Linux RNG connection to hwrng
PrasannaKumar Muralidharan
prasannatsmkumar at gmail.com
Wed Oct 25 14:45:09 UTC 2017
Hi Jason,
Nice to see this patch. Some minor comments below.
On 25 October 2017 at 00:12, Jason Gunthorpe
<jgunthorpe at obsidianresearch.com> wrote:
> 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: PrasannaKumar Muralidharan <prasannatsmkumar at gmail.com>
> Signed-off-by: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
> Reviewed-by: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
> ---
> drivers/char/hw_random/Kconfig | 13 -----------
> drivers/char/hw_random/Makefile | 1 -
> drivers/char/hw_random/tpm-rng.c | 50 ----------------------------------------
> drivers/char/tpm/Kconfig | 13 +++++++++++
> drivers/char/tpm/tpm-chip.c | 41 ++++++++++++++++++++++++++++----
> drivers/char/tpm/tpm-interface.c | 37 ++++++++++++++++-------------
> drivers/char/tpm/tpm.h | 5 ++++
> 7 files changed, 76 insertions(+), 84 deletions(-)
> delete mode 100644 drivers/char/hw_random/tpm-rng.c
>
> All,
>
> It is such a good idea, I took PrasannaKumar's patch, reviewed and
> revised it to the level it could be merged.
Thank you for this.
> This is compile tested only.
>
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index 95a031e9eced07..a20fed182cbcce 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -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
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index 39a67defac67cb..91cb8e8213e7c1 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -26,7 +26,6 @@ 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
> diff --git a/drivers/char/hw_random/tpm-rng.c b/drivers/char/hw_random/tpm-rng.c
> deleted file mode 100644
> index d6d448266f0752..00000000000000
> --- a/drivers/char/hw_random/tpm-rng.c
> +++ /dev/null
> @@ -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(TPM_ANY_NUM, 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 at linux.vnet.ibm.com>");
> -MODULE_DESCRIPTION("RNG driver for TPM devices");
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index a30352202f1fdc..a95725fa77789e 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -26,6 +26,19 @@ menuconfig TCG_TPM
>
> if TCG_TPM
>
> +config HW_RANDOM_TPM
> + tristate "TPM HW Random Number Generator support"
> + depends on TCG_TPM && HW_RANDOM
> + 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 TCG_TIS_CORE
> tristate
> ---help---
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 0eca20c5a80cf2..f3571406fb2995 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -26,6 +26,7 @@
> #include <linux/spinlock.h>
> #include <linux/freezer.h>
> #include <linux/major.h>
> +#include <linux/hw_random.h>
> #include "tpm.h"
> #include "tpm_eventlog.h"
>
> @@ -387,6 +388,26 @@ 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, tpm_hwrng);
> +
> + return tpm_get_random_dev(chip, data, max);
> +}
> +
> +static int tpm_add_hwrng(struct tpm_chip *chip)
> +{
> + if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
> + return 0;
Can #ifndef CONFIG_HW_RANDOM_TPM be used instead? That way an if
condition can be avoided.
> +
> + snprintf(chip->tpm_hwrng_name, sizeof(chip->tpm_hwrng_name),
> + "tpm-rng-%d", chip->dev_num);
> + chip->tpm_hwrng.name = chip->tpm_hwrng_name;
> + chip->tpm_hwrng.read = tpm_hwrng_read;
> + return hwrng_register(&chip->tpm_hwrng);
> +}
> +
> /*
> * tpm_chip_register() - create a character device for the TPM chip
> * @chip: TPM chip to use.
> @@ -419,11 +440,13 @@ 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) {
> @@ -432,6 +455,14 @@ int tpm_chip_register(struct tpm_chip *chip)
> }
>
> return 0;
> +
> +out_hwrng:
> + if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
> + hwrng_unregister(&chip->tpm_hwrng);
> +out_ppi:
> + tpm_bios_log_teardown(chip);
> +
> + return rc;
> }
> EXPORT_SYMBOL_GPL(tpm_chip_register);
>
> @@ -451,6 +482,8 @@ 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->tpm_hwrng);
> tpm_bios_log_teardown(chip);
> if (chip->flags & TPM_CHIP_FLAG_TPM2)
> cdev_device_del(&chip->cdevs, &chip->devs);
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 1d6729be4cd637..310de288549818 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -1194,9 +1194,8 @@ static const struct tpm_input_header tpm_getrandom_header = {
> *
> * Returns < 0 on error and the number of bytes read on success
> */
> -int tpm_get_random(u32 chip_num, u8 *out, size_t max)
> +int tpm_get_random_dev(struct tpm_chip *chip, u8 *out, size_t max)
> {
> - struct tpm_chip *chip;
> struct tpm_cmd_t tpm_cmd;
> u32 recd, num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA), rlength;
> int err, total = 0, retries = 5;
> @@ -1205,15 +1204,8 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
> if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
> return -EINVAL;
>
> - chip = tpm_chip_find_get(chip_num);
> - if (chip == NULL)
> - return -ENODEV;
> -
> - if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> - err = tpm2_get_random(chip, out, max);
> - tpm_put_ops(chip);
> - return err;
> - }
> + if (chip->flags & TPM_CHIP_FLAG_TPM2)
> + return tpm2_get_random(chip, out, max);
>
> do {
> tpm_cmd.header.in = tpm_getrandom_header;
> @@ -1231,10 +1223,9 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
>
> rlength = be32_to_cpu(tpm_cmd.header.out.length);
> if (rlength < offsetof(struct tpm_getrandom_out, rng_data) +
> - recd) {
> - total = -EFAULT;
> - break;
> - }
> + recd)
> + return -EFAULT;
> +
> memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
>
> dest += recd;
> @@ -1242,9 +1233,23 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
> num_bytes -= recd;
> } while (retries-- && total < max);
>
> - tpm_put_ops(chip);
> return total ? total : -EIO;
> }
> +
> +int tpm_get_random(u32 chip_num, u8 *out, size_t max)
> +{
> + int rc;
> + struct tpm_chip *chip;
> +
> + chip = tpm_chip_find_get(chip_num);
> + if (chip == NULL)
> + return -ENODEV;
> +
> + rc = tpm_get_random_dev(chip, out, max);
> +
> + tpm_put_ops(chip);
> + return rc;
> +}
> EXPORT_SYMBOL_GPL(tpm_get_random);
>
> /**
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 2d5466a72e40f8..0e41e044d81be2 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -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>
> @@ -210,6 +211,9 @@ struct tpm_chip {
> int dev_num; /* /dev/tpm# */
> unsigned long is_open; /* only one allowed */
>
> + char tpm_hwrng_name[64];
> + struct hwrng tpm_hwrng;
> +
Can this also be put inside the #ifdef?
> struct mutex tpm_mutex; /* tpm is processing */
>
> unsigned long timeout_a; /* jiffies */
> @@ -548,6 +552,7 @@ void tpm_chip_unregister(struct tpm_chip *chip);
> void tpm_sysfs_add_device(struct tpm_chip *chip);
>
> int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
> +int tpm_get_random_dev(struct tpm_chip *chip, u8 *out, size_t max);
>
> #ifdef CONFIG_ACPI
> extern void tpm_add_ppi(struct tpm_chip *chip);
> --
> 2.7.4
>
Regards,
PrasannaKumar
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