The TPM device has a builtin random number generator(RNG) functionality. Expose the RNG functions of the TPM device to the driver model so that they can be used by the EFI_RNG_PROTOCOL if the protocol is installed.
Also change the function arguments and return type of the random number functions to comply with the driver model api.
Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org ---
Changes since V4:
* Call the existing tpm_get_random API function from the TPM RNG driver, instead of the tpm{1,2}_get_random API's * Introduce a new Kconfig symbol TPM_RNG and build the corresponding driver if the symbol is enabled * Change the last parameter of the tpm_get_random API to have a data type of size_t instead of u32 to comply with the RNG driver model API
drivers/rng/Kconfig | 7 +++++++ drivers/rng/Makefile | 1 + drivers/rng/tpm_rng.c | 23 +++++++++++++++++++++++ include/tpm-v1.h | 4 ++-- include/tpm-v2.h | 4 ++-- include/tpm_api.h | 2 +- lib/Kconfig | 1 + lib/tpm-v1.c | 16 +++++++++------- lib/tpm-v2.c | 9 +++++---- lib/tpm_api.c | 16 +++++++++++----- 10 files changed, 62 insertions(+), 21 deletions(-) create mode 100644 drivers/rng/tpm_rng.c
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig index b1c5ab93d1..a89fa99ffa 100644 --- a/drivers/rng/Kconfig +++ b/drivers/rng/Kconfig @@ -49,4 +49,11 @@ config RNG_IPROC200 depends on DM_RNG help Enable random number generator for RPI4. + +config TPM_RNG + bool "Enable random number generator on TPM device" + depends on TPM + default y + help + Enable random number generator on TPM devices endif diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile index 39f7ee3f03..a21f3353ea 100644 --- a/drivers/rng/Makefile +++ b/drivers/rng/Makefile @@ -10,3 +10,4 @@ obj-$(CONFIG_RNG_MSM) += msm_rng.o obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o +obj-$(CONFIG_TPM_RNG) += tpm_rng.o diff --git a/drivers/rng/tpm_rng.c b/drivers/rng/tpm_rng.c new file mode 100644 index 0000000000..69b41dbbf5 --- /dev/null +++ b/drivers/rng/tpm_rng.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2022, Linaro Limited + */ + +#include <dm.h> +#include <rng.h> +#include <tpm_api.h> + +static int rng_tpm_random_read(struct udevice *dev, void *data, size_t count) +{ + return tpm_get_random(dev->parent, data, count); +} + +static const struct dm_rng_ops tpm_rng_ops = { + .read = rng_tpm_random_read, +}; + +U_BOOT_DRIVER(tpm_rng) = { + .name = "tpm-rng", + .id = UCLASS_RNG, + .ops = &tpm_rng_ops, +}; diff --git a/include/tpm-v1.h b/include/tpm-v1.h index 33d53fb695..d2ff8b446d 100644 --- a/include/tpm-v1.h +++ b/include/tpm-v1.h @@ -555,9 +555,9 @@ u32 tpm1_find_key_sha1(struct udevice *dev, const u8 auth[20], * @param dev TPM device * @param data output buffer for the random bytes * @param count size of output buffer - * Return: return code of the operation + * Return: 0 if OK, -ve on error */ -u32 tpm1_get_random(struct udevice *dev, void *data, u32 count); +int tpm1_get_random(struct udevice *dev, void *data, size_t count);
/** * tpm_finalise_physical_presence() - Finalise physical presence diff --git a/include/tpm-v2.h b/include/tpm-v2.h index e79c90b939..4fb1e7a948 100644 --- a/include/tpm-v2.h +++ b/include/tpm-v2.h @@ -619,9 +619,9 @@ u32 tpm2_pcr_setauthvalue(struct udevice *dev, const char *pw, * @param data output buffer for the random bytes * @param count size of output buffer * - * Return: return code of the operation + * Return: 0 if OK, -ve on error */ -u32 tpm2_get_random(struct udevice *dev, void *data, u32 count); +int tpm2_get_random(struct udevice *dev, void *data, size_t count);
/** * Lock data in the TPM diff --git a/include/tpm_api.h b/include/tpm_api.h index 4d77a49719..6d9214b335 100644 --- a/include/tpm_api.h +++ b/include/tpm_api.h @@ -276,7 +276,7 @@ u32 tpm_find_key_sha1(struct udevice *dev, const u8 auth[20], * @param count size of output buffer * Return: 0 if OK, -ve on error */ -int tpm_get_random(struct udevice *dev, void *data, u32 count); +int tpm_get_random(struct udevice *dev, void *data, size_t count);
/** * tpm_finalise_physical_presence() - Finalise physical presence diff --git a/lib/Kconfig b/lib/Kconfig index 3c6fa99b1a..f04a9c8c79 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -341,6 +341,7 @@ source lib/crypt/Kconfig config TPM bool "Trusted Platform Module (TPM) Support" depends on DM + imply DM_RNG help This enables support for TPMs which can be used to provide security features for your board. The TPM can be connected via LPC or I2C diff --git a/lib/tpm-v1.c b/lib/tpm-v1.c index 22a769c587..4c6bc31a64 100644 --- a/lib/tpm-v1.c +++ b/lib/tpm-v1.c @@ -9,12 +9,14 @@ #include <common.h> #include <dm.h> #include <log.h> -#include <asm/unaligned.h> -#include <u-boot/sha1.h> +#include <rng.h> #include <tpm-common.h> #include <tpm-v1.h> #include "tpm-utils.h"
+#include <asm/unaligned.h> +#include <u-boot/sha1.h> + #ifdef CONFIG_TPM_AUTH_SESSIONS
#ifndef CONFIG_SHA1 @@ -869,7 +871,7 @@ u32 tpm1_find_key_sha1(struct udevice *dev, const u8 auth[20],
#endif /* CONFIG_TPM_AUTH_SESSIONS */
-u32 tpm1_get_random(struct udevice *dev, void *data, u32 count) +int tpm1_get_random(struct udevice *dev, void *data, size_t count) { const u8 command[14] = { 0x0, 0xc1, /* TPM_TAG */ @@ -892,19 +894,19 @@ u32 tpm1_get_random(struct udevice *dev, void *data, u32 count) if (pack_byte_string(buf, sizeof(buf), "sd", 0, command, sizeof(command), length_offset, this_bytes)) - return TPM_LIB_ERROR; + return -EIO; err = tpm_sendrecv_command(dev, buf, response, &response_length); if (err) return err; if (unpack_byte_string(response, response_length, "d", data_size_offset, &data_size)) - return TPM_LIB_ERROR; + return -EIO; if (data_size > count) - return TPM_LIB_ERROR; + return -EIO; if (unpack_byte_string(response, response_length, "s", data_offset, out, data_size)) - return TPM_LIB_ERROR; + return -EIO;
count -= data_size; out += data_size; diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c index 1bf627853a..d7a23ccf7e 100644 --- a/lib/tpm-v2.c +++ b/lib/tpm-v2.c @@ -6,6 +6,7 @@
#include <common.h> #include <dm.h> +#include <rng.h> #include <tpm-common.h> #include <tpm-v2.h> #include <linux/bitops.h> @@ -562,7 +563,7 @@ u32 tpm2_pcr_setauthvalue(struct udevice *dev, const char *pw, return tpm_sendrecv_command(dev, command_v2, NULL, NULL); }
-u32 tpm2_get_random(struct udevice *dev, void *data, u32 count) +int tpm2_get_random(struct udevice *dev, void *data, size_t count) { const u8 command_v2[10] = { tpm_u16(TPM2_ST_NO_SESSIONS), @@ -585,19 +586,19 @@ u32 tpm2_get_random(struct udevice *dev, void *data, u32 count) if (pack_byte_string(buf, sizeof(buf), "sw", 0, command_v2, sizeof(command_v2), sizeof(command_v2), this_bytes)) - return TPM_LIB_ERROR; + return -EIO; err = tpm_sendrecv_command(dev, buf, response, &response_length); if (err) return err; if (unpack_byte_string(response, response_length, "w", data_size_offset, &data_size)) - return TPM_LIB_ERROR; + return -EIO; if (data_size > this_bytes) return TPM_LIB_ERROR; if (unpack_byte_string(response, response_length, "s", data_offset, out, data_size)) - return TPM_LIB_ERROR; + return -EIO;
count -= data_size; out += data_size; diff --git a/lib/tpm_api.c b/lib/tpm_api.c index da48058abe..8bf60cda3c 100644 --- a/lib/tpm_api.c +++ b/lib/tpm_api.c @@ -6,6 +6,7 @@ #include <common.h> #include <dm.h> #include <log.h> +#include <rng.h> #include <tpm_api.h> #include <tpm-v1.h> #include <tpm-v2.h> @@ -265,12 +266,17 @@ u32 tpm_get_permissions(struct udevice *dev, u32 index, u32 *perm) return -ENOSYS; }
-int tpm_get_random(struct udevice *dev, void *data, u32 count) +int tpm_get_random(struct udevice *dev, void *data, size_t count) { + int ret = -ENOSYS; + if (tpm_is_v1(dev)) - return tpm1_get_random(dev, data, count); + ret = tpm1_get_random(dev, data, count); else if (tpm_is_v2(dev)) - return -ENOSYS; /* not implemented yet */ - else - return -ENOSYS; + ret = tpm2_get_random(dev, data, count); + + if (ret) + log_err("Failed to read random bytes\n"); + + return ret; }