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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (c) 2019, Linaro Limited
- */
- #define LOG_CATEGORY LOGC_EFI
- #include <common.h>
- #include <dm.h>
- #include <efi_loader.h>
- #include <efi_rng.h>
- #include <log.h>
- #include <rng.h>
- DECLARE_GLOBAL_DATA_PTR;
- const efi_guid_t efi_guid_rng_protocol = EFI_RNG_PROTOCOL_GUID;
- /**
- * platform_get_rng_device() - retrieve random number generator
- *
- * This function retrieves the udevice implementing a hardware random
- * number generator.
- *
- * This function may be overridden if special initialization is needed.
- *
- * @dev: udevice
- * Return: status code
- */
- __weak efi_status_t platform_get_rng_device(struct udevice **dev)
- {
- int ret;
- struct udevice *devp;
- ret = uclass_get_device(UCLASS_RNG, 0, &devp);
- if (ret) {
- debug("Unable to get rng device\n");
- return EFI_DEVICE_ERROR;
- }
- *dev = devp;
- return EFI_SUCCESS;
- }
- /**
- * rng_getinfo() - get information about random number generation
- *
- * This function implement the GetInfo() service of the EFI random number
- * generator protocol. See the UEFI spec for details.
- *
- * @this: random number generator protocol instance
- * @rng_algorithm_list_size: number of random number generation algorithms
- * @rng_algorithm_list: descriptions of random number generation
- * algorithms
- * Return: status code
- */
- static efi_status_t EFIAPI rng_getinfo(struct efi_rng_protocol *this,
- efi_uintn_t *rng_algorithm_list_size,
- efi_guid_t *rng_algorithm_list)
- {
- efi_status_t ret = EFI_SUCCESS;
- efi_guid_t rng_algo_guid = EFI_RNG_ALGORITHM_RAW;
- EFI_ENTRY("%p, %p, %p", this, rng_algorithm_list_size,
- rng_algorithm_list);
- if (!this || !rng_algorithm_list_size) {
- ret = EFI_INVALID_PARAMETER;
- goto back;
- }
- if (!rng_algorithm_list ||
- *rng_algorithm_list_size < sizeof(*rng_algorithm_list)) {
- *rng_algorithm_list_size = sizeof(*rng_algorithm_list);
- ret = EFI_BUFFER_TOO_SMALL;
- goto back;
- }
- /*
- * For now, use EFI_RNG_ALGORITHM_RAW as the default
- * algorithm. If a new algorithm gets added in the
- * future through a Kconfig, rng_algo_guid will be set
- * based on that Kconfig option
- */
- *rng_algorithm_list_size = sizeof(*rng_algorithm_list);
- guidcpy(rng_algorithm_list, &rng_algo_guid);
- back:
- return EFI_EXIT(ret);
- }
- /**
- * rng_getrng() - get random value
- *
- * This function implement the GetRng() service of the EFI random number
- * generator protocol. See the UEFI spec for details.
- *
- * @this: random number generator protocol instance
- * @rng_algorithm: random number generation algorithm
- * @rng_value_length: number of random bytes to generate, buffer length
- * @rng_value: buffer to receive random bytes
- * Return: status code
- */
- static efi_status_t EFIAPI getrng(struct efi_rng_protocol *this,
- efi_guid_t *rng_algorithm,
- efi_uintn_t rng_value_length,
- uint8_t *rng_value)
- {
- int ret;
- efi_status_t status = EFI_SUCCESS;
- struct udevice *dev;
- const efi_guid_t rng_raw_guid = EFI_RNG_ALGORITHM_RAW;
- EFI_ENTRY("%p, %p, %zu, %p", this, rng_algorithm, rng_value_length,
- rng_value);
- if (!this || !rng_value || !rng_value_length) {
- status = EFI_INVALID_PARAMETER;
- goto back;
- }
- if (rng_algorithm) {
- EFI_PRINT("RNG algorithm %pUl\n", rng_algorithm);
- if (guidcmp(rng_algorithm, &rng_raw_guid)) {
- status = EFI_UNSUPPORTED;
- goto back;
- }
- }
- ret = platform_get_rng_device(&dev);
- if (ret != EFI_SUCCESS) {
- EFI_PRINT("Rng device not found\n");
- status = EFI_UNSUPPORTED;
- goto back;
- }
- ret = dm_rng_read(dev, rng_value, rng_value_length);
- if (ret < 0) {
- EFI_PRINT("Rng device read failed\n");
- status = EFI_DEVICE_ERROR;
- goto back;
- }
- back:
- return EFI_EXIT(status);
- }
- static const struct efi_rng_protocol efi_rng_protocol = {
- .get_info = rng_getinfo,
- .get_rng = getrng,
- };
- /**
- * efi_rng_register() - register EFI_RNG_PROTOCOL
- *
- * If a RNG device is available, the Random Number Generator Protocol is
- * registered.
- *
- * Return: An error status is only returned if adding the protocol fails.
- */
- efi_status_t efi_rng_register(void)
- {
- efi_status_t ret;
- struct udevice *dev;
- ret = platform_get_rng_device(&dev);
- if (ret != EFI_SUCCESS) {
- log_warning("Missing RNG device for EFI_RNG_PROTOCOL");
- return EFI_SUCCESS;
- }
- ret = efi_add_protocol(efi_root, &efi_guid_rng_protocol,
- (void *)&efi_rng_protocol);
- if (ret != EFI_SUCCESS)
- log_err("Cannot install EFI_RNG_PROTOCOL");
- return ret;
- }
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