efi_rng.c
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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2019, Linaro Limited
*/
#include <common.h>
#include <dm.h>
#include <efi_loader.h>
#include <efi_rng.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);
}
const struct efi_rng_protocol efi_rng_protocol = {
.get_info = rng_getinfo,
.get_rng = getrng,
};