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