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108 lines
2.9 KiB
108 lines
2.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2016 Linaro Ltd; <[email protected]> |
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*/ |
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#include <linux/efi.h> |
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#include <asm/efi.h> |
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#include "efistub.h" |
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typedef union efi_rng_protocol efi_rng_protocol_t; |
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union efi_rng_protocol { |
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struct { |
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efi_status_t (__efiapi *get_info)(efi_rng_protocol_t *, |
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unsigned long *, |
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efi_guid_t *); |
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efi_status_t (__efiapi *get_rng)(efi_rng_protocol_t *, |
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efi_guid_t *, unsigned long, |
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u8 *out); |
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}; |
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struct { |
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u32 get_info; |
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u32 get_rng; |
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} mixed_mode; |
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}; |
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/** |
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* efi_get_random_bytes() - fill a buffer with random bytes |
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* @size: size of the buffer |
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* @out: caller allocated buffer to receive the random bytes |
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* |
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* The call will fail if either the firmware does not implement the |
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* EFI_RNG_PROTOCOL or there are not enough random bytes available to fill |
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* the buffer. |
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* |
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* Return: status code |
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*/ |
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efi_status_t efi_get_random_bytes(unsigned long size, u8 *out) |
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{ |
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efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; |
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efi_status_t status; |
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efi_rng_protocol_t *rng = NULL; |
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status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); |
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if (status != EFI_SUCCESS) |
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return status; |
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return efi_call_proto(rng, get_rng, NULL, size, out); |
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} |
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/** |
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* efi_random_get_seed() - provide random seed as configuration table |
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* |
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* The EFI_RNG_PROTOCOL is used to read random bytes. These random bytes are |
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* saved as a configuration table which can be used as entropy by the kernel |
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* for the initialization of its pseudo random number generator. |
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* |
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* If the EFI_RNG_PROTOCOL is not available or there are not enough random bytes |
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* available, the configuration table will not be installed and an error code |
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* will be returned. |
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* |
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* Return: status code |
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*/ |
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efi_status_t efi_random_get_seed(void) |
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{ |
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efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; |
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efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; |
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efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; |
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efi_rng_protocol_t *rng = NULL; |
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struct linux_efi_random_seed *seed = NULL; |
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efi_status_t status; |
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status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); |
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if (status != EFI_SUCCESS) |
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return status; |
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status = efi_bs_call(allocate_pool, EFI_RUNTIME_SERVICES_DATA, |
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sizeof(*seed) + EFI_RANDOM_SEED_SIZE, |
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(void **)&seed); |
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if (status != EFI_SUCCESS) |
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return status; |
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status = efi_call_proto(rng, get_rng, &rng_algo_raw, |
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EFI_RANDOM_SEED_SIZE, seed->bits); |
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if (status == EFI_UNSUPPORTED) |
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/* |
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* Use whatever algorithm we have available if the raw algorithm |
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* is not implemented. |
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*/ |
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status = efi_call_proto(rng, get_rng, NULL, |
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EFI_RANDOM_SEED_SIZE, seed->bits); |
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if (status != EFI_SUCCESS) |
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goto err_freepool; |
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seed->size = EFI_RANDOM_SEED_SIZE; |
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status = efi_bs_call(install_configuration_table, &rng_table_guid, seed); |
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if (status != EFI_SUCCESS) |
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goto err_freepool; |
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return EFI_SUCCESS; |
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err_freepool: |
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efi_bs_call(free_pool, seed); |
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return status; |
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}
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