14febfb8dSArd Biesheuvel // SPDX-License-Identifier: GPL-2.0 2e4fbf476SArd Biesheuvel /* 3e4fbf476SArd Biesheuvel * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org> 4e4fbf476SArd Biesheuvel */ 5e4fbf476SArd Biesheuvel 6e4fbf476SArd Biesheuvel #include <linux/efi.h> 7e4fbf476SArd Biesheuvel #include <asm/efi.h> 8e4fbf476SArd Biesheuvel 9e4fbf476SArd Biesheuvel #include "efistub.h" 10e4fbf476SArd Biesheuvel 111786e830SArd Biesheuvel typedef union efi_rng_protocol efi_rng_protocol_t; 1241e8a7c2SDominik Brodowski 131786e830SArd Biesheuvel union efi_rng_protocol { 141786e830SArd Biesheuvel struct { 158f24f8c2SArd Biesheuvel efi_status_t (__efiapi *get_info)(efi_rng_protocol_t *, 168f24f8c2SArd Biesheuvel unsigned long *, 178f24f8c2SArd Biesheuvel efi_guid_t *); 188f24f8c2SArd Biesheuvel efi_status_t (__efiapi *get_rng)(efi_rng_protocol_t *, 198f24f8c2SArd Biesheuvel efi_guid_t *, unsigned long, 208f24f8c2SArd Biesheuvel u8 *out); 21e4fbf476SArd Biesheuvel }; 221786e830SArd Biesheuvel struct { 231786e830SArd Biesheuvel u32 get_info; 241786e830SArd Biesheuvel u32 get_rng; 251786e830SArd Biesheuvel } mixed_mode; 261786e830SArd Biesheuvel }; 27e4fbf476SArd Biesheuvel 28ba832f68SHeinrich Schuchardt /** 29ba832f68SHeinrich Schuchardt * efi_get_random_bytes() - fill a buffer with random bytes 30ba832f68SHeinrich Schuchardt * @size: size of the buffer 31ba832f68SHeinrich Schuchardt * @out: caller allocated buffer to receive the random bytes 32ba832f68SHeinrich Schuchardt * 33ba832f68SHeinrich Schuchardt * The call will fail if either the firmware does not implement the 34ba832f68SHeinrich Schuchardt * EFI_RNG_PROTOCOL or there are not enough random bytes available to fill 35ba832f68SHeinrich Schuchardt * the buffer. 36ba832f68SHeinrich Schuchardt * 37ba832f68SHeinrich Schuchardt * Return: status code 38ba832f68SHeinrich Schuchardt */ 39cd33a5c1SArd Biesheuvel efi_status_t efi_get_random_bytes(unsigned long size, u8 *out) 40e4fbf476SArd Biesheuvel { 41e4fbf476SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 42e4fbf476SArd Biesheuvel efi_status_t status; 431786e830SArd Biesheuvel efi_rng_protocol_t *rng = NULL; 44e4fbf476SArd Biesheuvel 45966291f6SArd Biesheuvel status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); 46e4fbf476SArd Biesheuvel if (status != EFI_SUCCESS) 47e4fbf476SArd Biesheuvel return status; 48e4fbf476SArd Biesheuvel 4947c0fd39SArd Biesheuvel return efi_call_proto(rng, get_rng, NULL, size, out); 50e4fbf476SArd Biesheuvel } 512ddbfc81SArd Biesheuvel 52ba832f68SHeinrich Schuchardt /** 53ba832f68SHeinrich Schuchardt * efi_random_get_seed() - provide random seed as configuration table 54ba832f68SHeinrich Schuchardt * 55ba832f68SHeinrich Schuchardt * The EFI_RNG_PROTOCOL is used to read random bytes. These random bytes are 56ba832f68SHeinrich Schuchardt * saved as a configuration table which can be used as entropy by the kernel 57ba832f68SHeinrich Schuchardt * for the initialization of its pseudo random number generator. 58ba832f68SHeinrich Schuchardt * 59ba832f68SHeinrich Schuchardt * If the EFI_RNG_PROTOCOL is not available or there are not enough random bytes 60ba832f68SHeinrich Schuchardt * available, the configuration table will not be installed and an error code 61ba832f68SHeinrich Schuchardt * will be returned. 62ba832f68SHeinrich Schuchardt * 63ba832f68SHeinrich Schuchardt * Return: status code 64ba832f68SHeinrich Schuchardt */ 65cd33a5c1SArd Biesheuvel efi_status_t efi_random_get_seed(void) 66568bc4e8SArd Biesheuvel { 67568bc4e8SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 68568bc4e8SArd Biesheuvel efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; 69568bc4e8SArd Biesheuvel efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; 701786e830SArd Biesheuvel efi_rng_protocol_t *rng = NULL; 71818c7ce7SHans de Goede struct linux_efi_random_seed *seed = NULL; 72568bc4e8SArd Biesheuvel efi_status_t status; 73568bc4e8SArd Biesheuvel 74966291f6SArd Biesheuvel status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); 75568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 76568bc4e8SArd Biesheuvel return status; 77568bc4e8SArd Biesheuvel 78966291f6SArd Biesheuvel status = efi_bs_call(allocate_pool, EFI_RUNTIME_SERVICES_DATA, 79c2ceb5fdSArd Biesheuvel sizeof(*seed) + EFI_RANDOM_SEED_SIZE, 80568bc4e8SArd Biesheuvel (void **)&seed); 81568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 82568bc4e8SArd Biesheuvel return status; 83568bc4e8SArd Biesheuvel 8447c0fd39SArd Biesheuvel status = efi_call_proto(rng, get_rng, &rng_algo_raw, 8541e8a7c2SDominik Brodowski EFI_RANDOM_SEED_SIZE, seed->bits); 8641e8a7c2SDominik Brodowski 87568bc4e8SArd Biesheuvel if (status == EFI_UNSUPPORTED) 88568bc4e8SArd Biesheuvel /* 89568bc4e8SArd Biesheuvel * Use whatever algorithm we have available if the raw algorithm 90568bc4e8SArd Biesheuvel * is not implemented. 91568bc4e8SArd Biesheuvel */ 9247c0fd39SArd Biesheuvel status = efi_call_proto(rng, get_rng, NULL, 9341e8a7c2SDominik Brodowski EFI_RANDOM_SEED_SIZE, seed->bits); 94568bc4e8SArd Biesheuvel 95568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 96568bc4e8SArd Biesheuvel goto err_freepool; 97568bc4e8SArd Biesheuvel 98c2ceb5fdSArd Biesheuvel seed->size = EFI_RANDOM_SEED_SIZE; 99966291f6SArd Biesheuvel status = efi_bs_call(install_configuration_table, &rng_table_guid, seed); 100568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 101568bc4e8SArd Biesheuvel goto err_freepool; 102568bc4e8SArd Biesheuvel 103568bc4e8SArd Biesheuvel return EFI_SUCCESS; 104568bc4e8SArd Biesheuvel 105568bc4e8SArd Biesheuvel err_freepool: 106966291f6SArd Biesheuvel efi_bs_call(free_pool, seed); 107568bc4e8SArd Biesheuvel return status; 108568bc4e8SArd Biesheuvel } 109