/* SPDX-License-Identifier: GPL-2.0 */ /* * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */ #ifndef _VDSO_GETRANDOM_H #define _VDSO_GETRANDOM_H #include <linux/types.h> #define CHACHA_KEY_SIZE 32 #define CHACHA_BLOCK_SIZE 64 /** * struct vgetrandom_state - State used by vDSO getrandom(). * * @batch: One and a half ChaCha20 blocks of buffered RNG output. * * @key: Key to be used for generating next batch. * * @batch_key: Union of the prior two members, which is exactly two full * ChaCha20 blocks in size, so that @batch and @key can be filled * together. * * @generation: Snapshot of @rng_info->generation in the vDSO data page at * the time @key was generated. * * @pos: Offset into @batch of the next available random byte. * * @in_use: Reentrancy guard for reusing a state within the same thread * due to signal handlers. */ struct vgetrandom_state { union { struct { u8 batch[CHACHA_BLOCK_SIZE * 3 / 2]; u32 key[CHACHA_KEY_SIZE / sizeof(u32)]; }; u8 batch_key[CHACHA_BLOCK_SIZE * 2]; }; u64 generation; u8 pos; bool in_use; }; #endif /* _VDSO_GETRANDOM_H */