/* 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;}; /** * __arch_chacha20_blocks_nostack - Generate ChaCha20 stream without using the stack. * @dst_bytes:	Destination buffer to hold @nblocks * 64 bytes of output. * @key:	32-byte input key. * @counter:	8-byte counter, read on input and updated on return. * @nblocks:	Number of blocks to generate. * * Generates a given positive number of blocks of ChaCha20 output with nonce=0, and does not write * to any stack or memory outside of the parameters passed to it, in order to mitigate stack data * leaking into forked child processes. */extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks); /** * __vdso_getrandom - Architecture-specific vDSO implementation of getrandom() syscall. * @buffer:		Passed to __cvdso_getrandom(). * @len:		Passed to __cvdso_getrandom(). * @flags:		Passed to __cvdso_getrandom(). * @opaque_state:	Passed to __cvdso_getrandom(). * @opaque_len:		Passed to __cvdso_getrandom(); * * This function is implemented by making a single call to to __cvdso_getrandom(), whose * documentation may be consulted for more information. * * Returns:	The return value of __cvdso_getrandom(). */extern ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len); #endif /* _VDSO_GETRANDOM_H */