/* SPDX-License-Identifier: GPL-2.0 */ /* * Copyright (C) 2022-2024 Jason A. Donenfeld <[email protected]>. All Rights Reserved. */ #ifndef _VDSO_GETRANDOM_H #define _VDSO_GETRANDOM_H #include <linux/types.h> #define CHACHA_KEY_SIZE … #define CHACHA_BLOCK_SIZE … /** * 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 { … }; /** * __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 */
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