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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#ifndef __ASM_VDSO_GETRANDOM_H
#define __ASM_VDSO_GETRANDOM_H
#ifndef __ASSEMBLY__
#include <asm/unistd.h>
#include <asm/vvar.h>
/**
* getrandom_syscall - Invoke the getrandom() syscall.
* @buffer: Destination buffer to fill with random bytes.
* @len: Size of @buffer in bytes.
* @flags: Zero or more GRND_* flags.
* Returns: The number of random bytes written to @buffer, or a negative value indicating an error.
*/
static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
{
long ret;
asm ("syscall" : "=a" (ret) :
"0" (__NR_getrandom), "D" (buffer), "S" (len), "d" (flags) :
"rcx", "r11", "memory");
return ret;
}
#define __vdso_rng_data (VVAR(_vdso_rng_data))
static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
{
if (IS_ENABLED(CONFIG_TIME_NS) && __vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
return (void *)&__vdso_rng_data + ((void *)&__timens_vdso_data - (void *)&__vdso_data);
return &__vdso_rng_data;
}
/**
* __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);
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETRANDOM_H */
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