1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 */
5 #ifndef __ASM_VDSO_GETRANDOM_H
6 #define __ASM_VDSO_GETRANDOM_H
7
8 #ifndef __ASSEMBLY__
9
10 #include <asm/unistd.h>
11 #include <asm/vvar.h>
12
13 /**
14 * getrandom_syscall - Invoke the getrandom() syscall.
15 * @buffer: Destination buffer to fill with random bytes.
16 * @len: Size of @buffer in bytes.
17 * @flags: Zero or more GRND_* flags.
18 * Returns: The number of random bytes written to @buffer, or a negative value indicating an error.
19 */
20 static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
21 {
22 long ret;
23
24 asm ("syscall" : "=a" (ret) :
25 "" (__NR_getrandom), "D" (buffer), "S" (len), "d" (flags) :
26 "rcx", "r11", "memory");
27
28 return ret;
29 }
30
31 #define __vdso_rng_data (VVAR(_vdso_rng_data))
32
33 static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
34 {
35 if (IS_ENABLED(CONFIG_TIME_NS) && __vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
36 return (void *)&__vdso_rng_data + ((void *)&__timens_vdso_data - (void *)&__vdso_data);
37 return &__vdso_rng_data;
38 }
39
40 /**
41 * __arch_chacha20_blocks_nostack - Generate ChaCha20 stream without using the stack.
42 * @dst_bytes: Destination buffer to hold @nblocks * 64 bytes of output.
43 * @key: 32-byte input key.
44 * @counter: 8-byte counter, read on input and updated on return.
45 * @nblocks: Number of blocks to generate.
46 *
47 * Generates a given positive number of blocks of ChaCha20 output with nonce=0, and does not write
48 * to any stack or memory outside of the parameters passed to it, in order to mitigate stack data
49 * leaking into forked child processes.
50 */
51 extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks);
52
53 #endif /* !__ASSEMBLY__ */
54
55 #endif /* __ASM_VDSO_GETRANDOM_H */
56
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.