linux/lib/usercopy.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/fault-inject-usercopy.h>
#include <linux/instrumented.h>
#include <linux/kernel.h>
#include <linux/nospec.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/wordpart.h>

/* out-of-line parts */

#if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)
unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
{ … }
EXPORT_SYMBOL(…);
#endif

#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
{ … }
EXPORT_SYMBOL(…);
#endif

/**
 * check_zeroed_user: check if a userspace buffer only contains zero bytes
 * @from: Source address, in userspace.
 * @size: Size of buffer.
 *
 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
 * userspace addresses (and is more efficient because we don't care where the
 * first non-zero byte is).
 *
 * Returns:
 *  * 0: There were non-zero bytes present in the buffer.
 *  * 1: The buffer was full of zero bytes.
 *  * -EFAULT: access to userspace failed.
 */
int check_zeroed_user(const void __user *from, size_t size)
{ … }
EXPORT_SYMBOL(…);