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// SPDX-License-Identifier: GPL-2.0
#include <linux/uaccess.h>
#include <linux/bitops.h>
/* out-of-line parts */
#ifndef INLINE_COPY_FROM_USER
unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
{
unsigned long res = n;
might_fault();
if (likely(access_ok(from, n))) {
kasan_check_write(to, n);
res = raw_copy_from_user(to, from, n);
}
if (unlikely(res))
memset(to + (n - res), 0, res);
return res;
}
EXPORT_SYMBOL(_copy_from_user);
#endif
#ifndef INLINE_COPY_TO_USER
unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
{
might_fault();
if (likely(access_ok(to, n))) {
kasan_check_read(from, n);
n = raw_copy_to_user(to, from, n);
}
return n;
}
EXPORT_SYMBOL(_copy_to_user);
#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)
{
unsigned long val;
uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
if (unlikely(size == 0))
return 1;
from -= align;
size += align;
if (!user_read_access_begin(from, size))
return -EFAULT;
unsafe_get_user(val, (unsigned long __user *) from, err_fault);
if (align)
val &= ~aligned_byte_mask(align);
while (size > sizeof(unsigned long)) {
if (unlikely(val))
goto done;
from += sizeof(unsigned long);
size -= sizeof(unsigned long);
unsafe_get_user(val, (unsigned long __user *) from, err_fault);
}
if (size < sizeof(unsigned long))
val &= aligned_byte_mask(size);
done:
user_read_access_end();
return (val == 0);
err_fault:
user_read_access_end();
return -EFAULT;
}
EXPORT_SYMBOL(check_zeroed_user);
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