100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/bitops.h>
|
|
#include <linux/fault-inject-usercopy.h>
|
|
#include <linux/instrumented.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/nospec.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 (!should_fail_usercopy() && likely(access_ok(from, n))) {
|
|
/*
|
|
* Ensure that bad access_ok() speculation will not
|
|
* lead to nasty side effects *after* the copy is
|
|
* finished:
|
|
*/
|
|
barrier_nospec();
|
|
instrument_copy_from_user(to, from, 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 (should_fail_usercopy())
|
|
return n;
|
|
if (likely(access_ok(to, n))) {
|
|
instrument_copy_to_user(to, 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);
|