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/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
*
* wrapper/uaccess.h
*
* wrapper around linux/uaccess.h.
*
* Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
*/
#ifndef _LTTNG_WRAPPER_UACCESS_H
#define _LTTNG_WRAPPER_UACCESS_H
#include <linux/uaccess.h>
#include <wrapper/bitops.h>
#include <lttng/kernel-version.h>
#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) || \
LTTNG_RHEL_KERNEL_RANGE(4,18,0,147,0,0, 4,19,0,0,0,0))
#define VERIFY_READ 0
#define VERIFY_WRITE 1
#define lttng_access_ok(type, addr, size) access_ok(addr, size)
#else /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) */
#define lttng_access_ok(type, addr, size) access_ok(type, addr, size)
#endif /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) */
#if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0)
static __always_inline __must_check int
lttng_copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
size_t usize)
{
return copy_struct_from_user(dst, ksize, src, usize);
}
#else /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0) */
/**
* lttng_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.
*/
static inline
int lttng_check_zeroed_user(const void __user *from, size_t size)
{
unsigned long val;
uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
int ret;
if (unlikely(size == 0))
return 1;
from -= align;
size += align;
if (!lttng_access_ok(VERIFY_READ, from, size))
return -EFAULT;
ret = get_user(val, (unsigned long __user *) from);
if (ret)
return ret;
if (align)
val &= ~lttng_aligned_byte_mask(align);
while (size > sizeof(unsigned long)) {
if (unlikely(val))
goto done;
from += sizeof(unsigned long);
size -= sizeof(unsigned long);
ret = get_user(val, (unsigned long __user *) from);
if (ret)
return ret;
}
if (size < sizeof(unsigned long))
val &= lttng_aligned_byte_mask(size);
done:
return (val == 0);
}
static __always_inline __must_check int
lttng_copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
size_t usize)
{
size_t size = min(ksize, usize);
size_t rest = max(ksize, usize) - size;
/* Deal with trailing bytes. */
if (usize < ksize) {
memset(dst + size, 0, rest);
} else if (usize > ksize) {
int ret = lttng_check_zeroed_user(src + size, rest);
if (ret <= 0)
return ret ?: -E2BIG;
}
/* Copy the interoperable parts of the struct. */
if (copy_from_user(dst, src, size))
return -EFAULT;
return 0;
}
#endif /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0) */
#endif /* _LTTNG_WRAPPER_UACCESS_H */
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