[lttng-modules.git] / include / wrapper / uaccess.h

/* 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 */
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
80bb2600 MJ	2	*
	3	* wrapper/uaccess.h
	4	*
	5	* wrapper around linux/uaccess.h.
	6	*
	7	* Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
	8	*/
	9
	10	#ifndef _LTTNG_WRAPPER_UACCESS_H
	11	#define _LTTNG_WRAPPER_UACCESS_H
	12
	13	#include <linux/uaccess.h>
31815820	14	#include <wrapper/bitops.h>
2df37e95	15	#include <lttng/kernel-version.h>
80bb2600	16
5f4c791e	17	#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) \|\| \
52cb3b84	18	LTTNG_RHEL_KERNEL_RANGE(4,18,0,147,0,0, 4,19,0,0,0,0))
80bb2600 MJ	19
	20	#define VERIFY_READ 0
	21	#define VERIFY_WRITE 1
	22	#define lttng_access_ok(type, addr, size) access_ok(addr, size)
	23
5f4c791e	24	#else /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) */
80bb2600 MJ	25
	26	#define lttng_access_ok(type, addr, size) access_ok(type, addr, size)
	27
5f4c791e	28	#endif /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,0,0) */
80bb2600	29
148f58fe MD	30	#if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0)
	31	static __always_inline __must_check int
	32	lttng_copy_struct_from_user(void dst, size_t ksize, const void __user src,
	33	size_t usize)
	34	{
	35	return copy_struct_from_user(dst, ksize, src, usize);
	36	}
	37	#else /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0) */
	38	/**
	39	* lttng_check_zeroed_user: check if a userspace buffer only contains zero bytes
	40	* @from: Source address, in userspace.
	41	* @size: Size of buffer.
	42	*
	43	* This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
	44	* userspace addresses (and is more efficient because we don't care where the
	45	* first non-zero byte is).
	46	*
	47	* Returns:
	48	* * 0: There were non-zero bytes present in the buffer.
	49	* * 1: The buffer was full of zero bytes.
	50	* * -EFAULT: access to userspace failed.
	51	*/
31815820	52	static inline
148f58fe MD	53	int lttng_check_zeroed_user(const void __user *from, size_t size)
	54	{
	55	unsigned long val;
	56	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
	57	int ret;
	58
	59	if (unlikely(size == 0))
	60	return 1;
	61
	62	from -= align;
	63	size += align;
	64
31815820	65	if (!lttng_access_ok(VERIFY_READ, from, size))
148f58fe MD	66	return -EFAULT;
	67
	68	ret = get_user(val, (unsigned long __user *) from);
	69	if (ret)
	70	return ret;
	71	if (align)
31815820	72	val &= ~lttng_aligned_byte_mask(align);
148f58fe MD	73
	74	while (size > sizeof(unsigned long)) {
	75	if (unlikely(val))
	76	goto done;
	77
	78	from += sizeof(unsigned long);
	79	size -= sizeof(unsigned long);
	80
	81	ret = get_user(val, (unsigned long __user *) from);
	82	if (ret)
	83	return ret;
	84	}
	85
	86	if (size < sizeof(unsigned long))
31815820	87	val &= lttng_aligned_byte_mask(size);
148f58fe MD	88
	89	done:
	90	return (val == 0);
	91	}
	92
	93	static __always_inline __must_check int
	94	lttng_copy_struct_from_user(void dst, size_t ksize, const void __user src,
	95	size_t usize)
	96	{
	97	size_t size = min(ksize, usize);
	98	size_t rest = max(ksize, usize) - size;
	99
	100	/* Deal with trailing bytes. */
	101	if (usize < ksize) {
	102	memset(dst + size, 0, rest);
	103	} else if (usize > ksize) {
	104	int ret = lttng_check_zeroed_user(src + size, rest);
	105	if (ret <= 0)
	106	return ret ?: -E2BIG;
	107	}
	108	/* Copy the interoperable parts of the struct. */
	109	if (copy_from_user(dst, src, size))
	110	return -EFAULT;
	111	return 0;
	112	}
	113	#endif /* LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0) */
	114
80bb2600	115	#endif /* _LTTNG_WRAPPER_UACCESS_H */