[linux-block.git] / 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)
{
	return _inline_copy_from_user(to, from, n);
}
EXPORT_SYMBOL(_copy_from_user);
#endif

#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
{
	return _inline_copy_to_user(to, from, 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);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
5671dca2 AS	2	#include <linux/compiler.h>
	3	#include <linux/errno.h>
	4	#include <linux/export.h>
4d0e9df5	5	#include <linux/fault-inject-usercopy.h>
76d6f06c	6	#include <linux/instrumented.h>
5671dca2 AS	7	#include <linux/kernel.h>
	8	#include <linux/nospec.h>
	9	#include <linux/string.h>
76d6f06c	10	#include <linux/uaccess.h>
9f2c2d6b	11	#include <linux/wordpart.h>
d597580d AV	12
	13	/* out-of-line parts */
	14
1f9a8286	15	#if !defined(INLINE_COPY_FROM_USER) \|\| defined(CONFIG_RUST)
d597580d AV	16	unsigned long _copy_from_user(void to, const void __user from, unsigned long n)
d597580d AV	17	{
1f9a8286	18	return _inline_copy_from_user(to, from, n);
d597580d AV	19	}
	20	EXPORT_SYMBOL(_copy_from_user);
	21	#endif
	22
1f9a8286	23	#if !defined(INLINE_COPY_TO_USER) \|\| defined(CONFIG_RUST)
a0e94598	24	unsigned long _copy_to_user(void __user to, const void from, unsigned long n)
d597580d	25	{
1f9a8286	26	return _inline_copy_to_user(to, from, n);
d597580d AV	27	}
	28	EXPORT_SYMBOL(_copy_to_user);
	29	#endif
f5a1a536 AS	30
	31	/**
	32	* check_zeroed_user: check if a userspace buffer only contains zero bytes
	33	* @from: Source address, in userspace.
	34	* @size: Size of buffer.
	35	*
	36	* This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
	37	* userspace addresses (and is more efficient because we don't care where the
	38	* first non-zero byte is).
	39	*
	40	* Returns:
	41	* * 0: There were non-zero bytes present in the buffer.
	42	* * 1: The buffer was full of zero bytes.
	43	* * -EFAULT: access to userspace failed.
	44	*/
	45	int check_zeroed_user(const void __user *from, size_t size)
	46	{
	47	unsigned long val;
	48	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
	49
	50	if (unlikely(size == 0))
	51	return 1;
	52
	53	from -= align;
	54	size += align;
	55
41cd7805	56	if (!user_read_access_begin(from, size))
f5a1a536 AS	57	return -EFAULT;
	58
	59	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
	60	if (align)
	61	val &= ~aligned_byte_mask(align);
	62
	63	while (size > sizeof(unsigned long)) {
	64	if (unlikely(val))
	65	goto done;
	66
	67	from += sizeof(unsigned long);
	68	size -= sizeof(unsigned long);
	69
	70	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
	71	}
	72
	73	if (size < sizeof(unsigned long))
	74	val &= aligned_byte_mask(size);
	75
	76	done:
41cd7805	77	user_read_access_end();
f5a1a536 AS	78	return (val == 0);
f5a1a536 AS	79	err_fault:
41cd7805	80	user_read_access_end();
f5a1a536 AS	81	return -EFAULT;
	82	}
	83	EXPORT_SYMBOL(check_zeroed_user);