[linux-block.git] / lib / usercopy.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>

/* 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))) {
		instrument_copy_from_user_before(to, from, n);
		res = raw_copy_from_user(to, from, n);
		instrument_copy_from_user_after(to, from, n, res);
	}
	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);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
f5a1a536	2	#include <linux/bitops.h>
4d0e9df5	3	#include <linux/fault-inject-usercopy.h>
76d6f06c ME	4	#include <linux/instrumented.h>
76d6f06c ME	5	#include <linux/uaccess.h>
d597580d AV	6
	7	/* out-of-line parts */
	8
	9	#ifndef INLINE_COPY_FROM_USER
	10	unsigned long _copy_from_user(void to, const void __user from, unsigned long n)
	11	{
	12	unsigned long res = n;
9c5f6908	13	might_fault();
4d0e9df5	14	if (!should_fail_usercopy() && likely(access_ok(from, n))) {
33b75c1d	15	instrument_copy_from_user_before(to, from, n);
d597580d	16	res = raw_copy_from_user(to, from, n);
33b75c1d	17	instrument_copy_from_user_after(to, from, n, res);
9c5f6908	18	}
d597580d AV	19	if (unlikely(res))
	20	memset(to + (n - res), 0, res);
	21	return res;
	22	}
	23	EXPORT_SYMBOL(_copy_from_user);
	24	#endif
	25
	26	#ifndef INLINE_COPY_TO_USER
a0e94598	27	unsigned long _copy_to_user(void __user to, const void from, unsigned long n)
d597580d	28	{
9c5f6908	29	might_fault();
4d0e9df5 AL	30	if (should_fail_usercopy())
4d0e9df5 AL	31	return n;
96d4f267	32	if (likely(access_ok(to, n))) {
76d6f06c	33	instrument_copy_to_user(to, from, n);
d597580d	34	n = raw_copy_to_user(to, from, n);
9c5f6908	35	}
d597580d AV	36	return n;
	37	}
	38	EXPORT_SYMBOL(_copy_to_user);
	39	#endif
f5a1a536 AS	40
	41	/**
	42	* check_zeroed_user: check if a userspace buffer only contains zero bytes
	43	* @from: Source address, in userspace.
	44	* @size: Size of buffer.
	45	*
	46	* This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
	47	* userspace addresses (and is more efficient because we don't care where the
	48	* first non-zero byte is).
	49	*
	50	* Returns:
	51	* * 0: There were non-zero bytes present in the buffer.
	52	* * 1: The buffer was full of zero bytes.
	53	* * -EFAULT: access to userspace failed.
	54	*/
	55	int check_zeroed_user(const void __user *from, size_t size)
	56	{
	57	unsigned long val;
	58	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
	59
	60	if (unlikely(size == 0))
	61	return 1;
	62
	63	from -= align;
	64	size += align;
	65
41cd7805	66	if (!user_read_access_begin(from, size))
f5a1a536 AS	67	return -EFAULT;
	68
	69	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
	70	if (align)
	71	val &= ~aligned_byte_mask(align);
	72
	73	while (size > sizeof(unsigned long)) {
	74	if (unlikely(val))
	75	goto done;
	76
	77	from += sizeof(unsigned long);
	78	size -= sizeof(unsigned long);
	79
	80	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
	81	}
	82
	83	if (size < sizeof(unsigned long))
	84	val &= aligned_byte_mask(size);
	85
	86	done:
41cd7805	87	user_read_access_end();
f5a1a536 AS	88	return (val == 0);
f5a1a536 AS	89	err_fault:
41cd7805	90	user_read_access_end();
f5a1a536 AS	91	return -EFAULT;
	92	}
	93	EXPORT_SYMBOL(check_zeroed_user);