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

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