1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compiler.h>
3 #include <linux/errno.h>
4 #include <linux/export.h>
5 #include <linux/fault-inject-usercopy.h>
6 #include <linux/instrumented.h>
7 #include <linux/kernel.h>
8 #include <linux/nospec.h>
9 #include <linux/string.h>
10 #include <linux/uaccess.h>
11 #include <linux/wordpart.h>
12
13 /* out-of-line parts */
14
15 #if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)
16 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
17 {
18 return _inline_copy_from_user(to, from, n);
19 }
20 EXPORT_SYMBOL(_copy_from_user);
21 #endif
22
23 #if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
24 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
25 {
26 return _inline_copy_to_user(to, from, n);
27 }
28 EXPORT_SYMBOL(_copy_to_user);
29 #endif
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
56 if (!user_read_access_begin(from, size))
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:
77 user_read_access_end();
78 return (val == 0);
79 err_fault:
80 user_read_access_end();
81 return -EFAULT;
82 }
83 EXPORT_SYMBOL(check_zeroed_user);
84
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