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
_copy_from_user(void * to,const void __user * from,unsigned long n)10 unsigned 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 }
22 EXPORT_SYMBOL(_copy_from_user);
23 #endif
24
25 #ifndef INLINE_COPY_TO_USER
_copy_to_user(void __user * to,const void * from,unsigned long n)26 unsigned 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 }
37 EXPORT_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 */
check_zeroed_user(const void __user * from,size_t size)54 int 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
85 done:
86 user_read_access_end();
87 return (val == 0);
88 err_fault:
89 user_read_access_end();
90 return -EFAULT;
91 }
92 EXPORT_SYMBOL(check_zeroed_user);
93