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_before(to, from, n);
16 res = raw_copy_from_user(to, from, n);
17 instrument_copy_from_user_after(to, from, n, res);
18 }
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
_copy_to_user(void __user * to,const void * from,unsigned long n)27 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
28 {
29 might_fault();
30 if (should_fail_usercopy())
31 return n;
32 if (likely(access_ok(to, n))) {
33 instrument_copy_to_user(to, from, n);
34 n = raw_copy_to_user(to, from, n);
35 }
36 return n;
37 }
38 EXPORT_SYMBOL(_copy_to_user);
39 #endif
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 */
check_zeroed_user(const void __user * from,size_t size)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
66 if (!user_read_access_begin(from, size))
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:
87 user_read_access_end();
88 return (val == 0);
89 err_fault:
90 user_read_access_end();
91 return -EFAULT;
92 }
93 EXPORT_SYMBOL(check_zeroed_user);
94
