1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright (C) IBM Corporation, 2010
5 *
6 * Author: Anton Blanchard <anton@au.ibm.com>
7 */
8 #include <linux/export.h>
9 #include <linux/compiler.h>
10 #include <linux/types.h>
11 #include <asm/checksum.h>
12 #include <linux/uaccess.h>
13
csum_and_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)14 __wsum csum_and_copy_from_user(const void __user *src, void *dst,
15 int len, __wsum sum, int *err_ptr)
16 {
17 unsigned int csum;
18
19 might_sleep();
20 allow_read_from_user(src, len);
21
22 *err_ptr = 0;
23
24 if (!len) {
25 csum = 0;
26 goto out;
27 }
28
29 if (unlikely((len < 0) || !access_ok(src, len))) {
30 *err_ptr = -EFAULT;
31 csum = (__force unsigned int)sum;
32 goto out;
33 }
34
35 csum = csum_partial_copy_generic((void __force *)src, dst,
36 len, sum, err_ptr, NULL);
37
38 if (unlikely(*err_ptr)) {
39 int missing = __copy_from_user(dst, src, len);
40
41 if (missing) {
42 memset(dst + len - missing, 0, missing);
43 *err_ptr = -EFAULT;
44 } else {
45 *err_ptr = 0;
46 }
47
48 csum = csum_partial(dst, len, sum);
49 }
50
51 out:
52 prevent_read_from_user(src, len);
53 return (__force __wsum)csum;
54 }
55 EXPORT_SYMBOL(csum_and_copy_from_user);
56
csum_and_copy_to_user(const void * src,void __user * dst,int len,__wsum sum,int * err_ptr)57 __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
58 __wsum sum, int *err_ptr)
59 {
60 unsigned int csum;
61
62 might_sleep();
63 allow_write_to_user(dst, len);
64
65 *err_ptr = 0;
66
67 if (!len) {
68 csum = 0;
69 goto out;
70 }
71
72 if (unlikely((len < 0) || !access_ok(dst, len))) {
73 *err_ptr = -EFAULT;
74 csum = -1; /* invalid checksum */
75 goto out;
76 }
77
78 csum = csum_partial_copy_generic(src, (void __force *)dst,
79 len, sum, NULL, err_ptr);
80
81 if (unlikely(*err_ptr)) {
82 csum = csum_partial(src, len, sum);
83
84 if (copy_to_user(dst, src, len)) {
85 *err_ptr = -EFAULT;
86 csum = -1; /* invalid checksum */
87 }
88 }
89
90 out:
91 prevent_write_to_user(dst, len);
92 return (__force __wsum)csum;
93 }
94 EXPORT_SYMBOL(csum_and_copy_to_user);
95
