1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License as published by
4  * the Free Software Foundation; either version 2 of the License, or
5  * (at your option) any later version.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * along with this program; if not, write to the Free Software
14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
15  *
16  * Copyright (C) IBM Corporation, 2010
17  *
18  * Author: Anton Blanchard <anton@au.ibm.com>
19  */
20 #include <linux/export.h>
21 #include <linux/compiler.h>
22 #include <linux/types.h>
23 #include <asm/checksum.h>
24 #include <linux/uaccess.h>
25 
26 __wsum csum_and_copy_from_user(const void __user *src, void *dst,
27 			       int len, __wsum sum, int *err_ptr)
28 {
29 	unsigned int csum;
30 
31 	might_sleep();
32 
33 	*err_ptr = 0;
34 
35 	if (!len) {
36 		csum = 0;
37 		goto out;
38 	}
39 
40 	if (unlikely((len < 0) || !access_ok(VERIFY_READ, src, len))) {
41 		*err_ptr = -EFAULT;
42 		csum = (__force unsigned int)sum;
43 		goto out;
44 	}
45 
46 	csum = csum_partial_copy_generic((void __force *)src, dst,
47 					 len, sum, err_ptr, NULL);
48 
49 	if (unlikely(*err_ptr)) {
50 		int missing = __copy_from_user(dst, src, len);
51 
52 		if (missing) {
53 			memset(dst + len - missing, 0, missing);
54 			*err_ptr = -EFAULT;
55 		} else {
56 			*err_ptr = 0;
57 		}
58 
59 		csum = csum_partial(dst, len, sum);
60 	}
61 
62 out:
63 	return (__force __wsum)csum;
64 }
65 EXPORT_SYMBOL(csum_and_copy_from_user);
66 
67 __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
68 			     __wsum sum, int *err_ptr)
69 {
70 	unsigned int csum;
71 
72 	might_sleep();
73 
74 	*err_ptr = 0;
75 
76 	if (!len) {
77 		csum = 0;
78 		goto out;
79 	}
80 
81 	if (unlikely((len < 0) || !access_ok(VERIFY_WRITE, dst, len))) {
82 		*err_ptr = -EFAULT;
83 		csum = -1; /* invalid checksum */
84 		goto out;
85 	}
86 
87 	csum = csum_partial_copy_generic(src, (void __force *)dst,
88 					 len, sum, NULL, err_ptr);
89 
90 	if (unlikely(*err_ptr)) {
91 		csum = csum_partial(src, len, sum);
92 
93 		if (copy_to_user(dst, src, len)) {
94 			*err_ptr = -EFAULT;
95 			csum = -1; /* invalid checksum */
96 		}
97 	}
98 
99 out:
100 	return (__force __wsum)csum;
101 }
102 EXPORT_SYMBOL(csum_and_copy_to_user);
103