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 <asm/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
62out:
63	return (__force __wsum)csum;
64}
65EXPORT_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
99out:
100	return (__force __wsum)csum;
101}
102EXPORT_SYMBOL(csum_and_copy_to_user);
103