1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Checksumming functions for IP, TCP, UDP and so on
7 *
8 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10 * Borrows very liberally from tcp.c and ip.c, see those
11 * files for more names.
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18
19#ifndef _CHECKSUM_H
20#define _CHECKSUM_H
21
22#include <linux/errno.h>
23#include <asm/types.h>
24#include <asm/byteorder.h>
25#include <linux/uaccess.h>
26#include <asm/checksum.h>
27
28#ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
29static inline
30__wsum csum_and_copy_from_user (const void __user *src, void *dst,
31 int len, __wsum sum, int *err_ptr)
32{
33 if (access_ok(VERIFY_READ, src, len))
34 return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
35
36 if (len)
37 *err_ptr = -EFAULT;
38
39 return sum;
40}
41#endif
42
43#ifndef HAVE_CSUM_COPY_USER
44static __inline__ __wsum csum_and_copy_to_user
45(const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
46{
47 sum = csum_partial(src, len, sum);
48
49 if (access_ok(VERIFY_WRITE, dst, len)) {
50 if (copy_to_user(dst, src, len) == 0)
51 return sum;
52 }
53 if (len)
54 *err_ptr = -EFAULT;
55
56 return (__force __wsum)-1; /* invalid checksum */
57}
58#endif
59
60#ifndef HAVE_ARCH_CSUM_ADD
61static inline __wsum csum_add(__wsum csum, __wsum addend)
62{
63 u32 res = (__force u32)csum;
64 res += (__force u32)addend;
65 return (__force __wsum)(res + (res < (__force u32)addend));
66}
67#endif
68
69static inline __wsum csum_sub(__wsum csum, __wsum addend)
70{
71 return csum_add(csum, ~addend);
72}
73
74static inline __sum16 csum16_add(__sum16 csum, __be16 addend)
75{
76 u16 res = (__force u16)csum;
77
78 res += (__force u16)addend;
79 return (__force __sum16)(res + (res < (__force u16)addend));
80}
81
82static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
83{
84 return csum16_add(csum, ~addend);
85}
86
87static inline __wsum
88csum_block_add(__wsum csum, __wsum csum2, int offset)
89{
90 u32 sum = (__force u32)csum2;
91
92 /* rotate sum to align it with a 16b boundary */
93 if (offset & 1)
94 sum = ror32(sum, 8);
95
96 return csum_add(csum, (__force __wsum)sum);
97}
98
99static inline __wsum
100csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
101{
102 return csum_block_add(csum, csum2, offset);
103}
104
105static inline __wsum
106csum_block_sub(__wsum csum, __wsum csum2, int offset)
107{
108 return csum_block_add(csum, ~csum2, offset);
109}
110
111static inline __wsum csum_unfold(__sum16 n)
112{
113 return (__force __wsum)n;
114}
115
116static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
117{
118 return csum_partial(buff, len, sum);
119}
120
121#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
122
123static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
124{
125 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
126}
127
128static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
129{
130 __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
131
132 *sum = csum_fold(csum_add(tmp, (__force __wsum)to));
133}
134
135/* Implements RFC 1624 (Incremental Internet Checksum)
136 * 3. Discussion states :
137 * HC' = ~(~HC + ~m + m')
138 * m : old value of a 16bit field
139 * m' : new value of a 16bit field
140 */
141static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
142{
143 *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
144}
145
146struct sk_buff;
147void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
148 __be32 from, __be32 to, bool pseudohdr);
149void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
150 const __be32 *from, const __be32 *to,
151 bool pseudohdr);
152void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
153 __wsum diff, bool pseudohdr);
154
155static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
156 __be16 from, __be16 to,
157 bool pseudohdr)
158{
159 inet_proto_csum_replace4(sum, skb, (__force __be32)from,
160 (__force __be32)to, pseudohdr);
161}
162
163static inline __wsum remcsum_adjust(void *ptr, __wsum csum,
164 int start, int offset)
165{
166 __sum16 *psum = (__sum16 *)(ptr + offset);
167 __wsum delta;
168
169 /* Subtract out checksum up to start */
170 csum = csum_sub(csum, csum_partial(ptr, start, 0));
171
172 /* Set derived checksum in packet */
173 delta = csum_sub((__force __wsum)csum_fold(csum),
174 (__force __wsum)*psum);
175 *psum = csum_fold(csum);
176
177 return delta;
178}
179
180static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
181{
182 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
183}
184
185#endif
186