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 <asm/uaccess.h>
26 #include <asm/checksum.h>
27
28 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
29 static inline
csum_and_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)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
csum_and_copy_to_user(const void * src,void __user * dst,int len,__wsum sum,int * err_ptr)44 static __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
csum_add(__wsum csum,__wsum addend)61 static 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
csum_sub(__wsum csum,__wsum addend)69 static inline __wsum csum_sub(__wsum csum, __wsum addend)
70 {
71 return csum_add(csum, ~addend);
72 }
73
csum16_add(__sum16 csum,__be16 addend)74 static 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
csum16_sub(__sum16 csum,__be16 addend)82 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
83 {
84 return csum16_add(csum, ~addend);
85 }
86
87 static inline __wsum
csum_block_add(__wsum csum,__wsum csum2,int offset)88 csum_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
99 static inline __wsum
csum_block_add_ext(__wsum csum,__wsum csum2,int offset,int len)100 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
101 {
102 return csum_block_add(csum, csum2, offset);
103 }
104
105 static inline __wsum
csum_block_sub(__wsum csum,__wsum csum2,int offset)106 csum_block_sub(__wsum csum, __wsum csum2, int offset)
107 {
108 return csum_block_add(csum, ~csum2, offset);
109 }
110
csum_unfold(__sum16 n)111 static inline __wsum csum_unfold(__sum16 n)
112 {
113 return (__force __wsum)n;
114 }
115
csum_partial_ext(const void * buff,int len,__wsum sum)116 static 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
csum_replace_by_diff(__sum16 * sum,__wsum diff)123 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
124 {
125 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
126 }
127
csum_replace4(__sum16 * sum,__be32 from,__be32 to)128 static 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 */
csum_replace2(__sum16 * sum,__be16 old,__be16 new)141 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
142 {
143 *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
144 }
145
146 struct sk_buff;
147 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
148 __be32 from, __be32 to, bool pseudohdr);
149 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
150 const __be32 *from, const __be32 *to,
151 bool pseudohdr);
152 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
153 __wsum diff, bool pseudohdr);
154
inet_proto_csum_replace2(__sum16 * sum,struct sk_buff * skb,__be16 from,__be16 to,bool pseudohdr)155 static 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
remcsum_adjust(void * ptr,__wsum csum,int start,int offset)163 static 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
remcsum_unadjust(__sum16 * psum,__wsum delta)180 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
181 {
182 *psum = csum_fold(csum_sub(delta, *psum));
183 }
184
185 #endif
186