1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET is implemented using the  BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  *		Checksumming functions for IP, TCP, UDP and so on
8  *
9  * Authors:	Jorge Cwik, <jorge@laser.satlink.net>
10  *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
11  *		Borrows very liberally from tcp.c and ip.c, see those
12  *		files for more names.
13  */
14 
15 #ifndef _CHECKSUM_H
16 #define _CHECKSUM_H
17 
18 #include <linux/errno.h>
19 #include <asm/types.h>
20 #include <asm/byteorder.h>
21 #include <linux/uaccess.h>
22 #include <asm/checksum.h>
23 
24 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
25 static inline
csum_and_copy_from_user(const void __user * src,void * dst,int len)26 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
27 				      int len)
28 {
29 	if (copy_from_user(dst, src, len))
30 		return 0;
31 	return csum_partial(dst, len, ~0U);
32 }
33 #endif
34 
35 #ifndef HAVE_CSUM_COPY_USER
csum_and_copy_to_user(const void * src,void __user * dst,int len)36 static __inline__ __wsum csum_and_copy_to_user
37 (const void *src, void __user *dst, int len)
38 {
39 	__wsum sum = csum_partial(src, len, ~0U);
40 
41 	if (copy_to_user(dst, src, len) == 0)
42 		return sum;
43 	return 0;
44 }
45 #endif
46 
47 #ifndef _HAVE_ARCH_CSUM_AND_COPY
48 static inline __wsum
csum_partial_copy_nocheck(const void * src,void * dst,int len)49 csum_partial_copy_nocheck(const void *src, void *dst, int len)
50 {
51 	memcpy(dst, src, len);
52 	return csum_partial(dst, len, 0);
53 }
54 #endif
55 
56 #ifndef HAVE_ARCH_CSUM_ADD
csum_add(__wsum csum,__wsum addend)57 static inline __wsum csum_add(__wsum csum, __wsum addend)
58 {
59 	u32 res = (__force u32)csum;
60 	res += (__force u32)addend;
61 	return (__force __wsum)(res + (res < (__force u32)addend));
62 }
63 #endif
64 
csum_sub(__wsum csum,__wsum addend)65 static inline __wsum csum_sub(__wsum csum, __wsum addend)
66 {
67 	return csum_add(csum, ~addend);
68 }
69 
csum16_add(__sum16 csum,__be16 addend)70 static inline __sum16 csum16_add(__sum16 csum, __be16 addend)
71 {
72 	u16 res = (__force u16)csum;
73 
74 	res += (__force u16)addend;
75 	return (__force __sum16)(res + (res < (__force u16)addend));
76 }
77 
csum16_sub(__sum16 csum,__be16 addend)78 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
79 {
80 	return csum16_add(csum, ~addend);
81 }
82 
csum_shift(__wsum sum,int offset)83 static inline __wsum csum_shift(__wsum sum, int offset)
84 {
85 	/* rotate sum to align it with a 16b boundary */
86 	if (offset & 1)
87 		return (__force __wsum)ror32((__force u32)sum, 8);
88 	return sum;
89 }
90 
91 static inline __wsum
csum_block_add(__wsum csum,__wsum csum2,int offset)92 csum_block_add(__wsum csum, __wsum csum2, int offset)
93 {
94 	return csum_add(csum, csum_shift(csum2, offset));
95 }
96 
97 static inline __wsum
csum_block_add_ext(__wsum csum,__wsum csum2,int offset,int len)98 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
99 {
100 	return csum_block_add(csum, csum2, offset);
101 }
102 
103 static inline __wsum
csum_block_sub(__wsum csum,__wsum csum2,int offset)104 csum_block_sub(__wsum csum, __wsum csum2, int offset)
105 {
106 	return csum_block_add(csum, ~csum2, offset);
107 }
108 
csum_unfold(__sum16 n)109 static inline __wsum csum_unfold(__sum16 n)
110 {
111 	return (__force __wsum)n;
112 }
113 
csum_partial_ext(const void * buff,int len,__wsum sum)114 static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
115 {
116 	return csum_partial(buff, len, sum);
117 }
118 
119 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
120 
csum_replace_by_diff(__sum16 * sum,__wsum diff)121 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
122 {
123 	*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
124 }
125 
csum_replace4(__sum16 * sum,__be32 from,__be32 to)126 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
127 {
128 	__wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
129 
130 	*sum = csum_fold(csum_add(tmp, (__force __wsum)to));
131 }
132 
133 /* Implements RFC 1624 (Incremental Internet Checksum)
134  * 3. Discussion states :
135  *     HC' = ~(~HC + ~m + m')
136  *  m : old value of a 16bit field
137  *  m' : new value of a 16bit field
138  */
csum_replace2(__sum16 * sum,__be16 old,__be16 new)139 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
140 {
141 	*sum = ~csum16_add(csum16_sub(~(*sum), old), new);
142 }
143 
144 struct sk_buff;
145 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
146 			      __be32 from, __be32 to, bool pseudohdr);
147 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
148 			       const __be32 *from, const __be32 *to,
149 			       bool pseudohdr);
150 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
151 				     __wsum diff, bool pseudohdr);
152 
inet_proto_csum_replace2(__sum16 * sum,struct sk_buff * skb,__be16 from,__be16 to,bool pseudohdr)153 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
154 					    __be16 from, __be16 to,
155 					    bool pseudohdr)
156 {
157 	inet_proto_csum_replace4(sum, skb, (__force __be32)from,
158 				 (__force __be32)to, pseudohdr);
159 }
160 
remcsum_adjust(void * ptr,__wsum csum,int start,int offset)161 static inline __wsum remcsum_adjust(void *ptr, __wsum csum,
162 				    int start, int offset)
163 {
164 	__sum16 *psum = (__sum16 *)(ptr + offset);
165 	__wsum delta;
166 
167 	/* Subtract out checksum up to start */
168 	csum = csum_sub(csum, csum_partial(ptr, start, 0));
169 
170 	/* Set derived checksum in packet */
171 	delta = csum_sub((__force __wsum)csum_fold(csum),
172 			 (__force __wsum)*psum);
173 	*psum = csum_fold(csum);
174 
175 	return delta;
176 }
177 
remcsum_unadjust(__sum16 * psum,__wsum delta)178 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
179 {
180 	*psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
181 }
182 
183 #endif
184