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 <asm/checksum.h>
22 #if !defined(_HAVE_ARCH_COPY_AND_CSUM_FROM_USER) || !defined(HAVE_CSUM_COPY_USER)
23 #include <linux/uaccess.h>
24 #endif
25 
26 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
27 static __always_inline
csum_and_copy_from_user(const void __user * src,void * dst,int len)28 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
29 				      int len)
30 {
31 	if (copy_from_user(dst, src, len))
32 		return 0;
33 	return csum_partial(dst, len, ~0U);
34 }
35 #endif
36 
37 #ifndef HAVE_CSUM_COPY_USER
csum_and_copy_to_user(const void * src,void __user * dst,int len)38 static __always_inline __wsum csum_and_copy_to_user
39 (const void *src, void __user *dst, int len)
40 {
41 	__wsum sum = csum_partial(src, len, ~0U);
42 
43 	if (copy_to_user(dst, src, len) == 0)
44 		return sum;
45 	return 0;
46 }
47 #endif
48 
49 #ifndef _HAVE_ARCH_CSUM_AND_COPY
50 static __always_inline __wsum
csum_partial_copy_nocheck(const void * src,void * dst,int len)51 csum_partial_copy_nocheck(const void *src, void *dst, int len)
52 {
53 	memcpy(dst, src, len);
54 	return csum_partial(dst, len, 0);
55 }
56 #endif
57 
58 #ifndef HAVE_ARCH_CSUM_ADD
csum_add(__wsum csum,__wsum addend)59 static __always_inline __wsum csum_add(__wsum csum, __wsum addend)
60 {
61 	u32 res = (__force u32)csum;
62 	res += (__force u32)addend;
63 	return (__force __wsum)(res + (res < (__force u32)addend));
64 }
65 #endif
66 
csum_sub(__wsum csum,__wsum addend)67 static __always_inline __wsum csum_sub(__wsum csum, __wsum addend)
68 {
69 	return csum_add(csum, ~addend);
70 }
71 
csum16_add(__sum16 csum,__be16 addend)72 static __always_inline __sum16 csum16_add(__sum16 csum, __be16 addend)
73 {
74 	u16 res = (__force u16)csum;
75 
76 	res += (__force u16)addend;
77 	return (__force __sum16)(res + (res < (__force u16)addend));
78 }
79 
csum16_sub(__sum16 csum,__be16 addend)80 static __always_inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
81 {
82 	return csum16_add(csum, ~addend);
83 }
84 
85 #ifndef HAVE_ARCH_CSUM_SHIFT
csum_shift(__wsum sum,int offset)86 static __always_inline __wsum csum_shift(__wsum sum, int offset)
87 {
88 	/* rotate sum to align it with a 16b boundary */
89 	if (offset & 1)
90 		return (__force __wsum)ror32((__force u32)sum, 8);
91 	return sum;
92 }
93 #endif
94 
95 static __always_inline __wsum
csum_block_add(__wsum csum,__wsum csum2,int offset)96 csum_block_add(__wsum csum, __wsum csum2, int offset)
97 {
98 	return csum_add(csum, csum_shift(csum2, offset));
99 }
100 
101 static __always_inline __wsum
csum_block_add_ext(__wsum csum,__wsum csum2,int offset,int len)102 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
103 {
104 	return csum_block_add(csum, csum2, offset);
105 }
106 
107 static __always_inline __wsum
csum_block_sub(__wsum csum,__wsum csum2,int offset)108 csum_block_sub(__wsum csum, __wsum csum2, int offset)
109 {
110 	return csum_block_add(csum, ~csum2, offset);
111 }
112 
csum_unfold(__sum16 n)113 static __always_inline __wsum csum_unfold(__sum16 n)
114 {
115 	return (__force __wsum)n;
116 }
117 
118 static __always_inline
csum_partial_ext(const void * buff,int len,__wsum sum)119 __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
120 {
121 	return csum_partial(buff, len, sum);
122 }
123 
124 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
125 
csum_replace_by_diff(__sum16 * sum,__wsum diff)126 static __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
127 {
128 	*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
129 }
130 
csum_replace4(__sum16 * sum,__be32 from,__be32 to)131 static __always_inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
132 {
133 	__wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
134 
135 	*sum = csum_fold(csum_add(tmp, (__force __wsum)to));
136 }
137 
138 /* Implements RFC 1624 (Incremental Internet Checksum)
139  * 3. Discussion states :
140  *     HC' = ~(~HC + ~m + m')
141  *  m : old value of a 16bit field
142  *  m' : new value of a 16bit field
143  */
csum_replace2(__sum16 * sum,__be16 old,__be16 new)144 static __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
145 {
146 	*sum = ~csum16_add(csum16_sub(~(*sum), old), new);
147 }
148 
csum_replace(__wsum * csum,__wsum old,__wsum new)149 static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
150 {
151 	*csum = csum_add(csum_sub(*csum, old), new);
152 }
153 
154 struct sk_buff;
155 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
156 			      __be32 from, __be32 to, bool pseudohdr);
157 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
158 			       const __be32 *from, const __be32 *to,
159 			       bool pseudohdr);
160 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
161 				     __wsum diff, bool pseudohdr);
162 
163 static __always_inline
inet_proto_csum_replace2(__sum16 * sum,struct sk_buff * skb,__be16 from,__be16 to,bool pseudohdr)164 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
165 			      __be16 from, __be16 to, bool pseudohdr)
166 {
167 	inet_proto_csum_replace4(sum, skb, (__force __be32)from,
168 				 (__force __be32)to, pseudohdr);
169 }
170 
remcsum_adjust(void * ptr,__wsum csum,int start,int offset)171 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum,
172 					     int start, int offset)
173 {
174 	__sum16 *psum = (__sum16 *)(ptr + offset);
175 	__wsum delta;
176 
177 	/* Subtract out checksum up to start */
178 	csum = csum_sub(csum, csum_partial(ptr, start, 0));
179 
180 	/* Set derived checksum in packet */
181 	delta = csum_sub((__force __wsum)csum_fold(csum),
182 			 (__force __wsum)*psum);
183 	*psum = csum_fold(csum);
184 
185 	return delta;
186 }
187 
remcsum_unadjust(__sum16 * psum,__wsum delta)188 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
189 {
190 	*psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
191 }
192 
wsum_negate(__wsum val)193 static __always_inline __wsum wsum_negate(__wsum val)
194 {
195 	return (__force __wsum)-((__force u32)val);
196 }
197 #endif
198