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
27static __always_inline
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
38static __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
50static __always_inline __wsum
51csum_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
59static __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
67static __always_inline __wsum csum_sub(__wsum csum, __wsum addend)
68{
69	return csum_add(csum, ~addend);
70}
71
72static __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
80static __always_inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
81{
82	return csum16_add(csum, ~addend);
83}
84
85#ifndef HAVE_ARCH_CSUM_SHIFT
86static __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
95static __always_inline __wsum
96csum_block_add(__wsum csum, __wsum csum2, int offset)
97{
98	return csum_add(csum, csum_shift(csum2, offset));
99}
100
101static __always_inline __wsum
102csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
103{
104	return csum_block_add(csum, csum2, offset);
105}
106
107static __always_inline __wsum
108csum_block_sub(__wsum csum, __wsum csum2, int offset)
109{
110	return csum_block_add(csum, ~csum2, offset);
111}
112
113static __always_inline __wsum csum_unfold(__sum16 n)
114{
115	return (__force __wsum)n;
116}
117
118static __always_inline
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
126static __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
127{
128	*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
129}
130
131static __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 */
144static __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
145{
146	*sum = ~csum16_add(csum16_sub(~(*sum), old), new);
147}
148
149static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
150{
151	*csum = csum_add(csum_sub(*csum, old), new);
152}
153
154struct sk_buff;
155void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
156			      __be32 from, __be32 to, bool pseudohdr);
157void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
158			       const __be32 *from, const __be32 *to,
159			       bool pseudohdr);
160void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
161				     __wsum diff, bool pseudohdr);
162
163static __always_inline
164void 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
171static __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
188static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
189{
190	*psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
191}
192
193static __always_inline __wsum wsum_negate(__wsum val)
194{
195	return (__force __wsum)-((__force u32)val);
196}
197#endif
198