checksum.h

  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_sub(__wsum csum, __wsum csum2, int offset)
103{
104	return csum_block_add(csum, ~csum2, offset);
105}
106
107static __always_inline __wsum csum_unfold(__sum16 n)
108{
109	return (__force __wsum)n;
110}
111
112#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
113
114static __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
115{
116	*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
117}
118
119static __always_inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
120{
121	__wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
122
123	*sum = csum_fold(csum_add(tmp, (__force __wsum)to));
124}
125
126/* Implements RFC 1624 (Incremental Internet Checksum)
127 * 3. Discussion states :
128 *     HC' = ~(~HC + ~m + m')
129 *  m : old value of a 16bit field
130 *  m' : new value of a 16bit field
131 */
132static __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
133{
134	*sum = ~csum16_add(csum16_sub(~(*sum), old), new);
135}
136
137static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
138{
139	*csum = csum_add(csum_sub(*csum, old), new);
140}
141
142static inline unsigned short csum_from32to16(unsigned int sum)
143{
144	sum += (sum >> 16) | (sum << 16);
145	return (unsigned short)(sum >> 16);
146}
147
148struct sk_buff;
149void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
150			      __be32 from, __be32 to, bool pseudohdr);
151void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
152			       const __be32 *from, const __be32 *to,
153			       bool pseudohdr);
154void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
155				     __wsum diff, bool pseudohdr, bool ipv6);
156
157static __always_inline
158void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
159			      __be16 from, __be16 to, bool pseudohdr)
160{
161	inet_proto_csum_replace4(sum, skb, (__force __be32)from,
162				 (__force __be32)to, pseudohdr);
163}
164
165static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum,
166					     int start, int offset)
167{
168	__sum16 *psum = (__sum16 *)(ptr + offset);
169	__wsum delta;
170
171	/* Subtract out checksum up to start */
172	csum = csum_sub(csum, csum_partial(ptr, start, 0));
173
174	/* Set derived checksum in packet */
175	delta = csum_sub((__force __wsum)csum_fold(csum),
176			 (__force __wsum)*psum);
177	*psum = csum_fold(csum);
178
179	return delta;
180}
181
182static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
183{
184	*psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
185}
186
187static __always_inline __wsum wsum_negate(__wsum val)
188{
189	return (__force __wsum)-((__force u32)val);
190}
191#endif