LXR linux/include/net/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 <linux/uaccess.h>
  22#include <asm/checksum.h>
  23
  24#ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  25static inline
  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
  36static __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
  48static inline __wsum
  49csum_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
  57static 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
  65static inline __wsum csum_sub(__wsum csum, __wsum addend)
  66{
  67        return csum_add(csum, ~addend);
  68}
  69
  70static 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
  78static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
  79{
  80        return csum16_add(csum, ~addend);
  81}
  82
  83static 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
  91static inline __wsum
  92csum_block_add(__wsum csum, __wsum csum2, int offset)
  93{
  94        return csum_add(csum, csum_shift(csum2, offset));
  95}
  96
  97static inline __wsum
  98csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
  99{
 100        return csum_block_add(csum, csum2, offset);
 101}
 102
 103static inline __wsum
 104csum_block_sub(__wsum csum, __wsum csum2, int offset)
 105{
 106        return csum_block_add(csum, ~csum2, offset);
 107}
 108
 109static inline __wsum csum_unfold(__sum16 n)
 110{
 111        return (__force __wsum)n;
 112}
 113
 114static 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
 121static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
 122{
 123        *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
 124}
 125
 126static 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 */
 139static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
 140{
 141        *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
 142}
 143
 144struct sk_buff;
 145void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 146                              __be32 from, __be32 to, bool pseudohdr);
 147void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 148                               const __be32 *from, const __be32 *to,
 149                               bool pseudohdr);
 150void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
 151                                     __wsum diff, bool pseudohdr);
 152
 153static 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
 161static 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
 178static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
 179{
 180        *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
 181}
 182
 183#endif
 184