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, __wsum sum, int *err_ptr)
  28{
  29        if (access_ok(src, len))
  30                return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
  31
  32        if (len)
  33                *err_ptr = -EFAULT;
  34
  35        return sum;
  36}
  37#endif
  38
  39#ifndef HAVE_CSUM_COPY_USER
  40static __inline__ __wsum csum_and_copy_to_user
  41(const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
  42{
  43        sum = csum_partial(src, len, sum);
  44
  45        if (access_ok(dst, len)) {
  46                if (copy_to_user(dst, src, len) == 0)
  47                        return sum;
  48        }
  49        if (len)
  50                *err_ptr = -EFAULT;
  51
  52        return (__force __wsum)-1; /* invalid checksum */
  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
  84csum_block_add(__wsum csum, __wsum csum2, int offset)
  85{
  86        u32 sum = (__force u32)csum2;
  87
  88        /* rotate sum to align it with a 16b boundary */
  89        if (offset & 1)
  90                sum = ror32(sum, 8);
  91
  92        return csum_add(csum, (__force __wsum)sum);
  93}
  94
  95static inline __wsum
  96csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
  97{
  98        return csum_block_add(csum, csum2, offset);
  99}
 100
 101static inline __wsum
 102csum_block_sub(__wsum csum, __wsum csum2, int offset)
 103{
 104        return csum_block_add(csum, ~csum2, offset);
 105}
 106
 107static inline __wsum csum_unfold(__sum16 n)
 108{
 109        return (__force __wsum)n;
 110}
 111
 112static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
 113{
 114        return csum_partial(buff, len, sum);
 115}
 116
 117#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
 118
 119static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
 120{
 121        *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
 122}
 123
 124static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
 125{
 126        __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
 127
 128        *sum = csum_fold(csum_add(tmp, (__force __wsum)to));
 129}
 130
 131/* Implements RFC 1624 (Incremental Internet Checksum)
 132 * 3. Discussion states :
 133 *     HC' = ~(~HC + ~m + m')
 134 *  m : old value of a 16bit field
 135 *  m' : new value of a 16bit field
 136 */
 137static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
 138{
 139        *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
 140}
 141
 142struct sk_buff;
 143void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 144                              __be32 from, __be32 to, bool pseudohdr);
 145void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 146                               const __be32 *from, const __be32 *to,
 147                               bool pseudohdr);
 148void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
 149                                     __wsum diff, bool pseudohdr);
 150
 151static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
 152                                            __be16 from, __be16 to,
 153                                            bool pseudohdr)
 154{
 155        inet_proto_csum_replace4(sum, skb, (__force __be32)from,
 156                                 (__force __be32)to, pseudohdr);
 157}
 158
 159static inline __wsum remcsum_adjust(void *ptr, __wsum csum,
 160                                    int start, int offset)
 161{
 162        __sum16 *psum = (__sum16 *)(ptr + offset);
 163        __wsum delta;
 164
 165        /* Subtract out checksum up to start */
 166        csum = csum_sub(csum, csum_partial(ptr, start, 0));
 167
 168        /* Set derived checksum in packet */
 169        delta = csum_sub((__force __wsum)csum_fold(csum),
 170                         (__force __wsum)*psum);
 171        *psum = csum_fold(csum);
 172
 173        return delta;
 174}
 175
 176static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
 177{
 178        *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
 179}
 180
 181#endif
 182