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 <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
  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
  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
  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
  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
  67 static __always_inline __wsum csum_sub(__wsum csum, __wsum addend)
  68 {
  69         return csum_add(csum, ~addend);
  70 }
  71
  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
  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
  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
  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
 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
 108 csum_block_sub(__wsum csum, __wsum csum2, int offset)
 109 {
 110         return csum_block_add(csum, ~csum2, offset);
 111 }
 112
 113 static __always_inline __wsum csum_unfold(__sum16 n)
 114 {
 115         return (__force __wsum)n;
 116 }
 117
 118 static __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
 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
 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  */
 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
 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 static inline unsigned short csum_from32to16(unsigned int sum)
 155 {
 156         sum += (sum >> 16) | (sum << 16);
 157         return (unsigned short)(sum >> 16);
 158 }
 159
 160 struct sk_buff;
 161 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 162                               __be32 from, __be32 to, bool pseudohdr);
 163 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 164                                const __be32 *from, const __be32 *to,
 165                                bool pseudohdr);
 166 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
 167                                      __wsum diff, bool pseudohdr);
 168
 169 static __always_inline
 170 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
 171                               __be16 from, __be16 to, bool pseudohdr)
 172 {
 173         inet_proto_csum_replace4(sum, skb, (__force __be32)from,
 174                                  (__force __be32)to, pseudohdr);
 175 }
 176
 177 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum,
 178                                              int start, int offset)
 179 {
 180         __sum16 *psum = (__sum16 *)(ptr + offset);
 181         __wsum delta;
 182
 183         /* Subtract out checksum up to start */
 184         csum = csum_sub(csum, csum_partial(ptr, start, 0));
 185
 186         /* Set derived checksum in packet */
 187         delta = csum_sub((__force __wsum)csum_fold(csum),
 188                          (__force __wsum)*psum);
 189         *psum = csum_fold(csum);
 190
 191         return delta;
 192 }
 193
 194 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
 195 {
 196         *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
 197 }
 198
 199 static __always_inline __wsum wsum_negate(__wsum val)
 200 {
 201         return (__force __wsum)-((__force u32)val);
 202 }
 203 #endif