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
  25 static 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
  40 static __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
  57 static 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
  65 static inline __wsum csum_sub(__wsum csum, __wsum addend)
  66 {
  67         return csum_add(csum, ~addend);
  68 }
  69
  70 static 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
  78 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
  79 {
  80         return csum16_add(csum, ~addend);
  81 }
  82
  83 static inline __wsum
  84 csum_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
  95 static inline __wsum
  96 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
  97 {
  98         return csum_block_add(csum, csum2, offset);
  99 }
 100
 101 static inline __wsum
 102 csum_block_sub(__wsum csum, __wsum csum2, int offset)
 103 {
 104         return csum_block_add(csum, ~csum2, offset);
 105 }
 106
 107 static inline __wsum csum_unfold(__sum16 n)
 108 {
 109         return (__force __wsum)n;
 110 }
 111
 112 static 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
 119 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
 120 {
 121         *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
 122 }
 123
 124 static 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  */
 137 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
 138 {
 139         *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
 140 }
 141
 142 struct sk_buff;
 143 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 144                               __be32 from, __be32 to, bool pseudohdr);
 145 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 146                                const __be32 *from, const __be32 *to,
 147                                bool pseudohdr);
 148 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
 149                                      __wsum diff, bool pseudohdr);
 150
 151 static 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
 159 static 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
 176 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
 177 {
 178         *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));
 179 }
 180
 181 #endif