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 struct sk_buff; 155 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, 156 __be32 from, __be32 to, bool pseudohdr); 157 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, 158 const __be32 *from, const __be32 *to, 159 bool pseudohdr); 160 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, 161 __wsum diff, bool pseudohdr); 162 163 static __always_inline 164 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb, 165 __be16 from, __be16 to, bool pseudohdr) 166 { 167 inet_proto_csum_replace4(sum, skb, (__force __be32)from, 168 (__force __be32)to, pseudohdr); 169 } 170 171 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum, 172 int start, int offset) 173 { 174 __sum16 *psum = (__sum16 *)(ptr + offset); 175 __wsum delta; 176 177 /* Subtract out checksum up to start */ 178 csum = csum_sub(csum, csum_partial(ptr, start, 0)); 179 180 /* Set derived checksum in packet */ 181 delta = csum_sub((__force __wsum)csum_fold(csum), 182 (__force __wsum)*psum); 183 *psum = csum_fold(csum); 184 185 return delta; 186 } 187 188 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta) 189 { 190 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum)); 191 } 192 193 static __always_inline __wsum wsum_negate(__wsum val) 194 { 195 return (__force __wsum)-((__force u32)val); 196 } 197 #endif 198