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) 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 36 static __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 48 static inline __wsum 49 csum_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 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 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 91 static inline __wsum 92 csum_block_add(__wsum csum, __wsum csum2, int offset) 93 { 94 return csum_add(csum, csum_shift(csum2, offset)); 95 } 96 97 static inline __wsum 98 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) 99 { 100 return csum_block_add(csum, csum2, offset); 101 } 102 103 static inline __wsum 104 csum_block_sub(__wsum csum, __wsum csum2, int offset) 105 { 106 return csum_block_add(csum, ~csum2, offset); 107 } 108 109 static inline __wsum csum_unfold(__sum16 n) 110 { 111 return (__force __wsum)n; 112 } 113 114 static 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) 120 121 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff) 122 { 123 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum))); 124 } 125 126 static 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 */ 139 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new) 140 { 141 *sum = ~csum16_add(csum16_sub(~(*sum), old), new); 142 } 143 144 struct sk_buff; 145 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, 146 __be32 from, __be32 to, bool pseudohdr); 147 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, 148 const __be32 *from, const __be32 *to, 149 bool pseudohdr); 150 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, 151 __wsum diff, bool pseudohdr); 152 153 static 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 } 160 161 static 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 } 177 178 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta) 179 { 180 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum)); 181 } 182 183 #endif 184