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 (copy_from_user(dst, src, len)) 30 *err_ptr = -EFAULT; 31 return csum_partial(dst, len, sum); 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, __wsum sum, int *err_ptr) 38 { 39 sum = csum_partial(src, len, sum); 40 41 if (copy_to_user(dst, src, len) == 0) 42 return sum; 43 if (len) 44 *err_ptr = -EFAULT; 45 46 return (__force __wsum)-1; /* invalid checksum */ 47 } 48 #endif 49 50 #ifndef _HAVE_ARCH_CSUM_AND_COPY 51 static inline __wsum 52 csum_partial_copy_nocheck(const void *src, void *dst, int len) 53 { 54 memcpy(dst, src, len); 55 return csum_partial(dst, len, 0); 56 } 57 #endif 58 59 #ifndef HAVE_ARCH_CSUM_ADD 60 static inline __wsum csum_add(__wsum csum, __wsum addend) 61 { 62 u32 res = (__force u32)csum; 63 res += (__force u32)addend; 64 return (__force __wsum)(res + (res < (__force u32)addend)); 65 } 66 #endif 67 68 static inline __wsum csum_sub(__wsum csum, __wsum addend) 69 { 70 return csum_add(csum, ~addend); 71 } 72 73 static inline __sum16 csum16_add(__sum16 csum, __be16 addend) 74 { 75 u16 res = (__force u16)csum; 76 77 res += (__force u16)addend; 78 return (__force __sum16)(res + (res < (__force u16)addend)); 79 } 80 81 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend) 82 { 83 return csum16_add(csum, ~addend); 84 } 85 86 static inline __wsum 87 csum_block_add(__wsum csum, __wsum csum2, int offset) 88 { 89 u32 sum = (__force u32)csum2; 90 91 /* rotate sum to align it with a 16b boundary */ 92 if (offset & 1) 93 sum = ror32(sum, 8); 94 95 return csum_add(csum, (__force __wsum)sum); 96 } 97 98 static inline __wsum 99 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) 100 { 101 return csum_block_add(csum, csum2, offset); 102 } 103 104 static inline __wsum 105 csum_block_sub(__wsum csum, __wsum csum2, int offset) 106 { 107 return csum_block_add(csum, ~csum2, offset); 108 } 109 110 static inline __wsum csum_unfold(__sum16 n) 111 { 112 return (__force __wsum)n; 113 } 114 115 static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum) 116 { 117 return csum_partial(buff, len, sum); 118 } 119 120 #define CSUM_MANGLED_0 ((__force __sum16)0xffff) 121 122 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff) 123 { 124 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum))); 125 } 126 127 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to) 128 { 129 __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from); 130 131 *sum = csum_fold(csum_add(tmp, (__force __wsum)to)); 132 } 133 134 /* Implements RFC 1624 (Incremental Internet Checksum) 135 * 3. Discussion states : 136 * HC' = ~(~HC + ~m + m') 137 * m : old value of a 16bit field 138 * m' : new value of a 16bit field 139 */ 140 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new) 141 { 142 *sum = ~csum16_add(csum16_sub(~(*sum), old), new); 143 } 144 145 struct sk_buff; 146 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, 147 __be32 from, __be32 to, bool pseudohdr); 148 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, 149 const __be32 *from, const __be32 *to, 150 bool pseudohdr); 151 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, 152 __wsum diff, bool pseudohdr); 153 154 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb, 155 __be16 from, __be16 to, 156 bool pseudohdr) 157 { 158 inet_proto_csum_replace4(sum, skb, (__force __be32)from, 159 (__force __be32)to, pseudohdr); 160 } 161 162 static inline __wsum remcsum_adjust(void *ptr, __wsum csum, 163 int start, int offset) 164 { 165 __sum16 *psum = (__sum16 *)(ptr + offset); 166 __wsum delta; 167 168 /* Subtract out checksum up to start */ 169 csum = csum_sub(csum, csum_partial(ptr, start, 0)); 170 171 /* Set derived checksum in packet */ 172 delta = csum_sub((__force __wsum)csum_fold(csum), 173 (__force __wsum)*psum); 174 *psum = csum_fold(csum); 175 176 return delta; 177 } 178 179 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta) 180 { 181 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum)); 182 } 183 184 #endif 185