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