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 182