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 __always_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 __always_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 __always_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 __always_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 __always_inline __wsum csum_sub(__wsum csum, __wsum addend) 66 { 67 return csum_add(csum, ~addend); 68 } 69 70 static __always_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 __always_inline __sum16 csum16_sub(__sum16 csum, __be16 addend) 79 { 80 return csum16_add(csum, ~addend); 81 } 82 83 #ifndef HAVE_ARCH_CSUM_SHIFT 84 static __always_inline __wsum csum_shift(__wsum sum, int offset) 85 { 86 /* rotate sum to align it with a 16b boundary */ 87 if (offset & 1) 88 return (__force __wsum)ror32((__force u32)sum, 8); 89 return sum; 90 } 91 #endif 92 93 static __always_inline __wsum 94 csum_block_add(__wsum csum, __wsum csum2, int offset) 95 { 96 return csum_add(csum, csum_shift(csum2, offset)); 97 } 98 99 static __always_inline __wsum 100 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) 101 { 102 return csum_block_add(csum, csum2, offset); 103 } 104 105 static __always_inline __wsum 106 csum_block_sub(__wsum csum, __wsum csum2, int offset) 107 { 108 return csum_block_add(csum, ~csum2, offset); 109 } 110 111 static __always_inline __wsum csum_unfold(__sum16 n) 112 { 113 return (__force __wsum)n; 114 } 115 116 static __always_inline 117 __wsum csum_partial_ext(const void *buff, int len, __wsum sum) 118 { 119 return csum_partial(buff, len, sum); 120 } 121 122 #define CSUM_MANGLED_0 ((__force __sum16)0xffff) 123 124 static __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff) 125 { 126 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum))); 127 } 128 129 static __always_inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to) 130 { 131 __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from); 132 133 *sum = csum_fold(csum_add(tmp, (__force __wsum)to)); 134 } 135 136 /* Implements RFC 1624 (Incremental Internet Checksum) 137 * 3. Discussion states : 138 * HC' = ~(~HC + ~m + m') 139 * m : old value of a 16bit field 140 * m' : new value of a 16bit field 141 */ 142 static __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new) 143 { 144 *sum = ~csum16_add(csum16_sub(~(*sum), old), new); 145 } 146 147 static inline void csum_replace(__wsum *csum, __wsum old, __wsum new) 148 { 149 *csum = csum_add(csum_sub(*csum, old), new); 150 } 151 152 struct sk_buff; 153 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, 154 __be32 from, __be32 to, bool pseudohdr); 155 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, 156 const __be32 *from, const __be32 *to, 157 bool pseudohdr); 158 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, 159 __wsum diff, bool pseudohdr); 160 161 static __always_inline 162 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb, 163 __be16 from, __be16 to, bool pseudohdr) 164 { 165 inet_proto_csum_replace4(sum, skb, (__force __be32)from, 166 (__force __be32)to, pseudohdr); 167 } 168 169 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum, 170 int start, int offset) 171 { 172 __sum16 *psum = (__sum16 *)(ptr + offset); 173 __wsum delta; 174 175 /* Subtract out checksum up to start */ 176 csum = csum_sub(csum, csum_partial(ptr, start, 0)); 177 178 /* Set derived checksum in packet */ 179 delta = csum_sub((__force __wsum)csum_fold(csum), 180 (__force __wsum)*psum); 181 *psum = csum_fold(csum); 182 183 return delta; 184 } 185 186 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta) 187 { 188 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum)); 189 } 190 191 static __always_inline __wsum wsum_negate(__wsum val) 192 { 193 return (__force __wsum)-((__force u32)val); 194 } 195 #endif 196