1 /* SPDX-License-Identifier: GPL-2.0-or-later */
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.
7 * Checksumming functions for IP, TCP, UDP and so on
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.
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>
24 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
26 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
27 int len, __wsum sum, int *err_ptr)
29 if (copy_from_user(dst, src, len))
31 return csum_partial(dst, len, sum);
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)
39 sum = csum_partial(src, len, sum);
41 if (copy_to_user(dst, src, len) == 0)
46 return (__force __wsum)-1; /* invalid checksum */
50 #ifndef _HAVE_ARCH_CSUM_AND_COPY
52 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
54 memcpy(dst, src, len);
55 return csum_partial(dst, len, sum);
59 #ifndef HAVE_ARCH_CSUM_ADD
60 static inline __wsum csum_add(__wsum csum, __wsum addend)
62 u32 res = (__force u32)csum;
63 res += (__force u32)addend;
64 return (__force __wsum)(res + (res < (__force u32)addend));
68 static inline __wsum csum_sub(__wsum csum, __wsum addend)
70 return csum_add(csum, ~addend);
73 static inline __sum16 csum16_add(__sum16 csum, __be16 addend)
75 u16 res = (__force u16)csum;
77 res += (__force u16)addend;
78 return (__force __sum16)(res + (res < (__force u16)addend));
81 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
83 return csum16_add(csum, ~addend);
87 csum_block_add(__wsum csum, __wsum csum2, int offset)
89 u32 sum = (__force u32)csum2;
91 /* rotate sum to align it with a 16b boundary */
95 return csum_add(csum, (__force __wsum)sum);
99 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
101 return csum_block_add(csum, csum2, offset);
105 csum_block_sub(__wsum csum, __wsum csum2, int offset)
107 return csum_block_add(csum, ~csum2, offset);
110 static inline __wsum csum_unfold(__sum16 n)
112 return (__force __wsum)n;
115 static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
117 return csum_partial(buff, len, sum);
120 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
122 static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
124 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
127 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
129 __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
131 *sum = csum_fold(csum_add(tmp, (__force __wsum)to));
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
140 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
142 *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
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,
151 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
152 __wsum diff, bool pseudohdr);
154 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
155 __be16 from, __be16 to,
158 inet_proto_csum_replace4(sum, skb, (__force __be32)from,
159 (__force __be32)to, pseudohdr);
162 static inline __wsum remcsum_adjust(void *ptr, __wsum csum,
163 int start, int offset)
165 __sum16 *psum = (__sum16 *)(ptr + offset);
168 /* Subtract out checksum up to start */
169 csum = csum_sub(csum, csum_partial(ptr, start, 0));
171 /* Set derived checksum in packet */
172 delta = csum_sub((__force __wsum)csum_fold(csum),
173 (__force __wsum)*psum);
174 *psum = csum_fold(csum);
179 static inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
181 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));