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
25 static __always_inline
26 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
29 if (copy_from_user(dst, src, len))
31 return csum_partial(dst, len, ~0U);
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)
39 __wsum sum = csum_partial(src, len, ~0U);
41 if (copy_to_user(dst, src, len) == 0)
47 #ifndef _HAVE_ARCH_CSUM_AND_COPY
48 static __always_inline __wsum
49 csum_partial_copy_nocheck(const void *src, void *dst, int len)
51 memcpy(dst, src, len);
52 return csum_partial(dst, len, 0);
56 #ifndef HAVE_ARCH_CSUM_ADD
57 static __always_inline __wsum csum_add(__wsum csum, __wsum addend)
59 u32 res = (__force u32)csum;
60 res += (__force u32)addend;
61 return (__force __wsum)(res + (res < (__force u32)addend));
65 static __always_inline __wsum csum_sub(__wsum csum, __wsum addend)
67 return csum_add(csum, ~addend);
70 static __always_inline __sum16 csum16_add(__sum16 csum, __be16 addend)
72 u16 res = (__force u16)csum;
74 res += (__force u16)addend;
75 return (__force __sum16)(res + (res < (__force u16)addend));
78 static __always_inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
80 return csum16_add(csum, ~addend);
83 static __always_inline __wsum
84 csum_block_add(__wsum csum, __wsum csum2, int offset)
86 u32 sum = (__force u32)csum2;
88 /* rotate sum to align it with a 16b boundary */
92 return csum_add(csum, (__force __wsum)sum);
95 static __always_inline __wsum
96 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
98 return csum_block_add(csum, csum2, offset);
101 static __always_inline __wsum
102 csum_block_sub(__wsum csum, __wsum csum2, int offset)
104 return csum_block_add(csum, ~csum2, offset);
107 static __always_inline __wsum csum_unfold(__sum16 n)
109 return (__force __wsum)n;
112 static __always_inline
113 __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
115 return csum_partial(buff, len, sum);
118 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
120 static __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
122 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
125 static __always_inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
127 __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from);
129 *sum = csum_fold(csum_add(tmp, (__force __wsum)to));
132 /* Implements RFC 1624 (Incremental Internet Checksum)
133 * 3. Discussion states :
134 * HC' = ~(~HC + ~m + m')
135 * m : old value of a 16bit field
136 * m' : new value of a 16bit field
138 static __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
140 *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
143 static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
145 *csum = csum_add(csum_sub(*csum, old), new);
149 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
150 __be32 from, __be32 to, bool pseudohdr);
151 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
152 const __be32 *from, const __be32 *to,
154 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
155 __wsum diff, bool pseudohdr);
157 static __always_inline
158 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
159 __be16 from, __be16 to, bool pseudohdr)
161 inet_proto_csum_replace4(sum, skb, (__force __be32)from,
162 (__force __be32)to, pseudohdr);
165 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum,
166 int start, int offset)
168 __sum16 *psum = (__sum16 *)(ptr + offset);
171 /* Subtract out checksum up to start */
172 csum = csum_sub(csum, csum_partial(ptr, start, 0));
174 /* Set derived checksum in packet */
175 delta = csum_sub((__force __wsum)csum_fold(csum),
176 (__force __wsum)*psum);
177 *psum = csum_fold(csum);
182 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
184 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));