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 csum_shift(__wsum sum, int offset)
85 /* rotate sum to align it with a 16b boundary */
87 return (__force __wsum)ror32((__force u32)sum, 8);
91 static __always_inline __wsum
92 csum_block_add(__wsum csum, __wsum csum2, int offset)
94 return csum_add(csum, csum_shift(csum2, offset));
97 static __always_inline __wsum
98 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
100 return csum_block_add(csum, csum2, offset);
103 static __always_inline __wsum
104 csum_block_sub(__wsum csum, __wsum csum2, int offset)
106 return csum_block_add(csum, ~csum2, offset);
109 static __always_inline __wsum csum_unfold(__sum16 n)
111 return (__force __wsum)n;
114 static __always_inline
115 __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 __always_inline void csum_replace_by_diff(__sum16 *sum, __wsum diff)
124 *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
127 static __always_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 __always_inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
142 *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
145 static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
147 *csum = csum_add(csum_sub(*csum, old), new);
151 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
152 __be32 from, __be32 to, bool pseudohdr);
153 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
154 const __be32 *from, const __be32 *to,
156 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
157 __wsum diff, bool pseudohdr);
159 static __always_inline
160 void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
161 __be16 from, __be16 to, bool pseudohdr)
163 inet_proto_csum_replace4(sum, skb, (__force __be32)from,
164 (__force __be32)to, pseudohdr);
167 static __always_inline __wsum remcsum_adjust(void *ptr, __wsum csum,
168 int start, int offset)
170 __sum16 *psum = (__sum16 *)(ptr + offset);
173 /* Subtract out checksum up to start */
174 csum = csum_sub(csum, csum_partial(ptr, start, 0));
176 /* Set derived checksum in packet */
177 delta = csum_sub((__force __wsum)csum_fold(csum),
178 (__force __wsum)*psum);
179 *psum = csum_fold(csum);
184 static __always_inline void remcsum_unadjust(__sum16 *psum, __wsum delta)
186 *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum));