1// SPDX-License-Identifier: GPL-2.0
2#include <net/ip.h>
3#include <net/udp.h>
4#include <net/udplite.h>
5#include <asm/checksum.h>
6
7#ifndef _HAVE_ARCH_IPV6_CSUM
8__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
9			const struct in6_addr *daddr,
10			__u32 len, __u8 proto, __wsum csum)
11{
12
13	int carry;
14	__u32 ulen;
15	__u32 uproto;
16	__u32 sum = (__force u32)csum;
17
18	sum += (__force u32)saddr->s6_addr32[0];
19	carry = (sum < (__force u32)saddr->s6_addr32[0]);
20	sum += carry;
21
22	sum += (__force u32)saddr->s6_addr32[1];
23	carry = (sum < (__force u32)saddr->s6_addr32[1]);
24	sum += carry;
25
26	sum += (__force u32)saddr->s6_addr32[2];
27	carry = (sum < (__force u32)saddr->s6_addr32[2]);
28	sum += carry;
29
30	sum += (__force u32)saddr->s6_addr32[3];
31	carry = (sum < (__force u32)saddr->s6_addr32[3]);
32	sum += carry;
33
34	sum += (__force u32)daddr->s6_addr32[0];
35	carry = (sum < (__force u32)daddr->s6_addr32[0]);
36	sum += carry;
37
38	sum += (__force u32)daddr->s6_addr32[1];
39	carry = (sum < (__force u32)daddr->s6_addr32[1]);
40	sum += carry;
41
42	sum += (__force u32)daddr->s6_addr32[2];
43	carry = (sum < (__force u32)daddr->s6_addr32[2]);
44	sum += carry;
45
46	sum += (__force u32)daddr->s6_addr32[3];
47	carry = (sum < (__force u32)daddr->s6_addr32[3]);
48	sum += carry;
49
50	ulen = (__force u32)htonl((__u32) len);
51	sum += ulen;
52	carry = (sum < ulen);
53	sum += carry;
54
55	uproto = (__force u32)htonl(proto);
56	sum += uproto;
57	carry = (sum < uproto);
58	sum += carry;
59
60	return csum_fold((__force __wsum)sum);
61}
62EXPORT_SYMBOL(csum_ipv6_magic);
63#endif
64
65int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto)
66{
67	int err;
68
69	UDP_SKB_CB(skb)->partial_cov = 0;
70	UDP_SKB_CB(skb)->cscov = skb->len;
71
72	if (proto == IPPROTO_UDPLITE) {
73		err = udplite_checksum_init(skb, uh);
74		if (err)
75			return err;
76
77		if (UDP_SKB_CB(skb)->partial_cov) {
78			skb->csum = ip6_compute_pseudo(skb, proto);
79			return 0;
80		}
81	}
82
83	/* To support RFC 6936 (allow zero checksum in UDP/IPV6 for tunnels)
84	 * we accept a checksum of zero here. When we find the socket
85	 * for the UDP packet we'll check if that socket allows zero checksum
86	 * for IPv6 (set by socket option).
87	 *
88	 * Note, we are only interested in != 0 or == 0, thus the
89	 * force to int.
90	 */
91	err = (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
92							ip6_compute_pseudo);
93	if (err)
94		return err;
95
96	if (skb->ip_summed == CHECKSUM_COMPLETE && !skb->csum_valid) {
97		/* If SW calculated the value, we know it's bad */
98		if (skb->csum_complete_sw)
99			return 1;
100
101		/* HW says the value is bad. Let's validate that.
102		 * skb->csum is no longer the full packet checksum,
103		 * so don't treat is as such.
104		 */
105		skb_checksum_complete_unset(skb);
106	}
107
108	return 0;
109}
110EXPORT_SYMBOL(udp6_csum_init);
111
112/* Function to set UDP checksum for an IPv6 UDP packet. This is intended
113 * for the simple case like when setting the checksum for a UDP tunnel.
114 */
115void udp6_set_csum(bool nocheck, struct sk_buff *skb,
116		   const struct in6_addr *saddr,
117		   const struct in6_addr *daddr, int len)
118{
119	struct udphdr *uh = udp_hdr(skb);
120
121	if (nocheck)
122		uh->check = 0;
123	else if (skb_is_gso(skb))
124		uh->check = ~udp_v6_check(len, saddr, daddr, 0);
125	else if (skb->ip_summed == CHECKSUM_PARTIAL) {
126		uh->check = 0;
127		uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
128		if (uh->check == 0)
129			uh->check = CSUM_MANGLED_0;
130	} else {
131		skb->ip_summed = CHECKSUM_PARTIAL;
132		skb->csum_start = skb_transport_header(skb) - skb->head;
133		skb->csum_offset = offsetof(struct udphdr, check);
134		uh->check = ~udp_v6_check(len, saddr, daddr, 0);
135	}
136}
137EXPORT_SYMBOL(udp6_set_csum);
138