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 }
62 EXPORT_SYMBOL(csum_ipv6_magic);
63 #endif
64
65 int 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 }
110 EXPORT_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 */
115 void 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 }
137 EXPORT_SYMBOL(udp6_set_csum);
138
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