xref: /openbmc/linux/net/ipv6/ip6_checksum.c (revision 8851b9f1)
1 #include <net/ip.h>
2 #include <net/udp.h>
3 #include <net/udplite.h>
4 #include <asm/checksum.h>
5 
6 #ifndef _HAVE_ARCH_IPV6_CSUM
7 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
8 			const struct in6_addr *daddr,
9 			__u32 len, unsigned short proto,
10 			__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 
78 	if (uh->check == 0) {
79 		/* RFC 2460 section 8.1 says that we SHOULD log
80 		   this error. Well, it is reasonable.
81 		 */
82 		LIMIT_NETDEBUG(KERN_INFO "IPv6: udp checksum is 0\n");
83 		return 1;
84 	}
85 	if (skb->ip_summed == CHECKSUM_COMPLETE &&
86 	    !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr,
87 			     skb->len, proto, skb->csum))
88 		skb->ip_summed = CHECKSUM_UNNECESSARY;
89 
90 	if (!skb_csum_unnecessary(skb))
91 		skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
92 							 &ipv6_hdr(skb)->daddr,
93 							 skb->len, proto, 0));
94 
95 	return 0;
96 }
97 EXPORT_SYMBOL(udp6_csum_init);
98