net/ipv6/ip6_checksum.c

   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, __u8 proto, __wsum csum)
  10 {
  11
  12         int carry;
  13         __u32 ulen;
  14         __u32 uproto;
  15         __u32 sum = (__force u32)csum;
  16
  17         sum += (__force u32)saddr->s6_addr32[0];
  18         carry = (sum < (__force u32)saddr->s6_addr32[0]);
  19         sum += carry;
  20
  21         sum += (__force u32)saddr->s6_addr32[1];
  22         carry = (sum < (__force u32)saddr->s6_addr32[1]);
  23         sum += carry;
  24
  25         sum += (__force u32)saddr->s6_addr32[2];
  26         carry = (sum < (__force u32)saddr->s6_addr32[2]);
  27         sum += carry;
  28
  29         sum += (__force u32)saddr->s6_addr32[3];
  30         carry = (sum < (__force u32)saddr->s6_addr32[3]);
  31         sum += carry;
  32
  33         sum += (__force u32)daddr->s6_addr32[0];
  34         carry = (sum < (__force u32)daddr->s6_addr32[0]);
  35         sum += carry;
  36
  37         sum += (__force u32)daddr->s6_addr32[1];
  38         carry = (sum < (__force u32)daddr->s6_addr32[1]);
  39         sum += carry;
  40
  41         sum += (__force u32)daddr->s6_addr32[2];
  42         carry = (sum < (__force u32)daddr->s6_addr32[2]);
  43         sum += carry;
  44
  45         sum += (__force u32)daddr->s6_addr32[3];
  46         carry = (sum < (__force u32)daddr->s6_addr32[3]);
  47         sum += carry;
  48
  49         ulen = (__force u32)htonl((__u32) len);
  50         sum += ulen;
  51         carry = (sum < ulen);
  52         sum += carry;
  53
  54         uproto = (__force u32)htonl(proto);
  55         sum += uproto;
  56         carry = (sum < uproto);
  57         sum += carry;
  58
  59         return csum_fold((__force __wsum)sum);
  60 }
  61 EXPORT_SYMBOL(csum_ipv6_magic);
  62 #endif
  63
  64 int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto)
  65 {
  66         int err;
  67
  68         UDP_SKB_CB(skb)->partial_cov = 0;
  69         UDP_SKB_CB(skb)->cscov = skb->len;
  70
  71         if (proto == IPPROTO_UDPLITE) {
  72                 err = udplite_checksum_init(skb, uh);
  73                 if (err)
  74                         return err;
  75         }
  76
  77         /* To support RFC 6936 (allow zero checksum in UDP/IPV6 for tunnels)
  78          * we accept a checksum of zero here. When we find the socket
  79          * for the UDP packet we'll check if that socket allows zero checksum
  80          * for IPv6 (set by socket option).
  81          */
  82         return skb_checksum_init_zero_check(skb, proto, uh->check,
  83                                            ip6_compute_pseudo);
  84 }
  85 EXPORT_SYMBOL(udp6_csum_init);
  86
  87 /* Function to set UDP checksum for an IPv6 UDP packet. This is intended
  88  * for the simple case like when setting the checksum for a UDP tunnel.
  89  */
  90 void udp6_set_csum(bool nocheck, struct sk_buff *skb,
  91                    const struct in6_addr *saddr,
  92                    const struct in6_addr *daddr, int len)
  93 {
  94         struct udphdr *uh = udp_hdr(skb);
  95
  96         if (nocheck)
  97                 uh->check = 0;
  98         else if (skb_is_gso(skb))
  99                 uh->check = ~udp_v6_check(len, saddr, daddr, 0);
 100         else if (skb->ip_summed == CHECKSUM_PARTIAL) {
 101                 uh->check = 0;
 102                 uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
 103                 if (uh->check == 0)
 104                         uh->check = CSUM_MANGLED_0;
 105         } else {
 106                 skb->ip_summed = CHECKSUM_PARTIAL;
 107                 skb->csum_start = skb_transport_header(skb) - skb->head;
 108                 skb->csum_offset = offsetof(struct udphdr, check);
 109                 uh->check = ~udp_v6_check(len, saddr, daddr, 0);
 110         }
 111 }
 112 EXPORT_SYMBOL(udp6_set_csum);