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, 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         /* To support RFC 6936 (allow zero checksum in UDP/IPV6 for tunnels)
  79          * we accept a checksum of zero here. When we find the socket
  80          * for the UDP packet we'll check if that socket allows zero checksum
  81          * for IPv6 (set by socket option).
  82          */
  83         return skb_checksum_init_zero_check(skb, proto, uh->check,
  84                                            ip6_compute_pseudo);
  85 }
  86 EXPORT_SYMBOL(udp6_csum_init);
  87
  88 /* Function to set UDP checksum for an IPv6 UDP packet. This is intended
  89  * for the simple case like when setting the checksum for a UDP tunnel.
  90  */
  91 void udp6_set_csum(bool nocheck, struct sk_buff *skb,
  92                    const struct in6_addr *saddr,
  93                    const struct in6_addr *daddr, int len)
  94 {
  95         struct udphdr *uh = udp_hdr(skb);
  96
  97         if (nocheck)
  98                 uh->check = 0;
  99         else if (skb_is_gso(skb))
 100                 uh->check = ~udp_v6_check(len, saddr, daddr, 0);
 101         else if (skb_dst(skb) && skb_dst(skb)->dev &&
 102                  (skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
 103
 104                 BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
 105
 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         } else {
 111                 __wsum csum;
 112
 113                 BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL);
 114
 115                 uh->check = 0;
 116                 csum = skb_checksum(skb, 0, len, 0);
 117                 uh->check = udp_v6_check(len, saddr, daddr, csum);
 118                 if (uh->check == 0)
 119                         uh->check = CSUM_MANGLED_0;
 120
 121                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 122         }
 123 }
 124 EXPORT_SYMBOL(udp6_set_csum);