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                 if (UDP_SKB_CB(skb)->partial_cov) {
  77                         skb->csum = ip6_compute_pseudo(skb, proto);
  78                         return 0;
  79                 }
  80         }
  81
  82         /* To support RFC 6936 (allow zero checksum in UDP/IPV6 for tunnels)
  83          * we accept a checksum of zero here. When we find the socket
  84          * for the UDP packet we'll check if that socket allows zero checksum
  85          * for IPv6 (set by socket option).
  86          *
  87          * Note, we are only interested in != 0 or == 0, thus the
  88          * force to int.
  89          */
  90         err = (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
  91                                                         ip6_compute_pseudo);
  92         if (err)
  93                 return err;
  94
  95         if (skb->ip_summed == CHECKSUM_COMPLETE && !skb->csum_valid) {
  96                 /* If SW calculated the value, we know it's bad */
  97                 if (skb->csum_complete_sw)
  98                         return 1;
  99
 100                 /* HW says the value is bad. Let's validate that.
 101                  * skb->csum is no longer the full packet checksum,
 102                  * so don't treat is as such.
 103                  */
 104                 skb_checksum_complete_unset(skb);
 105         }
 106
 107         return 0;
 108 }
 109 EXPORT_SYMBOL(udp6_csum_init);
 110
 111 /* Function to set UDP checksum for an IPv6 UDP packet. This is intended
 112  * for the simple case like when setting the checksum for a UDP tunnel.
 113  */
 114 void udp6_set_csum(bool nocheck, struct sk_buff *skb,
 115                    const struct in6_addr *saddr,
 116                    const struct in6_addr *daddr, int len)
 117 {
 118         struct udphdr *uh = udp_hdr(skb);
 119
 120         if (nocheck)
 121                 uh->check = 0;
 122         else if (skb_is_gso(skb))
 123                 uh->check = ~udp_v6_check(len, saddr, daddr, 0);
 124         else if (skb->ip_summed == CHECKSUM_PARTIAL) {
 125                 uh->check = 0;
 126                 uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
 127                 if (uh->check == 0)
 128                         uh->check = CSUM_MANGLED_0;
 129         } else {
 130                 skb->ip_summed = CHECKSUM_PARTIAL;
 131                 skb->csum_start = skb_transport_header(skb) - skb->head;
 132                 skb->csum_offset = offsetof(struct udphdr, check);
 133                 uh->check = ~udp_v6_check(len, saddr, daddr, 0);
 134         }
 135 }
 136 EXPORT_SYMBOL(udp6_set_csum);