net/ipv6/ip6_checksum.c

   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);