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Linux/net/ipv6/ip6_checksum.c

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  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);
138 

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