net/ipv6/ip6_checksum.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <net/ip.h>
0003 #include <net/udp.h>
0004 #include <net/udplite.h>
0005 #include <asm/checksum.h>
0006
0007 #ifndef _HAVE_ARCH_IPV6_CSUM
0008 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
0009             const struct in6_addr *daddr,
0010             __u32 len, __u8 proto, __wsum csum)
0011 {
0012
0013     int carry;
0014     __u32 ulen;
0015     __u32 uproto;
0016     __u32 sum = (__force u32)csum;
0017
0018     sum += (__force u32)saddr->s6_addr32[0];
0019     carry = (sum < (__force u32)saddr->s6_addr32[0]);
0020     sum += carry;
0021
0022     sum += (__force u32)saddr->s6_addr32[1];
0023     carry = (sum < (__force u32)saddr->s6_addr32[1]);
0024     sum += carry;
0025
0026     sum += (__force u32)saddr->s6_addr32[2];
0027     carry = (sum < (__force u32)saddr->s6_addr32[2]);
0028     sum += carry;
0029
0030     sum += (__force u32)saddr->s6_addr32[3];
0031     carry = (sum < (__force u32)saddr->s6_addr32[3]);
0032     sum += carry;
0033
0034     sum += (__force u32)daddr->s6_addr32[0];
0035     carry = (sum < (__force u32)daddr->s6_addr32[0]);
0036     sum += carry;
0037
0038     sum += (__force u32)daddr->s6_addr32[1];
0039     carry = (sum < (__force u32)daddr->s6_addr32[1]);
0040     sum += carry;
0041
0042     sum += (__force u32)daddr->s6_addr32[2];
0043     carry = (sum < (__force u32)daddr->s6_addr32[2]);
0044     sum += carry;
0045
0046     sum += (__force u32)daddr->s6_addr32[3];
0047     carry = (sum < (__force u32)daddr->s6_addr32[3]);
0048     sum += carry;
0049
0050     ulen = (__force u32)htonl((__u32) len);
0051     sum += ulen;
0052     carry = (sum < ulen);
0053     sum += carry;
0054
0055     uproto = (__force u32)htonl(proto);
0056     sum += uproto;
0057     carry = (sum < uproto);
0058     sum += carry;
0059
0060     return csum_fold((__force __wsum)sum);
0061 }
0062 EXPORT_SYMBOL(csum_ipv6_magic);
0063 #endif
0064
0065 int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto)
0066 {
0067     int err;
0068
0069     UDP_SKB_CB(skb)->partial_cov = 0;
0070     UDP_SKB_CB(skb)->cscov = skb->len;
0071
0072     if (proto == IPPROTO_UDPLITE) {
0073         err = udplite_checksum_init(skb, uh);
0074         if (err)
0075             return err;
0076
0077         if (UDP_SKB_CB(skb)->partial_cov) {
0078             skb->csum = ip6_compute_pseudo(skb, proto);
0079             return 0;
0080         }
0081     }
0082
0083     /* To support RFC 6936 (allow zero checksum in UDP/IPV6 for tunnels)
0084      * we accept a checksum of zero here. When we find the socket
0085      * for the UDP packet we'll check if that socket allows zero checksum
0086      * for IPv6 (set by socket option).
0087      *
0088      * Note, we are only interested in != 0 or == 0, thus the
0089      * force to int.
0090      */
0091     err = (__force int)skb_checksum_init_zero_check(skb, proto, uh->check,
0092                             ip6_compute_pseudo);
0093     if (err)
0094         return err;
0095
0096     if (skb->ip_summed == CHECKSUM_COMPLETE && !skb->csum_valid) {
0097         /* If SW calculated the value, we know it's bad */
0098         if (skb->csum_complete_sw)
0099             return 1;
0100
0101         /* HW says the value is bad. Let's validate that.
0102          * skb->csum is no longer the full packet checksum,
0103          * so don't treat is as such.
0104          */
0105         skb_checksum_complete_unset(skb);
0106     }
0107
0108     return 0;
0109 }
0110 EXPORT_SYMBOL(udp6_csum_init);
0111
0112 /* Function to set UDP checksum for an IPv6 UDP packet. This is intended
0113  * for the simple case like when setting the checksum for a UDP tunnel.
0114  */
0115 void udp6_set_csum(bool nocheck, struct sk_buff *skb,
0116            const struct in6_addr *saddr,
0117            const struct in6_addr *daddr, int len)
0118 {
0119     struct udphdr *uh = udp_hdr(skb);
0120
0121     if (nocheck)
0122         uh->check = 0;
0123     else if (skb_is_gso(skb))
0124         uh->check = ~udp_v6_check(len, saddr, daddr, 0);
0125     else if (skb->ip_summed == CHECKSUM_PARTIAL) {
0126         uh->check = 0;
0127         uh->check = udp_v6_check(len, saddr, daddr, lco_csum(skb));
0128         if (uh->check == 0)
0129             uh->check = CSUM_MANGLED_0;
0130     } else {
0131         skb->ip_summed = CHECKSUM_PARTIAL;
0132         skb->csum_start = skb_transport_header(skb) - skb->head;
0133         skb->csum_offset = offsetof(struct udphdr, check);
0134         uh->check = ~udp_v6_check(len, saddr, daddr, 0);
0135     }
0136 }
0137 EXPORT_SYMBOL(udp6_set_csum);