include/net/udplite.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *      Definitions for the UDP-Lite (RFC 3828) code.
   4  */
   5 #ifndef _UDPLITE_H
   6 #define _UDPLITE_H
   7
   8 #include <net/ip6_checksum.h>
   9 #include <net/udp.h>
  10
  11 /* UDP-Lite socket options */
  12 #define UDPLITE_SEND_CSCOV   10 /* sender partial coverage (as sent)      */
  13 #define UDPLITE_RECV_CSCOV   11 /* receiver partial coverage (threshold ) */
  14
  15 extern struct proto             udplite_prot;
  16 extern struct udp_table         udplite_table;
  17
  18 /*
  19  *      Checksum computation is all in software, hence simpler getfrag.
  20  */
  21 static __inline__ int udplite_getfrag(void *from, char *to, int  offset,
  22                                       int len, int odd, struct sk_buff *skb)
  23 {
  24         struct msghdr *msg = from;
  25         return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;
  26 }
  27
  28 /*
  29  *      Checksumming routines
  30  */
  31 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
  32 {
  33         u16 cscov;
  34
  35         /* In UDPv4 a zero checksum means that the transmitter generated no
  36          * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
  37          * with a zero checksum field are illegal.                            */
  38         if (uh->check == 0) {
  39                 net_dbg_ratelimited("UDPLite: zeroed checksum field\n");
  40                 return 1;
  41         }
  42
  43         cscov = ntohs(uh->len);
  44
  45         if (cscov == 0)          /* Indicates that full coverage is required. */
  46                 ;
  47         else if (cscov < 8  || cscov > skb->len) {
  48                 /*
  49                  * Coverage length violates RFC 3828: log and discard silently.
  50                  */
  51                 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",
  52                                     cscov, skb->len);
  53                 return 1;
  54
  55         } else if (cscov < skb->len) {
  56                 UDP_SKB_CB(skb)->partial_cov = 1;
  57                 UDP_SKB_CB(skb)->cscov = cscov;
  58                 if (skb->ip_summed == CHECKSUM_COMPLETE)
  59                         skb->ip_summed = CHECKSUM_NONE;
  60                 skb->csum_valid = 0;
  61         }
  62
  63         return 0;
  64 }
  65
  66 /* Fast-path computation of checksum. Socket may not be locked. */
  67 static inline __wsum udplite_csum(struct sk_buff *skb)
  68 {
  69         const int off = skb_transport_offset(skb);
  70         const struct sock *sk = skb->sk;
  71         int len = skb->len - off;
  72
  73         if (udp_test_bit(UDPLITE_SEND_CC, sk)) {
  74                 u16 pcslen = READ_ONCE(udp_sk(sk)->pcslen);
  75
  76                 if (pcslen < len) {
  77                         if (pcslen > 0)
  78                                 len = pcslen;
  79                         udp_hdr(skb)->len = htons(pcslen);
  80                 }
  81         }
  82         skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
  83
  84         return skb_checksum(skb, off, len, 0);
  85 }
  86
  87 void udplite4_register(void);
  88 #endif  /* _UDPLITE_H */