Line data    Source code

       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             : 
      10             : /* UDP-Lite socket options */
      11             : #define UDPLITE_SEND_CSCOV   10 /* sender partial coverage (as sent)      */
      12             : #define UDPLITE_RECV_CSCOV   11 /* receiver partial coverage (threshold ) */
      13             : 
      14             : extern struct proto             udplite_prot;
      15             : extern struct udp_table         udplite_table;
      16             : 
      17             : /*
      18             :  *      Checksum computation is all in software, hence simpler getfrag.
      19             :  */
      20           0 : static __inline__ int udplite_getfrag(void *from, char *to, int  offset,
      21             :                                       int len, int odd, struct sk_buff *skb)
      22             : {
      23           0 :         struct msghdr *msg = from;
      24           0 :         return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;
      25             : }
      26             : 
      27             : /* Designate sk as UDP-Lite socket */
      28           0 : static inline int udplite_sk_init(struct sock *sk)
      29             : {
      30           0 :         udp_init_sock(sk);
      31           0 :         udp_sk(sk)->pcflag = UDPLITE_BIT;
      32           0 :         return 0;
      33             : }
      34             : 
      35             : /*
      36             :  *      Checksumming routines
      37             :  */
      38           0 : static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
      39             : {
      40           0 :         u16 cscov;
      41             : 
      42             :         /* In UDPv4 a zero checksum means that the transmitter generated no
      43             :          * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
      44             :          * with a zero checksum field are illegal.                            */
      45           0 :         if (uh->check == 0) {
      46             :                 net_dbg_ratelimited("UDPLite: zeroed checksum field\n");
      47             :                 return 1;
      48             :         }
      49             : 
      50           0 :         cscov = ntohs(uh->len);
      51             : 
      52           0 :         if (cscov == 0)          /* Indicates that full coverage is required. */
      53             :                 ;
      54           0 :         else if (cscov < 8  || cscov > skb->len) {
      55             :                 /*
      56             :                  * Coverage length violates RFC 3828: log and discard silently.
      57             :                  */
      58             :                 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",
      59             :                                     cscov, skb->len);
      60             :                 return 1;
      61             : 
      62           0 :         } else if (cscov < skb->len) {
      63           0 :                 UDP_SKB_CB(skb)->partial_cov = 1;
      64           0 :                 UDP_SKB_CB(skb)->cscov = cscov;
      65           0 :                 if (skb->ip_summed == CHECKSUM_COMPLETE)
      66           0 :                         skb->ip_summed = CHECKSUM_NONE;
      67           0 :                 skb->csum_valid = 0;
      68             :         }
      69             : 
      70             :         return 0;
      71             : }
      72             : 
      73             : /* Slow-path computation of checksum. Socket is locked. */
      74             : static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
      75             : {
      76             :         const struct udp_sock *up = udp_sk(skb->sk);
      77             :         int cscov = up->len;
      78             :         __wsum csum = 0;
      79             : 
      80             :         if (up->pcflag & UDPLITE_SEND_CC) {
      81             :                 /*
      82             :                  * Sender has set `partial coverage' option on UDP-Lite socket.
      83             :                  * The special case "up->pcslen == 0" signifies full coverage.
      84             :                  */
      85             :                 if (up->pcslen < up->len) {
      86             :                         if (0 < up->pcslen)
      87             :                                 cscov = up->pcslen;
      88             :                         udp_hdr(skb)->len = htons(up->pcslen);
      89             :                 }
      90             :                 /*
      91             :                  * NOTE: Causes for the error case  `up->pcslen > up->len':
      92             :                  *        (i)  Application error (will not be penalized).
      93             :                  *       (ii)  Payload too big for send buffer: data is split
      94             :                  *             into several packets, each with its own header.
      95             :                  *             In this case (e.g. last segment), coverage may
      96             :                  *             exceed packet length.
      97             :                  *       Since packets with coverage length > packet length are
      98             :                  *       illegal, we fall back to the defaults here.
      99             :                  */
     100             :         }
     101             : 
     102             :         skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
     103             : 
     104             :         skb_queue_walk(&sk->sk_write_queue, skb) {
     105             :                 const int off = skb_transport_offset(skb);
     106             :                 const int len = skb->len - off;
     107             : 
     108             :                 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
     109             : 
     110             :                 if ((cscov -= len) <= 0)
     111             :                         break;
     112             :         }
     113             :         return csum;
     114             : }
     115             : 
     116             : /* Fast-path computation of checksum. Socket may not be locked. */
     117           0 : static inline __wsum udplite_csum(struct sk_buff *skb)
     118             : {
     119           0 :         const struct udp_sock *up = udp_sk(skb->sk);
     120           0 :         const int off = skb_transport_offset(skb);
     121           0 :         int len = skb->len - off;
     122             : 
     123           0 :         if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
     124           0 :                 if (0 < up->pcslen)
     125           0 :                         len = up->pcslen;
     126           0 :                 udp_hdr(skb)->len = htons(up->pcslen);
     127             :         }
     128           0 :         skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
     129             : 
     130           0 :         return skb_checksum(skb, off, len, 0);
     131             : }
     132             : 
     133             : void udplite4_register(void);
     134             : int udplite_get_port(struct sock *sk, unsigned short snum,
     135             :                      int (*scmp)(const struct sock *, const struct sock *));
     136             : #endif  /* _UDPLITE_H */