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
15extern struct proto udplite_prot;
16extern struct udp_table udplite_table;
17
18/*
19 * Checksum computation is all in software, hence simpler getfrag.
20 */
21static __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(addr: to, bytes: len, i: &msg->msg_iter) ? 0 : -EFAULT;
26}
27
28/*
29 * Checksumming routines
30 */
31static 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. */
67static 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, offset: off, len, csum: 0);
85}
86
87void udplite4_register(void);
88#endif /* _UDPLITE_H */
89