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 */
89
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