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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(to, len, &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, off, len, 0);
85}
86
87void udplite4_register(void);
88#endif /* _UDPLITE_H */
1/*
2 * Definitions for the UDP-Lite (RFC 3828) code.
3 */
4#ifndef _UDPLITE_H
5#define _UDPLITE_H
6
7#include <net/ip6_checksum.h>
8
9/* UDP-Lite socket options */
10#define UDPLITE_SEND_CSCOV 10 /* sender partial coverage (as sent) */
11#define UDPLITE_RECV_CSCOV 11 /* receiver partial coverage (threshold ) */
12
13extern struct proto udplite_prot;
14extern struct udp_table udplite_table;
15
16/*
17 * Checksum computation is all in software, hence simpler getfrag.
18 */
19static __inline__ int udplite_getfrag(void *from, char *to, int offset,
20 int len, int odd, struct sk_buff *skb)
21{
22 struct msghdr *msg = from;
23 return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;
24}
25
26/* Designate sk as UDP-Lite socket */
27static inline int udplite_sk_init(struct sock *sk)
28{
29 udp_sk(sk)->pcflag = UDPLITE_BIT;
30 sk->sk_destruct = udp_destruct_sock;
31 return 0;
32}
33
34/*
35 * Checksumming routines
36 */
37static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
38{
39 u16 cscov;
40
41 /* In UDPv4 a zero checksum means that the transmitter generated no
42 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
43 * with a zero checksum field are illegal. */
44 if (uh->check == 0) {
45 net_dbg_ratelimited("UDPLite: zeroed checksum field\n");
46 return 1;
47 }
48
49 cscov = ntohs(uh->len);
50
51 if (cscov == 0) /* Indicates that full coverage is required. */
52 ;
53 else if (cscov < 8 || cscov > skb->len) {
54 /*
55 * Coverage length violates RFC 3828: log and discard silently.
56 */
57 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",
58 cscov, skb->len);
59 return 1;
60
61 } else if (cscov < skb->len) {
62 UDP_SKB_CB(skb)->partial_cov = 1;
63 UDP_SKB_CB(skb)->cscov = cscov;
64 if (skb->ip_summed == CHECKSUM_COMPLETE)
65 skb->ip_summed = CHECKSUM_NONE;
66 }
67
68 return 0;
69}
70
71/* Slow-path computation of checksum. Socket is locked. */
72static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
73{
74 const struct udp_sock *up = udp_sk(skb->sk);
75 int cscov = up->len;
76 __wsum csum = 0;
77
78 if (up->pcflag & UDPLITE_SEND_CC) {
79 /*
80 * Sender has set `partial coverage' option on UDP-Lite socket.
81 * The special case "up->pcslen == 0" signifies full coverage.
82 */
83 if (up->pcslen < up->len) {
84 if (0 < up->pcslen)
85 cscov = up->pcslen;
86 udp_hdr(skb)->len = htons(up->pcslen);
87 }
88 /*
89 * NOTE: Causes for the error case `up->pcslen > up->len':
90 * (i) Application error (will not be penalized).
91 * (ii) Payload too big for send buffer: data is split
92 * into several packets, each with its own header.
93 * In this case (e.g. last segment), coverage may
94 * exceed packet length.
95 * Since packets with coverage length > packet length are
96 * illegal, we fall back to the defaults here.
97 */
98 }
99
100 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
101
102 skb_queue_walk(&sk->sk_write_queue, skb) {
103 const int off = skb_transport_offset(skb);
104 const int len = skb->len - off;
105
106 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
107
108 if ((cscov -= len) <= 0)
109 break;
110 }
111 return csum;
112}
113
114/* Fast-path computation of checksum. Socket may not be locked. */
115static inline __wsum udplite_csum(struct sk_buff *skb)
116{
117 const struct udp_sock *up = udp_sk(skb->sk);
118 const int off = skb_transport_offset(skb);
119 int len = skb->len - off;
120
121 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
122 if (0 < up->pcslen)
123 len = up->pcslen;
124 udp_hdr(skb)->len = htons(up->pcslen);
125 }
126 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */
127
128 return skb_checksum(skb, off, len, 0);
129}
130
131void udplite4_register(void);
132int udplite_get_port(struct sock *sk, unsigned short snum,
133 int (*scmp)(const struct sock *, const struct sock *));
134#endif /* _UDPLITE_H */