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