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