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 14extern struct proto udplite_prot; 15extern struct udp_table udplite_table; 16 17/* 18 * Checksum computation is all in software, hence simpler getfrag. 19 */ 20static __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 */ 30static 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. */ 66static 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. */ 109static 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 125void udplite4_register(void); 126int udplite_get_port(struct sock *sk, unsigned short snum, 127 int (*scmp)(const struct sock *, const struct sock *)); 128#endif /* _UDPLITE_H */ 129