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 */ 89