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 */ 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 /* Designate sk as UDP-Lite socket */ 28 static inline int udplite_sk_init(struct sock *sk) 29 { 30 udp_init_sock(sk); 31 udp_sk(sk)->pcflag = UDPLITE_BIT; 32 return 0; 33 } 34 35 /* 36 * Checksumming routines 37 */ 38 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 39 { 40 u16 cscov; 41 42 /* In UDPv4 a zero checksum means that the transmitter generated no 43 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets 44 * with a zero checksum field are illegal. */ 45 if (uh->check == 0) { 46 net_dbg_ratelimited("UDPLite: zeroed checksum field\n"); 47 return 1; 48 } 49 50 cscov = ntohs(uh->len); 51 52 if (cscov == 0) /* Indicates that full coverage is required. */ 53 ; 54 else if (cscov < 8 || cscov > skb->len) { 55 /* 56 * Coverage length violates RFC 3828: log and discard silently. 57 */ 58 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n", 59 cscov, skb->len); 60 return 1; 61 62 } else if (cscov < skb->len) { 63 UDP_SKB_CB(skb)->partial_cov = 1; 64 UDP_SKB_CB(skb)->cscov = cscov; 65 if (skb->ip_summed == CHECKSUM_COMPLETE) 66 skb->ip_summed = CHECKSUM_NONE; 67 skb->csum_valid = 0; 68 } 69 70 return 0; 71 } 72 73 /* Fast-path computation of checksum. Socket may not be locked. */ 74 static inline __wsum udplite_csum(struct sk_buff *skb) 75 { 76 const struct udp_sock *up = udp_sk(skb->sk); 77 const int off = skb_transport_offset(skb); 78 int len = skb->len - off; 79 80 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 81 if (0 < up->pcslen) 82 len = up->pcslen; 83 udp_hdr(skb)->len = htons(up->pcslen); 84 } 85 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 86 87 return skb_checksum(skb, off, len, 0); 88 } 89 90 void udplite4_register(void); 91 int udplite_get_port(struct sock *sk, unsigned short snum, 92 int (*scmp)(const struct sock *, const struct sock *)); 93 #endif /* _UDPLITE_H */ 94