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 15 extern struct proto udplite_prot; 16 extern struct udp_table udplite_table; 17 18 /* 19 * Checksum computation is all in software, hence simpler getfrag. 20 */ 21 static __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 /* Designate sk as UDP-Lite socket */ 29 static inline int udplite_sk_init(struct sock *sk) 30 { 31 udp_init_sock(sk); 32 udp_sk(sk)->pcflag = UDPLITE_BIT; 33 return 0; 34 } 35 36 /* 37 * Checksumming routines 38 */ 39 static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 40 { 41 u16 cscov; 42 43 /* In UDPv4 a zero checksum means that the transmitter generated no 44 * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets 45 * with a zero checksum field are illegal. */ 46 if (uh->check == 0) { 47 net_dbg_ratelimited("UDPLite: zeroed checksum field\n"); 48 return 1; 49 } 50 51 cscov = ntohs(uh->len); 52 53 if (cscov == 0) /* Indicates that full coverage is required. */ 54 ; 55 else if (cscov < 8 || cscov > skb->len) { 56 /* 57 * Coverage length violates RFC 3828: log and discard silently. 58 */ 59 net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n", 60 cscov, skb->len); 61 return 1; 62 63 } else if (cscov < skb->len) { 64 UDP_SKB_CB(skb)->partial_cov = 1; 65 UDP_SKB_CB(skb)->cscov = cscov; 66 if (skb->ip_summed == CHECKSUM_COMPLETE) 67 skb->ip_summed = CHECKSUM_NONE; 68 skb->csum_valid = 0; 69 } 70 71 return 0; 72 } 73 74 /* Fast-path computation of checksum. Socket may not be locked. */ 75 static inline __wsum udplite_csum(struct sk_buff *skb) 76 { 77 const struct udp_sock *up = udp_sk(skb->sk); 78 const int off = skb_transport_offset(skb); 79 int len = skb->len - off; 80 81 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 82 if (0 < up->pcslen) 83 len = up->pcslen; 84 udp_hdr(skb)->len = htons(up->pcslen); 85 } 86 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 87 88 return skb_checksum(skb, off, len, 0); 89 } 90 91 void udplite4_register(void); 92 int udplite_get_port(struct sock *sk, unsigned short snum, 93 int (*scmp)(const struct sock *, const struct sock *)); 94 #endif /* _UDPLITE_H */ 95