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 } 68 69 return 0; 70 } 71 72 /* Slow-path computation of checksum. Socket is locked. */ 73 static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb) 74 { 75 const struct udp_sock *up = udp_sk(skb->sk); 76 int cscov = up->len; 77 __wsum csum = 0; 78 79 if (up->pcflag & UDPLITE_SEND_CC) { 80 /* 81 * Sender has set `partial coverage' option on UDP-Lite socket. 82 * The special case "up->pcslen == 0" signifies full coverage. 83 */ 84 if (up->pcslen < up->len) { 85 if (0 < up->pcslen) 86 cscov = up->pcslen; 87 udp_hdr(skb)->len = htons(up->pcslen); 88 } 89 /* 90 * NOTE: Causes for the error case `up->pcslen > up->len': 91 * (i) Application error (will not be penalized). 92 * (ii) Payload too big for send buffer: data is split 93 * into several packets, each with its own header. 94 * In this case (e.g. last segment), coverage may 95 * exceed packet length. 96 * Since packets with coverage length > packet length are 97 * illegal, we fall back to the defaults here. 98 */ 99 } 100 101 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 102 103 skb_queue_walk(&sk->sk_write_queue, skb) { 104 const int off = skb_transport_offset(skb); 105 const int len = skb->len - off; 106 107 csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum); 108 109 if ((cscov -= len) <= 0) 110 break; 111 } 112 return csum; 113 } 114 115 /* Fast-path computation of checksum. Socket may not be locked. */ 116 static inline __wsum udplite_csum(struct sk_buff *skb) 117 { 118 const struct udp_sock *up = udp_sk(skb->sk); 119 const int off = skb_transport_offset(skb); 120 int len = skb->len - off; 121 122 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 123 if (0 < up->pcslen) 124 len = up->pcslen; 125 udp_hdr(skb)->len = htons(up->pcslen); 126 } 127 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 128 129 return skb_checksum(skb, off, len, 0); 130 } 131 132 void udplite4_register(void); 133 int udplite_get_port(struct sock *sk, unsigned short snum, 134 int (*scmp)(const struct sock *, const struct sock *)); 135 #endif /* _UDPLITE_H */ 136