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 /* 29 * Checksumming routines 30 */ 31 static 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. */ 67 static inline __wsum udplite_csum(struct sk_buff *skb) 68 { 69 const struct udp_sock *up = udp_sk(skb->sk); 70 const int off = skb_transport_offset(skb); 71 int len = skb->len - off; 72 73 if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) { 74 if (0 < up->pcslen) 75 len = up->pcslen; 76 udp_hdr(skb)->len = htons(up->pcslen); 77 } 78 skb->ip_summed = CHECKSUM_NONE; /* no HW support for checksumming */ 79 80 return skb_checksum(skb, off, len, 0); 81 } 82 83 void udplite4_register(void); 84 #endif /* _UDPLITE_H */ 85