1 /* 2 * Copyright (C) 2007-2008 BalaBit IT Ltd. 3 * Author: Krisztian Kovacs 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 */ 10 11 #include <net/netfilter/nf_tproxy.h> 12 #include <linux/module.h> 13 #include <linux/skbuff.h> 14 #include <net/sock.h> 15 #include <net/inet_sock.h> 16 #include <linux/ip.h> 17 #include <net/checksum.h> 18 #include <net/udp.h> 19 #include <net/tcp.h> 20 #include <linux/inetdevice.h> 21 22 struct sock * 23 nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb, 24 __be32 laddr, __be16 lport, struct sock *sk) 25 { 26 const struct iphdr *iph = ip_hdr(skb); 27 struct tcphdr _hdr, *hp; 28 29 hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); 30 if (hp == NULL) { 31 inet_twsk_put(inet_twsk(sk)); 32 return NULL; 33 } 34 35 if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { 36 /* SYN to a TIME_WAIT socket, we'd rather redirect it 37 * to a listener socket if there's one */ 38 struct sock *sk2; 39 40 sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol, 41 iph->saddr, laddr ? laddr : iph->daddr, 42 hp->source, lport ? lport : hp->dest, 43 skb->dev, NF_TPROXY_LOOKUP_LISTENER); 44 if (sk2) { 45 inet_twsk_deschedule_put(inet_twsk(sk)); 46 sk = sk2; 47 } 48 } 49 50 return sk; 51 } 52 EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4); 53 54 __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr) 55 { 56 struct in_device *indev; 57 __be32 laddr; 58 59 if (user_laddr) 60 return user_laddr; 61 62 laddr = 0; 63 indev = __in_dev_get_rcu(skb->dev); 64 for_primary_ifa(indev) { 65 laddr = ifa->ifa_local; 66 break; 67 } endfor_ifa(indev); 68 69 return laddr ? laddr : daddr; 70 } 71 EXPORT_SYMBOL_GPL(nf_tproxy_laddr4); 72 73 struct sock * 74 nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, 75 const u8 protocol, 76 const __be32 saddr, const __be32 daddr, 77 const __be16 sport, const __be16 dport, 78 const struct net_device *in, 79 const enum nf_tproxy_lookup_t lookup_type) 80 { 81 struct sock *sk; 82 83 switch (protocol) { 84 case IPPROTO_TCP: { 85 struct tcphdr _hdr, *hp; 86 87 hp = skb_header_pointer(skb, ip_hdrlen(skb), 88 sizeof(struct tcphdr), &_hdr); 89 if (hp == NULL) 90 return NULL; 91 92 switch (lookup_type) { 93 case NF_TPROXY_LOOKUP_LISTENER: 94 sk = inet_lookup_listener(net, &tcp_hashinfo, skb, 95 ip_hdrlen(skb) + 96 __tcp_hdrlen(hp), 97 saddr, sport, 98 daddr, dport, 99 in->ifindex, 0); 100 101 if (sk && !refcount_inc_not_zero(&sk->sk_refcnt)) 102 sk = NULL; 103 /* NOTE: we return listeners even if bound to 104 * 0.0.0.0, those are filtered out in 105 * xt_socket, since xt_TPROXY needs 0 bound 106 * listeners too 107 */ 108 break; 109 case NF_TPROXY_LOOKUP_ESTABLISHED: 110 sk = inet_lookup_established(net, &tcp_hashinfo, 111 saddr, sport, daddr, dport, 112 in->ifindex); 113 break; 114 default: 115 BUG(); 116 } 117 break; 118 } 119 case IPPROTO_UDP: 120 sk = udp4_lib_lookup(net, saddr, sport, daddr, dport, 121 in->ifindex); 122 if (sk) { 123 int connected = (sk->sk_state == TCP_ESTABLISHED); 124 int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0); 125 126 /* NOTE: we return listeners even if bound to 127 * 0.0.0.0, those are filtered out in 128 * xt_socket, since xt_TPROXY needs 0 bound 129 * listeners too 130 */ 131 if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && 132 (!connected || wildcard)) || 133 (lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) { 134 sock_put(sk); 135 sk = NULL; 136 } 137 } 138 break; 139 default: 140 WARN_ON(1); 141 sk = NULL; 142 } 143 144 pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n", 145 protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk); 146 147 return sk; 148 } 149 EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4); 150 151 MODULE_LICENSE("GPL"); 152 MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); 153 MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support"); 154