| /* |
| * Copyright (C) 2007-2008 BalaBit IT Ltd. |
| * Author: Krisztian Kovacs |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| |
| #include <net/netfilter/nf_tproxy.h> |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <net/sock.h> |
| #include <net/inet_sock.h> |
| #include <linux/ip.h> |
| #include <net/checksum.h> |
| #include <net/udp.h> |
| #include <net/tcp.h> |
| #include <linux/inetdevice.h> |
| |
| struct sock * |
| nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb, |
| __be32 laddr, __be16 lport, struct sock *sk) |
| { |
| const struct iphdr *iph = ip_hdr(skb); |
| struct tcphdr _hdr, *hp; |
| |
| hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); |
| if (hp == NULL) { |
| inet_twsk_put(inet_twsk(sk)); |
| return NULL; |
| } |
| |
| if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { |
| /* SYN to a TIME_WAIT socket, we'd rather redirect it |
| * to a listener socket if there's one */ |
| struct sock *sk2; |
| |
| sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol, |
| iph->saddr, laddr ? laddr : iph->daddr, |
| hp->source, lport ? lport : hp->dest, |
| skb->dev, NF_TPROXY_LOOKUP_LISTENER); |
| if (sk2) { |
| inet_twsk_deschedule_put(inet_twsk(sk)); |
| sk = sk2; |
| } |
| } |
| |
| return sk; |
| } |
| EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4); |
| |
| __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr) |
| { |
| struct in_device *indev; |
| __be32 laddr; |
| |
| if (user_laddr) |
| return user_laddr; |
| |
| laddr = 0; |
| indev = __in_dev_get_rcu(skb->dev); |
| for_primary_ifa(indev) { |
| laddr = ifa->ifa_local; |
| break; |
| } endfor_ifa(indev); |
| |
| return laddr ? laddr : daddr; |
| } |
| EXPORT_SYMBOL_GPL(nf_tproxy_laddr4); |
| |
| struct sock * |
| nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, |
| const u8 protocol, |
| const __be32 saddr, const __be32 daddr, |
| const __be16 sport, const __be16 dport, |
| const struct net_device *in, |
| const enum nf_tproxy_lookup_t lookup_type) |
| { |
| struct sock *sk; |
| |
| switch (protocol) { |
| case IPPROTO_TCP: { |
| struct tcphdr _hdr, *hp; |
| |
| hp = skb_header_pointer(skb, ip_hdrlen(skb), |
| sizeof(struct tcphdr), &_hdr); |
| if (hp == NULL) |
| return NULL; |
| |
| switch (lookup_type) { |
| case NF_TPROXY_LOOKUP_LISTENER: |
| sk = inet_lookup_listener(net, &tcp_hashinfo, skb, |
| ip_hdrlen(skb) + |
| __tcp_hdrlen(hp), |
| saddr, sport, |
| daddr, dport, |
| in->ifindex, 0); |
| |
| if (sk && !refcount_inc_not_zero(&sk->sk_refcnt)) |
| sk = NULL; |
| /* NOTE: we return listeners even if bound to |
| * 0.0.0.0, those are filtered out in |
| * xt_socket, since xt_TPROXY needs 0 bound |
| * listeners too |
| */ |
| break; |
| case NF_TPROXY_LOOKUP_ESTABLISHED: |
| sk = inet_lookup_established(net, &tcp_hashinfo, |
| saddr, sport, daddr, dport, |
| in->ifindex); |
| break; |
| default: |
| BUG(); |
| } |
| break; |
| } |
| case IPPROTO_UDP: |
| sk = udp4_lib_lookup(net, saddr, sport, daddr, dport, |
| in->ifindex); |
| if (sk) { |
| int connected = (sk->sk_state == TCP_ESTABLISHED); |
| int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0); |
| |
| /* NOTE: we return listeners even if bound to |
| * 0.0.0.0, those are filtered out in |
| * xt_socket, since xt_TPROXY needs 0 bound |
| * listeners too |
| */ |
| if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && |
| (!connected || wildcard)) || |
| (lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) { |
| sock_put(sk); |
| sk = NULL; |
| } |
| } |
| break; |
| default: |
| WARN_ON(1); |
| sk = NULL; |
| } |
| |
| pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n", |
| protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk); |
| |
| return sk; |
| } |
| EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); |
| MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support"); |