// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2007-2008 BalaBit IT Ltd.
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* Author: Krisztian Kovacs
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*/
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#include <net/netfilter/nf_tproxy.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/inet_sock.h>
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#include <linux/ip.h>
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#include <net/checksum.h>
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#include <net/udp.h>
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#include <net/tcp.h>
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#include <linux/inetdevice.h>
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struct sock *
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nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
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__be32 laddr, __be16 lport, struct sock *sk)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct tcphdr _hdr, *hp;
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hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
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if (hp == NULL) {
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inet_twsk_put(inet_twsk(sk));
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return NULL;
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}
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if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
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/* SYN to a TIME_WAIT socket, we'd rather redirect it
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* to a listener socket if there's one */
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struct sock *sk2;
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sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
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iph->saddr, laddr ? laddr : iph->daddr,
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hp->source, lport ? lport : hp->dest,
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skb->dev, NF_TPROXY_LOOKUP_LISTENER);
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if (sk2) {
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inet_twsk_deschedule_put(inet_twsk(sk));
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sk = sk2;
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}
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}
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return sk;
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}
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EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4);
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__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
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{
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const struct in_ifaddr *ifa;
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struct in_device *indev;
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__be32 laddr;
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if (user_laddr)
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return user_laddr;
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laddr = 0;
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indev = __in_dev_get_rcu(skb->dev);
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in_dev_for_each_ifa_rcu(ifa, indev) {
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if (ifa->ifa_flags & IFA_F_SECONDARY)
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continue;
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laddr = ifa->ifa_local;
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break;
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}
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return laddr ? laddr : daddr;
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}
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EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);
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struct sock *
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nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
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const u8 protocol,
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const __be32 saddr, const __be32 daddr,
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const __be16 sport, const __be16 dport,
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const struct net_device *in,
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const enum nf_tproxy_lookup_t lookup_type)
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{
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struct sock *sk;
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switch (protocol) {
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case IPPROTO_TCP: {
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struct tcphdr _hdr, *hp;
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hp = skb_header_pointer(skb, ip_hdrlen(skb),
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sizeof(struct tcphdr), &_hdr);
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if (hp == NULL)
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return NULL;
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switch (lookup_type) {
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case NF_TPROXY_LOOKUP_LISTENER:
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sk = inet_lookup_listener(net, &tcp_hashinfo, skb,
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ip_hdrlen(skb) +
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__tcp_hdrlen(hp),
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saddr, sport,
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daddr, dport,
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in->ifindex, 0);
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if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
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sk = NULL;
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/* NOTE: we return listeners even if bound to
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* 0.0.0.0, those are filtered out in
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* xt_socket, since xt_TPROXY needs 0 bound
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* listeners too
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*/
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break;
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case NF_TPROXY_LOOKUP_ESTABLISHED:
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sk = inet_lookup_established(net, &tcp_hashinfo,
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saddr, sport, daddr, dport,
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in->ifindex);
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break;
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default:
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BUG();
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}
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break;
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}
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case IPPROTO_UDP:
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sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
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in->ifindex);
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if (sk) {
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int connected = (sk->sk_state == TCP_ESTABLISHED);
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int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0);
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/* NOTE: we return listeners even if bound to
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* 0.0.0.0, those are filtered out in
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* xt_socket, since xt_TPROXY needs 0 bound
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* listeners too
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*/
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if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED &&
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(!connected || wildcard)) ||
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(lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) {
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sock_put(sk);
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sk = NULL;
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}
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}
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break;
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default:
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WARN_ON(1);
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sk = NULL;
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}
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pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
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protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
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return sk;
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}
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EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
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MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support");
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