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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (C) 2007-2008 BalaBit IT Ltd.
- * Author: Krisztian Kovacs
- */
- #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)
- {
- const struct in_ifaddr *ifa;
- struct in_device *indev;
- __be32 laddr;
- if (user_laddr)
- return user_laddr;
- laddr = 0;
- indev = __in_dev_get_rcu(skb->dev);
- in_dev_for_each_ifa_rcu(ifa, indev) {
- if (ifa->ifa_flags & IFA_F_SECONDARY)
- continue;
- laddr = ifa->ifa_local;
- break;
- }
- 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");
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