// 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#include <net/icmp.h>
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#include <net/sock.h>
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#include <net/inet_sock.h>
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#include <net/netfilter/nf_socket.h>
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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#include <net/netfilter/nf_conntrack.h>
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#endif
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static int
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extract_icmp4_fields(const struct sk_buff *skb, u8 *protocol,
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__be32 *raddr, __be32 *laddr,
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__be16 *rport, __be16 *lport)
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{
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unsigned int outside_hdrlen = ip_hdrlen(skb);
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struct iphdr *inside_iph, _inside_iph;
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struct icmphdr *icmph, _icmph;
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__be16 *ports, _ports[2];
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icmph = skb_header_pointer(skb, outside_hdrlen,
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sizeof(_icmph), &_icmph);
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if (icmph == NULL)
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return 1;
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if (!icmp_is_err(icmph->type))
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return 1;
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inside_iph = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr),
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sizeof(_inside_iph), &_inside_iph);
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if (inside_iph == NULL)
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return 1;
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if (inside_iph->protocol != IPPROTO_TCP &&
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inside_iph->protocol != IPPROTO_UDP)
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return 1;
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ports = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr) +
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(inside_iph->ihl << 2),
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sizeof(_ports), &_ports);
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if (ports == NULL)
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return 1;
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/* the inside IP packet is the one quoted from our side, thus
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* its saddr is the local address */
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*protocol = inside_iph->protocol;
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*laddr = inside_iph->saddr;
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*lport = ports[0];
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*raddr = inside_iph->daddr;
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*rport = ports[1];
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return 0;
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}
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static struct sock *
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nf_socket_get_sock_v4(struct net *net, struct sk_buff *skb, const int doff,
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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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{
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switch (protocol) {
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case IPPROTO_TCP:
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return inet_lookup(net, &tcp_hashinfo, skb, doff,
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saddr, sport, daddr, dport,
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in->ifindex);
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case IPPROTO_UDP:
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return udp4_lib_lookup(net, saddr, sport, daddr, dport,
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in->ifindex);
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}
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return NULL;
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}
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struct sock *nf_sk_lookup_slow_v4(struct net *net, const struct sk_buff *skb,
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const struct net_device *indev)
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{
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__be32 daddr, saddr;
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__be16 dport, sport;
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const struct iphdr *iph = ip_hdr(skb);
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struct sk_buff *data_skb = NULL;
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u8 protocol;
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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enum ip_conntrack_info ctinfo;
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struct nf_conn const *ct;
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#endif
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int doff = 0;
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if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
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struct tcphdr _hdr;
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struct udphdr *hp;
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hp = skb_header_pointer(skb, ip_hdrlen(skb),
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iph->protocol == IPPROTO_UDP ?
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sizeof(*hp) : sizeof(_hdr), &_hdr);
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if (hp == NULL)
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return NULL;
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protocol = iph->protocol;
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saddr = iph->saddr;
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sport = hp->source;
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daddr = iph->daddr;
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dport = hp->dest;
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data_skb = (struct sk_buff *)skb;
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doff = iph->protocol == IPPROTO_TCP ?
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ip_hdrlen(skb) + __tcp_hdrlen((struct tcphdr *)hp) :
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ip_hdrlen(skb) + sizeof(*hp);
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} else if (iph->protocol == IPPROTO_ICMP) {
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if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
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&sport, &dport))
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return NULL;
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} else {
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return NULL;
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}
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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/* Do the lookup with the original socket address in
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* case this is a reply packet of an established
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* SNAT-ted connection.
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*/
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ct = nf_ct_get(skb, &ctinfo);
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if (ct &&
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((iph->protocol != IPPROTO_ICMP &&
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ctinfo == IP_CT_ESTABLISHED_REPLY) ||
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(iph->protocol == IPPROTO_ICMP &&
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ctinfo == IP_CT_RELATED_REPLY)) &&
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(ct->status & IPS_SRC_NAT_DONE)) {
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daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
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dport = (iph->protocol == IPPROTO_TCP) ?
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
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}
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#endif
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return nf_socket_get_sock_v4(net, data_skb, doff, protocol, saddr,
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daddr, sport, dport, indev);
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}
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EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v4);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
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MODULE_DESCRIPTION("Netfilter IPv4 socket lookup infrastructure");
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