// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2007-2008 BalaBit IT Ltd.
* Author: Krisztian Kovacs
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/sock.h>
#include <net/inet_sock.h>
#include <net/netfilter/nf_socket.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack.h>
#endif
static int
extract_icmp4_fields(const struct sk_buff *skb, u8 *protocol,
__be32 *raddr, __be32 *laddr,
__be16 *rport, __be16 *lport)
{
unsigned int outside_hdrlen = ip_hdrlen(skb);
struct iphdr *inside_iph, _inside_iph;
struct icmphdr *icmph, _icmph;
__be16 *ports, _ports[2];
icmph = skb_header_pointer(skb, outside_hdrlen,
sizeof(_icmph), &_icmph);
if (icmph == NULL)
return 1;
if (!icmp_is_err(icmph->type))
return 1;
inside_iph = skb_header_pointer(skb, outside_hdrlen +
sizeof(struct icmphdr),
sizeof(_inside_iph), &_inside_iph);
if (inside_iph == NULL)
return 1;
if (inside_iph->protocol != IPPROTO_TCP &&
inside_iph->protocol != IPPROTO_UDP)
return 1;
ports = skb_header_pointer(skb, outside_hdrlen +
sizeof(struct icmphdr) +
(inside_iph->ihl << 2),
sizeof(_ports), &_ports);
if (ports == NULL)
return 1;
/* the inside IP packet is the one quoted from our side, thus
* its saddr is the local address */
*protocol = inside_iph->protocol;
*laddr = inside_iph->saddr;
*lport = ports[0];
*raddr = inside_iph->daddr;
*rport = ports[1];
return 0;
}
static struct sock *
nf_socket_get_sock_v4(struct net *net, struct sk_buff *skb, const int doff,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in)
{
switch (protocol) {
case IPPROTO_TCP:
return inet_lookup(net, net->ipv4.tcp_death_row.hashinfo,
skb, doff, saddr, sport, daddr, dport,
in->ifindex);
case IPPROTO_UDP:
return udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
}
return NULL;
}
struct sock *nf_sk_lookup_slow_v4(struct net *net, const struct sk_buff *skb,
const struct net_device *indev)
{
__be32 daddr, saddr;
__be16 dport, sport;
const struct iphdr *iph = ip_hdr(skb);
struct sk_buff *data_skb = NULL;
u8 protocol;
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
enum ip_conntrack_info ctinfo;
struct nf_conn const *ct;
#endif
int doff = 0;
if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
struct tcphdr _hdr;
struct udphdr *hp;
hp = skb_header_pointer(skb, ip_hdrlen(skb),
iph->protocol == IPPROTO_UDP ?
sizeof(*hp) : sizeof(_hdr), &_hdr);
if (hp == NULL)
return NULL;
protocol = iph->protocol;
saddr = iph->saddr;
sport = hp->source;
daddr = iph->daddr;
dport = hp->dest;
data_skb = (struct sk_buff *)skb;
doff = iph->protocol == IPPROTO_TCP ?
ip_hdrlen(skb) + __tcp_hdrlen((struct tcphdr *)hp) :
ip_hdrlen(skb) + sizeof(*hp);
} else if (iph->protocol == IPPROTO_ICMP) {
if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
&sport, &dport))
return NULL;
} else {
return NULL;
}
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
/* Do the lookup with the original socket address in
* case this is a reply packet of an established
* SNAT-ted connection.
*/
ct = nf_ct_get(skb, &ctinfo);
if (ct &&
((iph->protocol != IPPROTO_ICMP &&
ctinfo == IP_CT_ESTABLISHED_REPLY) ||
(iph->protocol == IPPROTO_ICMP &&
ctinfo == IP_CT_RELATED_REPLY)) &&
(ct->status & IPS_SRC_NAT_DONE)) {
daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
dport = (iph->protocol == IPPROTO_TCP) ?
ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
}
#endif
return nf_socket_get_sock_v4(net, data_skb, doff, protocol, saddr,
daddr, sport, dport, indev);
}
EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v4);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
MODULE_DESCRIPTION("Netfilter IPv4 socket lookup infrastructure");