/* * Transparent proxy support for Linux/iptables * * 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. * */#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt#include <linux/module.h>#include <linux/skbuff.h>#include <linux/netfilter/x_tables.h>#include <linux/netfilter_ipv4/ip_tables.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_tproxy_core.h>#include <net/netfilter/ipv4/nf_defrag_ipv4.h> #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)#define XT_SOCKET_HAVE_IPV6 1#include <linux/netfilter_ipv6/ip6_tables.h>#include <net/netfilter/ipv6/nf_defrag_ipv6.h>#endif #include <linux/netfilter/xt_socket.h> #if IS_ENABLED(CONFIG_NF_CONNTRACK)#define XT_SOCKET_HAVE_CONNTRACK 1#include <net/netfilter/nf_conntrack.h>#endif static voidxt_socket_put_sk(struct sock *sk){	if (sk->sk_state == TCP_TIME_WAIT)		inet_twsk_put(inet_twsk(sk));	else		sock_put(sk);} static intextract_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; 	switch (icmph->type) {	case ICMP_DEST_UNREACH:	case ICMP_SOURCE_QUENCH:	case ICMP_REDIRECT:	case ICMP_TIME_EXCEEDED:	case ICMP_PARAMETERPROB:		break;	default:		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 boolsocket_match(const struct sk_buff *skb, struct xt_action_param *par,	     const struct xt_socket_mtinfo1 *info){	const struct iphdr *iph = ip_hdr(skb);	struct udphdr _hdr, *hp = NULL;	struct sock *sk;	__be32 daddr, saddr;	__be16 dport, sport;	u8 protocol;#ifdef XT_SOCKET_HAVE_CONNTRACK	struct nf_conn const *ct;	enum ip_conntrack_info ctinfo;#endif 	if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {		hp = skb_header_pointer(skb, ip_hdrlen(skb),					sizeof(_hdr), &_hdr);		if (hp == NULL)			return false; 		protocol = iph->protocol;		saddr = iph->saddr;		sport = hp->source;		daddr = iph->daddr;		dport = hp->dest; 	} else if (iph->protocol == IPPROTO_ICMP) {		if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,					&sport, &dport))			return false;	} else {		return false;	} #ifdef XT_SOCKET_HAVE_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 && !nf_ct_is_untracked(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 	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,				   saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);	if (sk != NULL) {		bool wildcard;		bool transparent = true; 		/* Ignore sockets listening on INADDR_ANY */		wildcard = (sk->sk_state != TCP_TIME_WAIT &&			    inet_sk(sk)->inet_rcv_saddr == 0); 		/* Ignore non-transparent sockets,		   if XT_SOCKET_TRANSPARENT is used */		if (info && info->flags & XT_SOCKET_TRANSPARENT)			transparent = ((sk->sk_state != TCP_TIME_WAIT &&					inet_sk(sk)->transparent) ||				       (sk->sk_state == TCP_TIME_WAIT &&					inet_twsk(sk)->tw_transparent)); 		xt_socket_put_sk(sk); 		if (wildcard || !transparent)			sk = NULL;	} 	pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",		 protocol, &saddr, ntohs(sport),		 &daddr, ntohs(dport),		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); 	return (sk != NULL);} static boolsocket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par){	return socket_match(skb, par, NULL);} static boolsocket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par){	return socket_match(skb, par, par->matchinfo);} #ifdef XT_SOCKET_HAVE_IPV6 static intextract_icmp6_fields(const struct sk_buff *skb,		     unsigned int outside_hdrlen,		     int *protocol,		     struct in6_addr **raddr,		     struct in6_addr **laddr,		     __be16 *rport,		     __be16 *lport){	struct ipv6hdr *inside_iph, _inside_iph;	struct icmp6hdr *icmph, _icmph;	__be16 *ports, _ports[2];	u8 inside_nexthdr;	__be16 inside_fragoff;	int inside_hdrlen; 	icmph = skb_header_pointer(skb, outside_hdrlen,				   sizeof(_icmph), &_icmph);	if (icmph == NULL)		return 1; 	if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)		return 1; 	inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph);	if (inside_iph == NULL)		return 1;	inside_nexthdr = inside_iph->nexthdr; 	inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph),					 &inside_nexthdr, &inside_fragoff);	if (inside_hdrlen < 0)		return 1; /* hjm: Packet has no/incomplete transport layer headers. */ 	if (inside_nexthdr != IPPROTO_TCP &&	    inside_nexthdr != IPPROTO_UDP)		return 1; 	ports = skb_header_pointer(skb, inside_hdrlen,				   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_nexthdr;	*laddr = &inside_iph->saddr;	*lport = ports[0];	*raddr = &inside_iph->daddr;	*rport = ports[1]; 	return 0;} static boolsocket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par){	struct ipv6hdr *iph = ipv6_hdr(skb);	struct udphdr _hdr, *hp = NULL;	struct sock *sk;	struct in6_addr *daddr, *saddr;	__be16 dport, sport;	int thoff = 0, tproto;	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; 	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);	if (tproto < 0) {		pr_debug("unable to find transport header in IPv6 packet, dropping\n");		return NF_DROP;	} 	if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {		hp = skb_header_pointer(skb, thoff,					sizeof(_hdr), &_hdr);		if (hp == NULL)			return false; 		saddr = &iph->saddr;		sport = hp->source;		daddr = &iph->daddr;		dport = hp->dest; 	} else if (tproto == IPPROTO_ICMPV6) {		if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,					 &sport, &dport))			return false;	} else {		return false;	} 	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,				   saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);	if (sk != NULL) {		bool wildcard;		bool transparent = true; 		/* Ignore sockets listening on INADDR_ANY */		wildcard = (sk->sk_state != TCP_TIME_WAIT &&			    ipv6_addr_any(&inet6_sk(sk)->rcv_saddr)); 		/* Ignore non-transparent sockets,		   if XT_SOCKET_TRANSPARENT is used */		if (info && info->flags & XT_SOCKET_TRANSPARENT)			transparent = ((sk->sk_state != TCP_TIME_WAIT &&					inet_sk(sk)->transparent) ||				       (sk->sk_state == TCP_TIME_WAIT &&					inet_twsk(sk)->tw_transparent)); 		xt_socket_put_sk(sk); 		if (wildcard || !transparent)			sk = NULL;	} 	pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "		 "(orig %pI6:%hu) sock %p\n",		 tproto, saddr, ntohs(sport),		 daddr, ntohs(dport),		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); 	return (sk != NULL);}#endif static struct xt_match socket_mt_reg[] __read_mostly = {	{		.name		= "socket",		.revision	= 0,		.family		= NFPROTO_IPV4,		.match		= socket_mt4_v0,		.hooks		= (1 << NF_INET_PRE_ROUTING) |				  (1 << NF_INET_LOCAL_IN),		.me		= THIS_MODULE,	},	{		.name		= "socket",		.revision	= 1,		.family		= NFPROTO_IPV4,		.match		= socket_mt4_v1,		.matchsize	= sizeof(struct xt_socket_mtinfo1),		.hooks		= (1 << NF_INET_PRE_ROUTING) |				  (1 << NF_INET_LOCAL_IN),		.me		= THIS_MODULE,	},#ifdef XT_SOCKET_HAVE_IPV6	{		.name		= "socket",		.revision	= 1,		.family		= NFPROTO_IPV6,		.match		= socket_mt6_v1,		.matchsize	= sizeof(struct xt_socket_mtinfo1),		.hooks		= (1 << NF_INET_PRE_ROUTING) |				  (1 << NF_INET_LOCAL_IN),		.me		= THIS_MODULE,	},#endif}; static int __init socket_mt_init(void){	nf_defrag_ipv4_enable();#ifdef XT_SOCKET_HAVE_IPV6	nf_defrag_ipv6_enable();#endif 	return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));} static void __exit socket_mt_exit(void){	xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));} module_init(socket_mt_init);module_exit(socket_mt_exit); MODULE_LICENSE("GPL");MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");MODULE_DESCRIPTION("x_tables socket match module");MODULE_ALIAS("ipt_socket");MODULE_ALIAS("ip6t_socket");