[deliverable/linux.git] / net / netfilter / xt_socket.c

/*
 * 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.
 *
 */

#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 defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
#define XT_SOCKET_HAVE_CONNTRACK 1
#include <net/netfilter/nf_conntrack.h>
#endif

static int
extract_icmp_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 bool
socket_mt(const struct sk_buff *skb,
	  const struct net_device *in,
	  const struct net_device *out,
	  const struct xt_match *match,
	  const void *matchinfo,
	  int offset,
	  unsigned int protoff,
	  bool *hotdrop)
{
	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_icmp_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 && (ct != &nf_conntrack_untracked) &&
	    ((iph->protocol != IPPROTO_ICMP &&
	      ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) ||
	     (iph->protocol == IPPROTO_ICMP &&
	      ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) &&
	    (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, in, false);
	if (sk != NULL) {
		bool wildcard = (inet_sk(sk)->rcv_saddr == 0);

		nf_tproxy_put_sock(sk);
		if (wildcard)
			sk = NULL;
	}

	pr_debug("socket match: proto %u %08x:%u -> %08x:%u "
		 "(orig %08x:%u) sock %p\n",
		 protocol, ntohl(saddr), ntohs(sport),
		 ntohl(daddr), ntohs(dport),
		 ntohl(iph->daddr), hp ? ntohs(hp->dest) : 0, sk);

	return (sk != NULL);
}

static struct xt_match socket_mt_reg __read_mostly = {
	.name		= "socket",
	.family		= AF_INET,
	.match		= socket_mt,
	.hooks		= 1 << NF_INET_PRE_ROUTING,
	.me		= THIS_MODULE,
};

static int __init socket_mt_init(void)
{
	nf_defrag_ipv4_enable();
	return xt_register_match(&socket_mt_reg);
}

static void __exit socket_mt_exit(void)
{
	xt_unregister_match(&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");
Commit	Line	Data
136cdc71 KK	1	/*
	2	* Transparent proxy support for Linux/iptables
	3	*
	4	* Copyright (C) 2007-2008 BalaBit IT Ltd.
	5	* Author: Krisztian Kovacs
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	*/
	12
	13	#include <linux/module.h>
	14	#include <linux/skbuff.h>
	15	#include <linux/netfilter/x_tables.h>
	16	#include <linux/netfilter_ipv4/ip_tables.h>
	17	#include <net/tcp.h>
	18	#include <net/udp.h>
	19	#include <net/icmp.h>
	20	#include <net/sock.h>
	21	#include <net/inet_sock.h>
	22	#include <net/netfilter/nf_tproxy_core.h>
	23	#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
	24
	25	#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
	26	#define XT_SOCKET_HAVE_CONNTRACK 1
	27	#include <net/netfilter/nf_conntrack.h>
	28	#endif
	29
	30	static int
	31	extract_icmp_fields(const struct sk_buff *skb,
	32	u8 *protocol,
	33	__be32 *raddr,
	34	__be32 *laddr,
	35	__be16 *rport,
	36	__be16 *lport)
	37	{
	38	unsigned int outside_hdrlen = ip_hdrlen(skb);
	39	struct iphdr *inside_iph, _inside_iph;
	40	struct icmphdr *icmph, _icmph;
	41	__be16 *ports, _ports[2];
	42
	43	icmph = skb_header_pointer(skb, outside_hdrlen,
	44	sizeof(_icmph), &_icmph);
	45	if (icmph == NULL)
	46	return 1;
	47
	48	switch (icmph->type) {
	49	case ICMP_DEST_UNREACH:
	50	case ICMP_SOURCE_QUENCH:
	51	case ICMP_REDIRECT:
	52	case ICMP_TIME_EXCEEDED:
	53	case ICMP_PARAMETERPROB:
	54	break;
	55	default:
	56	return 1;
	57	}
	58
	59	inside_iph = skb_header_pointer(skb, outside_hdrlen +
	60	sizeof(struct icmphdr),
	61	sizeof(_inside_iph), &_inside_iph);
	62	if (inside_iph == NULL)
	63	return 1;
	64
65	if (inside_iph->protocol != IPPROTO_TCP &&
66	inside_iph->protocol != IPPROTO_UDP)
67	return 1;
68
69	ports = skb_header_pointer(skb, outside_hdrlen +
70	sizeof(struct icmphdr) +
71	(inside_iph->ihl << 2),
72	sizeof(_ports), &_ports);
73	if (ports == NULL)
74	return 1;
75
76	/* the inside IP packet is the one quoted from our side, thus
77	* its saddr is the local address */
78	*protocol = inside_iph->protocol;
79	*laddr = inside_iph->saddr;
80	*lport = ports[0];
81	*raddr = inside_iph->daddr;
82	*rport = ports[1];
83
84	return 0;
85	}
86
87
88	static bool
89	socket_mt(const struct sk_buff *skb,
90	const struct net_device *in,
91	const struct net_device *out,
92	const struct xt_match *match,
93	const void *matchinfo,
94	int offset,
95	unsigned int protoff,
96	bool *hotdrop)
97	{
98	const struct iphdr *iph = ip_hdr(skb);
99	struct udphdr _hdr, *hp = NULL;
100	struct sock *sk;
101	__be32 daddr, saddr;
102	__be16 dport, sport;
103	u8 protocol;
104	#ifdef XT_SOCKET_HAVE_CONNTRACK
105	struct nf_conn const *ct;
106	enum ip_conntrack_info ctinfo;
107	#endif
108
109	if (iph->protocol == IPPROTO_UDP \|\| iph->protocol == IPPROTO_TCP) {
110	hp = skb_header_pointer(skb, ip_hdrlen(skb),
111	sizeof(_hdr), &_hdr);
112	if (hp == NULL)
113	return false;
114
115	protocol = iph->protocol;
116	saddr = iph->saddr;
117	sport = hp->source;
118	daddr = iph->daddr;
119	dport = hp->dest;
120
121	} else if (iph->protocol == IPPROTO_ICMP) {
122	if (extract_icmp_fields(skb, &protocol, &saddr, &daddr,
123	&sport, &dport))
124	return false;
125	} else {
126	return false;
127	}
128
129	#ifdef XT_SOCKET_HAVE_CONNTRACK
130	/* Do the lookup with the original socket address in case this is a
131	* reply packet of an established SNAT-ted connection. */
132
133	ct = nf_ct_get(skb, &ctinfo);
134	if (ct && (ct != &nf_conntrack_untracked) &&
135	((iph->protocol != IPPROTO_ICMP &&
136	ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) \|\|
137	(iph->protocol == IPPROTO_ICMP &&
138	ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) &&
139	(ct->status & IPS_SRC_NAT_DONE)) {
140
141	daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
142	dport = (iph->protocol == IPPROTO_TCP) ?
143	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
144	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
145	}
146	#endif
147
148	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
149	saddr, daddr, sport, dport, in, false);
150	if (sk != NULL) {
151	bool wildcard = (inet_sk(sk)->rcv_saddr == 0);
152
153	nf_tproxy_put_sock(sk);
154	if (wildcard)
155	sk = NULL;
156	}
157
158	pr_debug("socket match: proto %u %08x:%u -> %08x:%u "
159	"(orig %08x:%u) sock %p\n",
160	protocol, ntohl(saddr), ntohs(sport),
161	ntohl(daddr), ntohs(dport),
162	ntohl(iph->daddr), hp ? ntohs(hp->dest) : 0, sk);
163
164	return (sk != NULL);
165	}
166
167	static struct xt_match socket_mt_reg __read_mostly = {
168	.name = "socket",
169	.family = AF_INET,
170	.match = socket_mt,
171	.hooks = 1 << NF_INET_PRE_ROUTING,
172	.me = THIS_MODULE,
173	};
174
175	static int __init socket_mt_init(void)
176	{
177	nf_defrag_ipv4_enable();
178	return xt_register_match(&socket_mt_reg);
179	}
180
181	static void __exit socket_mt_exit(void)
182	{
183	xt_unregister_match(&socket_mt_reg);
184	}
185
186	module_init(socket_mt_init);
187	module_exit(socket_mt_exit);
188
189	MODULE_LICENSE("GPL");
190	MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
191	MODULE_DESCRIPTION("x_tables socket match module");
192	MODULE_ALIAS("ipt_socket");