[deliverable/linux.git] / net / ipv4 / netfilter / nf_nat_ftp.c

/* FTP extension for TCP NAT alteration. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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/moduleparam.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_nat_rule.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_ftp.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
MODULE_DESCRIPTION("ftp NAT helper");
MODULE_ALIAS("ip_nat_ftp");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

/* FIXME: Time out? --RR */

static int
mangle_rfc959_packet(struct sk_buff **pskb,
		     __be32 newip,
		     u_int16_t port,
		     unsigned int matchoff,
		     unsigned int matchlen,
		     struct nf_conn *ct,
		     enum ip_conntrack_info ctinfo)
{
	char buffer[sizeof("nnn,nnn,nnn,nnn,nnn,nnn")];

	sprintf(buffer, "%u,%u,%u,%u,%u,%u",
		NIPQUAD(newip), port>>8, port&0xFF);

	DEBUGP("calling nf_nat_mangle_tcp_packet\n");

	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
					matchlen, buffer, strlen(buffer));
}

/* |1|132.235.1.2|6275| */
static int
mangle_eprt_packet(struct sk_buff **pskb,
		   __be32 newip,
		   u_int16_t port,
		   unsigned int matchoff,
		   unsigned int matchlen,
		   struct nf_conn *ct,
		   enum ip_conntrack_info ctinfo)
{
	char buffer[sizeof("|1|255.255.255.255|65535|")];

	sprintf(buffer, "|1|%u.%u.%u.%u|%u|", NIPQUAD(newip), port);

	DEBUGP("calling nf_nat_mangle_tcp_packet\n");

	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
					matchlen, buffer, strlen(buffer));
}

/* |1|132.235.1.2|6275| */
static int
mangle_epsv_packet(struct sk_buff **pskb,
		   __be32 newip,
		   u_int16_t port,
		   unsigned int matchoff,
		   unsigned int matchlen,
		   struct nf_conn *ct,
		   enum ip_conntrack_info ctinfo)
{
	char buffer[sizeof("|||65535|")];

	sprintf(buffer, "|||%u|", port);

	DEBUGP("calling nf_nat_mangle_tcp_packet\n");

	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
					matchlen, buffer, strlen(buffer));
}

static int (*mangle[])(struct sk_buff **, __be32, u_int16_t,
		       unsigned int, unsigned int, struct nf_conn *,
		       enum ip_conntrack_info)
= {
	[NF_CT_FTP_PORT] = mangle_rfc959_packet,
	[NF_CT_FTP_PASV] = mangle_rfc959_packet,
	[NF_CT_FTP_EPRT] = mangle_eprt_packet,
	[NF_CT_FTP_EPSV] = mangle_epsv_packet
};

/* So, this packet has hit the connection tracking matching code.
   Mangle it, and change the expectation to match the new version. */
static unsigned int nf_nat_ftp(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       enum nf_ct_ftp_type type,
			       unsigned int matchoff,
			       unsigned int matchlen,
			       struct nf_conntrack_expect *exp)
{
	__be32 newip;
	u_int16_t port;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_conn *ct = exp->master;

	DEBUGP("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen);

	/* Connection will come from wherever this packet goes, hence !dir */
	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
	exp->dir = !dir;

	/* When you see the packet, we need to NAT it the same as the
	 * this one. */
	exp->expectfn = nf_nat_follow_master;

	/* Try to get same port: if not, try to change it. */
	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
		exp->tuple.dst.u.tcp.port = htons(port);
		if (nf_ct_expect_related(exp) == 0)
			break;
	}

	if (port == 0)
		return NF_DROP;

	if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo)) {
		nf_ct_unexpect_related(exp);
		return NF_DROP;
	}
	return NF_ACCEPT;
}

static void __exit nf_nat_ftp_fini(void)
{
	rcu_assign_pointer(nf_nat_ftp_hook, NULL);
	synchronize_rcu();
}

static int __init nf_nat_ftp_init(void)
{
	BUG_ON(rcu_dereference(nf_nat_ftp_hook));
	rcu_assign_pointer(nf_nat_ftp_hook, nf_nat_ftp);
	return 0;
}

/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
static int warn_set(const char *val, struct kernel_param *kp)
{
	printk(KERN_INFO KBUILD_MODNAME
	       ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
	return 0;
}
module_param_call(ports, warn_set, NULL, NULL, 0);

module_init(nf_nat_ftp_init);
module_exit(nf_nat_ftp_fini);
Commit	Line	Data
55a73324 JK	1	/* FTP extension for TCP NAT alteration. */
	2
	3	/* (C) 1999-2001 Paul `Rusty' Russell
	4	* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/moduleparam.h>
	13	#include <linux/ip.h>
	14	#include <linux/tcp.h>
	15	#include <linux/netfilter_ipv4.h>
	16	#include <net/netfilter/nf_nat.h>
	17	#include <net/netfilter/nf_nat_helper.h>
	18	#include <net/netfilter/nf_nat_rule.h>
	19	#include <net/netfilter/nf_conntrack_helper.h>
	20	#include <net/netfilter/nf_conntrack_expect.h>
	21	#include <linux/netfilter/nf_conntrack_ftp.h>
	22
	23	MODULE_LICENSE("GPL");
	24	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
	25	MODULE_DESCRIPTION("ftp NAT helper");
	26	MODULE_ALIAS("ip_nat_ftp");
	27
	28	#if 0
	29	#define DEBUGP printk
	30	#else
	31	#define DEBUGP(format, args...)
	32	#endif
	33
	34	/* FIXME: Time out? --RR */
	35
	36	static int
	37	mangle_rfc959_packet(struct sk_buff **pskb,
	38	__be32 newip,
	39	u_int16_t port,
	40	unsigned int matchoff,
	41	unsigned int matchlen,
	42	struct nf_conn *ct,
25b86e05	43	enum ip_conntrack_info ctinfo)
55a73324 JK	44	{
	45	char buffer[sizeof("nnn,nnn,nnn,nnn,nnn,nnn")];
	46
	47	sprintf(buffer, "%u,%u,%u,%u,%u,%u",
	48	NIPQUAD(newip), port>>8, port&0xFF);
	49
	50	DEBUGP("calling nf_nat_mangle_tcp_packet\n");
	51
55a73324 JK	52	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
	53	matchlen, buffer, strlen(buffer));
	54	}
	55
	56	/* \|1\|132.235.1.2\|6275\| */
	57	static int
	58	mangle_eprt_packet(struct sk_buff **pskb,
	59	__be32 newip,
	60	u_int16_t port,
	61	unsigned int matchoff,
	62	unsigned int matchlen,
	63	struct nf_conn *ct,
25b86e05	64	enum ip_conntrack_info ctinfo)
55a73324 JK	65	{
	66	char buffer[sizeof("\|1\|255.255.255.255\|65535\|")];
	67
	68	sprintf(buffer, "\|1\|%u.%u.%u.%u\|%u\|", NIPQUAD(newip), port);
	69
	70	DEBUGP("calling nf_nat_mangle_tcp_packet\n");
	71
55a73324 JK	72	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
	73	matchlen, buffer, strlen(buffer));
	74	}
	75
	76	/* \|1\|132.235.1.2\|6275\| */
	77	static int
	78	mangle_epsv_packet(struct sk_buff **pskb,
	79	__be32 newip,
	80	u_int16_t port,
	81	unsigned int matchoff,
	82	unsigned int matchlen,
	83	struct nf_conn *ct,
25b86e05	84	enum ip_conntrack_info ctinfo)
55a73324 JK	85	{
	86	char buffer[sizeof("\|\|\|65535\|")];
	87
	88	sprintf(buffer, "\|\|\|%u\|", port);
	89
	90	DEBUGP("calling nf_nat_mangle_tcp_packet\n");
	91
55a73324 JK	92	return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
	93	matchlen, buffer, strlen(buffer));
	94	}
	95
	96	static int (mangle[])(struct sk_buff *, __be32, u_int16_t,
	97	unsigned int, unsigned int, struct nf_conn *,
25b86e05	98	enum ip_conntrack_info)
55a73324 JK	99	= {
	100	[NF_CT_FTP_PORT] = mangle_rfc959_packet,
	101	[NF_CT_FTP_PASV] = mangle_rfc959_packet,
	102	[NF_CT_FTP_EPRT] = mangle_eprt_packet,
	103	[NF_CT_FTP_EPSV] = mangle_epsv_packet
	104	};
	105
	106	/* So, this packet has hit the connection tracking matching code.
	107	Mangle it, and change the expectation to match the new version. */
	108	static unsigned int nf_nat_ftp(struct sk_buff **pskb,
	109	enum ip_conntrack_info ctinfo,
	110	enum nf_ct_ftp_type type,
	111	unsigned int matchoff,
	112	unsigned int matchlen,
25b86e05	113	struct nf_conntrack_expect *exp)
55a73324 JK	114	{
	115	__be32 newip;
	116	u_int16_t port;
	117	int dir = CTINFO2DIR(ctinfo);
	118	struct nf_conn *ct = exp->master;
	119
	120	DEBUGP("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen);
	121
	122	/* Connection will come from wherever this packet goes, hence !dir */
	123	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	124	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
	125	exp->dir = !dir;
	126
	127	/* When you see the packet, we need to NAT it the same as the
	128	* this one. */
	129	exp->expectfn = nf_nat_follow_master;
	130
	131	/* Try to get same port: if not, try to change it. */
	132	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
	133	exp->tuple.dst.u.tcp.port = htons(port);
6823645d	134	if (nf_ct_expect_related(exp) == 0)
55a73324 JK	135	break;
	136	}
	137
	138	if (port == 0)
	139	return NF_DROP;
	140
25b86e05	141	if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo)) {
6823645d	142	nf_ct_unexpect_related(exp);
55a73324 JK	143	return NF_DROP;
	144	}
	145	return NF_ACCEPT;
	146	}
	147
	148	static void __exit nf_nat_ftp_fini(void)
	149	{
	150	rcu_assign_pointer(nf_nat_ftp_hook, NULL);
	151	synchronize_rcu();
	152	}
	153
	154	static int __init nf_nat_ftp_init(void)
	155	{
	156	BUG_ON(rcu_dereference(nf_nat_ftp_hook));
	157	rcu_assign_pointer(nf_nat_ftp_hook, nf_nat_ftp);
	158	return 0;
	159	}
	160
	161	/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
	162	static int warn_set(const char val, struct kernel_param kp)
	163	{
	164	printk(KERN_INFO KBUILD_MODNAME
	165	": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
	166	return 0;
	167	}
	168	module_param_call(ports, warn_set, NULL, NULL, 0);
	169
	170	module_init(nf_nat_ftp_init);
	171	module_exit(nf_nat_ftp_fini);