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

/* FTP extension for TCP NAT alteration. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 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/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/moduleparam.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_conntrack_ftp.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>

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

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

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

static int
mangle_rfc959_packet(struct sk_buff **pskb,
		     u_int32_t newip,
		     u_int16_t port,
		     unsigned int matchoff,
		     unsigned int matchlen,
		     struct ip_conntrack *ct,
		     enum ip_conntrack_info ctinfo,
		     u32 *seq)
{
	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 ip_nat_mangle_tcp_packet\n");

	*seq += strlen(buffer) - matchlen;
	return ip_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,
		   u_int32_t newip,
		   u_int16_t port,
		   unsigned int matchoff,
		   unsigned int matchlen,
		   struct ip_conntrack *ct,
		   enum ip_conntrack_info ctinfo,
		   u32 *seq)
{
	char buffer[sizeof("|1|255.255.255.255|65535|")];

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

	DEBUGP("calling ip_nat_mangle_tcp_packet\n");

	*seq += strlen(buffer) - matchlen;
	return ip_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,
		   u_int32_t newip,
		   u_int16_t port,
		   unsigned int matchoff,
		   unsigned int matchlen,
		   struct ip_conntrack *ct,
		   enum ip_conntrack_info ctinfo,
		   u32 *seq)
{
	char buffer[sizeof("|||65535|")];

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

	DEBUGP("calling ip_nat_mangle_tcp_packet\n");

	*seq += strlen(buffer) - matchlen;
	return ip_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff, 
					matchlen, buffer, strlen(buffer));
}

static int (*mangle[])(struct sk_buff **, u_int32_t, u_int16_t,
		     unsigned int,
		     unsigned int,
		     struct ip_conntrack *,
		     enum ip_conntrack_info,
		     u32 *seq)
= { [IP_CT_FTP_PORT] = mangle_rfc959_packet,
    [IP_CT_FTP_PASV] = mangle_rfc959_packet,
    [IP_CT_FTP_EPRT] = mangle_eprt_packet,
    [IP_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 ip_nat_ftp(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       enum ip_ct_ftp_type type,
			       unsigned int matchoff,
			       unsigned int matchlen,
			       struct ip_conntrack_expect *exp,
			       u32 *seq)
{
	u_int32_t newip;
	u_int16_t port;
	int dir = CTINFO2DIR(ctinfo);
	struct ip_conntrack *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.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 = ip_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 (ip_conntrack_expect_related(exp) == 0)
			break;
	}

	if (port == 0)
		return NF_DROP;

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

static void __exit ip_nat_ftp_fini(void)
{
	ip_nat_ftp_hook = NULL;
	/* Make sure noone calls it, meanwhile. */
	synchronize_net();
}

static int __init ip_nat_ftp_init(void)
{
	BUG_ON(ip_nat_ftp_hook);
	ip_nat_ftp_hook = ip_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(ip_nat_ftp_init);
module_exit(ip_nat_ftp_fini);
Commit	Line	Data
1da177e4 LT	1	/* FTP extension for TCP NAT alteration. */
	2
	3	/* (C) 1999-2001 Paul `Rusty' Russell
	4	* (C) 2002-2004 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/netfilter_ipv4.h>
	13	#include <linux/ip.h>
	14	#include <linux/tcp.h>
	15	#include <linux/moduleparam.h>
	16	#include <net/tcp.h>
	17	#include <linux/netfilter_ipv4/ip_nat.h>
	18	#include <linux/netfilter_ipv4/ip_nat_helper.h>
	19	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	20	#include <linux/netfilter_ipv4/ip_conntrack_ftp.h>
	21	#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
	22
	23	MODULE_LICENSE("GPL");
	24	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
	25	MODULE_DESCRIPTION("ftp NAT helper");
	26
	27	#if 0
	28	#define DEBUGP printk
	29	#else
	30	#define DEBUGP(format, args...)
	31	#endif
	32
	33	/* FIXME: Time out? --RR */
	34
	35	static int
	36	mangle_rfc959_packet(struct sk_buff **pskb,
	37	u_int32_t newip,
	38	u_int16_t port,
	39	unsigned int matchoff,
	40	unsigned int matchlen,
	41	struct ip_conntrack *ct,
	42	enum ip_conntrack_info ctinfo,
	43	u32 *seq)
	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 ip_nat_mangle_tcp_packet\n");
	51
	52	*seq += strlen(buffer) - matchlen;
	53	return ip_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
	54	matchlen, buffer, strlen(buffer));
	55	}
	56
	57	/* \|1\|132.235.1.2\|6275\| */
	58	static int
	59	mangle_eprt_packet(struct sk_buff **pskb,
	60	u_int32_t newip,
	61	u_int16_t port,
	62	unsigned int matchoff,
	63	unsigned int matchlen,
	64	struct ip_conntrack *ct,
65	enum ip_conntrack_info ctinfo,
66	u32 *seq)
67	{
68	char buffer[sizeof("\|1\|255.255.255.255\|65535\|")];
69
70	sprintf(buffer, "\|1\|%u.%u.%u.%u\|%u\|", NIPQUAD(newip), port);
71
72	DEBUGP("calling ip_nat_mangle_tcp_packet\n");
73
74	*seq += strlen(buffer) - matchlen;
75	return ip_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
76	matchlen, buffer, strlen(buffer));
77	}
78
79	/* \|1\|132.235.1.2\|6275\| */
80	static int
81	mangle_epsv_packet(struct sk_buff **pskb,
82	u_int32_t newip,
83	u_int16_t port,
84	unsigned int matchoff,
85	unsigned int matchlen,
86	struct ip_conntrack *ct,
87	enum ip_conntrack_info ctinfo,
88	u32 *seq)
89	{
90	char buffer[sizeof("\|\|\|65535\|")];
91
92	sprintf(buffer, "\|\|\|%u\|", port);
93
94	DEBUGP("calling ip_nat_mangle_tcp_packet\n");
95
96	*seq += strlen(buffer) - matchlen;
97	return ip_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
98	matchlen, buffer, strlen(buffer));
99	}
100
101	static int (mangle[])(struct sk_buff *, u_int32_t, u_int16_t,
102	unsigned int,
103	unsigned int,
104	struct ip_conntrack *,
105	enum ip_conntrack_info,
106	u32 *seq)
107	= { [IP_CT_FTP_PORT] = mangle_rfc959_packet,
108	[IP_CT_FTP_PASV] = mangle_rfc959_packet,
109	[IP_CT_FTP_EPRT] = mangle_eprt_packet,
110	[IP_CT_FTP_EPSV] = mangle_epsv_packet
111	};
112
113	/* So, this packet has hit the connection tracking matching code.
114	Mangle it, and change the expectation to match the new version. */
115	static unsigned int ip_nat_ftp(struct sk_buff **pskb,
116	enum ip_conntrack_info ctinfo,
117	enum ip_ct_ftp_type type,
118	unsigned int matchoff,
119	unsigned int matchlen,
120	struct ip_conntrack_expect *exp,
121	u32 *seq)
122	{
123	u_int32_t newip;
124	u_int16_t port;
125	int dir = CTINFO2DIR(ctinfo);
126	struct ip_conntrack *ct = exp->master;
127
128	DEBUGP("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen);
129
130	/* Connection will come from wherever this packet goes, hence !dir */
131	newip = ct->tuplehash[!dir].tuple.dst.ip;
132	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
133	exp->dir = !dir;
134
135	/* When you see the packet, we need to NAT it the same as the
136	* this one. */
137	exp->expectfn = ip_nat_follow_master;
138
139	/* Try to get same port: if not, try to change it. */
140	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
141	exp->tuple.dst.u.tcp.port = htons(port);
142	if (ip_conntrack_expect_related(exp) == 0)
143	break;
144	}
145
4acdbdbe	146	if (port == 0)
1da177e4	147	return NF_DROP;
1da177e4 LT	148
	149	if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo,
	150	seq)) {
	151	ip_conntrack_unexpect_related(exp);
	152	return NF_DROP;
	153	}
	154	return NF_ACCEPT;
	155	}
	156
65b4b4e8	157	static void __exit ip_nat_ftp_fini(void)
1da177e4 LT	158	{
	159	ip_nat_ftp_hook = NULL;
	160	/* Make sure noone calls it, meanwhile. */
	161	synchronize_net();
	162	}
	163
65b4b4e8	164	static int __init ip_nat_ftp_init(void)
1da177e4 LT	165	{
	166	BUG_ON(ip_nat_ftp_hook);
	167	ip_nat_ftp_hook = ip_nat_ftp;
	168	return 0;
	169	}
	170
	171	/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
	172	static int warn_set(const char val, struct kernel_param kp)
	173	{
367cb704	174	printk(KERN_INFO KBUILD_MODNAME
1da177e4 LT	175	": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
	176	return 0;
	177	}
	178	module_param_call(ports, warn_set, NULL, NULL, 0);
	179
65b4b4e8 AM	180	module_init(ip_nat_ftp_init);
65b4b4e8 AM	181	module_exit(ip_nat_ftp_fini);