[linux-2.6-block.git] / net / netfilter / nf_conntrack_sane.c

/* SANE connection tracking helper
 * (SANE = Scanner Access Now Easy)
 * For documentation about the SANE network protocol see
 * http://www.sane-project.org/html/doc015.html
 */

/* Copyright (C) 2007 Red Hat, Inc.
 * Author: Michal Schmidt <mschmidt@redhat.com>
 * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
 *  (C) 1999-2001 Paul `Rusty' Russell
 *  (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *  (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 *  (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
 *
 * 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/netfilter.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sane.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
MODULE_DESCRIPTION("SANE connection tracking helper");

static char *sane_buffer;

static DEFINE_SPINLOCK(nf_sane_lock);

#define MAX_PORTS 8
static u_int16_t ports[MAX_PORTS];
static unsigned int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);

struct sane_request {
	__be32 RPC_code;
#define SANE_NET_START      7   /* RPC code */

	__be32 handle;
};

struct sane_reply_net_start {
	__be32 status;
#define SANE_STATUS_SUCCESS 0

	__be16 zero;
	__be16 port;
	/* other fields aren't interesting for conntrack */
};

static int help(struct sk_buff *skb,
		unsigned int protoff,
		struct nf_conn *ct,
		enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff, datalen;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	void *sb_ptr;
	int ret = NF_ACCEPT;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_ct_sane_master *ct_sane_info;
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	struct sane_request *req;
	struct sane_reply_net_start *reply;

	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED &&
	    ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
		return NF_ACCEPT;

	/* Not a full tcp header? */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = protoff + th->doff * 4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	datalen = skb->len - dataoff;

	spin_lock_bh(&nf_sane_lock);
	sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer);
	BUG_ON(sb_ptr == NULL);

	if (dir == IP_CT_DIR_ORIGINAL) {
		if (datalen != sizeof(struct sane_request))
			goto out;

		req = sb_ptr;
		if (req->RPC_code != htonl(SANE_NET_START)) {
			/* Not an interesting command */
			ct_sane_info->state = SANE_STATE_NORMAL;
			goto out;
		}

		/* We're interested in the next reply */
		ct_sane_info->state = SANE_STATE_START_REQUESTED;
		goto out;
	}

	/* Is it a reply to an uninteresting command? */
	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
		goto out;

	/* It's a reply to SANE_NET_START. */
	ct_sane_info->state = SANE_STATE_NORMAL;

	if (datalen < sizeof(struct sane_reply_net_start)) {
		pr_debug("nf_ct_sane: NET_START reply too short\n");
		goto out;
	}

	reply = sb_ptr;
	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
		/* saned refused the command */
		pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
			 ntohl(reply->status));
		goto out;
	}

	/* Invalid saned reply? Ignore it. */
	if (reply->zero != 0)
		goto out;

	exp = nf_ct_expect_alloc(ct);
	if (exp == NULL) {
		ret = NF_DROP;
		goto out;
	}

	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &tuple->src.u3, &tuple->dst.u3,
			  IPPROTO_TCP, NULL, &reply->port);

	pr_debug("nf_ct_sane: expect: ");
	nf_ct_dump_tuple(&exp->tuple);

	/* Can't expect this?  Best to drop packet now. */
	if (nf_ct_expect_related(exp) != 0)
		ret = NF_DROP;

	nf_ct_expect_put(exp);

out:
	spin_unlock_bh(&nf_sane_lock);
	return ret;
}

static struct nf_conntrack_helper sane[MAX_PORTS][2] __read_mostly;
static char sane_names[MAX_PORTS][2][sizeof("sane-65535")] __read_mostly;

static const struct nf_conntrack_expect_policy sane_exp_policy = {
	.max_expected	= 1,
	.timeout	= 5 * 60,
};

/* don't make this __exit, since it's called from __init ! */
static void nf_conntrack_sane_fini(void)
{
	int i, j;

	for (i = 0; i < ports_c; i++) {
		for (j = 0; j < 2; j++) {
			pr_debug("nf_ct_sane: unregistering helper for pf: %d "
				 "port: %d\n",
				 sane[i][j].tuple.src.l3num, ports[i]);
			nf_conntrack_helper_unregister(&sane[i][j]);
		}
	}

	kfree(sane_buffer);
}

static int __init nf_conntrack_sane_init(void)
{
	int i, j = -1, ret = 0;
	char *tmpname;

	sane_buffer = kmalloc(65536, GFP_KERNEL);
	if (!sane_buffer)
		return -ENOMEM;

	if (ports_c == 0)
		ports[ports_c++] = SANE_PORT;

	/* FIXME should be configurable whether IPv4 and IPv6 connections
		 are tracked or not - YK */
	for (i = 0; i < ports_c; i++) {
		sane[i][0].tuple.src.l3num = PF_INET;
		sane[i][1].tuple.src.l3num = PF_INET6;
		for (j = 0; j < 2; j++) {
			sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
			sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
			sane[i][j].expect_policy = &sane_exp_policy;
			sane[i][j].me = THIS_MODULE;
			sane[i][j].help = help;
			tmpname = &sane_names[i][j][0];
			if (ports[i] == SANE_PORT)
				sprintf(tmpname, "sane");
			else
				sprintf(tmpname, "sane-%d", ports[i]);
			sane[i][j].name = tmpname;

			pr_debug("nf_ct_sane: registering helper for pf: %d "
				 "port: %d\n",
				 sane[i][j].tuple.src.l3num, ports[i]);
			ret = nf_conntrack_helper_register(&sane[i][j]);
			if (ret) {
				printk(KERN_ERR "nf_ct_sane: failed to "
				       "register helper for pf: %d port: %d\n",
					sane[i][j].tuple.src.l3num, ports[i]);
				nf_conntrack_sane_fini();
				return ret;
			}
		}
	}

	return 0;
}

module_init(nf_conntrack_sane_init);
module_exit(nf_conntrack_sane_fini);
Commit	Line	Data
6fecd198 MS	1	/* SANE connection tracking helper
	2	* (SANE = Scanner Access Now Easy)
	3	* For documentation about the SANE network protocol see
	4	* http://www.sane-project.org/html/doc015.html
	5	*/
	6
	7	/* Copyright (C) 2007 Red Hat, Inc.
	8	* Author: Michal Schmidt <mschmidt@redhat.com>
	9	* Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
	10	* (C) 1999-2001 Paul `Rusty' Russell
	11	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	12	* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
	13	* (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
	14	*
	15	* This program is free software; you can redistribute it and/or modify
	16	* it under the terms of the GNU General Public License version 2 as
	17	* published by the Free Software Foundation.
	18	*/
	19
	20	#include <linux/module.h>
	21	#include <linux/moduleparam.h>
	22	#include <linux/netfilter.h>
	23	#include <linux/in.h>
	24	#include <linux/tcp.h>
	25	#include <net/netfilter/nf_conntrack.h>
	26	#include <net/netfilter/nf_conntrack_helper.h>
	27	#include <net/netfilter/nf_conntrack_expect.h>
	28	#include <linux/netfilter/nf_conntrack_sane.h>
	29
	30	MODULE_LICENSE("GPL");
	31	MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
	32	MODULE_DESCRIPTION("SANE connection tracking helper");
	33
	34	static char *sane_buffer;
	35
	36	static DEFINE_SPINLOCK(nf_sane_lock);
	37
	38	#define MAX_PORTS 8
	39	static u_int16_t ports[MAX_PORTS];
	40	static unsigned int ports_c;
	41	module_param_array(ports, ushort, &ports_c, 0400);
	42
6fecd198 MS	43	struct sane_request {
	44	__be32 RPC_code;
	45	#define SANE_NET_START 7 /* RPC code */
	46
	47	__be32 handle;
	48	};
	49
	50	struct sane_reply_net_start {
	51	__be32 status;
	52	#define SANE_STATUS_SUCCESS 0
	53
	54	__be16 zero;
	55	__be16 port;
	56	/* other fields aren't interesting for conntrack */
	57	};
	58
3db05fea	59	static int help(struct sk_buff *skb,
6fecd198 MS	60	unsigned int protoff,
	61	struct nf_conn *ct,
	62	enum ip_conntrack_info ctinfo)
	63	{
	64	unsigned int dataoff, datalen;
02e23f40 JE	65	const struct tcphdr *th;
	66	struct tcphdr _tcph;
	67	void *sb_ptr;
6fecd198 MS	68	int ret = NF_ACCEPT;
	69	int dir = CTINFO2DIR(ctinfo);
	70	struct nf_ct_sane_master *ct_sane_info;
	71	struct nf_conntrack_expect *exp;
	72	struct nf_conntrack_tuple *tuple;
	73	struct sane_request *req;
	74	struct sane_reply_net_start *reply;
6fecd198 MS	75
	76	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
	77	/* Until there's been traffic both ways, don't look in packets. */
	78	if (ctinfo != IP_CT_ESTABLISHED &&
	79	ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
	80	return NF_ACCEPT;
	81
	82	/* Not a full tcp header? */
3db05fea	83	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
6fecd198 MS	84	if (th == NULL)
	85	return NF_ACCEPT;
	86
	87	/* No data? */
	88	dataoff = protoff + th->doff * 4;
3db05fea	89	if (dataoff >= skb->len)
6fecd198 MS	90	return NF_ACCEPT;
6fecd198 MS	91
3db05fea	92	datalen = skb->len - dataoff;
6fecd198 MS	93
6fecd198 MS	94	spin_lock_bh(&nf_sane_lock);
3db05fea	95	sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer);
6fecd198 MS	96	BUG_ON(sb_ptr == NULL);
	97
	98	if (dir == IP_CT_DIR_ORIGINAL) {
	99	if (datalen != sizeof(struct sane_request))
	100	goto out;
	101
02e23f40	102	req = sb_ptr;
6fecd198 MS	103	if (req->RPC_code != htonl(SANE_NET_START)) {
	104	/* Not an interesting command */
	105	ct_sane_info->state = SANE_STATE_NORMAL;
	106	goto out;
	107	}
	108
	109	/* We're interested in the next reply */
	110	ct_sane_info->state = SANE_STATE_START_REQUESTED;
	111	goto out;
	112	}
	113
	114	/* Is it a reply to an uninteresting command? */
	115	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
	116	goto out;
	117
	118	/* It's a reply to SANE_NET_START. */
	119	ct_sane_info->state = SANE_STATE_NORMAL;
	120
	121	if (datalen < sizeof(struct sane_reply_net_start)) {
0d53778e	122	pr_debug("nf_ct_sane: NET_START reply too short\n");
6fecd198 MS	123	goto out;
	124	}
	125
02e23f40	126	reply = sb_ptr;
6fecd198 MS	127	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
6fecd198 MS	128	/* saned refused the command */
0d53778e PM	129	pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
0d53778e PM	130	ntohl(reply->status));
6fecd198 MS	131	goto out;
	132	}
	133
	134	/* Invalid saned reply? Ignore it. */
	135	if (reply->zero != 0)
	136	goto out;
	137
6823645d	138	exp = nf_ct_expect_alloc(ct);
6fecd198 MS	139	if (exp == NULL) {
	140	ret = NF_DROP;
	141	goto out;
	142	}
	143
	144	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
5e8fbe2a	145	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
6002f266	146	&tuple->src.u3, &tuple->dst.u3,
6823645d	147	IPPROTO_TCP, NULL, &reply->port);
6fecd198	148
0d53778e	149	pr_debug("nf_ct_sane: expect: ");
3c9fba65	150	nf_ct_dump_tuple(&exp->tuple);
6fecd198 MS	151
6fecd198 MS	152	/* Can't expect this? Best to drop packet now. */
6823645d	153	if (nf_ct_expect_related(exp) != 0)
6fecd198 MS	154	ret = NF_DROP;
6fecd198 MS	155
6823645d	156	nf_ct_expect_put(exp);
6fecd198 MS	157
	158	out:
	159	spin_unlock_bh(&nf_sane_lock);
	160	return ret;
	161	}
	162
ec59a111 PM	163	static struct nf_conntrack_helper sane[MAX_PORTS][2] __read_mostly;
ec59a111 PM	164	static char sane_names[MAX_PORTS][2][sizeof("sane-65535")] __read_mostly;
6fecd198	165
6002f266 PM	166	static const struct nf_conntrack_expect_policy sane_exp_policy = {
	167	.max_expected = 1,
	168	.timeout = 5 * 60,
	169	};
	170
6fecd198 MS	171	/* don't make this __exit, since it's called from __init ! */
	172	static void nf_conntrack_sane_fini(void)
	173	{
	174	int i, j;
	175
	176	for (i = 0; i < ports_c; i++) {
	177	for (j = 0; j < 2; j++) {
0d53778e PM	178	pr_debug("nf_ct_sane: unregistering helper for pf: %d "
	179	"port: %d\n",
	180	sane[i][j].tuple.src.l3num, ports[i]);
6fecd198 MS	181	nf_conntrack_helper_unregister(&sane[i][j]);
	182	}
	183	}
	184
	185	kfree(sane_buffer);
	186	}
	187
	188	static int __init nf_conntrack_sane_init(void)
	189	{
	190	int i, j = -1, ret = 0;
	191	char *tmpname;
	192
	193	sane_buffer = kmalloc(65536, GFP_KERNEL);
	194	if (!sane_buffer)
	195	return -ENOMEM;
	196
	197	if (ports_c == 0)
	198	ports[ports_c++] = SANE_PORT;
	199
	200	/* FIXME should be configurable whether IPv4 and IPv6 connections
	201	are tracked or not - YK */
	202	for (i = 0; i < ports_c; i++) {
	203	sane[i][0].tuple.src.l3num = PF_INET;
	204	sane[i][1].tuple.src.l3num = PF_INET6;
	205	for (j = 0; j < 2; j++) {
	206	sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	207	sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
6002f266	208	sane[i][j].expect_policy = &sane_exp_policy;
6fecd198 MS	209	sane[i][j].me = THIS_MODULE;
	210	sane[i][j].help = help;
	211	tmpname = &sane_names[i][j][0];
	212	if (ports[i] == SANE_PORT)
	213	sprintf(tmpname, "sane");
	214	else
	215	sprintf(tmpname, "sane-%d", ports[i]);
	216	sane[i][j].name = tmpname;
	217
0d53778e PM	218	pr_debug("nf_ct_sane: registering helper for pf: %d "
	219	"port: %d\n",
	220	sane[i][j].tuple.src.l3num, ports[i]);
6fecd198 MS	221	ret = nf_conntrack_helper_register(&sane[i][j]);
	222	if (ret) {
	223	printk(KERN_ERR "nf_ct_sane: failed to "
	224	"register helper for pf: %d port: %d\n",
	225	sane[i][j].tuple.src.l3num, ports[i]);
	226	nf_conntrack_sane_fini();
	227	return ret;
	228	}
	229	}
	230	}
	231
	232	return 0;
	233	}
	234
	235	module_init(nf_conntrack_sane_init);
	236	module_exit(nf_conntrack_sane_fini);