[net-next-2.6.git] / net / netfilter / nf_conntrack_irc.c

/* IRC extension for IP connection tracking, Version 1.21
 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
 * based on RR's ip_conntrack_ftp.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/netfilter.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_irc.h>

#define MAX_PORTS 8
static unsigned short ports[MAX_PORTS];
static unsigned int ports_c;
static unsigned int max_dcc_channels = 8;
static unsigned int dcc_timeout __read_mostly = 300;
/* This is slow, but it's simple. --RR */
static char *irc_buffer;
static DEFINE_SPINLOCK(irc_buffer_lock);

unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
				enum ip_conntrack_info ctinfo,
				unsigned int matchoff,
				unsigned int matchlen,
				struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_irc_hook);

MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_conntrack_irc");
MODULE_ALIAS_NFCT_HELPER("irc");

module_param_array(ports, ushort, &ports_c, 0400);
MODULE_PARM_DESC(ports, "port numbers of IRC servers");
module_param(max_dcc_channels, uint, 0400);
MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
				   "IRC session");
module_param(dcc_timeout, uint, 0400);
MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");

static const char *const dccprotos[] = {
	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
};

#define MINMATCHLEN	5

/* tries to get the ip_addr and port out of a dcc command
 * return value: -1 on failure, 0 on success
 *	data		pointer to first byte of DCC command data
 *	data_end	pointer to last byte of dcc command data
 *	ip		returns parsed ip of dcc command
 *	port		returns parsed port of dcc command
 *	ad_beg_p	returns pointer to first byte of addr data
 *	ad_end_p	returns pointer to last byte of addr data
 */
static int parse_dcc(char *data, const char *data_end, __be32 *ip,
		     u_int16_t *port, char **ad_beg_p, char **ad_end_p)
{
	char *tmp;

	/* at least 12: "AAAAAAAA P\1\n" */
	while (*data++ != ' ')
		if (data > data_end - 12)
			return -1;

	/* Make sure we have a newline character within the packet boundaries
	 * because simple_strtoul parses until the first invalid character. */
	for (tmp = data; tmp <= data_end; tmp++)
		if (*tmp == '\n')
			break;
	if (tmp > data_end || *tmp != '\n')
		return -1;

	*ad_beg_p = data;
	*ip = cpu_to_be32(simple_strtoul(data, &data, 10));

	/* skip blanks between ip and port */
	while (*data == ' ') {
		if (data >= data_end)
			return -1;
		data++;
	}

	*port = simple_strtoul(data, &data, 10);
	*ad_end_p = data;

	return 0;
}

static int help(struct sk_buff *skb, unsigned int protoff,
		struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff;
	const struct iphdr *iph;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	const char *data_limit;
	char *data, *ib_ptr;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	__be32 dcc_ip;
	u_int16_t dcc_port;
	__be16 port;
	int i, ret = NF_ACCEPT;
	char *addr_beg_p, *addr_end_p;
	typeof(nf_nat_irc_hook) nf_nat_irc;

	/* If packet is coming from IRC server */
	if (dir == IP_CT_DIR_REPLY)
		return NF_ACCEPT;

	/* 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;

	spin_lock_bh(&irc_buffer_lock);
	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
				    irc_buffer);
	BUG_ON(ib_ptr == NULL);

	data = ib_ptr;
	data_limit = ib_ptr + skb->len - dataoff;

	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	while (data < data_limit - (19 + MINMATCHLEN)) {
		if (memcmp(data, "\1DCC ", 5)) {
			data++;
			continue;
		}
		data += 5;
		/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */

		iph = ip_hdr(skb);
		pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
			 &iph->saddr, ntohs(th->source),
			 &iph->daddr, ntohs(th->dest));

		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
				/* no match */
				continue;
			}
			data += strlen(dccprotos[i]);
			pr_debug("DCC %s detected\n", dccprotos[i]);

			/* we have at least
			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
			 * data left (== 14/13 bytes) */
			if (parse_dcc(data, data_limit, &dcc_ip,
				       &dcc_port, &addr_beg_p, &addr_end_p)) {
				pr_debug("unable to parse dcc command\n");
				continue;
			}

			pr_debug("DCC bound ip/port: %pI4:%u\n",
				 &dcc_ip, dcc_port);

			/* dcc_ip can be the internal OR external (NAT'ed) IP */
			tuple = &ct->tuplehash[dir].tuple;
			if (tuple->src.u3.ip != dcc_ip &&
			    tuple->dst.u3.ip != dcc_ip) {
				if (net_ratelimit())
					printk(KERN_WARNING
						"Forged DCC command from %pI4: %pI4:%u\n",
						&tuple->src.u3.ip,
						&dcc_ip, dcc_port);
				continue;
			}

			exp = nf_ct_expect_alloc(ct);
			if (exp == NULL) {
				ret = NF_DROP;
				goto out;
			}
			tuple = &ct->tuplehash[!dir].tuple;
			port = htons(dcc_port);
			nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
					  tuple->src.l3num,
					  NULL, &tuple->dst.u3,
					  IPPROTO_TCP, NULL, &port);

			nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
			if (nf_nat_irc && ct->status & IPS_NAT_MASK)
				ret = nf_nat_irc(skb, ctinfo,
						 addr_beg_p - ib_ptr,
						 addr_end_p - addr_beg_p,
						 exp);
			else if (nf_ct_expect_related(exp) != 0)
				ret = NF_DROP;
			nf_ct_expect_put(exp);
			goto out;
		}
	}
 out:
	spin_unlock_bh(&irc_buffer_lock);
	return ret;
}

static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
static struct nf_conntrack_expect_policy irc_exp_policy;

static void nf_conntrack_irc_fini(void);

static int __init nf_conntrack_irc_init(void)
{
	int i, ret;
	char *tmpname;

	if (max_dcc_channels < 1) {
		printk("nf_ct_irc: max_dcc_channels must not be zero\n");
		return -EINVAL;
	}

	irc_exp_policy.max_expected = max_dcc_channels;
	irc_exp_policy.timeout = dcc_timeout;

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

	/* If no port given, default to standard irc port */
	if (ports_c == 0)
		ports[ports_c++] = IRC_PORT;

	for (i = 0; i < ports_c; i++) {
		irc[i].tuple.src.l3num = AF_INET;
		irc[i].tuple.src.u.tcp.port = htons(ports[i]);
		irc[i].tuple.dst.protonum = IPPROTO_TCP;
		irc[i].expect_policy = &irc_exp_policy;
		irc[i].me = THIS_MODULE;
		irc[i].help = help;

		tmpname = &irc_names[i][0];
		if (ports[i] == IRC_PORT)
			sprintf(tmpname, "irc");
		else
			sprintf(tmpname, "irc-%u", i);
		irc[i].name = tmpname;

		ret = nf_conntrack_helper_register(&irc[i]);
		if (ret) {
			printk("nf_ct_irc: failed to register helper "
			       "for pf: %u port: %u\n",
			       irc[i].tuple.src.l3num, ports[i]);
			nf_conntrack_irc_fini();
			return ret;
		}
	}
	return 0;
}

/* This function is intentionally _NOT_ defined as __exit, because
 * it is needed by the init function */
static void nf_conntrack_irc_fini(void)
{
	int i;

	for (i = 0; i < ports_c; i++)
		nf_conntrack_helper_unregister(&irc[i]);
	kfree(irc_buffer);
}

module_init(nf_conntrack_irc_init);
module_exit(nf_conntrack_irc_fini);
Commit	Line	Data
869f37d8 PM	1	/* IRC extension for IP connection tracking, Version 1.21
	2	* (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
	3	* based on RR's ip_conntrack_ftp.c
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License
	7	* as published by the Free Software Foundation; either version
	8	* 2 of the License, or (at your option) any later version.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/moduleparam.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/in.h>
0d53778e	15	#include <linux/ip.h>
869f37d8 PM	16	#include <linux/tcp.h>
	17	#include <linux/netfilter.h>
	18
	19	#include <net/netfilter/nf_conntrack.h>
	20	#include <net/netfilter/nf_conntrack_expect.h>
	21	#include <net/netfilter/nf_conntrack_helper.h>
	22	#include <linux/netfilter/nf_conntrack_irc.h>
	23
	24	#define MAX_PORTS 8
	25	static unsigned short ports[MAX_PORTS];
2f0d2f10	26	static unsigned int ports_c;
869f37d8 PM	27	static unsigned int max_dcc_channels = 8;
	28	static unsigned int dcc_timeout __read_mostly = 300;
	29	/* This is slow, but it's simple. --RR */
	30	static char *irc_buffer;
	31	static DEFINE_SPINLOCK(irc_buffer_lock);
	32
3db05fea	33	unsigned int (nf_nat_irc_hook)(struct sk_buff skb,
869f37d8 PM	34	enum ip_conntrack_info ctinfo,
	35	unsigned int matchoff,
	36	unsigned int matchlen,
	37	struct nf_conntrack_expect *exp) __read_mostly;
	38	EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
	39
	40	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	41	MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
	42	MODULE_LICENSE("GPL");
	43	MODULE_ALIAS("ip_conntrack_irc");
4dc06f96	44	MODULE_ALIAS_NFCT_HELPER("irc");
869f37d8 PM	45
	46	module_param_array(ports, ushort, &ports_c, 0400);
	47	MODULE_PARM_DESC(ports, "port numbers of IRC servers");
	48	module_param(max_dcc_channels, uint, 0400);
	49	MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
	50	"IRC session");
	51	module_param(dcc_timeout, uint, 0400);
	52	MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
	53
58c0fb0d	54	static const char *const dccprotos[] = {
869f37d8 PM	55	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
	56	};
	57
	58	#define MINMATCHLEN 5
	59
869f37d8 PM	60	/* tries to get the ip_addr and port out of a dcc command
	61	* return value: -1 on failure, 0 on success
	62	* data pointer to first byte of DCC command data
	63	* data_end pointer to last byte of dcc command data
	64	* ip returns parsed ip of dcc command
	65	* port returns parsed port of dcc command
	66	* ad_beg_p returns pointer to first byte of addr data
	67	* ad_end_p returns pointer to last byte of addr data
	68	*/
f9409649	69	static int parse_dcc(char data, const char data_end, __be32 *ip,
869f37d8 PM	70	u_int16_t port, char ad_beg_p, char *ad_end_p)
869f37d8 PM	71	{
e3b802ba PM	72	char *tmp;
e3b802ba PM	73
869f37d8 PM	74	/* at least 12: "AAAAAAAA P\1\n" */
	75	while (*data++ != ' ')
	76	if (data > data_end - 12)
	77	return -1;
	78
e3b802ba PM	79	/* Make sure we have a newline character within the packet boundaries
	80	* because simple_strtoul parses until the first invalid character. */
	81	for (tmp = data; tmp <= data_end; tmp++)
	82	if (*tmp == '\n')
	83	break;
	84	if (tmp > data_end \|\| *tmp != '\n')
	85	return -1;
	86
869f37d8	87	*ad_beg_p = data;
f9409649	88	*ip = cpu_to_be32(simple_strtoul(data, &data, 10));
869f37d8 PM	89
	90	/* skip blanks between ip and port */
	91	while (*data == ' ') {
	92	if (data >= data_end)
	93	return -1;
	94	data++;
	95	}
	96
	97	*port = simple_strtoul(data, &data, 10);
	98	*ad_end_p = data;
	99
	100	return 0;
	101	}
	102
3db05fea	103	static int help(struct sk_buff *skb, unsigned int protoff,
869f37d8 PM	104	struct nf_conn *ct, enum ip_conntrack_info ctinfo)
	105	{
	106	unsigned int dataoff;
58c0fb0d JE	107	const struct iphdr *iph;
	108	const struct tcphdr *th;
	109	struct tcphdr _tcph;
	110	const char *data_limit;
	111	char data, ib_ptr;
869f37d8 PM	112	int dir = CTINFO2DIR(ctinfo);
	113	struct nf_conntrack_expect *exp;
	114	struct nf_conntrack_tuple *tuple;
f9409649	115	__be32 dcc_ip;
869f37d8 PM	116	u_int16_t dcc_port;
	117	__be16 port;
	118	int i, ret = NF_ACCEPT;
	119	char addr_beg_p, addr_end_p;
	120	typeof(nf_nat_irc_hook) nf_nat_irc;
	121
	122	/* If packet is coming from IRC server */
	123	if (dir == IP_CT_DIR_REPLY)
	124	return NF_ACCEPT;
	125
	126	/* Until there's been traffic both ways, don't look in packets. */
	127	if (ctinfo != IP_CT_ESTABLISHED &&
	128	ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
	129	return NF_ACCEPT;
	130
	131	/* Not a full tcp header? */
3db05fea	132	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
869f37d8 PM	133	if (th == NULL)
	134	return NF_ACCEPT;
	135
	136	/* No data? */
	137	dataoff = protoff + th->doff*4;
3db05fea	138	if (dataoff >= skb->len)
869f37d8 PM	139	return NF_ACCEPT;
	140
	141	spin_lock_bh(&irc_buffer_lock);
3db05fea	142	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
869f37d8 PM	143	irc_buffer);
	144	BUG_ON(ib_ptr == NULL);
	145
	146	data = ib_ptr;
3db05fea	147	data_limit = ib_ptr + skb->len - dataoff;
869f37d8 PM	148
	149	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	150	* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	151	while (data < data_limit - (19 + MINMATCHLEN)) {
	152	if (memcmp(data, "\1DCC ", 5)) {
	153	data++;
	154	continue;
	155	}
	156	data += 5;
	157	/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
	158
3db05fea	159	iph = ip_hdr(skb);
14d5e834 HH	160	pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
	161	&iph->saddr, ntohs(th->source),
	162	&iph->daddr, ntohs(th->dest));
869f37d8 PM	163
	164	for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
	165	if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
	166	/* no match */
	167	continue;
	168	}
	169	data += strlen(dccprotos[i]);
0d53778e	170	pr_debug("DCC %s detected\n", dccprotos[i]);
869f37d8 PM	171
	172	/* we have at least
	173	* (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
	174	* data left (== 14/13 bytes) */
58c0fb0d	175	if (parse_dcc(data, data_limit, &dcc_ip,
869f37d8	176	&dcc_port, &addr_beg_p, &addr_end_p)) {
0d53778e	177	pr_debug("unable to parse dcc command\n");
869f37d8 PM	178	continue;
869f37d8 PM	179	}
f9409649 HH	180
	181	pr_debug("DCC bound ip/port: %pI4:%u\n",
	182	&dcc_ip, dcc_port);
869f37d8 PM	183
	184	/* dcc_ip can be the internal OR external (NAT'ed) IP */
	185	tuple = &ct->tuplehash[dir].tuple;
f9409649 HH	186	if (tuple->src.u3.ip != dcc_ip &&
f9409649 HH	187	tuple->dst.u3.ip != dcc_ip) {
869f37d8 PM	188	if (net_ratelimit())
869f37d8 PM	189	printk(KERN_WARNING
14d5e834 HH	190	"Forged DCC command from %pI4: %pI4:%u\n",
	191	&tuple->src.u3.ip,
	192	&dcc_ip, dcc_port);
869f37d8 PM	193	continue;
	194	}
	195
6823645d	196	exp = nf_ct_expect_alloc(ct);
869f37d8 PM	197	if (exp == NULL) {
	198	ret = NF_DROP;
	199	goto out;
	200	}
	201	tuple = &ct->tuplehash[!dir].tuple;
	202	port = htons(dcc_port);
6002f266 PM	203	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
6002f266 PM	204	tuple->src.l3num,
6823645d PM	205	NULL, &tuple->dst.u3,
6823645d PM	206	IPPROTO_TCP, NULL, &port);
869f37d8 PM	207
	208	nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
	209	if (nf_nat_irc && ct->status & IPS_NAT_MASK)
3db05fea	210	ret = nf_nat_irc(skb, ctinfo,
869f37d8 PM	211	addr_beg_p - ib_ptr,
	212	addr_end_p - addr_beg_p,
	213	exp);
6823645d	214	else if (nf_ct_expect_related(exp) != 0)
869f37d8	215	ret = NF_DROP;
6823645d	216	nf_ct_expect_put(exp);
869f37d8 PM	217	goto out;
	218	}
	219	}
	220	out:
	221	spin_unlock_bh(&irc_buffer_lock);
	222	return ret;
	223	}
	224
	225	static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
	226	static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
6002f266	227	static struct nf_conntrack_expect_policy irc_exp_policy;
869f37d8 PM	228
	229	static void nf_conntrack_irc_fini(void);
	230
	231	static int __init nf_conntrack_irc_init(void)
	232	{
	233	int i, ret;
	234	char *tmpname;
	235
	236	if (max_dcc_channels < 1) {
	237	printk("nf_ct_irc: max_dcc_channels must not be zero\n");
	238	return -EINVAL;
	239	}
	240
6002f266 PM	241	irc_exp_policy.max_expected = max_dcc_channels;
	242	irc_exp_policy.timeout = dcc_timeout;
	243
869f37d8 PM	244	irc_buffer = kmalloc(65536, GFP_KERNEL);
	245	if (!irc_buffer)
	246	return -ENOMEM;
	247
	248	/* If no port given, default to standard irc port */
	249	if (ports_c == 0)
	250	ports[ports_c++] = IRC_PORT;
	251
	252	for (i = 0; i < ports_c; i++) {
	253	irc[i].tuple.src.l3num = AF_INET;
	254	irc[i].tuple.src.u.tcp.port = htons(ports[i]);
	255	irc[i].tuple.dst.protonum = IPPROTO_TCP;
6002f266	256	irc[i].expect_policy = &irc_exp_policy;
869f37d8 PM	257	irc[i].me = THIS_MODULE;
	258	irc[i].help = help;
	259
	260	tmpname = &irc_names[i][0];
	261	if (ports[i] == IRC_PORT)
	262	sprintf(tmpname, "irc");
	263	else
	264	sprintf(tmpname, "irc-%u", i);
	265	irc[i].name = tmpname;
	266
	267	ret = nf_conntrack_helper_register(&irc[i]);
	268	if (ret) {
	269	printk("nf_ct_irc: failed to register helper "
	270	"for pf: %u port: %u\n",
	271	irc[i].tuple.src.l3num, ports[i]);
	272	nf_conntrack_irc_fini();
	273	return ret;
	274	}
	275	}
	276	return 0;
	277	}
	278
	279	/* This function is intentionally _NOT_ defined as __exit, because
	280	* it is needed by the init function */
	281	static void nf_conntrack_irc_fini(void)
	282	{
	283	int i;
	284
	285	for (i = 0; i < ports_c; i++)
	286	nf_conntrack_helper_unregister(&irc[i]);
	287	kfree(irc_buffer);
	288	}
	289
	290	module_init(nf_conntrack_irc_init);
	291	module_exit(nf_conntrack_irc_fini);