[deliverable/linux.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 <linux/slab.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_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) {
				net_warn_ratelimited("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(KERN_ERR "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(KERN_ERR "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>
869f37d8 PM	17	#include <linux/netfilter.h>
5a0e3ad6	18	#include <linux/slab.h>
869f37d8 PM	19
	20	#include <net/netfilter/nf_conntrack.h>
	21	#include <net/netfilter/nf_conntrack_expect.h>
	22	#include <net/netfilter/nf_conntrack_helper.h>
	23	#include <linux/netfilter/nf_conntrack_irc.h>
	24
	25	#define MAX_PORTS 8
	26	static unsigned short ports[MAX_PORTS];
2f0d2f10	27	static unsigned int ports_c;
869f37d8 PM	28	static unsigned int max_dcc_channels = 8;
	29	static unsigned int dcc_timeout __read_mostly = 300;
	30	/* This is slow, but it's simple. --RR */
	31	static char *irc_buffer;
	32	static DEFINE_SPINLOCK(irc_buffer_lock);
	33
3db05fea	34	unsigned int (nf_nat_irc_hook)(struct sk_buff skb,
869f37d8 PM	35	enum ip_conntrack_info ctinfo,
	36	unsigned int matchoff,
	37	unsigned int matchlen,
	38	struct nf_conntrack_expect *exp) __read_mostly;
	39	EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
	40
	41	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	42	MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
	43	MODULE_LICENSE("GPL");
	44	MODULE_ALIAS("ip_conntrack_irc");
4dc06f96	45	MODULE_ALIAS_NFCT_HELPER("irc");
869f37d8 PM	46
	47	module_param_array(ports, ushort, &ports_c, 0400);
	48	MODULE_PARM_DESC(ports, "port numbers of IRC servers");
	49	module_param(max_dcc_channels, uint, 0400);
	50	MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
	51	"IRC session");
	52	module_param(dcc_timeout, uint, 0400);
	53	MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
	54
58c0fb0d	55	static const char *const dccprotos[] = {
869f37d8 PM	56	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
	57	};
	58
	59	#define MINMATCHLEN 5
	60
869f37d8 PM	61	/* tries to get the ip_addr and port out of a dcc command
	62	* return value: -1 on failure, 0 on success
	63	* data pointer to first byte of DCC command data
	64	* data_end pointer to last byte of dcc command data
	65	* ip returns parsed ip of dcc command
	66	* port returns parsed port of dcc command
	67	* ad_beg_p returns pointer to first byte of addr data
	68	* ad_end_p returns pointer to last byte of addr data
	69	*/
f9409649	70	static int parse_dcc(char data, const char data_end, __be32 *ip,
869f37d8 PM	71	u_int16_t port, char ad_beg_p, char *ad_end_p)
869f37d8 PM	72	{
e3b802ba PM	73	char *tmp;
e3b802ba PM	74
869f37d8 PM	75	/* at least 12: "AAAAAAAA P\1\n" */
	76	while (*data++ != ' ')
	77	if (data > data_end - 12)
	78	return -1;
	79
e3b802ba PM	80	/* Make sure we have a newline character within the packet boundaries
	81	* because simple_strtoul parses until the first invalid character. */
	82	for (tmp = data; tmp <= data_end; tmp++)
	83	if (*tmp == '\n')
	84	break;
	85	if (tmp > data_end \|\| *tmp != '\n')
	86	return -1;
	87
869f37d8	88	*ad_beg_p = data;
f9409649	89	*ip = cpu_to_be32(simple_strtoul(data, &data, 10));
869f37d8 PM	90
	91	/* skip blanks between ip and port */
	92	while (*data == ' ') {
	93	if (data >= data_end)
	94	return -1;
	95	data++;
	96	}
	97
	98	*port = simple_strtoul(data, &data, 10);
	99	*ad_end_p = data;
	100
	101	return 0;
	102	}
	103
3db05fea	104	static int help(struct sk_buff *skb, unsigned int protoff,
869f37d8 PM	105	struct nf_conn *ct, enum ip_conntrack_info ctinfo)
	106	{
	107	unsigned int dataoff;
58c0fb0d JE	108	const struct iphdr *iph;
	109	const struct tcphdr *th;
	110	struct tcphdr _tcph;
	111	const char *data_limit;
	112	char data, ib_ptr;
869f37d8 PM	113	int dir = CTINFO2DIR(ctinfo);
	114	struct nf_conntrack_expect *exp;
	115	struct nf_conntrack_tuple *tuple;
f9409649	116	__be32 dcc_ip;
869f37d8 PM	117	u_int16_t dcc_port;
	118	__be16 port;
	119	int i, ret = NF_ACCEPT;
	120	char addr_beg_p, addr_end_p;
	121	typeof(nf_nat_irc_hook) nf_nat_irc;
	122
	123	/* If packet is coming from IRC server */
	124	if (dir == IP_CT_DIR_REPLY)
	125	return NF_ACCEPT;
	126
	127	/* Until there's been traffic both ways, don't look in packets. */
fb048833	128	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
869f37d8 PM	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) {
e87cc472 JP	188	net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
	189	&tuple->src.u3.ip,
	190	&dcc_ip, dcc_port);
869f37d8 PM	191	continue;
	192	}
	193
6823645d	194	exp = nf_ct_expect_alloc(ct);
869f37d8 PM	195	if (exp == NULL) {
	196	ret = NF_DROP;
	197	goto out;
	198	}
	199	tuple = &ct->tuplehash[!dir].tuple;
	200	port = htons(dcc_port);
6002f266 PM	201	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
6002f266 PM	202	tuple->src.l3num,
6823645d PM	203	NULL, &tuple->dst.u3,
6823645d PM	204	IPPROTO_TCP, NULL, &port);
869f37d8 PM	205
	206	nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
	207	if (nf_nat_irc && ct->status & IPS_NAT_MASK)
3db05fea	208	ret = nf_nat_irc(skb, ctinfo,
869f37d8 PM	209	addr_beg_p - ib_ptr,
	210	addr_end_p - addr_beg_p,
	211	exp);
6823645d	212	else if (nf_ct_expect_related(exp) != 0)
869f37d8	213	ret = NF_DROP;
6823645d	214	nf_ct_expect_put(exp);
869f37d8 PM	215	goto out;
	216	}
	217	}
	218	out:
	219	spin_unlock_bh(&irc_buffer_lock);
	220	return ret;
	221	}
	222
	223	static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
	224	static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
6002f266	225	static struct nf_conntrack_expect_policy irc_exp_policy;
869f37d8 PM	226
	227	static void nf_conntrack_irc_fini(void);
	228
	229	static int __init nf_conntrack_irc_init(void)
	230	{
	231	int i, ret;
	232	char *tmpname;
	233
	234	if (max_dcc_channels < 1) {
654d0fbd	235	printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n");
869f37d8 PM	236	return -EINVAL;
	237	}
	238
6002f266 PM	239	irc_exp_policy.max_expected = max_dcc_channels;
	240	irc_exp_policy.timeout = dcc_timeout;
	241
869f37d8 PM	242	irc_buffer = kmalloc(65536, GFP_KERNEL);
	243	if (!irc_buffer)
	244	return -ENOMEM;
	245
	246	/* If no port given, default to standard irc port */
	247	if (ports_c == 0)
	248	ports[ports_c++] = IRC_PORT;
	249
	250	for (i = 0; i < ports_c; i++) {
	251	irc[i].tuple.src.l3num = AF_INET;
	252	irc[i].tuple.src.u.tcp.port = htons(ports[i]);
	253	irc[i].tuple.dst.protonum = IPPROTO_TCP;
6002f266	254	irc[i].expect_policy = &irc_exp_policy;
869f37d8 PM	255	irc[i].me = THIS_MODULE;
	256	irc[i].help = help;
	257
	258	tmpname = &irc_names[i][0];
	259	if (ports[i] == IRC_PORT)
	260	sprintf(tmpname, "irc");
	261	else
	262	sprintf(tmpname, "irc-%u", i);
	263	irc[i].name = tmpname;
	264
	265	ret = nf_conntrack_helper_register(&irc[i]);
	266	if (ret) {
654d0fbd	267	printk(KERN_ERR "nf_ct_irc: failed to register helper "
869f37d8 PM	268	"for pf: %u port: %u\n",
	269	irc[i].tuple.src.l3num, ports[i]);
	270	nf_conntrack_irc_fini();
	271	return ret;
	272	}
	273	}
	274	return 0;
	275	}
	276
	277	/* This function is intentionally _NOT_ defined as __exit, because
	278	* it is needed by the init function */
	279	static void nf_conntrack_irc_fini(void)
	280	{
	281	int i;
	282
	283	for (i = 0; i < ports_c; i++)
	284	nf_conntrack_helper_unregister(&irc[i]);
	285	kfree(irc_buffer);
	286	}
	287
	288	module_init(nf_conntrack_irc_init);
	289	module_exit(nf_conntrack_irc_fini);