[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 <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_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, u_int32_t *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 = 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;
	u_int32_t 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 %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n",
			 NIPQUAD(iph->saddr), ntohs(th->source),
			 NIPQUAD(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: %u.%u.%u.%u:%u\n",
				 HIPQUAD(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 != htonl(dcc_ip) &&
			    tuple->dst.u3.ip != htonl(dcc_ip)) {
				if (net_ratelimit())
					printk(KERN_WARNING
						"Forged DCC command from "
						"%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
						NIPQUAD(tuple->src.u3.ip),
						HIPQUAD(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");
	44
	45	module_param_array(ports, ushort, &ports_c, 0400);
	46	MODULE_PARM_DESC(ports, "port numbers of IRC servers");
	47	module_param(max_dcc_channels, uint, 0400);
	48	MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
	49	"IRC session");
	50	module_param(dcc_timeout, uint, 0400);
	51	MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
	52
58c0fb0d	53	static const char *const dccprotos[] = {
869f37d8 PM	54	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
	55	};
	56
	57	#define MINMATCHLEN 5
	58
869f37d8 PM	59	/* tries to get the ip_addr and port out of a dcc command
	60	* return value: -1 on failure, 0 on success
	61	* data pointer to first byte of DCC command data
	62	* data_end pointer to last byte of dcc command data
	63	* ip returns parsed ip of dcc command
	64	* port returns parsed port of dcc command
	65	* ad_beg_p returns pointer to first byte of addr data
	66	* ad_end_p returns pointer to last byte of addr data
	67	*/
58c0fb0d	68	static int parse_dcc(char data, const char data_end, u_int32_t *ip,
869f37d8 PM	69	u_int16_t port, char ad_beg_p, char *ad_end_p)
869f37d8 PM	70	{
e3b802ba PM	71	char *tmp;
e3b802ba PM	72
869f37d8 PM	73	/* at least 12: "AAAAAAAA P\1\n" */
	74	while (*data++ != ' ')
	75	if (data > data_end - 12)
	76	return -1;
	77
e3b802ba PM	78	/* Make sure we have a newline character within the packet boundaries
	79	* because simple_strtoul parses until the first invalid character. */
	80	for (tmp = data; tmp <= data_end; tmp++)
	81	if (*tmp == '\n')
	82	break;
	83	if (tmp > data_end \|\| *tmp != '\n')
	84	return -1;
	85
869f37d8 PM	86	*ad_beg_p = data;
	87	*ip = simple_strtoul(data, &data, 10);
	88
	89	/* skip blanks between ip and port */
	90	while (*data == ' ') {
	91	if (data >= data_end)
	92	return -1;
	93	data++;
	94	}
	95
	96	*port = simple_strtoul(data, &data, 10);
	97	*ad_end_p = data;
	98
	99	return 0;
	100	}
	101
3db05fea	102	static int help(struct sk_buff *skb, unsigned int protoff,
869f37d8 PM	103	struct nf_conn *ct, enum ip_conntrack_info ctinfo)
	104	{
	105	unsigned int dataoff;
58c0fb0d JE	106	const struct iphdr *iph;
	107	const struct tcphdr *th;
	108	struct tcphdr _tcph;
	109	const char *data_limit;
	110	char data, ib_ptr;
869f37d8 PM	111	int dir = CTINFO2DIR(ctinfo);
	112	struct nf_conntrack_expect *exp;
	113	struct nf_conntrack_tuple *tuple;
	114	u_int32_t dcc_ip;
	115	u_int16_t dcc_port;
	116	__be16 port;
	117	int i, ret = NF_ACCEPT;
	118	char addr_beg_p, addr_end_p;
	119	typeof(nf_nat_irc_hook) nf_nat_irc;
	120
	121	/* If packet is coming from IRC server */
	122	if (dir == IP_CT_DIR_REPLY)
	123	return NF_ACCEPT;
	124
	125	/* Until there's been traffic both ways, don't look in packets. */
	126	if (ctinfo != IP_CT_ESTABLISHED &&
	127	ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
	128	return NF_ACCEPT;
	129
	130	/* Not a full tcp header? */
3db05fea	131	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
869f37d8 PM	132	if (th == NULL)
	133	return NF_ACCEPT;
	134
	135	/* No data? */
	136	dataoff = protoff + th->doff*4;
3db05fea	137	if (dataoff >= skb->len)
869f37d8 PM	138	return NF_ACCEPT;
	139
	140	spin_lock_bh(&irc_buffer_lock);
3db05fea	141	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
869f37d8 PM	142	irc_buffer);
	143	BUG_ON(ib_ptr == NULL);
	144
	145	data = ib_ptr;
3db05fea	146	data_limit = ib_ptr + skb->len - dataoff;
869f37d8 PM	147
	148	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	149	* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	150	while (data < data_limit - (19 + MINMATCHLEN)) {
	151	if (memcmp(data, "\1DCC ", 5)) {
	152	data++;
	153	continue;
	154	}
	155	data += 5;
	156	/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
	157
3db05fea	158	iph = ip_hdr(skb);
0d53778e PM	159	pr_debug("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n",
	160	NIPQUAD(iph->saddr), ntohs(th->source),
	161	NIPQUAD(iph->daddr), ntohs(th->dest));
869f37d8 PM	162
	163	for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
	164	if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
	165	/* no match */
	166	continue;
	167	}
	168	data += strlen(dccprotos[i]);
0d53778e	169	pr_debug("DCC %s detected\n", dccprotos[i]);
869f37d8 PM	170
	171	/* we have at least
	172	* (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
	173	* data left (== 14/13 bytes) */
58c0fb0d	174	if (parse_dcc(data, data_limit, &dcc_ip,
869f37d8	175	&dcc_port, &addr_beg_p, &addr_end_p)) {
0d53778e	176	pr_debug("unable to parse dcc command\n");
869f37d8 PM	177	continue;
869f37d8 PM	178	}
0d53778e PM	179	pr_debug("DCC bound ip/port: %u.%u.%u.%u:%u\n",
0d53778e PM	180	HIPQUAD(dcc_ip), dcc_port);
869f37d8 PM	181
	182	/* dcc_ip can be the internal OR external (NAT'ed) IP */
	183	tuple = &ct->tuplehash[dir].tuple;
	184	if (tuple->src.u3.ip != htonl(dcc_ip) &&
	185	tuple->dst.u3.ip != htonl(dcc_ip)) {
	186	if (net_ratelimit())
	187	printk(KERN_WARNING
	188	"Forged DCC command from "
	189	"%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
	190	NIPQUAD(tuple->src.u3.ip),
	191	HIPQUAD(dcc_ip), dcc_port);
	192	continue;
	193	}
	194
6823645d	195	exp = nf_ct_expect_alloc(ct);
869f37d8 PM	196	if (exp == NULL) {
	197	ret = NF_DROP;
	198	goto out;
	199	}
	200	tuple = &ct->tuplehash[!dir].tuple;
	201	port = htons(dcc_port);
6002f266 PM	202	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
6002f266 PM	203	tuple->src.l3num,
6823645d PM	204	NULL, &tuple->dst.u3,
6823645d PM	205	IPPROTO_TCP, NULL, &port);
869f37d8 PM	206
	207	nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
	208	if (nf_nat_irc && ct->status & IPS_NAT_MASK)
3db05fea	209	ret = nf_nat_irc(skb, ctinfo,
869f37d8 PM	210	addr_beg_p - ib_ptr,
	211	addr_end_p - addr_beg_p,
	212	exp);
6823645d	213	else if (nf_ct_expect_related(exp) != 0)
869f37d8	214	ret = NF_DROP;
6823645d	215	nf_ct_expect_put(exp);
869f37d8 PM	216	goto out;
	217	}
	218	}
	219	out:
	220	spin_unlock_bh(&irc_buffer_lock);
	221	return ret;
	222	}
	223
	224	static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
	225	static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
6002f266	226	static struct nf_conntrack_expect_policy irc_exp_policy;
869f37d8 PM	227
	228	static void nf_conntrack_irc_fini(void);
	229
	230	static int __init nf_conntrack_irc_init(void)
	231	{
	232	int i, ret;
	233	char *tmpname;
	234
	235	if (max_dcc_channels < 1) {
	236	printk("nf_ct_irc: max_dcc_channels must not be zero\n");
	237	return -EINVAL;
	238	}
	239
6002f266 PM	240	irc_exp_policy.max_expected = max_dcc_channels;
	241	irc_exp_policy.timeout = dcc_timeout;
	242
869f37d8 PM	243	irc_buffer = kmalloc(65536, GFP_KERNEL);
	244	if (!irc_buffer)
	245	return -ENOMEM;
	246
	247	/* If no port given, default to standard irc port */
	248	if (ports_c == 0)
	249	ports[ports_c++] = IRC_PORT;
	250
	251	for (i = 0; i < ports_c; i++) {
	252	irc[i].tuple.src.l3num = AF_INET;
	253	irc[i].tuple.src.u.tcp.port = htons(ports[i]);
	254	irc[i].tuple.dst.protonum = IPPROTO_TCP;
6002f266	255	irc[i].expect_policy = &irc_exp_policy;
869f37d8 PM	256	irc[i].me = THIS_MODULE;
	257	irc[i].help = help;
	258
	259	tmpname = &irc_names[i][0];
	260	if (ports[i] == IRC_PORT)
	261	sprintf(tmpname, "irc");
	262	else
	263	sprintf(tmpname, "irc-%u", i);
	264	irc[i].name = tmpname;
	265
	266	ret = nf_conntrack_helper_register(&irc[i]);
	267	if (ret) {
	268	printk("nf_ct_irc: failed to register helper "
	269	"for pf: %u port: %u\n",
	270	irc[i].tuple.src.l3num, ports[i]);
	271	nf_conntrack_irc_fini();
	272	return ret;
	273	}
	274	}
	275	return 0;
	276	}
	277
	278	/* This function is intentionally _NOT_ defined as __exit, because
	279	* it is needed by the init function */
	280	static void nf_conntrack_irc_fini(void)
	281	{
	282	int i;
	283
	284	for (i = 0; i < ports_c; i++)
	285	nf_conntrack_helper_unregister(&irc[i]);
	286	kfree(irc_buffer);
	287	}
	288
	289	module_init(nf_conntrack_irc_init);
	290	module_exit(nf_conntrack_irc_fini);