[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 protoff,
				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) {
				nf_ct_helper_log(skb, ct,
						 "cannot alloc expectation");
				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, protoff,
						 addr_beg_p - ib_ptr,
						 addr_end_p - addr_beg_p,
						 exp);
			else if (nf_ct_expect_related(exp) != 0) {
				nf_ct_helper_log(skb, ct,
						 "cannot add expectation");
				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 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;

	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;

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

		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	35	enum ip_conntrack_info ctinfo,
051966c0	36	unsigned int protoff,
869f37d8 PM	37	unsigned int matchoff,
	38	unsigned int matchlen,
	39	struct nf_conntrack_expect *exp) __read_mostly;
	40	EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
	41
	42	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	43	MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
	44	MODULE_LICENSE("GPL");
	45	MODULE_ALIAS("ip_conntrack_irc");
4dc06f96	46	MODULE_ALIAS_NFCT_HELPER("irc");
869f37d8 PM	47
	48	module_param_array(ports, ushort, &ports_c, 0400);
	49	MODULE_PARM_DESC(ports, "port numbers of IRC servers");
	50	module_param(max_dcc_channels, uint, 0400);
	51	MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
	52	"IRC session");
	53	module_param(dcc_timeout, uint, 0400);
	54	MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
	55
58c0fb0d	56	static const char *const dccprotos[] = {
869f37d8 PM	57	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
	58	};
	59
	60	#define MINMATCHLEN 5
	61
869f37d8 PM	62	/* tries to get the ip_addr and port out of a dcc command
	63	* return value: -1 on failure, 0 on success
	64	* data pointer to first byte of DCC command data
	65	* data_end pointer to last byte of dcc command data
	66	* ip returns parsed ip of dcc command
	67	* port returns parsed port of dcc command
	68	* ad_beg_p returns pointer to first byte of addr data
	69	* ad_end_p returns pointer to last byte of addr data
	70	*/
f9409649	71	static int parse_dcc(char data, const char data_end, __be32 *ip,
869f37d8 PM	72	u_int16_t port, char ad_beg_p, char *ad_end_p)
869f37d8 PM	73	{
e3b802ba PM	74	char *tmp;
e3b802ba PM	75
869f37d8 PM	76	/* at least 12: "AAAAAAAA P\1\n" */
	77	while (*data++ != ' ')
	78	if (data > data_end - 12)
	79	return -1;
	80
e3b802ba PM	81	/* Make sure we have a newline character within the packet boundaries
	82	* because simple_strtoul parses until the first invalid character. */
	83	for (tmp = data; tmp <= data_end; tmp++)
	84	if (*tmp == '\n')
	85	break;
	86	if (tmp > data_end \|\| *tmp != '\n')
	87	return -1;
	88
869f37d8	89	*ad_beg_p = data;
f9409649	90	*ip = cpu_to_be32(simple_strtoul(data, &data, 10));
869f37d8 PM	91
	92	/* skip blanks between ip and port */
	93	while (*data == ' ') {
	94	if (data >= data_end)
	95	return -1;
	96	data++;
	97	}
	98
	99	*port = simple_strtoul(data, &data, 10);
	100	*ad_end_p = data;
	101
	102	return 0;
	103	}
	104
3db05fea	105	static int help(struct sk_buff *skb, unsigned int protoff,
869f37d8 PM	106	struct nf_conn *ct, enum ip_conntrack_info ctinfo)
	107	{
	108	unsigned int dataoff;
58c0fb0d JE	109	const struct iphdr *iph;
	110	const struct tcphdr *th;
	111	struct tcphdr _tcph;
	112	const char *data_limit;
	113	char data, ib_ptr;
869f37d8 PM	114	int dir = CTINFO2DIR(ctinfo);
	115	struct nf_conntrack_expect *exp;
	116	struct nf_conntrack_tuple *tuple;
f9409649	117	__be32 dcc_ip;
869f37d8 PM	118	u_int16_t dcc_port;
	119	__be16 port;
	120	int i, ret = NF_ACCEPT;
	121	char addr_beg_p, addr_end_p;
	122	typeof(nf_nat_irc_hook) nf_nat_irc;
	123
	124	/* If packet is coming from IRC server */
	125	if (dir == IP_CT_DIR_REPLY)
	126	return NF_ACCEPT;
	127
	128	/* Until there's been traffic both ways, don't look in packets. */
fb048833	129	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
869f37d8 PM	130	return NF_ACCEPT;
	131
	132	/* Not a full tcp header? */
3db05fea	133	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
869f37d8 PM	134	if (th == NULL)
	135	return NF_ACCEPT;
	136
	137	/* No data? */
	138	dataoff = protoff + th->doff*4;
3db05fea	139	if (dataoff >= skb->len)
869f37d8 PM	140	return NF_ACCEPT;
	141
	142	spin_lock_bh(&irc_buffer_lock);
3db05fea	143	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
869f37d8 PM	144	irc_buffer);
	145	BUG_ON(ib_ptr == NULL);
	146
	147	data = ib_ptr;
3db05fea	148	data_limit = ib_ptr + skb->len - dataoff;
869f37d8 PM	149
	150	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	151	* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	152	while (data < data_limit - (19 + MINMATCHLEN)) {
	153	if (memcmp(data, "\1DCC ", 5)) {
	154	data++;
	155	continue;
	156	}
	157	data += 5;
	158	/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
	159
3db05fea	160	iph = ip_hdr(skb);
14d5e834 HH	161	pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
	162	&iph->saddr, ntohs(th->source),
	163	&iph->daddr, ntohs(th->dest));
869f37d8 PM	164
	165	for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
	166	if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
	167	/* no match */
	168	continue;
	169	}
	170	data += strlen(dccprotos[i]);
0d53778e	171	pr_debug("DCC %s detected\n", dccprotos[i]);
869f37d8 PM	172
	173	/* we have at least
	174	* (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
	175	* data left (== 14/13 bytes) */
58c0fb0d	176	if (parse_dcc(data, data_limit, &dcc_ip,
869f37d8	177	&dcc_port, &addr_beg_p, &addr_end_p)) {
0d53778e	178	pr_debug("unable to parse dcc command\n");
869f37d8 PM	179	continue;
869f37d8 PM	180	}
f9409649 HH	181
	182	pr_debug("DCC bound ip/port: %pI4:%u\n",
	183	&dcc_ip, dcc_port);
869f37d8 PM	184
	185	/* dcc_ip can be the internal OR external (NAT'ed) IP */
	186	tuple = &ct->tuplehash[dir].tuple;
f9409649 HH	187	if (tuple->src.u3.ip != dcc_ip &&
f9409649 HH	188	tuple->dst.u3.ip != dcc_ip) {
e87cc472 JP	189	net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
	190	&tuple->src.u3.ip,
	191	&dcc_ip, dcc_port);
869f37d8 PM	192	continue;
	193	}
	194
6823645d	195	exp = nf_ct_expect_alloc(ct);
869f37d8	196	if (exp == NULL) {
b20ab9cc PNA	197	nf_ct_helper_log(skb, ct,
b20ab9cc PNA	198	"cannot alloc expectation");
869f37d8 PM	199	ret = NF_DROP;
	200	goto out;
	201	}
	202	tuple = &ct->tuplehash[!dir].tuple;
	203	port = htons(dcc_port);
6002f266 PM	204	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
6002f266 PM	205	tuple->src.l3num,
6823645d PM	206	NULL, &tuple->dst.u3,
6823645d PM	207	IPPROTO_TCP, NULL, &port);
869f37d8 PM	208
869f37d8 PM	209	nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
5901b6be	210	if (nf_nat_irc && ct->status & IPS_NAT_MASK)
051966c0	211	ret = nf_nat_irc(skb, ctinfo, protoff,
869f37d8 PM	212	addr_beg_p - ib_ptr,
	213	addr_end_p - addr_beg_p,
	214	exp);
b20ab9cc PNA	215	else if (nf_ct_expect_related(exp) != 0) {
	216	nf_ct_helper_log(skb, ct,
	217	"cannot add expectation");
869f37d8	218	ret = NF_DROP;
b20ab9cc	219	}
6823645d	220	nf_ct_expect_put(exp);
869f37d8 PM	221	goto out;
	222	}
	223	}
	224	out:
	225	spin_unlock_bh(&irc_buffer_lock);
	226	return ret;
	227	}
	228
	229	static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
6002f266	230	static struct nf_conntrack_expect_policy irc_exp_policy;
869f37d8 PM	231
	232	static void nf_conntrack_irc_fini(void);
	233
	234	static int __init nf_conntrack_irc_init(void)
	235	{
	236	int i, ret;
869f37d8 PM	237
869f37d8 PM	238	if (max_dcc_channels < 1) {
654d0fbd	239	printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n");
869f37d8 PM	240	return -EINVAL;
	241	}
	242
6002f266 PM	243	irc_exp_policy.max_expected = max_dcc_channels;
	244	irc_exp_policy.timeout = dcc_timeout;
	245
869f37d8 PM	246	irc_buffer = kmalloc(65536, GFP_KERNEL);
	247	if (!irc_buffer)
	248	return -ENOMEM;
	249
	250	/* If no port given, default to standard irc port */
	251	if (ports_c == 0)
	252	ports[ports_c++] = IRC_PORT;
	253
	254	for (i = 0; i < ports_c; i++) {
	255	irc[i].tuple.src.l3num = AF_INET;
	256	irc[i].tuple.src.u.tcp.port = htons(ports[i]);
	257	irc[i].tuple.dst.protonum = IPPROTO_TCP;
6002f266	258	irc[i].expect_policy = &irc_exp_policy;
869f37d8 PM	259	irc[i].me = THIS_MODULE;
	260	irc[i].help = help;
	261
869f37d8	262	if (ports[i] == IRC_PORT)
3a8fc53a	263	sprintf(irc[i].name, "irc");
869f37d8	264	else
3a8fc53a	265	sprintf(irc[i].name, "irc-%u", i);
869f37d8 PM	266
	267	ret = nf_conntrack_helper_register(&irc[i]);
	268	if (ret) {
654d0fbd	269	printk(KERN_ERR "nf_ct_irc: failed to register helper "
869f37d8 PM	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);