net/ipv4/netfilter/ip_conntrack_irc.c - linux/kernel/git/klassert/ipsec-next - Git at Google

 /* 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
  *
  * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp
  *
  *      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.
  **
  *	Module load syntax:
  * 	insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS>
  *			    max_dcc_channels=n dcc_timeout=secs
  *
  * 	please give the ports of all IRC servers You wish to connect to.
  *	If You don't specify ports, the default will be port 6667.
  *	With max_dcc_channels you can define the maximum number of not
  *	yet answered DCC channels per IRC session (default 8).
  *	With dcc_timeout you can specify how long the system waits for
  *	an expected DCC channel (default 300 seconds).
  *
  */

 #include <linux/module.h>
 #include <linux/netfilter.h>
 #include <linux/ip.h>
 #include <net/checksum.h>
 #include <net/tcp.h>

 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
 #include <linux/netfilter_ipv4/ip_conntrack_irc.h>
 #include <linux/moduleparam.h>

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

 unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb,
 				enum ip_conntrack_info ctinfo,
 				unsigned int matchoff,
 				unsigned int matchlen,
 				struct ip_conntrack_expect *exp);
 EXPORT_SYMBOL_GPL(ip_nat_irc_hook);

 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
 MODULE_LICENSE("GPL");
 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 *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
 #define MINMATCHLEN	5

 #if 0
 #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \
                                        __FILE__, __FUNCTION__ , ## args)
 #else
 #define DEBUGP(format, args...)
 #endif

 static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
 		     u_int16_t *port, char **ad_beg_p, char **ad_end_p)
 /* 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 */
 {

 	/* at least 12: "AAAAAAAA P\1\n" */
 	while (*data++ != ' ')
 		if (data > data_end - 12)
 			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 **pskb,
 		struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
 {
 	unsigned int dataoff;
 	struct tcphdr _tcph, *th;
 	char *data, *data_limit, *ib_ptr;
 	int dir = CTINFO2DIR(ctinfo);
 	struct ip_conntrack_expect *exp;
 	u32 seq;
 	u_int32_t dcc_ip;
 	u_int16_t dcc_port;
 	int i, ret = NF_ACCEPT;
 	char *addr_beg_p, *addr_end_p;

 	DEBUGP("entered\n");

 	/* 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) {
 		DEBUGP("Conntrackinfo = %u\n", ctinfo);
 		return NF_ACCEPT;
 	}

 	/* Not a full tcp header? */
 	th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
 				sizeof(_tcph), &_tcph);
 	if (th == NULL)
 		return NF_ACCEPT;

 	/* No data? */
 	dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4;
 	if (dataoff >= (*pskb)->len)
 		return NF_ACCEPT;

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

 	data = ib_ptr;
 	data_limit = ib_ptr + (*pskb)->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 */

 		DEBUGP("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;
 			}

 			DEBUGP("DCC %s detected\n", dccprotos[i]);
 			data += strlen(dccprotos[i]);
 			/* we have at least
 			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
 			 * data left (== 14/13 bytes) */
 			if (parse_dcc((char *)data, data_limit, &dcc_ip,
 				       &dcc_port, &addr_beg_p, &addr_end_p)) {
 				/* unable to parse */
 				DEBUGP("unable to parse dcc command\n");
 				continue;
 			}
 			DEBUGP("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
 			 * Tiago Sousa <mirage@kaotik.org> */
 			if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
 			    && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.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(ct->tuplehash[dir].tuple.src.ip),
 						HIPQUAD(dcc_ip), dcc_port);

 				continue;
 			}

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

 			/* save position of address in dcc string,
 			 * necessary for NAT */
 			DEBUGP("tcph->seq = %u\n", th->seq);
 			seq = ntohl(th->seq) + (addr_beg_p - ib_ptr);

 			/* We refer to the reverse direction ("!dir")
 			 * tuples here, because we're expecting
 			 * something in the other * direction.
 			 * Doesn't matter unless NAT is happening.  */
 			exp->tuple = ((struct ip_conntrack_tuple)
 				{ { 0, { 0 } },
 				  { ct->tuplehash[!dir].tuple.dst.ip,
 				    { .tcp = { htons(dcc_port) } },
 				    IPPROTO_TCP }});
 			exp->mask = ((struct ip_conntrack_tuple)
 				{ { 0, { 0 } },
 				  { htonl(0xFFFFFFFF),
 					{ .tcp = { htons(0xFFFF) } }, 0xFF }});
 			exp->expectfn = NULL;
 			exp->flags = 0;
 			if (ip_nat_irc_hook)
 				ret = ip_nat_irc_hook(pskb, ctinfo,
 						      addr_beg_p - ib_ptr,
 						      addr_end_p - addr_beg_p,
 						      exp);
 			else if (ip_conntrack_expect_related(exp) != 0)
 				ret = NF_DROP;
 			ip_conntrack_expect_put(exp);
 			goto out;
 		} /* for .. NUM_DCCPROTO */
 	} /* while data < ... */

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

 static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
 static char irc_names[MAX_PORTS][sizeof("irc-65535")];

 static void ip_conntrack_irc_fini(void);

 static int __init ip_conntrack_irc_init(void)
 {
 	int i, ret;
 	struct ip_conntrack_helper *hlpr;
 	char *tmpname;

 	if (max_dcc_channels < 1) {
 		printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
 		return -EBUSY;
 	}

 	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++) {
 		hlpr = &irc_helpers[i];
 		hlpr->tuple.src.u.tcp.port = htons(ports[i]);
 		hlpr->tuple.dst.protonum = IPPROTO_TCP;
 		hlpr->mask.src.u.tcp.port = htons(0xFFFF);
 		hlpr->mask.dst.protonum = 0xFF;
 		hlpr->max_expected = max_dcc_channels;
 		hlpr->timeout = dcc_timeout;
 		hlpr->me = THIS_MODULE;
 		hlpr->help = help;

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

 		DEBUGP("port #%d: %d\n", i, ports[i]);

 		ret = ip_conntrack_helper_register(hlpr);

 		if (ret) {
 			printk("ip_conntrack_irc: ERROR registering port %d\n",
 				ports[i]);
 			ip_conntrack_irc_fini();
 			return -EBUSY;
 		}
 	}
 	return 0;
 }

 /* This function is intentionally _NOT_ defined as __exit, because
  * it is needed by the init function */
 static void ip_conntrack_irc_fini(void)
 {
 	int i;
 	for (i = 0; i < ports_c; i++) {
 		DEBUGP("unregistering port %d\n",
 		       ports[i]);
 		ip_conntrack_helper_unregister(&irc_helpers[i]);
 	}
 	kfree(irc_buffer);
 }

 module_init(ip_conntrack_irc_init);
 module_exit(ip_conntrack_irc_fini);
	/* 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
	*
	* ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp
	*
	* 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.
	**
	* Module load syntax:
	* insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS>
	* max_dcc_channels=n dcc_timeout=secs
	*
	* please give the ports of all IRC servers You wish to connect to.
	* If You don't specify ports, the default will be port 6667.
	* With max_dcc_channels you can define the maximum number of not
	* yet answered DCC channels per IRC session (default 8).
	* With dcc_timeout you can specify how long the system waits for
	* an expected DCC channel (default 300 seconds).
	*
	*/

	#include <linux/module.h>
	#include <linux/netfilter.h>
	#include <linux/ip.h>
	#include <net/checksum.h>
	#include <net/tcp.h>

	#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
	#include <linux/netfilter_ipv4/ip_conntrack_irc.h>
	#include <linux/moduleparam.h>

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

	unsigned int (ip_nat_irc_hook)(struct sk_buff *pskb,
	enum ip_conntrack_info ctinfo,
	unsigned int matchoff,
	unsigned int matchlen,
	struct ip_conntrack_expect *exp);
	EXPORT_SYMBOL_GPL(ip_nat_irc_hook);

	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
	MODULE_LICENSE("GPL");
	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 *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
	#define MINMATCHLEN 5

	#if 0
	#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \
	__FILE__, __FUNCTION__ , ## args)
	#else
	#define DEBUGP(format, args...)
	#endif

	static int parse_dcc(char data, char data_end, u_int32_t *ip,
	u_int16_t port, char ad_beg_p, char *ad_end_p)
	/* 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 */
	{

	/* at least 12: "AAAAAAAA P\1\n" */
	while (*data++ != ' ')
	if (data > data_end - 12)
	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 **pskb,
	struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
	{
	unsigned int dataoff;
	struct tcphdr _tcph, *th;
	char data, data_limit, *ib_ptr;
	int dir = CTINFO2DIR(ctinfo);
	struct ip_conntrack_expect *exp;
	u32 seq;
	u_int32_t dcc_ip;
	u_int16_t dcc_port;
	int i, ret = NF_ACCEPT;
	char addr_beg_p, addr_end_p;

	DEBUGP("entered\n");

	/* 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) {
	DEBUGP("Conntrackinfo = %u\n", ctinfo);
	return NF_ACCEPT;
	}

	/* Not a full tcp header? */
	th = skb_header_pointer(pskb, (pskb)->nh.iph->ihl*4,
	sizeof(_tcph), &_tcph);
	if (th == NULL)
	return NF_ACCEPT;

	/* No data? */
	dataoff = (pskb)->nh.iph->ihl4 + th->doff*4;
	if (dataoff >= (*pskb)->len)
	return NF_ACCEPT;

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

	data = ib_ptr;
	data_limit = ib_ptr + (*pskb)->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 */

	DEBUGP("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;
	}

	DEBUGP("DCC %s detected\n", dccprotos[i]);
	data += strlen(dccprotos[i]);
	/* we have at least
	* (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
	* data left (== 14/13 bytes) */
	if (parse_dcc((char *)data, data_limit, &dcc_ip,
	&dcc_port, &addr_beg_p, &addr_end_p)) {
	/* unable to parse */
	DEBUGP("unable to parse dcc command\n");
	continue;
	}
	DEBUGP("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
	* Tiago Sousa <mirage@kaotik.org> */
	if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
	&& ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.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(ct->tuplehash[dir].tuple.src.ip),
	HIPQUAD(dcc_ip), dcc_port);

	continue;
	}

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

	/* save position of address in dcc string,
	* necessary for NAT */
	DEBUGP("tcph->seq = %u\n", th->seq);
	seq = ntohl(th->seq) + (addr_beg_p - ib_ptr);

	/* We refer to the reverse direction ("!dir")
	* tuples here, because we're expecting
	* something in the other * direction.
	* Doesn't matter unless NAT is happening. */
	exp->tuple = ((struct ip_conntrack_tuple)
	{ { 0, { 0 } },
	{ ct->tuplehash[!dir].tuple.dst.ip,
	{ .tcp = { htons(dcc_port) } },
	IPPROTO_TCP }});
	exp->mask = ((struct ip_conntrack_tuple)
	{ { 0, { 0 } },
	{ htonl(0xFFFFFFFF),
	{ .tcp = { htons(0xFFFF) } }, 0xFF }});
	exp->expectfn = NULL;
	exp->flags = 0;
	if (ip_nat_irc_hook)
	ret = ip_nat_irc_hook(pskb, ctinfo,
	addr_beg_p - ib_ptr,
	addr_end_p - addr_beg_p,
	exp);
	else if (ip_conntrack_expect_related(exp) != 0)
	ret = NF_DROP;
	ip_conntrack_expect_put(exp);
	goto out;
	} /* for .. NUM_DCCPROTO */
	} /* while data < ... */

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

	static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
	static char irc_names[MAX_PORTS][sizeof("irc-65535")];

	static void ip_conntrack_irc_fini(void);

	static int __init ip_conntrack_irc_init(void)
	{
	int i, ret;
	struct ip_conntrack_helper *hlpr;
	char *tmpname;

	if (max_dcc_channels < 1) {
	printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
	return -EBUSY;
	}

	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++) {
	hlpr = &irc_helpers[i];
	hlpr->tuple.src.u.tcp.port = htons(ports[i]);
	hlpr->tuple.dst.protonum = IPPROTO_TCP;
	hlpr->mask.src.u.tcp.port = htons(0xFFFF);
	hlpr->mask.dst.protonum = 0xFF;
	hlpr->max_expected = max_dcc_channels;
	hlpr->timeout = dcc_timeout;
	hlpr->me = THIS_MODULE;
	hlpr->help = help;

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

	DEBUGP("port #%d: %d\n", i, ports[i]);

	ret = ip_conntrack_helper_register(hlpr);

	if (ret) {
	printk("ip_conntrack_irc: ERROR registering port %d\n",
	ports[i]);
	ip_conntrack_irc_fini();
	return -EBUSY;
	}
	}
	return 0;
	}

	/* This function is intentionally _NOT_ defined as __exit, because
	* it is needed by the init function */
	static void ip_conntrack_irc_fini(void)
	{
	int i;
	for (i = 0; i < ports_c; i++) {
	DEBUGP("unregistering port %d\n",
	ports[i]);
	ip_conntrack_helper_unregister(&irc_helpers[i]);
	}
	kfree(irc_buffer);
	}

	module_init(ip_conntrack_irc_init);
	module_exit(ip_conntrack_irc_fini);