net/netfilter/nf_conntrack_irc.c - kernel/prism - 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
  *
  * 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);
	/* 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);