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DEFINITIONS
This source file includes following definitions.
- parse_dcc
- help
- nf_conntrack_irc_init
- 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_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);