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/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/in.h>
#include <linux/udp.h>
#include <linux/netfilter.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_tftp.h>
MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
MODULE_DESCRIPTION("TFTP connection tracking helper");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_conntrack_tftp");
#define MAX_PORTS 8
static unsigned short ports[MAX_PORTS];
static int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);
MODULE_PARM_DESC(ports, "Port numbers of TFTP servers");
unsigned int (*nf_nat_tftp_hook)(struct sk_buff **pskb,
enum ip_conntrack_info ctinfo,
struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_tftp_hook);
static int tftp_help(struct sk_buff **pskb,
unsigned int protoff,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct tftphdr _tftph, *tfh;
struct nf_conntrack_expect *exp;
struct nf_conntrack_tuple *tuple;
unsigned int ret = NF_ACCEPT;
int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
typeof(nf_nat_tftp_hook) nf_nat_tftp;
tfh = skb_header_pointer(*pskb, protoff + sizeof(struct udphdr),
sizeof(_tftph), &_tftph);
if (tfh == NULL)
return NF_ACCEPT;
switch (ntohs(tfh->opcode)) {
case TFTP_OPCODE_READ:
case TFTP_OPCODE_WRITE:
/* RRQ and WRQ works the same way */
NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
exp = nf_ct_expect_alloc(ct);
if (exp == NULL)
return NF_DROP;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
nf_ct_expect_init(exp, family, &tuple->src.u3, &tuple->dst.u3,
IPPROTO_UDP, NULL, &tuple->dst.u.udp.port);
pr_debug("expect: ");
NF_CT_DUMP_TUPLE(&exp->tuple);
nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
ret = nf_nat_tftp(pskb, ctinfo, exp);
else if (nf_ct_expect_related(exp) != 0)
ret = NF_DROP;
nf_ct_expect_put(exp);
break;
case TFTP_OPCODE_DATA:
case TFTP_OPCODE_ACK:
pr_debug("Data/ACK opcode\n");
break;
case TFTP_OPCODE_ERROR:
pr_debug("Error opcode\n");
break;
default:
pr_debug("Unknown opcode\n");
}
return ret;
}
static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly;
static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly;
static void nf_conntrack_tftp_fini(void)
{
int i, j;
for (i = 0; i < ports_c; i++) {
for (j = 0; j < 2; j++)
nf_conntrack_helper_unregister(&tftp[i][j]);
}
}
static int __init nf_conntrack_tftp_init(void)
{
int i, j, ret;
char *tmpname;
if (ports_c == 0)
ports[ports_c++] = TFTP_PORT;
for (i = 0; i < ports_c; i++) {
memset(&tftp[i], 0, sizeof(tftp[i]));
tftp[i][0].tuple.src.l3num = AF_INET;
tftp[i][1].tuple.src.l3num = AF_INET6;
for (j = 0; j < 2; j++) {
tftp[i][j].tuple.dst.protonum = IPPROTO_UDP;
tftp[i][j].tuple.src.u.udp.port = htons(ports[i]);
tftp[i][j].max_expected = 1;
tftp[i][j].timeout = 5 * 60; /* 5 minutes */
tftp[i][j].me = THIS_MODULE;
tftp[i][j].help = tftp_help;
tmpname = &tftp_names[i][j][0];
if (ports[i] == TFTP_PORT)
sprintf(tmpname, "tftp");
else
sprintf(tmpname, "tftp-%u", i);
tftp[i][j].name = tmpname;
ret = nf_conntrack_helper_register(&tftp[i][j]);
if (ret) {
printk("nf_ct_tftp: failed to register helper "
"for pf: %u port: %u\n",
tftp[i][j].tuple.src.l3num, ports[i]);
nf_conntrack_tftp_fini();
return ret;
}
}
}
return 0;
}
module_init(nf_conntrack_tftp_init);
module_exit(nf_conntrack_tftp_fini);
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