linux/net/netfilter/nf_nat_ftp.c

// SPDX-License-Identifier: GPL-2.0-only
/* FTP extension for TCP NAT alteration. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <[email protected]>
 */

#define pr_fmt(fmt) …

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/inet.h>
#include <linux/tcp.h>
#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_ftp.h>

#define NAT_HELPER_NAME …

MODULE_LICENSE(…) …;
MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_ALIAS_NF_NAT_HELPER(…);

/* FIXME: Time out? --RR */

static struct nf_conntrack_nat_helper nat_helper_ftp = …;

static int nf_nat_ftp_fmt_cmd(struct nf_conn *ct, enum nf_ct_ftp_type type,
			      char *buffer, size_t buflen,
			      union nf_inet_addr *addr, u16 port)
{ … }

/* So, this packet has hit the connection tracking matching code.
   Mangle it, and change the expectation to match the new version. */
static unsigned int nf_nat_ftp(struct sk_buff *skb,
			       enum ip_conntrack_info ctinfo,
			       enum nf_ct_ftp_type type,
			       unsigned int protoff,
			       unsigned int matchoff,
			       unsigned int matchlen,
			       struct nf_conntrack_expect *exp)
{ … }

static void __exit nf_nat_ftp_fini(void)
{ … }

static int __init nf_nat_ftp_init(void)
{ … }

/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
static int warn_set(const char *val, const struct kernel_param *kp)
{ … }
module_param_call(…);

module_init(…) …;
module_exit(nf_nat_ftp_fini);