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netfilter: refactor NAT redirect IPv4 to use it from nf_tables

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This patch refactors the IPv4 code so it can be usable both from xt and
nf_tables.

A similar patch follows-up to handle IPv6.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Arturo Borrero 2014-10-16 12:23:29 +02:00 • committed by Pablo Neira Ayuso
commit 8b13eddfdf
6 changed files with 101 additions and 42 deletions
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9
include/net/netfilter/ipv4/nf_nat_redirect.h Normal file
View file

@ -0,0 +1,9 @@
#ifndef _NF_NAT_REDIRECT_IPV4_H_
#define _NF_NAT_REDIRECT_IPV4_H_
unsigned int
nf_nat_redirect_ipv4(struct sk_buff *skb,
const struct nf_nat_ipv4_multi_range_compat *mr,
unsigned int hooknum);
#endif /* _NF_NAT_REDIRECT_IPV4_H_ */

6
net/ipv4/netfilter/Kconfig
View file

@ -104,6 +104,12 @@ config NF_NAT_MASQUERADE_IPV4
This is the kernel functionality to provide NAT in the masquerade
flavour (automatic source address selection).
config NF_NAT_REDIRECT_IPV4
tristate "IPv4 redirect support"
help
This is the kernel functionality to provide NAT in the redirect
flavour (redirect packets to local machine).
config NFT_MASQ_IPV4
tristate "IPv4 masquerading support for nf_tables"
depends on NF_TABLES_IPV4

1
net/ipv4/netfilter/Makefile
View file

@ -31,6 +31,7 @@ obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
obj-$(CONFIG_NF_NAT_MASQUERADE_IPV4) += nf_nat_masquerade_ipv4.o
obj-$(CONFIG_NF_NAT_REDIRECT_IPV4) += nf_nat_redirect_ipv4.o
# NAT protocols (nf_nat)
obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o

82
net/ipv4/netfilter/nf_nat_redirect_ipv4.c Normal file
View file

@ -0,0 +1,82 @@
/*
* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* 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.
*
* Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
* NAT funded by Astaro.
*/
#include <linux/if.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/types.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/x_tables.h>
#include <net/addrconf.h>
#include <net/checksum.h>
#include <net/protocol.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/ipv4/nf_nat_redirect.h>
unsigned int
nf_nat_redirect_ipv4(struct sk_buff *skb,
const struct nf_nat_ipv4_multi_range_compat *mr,
unsigned int hooknum)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
__be32 newdst;
struct nf_nat_range newrange;
NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING ||
hooknum == NF_INET_LOCAL_OUT);
ct = nf_ct_get(skb, &ctinfo);
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
/* Local packets: make them go to loopback */
if (hooknum == NF_INET_LOCAL_OUT) {
newdst = htonl(0x7F000001);
} else {
struct in_device *indev;
struct in_ifaddr *ifa;
newdst = 0;
rcu_read_lock();
indev = __in_dev_get_rcu(skb->dev);
if (indev != NULL) {
ifa = indev->ifa_list;
newdst = ifa->ifa_local;
}
rcu_read_unlock();
if (!newdst)
return NF_DROP;
}
/* Transfer from original range. */
memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.ip = newdst;
newrange.max_addr.ip = newdst;
newrange.min_proto = mr->range[0].min;
newrange.max_proto = mr->range[0].max;
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
}
EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");

1
net/netfilter/Kconfig
View file

@ -835,6 +835,7 @@ config NETFILTER_XT_TARGET_RATEEST
config NETFILTER_XT_TARGET_REDIRECT
tristate "REDIRECT target support"
depends on NF_NAT
select NF_NAT_REDIRECT_IPV4
---help---
REDIRECT is a special case of NAT: all incoming connections are
mapped onto the incoming interface's address, causing the packets to

44
net/netfilter/xt_REDIRECT.c
View file

@ -26,6 +26,7 @@
#include <net/checksum.h>
#include <net/protocol.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/ipv4/nf_nat_redirect.h>
static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
@ -98,48 +99,7 @@ static int redirect_tg4_check(const struct xt_tgchk_param *par)
static unsigned int
redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
__be32 newdst;
const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
struct nf_nat_range newrange;
NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
par->hooknum == NF_INET_LOCAL_OUT);
ct = nf_ct_get(skb, &ctinfo);
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
/* Local packets: make them go to loopback */
if (par->hooknum == NF_INET_LOCAL_OUT)
newdst = htonl(0x7F000001);
else {
struct in_device *indev;
struct in_ifaddr *ifa;
newdst = 0;
rcu_read_lock();
indev = __in_dev_get_rcu(skb->dev);
if (indev && (ifa = indev->ifa_list))
newdst = ifa->ifa_local;
rcu_read_unlock();
if (!newdst)
return NF_DROP;
}
/* Transfer from original range. */
memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.ip = newdst;
newrange.max_addr.ip = newdst;
newrange.min_proto = mr->range[0].min;
newrange.max_proto = mr->range[0].max;
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
return nf_nat_redirect_ipv4(skb, par->targinfo, par->hooknum);
}
static struct xt_target redirect_tg_reg[] __read_mostly = {