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netfilter: xtables: inclusion of xt_TEE 

xt_TEE can be used to clone and reroute a packet. This can for
example be used to copy traffic at a router for logging purposes
to another dedicated machine.

References: http://www.gossamer-threads.com/lists/iptables/devel/68781
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
hifive-unleashed-5.1
Jan Engelhardt 2010-04-19 14:17:47 +02:00 committed by Patrick McHardy
parent f0d57a54aa
commit e281b19897
7 changed files with 276 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/netfilter/Kbuild
View File

@ -16,6 +16,7 @@ header-y += xt_RATEEST.h
header-y += xt_SECMARK.h
header-y += xt_TCPMSS.h
header-y += xt_TCPOPTSTRIP.h
header-y += xt_TEE.h
header-y += xt_TPROXY.h
header-y += xt_comment.h
header-y += xt_connbytes.h

9
include/linux/netfilter/xt_TEE.h 100644
View File

@ -0,0 +1,9 @@
#ifndef _XT_TEE_TARGET_H
#define _XT_TEE_TARGET_H
struct xt_tee_tginfo {
union nf_inet_addr gw;
char oif[16];
};
#endif /* _XT_TEE_TARGET_H */

1
net/ipv4/ip_output.c
View File

@ -309,6 +309,7 @@ int ip_output(struct sk_buff *skb)
ip_finish_output,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
EXPORT_SYMBOL_GPL(ip_output);
int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
{

1
net/ipv6/ip6_output.c
View File

@ -176,6 +176,7 @@ int ip6_output(struct sk_buff *skb)
ip6_finish_output,
!(IP6CB(skb)->flags & IP6SKB_REROUTED));
}
EXPORT_SYMBOL_GPL(ip6_output);
/*
* xmit an sk_buff (used by TCP)

7
net/netfilter/Kconfig
View File

@ -502,6 +502,13 @@ config NETFILTER_XT_TARGET_RATEEST
To compile it as a module, choose M here. If unsure, say N.
config NETFILTER_XT_TARGET_TEE
tristate '"TEE" - packet cloning to alternate destiantion'
depends on NETFILTER_ADVANCED
---help---
This option adds a "TEE" target with which a packet can be cloned and
this clone be rerouted to another nexthop.
config NETFILTER_XT_TARGET_TPROXY
tristate '"TPROXY" target support (EXPERIMENTAL)'
depends on EXPERIMENTAL

1
net/netfilter/Makefile
View File

@ -59,6 +59,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TPROXY) += xt_TPROXY.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPOPTSTRIP) += xt_TCPOPTSTRIP.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TEE) += xt_TEE.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o
# matches

256
net/netfilter/xt_TEE.c 100644
View File

@ -0,0 +1,256 @@
/*
* "TEE" target extension for Xtables
* Copyright © Sebastian Claßen, 2007
* Jan Engelhardt, 2007-2010
*
* based on ipt_ROUTE.c from Cédric de Launois
* <delaunois@info.ucl.be>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 or later, as published by the Free Software Foundation.
*/
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/route.h>
#include <linux/skbuff.h>
#include <net/checksum.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/route.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_TEE.h>
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
# define WITH_CONNTRACK 1
# include <net/netfilter/nf_conntrack.h>
#endif
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
# define WITH_IPV6 1
#endif
static const union nf_inet_addr tee_zero_address;
static struct net *pick_net(struct sk_buff *skb)
{
#ifdef CONFIG_NET_NS
const struct dst_entry *dst;
if (skb->dev != NULL)
return dev_net(skb->dev);
dst = skb_dst(skb);
if (dst != NULL && dst->dev != NULL)
return dev_net(dst->dev);
#endif
return &init_net;
}
static bool tee_tg_route_oif(struct flowi *f, struct net *net,
const struct xt_tee_tginfo *info)
{
const struct net_device *dev;
if (*info->oif != '\0')
return true;
dev = dev_get_by_name(net, info->oif);
if (dev == NULL)
return false;
f->oif = dev->ifindex;
return true;
}
static bool
tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
{
const struct iphdr *iph = ip_hdr(skb);
struct net *net = pick_net(skb);
struct rtable *rt;
struct flowi fl;
memset(&fl, 0, sizeof(fl));
if (!tee_tg_route_oif(&fl, net, info))
return false;
fl.nl_u.ip4_u.daddr = info->gw.ip;
fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
if (ip_route_output_key(net, &rt, &fl) != 0)
return false;
dst_release(skb_dst(skb));
skb_dst_set(skb, &rt->u.dst);
skb->dev = rt->u.dst.dev;
skb->protocol = htons(ETH_P_IP);
return true;
}
static unsigned int
tee_tg4(struct sk_buff *skb, const struct xt_target_param *par)
{
const struct xt_tee_tginfo *info = par->targinfo;
struct iphdr *iph;
/*
* Copy the skb, and route the copy. Will later return %XT_CONTINUE for
* the original skb, which should continue on its way as if nothing has
* happened. The copy should be independently delivered to the TEE
* --gateway.
*/
skb = pskb_copy(skb, GFP_ATOMIC);
if (skb == NULL)
return XT_CONTINUE;
#ifdef WITH_CONNTRACK
/* Avoid counting cloned packets towards the original connection. */
nf_conntrack_put(skb->nfct);
skb->nfct = &nf_conntrack_untracked.ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);
#endif
/*
* If we are in PREROUTING/INPUT, the checksum must be recalculated
* since the length could have changed as a result of defragmentation.
*
* We also decrease the TTL to mitigate potential TEE loops
* between two hosts.
*
* Set %IP_DF so that the original source is notified of a potentially
* decreased MTU on the clone route. IPv6 does this too.
*/
iph = ip_hdr(skb);
iph->frag_off |= htons(IP_DF);
if (par->hooknum == NF_INET_PRE_ROUTING ||
par->hooknum == NF_INET_LOCAL_IN)
--iph->ttl;
ip_send_check(iph);
/*
* Xtables is not reentrant currently, so a choice has to be made:
* 1. return absolute verdict for the original and let the cloned
* packet travel through the chains
* 2. let the original continue travelling and not pass the clone
* to Xtables.
* #2 is chosen. Normally, we would use ip_local_out for the clone.
* Because iph->check is already correct and we don't pass it to
* Xtables anyway, a shortcut to dst_output [forwards to ip_output] can
* be taken. %IPSKB_REROUTED needs to be set so that ip_output does not
* invoke POSTROUTING on the cloned packet.
*/
IPCB(skb)->flags |= IPSKB_REROUTED;
if (tee_tg_route4(skb, info))
ip_output(skb);
else
kfree_skb(skb);
return XT_CONTINUE;
}
#ifdef WITH_IPV6
static bool
tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
{
const struct ipv6hdr *iph = ipv6_hdr(skb);
struct net *net = pick_net(skb);
struct dst_entry *dst;
struct flowi fl;
memset(&fl, 0, sizeof(fl));
if (!tee_tg_route_oif(&fl, net, info))
return false;
fl.nl_u.ip6_u.daddr = info->gw.in6;
fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
(iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
dst = ip6_route_output(net, NULL, &fl);
if (dst == NULL)
return false;
dst_release(skb_dst(skb));
skb_dst_set(skb, dst);
skb->dev = dst->dev;
skb->protocol = htons(ETH_P_IPV6);
return true;
}
static unsigned int
tee_tg6(struct sk_buff *skb, const struct xt_target_param *par)
{
const struct xt_tee_tginfo *info = par->targinfo;
skb = pskb_copy(skb, GFP_ATOMIC);
if (skb == NULL)
return XT_CONTINUE;
#ifdef WITH_CONNTRACK
nf_conntrack_put(skb->nfct);
skb->nfct = &nf_conntrack_untracked.ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);
#endif
if (par->hooknum == NF_INET_PRE_ROUTING ||
par->hooknum == NF_INET_LOCAL_IN) {
struct ipv6hdr *iph = ipv6_hdr(skb);
--iph->hop_limit;
}
IP6CB(skb)->flags |= IP6SKB_REROUTED;
if (tee_tg_route6(skb, info))
ip6_output(skb);
else
kfree_skb(skb);
return XT_CONTINUE;
}
#endif /* WITH_IPV6 */
static int tee_tg_check(const struct xt_tgchk_param *par)
{
const struct xt_tee_tginfo *info = par->targinfo;
if (info->oif[sizeof(info->oif)-1] != '\0')
return -EINVAL;
/* 0.0.0.0 and :: not allowed */
return (memcmp(&info->gw, &tee_zero_address,
sizeof(tee_zero_address)) == 0) ? -EINVAL : 0;
}
static struct xt_target tee_tg_reg[] __read_mostly = {
{
.name = "TEE",
.revision = 1,
.family = NFPROTO_IPV4,
.target = tee_tg4,
.targetsize = sizeof(struct xt_tee_tginfo),
.checkentry = tee_tg_check,
.me = THIS_MODULE,
},
#ifdef WITH_IPV6
{
.name = "TEE",
.revision = 1,
.family = NFPROTO_IPV6,
.target = tee_tg6,
.targetsize = sizeof(struct xt_tee_tginfo),
.checkentry = tee_tg_check,
.me = THIS_MODULE,
},
#endif
};
static int __init tee_tg_init(void)
{
return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
}
static void __exit tee_tg_exit(void)
{
xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
}
module_init(tee_tg_init);
module_exit(tee_tg_exit);
MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: Reroute packet copy");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_TEE");
MODULE_ALIAS("ip6t_TEE");