Commit 45ca4e0c authored by Máté Eckl's avatar Máté Eckl Committed by Pablo Neira Ayuso
Browse files

netfilter: Libify xt_TPROXY



The extracted functions will likely be usefull to implement tproxy
support in nf_tables.

Extrancted functions:
	- nf_tproxy_sk_is_transparent
	- nf_tproxy_laddr4
	- nf_tproxy_handle_time_wait4
	- nf_tproxy_get_sock_v4
	- nf_tproxy_laddr6
	- nf_tproxy_handle_time_wait6
	- nf_tproxy_get_sock_v6

(nf_)tproxy_handle_time_wait6 also needed some refactor as its current
implementation was xtables-specific.

Signed-off-by: default avatarMáté Eckl <ecklm94@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 8d6e5557
#ifndef _NF_TPROXY_H_
#define _NF_TPROXY_H_
#include <net/tcp.h>
enum nf_tproxy_lookup_t {
NF_TPROXY_LOOKUP_LISTENER,
NF_TPROXY_LOOKUP_ESTABLISHED,
};
static inline bool nf_tproxy_sk_is_transparent(struct sock *sk)
{
if (inet_sk_transparent(sk))
return true;
sock_gen_put(sk);
return false;
}
__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr);
/**
* nf_tproxy_handle_time_wait4 - handle IPv4 TCP TIME_WAIT reopen redirections
* @skb: The skb being processed.
* @laddr: IPv4 address to redirect to or zero.
* @lport: TCP port to redirect to or zero.
* @sk: The TIME_WAIT TCP socket found by the lookup.
*
* We have to handle SYN packets arriving to TIME_WAIT sockets
* differently: instead of reopening the connection we should rather
* redirect the new connection to the proxy if there's a listener
* socket present.
*
* nf_tproxy_handle_time_wait4() consumes the socket reference passed in.
*
* Returns the listener socket if there's one, the TIME_WAIT socket if
* no such listener is found, or NULL if the TCP header is incomplete.
*/
struct sock *
nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
__be32 laddr, __be16 lport, struct sock *sk);
/*
* This is used when the user wants to intercept a connection matching
* an explicit iptables rule. In this case the sockets are assumed
* matching in preference order:
*
* - match: if there's a fully established connection matching the
* _packet_ tuple, it is returned, assuming the redirection
* already took place and we process a packet belonging to an
* established connection
*
* - match: if there's a listening socket matching the redirection
* (e.g. on-port & on-ip of the connection), it is returned,
* regardless if it was bound to 0.0.0.0 or an explicit
* address. The reasoning is that if there's an explicit rule, it
* does not really matter if the listener is bound to an interface
* or to 0. The user already stated that he wants redirection
* (since he added the rule).
*
* Please note that there's an overlap between what a TPROXY target
* and a socket match will match. Normally if you have both rules the
* "socket" match will be the first one, effectively all packets
* belonging to established connections going through that one.
*/
struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type);
const struct in6_addr *
nf_tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
const struct in6_addr *daddr);
/**
* nf_tproxy_handle_time_wait6 - handle IPv6 TCP TIME_WAIT reopen redirections
* @skb: The skb being processed.
* @tproto: Transport protocol.
* @thoff: Transport protocol header offset.
* @net: Network namespace.
* @laddr: IPv6 address to redirect to.
* @lport: TCP port to redirect to or zero.
* @sk: The TIME_WAIT TCP socket found by the lookup.
*
* We have to handle SYN packets arriving to TIME_WAIT sockets
* differently: instead of reopening the connection we should rather
* redirect the new connection to the proxy if there's a listener
* socket present.
*
* nf_tproxy_handle_time_wait6() consumes the socket reference passed in.
*
* Returns the listener socket if there's one, the TIME_WAIT socket if
* no such listener is found, or NULL if the TCP header is incomplete.
*/
struct sock *
nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
struct net *net,
const struct in6_addr *laddr,
const __be16 lport,
struct sock *sk);
struct sock *
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type);
#endif /* _NF_TPROXY_H_ */
......@@ -29,7 +29,10 @@ config NF_SOCKET_IPV4
tristate "IPv4 socket lookup support"
help
This option enables the IPv4 socket lookup infrastructure. This is
is required by the iptables socket match.
is required by the {ip,nf}tables socket match.
config NF_TPROXY_IPV4
tristate "IPv4 tproxy support"
if NF_TABLES
......
......@@ -17,6 +17,7 @@ obj-$(CONFIG_NF_NAT_IPV4) += nf_nat_ipv4.o
obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o
obj-$(CONFIG_NF_SOCKET_IPV4) += nf_socket_ipv4.o
obj-$(CONFIG_NF_TPROXY_IPV4) += nf_tproxy_ipv4.o
# logging
obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o
......
/*
* Copyright (C) 2007-2008 BalaBit IT Ltd.
* Author: Krisztian Kovacs
*
* 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 <net/netfilter/nf_tproxy.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/inet_sock.h>
#include <linux/ip.h>
#include <net/checksum.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <linux/inetdevice.h>
struct sock *
nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
__be32 laddr, __be16 lport, struct sock *sk)
{
const struct iphdr *iph = ip_hdr(skb);
struct tcphdr _hdr, *hp;
hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
if (hp == NULL) {
inet_twsk_put(inet_twsk(sk));
return NULL;
}
if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
/* SYN to a TIME_WAIT socket, we'd rather redirect it
* to a listener socket if there's one */
struct sock *sk2;
sk2 = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
iph->saddr, laddr ? laddr : iph->daddr,
hp->source, lport ? lport : hp->dest,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
if (sk2) {
inet_twsk_deschedule_put(inet_twsk(sk));
sk = sk2;
}
}
return sk;
}
EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4);
__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
{
struct in_device *indev;
__be32 laddr;
if (user_laddr)
return user_laddr;
laddr = 0;
indev = __in_dev_get_rcu(skb->dev);
for_primary_ifa(indev) {
laddr = ifa->ifa_local;
break;
} endfor_ifa(indev);
return laddr ? laddr : daddr;
}
EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);
struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
tcph = hp;
sk = inet_lookup_listener(net, &tcp_hashinfo, skb,
ip_hdrlen(skb) +
__tcp_hdrlen(tcph),
saddr, sport,
daddr, dport,
in->ifindex, 0);
if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
break;
case NF_TPROXY_LOOKUP_ESTABLISHED:
sk = inet_lookup_established(net, &tcp_hashinfo,
saddr, sport, daddr, dport,
in->ifindex);
break;
default:
BUG();
}
break;
case IPPROTO_UDP:
sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
if (sk) {
int connected = (sk->sk_state == TCP_ESTABLISHED);
int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED &&
(!connected || wildcard)) ||
(lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) {
sock_put(sk);
sk = NULL;
}
}
break;
default:
WARN_ON(1);
sk = NULL;
}
pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
return sk;
}
EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support");
......@@ -29,7 +29,10 @@ config NF_SOCKET_IPV6
tristate "IPv6 socket lookup support"
help
This option enables the IPv6 socket lookup infrastructure. This
is used by the ip6tables socket match.
is used by the {ip6,nf}tables socket match.
config NF_TPROXY_IPV6
tristate "IPv6 tproxy support"
if NF_TABLES
......
......@@ -26,6 +26,7 @@ nf_defrag_ipv6-y := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o
obj-$(CONFIG_NF_SOCKET_IPV6) += nf_socket_ipv6.o
obj-$(CONFIG_NF_TPROXY_IPV6) += nf_tproxy_ipv6.o
# logging
obj-$(CONFIG_NF_LOG_IPV6) += nf_log_ipv6.o
......
#include <net/netfilter/nf_tproxy.h>
#include <linux/module.h>
#include <net/inet6_hashtables.h>
#include <net/addrconf.h>
#include <net/udp.h>
#include <net/tcp.h>
const struct in6_addr *
nf_tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
const struct in6_addr *daddr)
{
struct inet6_dev *indev;
struct inet6_ifaddr *ifa;
struct in6_addr *laddr;
if (!ipv6_addr_any(user_laddr))
return user_laddr;
laddr = NULL;
indev = __in6_dev_get(skb->dev);
if (indev) {
read_lock_bh(&indev->lock);
list_for_each_entry(ifa, &indev->addr_list, if_list) {
if (ifa->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED))
continue;
laddr = &ifa->addr;
break;
}
read_unlock_bh(&indev->lock);
}
return laddr ? laddr : daddr;
}
EXPORT_SYMBOL_GPL(nf_tproxy_laddr6);
struct sock *
nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
struct net *net,
const struct in6_addr *laddr,
const __be16 lport,
struct sock *sk)
{
const struct ipv6hdr *iph = ipv6_hdr(skb);
struct tcphdr _hdr, *hp;
hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
if (hp == NULL) {
inet_twsk_put(inet_twsk(sk));
return NULL;
}
if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
/* SYN to a TIME_WAIT socket, we'd rather redirect it
* to a listener socket if there's one */
struct sock *sk2;
sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, hp, tproto,
&iph->saddr,
nf_tproxy_laddr6(skb, laddr, &iph->daddr),
hp->source,
lport ? lport : hp->dest,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
if (sk2) {
inet_twsk_deschedule_put(inet_twsk(sk));
sk = sk2;
}
}
return sk;
}
EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait6);
struct sock *
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
tcph = hp;
sk = inet6_lookup_listener(net, &tcp_hashinfo, skb,
thoff + __tcp_hdrlen(tcph),
saddr, sport,
daddr, ntohs(dport),
in->ifindex, 0);
if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
break;
case NF_TPROXY_LOOKUP_ESTABLISHED:
sk = __inet6_lookup_established(net, &tcp_hashinfo,
saddr, sport, daddr, ntohs(dport),
in->ifindex, 0);
break;
default:
BUG();
}
break;
case IPPROTO_UDP:
sk = udp6_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
if (sk) {
int connected = (sk->sk_state == TCP_ESTABLISHED);
int wildcard = ipv6_addr_any(&sk->sk_v6_rcv_saddr);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
(lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) {
sock_put(sk);
sk = NULL;
}
}
break;
default:
WARN_ON(1);
sk = NULL;
}
pr_debug("tproxy socket lookup: proto %u %pI6:%u -> %pI6:%u, lookup type: %d, sock %p\n",
protocol, saddr, ntohs(sport), daddr, ntohs(dport), lookup_type, sk);
return sk;
}
EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v6);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support");
......@@ -989,6 +989,8 @@ config NETFILTER_XT_TARGET_TPROXY
depends on IP_NF_MANGLE
select NF_DEFRAG_IPV4
select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES != n
select NF_TPROXY_IPV4
select NF_TPROXY_IPV6 if IP6_NF_IPTABLES
help
This option adds a `TPROXY' target, which is somewhat similar to
REDIRECT. It can only be used in the mangle table and is useful
......
......@@ -33,253 +33,9 @@
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#endif
#include <net/netfilter/nf_tproxy.h>
#include <linux/netfilter/xt_TPROXY.h>
enum nf_tproxy_lookup_t {
NFT_LOOKUP_LISTENER,
NFT_LOOKUP_ESTABLISHED,
};
static bool tproxy_sk_is_transparent(struct sock *sk)
{
if (inet_sk_transparent(sk))
return true;
sock_gen_put(sk);
return false;
}
static inline __be32
tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
{
struct in_device *indev;
__be32 laddr;
if (user_laddr)
return user_laddr;
laddr = 0;
indev = __in_dev_get_rcu(skb->dev);
for_primary_ifa(indev) {
laddr = ifa->ifa_local;
break;
} endfor_ifa(indev);
return laddr ? laddr : daddr;
}
/*
* This is used when the user wants to intercept a connection matching
* an explicit iptables rule. In this case the sockets are assumed
* matching in preference order:
*
* - match: if there's a fully established connection matching the
* _packet_ tuple, it is returned, assuming the redirection
* already took place and we process a packet belonging to an
* established connection
*
* - match: if there's a listening socket matching the redirection
* (e.g. on-port & on-ip of the connection), it is returned,
* regardless if it was bound to 0.0.0.0 or an explicit
* address. The reasoning is that if there's an explicit rule, it
* does not really matter if the listener is bound to an interface
* or to 0. The user already stated that he wants redirection
* (since he added the rule).
*
* Please note that there's an overlap between what a TPROXY target
* and a socket match will match. Normally if you have both rules the
* "socket" match will be the first one, effectively all packets
* belonging to established connections going through that one.
*/
static inline struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NFT_LOOKUP_LISTENER:
tcph = hp;
sk = inet_lookup_listener(net, &tcp_hashinfo, skb,
ip_hdrlen(skb) +
__tcp_hdrlen(tcph),
saddr, sport,
daddr, dport,
in->ifindex, 0);
if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
break;
case NFT_LOOKUP_ESTABLISHED:
sk = inet_lookup_established(net, &tcp_hashinfo,
saddr, sport, daddr, dport,
in->ifindex);
break;
default:
BUG();
}
break;
case IPPROTO_UDP:
sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
if (sk) {
int connected = (sk->sk_state == TCP_ESTABLISHED);
int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too
*/
if ((lookup_type == NFT_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
(lookup_type == NFT_LOOKUP_LISTENER && connected)) {
sock_put(sk);
sk = NULL;
}
}
break;
default:
WARN_ON(1);
sk = NULL;
}
pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
return sk;
}
#ifdef XT_TPROXY_HAVE_IPV6
static inline struct sock *
nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
struct tcphdr *tcph;
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NFT_LOOKUP_LISTENER:
tcph = hp;
sk = inet6_lookup_listener(net, &tcp_hashinfo, skb,
thoff + __tcp_hdrlen(tcph),