netfilter: tproxy: remove nf_tproxy_core, keep tw sk assigned to skb

The module was "permanent", due to the special tproxy skb->destructor.
Nowadays we have tcp early demux and its sock_edemux destructor in
networking core which can be used instead.

Thanks to early demux changes the input path now also handles
"skb->sk is tw socket" correctly, so this no longer needs the special
handling introduced with commit d503b30bd648b3cb4e5f50b65d27e389960cc6d9
(netfilter: tproxy: do not assign timewait sockets to skb->sk).

Thus:
- move assign_sock function to where its needed
- don't prevent timewait sockets from being assigned to the skb
- remove nf_tproxy_core.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 14 insertions, 82 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 56d22cae5906..c45fc1a60e0d 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -410,20 +410,6 @@ config NF_NAT_TFTP
 
 endif # NF_CONNTRACK
 
-# transparent proxy support
-config NETFILTER_TPROXY
-        tristate "Transparent proxying support"
-        depends on IP_NF_MANGLE
-        depends on NETFILTER_ADVANCED
-        help
-          This option enables transparent proxying support, that is,
-          support for handling non-locally bound IPv4 TCP and UDP sockets.
-          For it to work you will have to configure certain iptables rules
-          and use policy routing. For more information on how to set it up
-          see Documentation/networking/tproxy.txt.
-
-          To compile it as a module, choose M here.  If unsure, say N.
-
 config NETFILTER_XTABLES
         tristate "Netfilter Xtables support (required for ip_tables)"
         default m if NETFILTER_ADVANCED=n
@@ -720,10 +706,10 @@ config NETFILTER_XT_TARGET_TEE
         this clone be rerouted to another nexthop.
 
 config NETFILTER_XT_TARGET_TPROXY
-        tristate '"TPROXY" target support'
-        depends on NETFILTER_TPROXY
+        tristate '"TPROXY" target transparent proxying support'
         depends on NETFILTER_XTABLES
         depends on NETFILTER_ADVANCED
+        depends on IP_NF_MANGLE
         select NF_DEFRAG_IPV4
         select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES
         help
@@ -731,6 +717,9 @@ config NETFILTER_XT_TARGET_TPROXY
           REDIRECT.  It can only be used in the mangle table and is useful
           to redirect traffic to a transparent proxy.  It does _not_ depend
           on Netfilter connection tracking and NAT, unlike REDIRECT.
+          For it to work you will have to configure certain iptables rules
+          and use policy routing. For more information on how to set it up
+          see Documentation/networking/tproxy.txt.
 
           To compile it as a module, choose M here.  If unsure, say N.
 
@@ -1180,7 +1169,6 @@ config NETFILTER_XT_MATCH_SCTP
 
 config NETFILTER_XT_MATCH_SOCKET
         tristate '"socket" match support'
-        depends on NETFILTER_TPROXY
         depends on NETFILTER_XTABLES
         depends on NETFILTER_ADVANCED
         depends on !NF_CONNTRACK || NF_CONNTRACK
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index a1abf87d43bf..ebfa7dc747cd 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -61,9 +61,6 @@ obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
 obj-$(CONFIG_NF_NAT_SIP) += nf_nat_sip.o
 obj-$(CONFIG_NF_NAT_TFTP) += nf_nat_tftp.o
 
-# transparent proxy support
-obj-$(CONFIG_NETFILTER_TPROXY) += nf_tproxy_core.o
-
 # generic X tables 
 obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
 
diff --git a/net/netfilter/nf_tproxy_core.c b/net/netfilter/nf_tproxy_core.c
deleted file mode 100644
index 474d621cbc2e..000000000000
--- a/net/netfilter/nf_tproxy_core.c
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Transparent proxy support for Linux/iptables
- *
- * Copyright (c) 2006-2007 BalaBit IT Ltd.
- * Author: Balazs Scheidler, 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 <linux/module.h>
-
-#include <linux/net.h>
-#include <linux/if.h>
-#include <linux/netdevice.h>
-#include <net/udp.h>
-#include <net/netfilter/nf_tproxy_core.h>
-
-
-static void
-nf_tproxy_destructor(struct sk_buff *skb)
-{
-        struct sock *sk = skb->sk;
-
-        skb->sk = NULL;
-        skb->destructor = NULL;
-
-        if (sk)
-                sock_put(sk);
-}
-
-/* consumes sk */
-void
-nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
-{
-        /* assigning tw sockets complicates things; most
-         * skb->sk->X checks would have to test sk->sk_state first */
-        if (sk->sk_state == TCP_TIME_WAIT) {
-                inet_twsk_put(inet_twsk(sk));
-                return;
-        }
-
-        skb_orphan(skb);
-        skb->sk = sk;
-        skb->destructor = nf_tproxy_destructor;
-}
-EXPORT_SYMBOL_GPL(nf_tproxy_assign_sock);
-
-static int __init nf_tproxy_init(void)
-{
-        pr_info("NF_TPROXY: Transparent proxy support initialized, version 4.1.0\n");
-        pr_info("NF_TPROXY: Copyright (c) 2006-2007 BalaBit IT Ltd.\n");
-        return 0;
-}
-
-module_init(nf_tproxy_init);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Krisztian Kovacs");
-MODULE_DESCRIPTION("Transparent proxy support core routines");
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index d7f195388f66..17c40deafa4f 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -117,6 +117,15 @@ tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport,
         return sk;
 }
 
+/* assign a socket to the skb -- consumes sk */
+static void
+nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
+{
+        skb_orphan(skb);
+        skb->sk = sk;
+        skb->destructor = sock_edemux;
+}
+
 static unsigned int
 tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
            u_int32_t mark_mask, u_int32_t mark_value)