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authorMáté Eckl <ecklm94@gmail.com>2018-06-01 20:44:56 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2018-06-03 00:02:05 +0200
commit45ca4e0cf2734f8cc14b43e47c23618215abf1b8 (patch)
tree5772c57c59d7d30743a4175ff6dc15c1d2234526 /net/ipv4
parent8d6e555773690e6fdefd99723fcd0a7e432c0c90 (diff)
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: Máté Eckl <ecklm94@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/Kconfig5
-rw-r--r--net/ipv4/netfilter/Makefile1
-rw-r--r--net/ipv4/netfilter/nf_tproxy_ipv4.c147
3 files changed, 152 insertions, 1 deletions
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index d03bc5a01a70..bbfc356cb1b5 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -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
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index c4b05b174091..8394c17c269f 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -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
diff --git a/net/ipv4/netfilter/nf_tproxy_ipv4.c b/net/ipv4/netfilter/nf_tproxy_ipv4.c
new file mode 100644
index 000000000000..805e83ec3ad9
--- /dev/null
+++ b/net/ipv4/netfilter/nf_tproxy_ipv4.c
@@ -0,0 +1,147 @@
+/*
+ * 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");