Add iptables 'socket' match, which matches packets for which a TCP/UDP
socket lookup succeeds.
Signed-off-by: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
Signed-off-by: KOVACS Krisztian <hidden@xxxxxxxxxx>
---
net/netfilter/Kconfig | 12 +++++++
net/netfilter/Makefile | 1 +
net/netfilter/xt_socket.c | 83 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 96 insertions(+), 0 deletions(-)
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 2187cca..899fdde 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -632,6 +632,18 @@ config NETFILTER_XT_MATCH_SCTP
If you want to compile it as a module, say M here and read
<file:Documentation/kbuild/modules.txt>. If unsure, say `N'.
+config NETFILTER_XT_MATCH_SOCKET
+ tristate '"socket" match support'
+ depends on NETFILTER_TPROXY
+ depends on NETFILTER_XTABLES
+ select NF_DEFRAG_IPV4
+ help
+ This option adds a `socket' match, which can be used to match
+ packets for which a TCP or UDP socket lookup finds a valid socket.
+ It can only be used in the tproxy table.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_MATCH_STATE
tristate '"state" match support'
depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 76e16ea..7d7dbd6 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_PKTTYPE) += xt_pkttype.o
obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA) += xt_quota.o
obj-$(CONFIG_NETFILTER_XT_MATCH_REALM) += xt_realm.o
obj-$(CONFIG_NETFILTER_XT_MATCH_SCTP) += xt_sctp.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_SOCKET) += xt_socket.o
obj-$(CONFIG_NETFILTER_XT_MATCH_STATE) += xt_state.o
obj-$(CONFIG_NETFILTER_XT_MATCH_STATISTIC) += xt_statistic.o
obj-$(CONFIG_NETFILTER_XT_MATCH_STRING) += xt_string.o
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
new file mode 100644
index 0000000..285dfa8
--- /dev/null
+++ b/net/netfilter/xt_socket.c
@@ -0,0 +1,83 @@
+/*
+ * Transparent proxy support for Linux/iptables
+ *
+ * Copyright (C) 2007 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 <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+#include <net/sock.h>
+#include <net/inet_sock.h>
+#include <net/netfilter/nf_tproxy_core.h>
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+
+static bool
+socket_match(const struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const struct xt_match *match,
+ const void *matchinfo,
+ int offset,
+ unsigned int protoff,
+ bool *hotdrop)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct udphdr _hdr, *hp;
+ struct sock *sk;
+
+ /* TCP/UDP only */
+ if (iph->protocol != IPPROTO_TCP && iph->protocol != IPPROTO_UDP)
+ return false;
+
+ hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return false;
+
+ sk = nf_tproxy_get_sock_v4(iph->protocol,
+ iph->saddr, iph->daddr,
+ hp->source, hp->dest, in, false);
+ if (sk != NULL)
+ nf_tproxy_put_sock(sk);
+
+ pr_debug("socket match: proto %u %08x:%u -> %08x:%u sock %p\n",
+ iph->protocol, ntohl(iph->saddr), ntohs(hp->source),
+ ntohl(iph->daddr), ntohs(hp->dest), sk);
+
+ return (sk != NULL);
+}
+
+static struct xt_match xt_socket_reg __read_mostly = {
+ .name = "socket",
+ .family = AF_INET,
+ .match = socket_match,
+ .hooks = (1 << NF_IP_PRE_ROUTING),
+ .me = THIS_MODULE,
+};
+
+static int __init xt_socket_init(void)
+{
+ nf_defrag_ipv4_enable();
+ return xt_register_match(&xt_socket_reg);
+}
+
+static void __exit xt_socket_fini(void)
+{
+ xt_unregister_match(&xt_socket_reg);
+}
+
+module_init(xt_socket_init);
+module_exit(xt_socket_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Krisztian Kovacs");
+MODULE_DESCRIPTION("x_tables socket match module");
+MODULE_ALIAS("ipt_socket");
-
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