[next,v2] iptables: add xt_bpf match

diff --git a/Gconfig.xt_bpf b/Gconfig.xt_bpf
new file mode 100644
index 0000000..dd51452
--- /dev/null
+++ b/Gconfig.xt_bpf
@@ -0,0 +1 @@ 
+CONFIG_NETFILTER_XT_MATCH_BPF=m
diff --git a/include/uapi/linux/netfilter/xt_bpf.h b/include/uapi/linux/netfilter/xt_bpf.h
new file mode 100644
index 0000000..5dda450
--- /dev/null
+++ b/include/uapi/linux/netfilter/xt_bpf.h
@@ -0,0 +1,17 @@ 
+#ifndef _XT_BPF_H
+#define _XT_BPF_H
+
+#include <linux/filter.h>
+#include <linux/types.h>
+
+#define XT_BPF_MAX_NUM_INSTR	64
+
+struct xt_bpf_info {
+	__u16 bpf_program_num_elem;
+	struct sock_filter bpf_program[XT_BPF_MAX_NUM_INSTR];
+
+	/* only used in the kernel */
+	struct sk_filter *filter __attribute__((aligned(8)));
+};
+
+#endif /*_XT_BPF_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index fefa514..d45720f 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -798,6 +798,15 @@  config NETFILTER_XT_MATCH_ADDRTYPE
 	  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_BPF
+	tristate '"bpf" match support'
+	depends on NETFILTER_ADVANCED
+	help
+	  BPF matching applies a linux socket filter to each packet and
+          accepts those for which the filter returns non-zero.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
 config NETFILTER_XT_MATCH_CLUSTER
 	tristate '"cluster" match support'
 	depends on NF_CONNTRACK
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 3259697..6d6194525 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -98,6 +98,7 @@  obj-$(CONFIG_NETFILTER_XT_TARGET_IDLETIMER) += xt_IDLETIMER.o
 
 # matches
 obj-$(CONFIG_NETFILTER_XT_MATCH_ADDRTYPE) += xt_addrtype.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_BPF) += xt_bpf.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_CLUSTER) += xt_cluster.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_CONNBYTES) += xt_connbytes.o
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 8d987c3..26306be 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -379,8 +379,9 @@  int xt_check_match(struct xt_mtchk_param *par,
 	if (XT_ALIGN(par->match->matchsize) != size &&
 	    par->match->matchsize != -1) {
 		/*
-		 * ebt_among is exempt from centralized matchsize checking
-		 * because it uses a dynamic-size data set.
+		 * matches of variable size length, such as ebt_among,
+		 * are exempt from centralized matchsize checking. They
+		 * skip the test by setting xt_match.matchsize to -1.
 		 */
 		pr_err("%s_tables: %s.%u match: invalid size "
 		       "%u (kernel) != (user) %u\n",
diff --git a/net/netfilter/xt_bpf.c b/net/netfilter/xt_bpf.c
new file mode 100644
index 0000000..1bdfab8
--- /dev/null
+++ b/net/netfilter/xt_bpf.c
@@ -0,0 +1,73 @@ 
+/* Xtables module to match packets using a BPF filter.
+ * Copyright 2013 Google Inc.
+ * Written by Willem de Bruijn <willemb@google.com>
+ *
+ * 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/ipv6.h>
+#include <linux/filter.h>
+#include <net/ip.h>
+
+#include <linux/netfilter/xt_bpf.h>
+#include <linux/netfilter/x_tables.h>
+
+MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
+MODULE_DESCRIPTION("Xtables: BPF filter match");
+MODULE_LICENSE("GPL");
+
+static int bpf_mt_check(const struct xt_mtchk_param *par)
+{
+	struct xt_bpf_info *info = par->matchinfo;
+	struct sock_fprog program;
+
+	program.len = info->bpf_program_num_elem;
+	program.filter = info->bpf_program;
+	if (sk_unattached_filter_create(&info->filter, &program)) {
+		pr_info("bpf: check failed: parse error\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	const struct xt_bpf_info *info = par->matchinfo;
+
+	return SK_RUN_FILTER(info->filter, skb);
+}
+
+static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
+{
+	const struct xt_bpf_info *info = par->matchinfo;
+	sk_unattached_filter_destroy(info->filter);
+}
+
+static struct xt_match bpf_mt_reg __read_mostly = {
+	.name		= "bpf",
+	.revision	= 0,
+	.family		= NFPROTO_UNSPEC,
+	.checkentry	= bpf_mt_check,
+	.match		= bpf_mt,
+	.destroy	= bpf_mt_destroy,
+	.matchsize	= sizeof(struct xt_bpf_info),
+	.me		= THIS_MODULE,
+};
+
+static int __init bpf_mt_init(void)
+{
+	return xt_register_match(&bpf_mt_reg);
+}
+
+static void __exit bpf_mt_exit(void)
+{
+	xt_unregister_match(&bpf_mt_reg);
+}
+
+module_init(bpf_mt_init);
+module_exit(bpf_mt_exit);