1 files changed, 70 insertions, 0 deletions
diff --git a/net/netfilter/xt_length.c b/net/netfilter/xt_length.c
new file mode 100644
index 0000000..c4871ca
--- /dev/null
+++ b/net/netfilter/xt_length.c
@@ -0,0 +1,70 @@
+/* Kernel module to match packet length. */
+/* (C) 1999-2001 James Morris <jmorros@intercode.com.au>
+ *
+ * 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 <net/ip.h>
+
+#include <linux/netfilter/xt_length.h>
+#include <linux/netfilter/x_tables.h>
+
+MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
+MODULE_DESCRIPTION("Xtables: Packet length (Layer3,4,5) match");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_length");
+MODULE_ALIAS("ip6t_length");
+
+static bool
+length_mt(const struct sk_buff *skb, const struct xt_match_param *par)
+{
+	const struct xt_length_info *info = par->matchinfo;
+	u_int16_t pktlen = ntohs(ip_hdr(skb)->tot_len);
+
+	return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
+}
+
+static bool
+length_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
+{
+	const struct xt_length_info *info = par->matchinfo;
+	const u_int16_t pktlen = ntohs(ipv6_hdr(skb)->payload_len) +
+				 sizeof(struct ipv6hdr);
+
+	return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
+}
+
+static struct xt_match length_mt_reg[] __read_mostly = {
+	{
+		.name		= "length",
+		.family		= NFPROTO_IPV4,
+		.match		= length_mt,
+		.matchsize	= sizeof(struct xt_length_info),
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "length",
+		.family		= NFPROTO_IPV6,
+		.match		= length_mt6,
+		.matchsize	= sizeof(struct xt_length_info),
+		.me		= THIS_MODULE,
+	},
+};
+
+static int __init length_mt_init(void)
+{
+	return xt_register_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
+}
+
+static void __exit length_mt_exit(void)
+{
+	xt_unregister_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
+}
+
+module_init(length_mt_init);
+module_exit(length_mt_exit);