1 files changed, 113 insertions, 0 deletions
diff --git a/net/netfilter/xt_esp.c b/net/netfilter/xt_esp.c
new file mode 100644
index 0000000..6094399
--- /dev/null
+++ b/net/netfilter/xt_esp.c
@@ -0,0 +1,113 @@
+/* Kernel module to match ESP parameters. */
+
+/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
+ *
+ * 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/in.h>
+#include <linux/ip.h>
+
+#include <linux/netfilter/xt_esp.h>
+#include <linux/netfilter/x_tables.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
+MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");
+MODULE_ALIAS("ipt_esp");
+MODULE_ALIAS("ip6t_esp");
+
+#if 0
+#define duprintf(format, args...) printk(format , ## args)
+#else
+#define duprintf(format, args...)
+#endif
+
+/* Returns 1 if the spi is matched by the range, 0 otherwise */
+static inline bool
+spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
+{
+	bool r;
+	duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
+		 min, spi, max);
+	r = (spi >= min && spi <= max) ^ invert;
+	duprintf(" result %s\n", r ? "PASS" : "FAILED");
+	return r;
+}
+
+static bool esp_mt(const struct sk_buff *skb, const struct xt_match_param *par)
+{
+	const struct ip_esp_hdr *eh;
+	struct ip_esp_hdr _esp;
+	const struct xt_esp *espinfo = par->matchinfo;
+
+	/* Must not be a fragment. */
+	if (par->fragoff != 0)
+		return false;
+
+	eh = skb_header_pointer(skb, par->thoff, sizeof(_esp), &_esp);
+	if (eh == NULL) {
+		/* We've been asked to examine this packet, and we
+		 * can't.  Hence, no choice but to drop.
+		 */
+		duprintf("Dropping evil ESP tinygram.\n");
+		*par->hotdrop = true;
+		return false;
+	}
+
+	return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
+			 !!(espinfo->invflags & XT_ESP_INV_SPI));
+}
+
+static bool esp_mt_check(const struct xt_mtchk_param *par)
+{
+	const struct xt_esp *espinfo = par->matchinfo;
+
+	if (espinfo->invflags & ~XT_ESP_INV_MASK) {
+		duprintf("xt_esp: unknown flags %X\n", espinfo->invflags);
+		return false;
+	}
+
+	return true;
+}
+
+static struct xt_match esp_mt_reg[] __read_mostly = {
+	{
+		.name		= "esp",
+		.family		= NFPROTO_IPV4,
+		.checkentry	= esp_mt_check,
+		.match		= esp_mt,
+		.matchsize	= sizeof(struct xt_esp),
+		.proto		= IPPROTO_ESP,
+		.me		= THIS_MODULE,
+	},
+	{
+		.name		= "esp",
+		.family		= NFPROTO_IPV6,
+		.checkentry	= esp_mt_check,
+		.match		= esp_mt,
+		.matchsize	= sizeof(struct xt_esp),
+		.proto		= IPPROTO_ESP,
+		.me		= THIS_MODULE,
+	},
+};
+
+static int __init esp_mt_init(void)
+{
+	return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
+}
+
+static void __exit esp_mt_exit(void)
+{
+	xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
+}
+
+module_init(esp_mt_init);
+module_exit(esp_mt_exit);