1 files changed, 123 insertions, 0 deletions
diff --git a/kernel/linux/net/bridge/netfilter/ebt_among.c b/kernel/linux/net/bridge/netfilter/ebt_among.c
new file mode 100644
index 0000000..e69246a
--- /dev/null
+++ b/kernel/linux/net/bridge/netfilter/ebt_among.c
@@ -0,0 +1,123 @@
+/*
+ *  ebt_among
+ *
+ *	Authors:
+ *	Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
+ *
+ *  August, 2003
+ *
+ */
+
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_bridge/ebt_among.h>
+#include <linux/module.h>
+
+static int ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh, const char *mac)
+{
+	/* You may be puzzled as to how this code works.
+	 * Some tricks were used, refer to include/linux/netfilter_bridge/ebt_among.h
+	 * as there you can find a solution of this mystery.
+	 */
+	const struct ebt_mac_wormhash_tuple *p;
+	int offset;
+	const char *base = (const char*)wh;
+	uint32_t cmp[2] = { 0, 0 };
+	int key = (const unsigned char)mac[5];
+	memcpy(((char*)cmp)+2, mac, 6);
+	offset = wh->table[key];
+	while (offset) {
+		p = (const struct ebt_mac_wormhash_tuple*)(base + offset);
+		if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
+			return 1;
+		offset = p->next_ofs;
+	}
+	return 0;
+}
+
+static int ebt_mac_wormhash_check_integrity(const struct ebt_mac_wormhash *wh)
+{
+	int i, count;
+	const struct ebt_mac_wormhash_tuple *p;
+	int offset;
+	const char *base = (const char*)wh;
+	
+	count = 0;
+	for (i=256; i--;) {
+		offset = wh->table[i];
+		while (offset) {
+			p = (const struct ebt_mac_wormhash_tuple*)(base + offset);
+			if (p < wh->pool)
+				return -1;
+			if (p > wh->pool + 256 - 1)
+				return -2;
+			count++;
+			if (count > 1000)
+				return -3;
+			offset = p->next_ofs;
+		}
+	}
+	return 0;
+}
+
+static int ebt_filter_among(const struct sk_buff *skb,
+   const struct net_device *in, const struct net_device *out, const void *data,
+   unsigned int datalen)
+{
+	struct ebt_among_info *info = (struct ebt_among_info *) data;
+
+	const char *dmac, *smac;
+	if (info->bitmask & EBT_AMONG_SRC) {
+		smac = skb->mac.ethernet->h_source;
+		if (!ebt_mac_wormhash_contains(&info->wh_src, smac))
+			return EBT_NOMATCH;
+	}
+
+	if (info->bitmask & EBT_AMONG_DST) {
+		dmac = skb->mac.ethernet->h_dest;
+		if (!ebt_mac_wormhash_contains(&info->wh_dst, dmac))
+			return EBT_NOMATCH;
+	}
+
+	return EBT_MATCH;
+}
+
+static int ebt_among_check(const char *tablename, unsigned int hookmask,
+   const struct ebt_entry *e, void *data, unsigned int datalen)
+{
+	struct ebt_among_info *info = (struct ebt_among_info *) data;
+
+	if (datalen != EBT_ALIGN(sizeof(struct ebt_among_info))) {
+		printk(KERN_WARNING "ebtables: among: wrong size\n");
+		return -EINVAL;
+	}
+	if ((info->bitmask & EBT_AMONG_DST) && ebt_mac_wormhash_check_integrity(&info->wh_dst)) {
+		printk(KERN_WARNING "ebtables: among: dst integrity fail\n");
+		return -EINVAL;
+	}
+	if ((info->bitmask & EBT_AMONG_SRC) && ebt_mac_wormhash_check_integrity(&info->wh_src)) {
+		printk(KERN_WARNING "ebtables: among: src integrity fail\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static struct ebt_match filter_among =
+{
+	{NULL, NULL}, EBT_AMONG_MATCH, ebt_filter_among, ebt_among_check, NULL,
+	THIS_MODULE
+};
+
+static int __init init(void)
+{
+	return ebt_register_match(&filter_among);
+}
+
+static void __exit fini(void)
+{
+	ebt_unregister_match(&filter_among);
+}
+
+module_init(init);
+module_exit(fini);
+EXPORT_NO_SYMBOLS;
+MODULE_LICENSE("GPL");