[NETFILTER]: ebt_mark: add or/and/xor action support to mark target

The following patch adds or/and/xor functionality for the mark target,
while staying backwards compatible.
Signed-off-by: Bart De Schuymer <bdschuym@pandora.be>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter_bridge/ebt_mark_t.h

 #ifndef __LINUX_BRIDGE_EBT_MARK_T_H
 #define __LINUX_BRIDGE_EBT_MARK_T_H
 
+/* The target member is reused for adding new actions, the
+ * value of the real target is -1 to -NUM_STANDARD_TARGETS.
+ * For backward compatibility, the 4 lsb (2 would be enough,
+ * but let's play it safe) are kept to designate this target.
+ * The remaining bits designate the action. By making the set
+ * action 0xfffffff0, the result will look ok for older
+ * versions. [September 2006] */
+#define MARK_SET_VALUE (0xfffffff0)
+#define MARK_OR_VALUE  (0xffffffe0)
+#define MARK_AND_VALUE (0xffffffd0)
+#define MARK_XOR_VALUE (0xffffffc0)
+
 struct ebt_mark_t_info
 {
 	unsigned long mark;

net/bridge/netfilter/ebt_mark.c

@@ -22,24 +22,37 @@ static int ebt_target_mark(struct sk_buff **pskb, unsigned int hooknr,
    const void *data, unsigned int datalen)
 {
 	struct ebt_mark_t_info *info = (struct ebt_mark_t_info *)data;
+	int action = info->target & -16;
 
-	if ((*pskb)->nfmark != info->mark)
+	if (action == MARK_SET_VALUE)
 		(*pskb)->nfmark = info->mark;
+	else if (action == MARK_OR_VALUE)
+		(*pskb)->nfmark |= info->mark;
+	else if (action == MARK_AND_VALUE)
+		(*pskb)->nfmark &= info->mark;
+	else
+		(*pskb)->nfmark ^= info->mark;
 
-	return info->target;
+	return info->target | -16;
 }
 
 static int ebt_target_mark_check(const char *tablename, unsigned int hookmask,
    const struct ebt_entry *e, void *data, unsigned int datalen)
 {
 	struct ebt_mark_t_info *info = (struct ebt_mark_t_info *)data;
+	int tmp;
 
 	if (datalen != EBT_ALIGN(sizeof(struct ebt_mark_t_info)))
 		return -EINVAL;
-	if (BASE_CHAIN && info->target == EBT_RETURN)
+	tmp = info->target | -16;
+	if (BASE_CHAIN && tmp == EBT_RETURN)
 		return -EINVAL;
 	CLEAR_BASE_CHAIN_BIT;
-	if (INVALID_TARGET)
+	if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
+		return -EINVAL;
+	tmp = info->target & -16;
+	if (tmp != MARK_SET_VALUE && tmp != MARK_OR_VALUE &&
+	    tmp != MARK_AND_VALUE && tmp != MARK_XOR_VALUE)
 		return -EINVAL;
 	return 0;
 }