netfilter: bitwise: add NFTA_BITWISE_DATA attribute.

Add a new bitwise netlink attribute that will be used by shift
operations to store the size of the shift.  It is not used by boolean
operations.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -503,6 +503,8 @@ enum nft_bitwise_ops {
  * @NFTA_BITWISE_MASK: mask value (NLA_NESTED: nft_data_attributes)
  * @NFTA_BITWISE_XOR: xor value (NLA_NESTED: nft_data_attributes)
  * @NFTA_BITWISE_OP: type of operation (NLA_U32: nft_bitwise_ops)
+ * @NFTA_BITWISE_DATA: argument for non-boolean operations
+ *                     (NLA_NESTED: nft_data_attributes)
  *
  * The bitwise expression performs the following operation:
  *
@@ -524,6 +526,7 @@ enum nft_bitwise_attributes {
 	NFTA_BITWISE_MASK,
 	NFTA_BITWISE_XOR,
 	NFTA_BITWISE_OP,
+	NFTA_BITWISE_DATA,
 	__NFTA_BITWISE_MAX
 };
 #define NFTA_BITWISE_MAX	(__NFTA_BITWISE_MAX - 1)

net/netfilter/nft_bitwise.c

@@ -22,6 +22,7 @@ struct nft_bitwise {
 	u8			len;
 	struct nft_data		mask;
 	struct nft_data		xor;
+	struct nft_data		data;
 };
 
 static void nft_bitwise_eval_bool(u32 *dst, const u32 *src,
@@ -54,6 +55,7 @@ static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
 	[NFTA_BITWISE_MASK]	= { .type = NLA_NESTED },
 	[NFTA_BITWISE_XOR]	= { .type = NLA_NESTED },
 	[NFTA_BITWISE_OP]	= { .type = NLA_U32 },
+	[NFTA_BITWISE_DATA]	= { .type = NLA_NESTED },
 };
 
 static int nft_bitwise_init_bool(struct nft_bitwise *priv,
@@ -62,6 +64,9 @@ static int nft_bitwise_init_bool(struct nft_bitwise *priv,
 	struct nft_data_desc d1, d2;
 	int err;
 
+	if (tb[NFTA_BITWISE_DATA])
+		return -EINVAL;
+
 	if (!tb[NFTA_BITWISE_MASK] ||
 	    !tb[NFTA_BITWISE_XOR])
 		return -EINVAL;