netfilter: bitwise: add NFTA_BITWISE_OP netlink attribute.

Add a new bitwise netlink attribute, NFTA_BITWISE_OP, which is set to a
value of a new enum, nft_bitwise_ops.  It describes the type of
operation an expression contains.  Currently, it only has one value:
NFT_BITWISE_BOOL.  More values will be added later to implement shifts.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -484,6 +484,16 @@ enum nft_immediate_attributes {
 };
 #define NFTA_IMMEDIATE_MAX	(__NFTA_IMMEDIATE_MAX - 1)
 
+/**
+ * enum nft_bitwise_ops - nf_tables bitwise operations
+ *
+ * @NFT_BITWISE_BOOL: mask-and-xor operation used to implement NOT, AND, OR and
+ *                    XOR boolean operations
+ */
+enum nft_bitwise_ops {
+	NFT_BITWISE_BOOL,
+};
+
 /**
  * enum nft_bitwise_attributes - nf_tables bitwise expression netlink attributes
  *
@@ -492,6 +502,7 @@ enum nft_immediate_attributes {
  * @NFTA_BITWISE_LEN: length of operands (NLA_U32)
  * @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)
  *
  * The bitwise expression performs the following operation:
  *
@@ -512,6 +523,7 @@ enum nft_bitwise_attributes {
 	NFTA_BITWISE_LEN,
 	NFTA_BITWISE_MASK,
 	NFTA_BITWISE_XOR,
+	NFTA_BITWISE_OP,
 	__NFTA_BITWISE_MAX
 };
 #define NFTA_BITWISE_MAX	(__NFTA_BITWISE_MAX - 1)

net/netfilter/nft_bitwise.c

@@ -18,6 +18,7 @@
 struct nft_bitwise {
 	enum nft_registers	sreg:8;
 	enum nft_registers	dreg:8;
+	enum nft_bitwise_ops	op:8;
 	u8			len;
 	struct nft_data		mask;
 	struct nft_data		xor;
@@ -41,6 +42,7 @@ static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
 	[NFTA_BITWISE_LEN]	= { .type = NLA_U32 },
 	[NFTA_BITWISE_MASK]	= { .type = NLA_NESTED },
 	[NFTA_BITWISE_XOR]	= { .type = NLA_NESTED },
+	[NFTA_BITWISE_OP]	= { .type = NLA_U32 },
 };
 
 static int nft_bitwise_init(const struct nft_ctx *ctx,
@@ -76,6 +78,18 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
 	if (err < 0)
 		return err;
 
+	if (tb[NFTA_BITWISE_OP]) {
+		priv->op = ntohl(nla_get_be32(tb[NFTA_BITWISE_OP]));
+		switch (priv->op) {
+		case NFT_BITWISE_BOOL:
+			break;
+		default:
+			return -EOPNOTSUPP;
+		}
+	} else {
+		priv->op = NFT_BITWISE_BOOL;
+	}
+
 	err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
 			    tb[NFTA_BITWISE_MASK]);
 	if (err < 0)
@@ -112,6 +126,8 @@ static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
 		return -1;
 	if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
 		return -1;
+	if (nla_put_be32(skb, NFTA_BITWISE_OP, htonl(priv->op)))
+		return -1;
 
 	if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
 			  NFT_DATA_VALUE, priv->len) < 0)