netfilter: bitwise: add helper for initializing boolean operations.

Split the code specific to initializing bitwise boolean operations out
into a separate function.  A similar function will be added later for
shift operations.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_bitwise.c

@@ -45,20 +45,53 @@ static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
 	[NFTA_BITWISE_OP]	= { .type = NLA_U32 },
 };
 
+static int nft_bitwise_init_bool(struct nft_bitwise *priv,
+				 const struct nlattr *const tb[])
+{
+	struct nft_data_desc d1, d2;
+	int err;
+
+	if (!tb[NFTA_BITWISE_MASK] ||
+	    !tb[NFTA_BITWISE_XOR])
+		return -EINVAL;
+
+	err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
+			    tb[NFTA_BITWISE_MASK]);
+	if (err < 0)
+		return err;
+	if (d1.type != NFT_DATA_VALUE || d1.len != priv->len) {
+		err = -EINVAL;
+		goto err1;
+	}
+
+	err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
+			    tb[NFTA_BITWISE_XOR]);
+	if (err < 0)
+		goto err1;
+	if (d2.type != NFT_DATA_VALUE || d2.len != priv->len) {
+		err = -EINVAL;
+		goto err2;
+	}
+
+	return 0;
+err2:
+	nft_data_release(&priv->xor, d2.type);
+err1:
+	nft_data_release(&priv->mask, d1.type);
+	return err;
+}
+
 static int nft_bitwise_init(const struct nft_ctx *ctx,
 			    const struct nft_expr *expr,
 			    const struct nlattr * const tb[])
 {
 	struct nft_bitwise *priv = nft_expr_priv(expr);
-	struct nft_data_desc d1, d2;
 	u32 len;
 	int err;
 
 	if (!tb[NFTA_BITWISE_SREG] ||
 	    !tb[NFTA_BITWISE_DREG] ||
-	    !tb[NFTA_BITWISE_LEN]  ||
-	    !tb[NFTA_BITWISE_MASK] ||
-	    !tb[NFTA_BITWISE_XOR])
+	    !tb[NFTA_BITWISE_LEN])
 		return -EINVAL;
 
 	err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
@@ -90,29 +123,12 @@ static int nft_bitwise_init(const struct nft_ctx *ctx,
 		priv->op = NFT_BITWISE_BOOL;
 	}
 
-	err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
-			    tb[NFTA_BITWISE_MASK]);
-	if (err < 0)
-		return err;
-	if (d1.type != NFT_DATA_VALUE || d1.len != priv->len) {
-		err = -EINVAL;
-		goto err1;
-	}
-
-	err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
-			    tb[NFTA_BITWISE_XOR]);
-	if (err < 0)
-		goto err1;
-	if (d2.type != NFT_DATA_VALUE || d2.len != priv->len) {
-		err = -EINVAL;
-		goto err2;
+	switch(priv->op) {
+	case NFT_BITWISE_BOOL:
+		err = nft_bitwise_init_bool(priv, tb);
+		break;
 	}
 
-	return 0;
-err2:
-	nft_data_release(&priv->xor, d2.type);
-err1:
-	nft_data_release(&priv->mask, d1.type);
 	return err;
 }