netfilter: bitwise: only offload boolean operations.

Only boolean operations supports offloading, so check the type of the
operation and return an error for other types.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_bitwise.c

@@ -189,6 +189,9 @@ static int nft_bitwise_offload(struct nft_offload_ctx *ctx,
 	const struct nft_bitwise *priv = nft_expr_priv(expr);
 	struct nft_offload_reg *reg = &ctx->regs[priv->dreg];
 
+	if (priv->op != NFT_BITWISE_BOOL)
+		return -EOPNOTSUPP;
+
 	if (memcmp(&priv->xor, &zero, sizeof(priv->xor)) ||
 	    priv->sreg != priv->dreg || priv->len != reg->len)
 		return -EOPNOTSUPP;