Supplemental lesson - Dynamic security

Άρθρο
12/09/2022

Applies to: SQL Server 2017 and later Analysis Services Azure Analysis Services Fabric/Power BI Premium

In this supplemental lesson, you create an additional role that implements dynamic security. Dynamic security provides row-level security based on the user name or login id of the user currently logged on.

To implement dynamic security, you add a table to your model containing the user names of those users that can connect to the model and browse model objects and data. The model you create using this tutorial is in the context of Adventure Works; however, to complete this lesson, you must add a table containing users from your own domain. You do not need the passwords for the user names that are added. To create an EmployeeSecurity table, with a small sample of users from your own domain, you use the Paste feature, pasting employee data from an Excel spreadsheet. In a real-world scenario, the table containing user names would typically be a table from an actual database as a data source; for example, a real DimEmployee table.

To implement dynamic security, you use two DAX functions: USERNAME Function (DAX) and LOOKUPVALUE Function (DAX). These functions, applied in a row filter formula, are defined in a new role. By using the LOOKUPVALUE function, the formula specifies a value from the EmployeeSecurity table. The formula then passes that value to the USERNAME function, which specifies the user name of the user logged on belongs to this role. The user can then browse only data specified by the role's row filters. In this scenario, you specify that sales employees can only browse Internet sales data for the sales territories in which they are a member.

Those tasks that are unique to this Adventure Works tabular model scenario, but would not necessarily apply to a real-world scenario are identified as such. Each task includes additional information describing the purpose of the task.

Estimated time to complete this lesson: 30 minutes

Prerequisites

This supplemental lesson article is part of a tabular modeling tutorial, which should be completed in order. Before performing the tasks in this supplemental lesson, you should have completed all previous lessons.

Add the DimSalesTerritory table to the AW Internet Sales Tabular Model Project

To implement dynamic security for this Adventure Works scenario, you must add two additional tables to your model. The first table you add is DimSalesTerritory (as Sales Territory) from the same AdventureWorksDW database. You later apply a row filter to the SalesTerritory table that defines the particular data the logged on user can browse.

To add the DimSalesTerritory table

In Tabular Model Explorer > Data Sources, right-click your connection, and then click Import New Tables.

If the Impersonation Credentials dialog box appears, type the impersonation credentials you used in Lesson 2: Add Data.
In Navigator, select the DimSalesTerritory table, and then click OK.
In Query Editor, click the DimSalesTerritory query, and then remove SalesTerritoryAlternateKey column.
Click Import.

The new table is added to the model workspace. Objects and data from the source DimSalesTerritory table are then imported into your AW Internet Sales Tabular Model.
After the table has been imported successfully, click Close.

Add a table with user name data

The DimEmployee table in the AdventureWorksDW sample database contains users from the AdventureWorks domain. Those user names do not exist in your own environment. You must create a table in your model that contains a small sample (at least three) of actual users from your organization. You then add these users as members to the new role. You do not need the passwords for the sample user names, but you do need actual Windows user names from your own domain.

To add an EmployeeSecurity table

Open Microsoft Excel, creating a worksheet.

Copy the following table, including the header row, and then paste it into the worksheet.

  |EmployeeId|SalesTerritoryId|FirstName|LastName|LoginId|  
  |---------------|----------------------|--------------|-------------|------------|  
  |1|2|<user first name>|<user last name>|\<domain\username>|  
  |1|3|<user first name>|<user last name>|\<domain\username>|  
  |2|4|<user first name>|<user last name>|\<domain\username>|  
  |3|5|<user first name>|<user last name>|\<domain\username>|

Replace the first name, last name, and domain\username with the names and login ids of three users in your organization. Put the same user on the first two rows, for EmployeeId 1, showing this user belongs to more than one sales territory. Leave the EmployeeId and SalesTerritoryId fields as they are.
Save the worksheet as SampleEmployee.
In the worksheet, select all the cells with employee data, including the headers, then right-click the selected data, and then click Copy.
In SSDT, click the Edit menu, and then click Paste.

If Paste is grayed out, click any column in any table in the model designer window, and try again.
In the Paste Preview dialog box, in Table Name, type EmployeeSecurity.
In Data to be pasted, verify the data includes all the user data and headers from the SampleEmployee worksheet.
Verify Use first row as column headers is checked, and then click Ok.

A new table named EmployeeSecurity with employee data copied from the SampleEmployee worksheet is created.

Create relationships between FactInternetSales, DimGeography, and DimSalesTerritory table

The FactInternetSales, DimGeography, and DimSalesTerritory table all contain a common column, SalesTerritoryId. The SalesTerritoryId column in the DimSalesTerritory table contains values with a different Id for each sales territory.

To create relationships between the FactInternetSales, DimGeography, and the DimSalesTerritory table

In Diagram View, in the DimGeography table, click, and hold on the SalesTerritoryId column, then drag the cursor to the SalesTerritoryId column in the DimSalesTerritory table, and then release.
In the FactInternetSales table, click, and hold on the SalesTerritoryId column, then drag the cursor to the SalesTerritoryId column in the DimSalesTerritory table, and then release.

Notice the Active property for this relationship is False, meaning it's inactive. The FactInternetSales table already has another active relationship.

Hide the EmployeeSecurity Table from client applications

In this task, you hide the EmployeeSecurity table, keeping it from appearing in a client application's field list. Keep in mind that hiding a table does not secure it. Users can still query EmployeeSecurity table data if they know how. To secure the EmployeeSecurity table data, preventing users from being able to query any of its data, you apply a filter in a later task.

To hide the EmployeeSecurity table from client applications

In the model designer, in Diagram View, right-click the Employee table heading, and then click Hide from Client Tools.

Create a Sales Employees by Territory user role

In this task, you create a user role. This role includes a row filter defining which rows of the DimSalesTerritory table are visible to users. The filter is then applied in the one-to-many relationship direction to all other tables related to DimSalesTerritory. You also apply a filter that secures the entire EmployeeSecurity table from being queryable by any user that is a member of the role.

Note

The Sales Employees by Territory role you create in this lesson restricts members to browse (or query) only sales data for the sales territory to which they belong. If you add a user as a member to the Sales Employees by Territory role that also exists as a member in a role created in Lesson 11: Create Roles, you get a combination of permissions. When a user is a member of multiple roles, the permissions, and row filters defined for each role are cumulative. That is, the user has the greater permissions determined by the combination of roles.

To create a Sales Employees by Territory user role

In SSDT, click the Model menu, and then click Roles.
In Role Manager, click New.

A new role with the None permission is added to the list.
Click the new role, and then in the Name column, rename the role to Sales Employees by Territory.
In the Permissions column, click the dropdown list, and then select the Read permission.
Click the Members tab, and then click Add.
In the Select User or Group dialog box, in Enter the object named to select, type the first sample user name you used when creating the EmployeeSecurity table. Click Check Names to verify the user name is valid, and then click Ok.

Repeat this step, adding the other sample user names you used when creating the EmployeeSecurity table.
Click the Row Filters tab.
For the EmployeeSecurity table, in the DAX Filter column, type the following formula:
```
  =FALSE()  
```
This formula specifies that all columns resolve to the false Boolean condition. No columns for the EmployeeSecurity table can be queried by a member of the Sales Employees by Territory user role.
For the DimSalesTerritory table, type the following formula:
```
='DimSalesTerritory'[SalesTerritoryKey]=LOOKUPVALUE('EmployeeSecurity'[SalesTerritoryId], 
  'EmployeeSecurity'[LoginId], USERNAME(), 
  'EmployeeSecurity'[SalesTerritoryId], 'DimSalesTerritory'[SalesTerritoryKey]) 
```
In this formula, the LOOKUPVALUE function returns all values for the DimEmployeeSecurity[SalesTerritoryId] column, where the EmployeeSecurity[LoginId] is the same as the current logged on Windows user name, and EmployeeSecurity[SalesTerritoryId] is the same as the DimSalesTerritory[SalesTerritoryId].

The set of sales territory IDs returned by LOOKUPVALUE is then used to restrict the rows shown in the DimSalesTerritory table. Only rows where the SalesTerritoryID for the row is in the set of IDs returned by the LOOKUPVALUE function are displayed.
In Role Manager, click Ok.

Test the Sales Employees by Territory User Role

In this task, you use the Analyze in Excel feature in SSDT to test the efficacy of the Sales Employees by Territory user role. You specify one of the user names you added to the EmployeeSecurity table and as a member of the role. This user name is then used as the effective user name in the connection created between Excel and the model.

To test the Sales Employees by Territory user role

In SSDT, click the Model menu, and then click Analyze in Excel.
In the Analyze in Excel dialog box, in Specify the user name or role to use to connect to the model, select Other Windows User, and then click Browse.
In the Select User or Group dialog box, in Enter the object name to select, type a user name you included in the EmployeeSecurity table, and then click Check Names.
Click Ok to close the Select User or Group dialog box, and then click Ok to close the Analyze in Excel dialog box.

Excel opens with a new workbook. A PivotTable is automatically created. The PivotTable Fields list includes most of the data fields available in your new model.

Notice the EmployeeSecurity table is not visible in the PivotTable Fields list. You hid this table from client tools in a previous task.
In the Fields list, in ∑ Internet Sales (measures), select the InternetTotalSales measure. The measure is entered into the Values fields.
Select the SalesTerritoryId column from the DimSalesTerritory table. The column is entered into the Row Labels fields.

Notice Internet sales figures appear only for the one region to which the effective user name you used belongs. If you select another column, like City from the DimGeography table as Row Label field, only cities in the sales territory to which the effective user belongs are displayed.
This user cannot browse or query any Internet sales data for territories other than the one they belong to. This restriction is because the row filter defined for the DimSalesTerritory table, in the Sales Employees by Territory user role, secures data for all data related to other sales territories.

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