Categories
Datawarehouse

SQL Server 2016 On-Premise with Row-Level Security with Active Directory (Part I)

In this article, I’ll explain a basic use case of Row-Level-Security implementation for Microsoft SQL Server 2016 database.

The AdventureWorks Database supports a fictitious, multinational manufacturing company called Adventure Works Cycles. This company sells products around the world. Sales are ordered from five different countries like Unites States, Germany, United Kingdom, Canada, France and Australia.

Adventure Works Cycles has Sales Teams in each of these countries. These teams should only access to data from their corresponding country.

In the picture below, we can see that Ginger Howell, a sales representative from the United States Sales Team, is trying to get information from the Customer Dimension table (Dim Customer).

When GHowell send the query: “SELECT * FROM DimCustomer” to the database. The DimCustomer table contains customer records not only from USA, but from other countries. The database should retrieve to GHowell only the records corresponding to United States Customers.

SQL Server 2016 introduced a new feature the database engine: Row-Level-Security. Row Level Security (RLS) is a concept that provides security at the table row level within the database layer, instead of at the application layer. RLS is accomplished by using a function (predicate) and the security policy that should be implemented by a database administrator.

We are going to use Adventure Works Database as a sample. You can download the database from this link: https://msftdbprodsamples.codeplex.com/releases/view/125550

Download and restore the Adventure Works DW 2014 Full Database Backup.zip

The following is a simplified diagram that includes only three tables from the Adventure Works database: DimCustomer, DimGeography and FactInternetSales

Now, we have Active directory groups corresponding to each country’s sales team.

We create a SQL Login for each of these Active Directory groups.

With the SQL Logins created, we can implement our security policy.

First, we create a new schema, just to keep SQL objects separate from the existing objects.

CREATE SCHEMA RLS

We create the function that we’ll use as a filter predicate for the security policy.

The predicate function is an inline table valued function. This function returns 1 when a row in the DimGeography table matches the corresponding CountryRegionCode (G.CountryRegionCode = ‘US’) and the user executing the query belongs to the corresponding Active Directory group (IS_MEMBER(‘DOMAIN\AW United States’) = 1).

CREATE FUNCTION RLS.GeographyAccessPredicate(@GeographyKey AS INT)

RETURNS TABLE

WITH SCHEMABINDING

AS

RETURN SELECT 1 AS AccessResult

FROM dbo.DimGeography G

WHERE

G.GeographyKey = @GeographyKey AND

(
 (
    G.CountryRegionCode = 'US' AND IS_MEMBER('DOMAIN\AW United States') = 1

  )
  OR

 (
    G.CountryRegionCode = 'GB' AND IS_MEMBER('DOMAIN\AW United Kingdom') = 1
 )
  OR
 (
     G.CountryRegionCode = 'DE' AND IS_MEMBER('DOMAIN\AW Germany') = 1
 )
  OR
  (
     G.CountryRegionCode = 'FR' AND IS_MEMBER('DOMAIN\AW France') = 1
   )
  OR
   (
     G.CountryRegionCode = 'CA' AND IS_MEMBER('DOMAIN\AW Canada') = 1
   )
  OR
  (
    G.CountryRegionCode = 'AU' AND IS_MEMBER('DOMAIN\AW Australia') = 1
  )
)
 

Finally, we add the function as filter predicate on the DimCustomer table:

CREATE SECURITY POLICY RLS.AWSecurityPolicy

ADD FILTER PREDICATE RLS.GeographyAccessPredicate(GeographyKey) ON dbo.DimCustomer

After this our Row-Level-Security is implemented!

Now, we’ll test it by running some scripts. We impersonate a user, GHowell, which belongs to the United States Active Directory.

EXECUTE AS LOGIN = 'DOMAIN\GHowell' -- United States Group

SELECT SUSER_NAME()

SELECT FirstName, LastName, EnglishCountryRegionName

FROM dbo.DimCustomer C

INNER JOIN dbo.DimGeography G

ON C.GeographyKey = G.GeographyKey

The query returns only customers from United States region as expected.

Execute the Revert command to return the execution context back to your user.

REVERT;

Now let’s see what happens behind scenes when the query is executed.

-- Show Plan without Security
GRANT SHOWPLAN TO [DOMAIN\Administrator]
GO
ALTER SECURITY POLICY RLS.AWSecurityPolicy WITH (STATE=OFF)
GO
SET SHOWPLAN_ALL ON
GO
SELECT COUNT(*) FROM DimCustomer
GO
SET SHOWPLAN_ALL OFF

The execution plan shows a simple scan to the DimCustomer table, when the security policy is off.

Now, let’s see how is the execution plan when the security policy is applied.

-- Show Plan with Security

ALTER SECURITY POLICY RLS.AWSecurityPolicy WITH (STATE=ON)
GO
SET SHOWPLAN_ALL ON
GO
SELECT COUNT(*) FROM DimCustomer
GO
SET SHOWPLAN_ALL OFF

When the security policy applied, the execution plan shows an extra join. The filter predicate is being applied and joined to the DimCustomer table.

There is an overhead when Row-Level-Security is applied. This impact in the performance of the queries is affected by the implementation of the filter predicate function.

In our filter predicate function GeographyAccessPredicate, there is a WHERE condition that slows down the query performance. The GeographyAccessPredicate function contains OR conditions for each country, which it will denied the use of indexes in the tables.

Second, we use the function called IS_MEMBER, which evaluate whether the current user is a member of the specified Active Directory group. This also will execute poorly when we query tables with millions rows.

In the next article, I will show a better approach for the predicate function, to speed up the query performance.

Categories
Datawarehouse Power BI

SQL Saturday Presentation – Data Security with Power BI, SSAS, SQL Server and Active Directory

Hector Villafuerte speaking on SQL Saturday South Florida

Saturday, Jun 10, 2017 Conference

http://notes.optimumclick.com/wp-content/uploads/sites/3/2017/06/RLS-SQL-Saturday-1.pptx

Categories
Datawarehouse Power BI

Bringing Security where data lives

The following is a series of articles that explain how we can use Row Level Security (RLS) and Active Directory across all BI technologies, database and tools in the corporate environment.

The goal is to create an integrated and a comprehensive data access control across multiple database technologies using different BI Tools or Apps.

SQL Server 2016 and Power BI started to support Row-Level-Security last year. RLS was already supported by SQL Server Analysis Services (SSAS) with Tabular and Multidimensional for some time.

The following picture shows some BI Tools and Databases used in the Microsoft BI Ecosystem.

On the top we have BI Tools used for authoring, publishing and hosting reports like:

  • Excel, number one BI Tool in the world, which can get data from a large variety of data sources and use it in Excel with Power Pivot or Power Query.
  • Report Builder to author printed paginated reports that can be share and published using the in SSRS Portal.
  • Power BI Desktop to author interactive visualizations with analytics capabilities.
  • Power BI Service, which is the portal that host Dashboards and Power BI reports.
  • We also can have Web Applications using Microsoft .NET MVC or Web Forms with Entity Framework that connect to any of these data sources.

On the bottom we have a variety of databases:

  • SQL Server Relational database, which could be an online transactional processing (OLTP) databases or Online analytical processing (OLAP) database, when use it as a data warehouse.
  • SQL Server Analysis Services (SSAS) Tabular Mode
  • SQL Server Analysis Services (SSAS) Multidimensional Mode
  • Power BI Imported Datasets, which are very similar to Tabular databases, but hosted on the cloud (Power BI Service) instead of on premise.

Traditionally, BI applications used to implement all rules regarding the data security within the application. For example we can have a BI App that implement security that allow users or group of users to access only to some specific set of data. The problem with this approach is it does not allow to reuse this security among other BI Tools. For example we can have security implemented in SSRS for folders and report level permissions or connections. Even though this SSRS security cannot be reused by Power BI nor Excel.

The best place to implement the security is right within the database, where the security can be centralized and maintained in only one place. On this way, any BI Tool or any App that uses the database, will also use the implemented security without the need to implement security in every single Web App or Tool.

The following picture shows a comparison of a database and application features. Business Intelligence and Security used to be common responsibilities of and application. Now databases have more powerful features in terms of business intelligence and security and these responsibilities can be implemented now in the database.

In order to implement a centralized and reusable security, we have to use these two security features available in all databases (Relational SQL, SSAS Tabular, SSAS Multidimensional):

  • Row Level Security (RLS) and
  • Active Directory (AD) Groups.

Implementing security in the database using RLS and AD give us the flexibility to use any BI tool that can connect to our database using an Active Directory account and our database will be protected using centralized security rules implemented right in the database.

In the following articles, I will implemented RLS and AD security across all these technologies and all BI tools. In these articles I will be share code samples, I’ll show How to unit test the security and also How to troubleshoot the security.

The following list is the series of articles to be publish related with this topic:

SQL Server 2016 On-Premise with Row-Level Security with Active Directory (Part I)

SQL Server 2016 On-Premise with Row-Level Security with Active Directory (Part II)

SSAS 2016 Tabular On Premise with Row-Level Security and Active Directory.

Client App Security (MVC, Web Forms, Web API) with SQL 2016 RLS and Active Directory

Power BI Security with Active Directory Synch and On-Premise Data Gateway.

Power BI using SSAS Tabular with Row Level Security.

Power BI using SSAS Multidimensional with Row Level Security.

Power BI – Imported Data with Row Level Security.

Power BI – Direct Query with Row Level Security.

Power BI: Integrate Power BI dashboard with a web application.