You may receive a "Permission denied" error message when an application role-based application tries to select records from any one of the system tables in a SQL Server 2005 master database

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Article ID: 906549 - View products that this article applies to.
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SYMPTOMS

If an application role-based application tries to select all records from any one of the system tables in a Microsoft SQL Server 2005 master database, you may experience one of the following symptoms:
  • No records are returned.
  • You receive the following error message:
    Permission denied.
For example, this problem may occur if the application uses the following query.
select * from master.dbo.syslogins

CAUSE

Application role-based applications are designed to work with specific information in a database. These applications cannot access system tables in a master view or in a dynamic management view. These views contain server-level information.

RESOLUTION

To resolve this problem, use certificate-signed procedures to access server-level system tables. Certificate-signed procedures offer the following benefits:
  • You do not have to use trace flags.
  • Less server-level information may be disclosed. Application role-based applications must use stored procedures instead of using general queries. Stored procedures are more likely to return only specific data that is required by the application.

WORKAROUND

To work around this problem, enable global trace flag 4616.

MORE INFORMATION

The following code sample is an example of a certificate-signed procedure.
USE master
GO

CREATE DATABASE approle_db ;
GO

CREATE LOGIN some_login WITH PASSWORD = 'SomePa$$word!' ;
GO

USE approle_db
GO

CREATE USER some_user FOR LOGIN some_login
GO

EXEC sp_addapprole 'an_approle', 'SomeAppRolePa$$word!' ;
GO

---------------------------------------------------------------------
-- This section shows how to use a certificate to authenticate
-- a signed procedure.
---------------------------------------------------------------------

CREATE LOGIN execute_as_login WITH PASSWORD = 'SomePa$$word!' ;
GO

USE master
GO

GRANT VIEW ANY DEFINITION TO execute_as_login ;
GRANT VIEW SERVER STATE   TO execute_as_login ;
GO

USE approle_db
GO

CREATE USER execute_as_user FOR LOGIN execute_as_login ;
GO

--
-- You must use EXECUTE AS 'authenticator' here because the application role
-- does not have a server identity. Therefore, the application role cannot use
-- the certificate permissions on the server.  Therefore, you
-- need a new execution context to which you can grant
-- the needed VIEW* permissions.
--
CREATE PROC access_server_system_tables
  WITH EXECUTE AS 'execute_as_user'
AS
  SELECT * FROM master.dbo.syslogins    ;
  SELECT * FROM master.dbo.sysprocesses ;
GO

GRANT EXECUTE ON access_server_system_tables TO an_approle ;
GO

CREATE CERTIFICATE signing_cert ENCRYPTION BY PASSWORD = 'SomeCertPa$$word'
    WITH SUBJECT  = 'Signing Cert' ;
GO

BACKUP CERTIFICATE signing_cert TO FILE = 'signing_cert.cer' ;
GO

ADD SIGNATURE TO access_server_system_tables
    BY CERTIFICATE signing_cert WITH PASSWORD = 'SomeCertPa$$word' ;
GO

---------------------------------------------------------------------
-- We must create a copy of the signing certificate in the target
-- database. In this case, the target database is the master database.
-- This copy of the signing certificate can vouch
-- for the execution contexts that enter this database from the
-- signed procedure.
---------------------------------------------------------------------
USE master
GO

CREATE CERTIFICATE signing_cert FROM FILE = 'signing_cert.cer' ;
GO

--
-- Because the VIEW* permissions in question are server-level permissions,
-- we need an AUTHENTICATE SERVER on a login-mapped certificate.
--
CREATE LOGIN signing_cert_login FROM CERTIFICATE signing_cert ;
GO

GRANT AUTHENTICATE SERVER TO signing_cert_login
GO


---------------------------------------------------------------------
-- Now you can open a new connection as "some_login" and
-- set the application role. Then, call the "access_server_system_tables"
-- procedure, and obtain verification that you can access server-level information
-- when the application role-based application runs.  




---------------------------------------------------------------------


---------------------------------------------------------------------
-- Clean up after the procedure.

---------------------------------------------------------------------
USE master
GO

DROP DATABASE approle_db ;
GO

DROP LOGIN some_login;
GO

DROP LOGIN execute_as_login;
GO

DROP LOGIN signing_cert_login ;
GO

DROP CERTIFICATE signing_cert;
GO

--
-- Make sure to delete the certificate file. For example, delete
-- C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\signing_cert.cer
--
EXEC sp_configure 'show advanced options', 1 ;
GO
RECONFIGURE ;
GO
EXEC sp_configure 'xp_cmdshell', 1 ;
GO
RECONFIGURE ;
GO

EXEC xp_cmdshell 'del "C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\signing_cert.cer"' ;
GO

EXEC sp_configure 'xp_cmdshell', 0 ;
GO
RECONFIGURE ;
GO


-- ============================================================================
-- - Application role access to server information - Demo usage.sql
--
--
--  This code is companion code that shows an example of application role access
--  to server information by using a certificate-signed procedure.
--
-- ============================================================================

--------------------------------------------------
-- Connect as some_login
--------------------------------------------------
USE approle_db
GO

EXEC sp_setapprole 'an_approle', 'SomeAppRolePa$$word!'
GO

EXEC access_server_system_tables
GO

Properties

Article ID: 906549 - Last Review: November 20, 2007 - Revision: 2.3
APPLIES TO
  • Microsoft SQL Server 2005 Developer Edition
  • Microsoft SQL Server 2005 Enterprise Edition
  • Microsoft SQL Server 2005 Enterprise Edition for Itanium-based Systems
  • Microsoft SQL Server 2005 Enterprise X64 Edition
  • Microsoft SQL Server 2005 Express Edition
  • Microsoft SQL Server 2005 Standard Edition
  • Microsoft SQL Server 2005 Standard Edition for Itanium-based Systems
  • Microsoft SQL Server 2005 Standard X64 Edition
  • Microsoft SQL Server 2005 Workgroup Edition
Keywords: 
kbsql2005engine kbtshoot kbprb KB906549

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