Customizing the Medium Trust Policy

Article
07/14/2010

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The latest Enterprise Library information can be found at the Enterprise Library site.

The tables in the following sections show the additional permissions—beyond those granted by default in the medium trust policy—that may be required by your application. You need to grant these additional permissions only if you want to use these specific features. Unless otherwise noted, make these modifications in the custom policy file.

For extended examples of how to modify a custom policy file, see How To: Use Medium Trust in ASP.NET 2.0 on MSDN. If you are using a partial-trust policy other than medium trust, other restrictions and permissions may apply. For a table that lists the different permissions and the trust policies that allow them, see ASP.NET Code Access Security on MSDN.

These additional permissions are the following:

General Permissions
Caching Application Block Permissions
Data Access Application Block Permissions
Exception Handling Application Block Permissions
Cryptography Application Block Permissions
Security Application Block Permissions
Logging Application Block Permissions
Validation Application Block Permissions
Policy Injection Application Block Permissions

General Permissions

Table 1 lists the additional permissions that may be required by core features of the Enterprise Library.

Table 1: Additional General Permissions

Feature	Subfeature	Permissions
Configuration	Not applicable	Add the ConfigurationPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Unrestricted to read the relevant sections in the policy file. Alternatively, add requirePermission = false to the relevant sections in the configuration file.
Configuration	File configuration source	Add the FileIOPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Read and PathDiscovery attributes to the configuration file's folder and to the Machine.config file.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write.
Instrumentation	Event log	Add the EventLogPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Administer for the local computer.
Instrumentation	Windows Management Instrumentation (WMI)	WMI is not supported under partial trust.

Caching Application Block

Table 2 lists the additional permissions that may be required by the Caching Application Block.

Table 2: Additional Permissions for the Caching Application Block

Feature	Subfeature	Permissions
Storage	Database	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the SerializationFormatter flag to the Flags attribute.
Storage	IsolatedStorage	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the SerializationFormatter flag to the Flags attribute.
Encryption	SymmetricStorage EncryptionProvider (from the Cryptography Application Block)	Add the DataProtectionPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the ProtectData and UnprotectData flags to the Flags attribute.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write on the Enterprise Library Caching Counters category.

Data Access Application Block

Table 3 lists the additional permissions that may be required by the Data Access Application Block.

Table 3: Additional Permissions for the Data Access Application Block

Feature	Subfeature	Permissions
Oracle database	Not applicable	Add the OraclePermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Unrestricted attribute to true.
Odbc database	Not applicable	Add the OdbcPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Unrestricted attribute to true.
OleDb database	Not applicable	Add the OleDbPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Unrestricted attribute to true.
SqlCe database	Not applicable	SQL Server Compact Edition is not supported under partial trust.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write on the Enterprise Library Data Counters category.

Exception Handling Application Block

Table 4 lists the additional permissions that may be required by the Exception Handling Application Block.

Table 4: Additional Permissions for the Exception Handling Application Block

Feature	Subfeature	Permissions
General	Context information	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the UnmanagedCode flag to the Flags attribute.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write on the Enterprise Library Exception Handling Counters category.

Cryptography Application Block

Table 5 lists the additional permissions that may be required by the Cryptography Application Block.

Table 5: Additional Permissions for the Exception Handling Application Block

Feature	Subfeature	Permissions
General	Not applicable	Add the DataProtectionPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the ProtectData and UnprotectData flags to the Flags attribute.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write on the Enterprise Library Cryptography Counters category.

Security Application Block

Table 6 lists the additional permissions that may be required by the Security Application Block.

Table 6: Additional Permissions for the Security Application Block

Feature	Subfeature	Permissions
General	Not applicable	If the application uses IIdentity and IPrincipal objects instead of GenericIdentity and GenericPrincipal, it may require additional permissions. For example, the WindowsIdentity object requires that you include the SecurityPermission class in the <SecurityClasses> element and that, within the <IPermission> element, you add the UnmanagedCode and ControlPrincipal flags to the Flags attribute.
Authorization	AzMan (Authorization Manager)	AzMan is not supported under partial trust. For more information, see Known Issues.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Write on the Enterprise Library Security Counters category.

Logging Application Block

Table 7 lists the additional permissions that may be required by the Logging Application Block.

Table 7: Additional Permissions for the Logging Application Block

Feature	Subfeature	Permissions
General	Context information	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the UnmanagedCode flag to the Flags attribute.
Tracing	Not applicable	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the UnmanagedCode flag to the Flags attribute.
Trace listeners	General	If you want to use the TraceOptions.Callstack method, add the EnvironmentPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Unrestricted. If you want to use the TraceOptions.ProcessID method, add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the UnmanagedCode flag to the Flags attribute.
Trace listeners	Event Log	Add the EventLogPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Access attribute to Administer to the local computer.
Trace listeners	Message queuing	Message queuing is not supported under partial trust.
Trace listeners	Flat File and Rolling Flat File	Add the FileIOPermission class to the <SecurityClasses> element. Within the <IPermission> element, set the Read and Write attributes to the destination file's folder. Set the PathDiscovery and Append attributes to the file. (The file can inherit the permissions from its folder).
Trace listeners	WMI	WMI is not supported under partial trust.
Trace listeners	Database	Add the appropriate database permission for the target database. (See Table 3 for the Data Access Application Block.)
Formatters	BinaryFormatter class	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the SerializationFormatter flag to the Flags attribute.
Formatters	TextFormatter class	There are no permissions to add, although some tokens may not be available if they refer to properties that are not available under partial trust.
General	ContextItems class	Add the SecurityPermission class to the <SecurityClasses> element. Within the <IPermission> element, add the Infrastructure flag to the Flags attribute.
Instrumentation	Performance counters	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Set the Access attribute to Write on the Enterprise Library Logging Counters category.

Validation Application Block

Table 8 lists the additional permissions that may be required by the Validation Application Block.

Table 8: Additional Permissions for the Validation Application Block

Feature	Subfeature	Permissions
Core	Not applicable	No special permissions required over those required for general and medium trust (LocalIntranet).
WinForms	Not applicable	No special permissions required over those required for general and medium trust (LocalIntranet).
Instrumentation	Not applicable	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Set the Access attribute to Write on the Enterprise Library Logging Counters category.

Policy Injection Application Block

Table 9 lists the additional permissions that may be required by the Policy Injection Application Block.

Table 9: Additional Permissions for the Policy Injection Application Block

Feature	Subfeature	Permissions
Core	Not applicable	No special permissions required over those required for general and medium trust (LocalIntranet).
WinForms	Not applicable	No special permissions required over those required for general and medium trust (LocalIntranet).
Instrumentation	Not applicable	Add the PerformanceCounterPermission class to the <SecurityClasses> element. Set the Access attribute to Write on the Enterprise Library Logging Counters category.
CallHandlers	PerformanceCountersInstaller	Requires full trust.
CallHandlers	Other handlers	Uses the same requirements as the handler.

Limitations on Using Partial Trust

There may be some limitations regarding how you use partial trust with an Enterprise Library application block. These limitations include the following:

The Enterprise Library throws a SecurityException if it cannot obtain the mandatory permissions.
Some calls to Logging Application Block trace listener classes fail.
ASP.NET application directories require specific permissions.
The AzMan provider is not available with partial trust.

Enterprise Library Throws Security Exception

If your application cannot obtain the necessary permissions to use a particular Enterprise Library feature, the Enterprise Library typically throws a SecurityException back to the application. The only time this does not happen is when the code that requires the permissions is not seen as critical to the feature's operation. For example, if the Logging Application Block is unable to call the API that provides information about the current process, this information is simply left out of the logged message and the call succeeds.

Limitations on Logging Application Block Trace Listeners

Creating an event log and creating a directory for a disk file both require full trust. Therefore, the Logging Application Block listeners fail when they attempt these actions while running under partial trust. The following two of the classes in the Logging Application Block cause a load failure even if you do not use them in your code because the Enterprise Library initializes and caches them:

FormattedEventLogTraceListener. This class creates an instance of an EventLog object in its constructor. This call fails under partial trust, which prevents the application block from creating a LogWriter object if the trace listener is configured in the application configuration file. This occurs even if you do not use the FormattedEventLogTraceListener class in your application.
FormattedTextWriterTraceListener. This class checks whether the specified directory exists in its constructor and creates the directory if it does not exist. However, the Directory.Exists method that it uses returns false under partial trust if the FileIOPermission class with the appropriate permissions for the target directory have not been added to the custom policy file. This prevents the application block from creating a LogWriter object if the trace listener is configured in the application configuration file. This occurs even if you do not use the FormattedTextWriterTraceListener class in your application.

For all other listeners that are configured in the application configuration file, including the TextWriterTraceListener class, the code fails only when the code calls the TraceData method to access a listener.

ASP.NET Application Directories Require Permissions

By default, ASP.NET runs under the ASPNET account in Windows 2000 and Windows XP; it runs under the NetworkService account in Windows Server 2003. If you specify a FileConfigurationSource object that is located in a directory outside the ASP.NET application folders, the account under which the application is running must have the correct permissions. The following procedure describes how to set these permissions.

To set permissions for ASP.NET Application Directories

Add the FileIOPermission class to the policy file's <SecurityClasses> element.
Set the Read and PathDiscovery attributes to the file specified in the Enterprise Library FileConfigurationSource class.
Set the Read and Execute ACL permissions to the file specified in the FileConfigurationSource class.

AzMan Provider Not Available

The AzMan provider requires the Enterprise Library to be fully trusted. Because Enterprise Library does not support partially trusted calls to trusted assemblies, any application that uses the AzMan provider in the Enterprise Library must also be fully trusted. You cannot use the AzMan provider with a partial-trust security level.

Retired Content
This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This page may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.
The latest Enterprise Library information can be found at the Enterprise Library site.