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<legacyImpersonationPolicy> Element 

Specifies that the Windows identity does not flow across asynchronous points, regardless of the flow settings for the execution context on the current thread.


<legacyImpersonationPolicy  
   enabled="true|false"/>

The following sections describe attributes, child elements, and parent elements.

Attributes

Attribute Description

enabled

Required attribute.

Specifies that the WindowsIdentity does not flow across asynchronous points, regardless of the ExecutionContext flow settings on the current thread.

Enabled Attribute

Value Description

false

WindowsIdentity flows across asynchronous points depending upon the ExecutionContext flow settings for the current thread. This is the default.

true

WindowsIdentity does not flow across asynchronous points, regardless of the ExecutionContext flow settings on the current thread.

Child Elements

None.

Parent Elements

Element Description

configuration

The root element in every configuration file used by the common language runtime and .NET Framework applications.

runtime

Contains information about assembly binding and garbage collection.

In the .NET Framework versions 1.0 and 1.1, the WindowsIdentity does not flow across any user-defined asynchronous points. In the .NET Framework version 2.0, there is an ExecutionContext object that contains information about the currently executing thread, and flows it across asynchronous points within an application domain. The WindowsIdentity also flows as part of the information that flows across the asynchronous points, which means that if an impersonation context exits it will flow as well. This element is used to specify that the WindowsIdentity does not flow across asynchronous points.

NoteNote

The common language runtime (CLR) is aware of impersonation operations performed using only managed code, not of impersonation performed outside of managed code, such as through platform invoke to unmanaged code or through direct calls to Win32 functions. Only managed WindowsIdentity objects can flow across asynchronous points, unless the alwaysFlowImpersonationPolicy element has been set to true (<alwaysFlowImpersonationPolicy enabled="true"/>). Setting the alwaysFlowImpersonationPolicy element to true specifies that the Windows identity always flows across asynchronous points, regardless of how impersonation was performed. For more information on flowing unmanaged impersonation across asynchronous points, see <alwaysFlowImpersonationPolicy> Element.

This element can be used only in the application configuration file.

You can alter this default behavior in two other ways:

  1. In managed code on a per-thread basis.

    You can suppress the flow on a per-thread basis by modifying the ExecutionContext and SecurityContext settings by using the System.Threading.ExecutionContext.SuppressFlow, System.Security.SecurityContext.SuppressFlowWindowsIdentity or System.Security.SecurityContext.SuppressFlow method.

  2. In the call to the unmanaged hosting interface to load the common language runtime (CLR).

    If an unmanaged hosting interface (instead of a simple managed executable) is used to load the CLR, you can specify a special flag in the call to the CorBindToRuntimeEx function. To enable the compatibility mode for the entire process, set the flags parameter for CorBindToRuntimeEx to STARTUP_LEGACY_IMPERSONATION.

The following example shows how to specify the legacy behavior that does not flow the Windows identity across asynchronous points.

<configuration>
   <runtime>
      <legacyImpersonationPolicy enabled="true"/>
   </runtime>
</configuration>
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