System.Security.Permissions.UIPermission Class

Summary

Controls the permissions related to user interfaces and the clipboard. This class cannot be inherited.

C# Syntax:

[Serializable] public sealed class UIPermission : CodeAccessPermission, IUnrestrictedPermission

Drawing and user input events in windows are user interfaces.

The permission to use windows can be one of the following: unrestricted, limited to safe top-level windows, only safe subwindows, or no window drawing or user input event access allowed. Safe windows are restricted in title and size to prevent possible spoofing by potentially harmful code.

The permission to use the clipboard can be one of the following: unrestricted, write-only, or no clipboard access allowed. The paste limitation prevents potentially harmful applications from taking data from the clipboard without the user's consent, while still allowing the Cut, Copy, and Paste operations when initiated by the user through keyboard commands.

System.Security.Permissions Namespace See also:
MSDN: permissions | MSDN: requestingpermissions | UIPermissionAttribute | UIPermissionWindow | UIPermissionClipboard

System.Security.Permissions.UIPermission Member List:

Public Constructors

ctor #1	Overloaded: .ctor(PermissionState state) Initializes a new instance of the UIPermission class with either fully restricted or unrestricted access, as specified.
ctor #2	Overloaded: .ctor(UIPermissionClipboard clipboardFlag) Initializes a new instance of the UIPermission class with the permissions for the clipboard, and no access to windows.
ctor #3	Overloaded: .ctor(UIPermissionWindow windowFlag) Initializes a new instance of the UIPermission class with the permissions for windows, and no access to the clipboard.
ctor #4	Overloaded: .ctor(UIPermissionWindow windowFlag, UIPermissionClipboard clipboardFlag) Initializes a new instance of the UIPermission class with the specified permissions for windows and the clipboard.

Public Properties

Clipboard	Read-write Gets or sets the clipboard access represented by the permission.
Window	Read-write Gets or sets the window access represented by the permission.

Public Methods

Assert (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Assert Asserts that calling code can access the resource identified by the current permission through the code that calls this method, even if callers higher in the stack have not been granted permission to access the resource.
Copy	Overridden: Creates and returns an identical copy of the current permission.
Demand (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Demand Forces a SecurityException at run time if all callers higher in the call stack have not been granted the permission specified by the current instance.
Deny (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.Deny Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
FromXml	Overridden: Reconstructs a permission with a specified state from an XML encoding.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
Intersect	Overridden: Creates and returns a permission that is the intersection of the current permission and the specified permission.
IsSubsetOf	Overridden: Determines whether the current permission is a subset of the specified permission.
IsUnrestricted	Returns a value indicating whether the current permission is unrestricted.
PermitOnly (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.PermitOnly Prevents callers higher in the call stack from using the code that calls this method to access all resources except for the resource specified by the current instance.
ToString (inherited from System.Security.CodeAccessPermission)	See base class member description: System.Security.CodeAccessPermission.ToString Creates and returns a string representation of the current permission object.
ToXml	Overridden: Creates an XML encoding of the permission and its current state.
Union	Overridden: Creates a permission that is the union of the permission and the specified permission.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

• System.Object
• System.Security.CodeAccessPermission
• System.Security.Permissions.UIPermission

System.Security.Permissions.UIPermission Member Details

Summary

Initializes a new instance of the UIPermission class with either fully restricted or unrestricted access, as specified.

C# Syntax:

public UIPermission(    PermissionState state );

state

One of the PermissionState values. One of the PermissionState values.

Exceptions

Exception Type	Condition
ArgumentException	The state parameter is not a valid PermissionState.

This constructor creates either the fully restricted (None) or the Unrestricted form of the permission.

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Summary

Initializes a new instance of the UIPermission class with the permissions for the clipboard, and no access to windows.

C# Syntax:

public UIPermission(UIPermission(    UIPermissionClipboard clipboardFlag );

clipboardFlag

One of the UIPermissionClipboard values. One of the UIPermissionClipboard values.

Exceptions

Exception Type	Condition
ArgumentException	The clipboardFlag parameter is not a valid UIPermissionClipboard value.

To set both the clipboard and window permissions, use the constructor that takes parameters for both.

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Summary

Initializes a new instance of the UIPermission class with the permissions for windows, and no access to the clipboard.

C# Syntax:

public UIPermission(UIPermission(    UIPermissionWindow windowFlag );

windowFlag

One of the UIPermissionWindow values. One of the UIPermissionWindow values.

Exceptions

Exception Type	Condition
ArgumentException	The windowFlag parameter is not a valid UIPermissionWindow value.

To set both the clipboard and window permissions, use the constructor that takes parameters for both.

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Summary

Initializes a new instance of the UIPermission class with the specified permissions for windows and the clipboard.

C# Syntax:

public UIPermission(UIPermissionWindow windowFlag, UIPermission(    UIPermissionWindow windowFlag,    UIPermissionClipboard clipboardFlag );

windowFlag

One of the UIPermissionWindow values. One of the UIPermissionWindow values.

clipboardFlag

One of the UIPermissionClipboard values. One of the UIPermissionClipboard values.

Exceptions

Exception Type	Condition
ArgumentException	The windowFlag parameter is not a valid UIPermissionWindow value. -or- The clipboardFlag parameter is not a valid UIPermissionClipboard value.

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Summary

Gets or sets the clipboard access represented by the permission.

C# Syntax:

public UIPermissionClipboard Clipboard {get; set;}

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Summary

Gets or sets the window access represented by the permission.

C# Syntax:

public UIPermissionWindow Window {get; set;}

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Inherited
See base class member description: System.Security.CodeAccessPermission.Assert

Summary

Asserts that calling code can access the resource identified by the current permission through the code that calls this method, even if callers higher in the stack have not been granted permission to access the resource.

C# Syntax:

public void Assert();

Exceptions

Exception Type	Condition
SecurityException	The calling code does not have SecurityPermissionFlag.Assertion. -or- There is already an active CodeAccessPermission.Assert for the current frame.

Implements:

IStackWalk.Assert

The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack. Calling CodeAccessPermission.Assert prevents a stack walk originating lower in the call stack from proceeding up the call stack beyond the code that calls this method. Therefore, even if callers higher on the call stack do not have the requisite permissions to access a resource, they can still access it through the code that calls this method on the necessary permission. An assertion is effective only if the code that calls CodeAccessPermission.Assert passes the security check for the permission that it is asserting.

The call to CodeAccessPermission.Assert is effective until the calling code returns to its caller. Only one CodeAccessPermission.Assert can be active on a frame. An attempt to call CodeAccessPermission.Assert when an active CodeAccessPermission.Assert exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertAssert or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.Assert.

CodeAccessPermission.Assert is ignored for a permission not granted because a demand for that permission will not succeed. However, if code lower on the call stack calls CodeAccessPermission.Demand for that permission, a SecurityException is thrown when the stack walk reaches the code that tried to call CodeAccessPermission.Assert. This happens because the code that called CodeAccessPermission.Assert has not been granted the permission, even though it tried to CodeAccessPermission.Assert it.

Because calling CodeAccessPermission.Assert removes the requirement that all code in the call chain must be granted permission to access the specified resource, it can open up security vulnerabilities if used incorrectly or inappropriately. Therefore, it should be used with great caution.

Notes to inheritors: You cannot override this method.

SecurityPermission for the ability to call CodeAccessPermission.Assert. Associated enumeration: SecurityPermissionFlag.Assertion

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Summary

Creates and returns an identical copy of the current permission.

C# Syntax:

public override IPermission Copy();

Return Value:

A copy of the current permission.

Implements:

IPermission.Copy

A copy of the permission represents the same access to resources as the original permission.

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Inherited
See base class member description: System.Security.CodeAccessPermission.Demand

Summary

Forces a SecurityException at run time if all callers higher in the call stack have not been granted the permission specified by the current instance.

C# Syntax:

public void Demand();

Exceptions

Exception Type	Condition
SecurityException	A caller higher in the call stack does not have the permission specified by the current instance. -or- A caller higher in the call stack has called CodeAccessPermission.Deny on the current permission object.

Implements:

IPermission.Demand

Implements:

IStackWalk.Demand

This method is typically used by secure libraries to ensure that callers have permission to access a resource. For example, a file class in a secure class library calls CodeAccessPermission.Demand for the necessary FileIOPermission before performing a file operation requested by the caller.

The permissions of the code that calls this method are not examined; the check begins from the immediate caller of that code and proceeds up the stack. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack. CodeAccessPermission.Demand succeeds only if no SecurityException is raised.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Security.CodeAccessPermission.Deny

Summary

Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.

C# Syntax:

public void Deny();

Exceptions

Exception Type	Condition
SecurityException	There is already an active CodeAccessPermission.Deny for the current frame.

Implements:

IStackWalk.Deny

This method prevents callers higher in the call stack from accessing the protected resource through the code that calls this method, even if those callers have been granted permission to access it. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

CodeAccessPermission.Deny can limit the liability of the programmer or prevent accidental security vulnerabilities because it prevents the method that calls CodeAccessPermission.Deny from being used to access the resource protected by the denied permission. If a method calls CodeAccessPermission.Deny on a permission, and if a CodeAccessPermission.Demand for that permission is invoked by a caller lower in the call stack, that security check will fail when it reaches the CodeAccessPermission.Deny.

The call to CodeAccessPermission.Deny is effective until the calling code returns to its caller. Only one CodeAccessPermission.Deny can be active on a frame. An attempt to call CodeAccessPermission.Deny when an active CodeAccessPermission.Deny exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertDeny or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.Deny. CodeAccessPermission.Deny is ignored for a permission not granted because a demand for that permission will not succeed.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~UIPermission();

For more information on members inherited from System.Object click on the link above.

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Summary

Reconstructs a permission with a specified state from an XML encoding.

C# Syntax:

public override void FromXml(    SecurityElement esd );

esd

The XML encoding used to reconstruct the permission.

Exceptions

Exception Type	Condition
ArgumentNullException	The esd parameter is null.
ArgumentException	The esd parameter is not a valid permission element. -or- The esd parameter's version number is not valid.

Implements:

ISecurityEncodable.FromXml

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Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Summary

Creates and returns a permission that is the intersection of the current permission and the specified permission.

C# Syntax:

public override IPermission Intersect(    IPermission target );

target

A permission to intersect with the current permission. It must be the same type as the current permission.

Return Value:

A new permission that represents the intersection of the current permission and the specified permission. This new permission is null if the intersection is empty.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.Intersect

The intersection of two permissions is a permission that describes the set of operations they both describe in common. Specifically, it represents the least permissive values of UIPermissionWindow and UIPermissionClipboard from those in the current permission and the specified permission.

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Summary

Determines whether the current permission is a subset of the specified permission.

C# Syntax:

public override bool IsSubsetOf(    IPermission target );

target

A permission to test for the subset relationship. This permission must be the same type as the current permission.

Return Value:

true if the current permission is a subset of the specified permission; otherwise, false.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.IsSubsetOf

The current permission is a subset of the specified permission if all demands that succeed for the current permission also succeed for the specified permission. That is, the specified permission contains at least the permissions contained in the subset. For UIPermission.IsSubsetOf to return true, both the UIPermissionWindow and UIPermissionClipboard values of the current permission must be equal to or less permissive than the values of the specified permission.

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Summary

Returns a value indicating whether the current permission is unrestricted.

C# Syntax:

public bool IsUnrestricted();

Return Value:

true if the current permission is unrestricted; otherwise, false.

Implements:

IUnrestrictedPermission.IsUnrestricted

An unrestricted permission represents access to any and all resources protected by the permission.

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Security.CodeAccessPermission.PermitOnly

Summary

Prevents callers higher in the call stack from using the code that calls this method to access all resources except for the resource specified by the current instance.

C# Syntax:

public void PermitOnly();

Exceptions

Exception Type	Condition
SecurityException	There is already an active CodeAccessPermission.PermitOnly for the current frame.

Implements:

IStackWalk.PermitOnly

CodeAccessPermission.PermitOnly is similar to CodeAccessPermission.Deny, in that both cause stack walks to fail when they would otherwise succeed. The difference is that CodeAccessPermission.Deny specifies permissions that will cause the stack walk to fail, but CodeAccessPermission.PermitOnly specifies the only permissions that do not cause the stack walk to fail.

Call this method to ensure that your code can be used to access only the specified resources. The call to CodeAccessPermission.PermitOnly is effective until the calling code returns to its caller. Only one CodeAccessPermission.PermitOnly can be active on a frame. An attempt to call CodeAccessPermission.PermitOnly when an active CodeAccessPermission.PermitOnly exists on the frame results in a SecurityException. Call CodeAccessPermission.RevertPermitOnly or CodeAccessPermission.RevertAll to remove an active CodeAccessPermission.PermitOnly.

CodeAccessPermission.PermitOnly is ignored for a permission not granted because a demand for that permission will not succeed. However, if code lower on the call stack later calls CodeAccessPermission.Demand for that permission, a SecurityException is thrown when the stack walk reaches the code that tried to call CodeAccessPermission.PermitOnly. This is because the code that called CodeAccessPermission.PermitOnly has not been granted the permission, even though it called CodeAccessPermission.PermitOnly for that permission. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

Notes to inheritors: You cannot override this method.

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Inherited
See base class member description: System.Security.CodeAccessPermission.ToString

Summary

Creates and returns a string representation of the current permission object.

C# Syntax:

public override string ToString();

Return Value:

A string representation of the current permission object.

This method is useful in debugging when you need to display the permission as a string.

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Summary

Creates an XML encoding of the permission and its current state.

C# Syntax:

public override SecurityElement ToXml();

Return Value:

An XML encoding of the permission, including any state information.

Implements:

ISecurityEncodable.ToXml

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Summary

Creates a permission that is the union of the permission and the specified permission.

C# Syntax:

public override IPermission Union(    IPermission target );

target

A permission to combine with the current permission. It must be the same type as the current permission.

Return Value:

A new permission that represents the union of the current permission and the specified permission.

Exceptions

Exception Type	Condition
ArgumentException	The target parameter is not null and is not of the same type as the current permission.

Implements:

IPermission.Union

The result of a call to UIPermission.Union is a permission that represents all the operations represented by the current permission as well as all the operations represented by the specified permission. Specifically, it represents the most permissive values of UIPermissionWindow and UIPermissionClipboard from those in the current permission and the specified permission.

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