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RegistryPermission Class

Controls the ability to access registry variables. This class cannot be inherited.

Namespace: System.Security.Permissions
Assembly: mscorlib (in mscorlib.dll)

'Declaration
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public NotInheritable Class RegistryPermission
	Inherits CodeAccessPermission
	Implements IUnrestrictedPermission
'Usage
Dim instance As RegistryPermission

/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class RegistryPermission extends CodeAccessPermission implements IUnrestrictedPermission
SerializableAttribute 
ComVisibleAttribute(true) 
public final class RegistryPermission extends CodeAccessPermission implements IUnrestrictedPermission
Not applicable.

RegistryPermission describes protected operations on registry variables. Registry variables should not be stored in memory locations where code without RegistryPermission can access them. If the registry object is passed to an untrusted caller it can be misused.

The allowed registry access types are defined by RegistryPermissionAccess. If more than one type of access is desired, they can be combined using the bitwise OR operation as shown in the code sample that follows.

Registry permission is defined in terms of canonical absolute paths; checks should always be made with canonical pathnames. Key access implies access to all values it contains and all variables under it.

Caution noteCaution:

RegistryPermission grants permission for all paths to a key, including both HKEY_CURRENT_USER and HKEY_USERS. To Deny access to a key, you must Deny all possible paths to the key. For example, to Deny access to HKEY_CURRENT_USER\Software\Microsoft\Cryptography, you must Deny HKEY_CURRENT_USER\Software\Microsoft\Cryptography, HKEY_USERS\.......\Software\Microsoft\Cryptography and any other path that you can use to access the key. A better technique to deal with multiple paths is to use a combination of PermitOnly and Deny. For more information on this subject and the use of PermitOnly with Deny, see "Canonicalization Problems Using Deny" in Using the Deny Method.

In the following code example, the RegistryPermissionf represents permission to read the values from the CentralProcessor key. Read and Write are RegistryPermissionAccess enumeration values.

Dim f As New RegistryPermission( _
RegistryPermissionAccess.Read, _
"HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0")

RegistryPermission f =  
    new RegistryPermission(RegistryPermissionAccess.Read,
        "HKEY_LOCAL_MACHINE\\HARDWARE\\DESCRIPTION\\"
        + "System\\CentralProcessor\\0");

The following code example adds permission to read from and write to the FloatingPointProcessor key to the RegistryPermissionf.

f.AddPathList( _
RegistryPermissionAccess.Write Or RegistryPermissionAccess.Read, _
"HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\FloatingPointProcessor\0")

f.AddPathList(RegistryPermissionAccess.Write |
    RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\\HARDWARE\\"
    + "DESCRIPTION\\System\\FloatingPointProcessor\\0");

The RegistryPermissionf now represents the permission to read from the CentralProcessor key and to read from and write to the FloatingPointProcessor key.

The following code example shows the behavior of the RegistryPermission class methods.

NoteNote:

The code example is intended to show the behavior of the methods, not to demonstrate their use. In general, the methods of permission classes are used by the security infrastructure; they are not typically used in applications. Generally, only the constructors are used in application code. The created instance validates or controls resource access by using inherited CodeAccessPermission methods such as Demand.

' This sample demonstrates the IsSubsetOf, Union, Intersect, Copy, ToXml, FromXml
' GetPathList, AddPathList, and SetPathList methods
' of the RegistryPermission class.

Imports System
Imports System.Security
Imports System.Security.Permissions
Imports System.Collections

Public Class RegistryPermissionDemo
    Private readPerm1 As New RegistryPermission(RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0")
    Private readPerm2 As New RegistryPermission(RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION")
    Private readPerm3 As New RegistryPermission(RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\FloatingPointProcessor\0")
    Private createPerm1 As New RegistryPermission(RegistryPermissionAccess.Create, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0")
    Private readPerm4 As IPermission

    ' IsSubsetOf determines whether the current permission is a subset of the specified permission.
    Private Function IsSubsetOfDemo() As Boolean

        Dim returnValue As Boolean = True

        If readPerm1.IsSubsetOf(readPerm2) Then

            Console.WriteLine(readPerm1.GetPathList(RegistryPermissionAccess.Read) + vbLf + " is a subset of " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + vbLf)
        Else
            Console.WriteLine(readPerm1.GetPathList(RegistryPermissionAccess.Read) + vbLf + " is not a subset of " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + vbLf)
        End If
        If createPerm1.IsSubsetOf(readPerm1) Then

            Console.WriteLine("RegistryPermissionAccess.Create" + vbLf + " is a subset of " + "RegistryPermissionAccess.Read" + vbLf)
        Else
            Console.WriteLine("RegistryPermissionAccess.Create" + vbLf + " is not a subset of " + "RegistryPermissionAccess.Read" + vbLf)
        End If

        Return returnValue

    End Function 'IsSubsetOfDemo

    ' Union creates a new permission that is the union of the current permission and
    ' the specified permission.
    Private Function UnionDemo() As Boolean

        Dim returnValue As Boolean = True
        readPerm3 = CType(readPerm1.Union(readPerm2), RegistryPermission)

        If readPerm3 Is Nothing Then
            Console.WriteLine("The union of " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.Read) + " " + vbLf + "and " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + " is null.")
        Else
            Console.WriteLine("The union of " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.Read) + " " + vbLf + "and " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + " = " + vbLf + vbTab + CType(readPerm3, RegistryPermission).GetPathList(RegistryPermissionAccess.Read).ToString())
        End If

        Return returnValue

    End Function 'UnionDemo

    ' Intersect creates and returns a new permission that is the intersection of the
    ' current permission and the permission specified.
    Private Function IntersectDemo() As Boolean

        Dim returnValue As Boolean = True

        readPerm3 = CType(readPerm1.Intersect(readPerm2), RegistryPermission)
        If Not (readPerm3 Is Nothing) AndAlso Not (readPerm3.GetPathList(RegistryPermissionAccess.Read) Is Nothing) Then

            Console.WriteLine("The intersection of " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.Read) + " " + vbLf + "and " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + " = " + vbLf + vbTab + CType(readPerm3, RegistryPermission).GetPathList(RegistryPermissionAccess.Read).ToString())
        Else
            Console.WriteLine("The intersection of " + vbLf + readPerm2.GetPathList(RegistryPermissionAccess.Read) + " " + vbLf + "and " + readPerm2.GetPathList(RegistryPermissionAccess.Read) + " is null. ")
        End If

        Return returnValue

    End Function 'IntersectDemo

    'Copy creates and returns an identical copy of the current permission.
    Private Function CopyDemo() As Boolean

        Dim returnValue As Boolean = True
        readPerm4 = CType(readPerm1.Copy(), RegistryPermission)
        If Not (readPerm4 Is Nothing) Then
            Console.WriteLine("Result of copy = " + readPerm4.ToXml().ToString() + vbLf)
        Else
            Console.WriteLine("Result of copy is null. " + vbLf)
        End If
        Return returnValue

    End Function 'CopyDemo

    ' ToXml creates an XML encoding of the permission and its current state; FromXml
    ' reconstructs a permission with the specified state from the XML encoding.
    Private Function ToFromXmlDemo() As Boolean

        Dim returnValue As Boolean = True
        readPerm2 = New RegistryPermission(PermissionState.None)
        readPerm2.FromXml(readPerm1.ToXml())
        Console.WriteLine("Result of ToFromXml = " + readPerm2.ToString() + vbLf)

        Return returnValue

    End Function 'ToFromXmlDemo

    ' AddPathList adds access for the specified registry variables to the existing state of the permission.
    ' SetPathList sets new access for the specified registry variable names to the existing state of the permission.
    ' GetPathList gets paths for all registry variables with the specified RegistryPermissionAccess.
    Private Function SetGetPathListDemo() As Boolean
        Try
            Console.WriteLine("********************************************************" + vbLf)

            Dim readPerm1 As RegistryPermission
            Console.WriteLine("Creating RegistryPermission with AllAccess rights for 'HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0'")
            readPerm1 = New RegistryPermission(RegistryPermissionAccess.AllAccess, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0")
            Console.WriteLine("Adding 'HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION' to the write access list, " + "and " + vbLf + " 'HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\FloatingPointProcessor\0' " + "to the read access list.")
            readPerm1.AddPathList(RegistryPermissionAccess.Write, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION")
            readPerm1.AddPathList(RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\FloatingPointProcessor\0")
            Console.WriteLine("Read access list before SetPathList = " + readPerm1.GetPathList(RegistryPermissionAccess.Read))
            Console.WriteLine("Setting read access rights to " + vbLf + "'HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0'")
            readPerm1.SetPathList(RegistryPermissionAccess.Read, "HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0")
            Console.WriteLine("Read access list after SetPathList = " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.Read))
            Console.WriteLine("Write access = " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.Write))
            Console.WriteLine("Write access Registry variables = " + vbLf + readPerm1.GetPathList(RegistryPermissionAccess.AllAccess))
        Catch e As ArgumentException
            ' RegistryPermissionAccess.AllAccess can not be used as a parameter for GetPathList.
            Console.WriteLine("An ArgumentException occured as a result of using AllAccess. " + _
            "AllAccess cannot be used as a parameter in GetPathList because it represents more than one " + _
            "type of registry variable access : " + vbLf + e.Message)
        End Try

        Return True

    End Function 'SetGetPathListDemo

    ' Invoke all demos.
    Public Function RunDemo() As Boolean

        Dim ret As Boolean = True
        Dim retTmp As Boolean
        ' Call IsSubset demo.
        If IsSubsetOfDemo() Then
            Console.Out.WriteLine("IsSubset demo completed successfully.")
        Else
            Console.Out.WriteLine("IsSubset demo failed.")
        End If
        ret = retTmp AndAlso ret

        ' Call the Union demo.
        retTmp = UnionDemo()
        If retTmp Then
            Console.Out.WriteLine("Union demo completed successfully.")
        Else
            Console.Out.WriteLine("Union demo failed.")
        End If
        ret = retTmp AndAlso ret

        ' Call the intersect demo.
        retTmp = UnionDemo()
        If retTmp Then
            Console.Out.WriteLine("Intersect demo completed successfully.")
        Else
            Console.Out.WriteLine("Intersect demo failed.")
        End If
        ret = retTmp AndAlso ret


        ' Call the Copy demo.
        retTmp = CopyDemo()
        If retTmp Then
            Console.Out.WriteLine("Copy demo completed successfully.")
        Else
            Console.Out.WriteLine("Copy demo failed.")
        End If
        ret = retTmp AndAlso ret

        ' Call the ToFromXml demo.
        retTmp = ToFromXmlDemo()
        If retTmp Then
            Console.Out.WriteLine("ToFromXml demo completed successfully.")
        Else
            Console.Out.WriteLine("ToFromXml demo failed.")
        End If
        ret = retTmp AndAlso ret

        ' Call the GetPathList demo.
        retTmp = SetGetPathListDemo()
        If retTmp Then
            Console.Out.WriteLine("SetGetPathList demo completed successfully.")
        Else
            Console.Out.WriteLine("SetGetPathList demo failed.")
        End If
        ret = retTmp AndAlso ret

        Return ret

    End Function 'RunDemo

    ' Test harness.
    Public Shared Sub Main(ByVal args() As String)
        Try
            Dim democase As New RegistryPermissionDemo()
            Dim ret As Boolean = democase.RunDemo()
            If ret Then
                Console.Out.WriteLine("The RegisterPermission demo completed successfully.")
                Console.Out.WriteLine("Press the Enter key to exit.")
                Dim consoleInput As String = Console.ReadLine()
                System.Environment.ExitCode = 100
            Else
                Console.Out.WriteLine("The RegisterPermission demo failed")
                Console.Out.WriteLine("Press the Enter key to exit.")
                Dim consoleInput As String = Console.ReadLine()
                System.Environment.ExitCode = 101
            End If
        Catch e As Exception
            Console.Out.WriteLine("The RegisterPermission demo failed")
            Console.WriteLine(e.ToString())
            Console.Out.WriteLine("Press the Enter key to exit.")
            Dim consoleInput As String = Console.ReadLine()
            System.Environment.ExitCode = 101
        End Try

    End Sub 'Main
End Class 'RegistryPermissionDemo


System.Object
   System.Security.CodeAccessPermission
    System.Security.Permissions.RegistryPermission

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0
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