RegistrySecurity.RemoveAccessRuleSpecific(RegistryAccessRule) Method

Definition

Namespace:

System.Security.AccessControl

Assembly:

Microsoft.Win32.Registry.dll

Searches for an access control rule that exactly matches the specified rule and, if found, removes it.

public:
 void RemoveAccessRuleSpecific(System::Security::AccessControl::RegistryAccessRule ^ rule);

public void RemoveAccessRuleSpecific (System.Security.AccessControl.RegistryAccessRule rule);

override this.RemoveAccessRuleSpecific : System.Security.AccessControl.RegistryAccessRule -> unit

Public Sub RemoveAccessRuleSpecific (rule As RegistryAccessRule)

Parameters

rule

RegistryAccessRule

The RegistryAccessRule to remove.

Exceptions

ArgumentNullException

rule is null.

Examples

The following code example shows that the RemoveAccessRuleSpecific method removes a rule only if it matches exactly.

The example creates two rules that allow different rights. The rules have compatible inheritance and propagation flags, so when the second rule is added it merges with the first. The example calls the RemoveAccessRuleSpecific method, specifying the first rule, but because the rules are merged there is no rule that matches. The example then calls the RemoveAccessRule method to the remove the second rule from the merged rule, and finally calls the RemoveAccessRuleSpecific method to remove the first rule.

Note

This example does not attach the security object to a RegistryKey object. See the RegistryKey.GetAccessControl method and the RegistryKey.SetAccessControl method.

using System;
using System.Security.AccessControl;
using System.Security.Principal;
using System.Security;
using Microsoft.Win32;

public class Example
{
    public static void Main()
    {
        string user = Environment.UserDomainName + "\\"
            + Environment.UserName;

        // Create a security object that grants no access.
        RegistrySecurity mSec = new RegistrySecurity();

        // Add a rule that grants the current user the right
        // to read and enumerate the name/value pairs in a key, 
        // to read its access and audit rules, to enumerate
        // its subkeys, to create subkeys, and to delete the key. 
        // The rule is inherited by all contained subkeys.
        //
        RegistryAccessRule rule1 = new RegistryAccessRule(user, 
            RegistryRights.ReadKey | RegistryRights.WriteKey
                | RegistryRights.Delete, 
            InheritanceFlags.ContainerInherit, 
            PropagationFlags.None, 
            AccessControlType.Allow);
        mSec.AddAccessRule(rule1);

        // Add a rule that allows the current user the right
        // right to take ownership of a key, using the same 
        // inheritance and propagation flags. This rule 
        // merges with the first rule.
        RegistryAccessRule rule2 = new RegistryAccessRule(user, 
            RegistryRights.ChangePermissions, 
            InheritanceFlags.ContainerInherit,
            PropagationFlags.None, 
            AccessControlType.Allow);
        mSec.AddAccessRule(rule2);

        // Display the rules in the security object.
        ShowSecurity(mSec);

        // Attempt to use RemoveRuleSpecific to remove the
        // first rule. The removal fails, because the rule
        // in the RegistrySecurity object has been altered.
        mSec.RemoveAccessRuleSpecific(rule1);

        // Show that the rule was not removed.
        ShowSecurity(mSec);

        // Use the RemoveAccessRule method to remove rule2,
        // and then use RemoveAccessRuleSpecific to remove
        // rule1.
        mSec.RemoveAccessRule(rule2);
        mSec.RemoveAccessRuleSpecific(rule1);

        // Show that the rules have been removed.
        ShowSecurity(mSec);
    }

    private static void ShowSecurity(RegistrySecurity security)
    {
        Console.WriteLine("\r\nCurrent access rules:\r\n");

        foreach( RegistryAccessRule ar in 
            security.GetAccessRules(true, true, typeof(NTAccount)) )
        {
            Console.WriteLine("        User: {0}", ar.IdentityReference);
            Console.WriteLine("        Type: {0}", ar.AccessControlType);
            Console.WriteLine("      Rights: {0}", ar.RegistryRights);
            Console.WriteLine(" Inheritance: {0}", ar.InheritanceFlags);
            Console.WriteLine(" Propagation: {0}", ar.PropagationFlags);
            Console.WriteLine("   Inherited? {0}", ar.IsInherited);
            Console.WriteLine();
        }
    }
}

/* This code example produces output similar to following:

Current access rules:

        User: TestDomain\TestUser
        Type: Allow
      Rights: SetValue, CreateSubKey, Delete, ReadKey, ChangePermissions
 Inheritance: ContainerInherit
 Propagation: None
   Inherited? False


Current access rules:

        User: TestDomain\TestUser
        Type: Allow
      Rights: SetValue, CreateSubKey, Delete, ReadKey, ChangePermissions
 Inheritance: ContainerInherit
 Propagation: None
   Inherited? False


Current access rules:

*/

Option Explicit
Imports System.Security.AccessControl
Imports System.Security.Principal
Imports System.Security
Imports Microsoft.Win32

Public Class Example

    Public Shared Sub Main()

        Dim user As String = Environment.UserDomainName _ 
            & "\" & Environment.UserName

        ' Create a security object that grants no access.
        Dim mSec As New RegistrySecurity()

        ' Add a rule that grants the current user the right
        ' to read and enumerate the name/value pairs in a key, 
        ' to read its access and audit rules, to enumerate
        ' its subkeys, to create subkeys, and to delete the key. 
        ' The rule is inherited by all contained subkeys.
        '
        Dim rule1 As New RegistryAccessRule(user, _
            RegistryRights.ReadKey Or RegistryRights.WriteKey _
                Or RegistryRights.Delete, _
            InheritanceFlags.ContainerInherit, _
            PropagationFlags.None, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule1)

        ' Add a rule that allows the current user the right
        ' right to take ownership of a key, using the same 
        ' inheritance and propagation flags. This rule 
        ' merges with the first rule.
        Dim rule2 As New RegistryAccessRule(user, _
            RegistryRights.ChangePermissions, _
            InheritanceFlags.ContainerInherit, _
            PropagationFlags.None, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule2)

        ' Display the rules in the security object.
        ShowSecurity(mSec)

        ' Attempt to use RemoveRuleSpecific to remove the
        ' first rule. The removal fails, because the rule
        ' in the RegistrySecurity object has been altered.
        mSec.RemoveAccessRuleSpecific(rule1)

        ' Show that the rule was not removed.
        ShowSecurity(mSec)

        ' Use the RemoveAccessRule method to remove rule2,
        ' and then use RemoveAccessRuleSpecific to remove
        ' rule1.
        mSec.RemoveAccessRule(rule2)
        mSec.RemoveAccessRuleSpecific(rule1)

        ' Show that the rules have been removed.
        ShowSecurity(mSec)

    End Sub 

    Private Shared Sub ShowSecurity(ByVal security As RegistrySecurity)
        Console.WriteLine(vbCrLf & "Current access rules:" & vbCrLf)

        For Each ar As RegistryAccessRule In _
            security.GetAccessRules(True, True, GetType(NTAccount))

            Console.WriteLine("        User: {0}", ar.IdentityReference)
            Console.WriteLine("        Type: {0}", ar.AccessControlType)
            Console.WriteLine("      Rights: {0}", ar.RegistryRights)
            Console.WriteLine(" Inheritance: {0}", ar.InheritanceFlags)
            Console.WriteLine(" Propagation: {0}", ar.PropagationFlags)
            Console.WriteLine("   Inherited? {0}", ar.IsInherited)
            Console.WriteLine()
        Next

    End Sub
End Class 

'This code example produces output similar to following:
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: SetValue, CreateSubKey, Delete, ReadKey, ChangePermissions
' Inheritance: ContainerInherit
' Propagation: None
'   Inherited? False
'
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: SetValue, CreateSubKey, Delete, ReadKey, ChangePermissions
' Inheritance: ContainerInherit
' Propagation: None
'   Inherited? False
'
'
'Current access rules:
'

Remarks

The rule is removed only if it exactly matches rule in all details, including flags. Other rules with the same user and AccessControlType are not affected.

Important

A rule represents one or more underlying access control entries (ACE), and these entries are split or combined as necessary when you modify the access security rules for a user. Thus, a rule might no longer exist in the specific form it had when it was added, and in that case the RemoveAccessRuleSpecific method cannot remove it.