MutexAccessRule Class

Definition

public ref class MutexAccessRule sealed : System::Security::AccessControl::AccessRule

public sealed class MutexAccessRule : System.Security.AccessControl.AccessRule

[System.Security.SecurityCritical]
public sealed class MutexAccessRule : System.Security.AccessControl.AccessRule

type MutexAccessRule = class
    inherit AccessRule

[<System.Security.SecurityCritical>]
type MutexAccessRule = class
    inherit AccessRule

Public NotInheritable Class MutexAccessRule
Inherits AccessRule

Inheritance

Object

AuthorizationRule

AccessRule

MutexAccessRule

Attributes

SecurityCriticalAttribute

Examples

The following code example demonstrates the creation and use of MutexAccessRule objects. The example creates a MutexSecurity object, adds rules that allow and deny various rights for the current user, and displays the resulting pair of rules. The example then allows new rights for the current user and displays the result, showing that the new rights are merged with the existing Allow rule.

using System;
using System.Threading;
using System.Security.AccessControl;
using System.Security.Principal;

public class Example
{
    public static void Main()
    {
        // Create a string representing the current user.
        string user = Environment.UserDomainName + "\\" + 
            Environment.UserName;

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

        // Add a rule that grants the current user the 
        // right to enter or release the mutex.
        MutexAccessRule rule = new MutexAccessRule(user, 
            MutexRights.Synchronize | MutexRights.Modify, 
            AccessControlType.Allow);
        mSec.AddAccessRule(rule);

        // Add a rule that denies the current user the 
        // right to change permissions on the mutex.
        rule = new MutexAccessRule(user, 
            MutexRights.ChangePermissions, 
            AccessControlType.Deny);
        mSec.AddAccessRule(rule);

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

        // Add a rule that allows the current user the 
        // right to read permissions on the mutex. This rule
        // is merged with the existing Allow rule.
        rule = new MutexAccessRule(user, 
            MutexRights.ReadPermissions, 
            AccessControlType.Allow);
        mSec.AddAccessRule(rule);

        ShowSecurity(mSec);
    }

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

        foreach(MutexAccessRule 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.MutexRights);
            Console.WriteLine();
        }
    }
}

/*This code example produces output similar to following:

Current access rules:

        User: TestDomain\TestUser
        Type: Deny
      Rights: ChangePermissions

        User: TestDomain\TestUser
        Type: Allow
      Rights: Modify, Synchronize


Current access rules:

        User: TestDomain\TestUser
        Type: Deny
      Rights: ChangePermissions

        User: TestDomain\TestUser
        Type: Allow
      Rights: Modify, ReadPermissions, Synchronize
 */

Imports System.Threading
Imports System.Security.AccessControl
Imports System.Security.Principal

Public Class Example

    Public Shared Sub Main()

        ' Create a string representing the current user.
        Dim user As String = Environment.UserDomainName _ 
            & "\" & Environment.UserName

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

        ' Add a rule that grants the current user the 
        ' right to enter or release the mutex.
        Dim rule As New MutexAccessRule(user, _
            MutexRights.Synchronize _
            Or MutexRights.Modify, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule)

        ' Add a rule that denies the current user the 
        ' right to change permissions on the mutex.
        rule = New MutexAccessRule(user, _
            MutexRights.ChangePermissions, _
            AccessControlType.Deny)
        mSec.AddAccessRule(rule)

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

        ' Add a rule that allows the current user the 
        ' right to read permissions on the mutex. This rule
        ' is merged with the existing Allow rule.
        rule = New MutexAccessRule(user, _
            MutexRights.ReadPermissions, _
            AccessControlType.Allow)
        mSec.AddAccessRule(rule)

        ShowSecurity(mSec)

    End Sub 

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

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

            Console.WriteLine("        User: {0}", ar.IdentityReference)
            Console.WriteLine("        Type: {0}", ar.AccessControlType)
            Console.WriteLine("      Rights: {0}", ar.MutexRights)
            Console.WriteLine()
        Next

    End Sub
End Class 

'This code example produces output similar to following:
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Deny
'      Rights: ChangePermissions
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: Modify, Synchronize
'
'
'Current access rules:
'
'        User: TestDomain\TestUser
'        Type: Deny
'      Rights: ChangePermissions
'
'        User: TestDomain\TestUser
'        Type: Allow
'      Rights: Modify, ReadPermissions, Synchronize

Remarks

The MutexAccessRule class is one of a set of classes that the .NET Framework provides for managing Windows access control security on named system mutexes. For an overview of these classes, and their relationship to the underlying Windows access control structures, see MutexSecurity.

To get a list of the rules currently applied to a named mutex, use the Mutex.GetAccessControl method to get a MutexSecurity object, and then use its GetAccessRules method to obtain a collection of MutexAccessRule objects.

MutexAccessRule objects do not map one-to-one with access control entries in the underlying discretionary access control list (DACL). When you get the set of all access rules for a mutex, the set contains the minimum number of rules currently required to express all the access control entries.

Use MutexAccessRule objects to specify access rights to allow or deny to a user or group. A MutexAccessRule object always represents either allowed access or denied access, never both.

To apply a rule to a named system mutex, use the Mutex.GetAccessControl method to get the MutexSecurity object. Modify the MutexSecurity object by using its methods to add the rule, and then use the Mutex.SetAccessControl method to reattach the security object.

MutexAccessRule objects are immutable. Security for a mutex is modified using the methods of the MutexSecurity class to add or remove rules; as you do this, the underlying access control entries are modified.

Constructors

Properties

Methods

Applies to

See also

• MutexSecurity