FirstMatchCodeGroup Class

Definition

Namespace:

System.Security.Policy

Assembly:

System.Security.Permissions.dll

Source:

FirstMatchCodeGroup.cs

Caution

This type is obsolete. See https://go.microsoft.com/fwlink/?LinkID=155570 for more information.

Allows security policy to be defined by the union of the policy statement of a code group and that of the first child code group that matches. This class cannot be inherited.

C#

[System.Obsolete("This type is obsolete. See https://go.microsoft.com/fwlink/?LinkID=155570 for more information.")]
public sealed class FirstMatchCodeGroup : System.Security.Policy.CodeGroup

Inheritance

Object

CodeGroup

FirstMatchCodeGroup

Attributes

ObsoleteAttribute

Examples

The following example shows the use of members of the FirstMatchCodeGroup class.

C#

using System;
using System.Security;
using System.Security.Policy;
using System.Security.Permissions;
using System.Reflection;

class Members
{
    [STAThread]
    static void Main(string[] args)
    {
        // Create a new FirstMatchCodeGroup.
        FirstMatchCodeGroup codeGroup = constructDefaultGroup();

        // Create a deep copy of the FirstMatchCodeGroup.
        FirstMatchCodeGroup copyCodeGroup = 
            (FirstMatchCodeGroup)codeGroup.Copy();
        // Compare the original code group with the copy.
        CompareTwoCodeGroups(codeGroup, copyCodeGroup);

        addPolicy(ref codeGroup);
        addXmlMember(ref codeGroup);
        updateMembershipCondition(ref codeGroup);
        addChildCodeGroup(ref codeGroup);

        Console.Write("Comparing the resolved code group ");
        Console.WriteLine("with the initial code group.");
        FirstMatchCodeGroup resolvedCodeGroup =
            ResolveGroupToEvidence(codeGroup);
        if (CompareTwoCodeGroups(codeGroup, resolvedCodeGroup))
        {
            PrintCodeGroup(resolvedCodeGroup);
        }
        else
        {
            PrintCodeGroup(codeGroup);
        }
        
        Console.WriteLine("This sample completed successfully; " +
            "press Enter to exit.");
        Console.ReadLine();
    }

    // Create a FirstMatchCodeGroup with an exclusive policy and membership
    // condition.
    private static FirstMatchCodeGroup constructDefaultGroup()
    {
        // Construct a new FirstMatchCodeGroup with Read, Write, Append
        // and PathDiscovery access.
        // Create read access permission to the root directory on drive C.
        FileIOPermission rootFilePermissions =
            new FileIOPermission(PermissionState.None);
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read;
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read,"C:\\");

        // Add a permission to a named permission set.
        NamedPermissionSet namedPermissions =
            new NamedPermissionSet("RootPermissions");
        namedPermissions.AddPermission(rootFilePermissions);

        // Create a PolicyStatement with exclusive rights to the policy.
        PolicyStatement policy = new PolicyStatement(
            namedPermissions,PolicyStatementAttribute.Exclusive);

        // Create a FirstMatchCodeGroup with a membership condition that
        // matches all code, and an exclusive policy.
        FirstMatchCodeGroup codeGroup =
            new FirstMatchCodeGroup(
            new AllMembershipCondition(),
            policy);

        // Set the name of the first match code group.
        codeGroup.Name = "TempCodeGroup";

        // Set the description of the first match code group.
        codeGroup.Description = "Temp folder permissions group";

        return codeGroup;
    }

    // Add file permission to restrict write access to all files 
    // on the local machine.
    private static void addPolicy(ref FirstMatchCodeGroup codeGroup)
    {
        // Set the PolicyStatement property to a policy with read access to
        // the root directory on drive C.
        FileIOPermission rootFilePermissions =
            new FileIOPermission(PermissionState.None);
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read;
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read,"C:\\");

        NamedPermissionSet namedPermissions =
            new NamedPermissionSet("RootPermissions");
        namedPermissions.AddPermission(rootFilePermissions);

        // Create a PolicyStatement with exclusive rights to the policy.
        PolicyStatement policy = new PolicyStatement(
            namedPermissions,
            PolicyStatementAttribute.Exclusive);

        codeGroup.PolicyStatement = policy;
    }

    // Set the membership condition of the code group.
    private static void updateMembershipCondition(
        ref FirstMatchCodeGroup codeGroup)
    {
        // Set the membership condition of the specified FirstMatchCodeGroup
        // to the Intranet zone.
        ZoneMembershipCondition zoneCondition =
            new ZoneMembershipCondition(SecurityZone.Intranet);
        codeGroup.MembershipCondition = zoneCondition;
    }

    // Create a child code group with read-access file permissions and add it
    // to the specified code group.
    private static void addChildCodeGroup(ref FirstMatchCodeGroup codeGroup)
    {
        // Create a first match code group with read access.
        FileIOPermission rootFilePermissions = 
            new FileIOPermission(PermissionState.None);
        rootFilePermissions.AllLocalFiles = FileIOPermissionAccess.Read;
        rootFilePermissions.SetPathList(FileIOPermissionAccess.Read,"C:\\");

        PermissionSet permissions =
            new PermissionSet(PermissionState.Unrestricted);
        permissions.AddPermission(rootFilePermissions);

        FirstMatchCodeGroup tempFolderCodeGroup = new FirstMatchCodeGroup(
            new AllMembershipCondition(), 
            new PolicyStatement(permissions));

        // Set the name of the child code group and add it to 
        // the specified code group.
        tempFolderCodeGroup.Name = "Read-only code group";
        codeGroup.AddChild(tempFolderCodeGroup);
    }

    // Compare the two FirstMatchCodeGroups.
    private static bool CompareTwoCodeGroups(
        FirstMatchCodeGroup firstCodeGroup, 
        FirstMatchCodeGroup secondCodeGroup)
    {
        // Compare the two specified FirstMatchCodeGroups for equality.
        if (firstCodeGroup.Equals(secondCodeGroup))
        {
            Console.WriteLine("The two code groups are equal.");
            return true;
        }
        else 
        {
            Console.WriteLine("The two code groups are not equal.");
            return false;
        }
    }

    // Retrieve the resolved policy based on executing evidence found 
    // in the specified code group.
    private static string ResolveEvidence(CodeGroup codeGroup)
    {
        string policyString = "None";

        // Resolve the policy based on the executing assembly's evidence.
        Assembly assembly = typeof(Members).Assembly;
        Evidence executingEvidence = assembly.Evidence;

        PolicyStatement policy = codeGroup.Resolve(executingEvidence);

        if (policy != null)
        {
            policyString = policy.ToString();
        }

        return policyString;
    }

    // Retrieve the resolved code group based on the evidence from the 
    // specified code group.
    private static FirstMatchCodeGroup ResolveGroupToEvidence(
        FirstMatchCodeGroup codeGroup)
    {
        // Resolve matching code groups to the executing assembly.
        Assembly assembly = typeof(Members).Assembly;
        Evidence evidence = assembly.Evidence;
        CodeGroup resolvedCodeGroup = 
            codeGroup.ResolveMatchingCodeGroups(evidence);

        return (FirstMatchCodeGroup)resolvedCodeGroup;
    }

    // If a domain attribute is not found in the specified 
    // FirstMatchCodeGroup, add a child XML element identifying a custom
    // membership condition.
    private static void addXmlMember(ref FirstMatchCodeGroup codeGroup)
    {
        SecurityElement xmlElement = codeGroup.ToXml();

        SecurityElement rootElement = new SecurityElement("CodeGroup");

        if (xmlElement.Attribute("domain") == null) 
        {
            SecurityElement newElement = 
                new SecurityElement("CustomMembershipCondition");
            newElement.AddAttribute("class","CustomMembershipCondition");
            newElement.AddAttribute("version","1");
            newElement.AddAttribute("domain","contoso.com");

            rootElement.AddChild(newElement);

            codeGroup.FromXml(rootElement);
        }

        Console.WriteLine("Added a custom membership condition:");
        Console.WriteLine(rootElement.ToString());
    }

    // Print the properties of the specified code group to the console.
    private static void PrintCodeGroup(CodeGroup codeGroup)
    {
        // Compare the type of the specified object with the
        // FirstMatchCodeGroup type.
        if (!codeGroup.GetType().Equals(typeof(FirstMatchCodeGroup)))
        {
            throw new ArgumentException(
                "Expected the FirstMatchCodeGroup type.");
        }
        
        string codeGroupName = codeGroup.Name;
        string membershipCondition = codeGroup.MembershipCondition.ToString();
        string permissionSetName = codeGroup.PermissionSetName;

        int hashCode = codeGroup.GetHashCode();

        string mergeLogic = "";
        if (codeGroup.MergeLogic.Equals("First Match"))
        {
            mergeLogic = "with first-match merge logic";
        }

        // Retrieve the class path for the FirstMatchCodeGroup.
        string firstMatchGroupClass = codeGroup.ToString();

        string attributeString = "";
        // Retrieve the string representation of the FirstMatchCodeGroup's
        // attributes.
        if (codeGroup.AttributeString != null)
        {
            attributeString = codeGroup.AttributeString;
        }

        // Write a summary to the console window.
        Console.WriteLine("\n*** " + firstMatchGroupClass + " summary ***");
        Console.Write("A FirstMatchCodeGroup named ");
        Console.Write(codeGroupName + mergeLogic);
        Console.Write(" has been created with hash code(" + hashCode + ").");
        Console.Write("\nThis code group contains a " + membershipCondition);
        Console.Write(" membership condition with the ");
        Console.WriteLine(permissionSetName + " permission set.");

        Console.Write("The code group contains the following policy: ");
        Console.Write(ResolveEvidence(codeGroup));
        Console.Write("\nIt also contains the following attributes: ");
        Console.WriteLine(attributeString);

        int childCount = codeGroup.Children.Count;
        if (childCount > 0 )
        {
            Console.Write("There are " + childCount);
            Console.WriteLine(" child elements in the code group.");

            // Iterate through the child code groups to display their names
            // and then remove them from the specified code group.
            for (int i=0; i < childCount; i++)
            {
                // Retrieve a child code group, which has been cast as a
                // FirstMatchCodeGroup type.
                FirstMatchCodeGroup childCodeGroup = 
                    (FirstMatchCodeGroup)codeGroup.Children[i];

                Console.Write("Removing the " + childCodeGroup.Name + ".");
                // Remove the child code group.
                codeGroup.RemoveChild(childCodeGroup);
            }

            Console.WriteLine();
        }
        else
        {
            Console.WriteLine(" No child code groups were found in this" + 
                " code group.");
        }
    }
}
//
// This sample produces the following output:
//
// The two code groups are equal.
// Added a custom membership condition:
//   <CustomMembershipCondition class="CustomMembershipCondition"
//                              version="1"
//                              domain="contoso.com"/>
//
// Comparing the resolved code group with the initial code group.
// The two code groups are not equal.
//
// *** System.Security.Policy.FirstMatchCodeGroup summary ***
// A FirstMatchCodeGroup named with first-match merge logic has been created
// with hash code(113151525).
// This code group contains a Zone - Intranet membership condition with the 
// permission set. The code group contains the following policy: 
// It also contains the following attributes:
// There are 1 child elements in the code group.
// Removing the Read-only code group.
// This sample completed successfully; press Enter to exit.

Remarks

Caution

Code Access Security (CAS) has been deprecated across all versions of .NET Framework and .NET. Recent versions of .NET do not honor CAS annotations and produce errors if CAS-related APIs are used. Developers should seek alternative means of accomplishing security tasks.

Code groups are the building blocks of code access security policy. Each policy level consists of a root code group that can have child code groups. Each child code group can have their own child code groups; this behavior extends to any number of levels, forming a tree. Each code group has a membership condition that determines if a given assembly belongs to it based on the evidence for that assembly. Only code groups whose membership conditions match a given assembly and their child code groups apply policy.

Like any code group, FirstMatchCodeGroup only applies when its membership condition matches evidence for an assembly. If there is a match, it tests the membership condition of each child in order, stopping when the first match occurs. The result of FirstMatchCodeGroup is the union of the policy statement of the root code group and the policy statement of the first child group of that code group that matches.

FirstMatchCodeGroup is intended for programmatic use by application domain hosts to set domain policy.

Constructors

FirstMatchCodeGroup(IMembershipCondition, PolicyStatement)

Initializes a new instance of the FirstMatchCodeGroup class.

Properties

AttributeString	Gets a string representation of the attributes of the policy statement for the code group. (Inherited from CodeGroup)
Children	Gets or sets an ordered list of the child code groups of a code group. (Inherited from CodeGroup)
Description	Gets or sets the description of the code group. (Inherited from CodeGroup)
MembershipCondition	Gets or sets the code group's membership condition. (Inherited from CodeGroup)
MergeLogic	Gets the merge logic.
Name	Gets or sets the name of the code group. (Inherited from CodeGroup)
PermissionSetName	Gets the name of the named permission set for the code group. (Inherited from CodeGroup)
PolicyStatement	Gets or sets the policy statement associated with the code group. (Inherited from CodeGroup)

Methods

AddChild(CodeGroup)	Adds a child code group to the current code group. (Inherited from CodeGroup)
Copy()	Makes a deep copy of the code group.
CreateXml(SecurityElement, PolicyLevel)	When overridden in a derived class, serializes properties and internal state specific to a derived code group and adds the serialization to the specified SecurityElement. (Inherited from CodeGroup)
Equals(CodeGroup, Boolean)	Determines whether the specified code group is equivalent to the current code group, checking the child code groups as well, if specified. (Inherited from CodeGroup)
Equals(Object)	Determines whether the specified code group is equivalent to the current code group. (Inherited from CodeGroup)
FromXml(SecurityElement, PolicyLevel)	Reconstructs a security object with a given state and policy level from an XML encoding. (Inherited from CodeGroup)
FromXml(SecurityElement)	Reconstructs a security object with a given state from an XML encoding. (Inherited from CodeGroup)
GetHashCode()	Gets the hash code of the current code group. (Inherited from CodeGroup)
ParseXml(SecurityElement, PolicyLevel)	When overridden in a derived class, reconstructs properties and internal state specific to a derived code group from the specified SecurityElement. (Inherited from CodeGroup)
RemoveChild(CodeGroup)	Removes the specified child code group. (Inherited from CodeGroup)
Resolve(Evidence)	Resolves policy for the code group and its descendants for a set of evidence.
ResolveMatchingCodeGroups(Evidence)	Resolves matching code groups.
ToXml()	Creates an XML encoding of the security object and its current state. (Inherited from CodeGroup)
ToXml(PolicyLevel)	Creates an XML encoding of the security object, its current state, and the policy level within which the code exists. (Inherited from CodeGroup)

Applies to