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//------------------------------------------------------------------------------
// <copyright file="SecurityUtils.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
/*
*/
#if Microsoft_NAMESPACE
namespace System.Windows.Forms
#elif DRAWING_NAMESPACE
namespace System.Drawing
#elif Microsoft_PUBLIC_GRAPHICS_LIBRARY
namespace System.Internal
#elif SYSTEM_NAMESPACE
namespace System
#elif SYSTEM_WEB
namespace System.Web
#elif SYSTEM_DATA_LINQ
namespace System.Data.Linq
#else
namespace System.Windows.Forms
#endif
{
using System;
using System.Reflection;
using System.Diagnostics.CodeAnalysis;
using System.Security;
using System.Security.Permissions;
/// <devdoc>
/// Useful methods to securely call 'dangerous' managed APIs (especially reflection).
/// See http://wiki/default.aspx/Microsoft.Projects.DotNetClient.SecurityConcernsAroundReflection
/// for more information specifically about why we need to be careful about reflection invocations.
/// </devdoc>
internal static class SecurityUtils {
private static volatile ReflectionPermission memberAccessPermission = null;
private static volatile ReflectionPermission restrictedMemberAccessPermission = null;
private static ReflectionPermission MemberAccessPermission
{
get {
if (memberAccessPermission == null) {
memberAccessPermission = new ReflectionPermission(ReflectionPermissionFlag.MemberAccess);
}
return memberAccessPermission;
}
}
private static ReflectionPermission RestrictedMemberAccessPermission {
get {
if (restrictedMemberAccessPermission == null) {
restrictedMemberAccessPermission = new ReflectionPermission(ReflectionPermissionFlag.RestrictedMemberAccess);
}
return restrictedMemberAccessPermission;
}
}
private static void DemandReflectionAccess(Type type) {
try {
MemberAccessPermission.Demand();
}
catch (SecurityException) {
DemandGrantSet(type.Assembly);
}
}
[SecuritySafeCritical]
private static void DemandGrantSet(Assembly assembly) {
PermissionSet targetGrantSet = assembly.PermissionSet;
targetGrantSet.AddPermission(RestrictedMemberAccessPermission);
targetGrantSet.Demand();
}
private static bool HasReflectionPermission(Type type) {
try {
DemandReflectionAccess(type);
return true;
}
catch (SecurityException) {
}
return false;
}
/// <devdoc>
/// This helper method provides safe access to Activator.CreateInstance.
/// NOTE: This overload will work only with public .ctors.
/// </devdoc>
internal static object SecureCreateInstance(Type type) {
return SecureCreateInstance(type, null, false);
}
/// <devdoc>
/// This helper method provides safe access to Activator.CreateInstance.
/// Set allowNonPublic to true if you want non public ctors to be used.
/// </devdoc>
internal static object SecureCreateInstance(Type type, object[] args, bool allowNonPublic) {
if (type == null) {
throw new ArgumentNullException("type");
}
BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.CreateInstance;
// if it's an internal type, we demand reflection permission.
if (!type.IsVisible) {
DemandReflectionAccess(type);
}
else if (allowNonPublic && !HasReflectionPermission(type)) {
// Someone is trying to instantiate a public type in *our* assembly, but does not
// have full reflection permission. We shouldn't pass BindingFlags.NonPublic in this case.
// The reason we don't directly demand the permission here is because we don't know whether
// a public or non-public .ctor will be invoked. We want to allow the public .ctor case to
// succeed.
allowNonPublic = false;
}
if (allowNonPublic) {
flags |= BindingFlags.NonPublic;
}
return Activator.CreateInstance(type, flags, null, args, null);
}
#if (!Microsoft_NAMESPACE)
/// <devdoc>
/// This helper method provides safe access to Activator.CreateInstance.
/// NOTE: This overload will work only with public .ctors.
/// </devdoc>
internal static object SecureCreateInstance(Type type, object[] args) {
return SecureCreateInstance(type, args, false);
}
/// <devdoc>
/// Helper method to safely invoke a .ctor. You should prefer SecureCreateInstance to this.
/// Set allowNonPublic to true if you want non public ctors to be used.
/// </devdoc>
internal static object SecureConstructorInvoke(Type type, Type[] argTypes, object[] args, bool allowNonPublic) {
return SecureConstructorInvoke(type, argTypes, args, allowNonPublic, BindingFlags.Default);
}
/// <devdoc>
/// Helper method to safely invoke a .ctor. You should prefer SecureCreateInstance to this.
/// Set allowNonPublic to true if you want non public ctors to be used.
/// The 'extraFlags' parameter is used to pass in any other flags you need,
/// besides Public, NonPublic and Instance.
/// </devdoc>
internal static object SecureConstructorInvoke(Type type, Type[] argTypes, object[] args,
bool allowNonPublic, BindingFlags extraFlags) {
if (type == null) {
throw new ArgumentNullException("type");
}
// if it's an internal type, we demand reflection permission.
if (!type.IsVisible) {
DemandReflectionAccess(type);
}
else if (allowNonPublic && !HasReflectionPermission(type)) {
// Someone is trying to invoke a ctor on a public type, but does not
// have full reflection permission. We shouldn't pass BindingFlags.NonPublic in this case.
allowNonPublic = false;
}
BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | extraFlags;
if (!allowNonPublic) {
flags &= ~BindingFlags.NonPublic;
}
ConstructorInfo ctor = type.GetConstructor(flags, null, argTypes, null);
if (ctor != null) {
return ctor.Invoke(args);
}
return null;
}
private static bool GenericArgumentsAreVisible(MethodInfo method) {
if (method.IsGenericMethod) {
Type[] parameterTypes = method.GetGenericArguments();
foreach (Type type in parameterTypes) {
if (!type.IsVisible) {
return false;
}
}
}
return true;
}
/// <devdoc>
/// This helper method provides safe access to FieldInfo's GetValue method.
/// </devdoc>
internal static object FieldInfoGetValue(FieldInfo field, object target) {
Type type = field.DeclaringType;
if (type == null) {
// Type is null for Global fields.
if (!field.IsPublic) {
DemandGrantSet(field.Module.Assembly);
}
} else if (!(type != null && type.IsVisible && field.IsPublic)) {
DemandReflectionAccess(type);
}
return field.GetValue(target);
}
/// <devdoc>
/// This helper method provides safe access to MethodInfo's Invoke method.
/// </devdoc>
internal static object MethodInfoInvoke(MethodInfo method, object target, object[] args) {
Type type = method.DeclaringType;
if (type == null) {
// Type is null for Global methods. In this case we would need to demand grant set on
// the containing assembly for internal methods.
if (!(method.IsPublic && GenericArgumentsAreVisible(method))) {
DemandGrantSet(method.Module.Assembly);
}
} else if (!(type.IsVisible && method.IsPublic && GenericArgumentsAreVisible(method))) {
// this demand is required for internal types in system.dll and its friend assemblies.
DemandReflectionAccess(type);
}
return method.Invoke(target, args);
}
/// <devdoc>
/// This helper method provides safe access to ConstructorInfo's Invoke method.
/// Constructors can't be generic, so we don't check if argument types are visible
/// </devdoc>
internal static object ConstructorInfoInvoke(ConstructorInfo ctor, object[] args) {
Type type = ctor.DeclaringType;
if ((type != null) && !(type.IsVisible && ctor.IsPublic)) {
DemandReflectionAccess(type);
}
return ctor.Invoke(args);
}
/// <devdoc>
/// This helper method provides safe access to Array.CreateInstance.
/// </devdoc>
internal static object ArrayCreateInstance(Type type, int length) {
if (!type.IsVisible) {
DemandReflectionAccess(type);
}
return Array.CreateInstance(type, length);
}
#endif
}
}
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