Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Linq/misc/SecurityUtils.cs

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+//------------------------------------------------------------------------------
+// <copyright file="SecurityUtils.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+/*
+ */
+
+
+#if WINFORMS_NAMESPACE
+    namespace System.Windows.Forms
+#elif DRAWING_NAMESPACE
+    namespace System.Drawing
+#elif WINFORMS_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 {
+
+#if FEATURE_MONO_CAS
+        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;
+            }
+        }
+#endif
+
+        private static void DemandReflectionAccess(Type type) {
+#if FEATURE_MONO_CAS
+            try {
+                MemberAccessPermission.Demand();
+            }
+            catch (SecurityException) {
+                DemandGrantSet(type.Assembly);
+            }
+#endif
+        }
+
+        [SecuritySafeCritical]
+        private static void DemandGrantSet(Assembly assembly) {
+#if FEATURE_MONO_CAS
+            PermissionSet targetGrantSet = assembly.PermissionSet;
+            targetGrantSet.AddPermission(RestrictedMemberAccessPermission);
+            targetGrantSet.Demand();
+#endif
+        }
+
+        private static bool HasReflectionPermission(Type type) {
+#if FEATURE_MONO_CAS
+            try {
+                DemandReflectionAccess(type);
+                return true;
+            }
+            catch (SecurityException) {
+            }
+
+            return false;
+#else
+            return true;
+#endif
+        }
+
+       
+        /// <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 (!WINFORMS_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
+    }
+}