.NET: 通过AppDomain级别控制安全策略的例子

来源：互联网发布：react.js中文网编辑：程序博客网时间：2024/06/05 08:11

这是在课堂上讲的一个小范例。场景是：

1. 我们有一个主程序，它公开了一套API，允许其他开发人员为它设计插件

2. 因为插件不是我们设计的，所以我们需要确保这些插件不会恶意地伤害到用意。为此，我们希望将插件的运行权限降低。

解决方案就是，我们单独用一个AppDomain来运行这些插件，并且在该AppDomain级别单独设置安全策略。

1. API

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace API{    public interface IPlugin    {        void Run();    }}

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2. Plugin

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace PluginSample{    public class Plug:API.IPlugin    {        #region IPlugin 成员        void API.IPlugin.Run()        {            MainForm form = new MainForm();            form.ShowDialog();        }        #endregion    }}

Plugin中有一个窗体，里面有一个按钮，执行访问注册表的操作

using System;using System.Windows.Forms;using Microsoft.Win32;namespace PluginSample{    public partial class MainForm : Form    {        public MainForm()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {            RegistryKey key = Registry.CurrentUser.CreateSubKey("Plugins");            key.SetValue("Version", "1.0.0");            key.SetValue("Update", DateTime.Now.ToString());            MessageBox.Show("操作已经完成");        }    }}

3. 宿主程序

为了实现跨应用程序域的加载，我们设计了一个AssemblyLoader类型

using System;using System.Linq;using System.Reflection;namespace Host_WinForms{    [Serializable]    class AssemblyLoader:MarshalByRefObject        //必须继承MarshalByRefObject，否则无法实现AppDomain级别的安全控制    {        public string[] GetPluginTypeNames(string path) {            Assembly ass = Assembly.LoadFile(path);            var query = from type in ass.GetTypes()                        where type.GetInterface(typeof(API.IPlugin).FullName) != null                        select type.FullName;            return query.ToArray();        }        public void RunPlugin(string path, string typeName) {            Assembly ass = Assembly.LoadFile(path);            API.IPlugin plugin = (API.IPlugin)ass.CreateInstance(typeName);            plugin.Run();        }    }}

宿主程序有一个MainForm

using System;using System.Windows.Forms;using System.IO;using System.Security.Permissions;using System.Security.Policy;using System.Security;namespace Host_WinForms{    public partial class MainForm : Form    {        public MainForm()        {            InitializeComponent();        }        private void Log(string message)        {            richTextBox1.AppendText(DateTime.Now.ToString().PadRight(25));            richTextBox1.AppendText(message);            richTextBox1.AppendText(Environment.NewLine);        }        private void MainForm_Load(object sender, EventArgs e)        {            Log("主程序启动");            Log("主程序域中的程序集:");            foreach (var item in AppDomain.CurrentDomain.GetAssemblies())            {                Log(item.FullName);            }            //加载所有的插件（遍历当前目录下面的dll),动态创建菜单项目            AppDomain plugindomain = AppDomain.CreateDomain("PluginDomain");            AssemblyLoader loader = (AssemblyLoader)plugindomain.CreateInstanceFromAndUnwrap("Host_WinForms.exe", typeof(AssemblyLoader).FullName);            foreach (var item in Directory.GetFiles(Environment.CurrentDirectory, "*.dll"))            {                foreach (var type in loader.GetPluginTypeNames(item))                {                    ToolStripMenuItem menuitem = new ToolStripMenuItem(type);                    menuitem.Tag = item;                    menuitem.Click += (o1, e1) =>                    {                        //当点击了之后执行有关的插件                        AppDomain plugindomaintemp = AppDomain.CreateDomain("PluginDomain");                        PolicyLevel level = PolicyLevel.CreateAppDomainLevel();                        PermissionSet ps = level.GetNamedPermissionSet("Internet");                        ps.AddPermission(new FileIOPermission(                            FileIOPermissionAccess.AllAccess, Environment.CurrentDirectory));                        level.RootCodeGroup.PolicyStatement = new PolicyStatement(ps);                        plugindomaintemp.SetAppDomainPolicy(level);                        try                        {                            AssemblyLoader loadertemp = (AssemblyLoader)plugindomaintemp.CreateInstanceFromAndUnwrap(                                "Host_WinForms.exe", typeof(AssemblyLoader).FullName);                            ToolStripMenuItem temp = (ToolStripMenuItem)o1;                            loadertemp.RunPlugin(temp.Tag.ToString(), temp.Text);                        }                        catch (Exception ex) {                            MessageBox.Show(string.Format("运行插件发生如下错误:{0}", ex.Message));                        }                        finally                        {                            AppDomain.Unload(plugindomaintemp);                        }                    };                    AllPluginMenu.DropDownItems.Add(menuitem);                }            }            AppDomain.Unload(plugindomain);            Log("主程序域中的程序集:");            foreach (var item in AppDomain.CurrentDomain.GetAssemblies())            {                Log(item.FullName);            }        }    }}

4. 运行效果