无法复制文件，即使在 C# 中授予了 FileIOPermission

我正在尝试FileIOPermission在 Windows 7 中的 .NET 3.5 中。我是 Windows XP 用户，并且因为我是管理员而被授予此权限

我写了下面的代码，测试一下是否可以写入C:\Program Files\Outlook……

static void Main(string[] args)
{
    Console.WriteLine("Am I an administrator? " + new WindowsPrincipal(WindowsIdentity.GetCurrent()).IsInRole(WindowsBuiltInRole.Administrator);

    //  Try and open a file in C:\Program Files\Microsoft Office\Office14\BCSLaunch.dll
    string path = @"C:\Program Files\Microsoft Office\Office14\BCSLaunch.dll";

    try
    {
        FileIOPermission ioPerm = new FileIOPermission(FileIOPermissionAccess.Read, path);
        ioPerm.Demand();

        string backupPath = Path.ChangeExtension(path, ".bak");
        FileIOPermission writeAccess = new FileIOPermission(FileIOPermissionAccess.AllAccess, backupPath);
        writeAccess.Demand();

        Console.WriteLine("Read access is permitted: {0} => {1}",path,SecurityManager.IsGranted(ioPerm));
        Console.WriteLine("Write backup file is permitted: {0} => {1}", backupPath, SecurityManager.IsGranted(writeAccess));

        File.Copy(path, backupPath);

        Console.WriteLine("File copied! {0}",backupPath);
        Console.WriteLine("Deleting file.....");
        File.Delete(path);
    }
    catch (UnauthorizedAccessException uae)
    {
        Console.WriteLine(uae.ToString());
    }

    Console.ReadLine();
}

所以该程序会导致UnauthorizedAccessException（这是我所期望的），但我不明白的是Demand()允许许可，SecurityManager确认已授予许可，但在执行时File.Copy()我确实得到了例外。

虽然我很高兴看到 .NET 阻止了我，但为什么我打电话时它没有提前通知我Demand()?

我得到以下输出：

Am I an administrator? False
Read access is permitted: C:\Program Files\Microsoft Office\Office14\BCSLaunch.dll => True
Write backup file is permitted: C:\Program Files\Microsoft Office\Office14\BCSLaunch.bak => True
System.UnauthorizedAccessException: Access to the path 'C:\Program Files\Microsoft Office\Office14\BCSLaunch.bak' is denied.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite)
   at System.IO.File.Copy(String sourceFileName, String destFileName)
   at TryAndGetUACPrompt.Program.Main(String[] args) in C:\Users\..............
  

请有人帮助我理解为什么我收到的信息相互矛盾？

--

更新 - 19:30 GMT

我使用以下代码查看了源文件的 ACL：

Console.WriteLine("ACL Permissions for Source....");
FileSecurity fileSecurityForOriginalPath = new FileSecurity(path, AccessControlSections.Access);

foreach (FileSystemAccessRule rule in fileSecurityForOriginalPath.GetAccessRules(true,true,typeof(NTAccount)))
{
   Console.WriteLine("{0} => {1}", rule.FileSystemRights, rule.AccessControlType);
}

输出如下：

ACL Permissions for Source....
FullControl => Allow
FullControl => Allow
ReadAndExecute, Synchronize => Allow
  

因此，我确实有机会阅读它。但是，我尝试使用此代码来查看备份路径的权限，显然，我收到一个异常，因为我的备份（目标）文件实际上并不存在，因此我无法检查权限在上面。

接下来我将尝试另一个建议，将此检查移至另一种方法中。

更新 - 19:45 GMT

我已将读/写要求重构为另一种方法：

private static FileIOPermission CheckWriteAccess(string backupPath)
{
    FileIOPermission writeAccess = new FileIOPermission(FileIOPermissionAccess.AllAccess, backupPath);
    writeAccess.Demand();
    return writeAccess;
}

private static FileIOPermission CheckReadAccess(string path)
{
    FileIOPermission ioPerm = new FileIOPermission(FileIOPermissionAccess.Read, path);
    ioPerm.Demand();
    return ioPerm;
}

这些都无一例外地返回正常。

因此，如果 .NET 安全性增强了 DACL，我想知道为什么它认为它会成功，如果实际上并非如此。

--

格林尼治标准时间 19:57 更新

好的，我检查了目录的权限，而不是 backupFile （目标文件），并将其作为输出（使用 .GetAccessRules() 中的 AuthorizationRuleCollection 上的 foreach ）

Checking write access in this directory....
FullControl => Allow
268435456 => Allow
FullControl => Allow
268435456 => Allow
FullControl => Allow
268435456 => Allow
ReadAndExecute, Synchronize => Allow
-1610612736 => Allow
268435456 => Allow
  

我用了一个Enum.Format(typeof(FileSystemAccessRights),rule,"G")为了获得格式，有效地执行 ToString()，但我只是不确定这些数字是否正确。

输出上述内容的代码：

private static DirectorySecurity CheckWriteAccess(string backupPath)
{
    DirectorySecurity writeAccess = new DirectorySecurity( Path.GetDirectoryName(backupPath),AccessControlSections.Access);

    Console.WriteLine("Checking write access in this directory....");
    foreach (FileSystemAccessRule rule in writeAccess.GetAccessRules(true, true, typeof(NTAccount)))
    {
        Console.WriteLine("{0} => {1}", Enum.Format(typeof(FileSystemRights),rule.FileSystemRights,"G"), rule.AccessControlType);
    }

    return writeAccess;
}

CAS IOPermisson 读/写仅授予您ability读或写。它不会注意到文件系统级别权限 (ACL)。仔细检查文件夹上的 ACL :)

-Oisin