Question

我在.NET 3.5中试用了Windows 7中的FileIOPermission。我一直是Windows XP用户，因为我是管理员而被授予此权限

我编写了以下代码，测试是否可以写入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();
}

因此该程序会导致UnauthorizedAccessException（我期望），但我不明白的是Demand()允许权限，SecurityManager确认授予了权限，但是在执行File.Copy()时，我确实得到了例外。

虽然我很高兴看到.NET阻止了我，但为什么在我打电话给Demand()之前它没有通知我？

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\..............

有人可以帮我理解为什么我会收到相互矛盾的信息吗？

-

更新 - 格林尼治标准时间19:30

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，我有权阅读它。但是，我试图使用此代码查看备份路径的权限和显然，我得到一个例外，因为我的备份（目标）文件实际上不存在，所以我无法检查权限在它上面。

我接下来会尝试另一个建议，将此检查移到另一种方法中。

更新 - 格林尼治标准时间19:45

我已将读/写需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;
}

这些都毫无例外地返回。

因此，如果.NET Security增强了DACL，我想知道为什么它会认为它会成功，如果实际上它不是。

-

更新19:57 GMT

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（使用来自.GetAccessRules（）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

我使用Enum.Format(typeof(FileSystemAccessRights),rule,"G")来获取格式，有效地执行ToString（），但我不确定这些数字是否正确。

输出上述代码：

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;
}

Answer 1

读取/写入的CAS IOPermisson仅允许能力进行读取或写入。它不需要注意文件系统级别权限（ACL）。仔细检查文件夹上的ACL：）

-Oisin

无法复制文件，即使在C＃中授予了FileIOPermission

1 个答案: