Prevent deletion of Directory and Files

[abhilashca]

Hello,

I am using Dokan to show the files and directories that are on my remote server (or cloud) based on the target endpoint the app points to. I want to prevent the user from deleting Directory and Files that are listed in their virtual file system.

To prevent deletion of files and folder, I am checking for DeleteOnClose in CreateFile. Below is the code snippet I have in CreateFile.

public NtStatus CreateFile(...)
{
    string path = GetPath(fileName);

    if (options == FileOptions.DeleteOnClose)
    {
        info.DeleteOnClose = false;
        return NtStatus.AccessDenied;
    }

    // rest of the code follows
}

Now, when I try to delete a directory, I get below dialogs or prompts which is as expected.

Now, when I try to delete a file, I get below dialog with message - "Invalid MS-DOS function":

I think, the message "Invalid MS-DOS function" is shown because I haven't configured something properly.

Can anyone please help on how to show proper access denied error instead of "Invalid MS-DOS function".

Thanks in advance.

[Liryna]

Hi @abhilashca ,

You could look at the Procmon logs filtered on the file to see if anything looks suspicious. It might also be a good idea to implement GetFileSecurity and deny the delete action. You can even set the filesystem readonly at mount if you also do not want the user to write

[abhilashca]

Thank you for the reply @Liryna. Much appreciated. I have enabled DokanOptions.WriteProtection at the time of mounting the disk. This has taken care of all the edit/delete scenarios.

Now, when I try to save a text file, I am getting below error message:

Any idea why the error message talks about bad image instead of access denied.

[Liryna]

It looks like you have an invalid installation of dokan. The path for dokannp1 should be in system32.

[abhilashca]

I figured out the issue. Within ReadFile(), if any the files are outside my remote files, then I was returning Not Implemented.

I found this in my console - 12/17/2021 20:41:14 - [DokanNet] ReadFileProxy : \System32\System32\dokannp1.dll Return : NotImplemented ReadLength : 0

I think, I am good for now. Will reopen the ticket if I get stuck again. Thank you for the help. Much appreciated.