How to modify file access control in .NET Core

Question

I'm trying to change the permissions of a file in .NET Core. However, it seems that FileInfo doesn't have any SetAccessControl anymore.

// Create a new FileInfo object.
FileInfo fInfo = new FileInfo(FileName);

// Get a FileSecurity object that represents the 
// current security settings.
FileSecurity fSecurity = fInfo.GetAccessControl();

// Add the FileSystemAccessRule to the security settings. 
fSecurity.AddAccessRule(new FileSystemAccessRule(Account,
                                                Rights,
                                                ControlType));

// Set the new access settings.
fInfo.SetAccessControl(fSecurity);

The goal is just to add execution right to the current owner of a file (which is not Windows or Unix specific feature).

Any clues on how to do that on .NET Core ?

Answer 1

How to Get and modify User Group Other Rights on Windows

I finally implement the Windows file permission access:

1. Get the file security:

      var security = new FileSecurity(fileSystemInfoFullName, 
                AccessControlSections.Owner | 
                AccessControlSections.Group |
                AccessControlSections.Access);

2. Get the authorization rules:

var authorizationRules = security.GetAccessRules(true, true, typeof(NTAccount));

3. Get the authorization rules for the owner:

var owner = security.GetOwner(typeof(NTAccount));
foreach (AuthorizationRule rule in authorizationRules)
{
    FileSystemAccessRule fileRule = rule as FileSystemAccessRule;
    if (fileRule != null)
    {
        if (owner != null && fileRule.IdentityReference == owner)
        {
             if (fileRule.FileSystemRights.HasFlag(FileSystemRights.ExecuteFile) ||
                fileRule.FileSystemRights.HasFlag(FileSystemRights.ReadAndExecute) ||
                fileRule.FileSystemRights.HasFlag(FileSystemRights.FullControl))
            {
                ownerRights.IsExecutable = true;
            }
        }
        else if (group != null && fileRule.IdentityReference == group)
        {
            // TO BE CONTINUED...
        }
    }
}

4. Add a rule for owner:

security.ModifyAccessRule(AccessControlModification.Add,
    new FileSystemAccessRule(owner, FileSystemRights.Modify, AccessControlType.Allow),
    out bool modified);

5. Bonus

How to get the group and others, or ... my definition of something equivalent ?

var group = security.GetGroup(typeof(NTAccount));

var others = new SecurityIdentifier(WellKnownSidType.BuiltinUsersSid, null)
                 .Translate(typeof(NTAccount));

Note: This code comes from my open source project Lx.Shell

Answer 2

At this time there are two extension methods: GetAccessControl and SetAccessControl, for FileInfo, DirectoryInfo and etc.

So you can use var ac = new FileInfo(path).GetAccessControl(), this expression is valid both in .NET Framework and .Net Core. But you still need dotnet add package System.IO.FileSystem.AccessControl.

File.GetAccessControl isn't available in .NET Core.

ref: https://docs.microsoft.com/dotnet/api/system.io.filesystemaclextensions.getaccesscontrol

Answer 3

The FileSecurity class is now part of the System.IO.FileSystem.AccessControl package for .NET Core. There is no longer a File.GetAccessControl method so you will need to instanciate the FileSecurity instance yourself.

Answer 4

Another way to handle acls for directory or file:

       // Adds an ACL entry on the specified directory for the specified account.
    public static void AddDirectorySecurity(string FileName, string Account, FileSystemRights Rights, AccessControlType ControlType)
    {
        // Create a new DirectoryInfo object.
        DirectoryInfo dInfo = new DirectoryInfo(FileName);

        // Get a DirectorySecurity object that represents the 
        // current security settings.
        DirectorySecurity dSecurity = dInfo.GetAccessControl();

        // Add the FileSystemAccessRule to the security settings. 
        dSecurity.AddAccessRule(new FileSystemAccessRule(Account,
                                                        Rights,
                                                        ControlType));

        // Set the new access settings.
        dInfo.SetAccessControl(dSecurity);
    }

    // Removes an ACL entry on the specified directory for the specified account.
    public static void RemoveDirectorySecurity(string FileName, string Account, FileSystemRights Rights, AccessControlType ControlType)
    {
        // Create a new DirectoryInfo object.
        DirectoryInfo dInfo = new DirectoryInfo(FileName);

        // Get a DirectorySecurity object that represents the 
        // current security settings.
        DirectorySecurity dSecurity = dInfo.GetAccessControl();

        // Add the FileSystemAccessRule to the security settings. 
        dSecurity.RemoveAccessRule(new FileSystemAccessRule(Account,
                                                        Rights,
                                                        ControlType));

        // Set the new access settings.
        dInfo.SetAccessControl(dSecurity);
    }

    // Adds an ACL entry on the specified file for the specified account.
    public static void AddFileSecurity(string fileName, string account,
        FileSystemRights rights, AccessControlType controlType)
    {

        // Create a new FileInfo object.
        FileInfo fInfo = new FileInfo(fileName);

        // Get a FileSecurity object that represents the 
        // current security settings.
        FileSecurity fSecurity = fInfo.GetAccessControl();

        // Add the FileSystemAccessRule to the security settings.
        fSecurity.AddAccessRule(new FileSystemAccessRule(account,
            rights, controlType));

        // Set the new access settings.
        fInfo.SetAccessControl(fSecurity);
    }

    // Removes an ACL entry on the specified file for the specified account.
    public static void RemoveFileSecurity(string fileName, string account,
        FileSystemRights rights, AccessControlType controlType)
    {

        // Create a new FileInfo object.
        FileInfo fInfo = new FileInfo(fileName);

        // Get a FileSecurity object that represents the 
        // current security settings.
        FileSecurity fSecurity = fInfo.GetAccessControl();

        // Remove the FileSystemAccessRule from the security settings.
        fSecurity.RemoveAccessRule(new FileSystemAccessRule(account,
            rights, controlType));

        // Set the new access settings.
        fInfo.SetAccessControl(fSecurity);
    }

    //example for open onClick folderdialog and get owner by NTACCOUNT of folder from acl
    private async void Button_Click(object sender, RoutedEventArgs e)
    {
        var folderPicker = new Windows.Storage.Pickers.FolderPicker();
        folderPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.Desktop;
        folderPicker.FileTypeFilter.Add("*");

        Windows.Storage.StorageFolder folder = await folderPicker.PickSingleFolderAsync();
        if (folder != null)
        {
            // Application now has read/write access to all contents in the picked folder
            // (including other sub-folder contents)
            Windows.Storage.AccessCache.StorageApplicationPermissions.
            FutureAccessList.AddOrReplace("PickedFolderToken", folder);

            // Create a new FileInfo object.
            FileInfo fInfo = new FileInfo(folder.ToString());

            // Get a FileSecurity object that represents the 
            // current security settings.
            FileSecurity fSecurity = fInfo.GetAccessControl();

            IdentityReference identityReference = fSecurity.GetOwner(typeof(SecurityIdentifier));
            NTAccount ntAccount = identityReference.Translate(typeof(NTAccount)) as NTAccount;
            var fileOwner = ntAccount.Value;


            //do something with file Owner
            //this.tb1.Text = "folder: " + folder.Name + " in Pfad: " + folder.Path + "owned by: " + fileOwner;
        }
        else
        {
            //error Handler
        }

    }