RE: chattr immutable

[Glynn Clements <glynn@gclements.plus.com>]

Dermot Paikkos wrote:

> One of the other things I was hoping to do was deny users from renaming 
> the folder or the other classic mistake, accidently drag and drop a 
> folder into another folder.

Create, move, rename and delete are determined by the permissions on
the containing directory. It isn't possible to set different
restrictions for different files or subdirectories within a given
directory, nor allow creation but forbid deletion.

The only exception is that if the directory has the sticky bit set
(chmod +t), users cannot move, rename or delete a file or subdirectory
which they do not own.

If the user owns the directory, they can clear this flag, but that may
not be an issue if you're simply trying to prevent accidents rather
than deliberate acts.

However, it may prove problematic if there are plausible scenarios in
which files owned by another user can end up in the directory, as you
can end up with files which can only be removed by root.

> I can't think of a set of UNIX permission or smb.conf directives that is 
> going to allow make a directory readonly but allow a group to create 
> files within the directory.

Creating files within a directory directly contradicts the notion of
"read only".

You can get slightly more flexibility if you use POSIX ACLs rather
than the historical ugo/rwx permission model. You're still limited to
read/write/execute permission, but you can assign permissions to
multiple named users and to multiple named groups.

Also, Samba has a variety of configuration options which allow the
Unix permission model to be bypassed. E.g. the "dos filemode" option
allows any user with write permission on a file or directory to change
the permissions and/or owner.

-- 
Glynn Clements <glynn@gclements.plus.com>