bug#865: 23.0.60; The directory is unsafe today

[Jason Rumney]

Stefan Monnier wrote:
> > This is impossible on Windows, AFAIK.  There are special flags to the
> > syscall that opens a file or directory that can bypass any denied
> > rights to enter a directory or open a file.  (These flags allegedly
> > exist so that system backup and restore programs could DTRT without
> > running as a privileged user.)
> >     
>
> Are you saying that anybody can read any file (or dir) simply by using
> those extra flags when they open those files and dirs?  So there's no
> possible privacy between users on the same machine?  If so, we may just
> stop to worry about server-ensure-safe-dir under w32 since there's
> simply no way for it to be safe (short of encrypting it, which implies
> a fairly different UI).
>   

I don't know the full details of NTFS security, but there is a special 
group called "Backup Users", which I would expect to be linked with the 
use of these flags somehow.