[OpenAFS-devel] Re: MEMORY credential cache interop between Heimdal and MIT?

[Jeffrey Hutzelman]

On Thursday, August 30, 2007 02:26:57 PM -0400 Jim Rees <rees@umich.edu> 
wrote:

> Steve Simmons wrote:
>
>   It's how UNIX in general used to work (chown allowing you to give
>   away files) up through v7.
>
> You've got it backwards.  Unix never allowed users to give away files up
> through v7.  That ability was introduced in System III.

... and persists to this day in SVR4-derived systems.  There's nothing 
insecure about it, as long as the proper semantics are obeyed.  For 
example, systems which permit this also turn off the setid bits when the 
owner of a file is changed.

The restriction that only privileged users can change the owner of a file 
was reintroduced in BSD and remains in pretty much every system that 
dervies from it.  As far as I've been able to tell, this was done primarily 
to prevent users from giving away files to circumvent UID-based disk 
quotas, which were also introduced in BSD.

-- Jeff