chgrp resets the setuid and getgid bits

[Ben Stringer]

On Tue, 2006-07-25 at 14:43 +0300, Markku Kolkka wrote:
> Ben Stringer kirjoitti viestissään (lähetysaika tiistai, 25. 
> heinäkuuta 2006 12:44):
> > I observed this today on an RHEL4 system, and it applies to
> > Fedora also. I don't understand why this occurs - is it a
> > security feature?
> 
> It behaves as defined in the Single Unix Specification: 
> http://www.opengroup.org/onlinepubs/009695399/utilities/chgrp.html
> "Unless chgrp is invoked by a process with appropriate 
> privileges, the set-user-ID and set-group-ID bits of a regular 
> file shall be cleared upon successful completion; the 
> set-user-ID and set-group-ID bits of other file types may be 
> cleared."

Thanks for the references Markku.

In the example I gave, I created the file as root, then performed the
chgrp as root. root was a member of both of the groups I used in the
example. In what way was this example not "a process with appropriate
privileges"?

Cheers, Ben