Re: problems with changing UID/GID

[Florian Weimer <Weimer@CERT.Uni-Stuttgart.DE>]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> But, the credentials are per-task in Linux, so it's possible to have
>> two tasks in a process running under different UIDs.
>
> Really useful isnt it

And not supported by GNU libc, neither officially nor by the current
implementation. :-(

I'd really like to have an explicit parameter for all these process
attributes (the credentials, chroot, maybe something else I'm missing
here; some kind of handle is probably required).  chroot() on open()
wouldn't have to require privileges, so it could help web servers
quite a bit.

Some day, I'm going to implement something like this in userspace
(using a privileged daemon and file descriptor passing).  But
performance will be horrible.

-- 
Florian Weimer 	                  Weimer@CERT.Uni-Stuttgart.DE
University of Stuttgart           http://CERT.Uni-Stuttgart.DE/people/fw/
RUS-CERT                          fax +49-711-685-5898