Re: [PATCH 4/6] BC: user interface (syscalls)

Alan Cox
2006-08-24T10:43:58Z

Ar Mer, 2006-08-23 am 21:35 -0700, ysgrifennodd Andrew Morton:
> > Its a uid_t because of setluid() and twenty odd years of existing unix
> > practice.
> >
>
> I don't understand. This number is an identifier for an accounting
> container, which was somehow dreamed up by userspace.

Which happens to be a uid_t. It could easily be anyother_t of itself and
you can create a container_id_t or whatever. It is just a number.

The ancient Unix implementations of this kind of resource management and
security are built around setluid() which sets a uid value that cannot
be changed again and is normally used for security purposes. That
happened to be a uid_t and in simple setups at login uid = luid = euid
would be the norm.

Thus the Linux one happens to be a uid_t. It could be something else but
for the "container per user" model whatever a container is must be able
to hold all possible uid_t values. So we can certainly do something like

typedef uid_t container_id_t;

Alan