[systemd-devel] Compatibility between D-Bus and kdbus

Lennart Poettering mzqohf at 0pointer.de
Wed Nov 26 11:42:42 PST 2014

On Wed, 26.11.14 11:08, Thiago Macieira (thiago at kde.org) wrote:

> On Wednesday 26 November 2014 19:30:16 Lennart Poettering wrote:
> > > I must be misunderstanding something.
> > 
> > The kernel enforces that each bus name is prefixed with "$UID-". This
> > is why the system bus is /sys/fs/kdbus/0-system rather than just
> > /sys/fs/kdbus/system.
> > 
> > This makes sure that users cannot play games with other users.
> Thanks for the clarification. That tidbit is nowhere in the
> kdbus.txt docs. It should probably be mentioned in the section about
> creating buses.

Added now.

> Also, shouldn't CAP_IPC_OWNER-privileged processes be able to create a bus 
> with an arbitrary  name?

We thought about that too, but then stepped away from it, in order to
avoid potential namespace clashes with additional files we might want
to place in the kdbusfs file system in the future. Given that there's
a strict regime now how the userspace objects are named we have
freedom picking names for new files we want to introduce from the
kernel-side, as long as we don't name thew new files

Also, it's another thing where being strict initially is a good thing,
since opening stuff up later is easier than closing it down later.


Lennart Poettering, Red Hat

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