Problem with setting up namespaces

Johannes Schlatow schlatow at
Thu Jul 18 21:00:19 CEST 2013

Thanks Björn.

The problem I have is not lua specific though. I was not only trying to
pass the client capability via namespaces (which works perfectly as you
just demonstrated) but also to register the server capability of an
ipc_gate to the server's namespace.

Basically, I don't want the server to create the ipc_gate by itself.
Instead I have another (trusted) application that has access to both
namespaces (i.e. the one of the server and the one of the client). This
application creates the ipc_gate and registers its capability with
appropriate rights to the corresponding namespaces.

The lua config I sent initially was just my approach to reproduce this
problem without posting too much of my code and to minimize the PEBKAC
factor ;)


On Thu, 18 Jul 2013 18:53:37 +0200
Björn Döbel <doebel at> wrote:

> Hash: SHA1
> Hi Johannes,
> >> Well, I want to provide capabilities for an application by
> >> putting them into a local namespace. Since our system changes
> >> dynamically I want to add capabilities at runtime by registering
> >> them to the corresponding namespace.
> please find attached the clntsrv example adapted to use namespaces.
> The general approach is:
> 1) In the Lua config create an empty namespace and make it accessible
>    to your application(s). Note that the example also uses different
>    access rights for client and server.
> 2) On the server side I use the object registry's register_object()
>    function, which internally creates an IPC gate and binds the
> calling thread to it. Then I use the namespace's register_object()
> call to make the new channel externally visible.
> 3) In the client I query for the object name. This call blocks until
>    the server has registered the new channel.
> Apart from these steps, client and server implementation are identical
> to the original example.
> Regarding your approach of putting a channel into the namespace within
> the Lua config file: This does not work for me. We are still trying to
> figure out, why. It's probably indeed be related to the downgrading as
> suggested by Christian.
> Bjoern
> Version: GnuPG v1.4.12 (GNU/Linux)
> Comment: Using GnuPG with Mozilla -
> Ys8An2vS/Uqj5qrFyKVxFAvGBB0BgtE0
> =0Qez

More information about the l4-hackers mailing list