On Wed, Feb 28, 2018 at 12:00 AM, Mickaël Salaün [off-list ref] wrote:

On 28/02/2018 00:23, Andy Lutomirski wrote:

quoted

On Tue, Feb 27, 2018 at 11:02 PM, Andy Lutomirski [off-list ref] wrote:

quoted

On Tue, Feb 27, 2018 at 10:14 PM, Mickaël Salaün [off-list ref] wrote:

quoted

I think you're wrong here.  Any sane container trying to use Landlock
like this would also create a PID namespace.  Problem solved.  I still
think you should drop this patch.

Containers is one use case, another is build-in sandboxing (e.g. for web
browser…) and another one is for sandbox managers (e.g. Firejail,
Bubblewrap, Flatpack…). In some of these use cases, especially from a
developer point of view, you may want/need to debug your applications
(without requiring to be root). For nested Landlock access-controls
(e.g. container + user session + web browser), it may not be allowed to
create a PID namespace, but you still want to have a meaningful
access-control.

The consideration should be exactly the same as for normal seccomp.
If I'm in a container (using PID namespaces + seccomp) and a run a web
browser, I can debug the browser.

If there's a real use case for adding this type of automatic ptrace
protection, then by all means, let's add it as a general seccomp
feature.