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Date: Wed, 28 Feb 2018 00:09:13 +0000
From: Andy Lutomirski <>
To: Mickaël Salaün <>
Cc: Andy Lutomirski <>, LKML <>, 
	Alexei Starovoitov <>, Arnaldo Carvalho de Melo <>, 
	Casey Schaufler <>, Daniel Borkmann <>, 
	David Drysdale <>, "David S . Miller" <>, 
	"Eric W . Biederman" <>, James Morris <>, 
	Jann Horn <>, Jonathan Corbet <>, 
	Michael Kerrisk <>, Kees Cook <>, 
	Paul Moore <>, Sargun Dhillon <>, 
	"Serge E . Hallyn" <>, Shuah Khan <>, Tejun Heo <>, 
	Thomas Graf <>, Tycho Andersen <>, Will Drewry <>, 
	Kernel Hardening <>, Linux API <>, 
	LSM List <>, 
	Network Development <>
Subject: Re: [PATCH bpf-next v8 08/11] landlock: Add ptrace restrictions

On Wed, Feb 28, 2018 at 12:00 AM, Mickaël Salaün <> wrote:
> On 28/02/2018 00:23, Andy Lutomirski wrote:
>> On Tue, Feb 27, 2018 at 11:02 PM, Andy Lutomirski <> wrote:
>>> On Tue, Feb 27, 2018 at 10:14 PM, Mickaël Salaün <> wrote:
>>> 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

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