Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs

From: Eric W. Biederman
Date: Thu Oct 22 2015 - 15:44:13 EST


Daniel Borkmann <daniel@xxxxxxxxxxxxx> writes:

> On 10/20/2015 08:56 PM, Eric W. Biederman wrote:
> ...
>> Just FYI: Using a device for this kind of interface is pretty
>> much a non-starter as that quickly gets you into situations where
>> things do not work in containers. If someone gets a version of device
>> namespaces past GregKH it might be up for discussion to use character
>> devices.
>
> Okay, you are referring to this discussion here:
>
> http://thread.gmane.org/gmane.linux.kernel.containers/26760

That is a piece of it. It is an old old discussion (which generally has
been handled poorly). For the forseeable future device namespaces have
a firm NACK by GregKH. Which means that dynamic character device based
interfaces do not work in containers. Which means if you are not
talking about physical hardware, character devices are a poor fit.

Making a character based interface for eBPF not workable.

Eric

p.s. There are plenty of reasons (even if privilege remains a
requirement) to ask how can this functionality be used in a
container. If for no other reason than sandboxing privileged
applications is typically a good idea.
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