linux-kernel - Re: [GIT PULL 05/17 for v6.19] namespaces

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Message-ID: <87ecperpid.fsf@email.froward.int.ebiederm.org>
Date: Mon, 01 Dec 2025 13:06:02 -0600
From: "Eric W. Biederman" <ebiederm@...ssion.com>
To: Christian Brauner <brauner@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
 linux-fsdevel@...r.kernel.org,  linux-kernel@...r.kernel.org,
 Linux Containers <containers@...ts.linux.dev> 
Subject: Re: [GIT PULL 05/17 for v6.19] namespaces

Christian Brauner <brauner@...nel.org> writes:

> Hey Linus,
>
> /* Summary */
> This contains substantial namespace infrastructure changes including a new
> system call, active reference counting, and extensive header cleanups.
> The branch depends on the shared kbuild branch for -fms-extensions
> support.

I am missing something.  From the description it looks like
you are making nested containers impossible once this feature
is adopted.  Because the container will be able to see all of
the other namespaces and thus to see outside of it's own namespace.

The reason such as system call has not been introduced in the past
is because it introduces the namespace of namespace problem.

How have you solved the namespace of namespaces problem?

If you want nesting of containers the listing of namespaces very
much must be incomplete.

I haven't looked at reviewed or looked at the code yet because
the code was not posted in any of the usual places for container
development, nor was I copied.

Can you please describe how you are avoiding the namespace of namespaces
problem?

Eric