linux-kernel - Re: [PATCH 1/2] module: Restrict module namespace access to in-tree modules

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Message-ID: <CAK7LNATRkZHwJGpojCnvdiaoDnP+aeUXgdey5sb_8muzdWTMkA@mail.gmail.com>
Date: Wed, 9 Jul 2025 00:35:25 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Matthias Maennich <maennich@...gle.com>, Jonathan Corbet <corbet@....net>, 
	Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
	Sami Tolvanen <samitolvanen@...gle.com>, Daniel Gomez <da.gomez@...sung.com>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas.schier@...ux.dev>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	Christoph Hellwig <hch@...radead.org>, Peter Zijlstra <peterz@...radead.org>, 
	David Hildenbrand <david@...hat.com>, Shivank Garg <shivankg@....com>, 
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>, Stephen Rothwell <sfr@...b.auug.org.au>, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org, 
	linux-kbuild@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] module: Restrict module namespace access to in-tree modules

On Wed, Jul 9, 2025 at 12:08 AM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> On 7/8/25 14:41, Masahiro Yamada wrote:
> > On Tue, Jul 8, 2025 at 4:29 PM Vlastimil Babka <vbabka@...e.cz> wrote:
> >>
> >> The module namespace support has been introduced to allow restricting
> >> exports to specific modules only, and intended for in-tree modules such
> >> as kvm. Make this intention explicit by disallowing out of tree modules
> >> both for the module loader and modpost.
> >>
> >> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> >
> >
> >
> > In my understanding, an external module with the same name
> > can override the internal one.
> >
> > This change disallows such a use-case.
>
> Hmm I'm not familiar with this, but for such cases to be legitimate we can
> assume the external module has to be derived from the internal one and not
> something completely unrelated impersonating the internal one? So in that
> case just patch 2 alone would be sufficient and not break any legitimate use
> cases?
>

IIRC, nvdimm uses this feature for testing.


In-tree drivers:
  drivers/nvdimm/Makefile

Out-of-tree drivers:
  tools/testing/nvdimm/Makefile
  tools/testing/nvdimm/Kbuild




-- 
Best Regards
Masahiro Yamada