linux-kernel - Re: [PATCH 5/5] modules: only allow symbol_get of EXPORT_SYMBOL

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Date:   Wed, 18 Oct 2023 11:25:46 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Christoph Hellwig <hch@....de>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Manuel Lauss <manuel.lauss@...il.com>,
        Yangbo Lu <yangbo.lu@....com>,
        Joshua Kinard <kumba@...too.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arm-kernel@...ts.infradead.org,
        open list <linux-kernel@...r.kernel.org>,
        linux-mmc@...r.kernel.org, netdev@...r.kernel.org,
        linux-rtc@...r.kernel.org, linux-modules@...r.kernel.org
Subject: Re: [PATCH 5/5] modules: only allow symbol_get of EXPORT_SYMBOL_GPL
 modules

On Wed, Oct 18, 2023 at 07:31:46AM +0200, Christoph Hellwig wrote:
> On Wed, Oct 18, 2023 at 01:30:18AM +0100, David Woodhouse wrote:
> > 
> > But if we're going to tolerate the core kernel still exporting some
> > stuff with EXPORT_SYMBOL, why isn't OK for a GPL-licensed module do to
> > the same? Even an *in-tree* GPL-licensed module now can't export
> > functionality with EXPORT_SYMBOL and have it used with symbol_get().
> 
> Anything using symbol_get is by intent very deeply internal for tightly
> coupled modules working together, and thus not a non-GPL export.
> 
> In fact the current series is just a stepping stone.  Once some mess
> in the kvm/vfio integration is fixed up we'll require a new explicit
> EXPORT_SYMBOL variant as symbol_get wasn't ever intended to be used
> on totally random symbols not exported for use by symbol_get.

The later patches in the series also show we could resolves most
uses through Kconfig and at build time, it really begs the question
if we even need it for any real valid uses.

  Luis