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

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Message-ID: <20231018053146.GA16765@lst.de>
Date:   Wed, 18 Oct 2023 07:31:46 +0200
From:   Christoph Hellwig <hch@....de>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Christoph Hellwig <hch@....de>,
        Luis Chamberlain <mcgrof@...nel.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 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.