linux-kernel - Re: [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE

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Message-ID: <CAGETcx_LQDdnaU+3JVGw+6=DJ8tRoQ00+3rD2gOiHHkWomt8jg@mail.gmail.com>
Date:   Tue, 13 Aug 2019 13:15:44 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Matthias Maennich <maennich@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, maco@...roid.com,
        Android Kernel Team <kernel-team@...roid.com>, arnd@...db.de,
        geert@...ux-m68k.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>, hpa@...or.com,
        jeyu@...nel.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        kstewart@...uxfoundation.org, linux-arch@...r.kernel.org,
        linux-kbuild@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
        linux-modules@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-usb@...r.kernel.org, lucas.de.marchi@...il.com,
        maco@...gle.com, michal.lkml@...kovi.net, mingo@...hat.com,
        oneukum@...e.com, pombredanne@...b.com, sam@...nborg.org,
        sboyd@...eaurora.org, Sandeep Patil <sspatil@...gle.com>,
        stern@...land.harvard.edu, tglx@...utronix.de,
        usb-storage@...ts.one-eyed-alien.net, x86@...nel.org,
        yamada.masahiro@...ionext.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        David Howells <dhowells@...hat.com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Dan Williams <dan.j.williams@...el.com>,
        Adrian Reber <adrian@...as.de>,
        Richard Guy Briggs <rgb@...hat.com>
Subject: Re: [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS

On Tue, Aug 13, 2019 at 5:19 AM 'Matthias Maennich' via kernel-team
<kernel-team@...roid.com> wrote:
>
> If MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS is enabled (default=n), the
> requirement for modules to import all namespaces that are used by
> the module is relaxed.
>
> Enabling this option effectively allows (invalid) modules to be loaded
> while only a warning is emitted.
>
> Disabling this option keeps the enforcement at module loading time and
> loading is denied if the module's imports are not satisfactory.
>
> Reviewed-by: Martijn Coenen <maco@...roid.com>
> Signed-off-by: Matthias Maennich <maennich@...gle.com>
> ---
>  init/Kconfig    | 14 ++++++++++++++
>  kernel/module.c | 11 +++++++++--
>  2 files changed, 23 insertions(+), 2 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index bd7d650d4a99..b3373334cdf1 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -2119,6 +2119,20 @@ config MODULE_COMPRESS_XZ
>
>  endchoice
>
> +config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
> +       bool "Allow loading of modules with missing namespace imports"
> +       default n
> +       help
> +         Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
> +         a namespace. A module that makes use of a symbol exported with such a
> +         namespace is required to import the namespace via MODULE_IMPORT_NS().
> +         This option relaxes this requirement when loading a module.

> While
> +         technically there is no reason to enforce correct namespace imports,
> +         it creates consistency between symbols defining namespaces and users
> +         importing namespaces they make use of.

I'm confused by this sentence. It sounds like it's the opposite of
what the config is doing? Can you please reword it for clarify?

-Saravana