linux-kernel - Re: [PATCH v5 4/4] selftest: Taint kernel when test module loaded

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Message-ID: <CAFd5g44q5EPS=v_DDUxBJnO1htMSyB=GNXpP0KkVNuOapehk-A@mail.gmail.com>
Date:   Wed, 6 Jul 2022 16:51:42 -0400
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     David Gow <davidgow@...gle.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Sebastian Reichel <sre@...nel.org>,
        John Ogness <john.ogness@...utronix.de>,
        Joe Fradley <joefradley@...gle.com>,
        Daniel Latypov <dlatypov@...gle.com>,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Aaron Tomlin <atomlin@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v5 4/4] selftest: Taint kernel when test module loaded

On Sat, Jul 2, 2022 at 12:10 AM David Gow <davidgow@...gle.com> wrote:
>
> Make any kselftest test module (using the kselftest_module framework)
> taint the kernel with TAINT_TEST on module load.
>
> Also mark the module as a test module using MODULE_INFO(test, "Y") so
> that other tools can tell this is a test module. We can't rely solely
> on this, though, as these test modules are also often built-in.
>
> Finally, update the kselftest documentation to mention that the kernel
> should be tainted, and how to do so manually (as below).
>
> Note that several selftests use kernel modules which are not based on
> the kselftest_module framework, and so will not automatically taint the
> kernel.
>
> This can be done in two ways:
> - Moving the module to the tools/testing directory. All modules under
>   this directory will taint the kernel.
> - Adding the 'test' module property with:
>   MODULE_INFO(test, "Y")
>
> Similarly, selftests which do not load modules into the kernel generally
> should not taint the kernel (or possibly should only do so on failure),
> as it's assumed that testing from user-space should be safe. Regardless,
> they can write to /proc/sys/kernel/tainted if required.
>
> Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>
> Signed-off-by: David Gow <davidgow@...gle.com>

Acked-by: Brendan Higgins <brendanhiggins@...gle.com>