Re: [PATCH v4 2/4] module: panic: Taint the kernel when selftest modules load

From: Luis Chamberlain <mcgrof@kernel.org>
To: David Gow <davidgow@google.com>
Cc: Brendan Higgins <brendanhiggins@google.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	"Guilherme G . Piccoli" <gpiccoli@igalia.com>,
	Sebastian Reichel <sre@kernel.org>,
	John Ogness <john.ogness@linutronix.de>,
	Joe Fradley <joefradley@google.com>,
	Daniel Latypov <dlatypov@google.com>,
	kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Lucas De Marchi <lucas.demarchi@intel.com>,
	Aaron Tomlin <atomlin@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kbuild@vger.kernel.org
Subject: Re: [PATCH v4 2/4] module: panic: Taint the kernel when selftest modules load
Date: Fri, 1 Jul 2022 15:30:13 -0700	[thread overview]
Message-ID: <Yr91dWijROn4gyLl@bombadil.infradead.org> (raw)
In-Reply-To: <20220701084744.3002019-2-davidgow@google.com>

On Fri, Jul 01, 2022 at 04:47:42PM +0800, David Gow wrote:
> Taint the kernel with TAINT_TEST whenever a test module loads, by adding
> a new "TEST" module property, and setting it for all modules in the
> tools/testing directory. This property can also be set manually, for
> tests which live outside the tools/testing directory with:
> MODULE_INFO(test, "Y");
> 
> Signed-off-by: David Gow <davidgow@google.com>
> ---
> 
> This patch is new in v4 of this series.
> 
> ---
>  kernel/module/main.c  | 8 ++++++++
>  scripts/mod/modpost.c | 3 +++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index fed58d30725d..f2ca0a3ee5e6 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -1988,6 +1988,14 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
>  	/* Set up license info based on the info section */
>  	set_license(mod, get_modinfo(info, "license"));
>  
> +	if (!get_modinfo(info, "test")) {
> +		if (!test_taint(TAINT_TEST))
> +			pr_warn("%s: loading test module taints kernel.\n",
> +				mod->name);

That seems pretty chatty, maybe just pr_warn_once() and make indicate
which is the first one? For kernel builds where their goal is to just
loop testing this will grow the kernel log without not much need.

  Luis

> +		add_taint_module(mod, TAINT_TEST, LOCKDEP_STILL_OK);
> +	}
> +
> +
>  	return 0;
>  }
>  
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 29d5a841e215..5937212b4433 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -2191,6 +2191,9 @@ static void add_header(struct buffer *b, struct module *mod)
>  
>  	if (strstarts(mod->name, "drivers/staging"))
>  		buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
> +
> +	if (strstarts(mod->name, "tools/testing"))
> +		buf_printf(b, "\nMODULE_INFO(test, \"Y\");\n");

Otherwise looks good, thanks for doing this!

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis