linux-kernel - Re: [PATCH v4 3/4] kunit: Taint the kernel when KUnit tests are run

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Message-ID: <f361c4b7-12b8-0513-2025-4ed8025a67d1@riseup.net>
Date:   Fri, 1 Jul 2022 08:55:07 -0300
From:   Maíra Canal <mairacanal@...eup.net>
To:     David Gow <davidgow@...gle.com>
Cc:     "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Kees Cook <keescook@...omium.org>,
        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,
        Jonathan Corbet <corbet@....net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        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>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kbuild@...r.kernel.org,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>
Subject: Re: [PATCH v4 3/4] kunit: Taint the kernel when KUnit tests are run

On 7/1/22 05:47, 'David Gow' via KUnit Development wrote:
> Make KUnit trigger the new TAINT_TEST taint when any KUnit test is run.
> Due to KUnit tests not being intended to run on production systems, and
> potentially causing problems (or security issues like leaking kernel
> addresses), the kernel's state should not be considered safe for
> production use after KUnit tests are run.
> 
> This both marks KUnit modules as test modules using MODULE_INFO() and
> manually taints the kernel when tests are run (which catches builtin
> tests).
> 
> Acked-by: Luis Chamberlain <mcgrof@...nel.org>
> Tested-by: Daniel Latypov <dlatypov@...gle.com>
> Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
> Signed-off-by: David Gow <davidgow@...gle.com>
> ---

Tested with DRM KUnit tests on x86_64.

Tested-By: Maíra Canal <mairacanal@...eup.net>

Best Regards
- Maíra Canal

> 
> Changes since v3:
> https://lore.kernel.org/lkml/20220513083212.3537869-2-davidgow@google.com/
> - Use MODULE_INFO() for KUnit modules.
>   - This is technically redundant, as the KUnit executor will taint the
>     kernel when _any_ KUnit tests are run, but may be useful if some
>     other tool will parse the 'test' property.
> - Add {Acked,Tested,Reviewed}-by tags.
> 
> ---
>  include/kunit/test.h | 3 ++-
>  lib/kunit/test.c     | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 8ffcd7de9607..ccae848720dc 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -277,7 +277,8 @@ static inline int kunit_run_all_tests(void)
>  	{								\
>  		return __kunit_test_suites_exit(__suites);		\
>  	}								\
> -	module_exit(kunit_test_suites_exit)
> +	module_exit(kunit_test_suites_exit)				\
> +	MODULE_INFO(test, "Y");
>  #else
>  #define kunit_test_suites_for_module(__suites)
>  #endif /* MODULE */
> diff --git a/lib/kunit/test.c b/lib/kunit/test.c
> index a5053a07409f..8b11552dc215 100644
> --- a/lib/kunit/test.c
> +++ b/lib/kunit/test.c
> @@ -11,6 +11,7 @@
>  #include <kunit/test-bug.h>
>  #include <linux/kernel.h>
>  #include <linux/moduleparam.h>
> +#include <linux/panic.h>
>  #include <linux/sched/debug.h>
>  #include <linux/sched.h>
>  
> @@ -501,6 +502,9 @@ int kunit_run_tests(struct kunit_suite *suite)
>  	struct kunit_result_stats suite_stats = { 0 };
>  	struct kunit_result_stats total_stats = { 0 };
>  
> +	/* Taint the kernel so we know we've run tests. */
> +	add_taint(TAINT_TEST, LOCKDEP_STILL_OK);
> +
>  	if (suite->suite_init) {
>  		suite->suite_init_err = suite->suite_init(suite);
>  		if (suite->suite_init_err) {