linux-kernel - Re: [PATCH v3 1/3] panic: Taint kernel if tests are run

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Yn561lzWDuiVdTHT@bombadil.infradead.org>
Date:   Fri, 13 May 2022 08:35:50 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     David Gow <davidgow@...gle.com>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        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>,
        "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
Subject: Re: [PATCH v3 1/3] panic: Taint kernel if tests are run

On Fri, May 13, 2022 at 04:32:11PM +0800, David Gow wrote:
> Most in-kernel tests (such as KUnit tests) are not supposed to run on
> production systems: they may do deliberately illegal things to trigger
> errors, and have security implications (for example, KUnit assertions
> will often deliberately leak kernel addresses).
> 
> Add a new taint type, TAINT_TEST to signal that a test has been run.
> This will be printed as 'N' (originally for kuNit, as every other
> sensible letter was taken.)
> 
> This should discourage people from running these tests on production
> systems, and to make it easier to tell if tests have been run
> accidentally (by loading the wrong configuration, etc.)
> 
> Signed-off-by: David Gow <davidgow@...gle.com>
> ---
> 
> Updated this to handle the most common case of selftest modules, in
> addition to KUnit tests. There's room for other tests or test frameworks
> to use this as well, either with a call to add_taint() from within the
> kernel, or by writing to /proc/sys/kernel/tainted.
> 
> The 'N' character for the taint is even less useful now that it's no
> longer short for kuNit, but all the letters in TEST are taken. :-(
> 
> Changes since v2:
> https://lore.kernel.org/linux-kselftest/20220430030019.803481-1-davidgow@google.com/
> - Rename TAINT_KUNIT -> TAINT_TEST.
> - Split into separate patches for adding the taint, and triggering it.
> - Taint on a kselftest_module being loaded (patch 3/3)
> 
> Changes since v1:
> https://lore.kernel.org/linux-kselftest/20220429043913.626647-1-davidgow@google.com/
> - Make the taint per-module, to handle the case when tests are in
>   (longer lasting) modules. (Thanks Greg KH).
> 
> Note that this still has checkpatch.pl warnings around bracket
> placement, which are intentional as part of matching the surrounding
> code.
> 
> ---
>  Documentation/admin-guide/tainted-kernels.rst | 1 +
>  include/linux/panic.h                         | 3 ++-
>  kernel/panic.c                                | 1 +
>  3 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
> index ceeed7b0798d..546f3071940d 100644
> --- a/Documentation/admin-guide/tainted-kernels.rst
> +++ b/Documentation/admin-guide/tainted-kernels.rst
> @@ -100,6 +100,7 @@ Bit  Log  Number  Reason that got the kernel tainted
>   15  _/K   32768  kernel has been live patched
>   16  _/X   65536  auxiliary taint, defined for and used by distros
>   17  _/T  131072  kernel was built with the struct randomization plugin
> + 18  _/N  262144  an in-kernel test (such as a KUnit test) has been run

I think mentioning just kunit fuzzes its interpretation here.
Best to keep that out.

Other than that:

Acked-by: Luis Chamberlain <mcgrof@...nel.org>

  Luis