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Date: Wed, 19 Apr 2017 18:50:37 -0700
From: Kees Cook <keescook@...omium.org>
To: Mickaël Salaün <mic@...ikod.net>,
Shuah Khan <shuah@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
Andy Lutomirski <luto@...capital.net>, Arnaldo Carvalho de Melo <acme@...nel.org>,
Casey Schaufler <casey@...aufler-ca.com>, Daniel Borkmann <daniel@...earbox.net>,
David Drysdale <drysdale@...gle.com>, "David S . Miller" <davem@...emloft.net>,
"Eric W . Biederman" <ebiederm@...ssion.com>, James Morris <james.l.morris@...cle.com>,
Jann Horn <jann@...jh.net>, Jonathan Corbet <corbet@....net>, Matthew Garrett <mjg59@...f.ucam.org>,
Michael Kerrisk <mtk.manpages@...il.com>, Paul Moore <paul@...l-moore.com>,
Sargun Dhillon <sargun@...gun.me>, "Serge E . Hallyn" <serge@...lyn.com>, Tejun Heo <tj@...nel.org>,
Thomas Graf <tgraf@...g.ch>, Will Drewry <wad@...omium.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Linux API <linux-api@...r.kernel.org>,
linux-security-module <linux-security-module@...r.kernel.org>,
Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v6 09/11] seccomp: Enhance test_harness with an
assert step mechanism
On Wed, Apr 19, 2017 at 3:05 PM, Mickaël Salaün <mic@...ikod.net> wrote:
>
>
> On 20/04/2017 00:02, Kees Cook wrote:
>> On Wed, Apr 19, 2017 at 2:51 PM, Mickaël Salaün <mic@...ikod.net> wrote:
>>>
>>> On 19/04/2017 02:02, Kees Cook wrote:
>>>> On Tue, Mar 28, 2017 at 4:46 PM, Mickaël Salaün <mic@...ikod.net> wrote:
>>>>> This is useful to return an information about the error without being
>>>>> able to write to TH_LOG_STREAM.
>>>>>
>>>>> Helpers from test_harness.h may be useful outside of the seccomp
>>>>> directory.
>>>>>
>>>>> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
>>>>> Cc: Andy Lutomirski <luto@...capital.net>
>>>>> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
>>>>> Cc: Kees Cook <keescook@...omium.org>
>>>>> Cc: Shuah Khan <shuah@...nel.org>
>>>>> Cc: Will Drewry <wad@...omium.org>
>>>>> ---
>>>>> tools/testing/selftests/seccomp/test_harness.h | 8 +++++++-
>>>>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/seccomp/test_harness.h b/tools/testing/selftests/seccomp/test_harness.h
>>>>> index a786c69c7584..77e407663e06 100644
>>>>> --- a/tools/testing/selftests/seccomp/test_harness.h
>>>>> +++ b/tools/testing/selftests/seccomp/test_harness.h
>>>>> @@ -397,7 +397,7 @@ struct __test_metadata {
>>>>> const char *name;
>>>>> void (*fn)(struct __test_metadata *);
>>>>> int termsig;
>>>>> - int passed;
>>>>> + __s8 passed;
>>>>
>>>> Why the reduction here? int is signed too?
>>>
>>> Because the return code of a process is capped to 8 bits and I use a
>>> negative value to not mess with the current interpretation of 0 (error)
>>> and 1 (OK) for the "passed" variable.
>>>
>>>>
>>>>> int trigger; /* extra handler after the evaluation */
>>>>> struct __test_metadata *prev, *next;
>>>>> };
>>>>> @@ -476,6 +476,12 @@ void __run_test(struct __test_metadata *t)
>>>>> "instead of by signal (code: %d)\n",
>>>>> t->name,
>>>>> WEXITSTATUS(status));
>>>>> + } else if (t->passed < 0) {
>>>>> + fprintf(TH_LOG_STREAM,
>>>>> + "%s: Failed at step #%d\n",
>>>>> + t->name,
>>>>> + t->passed * -1);
>>>>> + t->passed = 0;
>>>>> }
>>>>
>>>> Instead of creating an overloaded mechanism here, perhaps have an
>>>> option reporting mechanism that can be enabled. Like adding to
>>>> __test_metadata "bool no_stream; int test_number;" and adding
>>>> test_number++ to each ASSERT/EXCEPT call, and doing something like:
>>>>
>>>> if (t->no_stream) {
>>>> fprintf(TH_LOG_STREAM,
>>>> "%s: Failed at step #%d\n",
>>>> t->name,
>>>> t->test_number);
>>>> }
>>>>
>>>> It'd be a cleaner approach, maybe?
>>>
>>> Good idea, we will then be able to use 255 steps!
>>>
>>> Do you want me to send this as a separate patch?
>>>
>>> Can we move test_harness.h outside of the seccomp directory to be
>>> available to other subsystems as well?
>>
>> Yeah, I would do two patches, and send them out separately (to shuah
>> with lkml and me in cc at least), one to move test_hardness.h into
>> some include/ directory, and then to add the new logic for streamless
>> reporting.
>>
>> Thanks!
>>
>
> Good, in which place and name would it fit better?
I've added Shuah to CC. Shuah, where should a common header file for
selftests live? Should a new "include" directory be added?
-Kees
--
Kees Cook
Pixel Security
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