[kernel-hardening] Re: [PATCH net-next v6 09/11] seccomp: Enhance test_harness with an assert step mechanism

["Mickaël Salaün" <mic@digikod.net>]

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On 20/04/2017 00:02, Kees Cook wrote:
> On Wed, Apr 19, 2017 at 2:51 PM, Mickaël Salaün <mic@digikod.net> wrote:
>>
>> On 19/04/2017 02:02, Kees Cook wrote:
>>> On Tue, Mar 28, 2017 at 4:46 PM, Mickaël Salaün <mic@digikod.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@digikod.net>
>>>> Cc: Andy Lutomirski <luto@amacapital.net>
>>>> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
>>>> Cc: Kees Cook <keescook@chromium.org>
>>>> Cc: Shuah Khan <shuah@kernel.org>
>>>> Cc: Will Drewry <wad@chromium.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!
> 
> -Kees
> 
> 

Good, in which place and name would it fit better?


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