linux-kernel - Re: [PATCH net-next v6 09/11] seccomp: Enhance test

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Message-ID: <94ac6ddc-eaac-8548-f83f-826ddf05ac69@digikod.net>
Date:   Wed, 19 Apr 2017 23:51:35 +0200
From:   Mickaël Salaün <mic@...ikod.net>
To:     Kees Cook <keescook@...omium.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>,
        Shuah Khan <shuah@...nel.org>, 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 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?



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