[PATCH v7 2/9] seccomp: split filter prep from check and apply

[Kees Cook]

On Thu, Jun 26, 2014 at 5:37 AM, David Drysdale <drysdale at google.com> wrote:
> On Mon, Jun 23, 2014 at 02:58:06PM -0700, Kees Cook wrote:
>> In preparation for adding seccomp locking, move filter creation away
>> from where it is checked and applied. This will allow for locking where
>> no memory allocation is happening. The validation, filter attachment,
>> and seccomp mode setting can all happen under the future locks.
>>
>> Signed-off-by: Kees Cook <keescook at chromium.org>
>> ---
>>  kernel/seccomp.c |   97 +++++++++++++++++++++++++++++++++++++-----------------
>>  1 file changed, 67 insertions(+), 30 deletions(-)
>>
>> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
>> index afb916c7e890..edc8c79ed16d 100644
>> --- a/kernel/seccomp.c
>> +++ b/kernel/seccomp.c
>> @@ -515,6 +551,7 @@ static long seccomp_set_mode(unsigned long seccomp_mode, char __user *filter)
>>       current->seccomp.mode = seccomp_mode;
>>       set_thread_flag(TIF_SECCOMP);
>>  out:
>> +     seccomp_filter_free(prepared);
>>       return ret;
>>  }
>
> I think this needs to be inside #ifdef CONFIG_SECCOMP_FILTER to match
> the definition of seccomp_filter_free:
>
> ../kernel/seccomp.c:554:2: error: implicit declaration of function ‘seccomp_filter_free’ [-Werror=implicit-function-declaration]

Thanks for catching that! I've ended up rearranging the patch series
so the prepare/attach split happens after I've split the set_mode
functions now, so I've managed to avoid this condition now. :)

-Kees

-- 
Kees Cook
Chrome OS Security