Re: [PATCH v11 07/12] seccomp: add SECCOMP_RET_ERRNO

[Kees Cook]

On Mon, Feb 27, 2012 at 9:11 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> On 02/24, Will Drewry wrote:
>>
>>  static u32 seccomp_run_filters(int syscall)
>>  {
>>       struct seccomp_filter *f;
>> -     u32 ret = SECCOMP_RET_KILL;
>>       static const struct bpf_load_fn fns = {
>>               bpf_load,
>>               sizeof(struct seccomp_data),
>>       };
>> +     u32 ret = SECCOMP_RET_ALLOW;
>>       const void *sc_ptr = (const void *)(uintptr_t)syscall;
>>
>> +     /* Ensure unexpected behavior doesn't result in failing open. */
>> +     if (unlikely(current->seccomp.filter == NULL))
>> +             ret = SECCOMP_RET_KILL;
>
> Is "seccomp.filter == NULL" really possible?

It should not be, but I'm much more comfortable with this failing
closed. I think it's important to be as defensive as possible with
this code given its intended use.

-Kees

-- 
Kees Cook
ChromeOS Security
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