Re: [RFC v3 19/22] landlock: Add interrupted origin

[Kees Cook]

On Wed, Sep 14, 2016 at 6:19 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Wed, Sep 14, 2016 at 3:14 PM, MickaÃl SalaÃn <mic@xxxxxxxxxxx> wrote:
>>
>> On 14/09/2016 20:29, Andy Lutomirski wrote:
>>> On Wed, Sep 14, 2016 at 12:24 AM, MickaÃl SalaÃn <mic@xxxxxxxxxxx> wrote:
>>>> This third origin of hook call should cover all possible trigger paths
>>>> (e.g. page fault). Landlock eBPF programs can then take decisions
>>>> accordingly.
>>>>
>>>> Signed-off-by: MickaÃl SalaÃn <mic@xxxxxxxxxxx>
>>>> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
>>>> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>>>> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
>>>> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
>>>> ---
>>>
>>>
>>>>
>>>> +       if (unlikely(in_interrupt())) {
>>>
>>> IMO security hooks have no business being called from interrupts.
>>> Aren't they all synchronous things done by tasks?  Interrupts are
>>> driver things.
>>>
>>> Are you trying to check for page faults and such?
>>
>> Yes, that was the idea you did put in my mind. Not sure how to deal with
>> this.
>>
>
> It's not so easy, unfortunately.  The easiest reliable way might be to
> set a TS_ flag on all syscall entries when TIF_SECCOMP or similar is
> set.

For making this series smaller, let's leave the idea idea of interrupt
hooks out -- the intention is for stricter syscall filtering, yes?

Once things are more well established and there's a use-case for this,
it can be added back in.

-Kees


-- 
Kees Cook
Nexus Security