From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Subject: Re: [RFC v3 19/22] landlock: Add interrupted origin
Date: Wed, 14 Sep 2016 18:19:14 -0700
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Cc: "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Alexei Starovoitov <ast-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>, Casey Schaufler <casey-iSGtlc1asvQWG2LlvL+J4A@public.gmane.org>, Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>, Daniel Mack <daniel-cYrQPVfZoowdnm+yROfE0A@public.gmane.org>, David Drysdale <drysdale-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, "David S . Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, Elena Reshetova <elena.reshetova-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "Eric W . Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>, James Morris <james.l.morris-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Paul Moore <pmoore-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Sargun Dhillon <sargun-GaZTRHToo+CzQB+pC5nmwQ@public.gmane.org>, "Serge E . Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Will Drewry <wad-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, "kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org" <kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org>Linux API <linu>
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On Wed, Sep 14, 2016 at 3:14 PM, Micka=C3=ABl Sala=C3=BCn <mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>=
 wrote:
>
> On 14/09/2016 20:29, Andy Lutomirski wrote:
>> On Wed, Sep 14, 2016 at 12:24 AM, Micka=C3=ABl Sala=C3=BCn <mic@digikod.=
net> 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: Micka=C3=ABl Sala=C3=BCn <mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
>>> Cc: Alexei Starovoitov <ast-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>>> Cc: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
>>> Cc: Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>
>>> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>>> ---
>>
>>
>>>
>>> +       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.

--Andy