On Wed, Sep 14, 2016 at 6:19 PM, Andy Lutomirski [off-list ref] wrote:

On Wed, Sep 14, 2016 at 3:14 PM, Mickaël Salaün [off-list ref] wrote:

quoted

On 14/09/2016 20:29, Andy Lutomirski wrote:

quoted

On Wed, Sep 14, 2016 at 12:24 AM, Mickaël Salaün [off-list ref] wrote:

quoted

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: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Kees Cook <redacted>
---

quoted

+       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