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Message-ID: <CAGXu5j+90zJTcfm2DMP04zu0pg832dKgSJgfFYxLVvV=CZk16g@mail.gmail.com>
Date: Mon, 3 Oct 2016 16:46:26 -0700
From: Kees Cook <keescook@...omium.org>
To: Andy Lutomirski <luto@...capital.net>
Cc: Mickaël Salaün <mic@...ikod.net>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
Arnd Bergmann <arnd@...db.de>, Casey Schaufler <casey@...aufler-ca.com>,
Daniel Borkmann <daniel@...earbox.net>, Daniel Mack <daniel@...que.org>,
David Drysdale <drysdale@...gle.com>, "David S . Miller" <davem@...emloft.net>,
Elena Reshetova <elena.reshetova@...el.com>, "Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <james.l.morris@...cle.com>, Paul Moore <pmoore@...hat.com>,
Sargun Dhillon <sargun@...gun.me>, "Serge E . Hallyn" <serge@...lyn.com>, Tejun Heo <tj@...nel.org>,
Will Drewry <wad@...omium.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Linux API <linux-api@...r.kernel.org>,
LSM List <linux-security-module@...r.kernel.org>,
Network Development <netdev@...r.kernel.org>,
"open list:CONTROL GROUP (CGROUP)" <cgroups@...r.kernel.org>
Subject: Re: [RFC v3 19/22] landlock: Add interrupted origin
On Wed, Sep 14, 2016 at 6:19 PM, Andy Lutomirski <luto@...capital.net> wrote:
> On Wed, Sep 14, 2016 at 3:14 PM, Mickaël Salaün <mic@...ikod.net> wrote:
>>
>> On 14/09/2016 20:29, Andy Lutomirski wrote:
>>> On Wed, Sep 14, 2016 at 12:24 AM, Mickaël Salaün <mic@...ikod.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: Mickaël Salaün <mic@...ikod.net>
>>>> Cc: Alexei Starovoitov <ast@...nel.org>
>>>> Cc: Andy Lutomirski <luto@...capital.net>
>>>> Cc: Daniel Borkmann <daniel@...earbox.net>
>>>> Cc: Kees Cook <keescook@...omium.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.
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
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