linux-kernel - Re: [PATCH v2 0/4] seccomp trap to userspace

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Date:   Fri, 18 May 2018 16:03:13 +0200
From:   Christian Brauner <christian@...uner.io>
To:     Tycho Andersen <tycho@...ho.ws>
Cc:     linux-kernel@...r.kernel.org,
        containers@...ts.linux-foundation.org,
        "Tobin C . Harding" <me@...in.cc>,
        Kees Cook <keescook@...omium.org>,
        Akihiro Suda <suda.akihiro@....ntt.co.jp>,
        Oleg Nesterov <oleg@...hat.com>,
        Andy Lutomirski <luto@...capital.net>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Tyler Hicks <tyhicks@...onical.com>
Subject: Re: [PATCH v2 0/4] seccomp trap to userspace

On Thu, May 17, 2018 at 09:12:14AM -0600, Tycho Andersen wrote:
> Hi,
> 
> After a while focusing on other things, I finally managed ot get a v2 of
> this series prepared. I believe I've addressed all the feedback from v1,
> except for one major point: switching the communication protocol over
> the fd to nlattr. I looked into doing this, but the kernel stuff for
> dealing with nlattr seems to require an skb (via nlmsg_{new,put} and
> netlink_unicast), which means we need to deal with the netlink sequence
> numbers, portids, and create a socket protocol. I can do this if we
> still think nlattr is necessary, but based on looking at it, it seems
> like a lot of extra code for no real benefit.

Yes, we've had that discussion before and I agree. I fail to see the
benefit here too.

Christian

> 
> I've also added support for passing fds. The code itself is simple, but
> the API could/should probably be different, see patch 4 for discussion.
> 
> Tycho
> 
> Tycho Andersen (4):
>   seccomp: add a return code to trap to userspace
>   seccomp: make get_nth_filter available outside of CHECKPOINT_RESTORE
>   seccomp: add a way to get a listener fd from ptrace
>   seccomp: add support for passing fds via USER_NOTIF
> 
>  arch/Kconfig                                  |   7 +
>  include/linux/seccomp.h                       |  14 +-
>  include/uapi/linux/ptrace.h                   |   2 +
>  include/uapi/linux/seccomp.h                  |  20 +-
>  kernel/ptrace.c                               |   4 +
>  kernel/seccomp.c                              | 480 +++++++++++++++++-
>  tools/testing/selftests/seccomp/seccomp_bpf.c | 359 ++++++++++++-
>  7 files changed, 878 insertions(+), 8 deletions(-)
> 
> -- 
> 2.17.0
> 
> _______________________________________________
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> Containers@...ts.linux-foundation.org
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