From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EC51C43441 for ; Wed, 10 Oct 2018 16:55:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B3D92087D for ; Wed, 10 Oct 2018 16:55:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tycho-ws.20150623.gappssmtp.com header.i=@tycho-ws.20150623.gappssmtp.com header.b="jimTMOTN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B3D92087D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tycho.ws Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-security-module-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726854AbeJKASD (ORCPT ); Wed, 10 Oct 2018 20:18:03 -0400 Received: from mail-ot1-f66.google.com ([209.85.210.66]:41546 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726666AbeJKASD (ORCPT ); Wed, 10 Oct 2018 20:18:03 -0400 Received: by mail-ot1-f66.google.com with SMTP id c32so6042594otb.8 for ; Wed, 10 Oct 2018 09:55:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tycho-ws.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=NXBnbT+4zx9IwFrqmamONNal5xOn+MriYyeH0v83R0c=; b=jimTMOTNQ1m68+Ab/EeICBeCnCO+fW6mtWGNAMG7KfyH/ytdfpfIU9n1qTPeAdl9et 6bWOLUMgzXKdX0MviICKEK0spND0WhvrlGdsJzBL+rIjqd95tq4RMMsn61izjL+4pCr8 RHCh3FPMjKXTjuSM0UzIxIrVbG3RbfbHQEnIOKWWgId+XcSwneYjnKSL6AYHPrzL20By ySC5iko4EyOoHewtV4A09/oxrWJR4AHf0B6oc+4Kqvyh6Wpht2QOARIoVUHmxv2ioBur 0WwBF3I2ZxSVsv7bTgUtQWp031I1YLipzNrr/BOMPQ9JMwIQ55QlbozrIAxA8KmJ2fYd KK1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=NXBnbT+4zx9IwFrqmamONNal5xOn+MriYyeH0v83R0c=; b=Mt1tpMITdypt8KQBI7Jt9zKQG2ta4Hd3Dba+IUiNayyIefJLzMk8bGp8PoHViH23V+ l9FRbqbLLcDuJ5CQAIq4JbJER8X1ykbfjJtnRB7BieNo/U3xFdbsXVG510YsIOhJcR4w YvRfnl+jYY1T/T6beWNtKSuc5+0bBaKW+hbIFQi1ExceMUQgYXwQPKagLAsNidNNEhB8 TMAnSeUczL0h/4ek/b+nxFdNt9YBA97FKkMEM4ETXIASbFt/DguPnRS225HuGc1PinTc lDPClNtybg+9vQMmjVuUJ2RcjaUCXo5aO3rHe8lOjjA7ulxf3UoOxX9Wo9KQHo69+qQX XV0g== X-Gm-Message-State: ABuFfojXNeg7wohlEpsamvhRcSmLUJgIn+QzGvAX100mA9EGX1VABLGQ 2wknLfYaO8S2zTD4ur0jkjZCpw== X-Google-Smtp-Source: ACcGV61/kJ2LH5LXGI6I1z/hk+jeY3iShJR2Q4y5i2YLIzmgZoJ6SwwkmEL344mvpfznJUaHvjWNSQ== X-Received: by 2002:a9d:d52:: with SMTP id 76mr21724977oti.326.1539190502056; Wed, 10 Oct 2018 09:55:02 -0700 (PDT) Received: from cisco ([2001:420:28e:1260:c7c:88c5:50e7:459f]) by smtp.gmail.com with ESMTPSA id 31-v6sm8062145ota.23.2018.10.10.09.54.58 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 10 Oct 2018 09:55:00 -0700 (PDT) Date: Wed, 10 Oct 2018 09:54:58 -0700 From: Tycho Andersen To: Christian Brauner Cc: Jann Horn , Paul Moore , Kees Cook , Linux API , containers@lists.linux-foundation.org, suda.akihiro@lab.ntt.co.jp, Oleg Nesterov , kernel list , "Eric W. Biederman" , linux-fsdevel@vger.kernel.org, Christian Brauner , Andy Lutomirski , linux-security-module , selinux@tycho.nsa.gov, Stephen Smalley , Eric Paris Subject: Re: [PATCH v7 3/6] seccomp: add a way to get a listener fd from ptrace Message-ID: <20181010165458.GA5607@cisco> References: <20181008162147.ubfxxsv2425l2zsp@brauner.io> <20181008181815.pwnqxngj22mhm2vj@brauner.io> <20181009132850.fp6yne2vgmfpi27k@brauner.io> <20181010153956.zzlatxdlcwolbs6k@brauner.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181010153956.zzlatxdlcwolbs6k@brauner.io> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Wed, Oct 10, 2018 at 05:39:57PM +0200, Christian Brauner wrote: > On Wed, Oct 10, 2018 at 05:33:43PM +0200, Jann Horn wrote: > > On Wed, Oct 10, 2018 at 5:32 PM Paul Moore wrote: > > > On Tue, Oct 9, 2018 at 9:36 AM Jann Horn wrote: > > > > +cc selinux people explicitly, since they probably have opinions on this > > > > > > I just spent about twenty minutes working my way through this thread, > > > and digging through the containers archive trying to get a good > > > understanding of what you guys are trying to do, and I'm not quite > > > sure I understand it all. However, from what I have seen, this > > > approach looks very ptrace-y to me (I imagine to others as well based > > > on the comments) and because of this I think ensuring the usual ptrace > > > access controls are evaluated, including the ptrace LSM hooks, is the > > > right thing to do. > > > > Basically the problem is that this new ptrace() API does something > > that doesn't just influence the target task, but also every other task > > that has the same seccomp filter. So the classic ptrace check doesn't > > work here. > > Just to throw this into the mix: then maybe ptrace() isn't the right > interface and we should just go with the native seccomp() approach for > now. Please no :). I don't buy your arguments that 3-syscalls vs. one is better. If I'm doing this setup with a new container, I have to do clone(CLONE_FILES), do this seccomp thing, so that my parent can pick it up again, then do another clone without CLONE_FILES, because in the general case I don't want to share my fd table with the container, wait on the middle task for errors, etc. So we're still doing a bunch of setup, and it feels more awkward than ptrace, with at least as many syscalls, and it only works for your children. I don't mind leaving capable(CAP_SYS_ADMIN) for the ptrace() part, though. So if that's ok, then I think we can agree :) Tycho