From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f171.google.com ([209.85.208.171]:44315 "EHLO mail-lj1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728272AbeINDCX (ORCPT ); Thu, 13 Sep 2018 23:02:23 -0400 Received: by mail-lj1-f171.google.com with SMTP id q127-v6so5876363ljq.11 for ; Thu, 13 Sep 2018 14:51:01 -0700 (PDT) MIME-Version: 1.0 References: <99cb1ae7-8881-eb9a-a8cb-a787abe454e1@schaufler-ca.com> In-Reply-To: From: Paul Moore Date: Thu, 13 Sep 2018 17:50:48 -0400 Message-ID: Subject: Re: [PATCH 10/10] LSM: Blob sharing support for S.A.R.A and LandLock To: Golden_Miller83@protonmail.ch Cc: keescook@chromium.org, casey@schaufler-ca.com, linux-security-module@vger.kernel.org, James Morris , linux-kernel@vger.kernel.org, selinux@tycho.nsa.gov, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, Stephen Smalley , linux-fsdevel@vger.kernel.org, casey.schaufler@intel.com Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Sep 13, 2018 at 4:58 PM Jordan Glover wrote: > > On Thursday, September 13, 2018 9:12 PM, Paul Moore wrote: > > > On Thu, Sep 13, 2018 at 11:19 AM Kees Cook keescook@chromium.org wrote: > > > > > On Thu, Sep 13, 2018 at 6:16 AM, Paul Moore paul@paul-moore.com wrote: > > > > > > > On Thu, Sep 13, 2018 at 12:19 AM Kees Cook keescook@chromium.org wrote: ... > > > > > I don't see a good reason to make this a config. Why shouldn't this > > > > > always be enabled? > > > > > > > > I do. From a user perspective it is sometimes difficult to determine > > > > the reason behind a failed operation; its is a DAC based denial, the > > > > LSM, or some other failure? Stacking additional LSMs has the > > > > potential to make this worse. The boot time configuration adds to the > > > > complexity. > > > > > > Let me try to convince you otherwise. :) The reason I think there's no > > > need for this is because the only functional change here is how > > > TOMOYO gets stacked. And in my proposal, we can convert TOMOYO to be > > > enabled/disabled like LoadPin. Given the configs I showed, stacking > > > TOMOYO with the other major LSMs becomes a config (and/or boottime) > > > option. > > > The changes for TOMOYO are still needed even with SECURITY_STACKING, > > > and I argue that the other major LSMs remain the same. It's only > > > infrastructure that has changed. So, I think having SECURITY_STACKING > > > actually makes things more complex internally (all the ifdefs, weird > > > enable logic) and for distros ("what's this stacking option", etc?) > > > > None of the above deals with the user experience or support burden a > > distro would have by forcing stacking on. If we make it an option the > > distros can choose for themselves; picking a kernel build config is > > not something new to distros, and I think Casey's text adequately > > explains CONFIG_SECURITY_STACKING in terms that would be sufficient. > > CONFIG_SECURITY_STACKING doesn't make any user visible changes on > itself as it doesn't automatically enable any new LSM. The LSM > specific configs are place where users/distros make decisions. If > there is only one LSM enabled to run then there's nothing to stack. > If someone choose to run two or more LSM in config/boot cmdline > then we can assume having it stacked is what they wanted. As Kees > pointed there is already CONFIG_SECURITY_DEFAULT_XXX. In both cases > CONFIG_SECURITY_STACKING is redundant and only adds burden instead > of removing it. See my last response to Kees. > > I currently have a neutral stance on stacking, making it mandatory > > pushes me more towards a "no". > > This implies that your real concern is something else than > CONFIG_SECURITY_STACKING which only allows you to ignore the whole > thing. Please reveal it. There are a lot of people waiting for LSM > stacking which is several years late and it would be great to > resolve potential issues earlier rather later. What? I resent the implication that I'm hiding anything; there are a lot of fair criticisms you could level at me, but I take offense at the idea that I'm not being honest here. I've been speaking with Casey, John, and others about stacking for years, both on-list and in-person at conferences, and my neutral-opinion-just-make-it-work-for-everything-and-make-it-optional stance has been pretty consistent and isn't new. Also, let's be really clear here: I'm only asking that stacking be made a build time option (as it is in Casey's patchset). That seems like a pretty modest ask for something so significant and "several years late" as you put it. -- paul moore www.paul-moore.com