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[209.85.219.177]) by smtp.gmail.com with ESMTPSA id f82-v6sm2184227ywf.58.2018.09.13.17.06.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Sep 2018 17:06:17 -0700 (PDT) Received: by mail-yb1-f177.google.com with SMTP id o17-v6so4077817yba.2 for ; Thu, 13 Sep 2018 17:06:17 -0700 (PDT) X-Received: by 2002:a25:2c3:: with SMTP id 186-v6mr124647ybc.421.1536883576941; Thu, 13 Sep 2018 17:06:16 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a25:5f04:0:0:0:0:0 with HTTP; Thu, 13 Sep 2018 17:06:16 -0700 (PDT) In-Reply-To: References: <99cb1ae7-8881-eb9a-a8cb-a787abe454e1@schaufler-ca.com> <0eb75e66-ed50-4013-6440-38bc2f814c6f@canonical.com> From: Kees Cook Date: Thu, 13 Sep 2018 17:06:16 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 10/10] LSM: Blob sharing support for S.A.R.A and LandLock To: Casey Schaufler Cc: John Johansen , Paul Moore , linux-security-module , James Morris , LKML , SE Linux , Tetsuo Handa , Stephen Smalley , "linux-fsdevel@vger.kernel.org" , Alexey Dobriyan , "Schaufler, Casey" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 13, 2018 at 5:03 PM, Casey Schaufler wrote: > On 9/13/2018 4:51 PM, Kees Cook wrote: >> So, before we can really make a decision, I think we have to decide: >> should ordering be arbitrary for even this level of stacking? > > Do we have a case where it matters? I know that I could write a > module that would have issues if one hook got called and another > didn't because because a precursor module hook failed. I don't > think that any of the existing modules have this problem. FWIW, I prefer having explicit ordering that cannot be changed at runtime. I'm just concerned about painting ourselves (further) into a corner with security= suddenly gaining ordering semantics, but maybe I can just ignore this and we can point and laugh at anyone who gets burned by some future change to making it order-sensitive. :) -Kees -- Kees Cook Pixel Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: keescook@chromium.org (Kees Cook) Date: Thu, 13 Sep 2018 17:06:16 -0700 Subject: [PATCH 10/10] LSM: Blob sharing support for S.A.R.A and LandLock In-Reply-To: References: <99cb1ae7-8881-eb9a-a8cb-a787abe454e1@schaufler-ca.com> <0eb75e66-ed50-4013-6440-38bc2f814c6f@canonical.com> Message-ID: To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Thu, Sep 13, 2018 at 5:03 PM, Casey Schaufler wrote: > On 9/13/2018 4:51 PM, Kees Cook wrote: >> So, before we can really make a decision, I think we have to decide: >> should ordering be arbitrary for even this level of stacking? > > Do we have a case where it matters? I know that I could write a > module that would have issues if one hook got called and another > didn't because because a precursor module hook failed. I don't > think that any of the existing modules have this problem. FWIW, I prefer having explicit ordering that cannot be changed at runtime. I'm just concerned about painting ourselves (further) into a corner with security= suddenly gaining ordering semantics, but maybe I can just ignore this and we can point and laugh at anyone who gets burned by some future change to making it order-sensitive. :) -Kees -- Kees Cook Pixel Security