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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E09FDC433E0 for ; Tue, 16 Jun 2020 08:39:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC2C620767 for ; Tue, 16 Jun 2020 08:39:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727857AbgFPIjC (ORCPT ); Tue, 16 Jun 2020 04:39:02 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:45213 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726112AbgFPIjB (ORCPT ); Tue, 16 Jun 2020 04:39:01 -0400 Received: from static-50-53-52-215.bvtn.or.frontiernet.net ([50.53.52.215] helo=[192.168.192.153]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jl77R-0005Ng-TC; Tue, 16 Jun 2020 08:38:58 +0000 Subject: Re: [PATCH 4/5] LSM: Define SELinux function to measure security state To: Mimi Zohar , Casey Schaufler , Lakshmi Ramasubramanian , Stephen Smalley Cc: Stephen Smalley , James Morris , linux-integrity@vger.kernel.org, LSM List , linux-kernel References: <20200613024130.3356-1-nramas@linux.microsoft.com> <20200613024130.3356-5-nramas@linux.microsoft.com> <2df1bc4f-675d-7868-de5b-1256346f982e@schaufler-ca.com> <1592243068.11061.155.camel@linux.ibm.com> From: John Johansen Autocrypt: addr=john.johansen@canonical.com; prefer-encrypt=mutual; keydata= LS0tLS1CRUdJTiBQR1AgUFVCTElDIEtFWSBCTE9DSy0tLS0tCgptUUlOQkU1bXJQb0JFQURB 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(Cc'ing John) > > On Mon, 2020-06-15 at 10:33 -0700, Casey Schaufler wrote: >> On 6/15/2020 9:45 AM, Lakshmi Ramasubramanian wrote: >>> On 6/15/20 4:57 AM, Stephen Smalley wrote: >>> >>> Hi Stephen, >>> >>> Thanks for reviewing the patches. >>> >>>>> +void security_state_change(char *lsm_name, void *state, int state_len) >>>>> +{ >>>>> +       ima_lsm_state(lsm_name, state, state_len); >>>>> +} >>>>> + >>>> >>>> What's the benefit of this trivial function instead of just calling >>>> ima_lsm_state() directly? >>> >>> One of the feedback Casey Schaufler had given earlier was that calling an IMA function directly from SELinux (or, any of the Security Modules) would be a layering violation. >> >> Hiding the ima_lsm_state() call doesn't address the layering. >> The point is that SELinux code being called from IMA (or the >> other way around) breaks the subsystem isolation. Unfortunately, >> it isn't obvious to me how you would go about what you're doing >> without integrating the subsystems. > > Casey, I'm not sure why you think there is a layering issue here. >  There were multiple iterations of IMA before it was upstreamed.  One > iteration had separate integrity hooks(LIM).  Only when the IMA calls > and the security hooks are co-located, are they combined, as requested > by Linus. > I don't see the layering violation here either, Casey has already responded and I don't have anything to add > There was some AppArmour discussion about calling IMA directly, but I > haven't heard about it in a while or seen the patch. > its lower priority than other work. I think calling IMA directly has use cases but must be done very carefully, and well reviewed. I have would have more concerns with IMA calling directly into the various LSMs.