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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 185EBC433EF for ; Thu, 18 Nov 2021 20:29:37 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4562961288 for ; Thu, 18 Nov 2021 20:29:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4562961288 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.openwall.com Received: (qmail 25871 invoked by uid 550); 18 Nov 2021 20:29:29 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 25837 invoked from network); 18 Nov 2021 20:29:28 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ext/hA9Hqh6Ihnib1lEscDhjZ8UYlTCVA8i531ovqfY=; b=DkxRs4QGBaUfZ5NxWhAUlvfgQ+APMPBEvDxf32GiR+ctjCEwclxDrBmpBI5JKbwmkA cgeVsSzBs3oMnWsbAcEi6WdQ1dxVJsjLPfAZOSuwU+Dl1qCX9ttV+fmrBLBCUbr0JuYq 3HhDrirsunWX4JcVtzu7DG9bT9AHSJBG0fGMk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ext/hA9Hqh6Ihnib1lEscDhjZ8UYlTCVA8i531ovqfY=; b=LN7C+4I8saxwnc4PmiuNV49KIJijOihsCLu9thkTotVfvB/Q2AFo6cjfSEal9fkI9Y gtw2bYACP3Kc8U/l7m6orRvvXvQIM1yBBXp+iBb3TEnXJiM1UmmrvqllGuhEUuazCADU uFHKFU4PvIKz7El0stExzb0SFQbRQr0VlAUVGmA0NV0z1kvzWWep1m/q5hgMHbbgniNS 5qICC3swMvVe6QESiluvMb76RJtCeKTA+qcPTIno5c2RyrNTlQqtlBo4NM4pB6MNVXH8 doum0v1p8fCjXc8q9AQ3La+g69vg6GFtcRbb+sstnhbC83dOO0p5Wrm9jEdU+qEq71oY TUtQ== X-Gm-Message-State: AOAM532wqkl5mVnzvoopzUKIqNjbabqxO675dDS9lurQgQdXShuarQdw KyKkbthS682vt1GIBI3SxFrO2g== X-Google-Smtp-Source: ABdhPJzhN6XTGPJ+t5Eac6rxPUFgxhIjU9/l/jeG/zY9bBf89ym/EhuXk+yjIpBbzu4TIjZmokStrA== X-Received: by 2002:a17:90b:1a87:: with SMTP id ng7mr14046093pjb.86.1637267355937; Thu, 18 Nov 2021 12:29:15 -0800 (PST) Date: Thu, 18 Nov 2021 12:29:14 -0800 From: Kees Cook To: Casey Schaufler Cc: Alexander Popov , Steven Rostedt , Linus Torvalds , Lukas Bulwahn , Jonathan Corbet , Paul McKenney , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Joerg Roedel , Maciej Rozycki , Muchun Song , Viresh Kumar , Robin Murphy , Randy Dunlap , Lu Baolu , Petr Mladek , Luis Chamberlain , Wei Liu , John Ogness , Andy Shevchenko , Alexey Kardashevskiy , Christophe Leroy , Jann Horn , Greg Kroah-Hartman , Mark Rutland , Andy Lutomirski , Dave Hansen , Will Deacon , Ard Biesheuvel , Laura Abbott , David S Miller , Borislav Petkov , Arnd Bergmann , Andrew Scull , Marc Zyngier , Jessica Yu , Iurii Zaikin , Rasmus Villemoes , Wang Qing , Mel Gorman , Mauro Carvalho Chehab , Andrew Klychkov , Mathieu Chouquet-Stringer , Daniel Borkmann , Stephen Kitt , Stephen Boyd , Thomas Bogendoerfer , Mike Rapoport , Bjorn Andersson , Kernel Hardening , linux-hardening@vger.kernel.org, "open list:DOCUMENTATION" , linux-arch , Linux Kernel Mailing List , linux-fsdevel , notify@kernel.org, main@lists.elisa.tech, safety-architecture@lists.elisa.tech, devel@lists.elisa.tech, Shuah Khan Subject: Re: [PATCH v2 0/2] Introduce the pkill_on_warn parameter Message-ID: <202111181226.D4538E2F@keescook> References: <77b79f0c-48f2-16dd-1d00-22f3a1b1f5a6@linux.com> <20211115110649.4f9cb390@gandalf.local.home> <202111151116.933184F716@keescook> <59534db5-b251-c0c8-791f-58aca5c00a2b@linux.com> <202111161037.7456C981@keescook> <202111180930.5FA3EF0F59@keescook> <16baa1f4-972d-c781-2d57-508296a83bfb@schaufler-ca.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16baa1f4-972d-c781-2d57-508296a83bfb@schaufler-ca.com> On Thu, Nov 18, 2021 at 10:30:32AM -0800, Casey Schaufler wrote: > On 11/18/2021 9:32 AM, Kees Cook wrote: > > On Tue, Nov 16, 2021 at 11:00:23AM -0800, Casey Schaufler wrote: > > > On 11/16/2021 10:41 AM, Kees Cook wrote: > > > > On Tue, Nov 16, 2021 at 12:12:16PM +0300, Alexander Popov wrote: > > > > > What if the Linux kernel had a LSM module responsible for error handling policy? > > > > > That would require adding LSM hooks to BUG*(), WARN*(), KERN_EMERG, etc. > > > > > In such LSM policy we can decide immediately how to react on the kernel error. > > > > > We can even decide depending on the subsystem and things like that. > > > > That would solve the "atomicity" issue the WARN tracepoint solution has, > > > > and it would allow for very flexible userspace policy. > > > > > > > > I actually wonder if the existing panic_on_* sites should serve as a > > > > guide for where to put the hooks. The current sysctls could be replaced > > > > by the hooks and a simple LSM. > > > Do you really want to make error handling a "security" issue? > > > If you add security_bug(), security_warn_on() and the like > > > you're begging that they be included in SELinux (AppArmor) policy. > > > BPF, too, come to think of it. Is that what you want? > > Yeah, that is what I was thinking. This would give the LSM a view into > > kernel state, which seems a reasonable thing to do. If system integrity > > is compromised, an LSM may want to stop trusting things. > > How are you planning to communicate the security relevance of the > warning to the LSM? I don't think that __FILE__, __LINE__ or __func__ > is great information to base security policy on. Nor is a backtrace. I think that would be part of the design proposal. Initially, the known parts are "warn or bug" and "pid". > > A dedicated error-handling LSM could be added for those hooks that > > implemented the existing default panic_on_* sysctls, and could expand on > > that logic for other actions. > > I can see having an interface like LSM for choosing a bug/warn policy. > I worry about expanding the LSM hook list for a case where I would > hope no existing LSM would use them, and the new LSM doesn't use any > of the existing hooks. Yeah, I can see that, though we've got a history of the "specialized" hooks getting used by other LSMs. (e.g. loadpin's stuff got hooked up to other LSMs, etc.) -- Kees Cook