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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 19C06C433E2 for ; Wed, 22 Jul 2020 19:43:12 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 6855E20714 for ; Wed, 22 Jul 2020 19:43:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="UQTdPm/n" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6855E20714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19420-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 11598 invoked by uid 550); 22 Jul 2020 19:43:05 -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 11572 invoked from network); 22 Jul 2020 19:43:04 -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=j8EVfDnsbKkDzkQmKYCo8r+kuzC3a5xUIaeiauPjHyg=; b=UQTdPm/nC+HkSL2BrWnoVYlDw4QRQrGAqDirB5zm5BpUzgtCvJy4d6xrBDUdh5Guck /So1K/Y/MIZEeY8A8JAEnjxncJ8eGOce7xc0/mjnlbSh3Wd2At8ckPa28ZKIzSZ4bf/0 ZywAUOxsQOzs1FswGb+32DSfL9xYxikcwziYE= 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; bh=j8EVfDnsbKkDzkQmKYCo8r+kuzC3a5xUIaeiauPjHyg=; b=ihrY1glHxhQIyqNodzCP6EFgudwDrk+4b7aTzZZ4cxStUJ3zpFWJJbYHPjmjkRf+NZ mRVJt1W4FswYyF52eGjLFo9DWnAmwzDwI0vVIrKWMOqX9+GMeeXX/vOi0vB2MFyK1RoL vWvNXfNXKiFt1rtP1sGCrM16EgFoTuX65CjaAmoBeAcQUxHkZn29W1MAvHRVFl9Al8gi uu8mRaVHIeB6un0bi49ZAQ4nXTNQS4FRK0W6UjLLr/DgRLWkIHYa69l7OWXPY6hpFhIT IFGbXjsOBYQrKHu3rCdDs7OfO4qWKQl6C143TL3dCCarMhSY1YFLoIYX0G1T2jpy980/ t9wg== X-Gm-Message-State: AOAM533yPk7mlGrfFqdDdrQb79F2t1fEnUOtXFKiZzD+ML0s76OMmg0+ LV7BN2vhlnicI+BVIN4zkasxbQ== X-Google-Smtp-Source: ABdhPJwNDMuWHpZri+I/lnXdThH9TpOPI3+GSq/C/NGpYVJ4A3ptfCQ9jBQki7H6FXs3LEtMLCmGWw== X-Received: by 2002:a17:90b:2350:: with SMTP id ms16mr903643pjb.127.1595446972510; Wed, 22 Jul 2020 12:42:52 -0700 (PDT) Date: Wed, 22 Jul 2020 12:42:50 -0700 From: Kees Cook To: Josh Poimboeuf Cc: Miroslav Benes , Kristen Carlson Accardi , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arjan@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, live-patching@vger.kernel.org Subject: Re: [PATCH v4 00/10] Function Granular KASLR Message-ID: <202007221241.EBC2215A@keescook> References: <20200717170008.5949-1-kristen@linux.intel.com> <202007220738.72F26D2480@keescook> <20200722160730.cfhcj4eisglnzolr@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200722160730.cfhcj4eisglnzolr@treble> On Wed, Jul 22, 2020 at 11:07:30AM -0500, Josh Poimboeuf wrote: > On Wed, Jul 22, 2020 at 07:39:55AM -0700, Kees Cook wrote: > > On Wed, Jul 22, 2020 at 11:27:30AM +0200, Miroslav Benes wrote: > > > Let me CC live-patching ML, because from a quick glance this is something > > > which could impact live patching code. At least it invalidates assumptions > > > which "sympos" is based on. > > > > In a quick skim, it looks like the symbol resolution is using > > kallsyms_on_each_symbol(), so I think this is safe? What's a good > > selftest for live-patching? > > The problem is duplicate symbols. If there are two static functions > named 'foo' then livepatch needs a way to distinguish them. > > Our current approach to that problem is "sympos". We rely on the fact > that the second foo() always comes after the first one in the symbol > list and kallsyms. So they're referred to as foo,1 and foo,2. Ah. Fun. In that case, perhaps the LTO series has some solutions. I think builds with LTO end up renaming duplicate symbols like that, so it'll be back to being unique. -- Kees Cook