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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 0AE4DC433E0 for ; Thu, 21 May 2020 20:00:34 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4E6FE20748 for ; Thu, 21 May 2020 20:00:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="arknal30" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E6FE20748 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-18847-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 1754 invoked by uid 550); 21 May 2020 20:00:27 -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 1731 invoked from network); 21 May 2020 20:00:27 -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=ulvs3QovAejney8/yaIpAssOKiAEegTNo53VZEhb45g=; b=arknal30qqyUt9Uultoin1W2eEnpjZOh2M50gfKNKsh2c05XoVw664fE7SmegYbFqL 1jYIOZFK3qvFTzSvZb1a/0TeRh7x1QwAIQ0yudjxW7Ohj3kbGc5wR0AnbDcmCs1eSjqo W43A5+fzigzpmM6CKgu4thGrBpPlM6zXWyDTc= 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=ulvs3QovAejney8/yaIpAssOKiAEegTNo53VZEhb45g=; b=F/BFa+at2BVVCsLeApL4Il+WoFBQZp7ruWLvz/lbJh6FRT7yZ7AITsF4uaZ2MinnFk 7XAjjVA3tfK2TMrZSDi60P2aXsWq3UEwmHiFyJsOHOvUHTzsozuAKvx3OhO30Y+F7jYa jSGlvAukTCLJISsyylspkeaGRRo0iiLTj+Tdl/9BkwIUY0xY2xQYqUFPHxQs9duM8kpY s/1/gpxRyyHnLWz61KEG6sJcjZUpX+Z22vGgOeNLKRnyRS6aHloMaua9kWNU39a5y3gH WlfMHl6L5P4ZJVsEueEujiwjm2cbSw4+dDBqKWtwOBKbCA9xxIniiY49qcnDAUb1Twnm k2/A== X-Gm-Message-State: AOAM532C5n1UKZD0ickmk62vvvbEiLvHQg+RLf3XQ2tYNVr7chXB/sb/ FxmZSgznKHySHaDrOJMYkgLZhw== X-Google-Smtp-Source: ABdhPJygsq417Det10M2bkwgpyvuYKzPNse7VchUrWVJXxj4vjS2acqQQI4FoLCeiaO83wNsdfO0qw== X-Received: by 2002:a17:90a:4fc6:: with SMTP id q64mr241368pjh.34.1590091215159; Thu, 21 May 2020 13:00:15 -0700 (PDT) Date: Thu, 21 May 2020 13:00:12 -0700 From: Kees Cook To: Kristen Carlson Accardi Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, Masahiro Yamada , Michal Marek , x86@kernel.org, "H. Peter Anvin" , arjan@linux.intel.com, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, Tony Luck , linux-kbuild@vger.kernel.org Subject: Re: [PATCH v2 4/9] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Message-ID: <202005211255.33E27D05@keescook> References: <20200521165641.15940-1-kristen@linux.intel.com> <20200521165641.15940-5-kristen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200521165641.15940-5-kristen@linux.intel.com> On Thu, May 21, 2020 at 09:56:35AM -0700, Kristen Carlson Accardi wrote: > Allow user to select CONFIG_FG_KASLR if dependencies are met. Change > the make file to build with -ffunction-sections if CONFIG_FG_KASLR > > Signed-off-by: Kristen Carlson Accardi > Reviewed-by: Tony Luck > Tested-by: Tony Luck > --- > Makefile | 4 ++++ > arch/x86/Kconfig | 13 +++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/Makefile b/Makefile > index 04f5662ae61a..28e515baa824 100644 > --- a/Makefile > +++ b/Makefile > @@ -862,6 +862,10 @@ ifdef CONFIG_LIVEPATCH > KBUILD_CFLAGS += $(call cc-option, -flive-patching=inline-clone) > endif > > +ifdef CONFIG_FG_KASLR > +KBUILD_CFLAGS += -ffunction-sections > +endif > + > # arch Makefile may override CC so keep this after arch Makefile is included > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 2d3f963fd6f1..50e83ea57d70 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -2183,6 +2183,19 @@ config RANDOMIZE_BASE > > If unsure, say Y. > > +config FG_KASLR > + bool "Function Granular Kernel Address Space Layout Randomization" > + depends on $(cc-option, -ffunction-sections) > + depends on RANDOMIZE_BASE && X86_64 > + help > + This option improves the randomness of the kernel text > + over basic Kernel Address Space Layout Randomization (KASLR) > + by reordering the kernel text at boot time. This feature > + uses information generated at compile time to re-layout the > + kernel text section at boot time at function level granularity. > + > + If unsure, say N. > + > # Relocation on x86 needs some additional build support > config X86_NEED_RELOCS > def_bool y Kconfig bikeshedding: how about putting FG_KASLR in arch/Kconfig, add a "depends on ARCH_HAS_FG_KASLR", and remove the arch-specific depends. Then in arch/x86 have ARCH_HAS_FG_KASLR as a def_bool y with the RANDOMIZE_BASE && X86_64 depends. This will more cleanly split the build elements (compiler flags) from the arch elements (64-bit x86, arch-specific flags, etc). With that split out: Reviewed-by: Kees Cook -- Kees Cook