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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 E5FD9C43387 for ; Wed, 19 Dec 2018 15:42:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8E0A20449 for ; Wed, 19 Dec 2018 15:42:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="j63Gn2l2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729011AbeLSPmw (ORCPT ); Wed, 19 Dec 2018 10:42:52 -0500 Received: from mail-ot1-f68.google.com ([209.85.210.68]:36058 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728901AbeLSPmw (ORCPT ); Wed, 19 Dec 2018 10:42:52 -0500 Received: by mail-ot1-f68.google.com with SMTP id k98so19503360otk.3 for ; Wed, 19 Dec 2018 07:42:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=lWnRzvW4psFPteidosePoiiMR9ds84EA7gzyRM6GOdc=; b=j63Gn2l2ao7etptiekM9aTaVO630uoAgQRJJOWBO101RWLN9DkoebS1cb4E6fWdgYR Gn52lhOj2ukc/zgvwabznBEtHoLSlnx78QoI9zE3UQ/j+hDLYLuAYm+SxXaxPCcgeNqk CoQ1P5HYdO0WrGe0SdhvuH3N5qAkSORVGZJ4RUg7danObIrrFoon3D7H20OgSiXhPdnF o0Q5miBIJ3yO+GuAlTKK+SrBIfUtvvXx/p3GeCH1aqQiXpKQmdemvQ+yq0og0qtTO4bh mMO2rMpEHNLf3qUZcQfSLZPAFA1uqQfIwKal5AmG72ZGL4NY5y7Q8kB686G0BnlIU1A0 cLGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lWnRzvW4psFPteidosePoiiMR9ds84EA7gzyRM6GOdc=; b=F3/wuqR5aJfyqahLd8yAHie1Hmi1DbOW/HbBcT85i6GLmTiEV6T7kJruk9GVC7qVRK AndJksRgsZ4f47MTE2rhyZBIqfYKoAE/iMcpubSFH8ydQEgnivjh0SnV08p2mroTFdr4 UZuBFGlgWLtd0nJzBM0eDddVGL+VPQ1UCSKCCiqhlEHHZyF3PSlwa8Dj/Zl+SJmJlNmD pZisD9zrasjxf0LECL1UA6y+7oT6rZCJJQH2RysBelx8ypiYPP0MlfyEsaa5LDolfvzW kpUGiWlPuAvf2gbljBeQ1AE8O3nu8MrwFCs0ij4hOYv4OY+6/A5xcHaHIzi3WTBYwjBy irlA== X-Gm-Message-State: AA+aEWb0Loacep7nvjeA0lyUMUGP+YLe+PU9b9rGb2FxCkUTBUt5OKye bd7AQ2rWPFhKNLdEAI8iJUPowRDCiTYWGfhdK4Bglw== X-Google-Smtp-Source: AFSGD/XO8QkM3oYdrQZr8PaZdmx+9mp5QbzKx6SMhJsi7R/4EjDz4HjMscYCeu4Pn/sX/mSWY4BymfEcQNWz/uFH+qA= X-Received: by 2002:a9d:1ea7:: with SMTP id n36mr15517940otn.217.1545234170669; Wed, 19 Dec 2018 07:42:50 -0800 (PST) MIME-Version: 1.0 References: <1544736761-7920-1-git-send-email-william.c.roberts@intel.com> <877d53f9-3296-368c-979f-cf73cfc50ebb@tycho.nsa.gov> <20181219091224.GA1887@ncase> In-Reply-To: <20181219091224.GA1887@ncase> From: William Roberts Date: Wed, 19 Dec 2018 07:42:39 -0800 Message-ID: Subject: Re: [PATCH 1/2] Makefile: fix _FORTIFY_SOURCE redefined build error To: Patrick Steinhardt Cc: Stephen Smalley , selinux@vger.kernel.org, William Roberts , James Carter Content-Type: text/plain; charset="UTF-8" Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Wed, Dec 19, 2018 at 1:12 AM Patrick Steinhardt wrote: > > Hi, > > On Tue, Dec 18, 2018 at 08:03:54AM -0800, William Roberts wrote: > > Patrick, > > > > Hoping you could maybe weigh in on your choice for bypassing the > > compiler driver with -Wp and not setting _FORTIFY_SOURCE to something > > like 1 or 2? > > > > I'm seeing this issue on Ubuntu 16.04.5: > > :0:0: error: "_FORTIFY_SOURCE" redefined [-Werror] > > > > gcc version: > > gcc (Ubuntu 5.4.0-6ubuntu1~16.04.10) 5.4.0 20160609 > > > > My thought is to undef/redef _FORTIFY_SOURCE in CFLAGS and set the > > level to 2. Setting CFLAGS via the env/make arg will override this > > behavior > > and use CFLAGS as is. > > I used "-Wp" simply because it was existing previously, so I just > stuck to what was there already. The original issue I had was > that Gentoo Hardened, as Jason notes, already defines > _FORTIFY_SOURCE as part of the compiler spec. Due to that, I was > seeing a lot of warnings. > > So I set the flag to a simple define without setting a specific > value, which _seemed_ to let the issue go away. But going back to > the initial issue, this didn't seem to have solved it correctly. > Dunno what I've been doing back then to not see the warnings > after my change anymore, but I noticed that they have resurface > recently. > > So I guess the real fix would be to redefine the value by first > undef'ing it and then redefining it to the desired value. And I > do agree that in that case, we should simply revert to > _FORTIFY_SOURCE=2. > > Patrick > > > On Fri, Dec 14, 2018 at 8:02 AM William Roberts > > wrote: > > > > > > On Fri, Dec 14, 2018 at 6:32 AM Stephen Smalley wrote: > > > > > > > > On 12/14/18 8:43 AM, Stephen Smalley wrote: > > > > > On 12/13/18 4:32 PM, bill.c.roberts@gmail.com wrote: > > > > >> From: William Roberts > > > > >> > > > > >> Certain builds of gcc enable _FORTIFY_SOURCE which results in the error: > > > > >> :0:0: warning: "_FORTIFY_SOURCE" redefined > > > > >> :0:0: note: this is the location of the previous definition > > > > >> > > > > >> Correct this by undefining it first and redefining it. Also, the previous > > > > >> command line option was using -Wp which passing the value *AS IS* to the > > > > >> pre-processor rather than to the compiler driver. The C pre-processor has > > > > >> an undocumented interface subject to change per man 1 gcc. Just use the > > > > >> -D option as is. > > > > > > > > > > See commit ca07a2ad46be141dad90d885dd33a2ac31c6559a ("libselinux: avoid > > > > > redefining _FORTIFY_SOURCE") for why we don't specify a value for > > > > > _FORTIFY_SOURCE here. Not sure about the -Wp,-D vs -D rationale. > > > > > > I'm not 100% convinced that the patch is the best solution or the commit message > > > is describing the problem correctly. I could also be understanding it > > > wrong here. > > > The man page is saying not to bypass the compiler driver via -Wp, and I don't > > > see a good reason for it either. > > > > > > See my comments below, they feed back into this. > > > > > > > > > > > I guess the issue here is that we want to provide sane defaults for > > > > building without breaking the build when others specify their own > > > > definitions and without weakening those definitions. By undefining and > > > > re-defining, it seems like we might weaken existing builds that were > > > > specifying 2. > > > > > > We conditionally assign to CFLAGS via ?= operator. Thus, CFLAGS and the > > > corresponding addition of EXTRA_CFLAGS which contains the undef/def > > > is not appended. CFLAGS specified via the environment or as an argument to > > > make will cause this assignment not to occur (via ?= semantics) and whatever > > > they specify for CFLAGS is sent to CC. > > > > > > Here is some sample output: > > > make CFLAGS='-D_FORTIFY_SOURCE=2' > > > cc -D_FORTIFY_SOURCE=2 -I../include -D_GNU_SOURCE -DNO_ANDROID_BACKEND > > > -fPIC -DSHARED -c -o stringrep.lo stringrep.c > > > > > > With that said, *i think its safe* to bump it back to '-D_FORTIFY_SOURCE=2' I agree that 2 is the better value. I'll re-roll these to use 2. No one seems to be complaining on using the -D/-U options. > > > > > > > > > > > > > > > > >> > > > > >> Signed-off-by: William Roberts > > > > >> --- > > > > >> libselinux/src/Makefile | 2 +- > > > > >> libselinux/utils/Makefile | 2 +- > > > > >> 2 files changed, 2 insertions(+), 2 deletions(-) > > > > >> > > > > >> diff --git a/libselinux/src/Makefile b/libselinux/src/Makefile > > > > >> index 977b5c8cfcca..ee55bd0dbff7 100644 > > > > >> --- a/libselinux/src/Makefile > > > > >> +++ b/libselinux/src/Makefile > > > > >> @@ -64,7 +64,7 @@ ifeq ($(COMPILER), gcc) > > > > >> EXTRA_CFLAGS = -fipa-pure-const -Wlogical-op > > > > >> -Wpacked-bitfield-compat -Wsync-nand \ > > > > >> -Wcoverage-mismatch -Wcpp -Wformat-contains-nul -Wnormalized=nfc > > > > >> -Wsuggest-attribute=const \ > > > > >> -Wsuggest-attribute=noreturn -Wsuggest-attribute=pure > > > > >> -Wtrampolines -Wjump-misses-init \ > > > > >> - -Wno-suggest-attribute=pure -Wno-suggest-attribute=const > > > > >> -Wp,-D_FORTIFY_SOURCE > > > > >> + -Wno-suggest-attribute=pure -Wno-suggest-attribute=const > > > > >> -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 > > > > >> else > > > > >> EXTRA_CFLAGS = -Wunused-command-line-argument > > > > >> endif > > > > >> diff --git a/libselinux/utils/Makefile b/libselinux/utils/Makefile > > > > >> index d06ffd66893b..64ab877015c6 100644 > > > > >> --- a/libselinux/utils/Makefile > > > > >> +++ b/libselinux/utils/Makefile > > > > >> @@ -30,7 +30,7 @@ CFLAGS ?= -O -Wall -W -Wundef -Wformat-y2k > > > > >> -Wformat-security -Winit-self -Wmissi > > > > >> -Wformat-extra-args -Wformat-zero-length -Wformat=2 > > > > >> -Wmultichar \ > > > > >> -Woverflow -Wpointer-to-int-cast -Wpragmas \ > > > > >> -Wno-missing-field-initializers -Wno-sign-compare \ > > > > >> - -Wno-format-nonliteral > > > > >> -Wframe-larger-than=$(MAX_STACK_SIZE) -Wp,-D_FORTIFY_SOURCE \ > > > > >> + -Wno-format-nonliteral > > > > >> -Wframe-larger-than=$(MAX_STACK_SIZE) -U_FORTIFY_SOURCE > > > > >> -D_FORTIFY_SOURCE=1 \ > > > > >> -fstack-protector-all --param=ssp-buffer-size=4 > > > > >> -fexceptions \ > > > > >> -fasynchronous-unwind-tables -fdiagnostics-show-option > > > > >> -funit-at-a-time \ > > > > >> -Werror -Wno-aggregate-return -Wno-redundant-decls \