From patchwork Wed Jun 3 23:03:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11586597 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0BD5992A for ; Wed, 3 Jun 2020 23:03:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CCFB12225F for ; Wed, 3 Jun 2020 23:03:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1rYW0p13" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCFB12225F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C338328008B; Wed, 3 Jun 2020 19:03:54 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id B950028006C; Wed, 3 Jun 2020 19:03:54 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A5CFD28008B; Wed, 3 Jun 2020 19:03:54 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0176.hostedemail.com [216.40.44.176]) by kanga.kvack.org (Postfix) with ESMTP id 83BBC28006C for ; Wed, 3 Jun 2020 19:03:54 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 5003E824556B for ; Wed, 3 Jun 2020 23:03:54 +0000 (UTC) X-FDA: 76889429988.22.base15_3f2111fb62039 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 24E1718038E67 for ; Wed, 3 Jun 2020 23:03:54 +0000 (UTC) X-Spam-Summary: 10,1,0,da4e8b2a1cb91891,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:355:379:800:960:967:968:973:988:989:1260:1263:1345:1359:1381:1431:1437:1534:1543:1711:1730:1747:1777:1792:1981:2194:2199:2393:2525:2559:2567:2682:2685:2693:2859:2894:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3167:3354:3865:3866:3867:3868:3870:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4250:4321:4605:5007:6119:6261:6653:6737:7576:7875:8599:9025:9545:10004:10913:11026:11257:11473:11658:11914:12043:12048:12291:12296:12297:12438:12517:12519:12555:12679:12683:12783:12986:13095:13846:14096:14181:14721:14849:21080:21220:21433:21451:21627:21889:21939:30029:30054:30070:30089,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: base15_3f2111fb62039 X-Filterd-Recvd-Size: 4636 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Wed, 3 Jun 2020 23:03:53 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7E1452225B; Wed, 3 Jun 2020 23:03:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591225433; bh=p+NC2fqfjADq0WMHDzKt4t9GrW836oGdDTsTs1NLjDY=; h=Date:From:To:Subject:In-Reply-To:From; b=1rYW0p13kx61AWBL47gd4x6prJzJsf9UKx3+uXXD0WbPs9Oqusv3kPqrKjHYU+H6p sk+JJTH0lapVNYupTFWmtqbs25/p5ykyzn02GqTRwnOONXwo4cBU+pGrS3L1TsC0bL lfVEYuxVJgkofLXbJ1wmTQdsxssEhdTxDa25EI6c= Date: Wed, 03 Jun 2020 16:03:52 -0700 From: Andrew Morton To: akpm@linux-foundation.org, bp@alien8.de, catalin.marinas@arm.com, hpa@zytor.com, linux-mm@kvack.org, mingo@redhat.com, mm-commits@vger.kernel.org, palmer@dabbelt.com, paul.walmsley@sifive.com, tglx@linutronix.de, torvalds@linux-foundation.org, will@kernel.org, zong.li@sifive.com Subject: [patch 128/131] mm: add DEBUG_WX support Message-ID: <20200603230352.5Ea0perKx%akpm@linux-foundation.org> In-Reply-To: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 24E1718038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Zong Li Subject: mm: add DEBUG_WX support Patch series "Extract DEBUG_WX to shared use". Some architectures support DEBUG_WX function, it's verbatim from each others, so extract to mm/Kconfig.debug for shared use. PPC and ARM ports don't support generic page dumper yet, so we only refine x86 and arm64 port in this patch series. For RISC-V port, the DEBUG_WX support depends on other patches which be merged already: - RISC-V page table dumper - Support strict kernel memory permissions for security This patch (of 4): Some architectures support DEBUG_WX function, it's verbatim from each others. Extract to mm/Kconfig.debug for shared use. [akpm@linux-foundation.org: reword text, per Will Deacon & Zong Li] Link: http://lkml.kernel.org/r/20200427194245.oxRJKj3fn%25akpm@linux-foundation.org [zong.li@sifive.com: remove the specific name of arm64] Link: http://lkml.kernel.org/r/3a6a92ecedc54e1d0fc941398e63d504c2cd5611.1589178399.git.zong.li@sifive.com [zong.li@sifive.com: add MMU dependency for DEBUG_WX] Link: http://lkml.kernel.org/r/4a674ac7863ff39ca91847b10e51209771f99416.1589178399.git.zong.li@sifive.com Link: http://lkml.kernel.org/r/cover.1587455584.git.zong.li@sifive.com Link: http://lkml.kernel.org/r/23980cd0f0e5d79e24a92169116407c75bcc650d.1587455584.git.zong.li@sifive.com Signed-off-by: Zong Li Suggested-by: Palmer Dabbelt Cc: Paul Walmsley Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Andrew Morton --- mm/Kconfig.debug | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) --- a/mm/Kconfig.debug~mm-add-debug_wx-support +++ a/mm/Kconfig.debug @@ -118,6 +118,38 @@ config DEBUG_RODATA_TEST ---help--- This option enables a testcase for the setting rodata read-only. +config ARCH_HAS_DEBUG_WX + bool + +config DEBUG_WX + bool "Warn on W+X mappings at boot" + depends on ARCH_HAS_DEBUG_WX + depends on MMU + select PTDUMP_CORE + help + Generate a warning if any W+X mappings are found at boot. + + This is useful for discovering cases where the kernel is leaving W+X + mappings after applying NX, as such mappings are a security risk. + + Look for a message in dmesg output like this: + + /mm: Checked W+X mappings: passed, no W+X pages found. + + or like this, if the check failed: + + /mm: Checked W+X mappings: failed, W+X pages found. + + Note that even if the check fails, your kernel is possibly + still fine, as W+X mappings are not a security hole in + themselves, what they do is that they make the exploitation + of other unfixed kernel bugs easier. + + There is no runtime or memory usage effect of this option + once the kernel has booted up - it's a one time check. + + If in doubt, say "Y". + config GENERIC_PTDUMP bool