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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6C973C433E2 for ; Wed, 3 Jun 2020 23:03:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2E5F32224C 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 2E5F32224C 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) Received: by kanga.kvack.org (Postfix, from userid 40) id B950028006C; Wed, 3 Jun 2020 19:03:54 -0400 (EDT) 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-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-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 _