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=-13.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 674A1C10F27 for ; Mon, 9 Mar 2020 16:51:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4832D20828 for ; Mon, 9 Mar 2020 16:51:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727236AbgCIQvu (ORCPT ); Mon, 9 Mar 2020 12:51:50 -0400 Received: from foss.arm.com ([217.140.110.172]:54596 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727132AbgCIQvu (ORCPT ); Mon, 9 Mar 2020 12:51:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9A9A11FB; Mon, 9 Mar 2020 09:51:49 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EDE713F534; Mon, 9 Mar 2020 09:51:47 -0700 (PDT) Date: Mon, 9 Mar 2020 16:51:39 +0000 From: Mark Rutland To: Kees Cook Cc: Phong Tran , catalin.marinas@arm.com, will@kernel.org, alexios.zavras@intel.com, tglx@linutronix.de, akpm@linux-foundation.org, steven.price@arm.com, steve.capper@arm.com, broonie@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [PATCH] arm64: add check_wx_pages debugfs for CHECK_WX Message-ID: <20200309165125.GA44566@lakrids.cambridge.arm.com> References: <20200307093926.27145-1-tranmanphong@gmail.com> <20200309121713.GA26309@lakrids.cambridge.arm.com> <202003090914.F6720CFF13@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202003090914.F6720CFF13@keescook> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 09, 2020 at 09:15:10AM -0700, Kees Cook wrote: > On Mon, Mar 09, 2020 at 12:17:14PM +0000, Mark Rutland wrote: > > On Sat, Mar 07, 2020 at 04:39:26PM +0700, Phong Tran wrote: > > > follow the suggestion from > > > https://github.com/KSPP/linux/issues/35 > > > > That says: > > > > | This should be implemented for all architectures > > > > ... so surely this should be in generic code, rahter than being > > arm64-specific? > > Not all architectures have implemented CONFIG_DEBUG_WX... Sure; I assumed the generic code could be gated with: #ifdef CONFIG_DEBUG_WX debug_checkwx() #endif ... or something to that effect, so that the common code could handle all the sysfs bits and ensure that part was consistent. Thanksm Mark. > > -Kees > > > > > Thanks, > > Mark. > > > > > > > > Signed-off-by: Phong Tran > > > --- > > > arch/arm64/Kconfig.debug | 3 ++- > > > arch/arm64/include/asm/ptdump.h | 2 ++ > > > arch/arm64/mm/dump.c | 1 + > > > arch/arm64/mm/ptdump_debugfs.c | 18 ++++++++++++++++++ > > > 4 files changed, 23 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug > > > index 1c906d932d6b..be552fa351e2 100644 > > > --- a/arch/arm64/Kconfig.debug > > > +++ b/arch/arm64/Kconfig.debug > > > @@ -48,7 +48,8 @@ config DEBUG_WX > > > 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. > > > + once the kernel has booted up - it's a one time check and > > > + can be checked by echo "1" to "check_wx_pages" debugfs in runtime. > > > > > > If in doubt, say "Y". > > > > > > diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h > > > index 38187f74e089..b80d6b4fc508 100644 > > > --- a/arch/arm64/include/asm/ptdump.h > > > +++ b/arch/arm64/include/asm/ptdump.h > > > @@ -24,9 +24,11 @@ struct ptdump_info { > > > void ptdump_walk(struct seq_file *s, struct ptdump_info *info); > > > #ifdef CONFIG_PTDUMP_DEBUGFS > > > void ptdump_debugfs_register(struct ptdump_info *info, const char *name); > > > +int ptdump_check_wx_init(void); > > > #else > > > static inline void ptdump_debugfs_register(struct ptdump_info *info, > > > const char *name) { } > > > +static inline int ptdump_check_wx_init(void) { return 0; } > > > #endif > > > void ptdump_check_wx(void); > > > #endif /* CONFIG_PTDUMP_CORE */ > > > diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c > > > index 860c00ec8bd3..60c99a047763 100644 > > > --- a/arch/arm64/mm/dump.c > > > +++ b/arch/arm64/mm/dump.c > > > @@ -378,6 +378,7 @@ static int ptdump_init(void) > > > #endif > > > ptdump_initialize(); > > > ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); > > > + ptdump_check_wx_init(); > > > return 0; > > > } > > > device_initcall(ptdump_init); > > > diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c > > > index 1f2eae3e988b..73cddc12c3c2 100644 > > > --- a/arch/arm64/mm/ptdump_debugfs.c > > > +++ b/arch/arm64/mm/ptdump_debugfs.c > > > @@ -16,3 +16,21 @@ void ptdump_debugfs_register(struct ptdump_info *info, const char *name) > > > { > > > debugfs_create_file(name, 0400, NULL, info, &ptdump_fops); > > > } > > > + > > > +static int check_wx_debugfs_set(void *data, u64 val) > > > +{ > > > + if (val != 1ULL) > > > + return -EINVAL; > > > + > > > + ptdump_check_wx(); > > > + > > > + return 0; > > > +} > > > + > > > +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); > > > + > > > +int ptdump_check_wx_init(void) > > > +{ > > > + return debugfs_create_file("check_wx_pages", 0200, NULL, > > > + NULL, &check_wx_fops) ? 0 : -ENOMEM; > > > +} > > > -- > > > 2.20.1 > > > > > -- > Kees Cook