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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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=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 7ED3FC10F27 for ; Mon, 9 Mar 2020 10:32:56 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4C03320409 for ; Mon, 9 Mar 2020 10:32:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lXg3bXWG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C03320409 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=78fZPovFpwILSLU/cCm1eX5SHQ1g/z8Elq1YYr6C/WM=; b=lXg3bXWGJkUJHX WM2PFnucQdKjx4kX68QFkP3HCswnaTNdt4cejDlgKGHEf8ukAzNHwWHX1qPStZKL+AaPe8G0w4tND gNGDjc8iTIDeq9aOC6ejcGsLg8/I53/5LnDQs3yoiRK1Rr02baOlb/E6BS0HZ1tIrB0yvkJ+YgnfR CPw6b35IunpsiVcOEs5xgzB5u+iGtGVaX4/sK7X7bOrHMldhxZpiefYwhevL4kfNlH/bJMrxal0YH E00q2wZYak5EqMllJ7nYXx3ZFu7zUSCWcvsdiq/1haOmAie6mxqAyqBhdEIt6BmvYVz+kmff/d0N8 bj6baTotkBxgC6GT7/tg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBFiP-0007Fs-Ru; Mon, 09 Mar 2020 10:32:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBFiD-0006xj-M3 for linux-arm-kernel@lists.infradead.org; Mon, 09 Mar 2020 10:32:43 +0000 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 08E7D1FB; Mon, 9 Mar 2020 03:32:31 -0700 (PDT) Received: from [10.1.195.32] (e112269-lin.cambridge.arm.com [10.1.195.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 75E5F3F67D; Mon, 9 Mar 2020 03:32:29 -0700 (PDT) Subject: Re: [PATCH] arm64: add check_wx_pages debugfs for CHECK_WX To: Phong Tran , Catalin Marinas , "will@kernel.org" , "alexios.zavras@intel.com" , "tglx@linutronix.de" , "akpm@linux-foundation.org" , Steve Capper , Mark Rutland , "broonie@kernel.org" , "keescook@chromium.org" References: <20200307093926.27145-1-tranmanphong@gmail.com> From: Steven Price Message-ID: <34739c99-3436-e88f-769b-43c48caa8817@arm.com> Date: Mon, 9 Mar 2020 10:32:27 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200307093926.27145-1-tranmanphong@gmail.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200309_033241_806499_DAB7A929 X-CRM114-Status: GOOD ( 25.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kernel-hardening@lists.openwall.com" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/03/2020 09:39, Phong Tran wrote: > follow the suggestion from > https://github.com/KSPP/linux/issues/35 > > 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. I would suggest it may be better spelling this out a bit more, because at the moment it's a little confusing when the config option is "Warn on W+X mappings at boot", but your change makes it sound like it only happens when you do the echo. Perhaps something like: There is no runtime or memory usage effect of this option once the kernel has booted up - it's a one time check at boot, and can also be triggered at runtime by echo "1" to "check_wx_pages". > > 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 */ This is a confusing! Why have you made it dependent on CONFIG_PTDUMP_DEBUGFS? Well actually I can see why - it's because you've put the new functions in ptdump_debugfs.c which is (currently) only built when CONFIG_PTDUMP_DBEUGFS is enabled. So you need to either: a) Ensure the new code is built when CONFIG_PTDUMP_DEBUGFS isn't enabled. b) Update the Kconfig help text to say that the debugfs file for triggering a runtime W+X check is only available if CONFIG_PTDUMP_DEBUGFS is also enabled. Other than the confusion over config symbols this looks good. Thanks, Steve > 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; > +} > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel