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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 8E4B3C433FF for ; Fri, 9 Aug 2019 16:08:22 +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 4C1642086A for ; Fri, 9 Aug 2019 16:08:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="quCoc7Hf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C1642086A 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:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=MAuuc9q/31AyWSSYw7aAeA2KWKW32pD6fGFT8C7DPQs=; b=quCoc7HfvRhXvq /c6NtjFKh3Azzt4EoAcae9GOUbqJj7YCL7bifjG0a1D0bWEkCurqh9Yy82GVadZGcczDWIyEBjzCo ag5DSPI1dah763ullGUGYF0AhXLdVxexkPdlxKg50QmSHiWO6RgJF3uq7CrytaMuMIQ2kIXDLVXvq AiMj5QJ4sz6iVCl7YugZyX5vQYCGz1U4/wZk6UZNKQGu9EDkEZZWdsHQ1q11CBKStba1/jQNSwOul 85PsiK7fFbFaPB6msvyRnZoS+q7bRPwsLn3kJfwnQdEAxIyxzJy3njni+YSgEgTzJF7ILQtAqktGu GWppsQrGX4/PYPmjQ94A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hw7R5-0000PB-Es; Fri, 09 Aug 2019 16:08:11 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hw7R2-0000Oj-0Q for linux-arm-kernel@lists.infradead.org; Fri, 09 Aug 2019 16:08:09 +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 37BC415AB; Fri, 9 Aug 2019 09:08:07 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6D88D3F575; Fri, 9 Aug 2019 09:08:02 -0700 (PDT) Date: Fri, 9 Aug 2019 17:08:00 +0100 From: Catalin Marinas To: Andrey Konovalov , Will Deacon Subject: Re: [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Message-ID: <20190809160800.GC23083@arrakis.emea.arm.com> References: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190809_090808_142698_DEAF1D6D X-CRM114-Status: GOOD ( 23.42 ) 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: Mark Rutland , kvm@vger.kernel.org, Szabolcs Nagy , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Khalid Aziz , linux-kselftest@vger.kernel.org, Felix Kuehling , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, Christoph Hellwig , Jason Gunthorpe , Dmitry Vyukov , Dave Martin , Evgeniy Stepanov , linux-media@vger.kernel.org, Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Ramana Radhakrishnan , Alex Williamson , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, Kostya Serebryany , Greg Kroah-Hartman , Yishai Hadas , Dave Hansen , linux-kernel@vger.kernel.org, Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck 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 Tue, Jul 23, 2019 at 07:58:39PM +0200, Andrey Konovalov wrote: > From: Catalin Marinas > > It is not desirable to relax the ABI to allow tagged user addresses into > the kernel indiscriminately. This patch introduces a prctl() interface > for enabling or disabling the tagged ABI with a global sysctl control > for preventing applications from enabling the relaxed ABI (meant for > testing user-space prctl() return error checking without reconfiguring > the kernel). The ABI properties are inherited by threads of the same > application and fork()'ed children but cleared on execve(). A Kconfig > option allows the overall disabling of the relaxed ABI. > > The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle > MTE-specific settings like imprecise vs precise exceptions. > > Reviewed-by: Kees Cook > Signed-off-by: Catalin Marinas > Signed-off-by: Andrey Konovalov Following several discussions on the list and in private, I'm proposing the update below. I can send it as a patch on top of the current series since Will has already queued this. ---------------8<------------------------------------- >From 1b3f57ab0c2c51f8b31c19fb34d270e1f3ee57fe Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 9 Aug 2019 15:09:15 +0100 Subject: [PATCH] fixup! arm64: Introduce prctl() options to control the tagged user addresses ABI Rename abi.tagged_addr sysctl control to abi.tagged_addr_disabled, defaulting to 0. Only prevent prctl(PR_TAGGED_ADDR_ENABLE)from being called when abi.tagged_addr_disabled==1. Force unused arg* of the new prctl() to 0. Signed-off-by: Catalin Marinas --- arch/arm64/kernel/process.c | 17 ++++++++++------- kernel/sys.c | 4 ++++ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 76b7c55026aa..03689c0beb34 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -579,17 +579,22 @@ void arch_setup_new_exec(void) /* * Control the relaxed ABI allowing tagged user addresses into the kernel. */ -static unsigned int tagged_addr_prctl_allowed = 1; +static unsigned int tagged_addr_disabled; long set_tagged_addr_ctrl(unsigned long arg) { - if (!tagged_addr_prctl_allowed) - return -EINVAL; if (is_compat_task()) return -EINVAL; if (arg & ~PR_TAGGED_ADDR_ENABLE) return -EINVAL; + /* + * Do not allow the enabling of the tagged address ABI if globally + * disabled via sysctl abi.tagged_addr_disabled. + */ + if (arg & PR_TAGGED_ADDR_ENABLE && tagged_addr_disabled) + return -EINVAL; + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); return 0; @@ -597,8 +602,6 @@ long set_tagged_addr_ctrl(unsigned long arg) long get_tagged_addr_ctrl(void) { - if (!tagged_addr_prctl_allowed) - return -EINVAL; if (is_compat_task()) return -EINVAL; @@ -618,9 +621,9 @@ static int one = 1; static struct ctl_table tagged_addr_sysctl_table[] = { { - .procname = "tagged_addr", + .procname = "tagged_addr_disabled", .mode = 0644, - .data = &tagged_addr_prctl_allowed, + .data = &tagged_addr_disabled, .maxlen = sizeof(int), .proc_handler = proc_dointvec_minmax, .extra1 = &zero, diff --git a/kernel/sys.c b/kernel/sys.c index c6c4d5358bd3..ec48396b4943 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2499,9 +2499,13 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = PAC_RESET_KEYS(me, arg2); break; case PR_SET_TAGGED_ADDR_CTRL: + if (arg3 || arg4 || arg5) + return -EINVAL; error = SET_TAGGED_ADDR_CTRL(arg2); break; case PR_GET_TAGGED_ADDR_CTRL: + if (arg2 || arg3 || arg4 || arg5) + return -EINVAL; error = GET_TAGGED_ADDR_CTRL(); break; default: _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel