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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 EB411C2D0DB for ; Tue, 28 Jan 2020 22:50:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B60E52465B for ; Tue, 28 Jan 2020 22:50:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="T1hFsGEO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726401AbgA1WuD (ORCPT ); Tue, 28 Jan 2020 17:50:03 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:36828 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbgA1WuD (ORCPT ); Tue, 28 Jan 2020 17:50:03 -0500 Received: by mail-pg1-f196.google.com with SMTP id k3so7788095pgc.3 for ; Tue, 28 Jan 2020 14:50:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=eHEMtu7LgfkFmyO7oGGN1Lq9IQ3mukp2v1f/r5o0L0s=; b=T1hFsGEO0/ylAav9HFUtgqeRhLCk+8mN4axKzOMQw6onWhdziR92MjVxq99AAlFqvU kku1dM+53W1OlgPVvAdZpJUQQFRFZXSDYoFSRxG+GgXnjw7uLYw9w3Uwi+5GnyvWh7Zr AS8uPHr3/+DROwe5Czh3qwOMmnX6Zh6aNF314= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=eHEMtu7LgfkFmyO7oGGN1Lq9IQ3mukp2v1f/r5o0L0s=; b=ncI5bsomA9TmXzkJbTvOx+DImXrMl0oc3SQHebPyYw0bnyIBvAzTVbBes+irpm+ejc kUZs9wQ7uJ1lxY+1McBWShDI9QRcKNYr4LPdiqrVO8SPvCIJrUk0/FgB+FWjIKlu/l9X b4+mkmiy/pPSrgSfcgLJVI7YNI8eV9SC0urqv5mr2HUCXUsk4Pwngx8KM7AmkMUZ5Fts aVOXdkksMp7LnHObBoqyTC0+qlZRe8o9kYGaaIhIH9LwzVUUlON/h7G3I4MDvfl99ym8 HkmiLCHU+1EojjSIiUwYIUjQczhmJGnCdPwcX2+i1jpWzNOiAUvlKMZZ5ac1c8y/aHx9 uAbQ== X-Gm-Message-State: APjAAAWvefbQMDMd/qVfZRNygiO7Bpm392hkL/XRGWFwWkzsxHvlwShv ugLikM6gZAYQyrDHpqTbQquMmw== X-Google-Smtp-Source: APXvYqx9wzHAeZmTEPl0AGnf9TAiBUX0F1ZcpzaNR4O6MA9xWbzMW0w2pC5Y4TVfo8+2jVMqh5iIHw== X-Received: by 2002:a65:5786:: with SMTP id b6mr27614437pgr.316.1580251802779; Tue, 28 Jan 2020 14:50:02 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id s23sm2178658pjq.17.2020.01.28.14.50.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jan 2020 14:50:02 -0800 (PST) Date: Tue, 28 Jan 2020 14:50:00 -0800 From: Kees Cook To: Sami Tolvanen Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , james.morse@arm.com, Dave Martin , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 04/11] scs: disable when function graph tracing is enabled Message-ID: <202001281449.FB1671805E@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20200128184934.77625-1-samitolvanen@google.com> <20200128184934.77625-5-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200128184934.77625-5-samitolvanen@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 28, 2020 at 10:49:27AM -0800, Sami Tolvanen wrote: > The graph tracer hooks returns by modifying frame records on the > (regular) stack, but with SCS the return address is taken from the > shadow stack, and the value in the frame record has no effect. As we > don't currently have a mechanism to determine the corresponding slot > on the shadow stack (and to pass this through the ftrace > infrastructure), for now let's disable SCS when the graph tracer is > enabled. > > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -Kees > --- > arch/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 1b16aa9a3fe5..0d746373c52e 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -530,6 +530,7 @@ config ARCH_SUPPORTS_SHADOW_CALL_STACK > > config SHADOW_CALL_STACK > bool "Clang Shadow Call Stack" > + depends on !FUNCTION_GRAPH_TRACER > depends on ARCH_SUPPORTS_SHADOW_CALL_STACK > help > This option enables Clang's Shadow Call Stack, which uses a > -- > 2.25.0.341.g760bfbb309-goog > -- Kees Cook