From patchwork Mon Jul 17 22:05:11 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 789742 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3xBHQz3Qb2z9t2J for ; Tue, 18 Jul 2017 08:05:15 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.b="LNPuaAg2"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751342AbdGQWFN (ORCPT ); Mon, 17 Jul 2017 18:05:13 -0400 Received: from mail-pg0-f41.google.com ([74.125.83.41]:36208 "EHLO mail-pg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336AbdGQWFN (ORCPT ); Mon, 17 Jul 2017 18:05:13 -0400 Received: by mail-pg0-f41.google.com with SMTP id u5so1328525pgq.3 for ; Mon, 17 Jul 2017 15:05:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=NLDaTbNXN3UMjApc3Y3W9YxekjIx+vWyk0Fmpx28GI4=; b=LNPuaAg2MYrK+aIvZOQVIdbXLfzbBFvR2NJWP4X2ZCssNPnUgvrHzXJ4oPwhoZNsb9 TExmZJPULAdc0AVtXdHWxKVHxtfrs8bAZfQm0Llu/50b34fHWpTMWvh6UJrnZ2vw7NAs 65mD1FmLUrPVBjY9+noqiRUaRIq/ULE4/23A8= 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:mime-version :content-disposition; bh=NLDaTbNXN3UMjApc3Y3W9YxekjIx+vWyk0Fmpx28GI4=; b=bspmwXpuXTP78sxF8OwvMF8fpJCnAtJ0olclM7U3eSkPgEVsBatiPIxpGTEfqjcyDS pRuBlrLfzZj1m96KeV/FlIZPrJqp6ZJyPc3Z6Wz445t2VK8Sv5z/yj+GDd5t+ADnV9mj RCnoUjcipenzny5b9FohHCQzkRRWTFipTBfWG9SZJpvNoRaAM+QbJYOA9i76Fnf0IqYN 1Hi4zxfe4o65oGxYvU29V7Iv2pDF5RblTUITMEAw7B3QrXkYLZ6cJykP72fkT1vRPqW0 GjAf02I8j/wVOiij1qHla2Kdqb7n8TAABcQtnUL+2pfoqmQNV0yMHI0ZxRC+ba7rx/4m TTXQ== X-Gm-Message-State: AIVw112QXt1ncls+AtSJN6OUFFt3doKtA/GqXetmdL06KB2dsrZm5fin OxqjIKosPnJ7rJhm X-Received: by 10.98.33.148 with SMTP id o20mr3406091pfj.89.1500329112536; Mon, 17 Jul 2017 15:05:12 -0700 (PDT) Received: from www.outflux.net (173-164-112-133-Oregon.hfc.comcastbusiness.net. [173.164.112.133]) by smtp.gmail.com with ESMTPSA id q3sm462240pfk.8.2017.07.17.15.05.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jul 2017 15:05:11 -0700 (PDT) Date: Mon, 17 Jul 2017 15:05:11 -0700 From: Kees Cook To: Rob Herring Cc: Ard Biesheuvel , Mark Rutland , Will Deacon , AKASHI Takahiro , Catalin Marinas , Frank Rowand , James Morse , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 RESEND] dt-bindings: chosen: document kaslr-seed property Message-ID: <20170717220511.GA140556@beast> MIME-Version: 1.0 Content-Disposition: inline Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Document the /chosen/kaslr-seed property (and its interaction with the EFI_RNG_PROTOCOL API). Thanks to Ard for clarifications. Signed-off-by: Kees Cook Acked-by: Ard Biesheuvel Acked-by: Mark Rutland Acked-by: Will Deacon --- v2: - improved the language a bit based on Ard's notes - added Acks. - (resent to include lists) --- Documentation/devicetree/bindings/chosen.txt | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt index dee3f5d9df26..e3b13ea7d2ae 100644 --- a/Documentation/devicetree/bindings/chosen.txt +++ b/Documentation/devicetree/bindings/chosen.txt @@ -5,9 +5,31 @@ The chosen node does not represent a real device, but serves as a place for passing data between firmware and the operating system, like boot arguments. Data in the chosen node does not represent the hardware. +The following properties are recognized: -stdout-path property --------------------- + +kaslr-seed +----------- + +This property is used when booting with CONFIG_RANDOMIZE_BASE as the +entropy used to randomize the kernel image base address location. Since +it is used directly, this value is intended only for KASLR, and should +not be used for other purposes (as it may leak information about KASLR +offsets). It is parsed as a u64 value, e.g. + +/ { + chosen { + kaslr-seed = <0xfeedbeef 0xc0def00d>; + }; +}; + +Note that if this property is set from UEFI (or a bootloader in EFI +mode) when EFI_RNG_PROTOCOL is supported, it will be overwritten by +the Linux EFI stub (which will populate the property itself, using +EFI_RNG_PROTOCOL). + +stdout-path +----------- Device trees may specify the device to be used for boot console output with a stdout-path property under /chosen, as described in the Devicetree