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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 7BDDBC3A59E for ; Wed, 21 Aug 2019 16:22:01 +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 4CD4722CE3 for ; Wed, 21 Aug 2019 16:22:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RY8xFz2c" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4CD4722CE3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mit.edu 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=Im/lcDU1zpS4iJ8Nx15l3eM1L+D59K7ShHw+/Rbldu0=; b=RY8xFz2c0WdRWB RuJStvpogOCX8+3uRTgSjNrBYlxMM8YwRBnYprjsq5PUrYvn0a82TVLN9UDQfe9moUC6UefsWUJkq RBAC1iSeen2/5fHE9SUMvpHOEsOodIPPIUtE1KFIb7wNW0iusmAetGRZISGHYFyj/jw7XPM9p1ldU g9HUmhCFDPy0bnBrWwnLmNPaja7pYcXX9miUA7UtRzVpbk2k+2y7K+RUrcaEvn4hVohGutIPHknJv o3wY1d1uAnMml5HQ9auu2W7kncXTTc0P0f276n0XIzbLJEPnYoBrlVRv/lqftSF6fs+A/sH2S8/vi Uydk7FxxGeWgDuMcxyeA==; 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 1i0TN2-0004cX-Nq; Wed, 21 Aug 2019 16:22:00 +0000 Received: from outgoing-auth-1.mit.edu ([18.9.28.11] helo=outgoing.mit.edu) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i0TMz-0004cE-LL for linux-arm-kernel@lists.infradead.org; Wed, 21 Aug 2019 16:21:59 +0000 Received: from callcc.thunk.org (75-104-87-59.mobility.exede.net [75.104.87.59] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x7LGLQaP017370 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 21 Aug 2019 12:21:33 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 2CA8742049E; Wed, 21 Aug 2019 12:21:26 -0400 (EDT) Date: Wed, 21 Aug 2019 12:21:26 -0400 From: "Theodore Y. Ts'o" To: Ard Biesheuvel Subject: Re: [PATCH v8 2/3] fdt: add support for rng-seed Message-ID: <20190821162126.GA2713@mit.edu> Mail-Followup-To: "Theodore Y. Ts'o" , Ard Biesheuvel , Hsin-Yi Wang , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , Rob Herring , Devicetree List , lkml , Frank Rowand , Catalin Marinas , Will Deacon , Andrew Morton , Mike Rapoport , Miles Chen , James Morse , Andrew Murray , Mark Rutland , Jun Yao , Yu Zhao , Robin Murphy , Laura Abbott , Stephen Boyd , Kees Cook References: <20190819071602.139014-1-hsinyi@chromium.org> <20190819071602.139014-3-hsinyi@chromium.org> <20190819181349.GE10349@mit.edu> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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-20190821_092157_933991_69AB0D4F X-CRM114-Status: GOOD ( 12.58 ) 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 , Devicetree List , Yu Zhao , Kees Cook , Catalin Marinas , Stephen Boyd , Will Deacon , lkml , Mike Rapoport , Jun Yao , Miles Chen , Rob Herring , James Morse , Hsin-Yi Wang , Andrew Murray , Andrew Morton , Laura Abbott , Frank Rowand , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , Robin Murphy 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 Wed, Aug 21, 2019 at 09:39:28AM +0300, Ard Biesheuvel wrote: > > Whether to trust the firmware provided entropy is a policy decision, > and typically, we try to avoid dictating policy in the kernel, and > instead, we try to provide a sane default but give the user control > over it. > > So in this case, we should probably introduce > add_firmware_randomness() with a Kconfig/cmdline option pair to decide > whether it should be trusted or not (or reuse the one we have for > trusting RDRAND etc) I'd call it add_bootloader_randomness(), since we are trusting the *bootloader*; it's the bootloader which is vouching for the security / validity of the passed-in entropy. Furthermore, the bootloader on some architectures might be fetching directly from some secure element. And for that reason, I'd use a different Kconfig/cmdline option pair than the one used for trusting CPU-provided randomness. - Ted _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel