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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 CA3BCC47096 for ; Thu, 3 Jun 2021 21:33:28 +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 9000B611C9 for ; Thu, 3 Jun 2021 21:33:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9000B611C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:Cc:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=pSwvSNW8AQTDUKzVAU9mYPBeA3Nwsi5tSxp6DZAJP4Y=; b=aAgFSf/lU7C8F4 EnqR4kZvYaFc4VLh9jGLPs3mZHHk9qO8OYxblZhWa+BmXIySOwaL2W2zL+QONzmxV/pmFWvDjAlEM CLghrv2d2e5El9XR9XAfJHDprHpKmMNoyGRpMDzgx2aPnHWSOduv6NBO1LsvuzX6y6OqMiHPvw/z5 5XvbcQVqf94y6MDT/ZzXRYYogAL4MY0vTNuMfhpjyZfYZ4vGrSif8ukuz3oVLDwSmICm8oPD2urFK go4yFcysBZTzUK4pqo1OZnAFyfKnyPAbqKAGrkZ40FRb9HZbo+3S2OSmdUhHGZHk6esVggu4YMVRl r7NjM0AngSo4//vLL+GQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1louwM-00Addl-NV; Thu, 03 Jun 2021 21:31:46 +0000 Received: from gate.crashing.org ([63.228.1.57]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1louwH-00Adcu-Hq for linux-arm-kernel@lists.infradead.org; Thu, 03 Jun 2021 21:31:44 +0000 Received: from ip6-localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 153LUUHN009553; Thu, 3 Jun 2021 16:30:31 -0500 Message-ID: <9ca71c91bfc27f436bd9c04d5cd528b66870e31e.camel@kernel.crashing.org> Subject: Re: RNDR/SS vs. SMCCC From: Benjamin Herrenschmidt To: Ard Biesheuvel Cc: Andre Przywara , Mark Brown , Will Deacon , "Saidi, Ali" , Linux ARM Date: Fri, 04 Jun 2021 07:30:30 +1000 In-Reply-To: References: <7d5697f3994fc1f9cf39d332525269056e3649b3.camel@kernel.crashing.org> <0339748b54e2faeddeec8d50e32a6c6ff4e8b3b7.camel@kernel.crashing.org> <20210531020235.6e4ea946@slackpad.fritz.box> <2ae9253c6f5753c13a7ed755ab0c67316c06d9b0.camel@kernel.crashing.org> <20210603011922.1d0e9249@slackpad.fritz.box> <03af6cf4f263f9de4b7dbcf16e8a1c4962347191.camel@kernel.crashing.org> User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210603_143141_884099_F56F85FA X-CRM114-Status: GOOD ( 17.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2021-06-03 at 09:10 +0200, Ard Biesheuvel wrote: > > True. However, the way things are currently set up, the hwrng is used > both either internally (if the entropy estimate is high enough) or > via rngd in user space to read from /dev/hwrng and write it back to > /dev/random. This is kind of pointless in this case, although not > harmful per se Right. For hwrngd, we could add a flag per "source" to indicate not to bother if we cared enough. For rngd in userspace, not much to do other than deprecate that thing with newer kernels :-) > > > I would be interested to hear opinions on this. > > The issue is with things like FIPS certification (and other such > > horrors) where I believe /dev/random is much harder to deal with > > since > > it mixes multiple entropy sources. > > > /dev/random is not an entropy source but a random number generator. I > agree with your characterization of FIPS in the general case, but the > /dev/random kludge we have is not pretty either :-) True :) > > Note that NIST SP800-90A/B compliance has similar requirements, i.e., > if user space wants to seed its own DRBG in user space and comply > with these specs, it needs a compliant entropy source as well. > However, health tests on the entropy source are also mandated, and it > is not clear to me how that would fit into the SMCCC + /dev/hwrng > > arrangement. Yes I'm not sure either. But having /dev/hwrng I think won't hurt either way. Cheers, Ben. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel