From patchwork Fri May 3 15:46:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kashyap Chamarthy X-Patchwork-Id: 10928945 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 91C0C1398 for ; Fri, 3 May 2019 15:48:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 80ACC28660 for ; Fri, 3 May 2019 15:48:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7414C28668; Fri, 3 May 2019 15:48:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 65BCC28660 for ; Fri, 3 May 2019 15:48:51 +0000 (UTC) Received: from localhost ([127.0.0.1]:42492 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hMaQc-0000wm-I2 for patchwork-qemu-devel@patchwork.kernel.org; Fri, 03 May 2019 11:48:50 -0400 Received: from eggs.gnu.org ([209.51.188.92]:35933) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hMaOQ-0007qb-IC for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hMaOO-0000SE-Id for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33192) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hMaOM-0000Q5-IP for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:30 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7EE7A3082A28; Fri, 3 May 2019 15:46:28 +0000 (UTC) Received: from paraplu.redhat.com (ovpn-116-130.ams2.redhat.com [10.36.116.130]) by smtp.corp.redhat.com (Postfix) with ESMTP id 58CBD2C167; Fri, 3 May 2019 15:46:25 +0000 (UTC) From: Kashyap Chamarthy To: qemu-devel@nongnu.org Date: Fri, 3 May 2019 17:46:13 +0200 Message-Id: <20190503154613.4192-2-kchamart@redhat.com> In-Reply-To: <20190503154613.4192-1-kchamart@redhat.com> References: <20190503154613.4192-1-kchamart@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 03 May 2019 15:46:28 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH] VirtIO-RNG: Update default entropy source to `/dev/urandom` X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rjones@redhat.com, Kashyap Chamarthy , armbru@redhat.com, amit@kernel.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP When QEMU exposes a VirtIO-RNG device to the guest, that device needs a source of entropy, and that source needs to be "non-blocking", like `/dev/urandom`. However, currently QEMU defaults to the problematic `/dev/random`, which is "blocking" (as in, it waits until sufficient entropy is available). So change the entropy source to the recommended `/dev/urandom`. Related discussion in these[1][2] past threads. [1] https://lists.nongnu.org/archive/html/qemu-devel/2018-06/msg08335.html -- "RNG: Any reason QEMU doesn't default to `/dev/urandom`?" [2] https://lists.nongnu.org/archive/html/qemu-devel/2018-09/msg02724.html -- "[RFC] Virtio RNG: Consider changing the default entropy source to /dev/urandom" Signed-off-by: Kashyap Chamarthy Reviewed-by: Daniel P. Berrangé Reviewed-by: Richard W.M. Jones --- backends/rng-random.c | 2 +- qemu-options.hx | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/backends/rng-random.c b/backends/rng-random.c index e2a49b0571..eff36ef140 100644 --- a/backends/rng-random.c +++ b/backends/rng-random.c @@ -112,7 +112,7 @@ static void rng_random_init(Object *obj) rng_random_set_filename, NULL); - s->filename = g_strdup("/dev/random"); + s->filename = g_strdup("/dev/urandom"); s->fd = -1; } diff --git a/qemu-options.hx b/qemu-options.hx index 51802cbb26..a525609149 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4276,7 +4276,7 @@ Creates a random number generator backend which obtains entropy from a device on the host. The @option{id} parameter is a unique ID that will be used to reference this entropy backend from the @option{virtio-rng} device. The @option{filename} parameter specifies which file to obtain -entropy from and if omitted defaults to @option{/dev/random}. +entropy from and if omitted defaults to @option{/dev/urandom}. @item -object rng-egd,id=@var{id},chardev=@var{chardevid}