From nobody Thu May 16 01:42:57 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1556898500; cv=none; d=zoho.com; s=zohoarc; b=iydBgtxSOg1mbobCjaHOwKC1xZavQBQfGl7VdzgVxwGtnQGWQz/V5cOsUvCA8CHmNuwYAPgjkAqPCF+KVEXeX3AdUaKOtyk/q09kQXWVsIyt7XHQL1p2O+LseFBGIgUGklR8H5e2Q6jNYaJp6rq2/sO7oDFjaeciQGAtBLDk8MA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1556898500; h=Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:Sender:Subject:To:ARC-Authentication-Results; bh=YE4rsAbJdflyWLJcrSbWRK588j+mfLIR+cbe8+ivaE4=; b=PQMCui/7vgAFMp3zbHhqqgfcbE65UoQjZFylXJWjLT3/DSsN7Om30vQf/WaOntx44o6NxBQzDmIakUyrawqFm2BnRK9Givjp7Sx9kl9Jc/+wI0J8ae1n49H9vJe7wn3xWnhcaSLA9yWUFChyyj7VPdTSjj9lTvKfPW7S3hfDOiU= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1556898500655977.573433670004; Fri, 3 May 2019 08:48:20 -0700 (PDT) Received: from localhost ([127.0.0.1]:42482 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hMaQ5-0000E2-M2 for importer@patchew.org; Fri, 03 May 2019 11:48:17 -0400 Received: from eggs.gnu.org ([209.51.188.92]:35902) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hMaOI-0007kd-RX for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hMaOG-0000Nk-LX for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35000) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hMaOG-0000Lo-0H for qemu-devel@nongnu.org; Fri, 03 May 2019 11:46:24 -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 73D22C00735C; Fri, 3 May 2019 15:46:22 +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 79C3550C55; Fri, 3 May 2019 15:46:19 +0000 (UTC) From: Kashyap Chamarthy To: qemu-devel@nongnu.org Date: Fri, 3 May 2019 17:46:12 +0200 Message-Id: <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 [10.5.110.32]); Fri, 03 May 2019 15:46:22 +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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- 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 e2a49b0571d79eab335d5a74841d92c50a727b6a..eff36ef14084bccaad1eabe952e= 2cf6ffa9a2529 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); =20 - s->filename =3D g_strdup("/dev/random"); + s->filename =3D g_strdup("/dev/urandom"); s->fd =3D -1; } =20 diff --git a/qemu-options.hx b/qemu-options.hx index 51802cbb266a208d70989c4f0ab3317a76edc1ea..a525609149e4d0e4bb60959f029= a1a16eb36900d 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4276,7 +4276,7 @@ Creates a random number generator backend which obtai= ns 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}. =20 @item -object rng-egd,id=3D@var{id},chardev=3D@var{chardevid} =20 --=20 2.17.2