From patchwork Thu Jan 9 08:34:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stephan Mueller X-Patchwork-Id: 198265 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=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham 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 B9792C32771 for ; Thu, 9 Jan 2020 08:50:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 101A02067D for ; Thu, 9 Jan 2020 08:50:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=chronox.de header.i=@chronox.de header.b="HpXk8YEM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728613AbgAIIuG (ORCPT ); Thu, 9 Jan 2020 03:50:06 -0500 Received: from mo4-p03-ob.smtp.rzone.de ([85.215.255.104]:17998 "EHLO mo4-p03-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728538AbgAIIuG (ORCPT ); Thu, 9 Jan 2020 03:50:06 -0500 X-Greylist: delayed 584 seconds by postgrey-1.27 at vger.kernel.org; Thu, 09 Jan 2020 03:50:05 EST DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1578559804; s=strato-dkim-0002; d=chronox.de; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=D2GTR+D90qW/1Or09RXEMkRO1nYpoUvd+MsC5jnvAZA=; b=HpXk8YEM7tKUeHUzMXSw2YLasU+i++99u5t6MjDovtX4KJ1WFF+B71igRAKKDpVg45 Eg6K+5fnRtML9UDVIPyvRN5ingO77aqUWNgR808QcFz/50fu0nbHjJAaWcRFvYrVkSX0 JkQODO0MbMoBHDV7L0V5d3Qy3J6zv1dq/U1Sq26l3GKVkvFUdwkO1lZ+T7DMxd5KZ6hN rwrrNtEF/IrukZw7j5xddzZo+atRNfrMxxbF3HUWRmBOHTetdvs/iYyJQJRym+7b/Eax mYQbfqTG/tM17DGkzNH2aXTvzJKhzfXQpWh9AQtxnJLdSMj1ABS73LQZLqo6+g8x775g fr9A== X-RZG-AUTH: ":P2ERcEykfu11Y98lp/T7+hdri+uKZK8TKWEqNyiHySGSa9k9xmwdNnzGHXPZJPScHivh" X-RZG-CLASS-ID: mo00 Received: from positron.chronox.de by smtp.strato.de (RZmta 46.1.4 DYNA|AUTH) with ESMTPSA id u04585w098c42Zh (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Thu, 9 Jan 2020 09:38:04 +0100 (CET) From: Stephan =?iso-8859-1?q?M=FCller?= To: Arnd Bergmann Cc: Greg Kroah-Hartman , linux-crypto@vger.kernel.org, LKML , linux-api@vger.kernel.org, "Eric W. Biederman" , "Alexander E. Patrakov" , "Ahmed S. Darwish" , "Theodore Y. Ts'o" , Willy Tarreau , Matthew Garrett , Vito Caputo , Andreas Dilger , Jan Kara , Ray Strode , William Jon McCann , zhangjs , Andy Lutomirski , Florian Weimer , Lennart Poettering , Nicolai Stange , "Peter, Matthias" , Marcelo Henrique Cerri , Roman Drahtmueller , Neil Horman , Randy Dunlap , Julia Lawall Subject: [PATCH v27 09/12] LRNG - add Jitter RNG fast noise source Date: Thu, 09 Jan 2020 09:34:15 +0100 Message-ID: <6341883.UacF4FzDma@positron.chronox.de> In-Reply-To: <2641155.iNH938UiKq@positron.chronox.de> References: <6157374.ptSnyUpaCn@positron.chronox.de> <2722222.P16TYeLAVu@positron.chronox.de> <2641155.iNH938UiKq@positron.chronox.de> MIME-Version: 1.0 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The Jitter RNG fast noise source implemented as part of the kernel crypto API is queried for 256 bits of entropy at the time the seed buffer managed by the LRNG is about to be filled. CC: "Eric W. Biederman" CC: "Alexander E. Patrakov" CC: "Ahmed S. Darwish" CC: "Theodore Y. Ts'o" CC: Willy Tarreau CC: Matthew Garrett CC: Vito Caputo CC: Andreas Dilger CC: Jan Kara CC: Ray Strode CC: William Jon McCann CC: zhangjs CC: Andy Lutomirski CC: Florian Weimer CC: Lennart Poettering CC: Nicolai Stange Reviewed-by: Marcelo Henrique Cerri Reviewed-by: Roman Drahtmueller Tested-by: Roman Drahtmüller Tested-by: Marcelo Henrique Cerri Tested-by: Neil Horman Signed-off-by: Stephan Mueller --- drivers/char/lrng/Kconfig | 11 +++++ drivers/char/lrng/Makefile | 1 + drivers/char/lrng/lrng_jent.c | 87 +++++++++++++++++++++++++++++++++++ 3 files changed, 99 insertions(+) create mode 100644 drivers/char/lrng/lrng_jent.c diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig index 0d070a3897dd..10b7cbdb8c8e 100644 --- a/drivers/char/lrng/Kconfig +++ b/drivers/char/lrng/Kconfig @@ -92,4 +92,15 @@ config LRNG_KCAPI provided by the selected kernel crypto API RNG. endif # LRNG_DRNG_SWITCH +config LRNG_JENT + bool "Enable Jitter RNG as LRNG Seed Source" + select CRYPTO_JITTERENTROPY + help + The Linux RNG may use the Jitter RNG as noise source. Enabling + this option enables the use of the Jitter RNG. Its default + entropy level is 16 bits of entropy per 256 data bits delivered + by the Jitter RNG. This entropy level can be changed at boot + time or at runtime with the lrng_base.jitterrng configuration + variable. + endif # LRNG diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile index 94b2dfb2dfdb..4f5b6f38f0c4 100644 --- a/drivers/char/lrng/Makefile +++ b/drivers/char/lrng/Makefile @@ -13,3 +13,4 @@ obj-$(CONFIG_SYSCTL) += lrng_proc.o obj-$(CONFIG_LRNG_DRNG_SWITCH) += lrng_switch.o obj-$(CONFIG_LRNG_DRBG) += lrng_drbg.o obj-$(CONFIG_LRNG_KCAPI) += lrng_kcapi.o +obj-$(CONFIG_LRNG_JENT) += lrng_jent.o diff --git a/drivers/char/lrng/lrng_jent.c b/drivers/char/lrng/lrng_jent.c new file mode 100644 index 000000000000..97c0d192e9c8 --- /dev/null +++ b/drivers/char/lrng/lrng_jent.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +/* + * LRNG Fast Noise Source: Jitter RNG + * + * Copyright (C) 2016 - 2020, Stephan Mueller + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include + +#include "lrng_internal.h" + +/* + * Estimated entropy of data is a 16th of LRNG_DRNG_SECURITY_STRENGTH_BITS. + * Albeit a full entropy assessment is provided for the noise source indicating + * that it provides high entropy rates and considering that it deactivates + * when it detects insufficient hardware, the chosen under estimation of + * entropy is considered to be acceptable to all reviewers. + */ +static u32 jitterrng = LRNG_DRNG_SECURITY_STRENGTH_BITS>>4; +module_param(jitterrng, uint, 0644); +MODULE_PARM_DESC(jitterrng, "Entropy in bits of 256 data bits from Jitter " + "RNG noise source"); + +/** + * Get Jitter RNG entropy + * + * @outbuf buffer to store entropy + * @outbuflen length of buffer + * @return > 0 on success where value provides the added entropy in bits + * 0 if no fast source was available + */ +static struct rand_data *lrng_jent_state; + +u32 lrng_get_jent(u8 *outbuf, unsigned int outbuflen) +{ + int ret; + u32 ent_bits = jitterrng; + unsigned long flags; + static DEFINE_SPINLOCK(lrng_jent_lock); + static int lrng_jent_initialized = 0; + + spin_lock_irqsave(&lrng_jent_lock, flags); + + if (!ent_bits || (lrng_jent_initialized == -1)) { + spin_unlock_irqrestore(&lrng_jent_lock, flags); + return 0; + } + + if (!lrng_jent_initialized) { + lrng_jent_state = jent_lrng_entropy_collector(); + if (!lrng_jent_state) { + jitterrng = 0; + lrng_jent_initialized = -1; + spin_unlock_irqrestore(&lrng_jent_lock, flags); + pr_info("Jitter RNG unusable on current system\n"); + return 0; + } + lrng_jent_initialized = 1; + pr_debug("Jitter RNG working on current system\n"); + } + ret = jent_read_entropy(lrng_jent_state, outbuf, outbuflen); + spin_unlock_irqrestore(&lrng_jent_lock, flags); + + if (ret) { + pr_debug("Jitter RNG failed with %d\n", ret); + return 0; + } + + /* Obtain entropy statement */ + if (outbuflen != LRNG_DRNG_SECURITY_STRENGTH_BYTES) + ent_bits = (ent_bits * outbuflen<<3) / + LRNG_DRNG_SECURITY_STRENGTH_BITS; + /* Cap entropy to buffer size in bits */ + ent_bits = min_t(u32, ent_bits, outbuflen<<3); + pr_debug("obtained %u bits of entropy from Jitter RNG noise source\n", + ent_bits); + + return ent_bits; +} + +u32 lrng_jent_entropylevel(void) +{ + return min_t(u32, jitterrng, LRNG_DRNG_SECURITY_STRENGTH_BITS); +}