Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F948C433EF for ; Sun, 21 Nov 2021 16:50:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238543AbhKUQxM (ORCPT ); Sun, 21 Nov 2021 11:53:12 -0500 Received: from mo4-p04-ob.smtp.rzone.de ([81.169.146.177]:29147 "EHLO mo4-p04-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238079AbhKUQwz (ORCPT ); Sun, 21 Nov 2021 11:52:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1637513318; s=strato-dkim-0002; d=chronox.de; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Cc:Date: From:Subject:Sender; bh=YUtaUGvXy4RCwHEdoN+oGR/T7eofnkQwvJGOX+pp5/s=; b=BUovignxOjM0jsdtw2/OZwtcEeVLWrBTSukaBoDwwA4wkpFWM4l9qyus3Cob57YdX+ MR9Cq6z04gUUFzpxJ7ma6++vrt//RVXA0AqPUPEsgajUvFL1aKhXGaiCIi1ReuwMQuil 3xT6MPkVE5CsypJt2zkRqGXzQNWJTJFqBOno3pUH7cWg1X9Waj6iQIPsi7aX3ayW7fcu aUbxYYO0syGoPKyNUDvr57hIdGlWdM/pvpGOv1aUfyJOixlWhzCaaBWu9DneFW1eb1fC +lQqSPwTbfDcfk9QxWqYxU0GO5eQi0AiJvCgA1tn7cKrB87dCt0yckDygb/VGG+jPZ55 i8tA== Authentication-Results: strato.com; dkim=none X-RZG-AUTH: ":P2ERcEykfu11Y98lp/T7+hdri+uKZK8TKWEqNyiHySGSa9k9xmwdNnzGHXPbJvSfE+K2" X-RZG-CLASS-ID: mo00 Received: from positron.chronox.de by smtp.strato.de (RZmta 47.34.5 DYNA|AUTH) with ESMTPSA id U02dfbxALGmb3Wk (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Sun, 21 Nov 2021 17:48:37 +0100 (CET) From: Stephan =?ISO-8859-1?Q?M=FCller?= To: Tso Ted , linux-crypto@vger.kernel.org Cc: Willy Tarreau , Nicolai Stange , LKML , Arnd Bergmann , Greg Kroah-Hartman , "Eric W. Biederman" , "Alexander E. Patrakov" , "Ahmed S. Darwish" , Matthew Garrett , Vito Caputo , Andreas Dilger , Jan Kara , Ray Strode , William Jon McCann , zhangjs , Andy Lutomirski , Florian Weimer , Lennart Poettering , Peter Matthias , Marcelo Henrique Cerri , Neil Horman , Randy Dunlap , Julia Lawall , Dan Carpenter , Andy Lavr , Eric Biggers , "Jason A. Donenfeld" , Petr Tesarik , John Haxby , Alexander Lobakin , Jirka Hladky Subject: [PATCH v43 05/15] LRNG - CPU entropy source Date: Sun, 21 Nov 2021 17:42:09 +0100 Message-ID: <6686472.9J7NaK4W3v@positron.chronox.de> In-Reply-To: <2036923.9o76ZdvQCi@positron.chronox.de> References: <2036923.9o76ZdvQCi@positron.chronox.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Certain CPUs provide instructions giving access to an entropy source (e.g. RDSEED on Intel/AMD, DARN on POWER, etc.). The LRNG can utilize the entropy source to seed its DRNG from. CC: Torsten Duwe 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: Alexander Lobakin Tested-by: Alexander Lobakin Mathematical aspects Reviewed-by: "Peter, Matthias" Reviewed-by: Marcelo Henrique Cerri Reviewed-by: Roman Drahtmueller Tested-by: Marcelo Henrique Cerri Tested-by: Neil Horman Tested-by: Jirka Hladky Reviewed-by: Jirka Hladky Signed-off-by: Stephan Mueller --- drivers/char/lrng/Kconfig | 38 +++++ drivers/char/lrng/Makefile | 1 + drivers/char/lrng/lrng_es_archrandom.c | 226 +++++++++++++++++++++++++ 3 files changed, 265 insertions(+) create mode 100644 drivers/char/lrng/lrng_es_archrandom.c diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig index a9ae35d9f648..d3abdfa28493 100644 --- a/drivers/char/lrng/Kconfig +++ b/drivers/char/lrng/Kconfig @@ -215,6 +215,44 @@ config LRNG_IRQ_ENTROPY_RATE interrupt entropy source will still deliver data but without being credited with entropy. +comment "CPU Entropy Source" + +config LRNG_CPU + bool "Enable CPU Entropy Source as LRNG Seed Source" + default y + help + Current CPUs commonly contain entropy sources which can be + used to seed the LRNG. For example, the Intel RDSEED + instruction, or the POWER DARN instruction will be sourced + to seed the LRNG if this option is enabled. + + Note, if this option is enabled and the underlying CPU + does not offer such entropy source, the LRNG will automatically + detect this and ignore the hardware. + +config LRNG_CPU_FULL_ENT_MULTIPLIER + int + default 1 if !LRNG_TEST_CPU_ES_COMPRESSION + default 123 if LRNG_TEST_CPU_ES_COMPRESSION + +config LRNG_CPU_ENTROPY_RATE + int "CPU Entropy Source Entropy Rate" + depends on LRNG_CPU + range 0 256 + default 8 + help + The option defines the amount of entropy the LRNG applies to 256 + bits of data obtained from the CPU entropy source. The LRNG + enforces the limit that this value must be in the range between + 0 and 256. + + When configuring this value to 0, the CPU entropy source will + provide 256 bits of data without being credited to contain + entropy. + + Note, this option is overwritten when the option + CONFIG_RANDOM_TRUST_CPU is set. + endmenu # "Entropy Source Configuration" endif # LRNG diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile index 1e722e0967e0..1e18e2c1016b 100644 --- a/drivers/char/lrng/Makefile +++ b/drivers/char/lrng/Makefile @@ -10,3 +10,4 @@ obj-y += lrng_es_mgr.o lrng_aux.o \ obj-$(CONFIG_LRNG_IRQ) += lrng_es_irq.o obj-$(CONFIG_SYSCTL) += lrng_proc.o obj-$(CONFIG_NUMA) += lrng_numa.o +obj-$(CONFIG_LRNG_CPU) += lrng_es_archrandom.o diff --git a/drivers/char/lrng/lrng_es_archrandom.c b/drivers/char/lrng/lrng_es_archrandom.c new file mode 100644 index 000000000000..6965f9b8ae50 --- /dev/null +++ b/drivers/char/lrng/lrng_es_archrandom.c @@ -0,0 +1,226 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +/* + * LRNG Fast Entropy Source: CPU-based entropy source + * + * Copyright (C) 2016 - 2021, Stephan Mueller + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include + +#include "lrng_internal.h" + +/* + * Estimated entropy of data is a 32th of LRNG_DRNG_SECURITY_STRENGTH_BITS. + * As we have no ability to review the implementation of those noise sources, + * it is prudent to have a conservative estimate here. + */ +#define LRNG_ARCHRANDOM_DEFAULT_STRENGTH CONFIG_LRNG_CPU_ENTROPY_RATE +#define LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH LRNG_DRNG_SECURITY_STRENGTH_BITS +#ifdef CONFIG_RANDOM_TRUST_CPU +static u32 archrandom = LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH; +#else +static u32 archrandom = LRNG_ARCHRANDOM_DEFAULT_STRENGTH; +#endif +#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG +module_param(archrandom, uint, 0644); +MODULE_PARM_DESC(archrandom, "Entropy in bits of 256 data bits from CPU noise source (e.g. RDSEED)"); +#endif + +static int __init lrng_parse_trust_cpu(char *arg) +{ + int ret; + bool trust_cpu = false; + + ret = kstrtobool(arg, &trust_cpu); + if (ret) + return ret; + + if (trust_cpu) { + archrandom = LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH; + lrng_pool_add_entropy(); + } else { + archrandom = LRNG_ARCHRANDOM_DEFAULT_STRENGTH; + } + + return 0; +} +early_param("random.trust_cpu", lrng_parse_trust_cpu); + +u32 lrng_archrandom_entropylevel(u32 requested_bits) +{ + return lrng_fast_noise_entropylevel(archrandom, requested_bits); +} + +static u32 lrng_get_arch_data(u8 *outbuf, u32 requested_bits) +{ + u32 i; + + /* operate on full blocks */ + BUILD_BUG_ON(LRNG_DRNG_SECURITY_STRENGTH_BYTES % sizeof(unsigned long)); + BUILD_BUG_ON(CONFIG_LRNG_SEED_BUFFER_INIT_ADD_BITS % + sizeof(unsigned long)); + /* ensure we have aligned buffers */ + BUILD_BUG_ON(LRNG_KCAPI_ALIGN % sizeof(unsigned long)); + + for (i = 0; i < (requested_bits >> 3); + i += sizeof(unsigned long)) { + if (!arch_get_random_seed_long((unsigned long *)(outbuf + i)) && + !arch_get_random_long((unsigned long *)(outbuf + i))) { + archrandom = 0; + return 0; + } + } + + return requested_bits; +} + +static u32 inline lrng_get_arch_data_compress(u8 *outbuf, u32 requested_bits, + u32 data_multiplier) +{ + SHASH_DESC_ON_STACK(shash, NULL); + const struct lrng_crypto_cb *crypto_cb; + struct lrng_drng *drng = lrng_drng_init_instance(); + unsigned long flags; + u32 ent_bits = 0, i, partial_bits = 0, + full_bits = requested_bits * data_multiplier; + void *hash; + + /* Calculate oversampling for SP800-90C */ + if (lrng_sp80090c_compliant()) { + /* Complete amount of bits to be pulled */ + full_bits += CONFIG_LRNG_OVERSAMPLE_ES_BITS * data_multiplier; + /* Full blocks that will be pulled */ + data_multiplier = full_bits / requested_bits; + /* Partial block in bits to be pulled */ + partial_bits = full_bits - (data_multiplier * requested_bits); + } + + lrng_hash_lock(drng, &flags); + crypto_cb = drng->crypto_cb; + hash = drng->hash; + + if (crypto_cb->lrng_hash_init(shash, hash)) + goto out; + + /* Hash all data from the CPU entropy source */ + for (i = 0; i < data_multiplier; i++) { + ent_bits = lrng_get_arch_data(outbuf, requested_bits); + if (!ent_bits) + goto out; + + if (crypto_cb->lrng_hash_update(shash, outbuf, ent_bits >> 3)) + goto err; + } + + /* Hash partial block, if applicable */ + ent_bits = lrng_get_arch_data(outbuf, partial_bits); + if (ent_bits && + crypto_cb->lrng_hash_update(shash, outbuf, ent_bits >> 3)) + goto err; + + pr_debug("pulled %u bits from CPU RNG entropy source\n", full_bits); + + /* Generate the compressed data to be returned to the caller */ + ent_bits = crypto_cb->lrng_hash_digestsize(hash) << 3; + if (requested_bits < ent_bits) { + u8 digest[LRNG_MAX_DIGESTSIZE]; + + if (crypto_cb->lrng_hash_final(shash, digest)) + goto err; + + /* Truncate output data to requested size */ + memcpy(outbuf, digest, requested_bits >> 3); + memzero_explicit(digest, crypto_cb->lrng_hash_digestsize(hash)); + ent_bits = requested_bits; + } else { + if (crypto_cb->lrng_hash_final(shash, outbuf)) + goto err; + } + +out: + crypto_cb->lrng_hash_desc_zero(shash); + lrng_hash_unlock(drng, flags); + return ent_bits; + +err: + ent_bits = 0; + goto out; +} + +/* + * If CPU entropy source requires does not return full entropy, return the + * multiplier of how much data shall be sampled from it. + */ +static u32 lrng_arch_multiplier(void) +{ + static u32 data_multiplier = 0; + + if (data_multiplier > 0) { + return data_multiplier; + } else { + unsigned long v; + + if (IS_ENABLED(CONFIG_X86) && !arch_get_random_seed_long(&v)) { + /* + * Intel SPEC: pulling 512 blocks from RDRAND ensures + * one reseed making it logically equivalent to RDSEED. + */ + data_multiplier = 512; + } else if (IS_ENABLED(CONFIG_PPC)) { + /* + * PowerISA defines DARN to deliver at least 0.5 bits of + * entropy per data bit. + */ + data_multiplier = 2; + } else { + /* CPU provides full entropy */ + data_multiplier = CONFIG_LRNG_CPU_FULL_ENT_MULTIPLIER; + } + } + return data_multiplier; +} + +/* + * lrng_get_arch() - Get CPU entropy source entropy + * + * @outbuf: buffer to store entropy of size requested_bits + * + * Return: + * * > 0 on success where value provides the added entropy in bits + * * 0 if no fast source was available + */ +u32 lrng_get_arch(u8 *outbuf, u32 requested_bits) +{ + u32 ent_bits, data_multiplier = lrng_arch_multiplier(); + + if (data_multiplier <= 1) { + ent_bits = lrng_get_arch_data(outbuf, requested_bits); + } else { + ent_bits = lrng_get_arch_data_compress(outbuf, requested_bits, + data_multiplier); + } + + ent_bits = lrng_archrandom_entropylevel(ent_bits); + pr_debug("obtained %u bits of entropy from CPU RNG entropy source\n", + ent_bits); + return ent_bits; +} + +void lrng_arch_es_state(unsigned char *buf, size_t buflen) +{ + const struct lrng_drng *lrng_drng_init = lrng_drng_init_instance(); + u32 data_multiplier = lrng_arch_multiplier(); + + /* Assume the lrng_drng_init lock is taken by caller */ + snprintf(buf, buflen, + "CPU ES properties:\n" + " Hash for compressing data: %s\n" + " Data multiplier: %u\n", + (data_multiplier <= 1) ? + "N/A" : lrng_drng_init->crypto_cb->lrng_hash_name(), + data_multiplier); +} -- 2.31.1