From patchwork Fri May 8 06:43:05 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephan Mueller X-Patchwork-Id: 6362841 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: X-Original-To: patchwork-linux-crypto@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 0FE729F373 for ; Fri, 8 May 2015 06:45:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2372120108 for ; Fri, 8 May 2015 06:45:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 233D92010F for ; Fri, 8 May 2015 06:45:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751508AbbEHGoq (ORCPT ); Fri, 8 May 2015 02:44:46 -0400 Received: from mail.eperm.de ([89.247.134.16]:34728 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149AbbEHGom (ORCPT ); Fri, 8 May 2015 02:44:42 -0400 Received: from tachyon.chronox.de (mail.eperm.de [89.247.134.16]) by mail.eperm.de (Postfix) with ESMTPSA id 6193B2A0044; Fri, 8 May 2015 08:44:36 +0200 (CEST) From: Stephan Mueller To: herbert@gondor.apana.org.au Cc: pebolle@tiscali.nl, andreas.steffen@strongswan.org, tytso@mit.edu, sandyinchina@gmail.com, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: [PATCH v5 4/5] crypto: drbg - use Jitter RNG to obtain seed Date: Fri, 08 May 2015 08:43:05 +0200 Message-ID: <2293996.v8pP5xBavb@tachyon.chronox.de> User-Agent: KMail/4.14.6 (Linux/3.19.5-200.fc21.x86_64; KDE/4.14.6; x86_64; ; ) In-Reply-To: <1887272.cxqymnQQZn@tachyon.chronox.de> References: <1887272.cxqymnQQZn@tachyon.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 X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP During initialization, the DRBG now tries to allocate a handle of the Jitter RNG. If such a Jitter RNG is available during seeding, the DRBG pulls the required entropy/nonce string from get_random_bytes and concatenates it with a string of equal size from the Jitter RNG. That combined string is now the seed for the DRBG. Written differently, the initial seed of the DRBG is now: get_random_bytes(entropy/nonce) || jitterentropy (entropy/nonce) If the Jitter RNG is not available, the DRBG only seeds from get_random_bytes. CC: Andreas Steffen CC: Theodore Ts'o CC: Sandy Harris Signed-off-by: Stephan Mueller --- crypto/drbg.c | 46 ++++++++++++++++++++++++++++++++++++++++------ include/crypto/drbg.h | 1 + 2 files changed, 41 insertions(+), 6 deletions(-) diff --git a/crypto/drbg.c b/crypto/drbg.c index 693dac4..6e2b272 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -1120,10 +1120,25 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, drbg->test_data.len); pr_devel("DRBG: using test entropy\n"); } else { - pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n", - drbg->seed_buf_len); + /* Get seed from in-kernel /dev/urandom */ get_random_bytes(drbg->seed_buf, drbg->seed_buf_len); - drbg_string_fill(&data1, drbg->seed_buf, drbg->seed_buf_len); + + /* Get seed from Jitter RNG */ + if (!drbg->jent || + crypto_rng_get_bytes(drbg->jent, + drbg->seed_buf + drbg->seed_buf_len, + drbg->seed_buf_len)) { + pr_info("DRBG: could not obtain random data from Jitter RNG\n"); + drbg_string_fill(&data1, drbg->seed_buf, + drbg->seed_buf_len); + pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n", + drbg->seed_buf_len); + } else { + drbg_string_fill(&data1, drbg->seed_buf, + drbg->seed_buf_len * 2); + pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n", + drbg->seed_buf_len * 2); + } } list_add_tail(&data1.list, &seedlist); @@ -1148,7 +1163,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, * Clear the initial entropy buffer as the async call may not overwrite * that buffer for quite some time. */ - memzero_explicit(drbg->seed_buf, drbg->seed_buf_len); + memzero_explicit(drbg->seed_buf, drbg->seed_buf_len * 2); if (ret) goto out; /* @@ -1190,6 +1205,10 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg) #endif kzfree(drbg->seed_buf); drbg->seed_buf = NULL; + if (drbg->jent) { + crypto_free_rng(drbg->jent); + drbg->jent = NULL; + } } /* @@ -1265,12 +1284,27 @@ static inline int drbg_alloc_state(struct drbg_state *drbg) ret = -EFAULT; goto err; } - /* ensure we have sufficient buffer space for initial seed */ + /* + * Ensure we have sufficient buffer space for initial seed which + * consists of the seed from get_random_bytes and the Jitter RNG. + */ drbg->seed_buf_len = ((drbg->seed_buf_len + 1) / 2) * 3; - drbg->seed_buf = kzalloc(drbg->seed_buf_len, GFP_KERNEL); + drbg->seed_buf = kzalloc(drbg->seed_buf_len * 2, GFP_KERNEL); if (!drbg->seed_buf) goto err; + drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0); + if(IS_ERR(drbg->jent)) + { + pr_info("DRBG: could not allocate Jitter RNG handle for seeding\n"); + /* + * As the Jitter RNG is a module that may not be present, we + * continue with the operation and do not fully tie the DRBG + * to the Jitter RNG. + */ + drbg->jent = NULL; + } + return 0; err: diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index e4980a1..fabf102 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -122,6 +122,7 @@ struct drbg_state { struct random_work seed_work; /* asynchronous seeding support */ u8 *seed_buf; /* buffer holding the seed */ size_t seed_buf_len; + struct crypto_rng *jent; const struct drbg_state_ops *d_ops; const struct drbg_core *core; struct drbg_string test_data;