From patchwork Mon Nov 15 14:18:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Nicolai Stange X-Patchwork-Id: 12619571 X-Patchwork-Delegate: herbert@gondor.apana.org.au 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE057C433FE for ; Mon, 15 Nov 2021 14:18:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA76761B54 for ; Mon, 15 Nov 2021 14:18:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231623AbhKOOVi (ORCPT ); Mon, 15 Nov 2021 09:21:38 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:53290 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231491AbhKOOVg (ORCPT ); Mon, 15 Nov 2021 09:21:36 -0500 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 6BCE2218A9; Mon, 15 Nov 2021 14:18:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1636985920; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5IBbslE/oPZTVzl0ADEJvMszbGx/M29SMnXhxo3GSkY=; b=1oqLrfuK3l1C8qlUsWayOd1sNuLRrgq8A8B6ldWRt+hyV+WmhR0Le1swh0OJiaBZ+UdAuk TvwJ0eHf+qbq/9SsuFtZFXe5vQsJAI87A3Hn2ppXX6W3L/JTjN6T+39FWcN4qEywlndrtg 92/8zkbW32eFTCMNxSKfyJ6+y77tH+M= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1636985920; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5IBbslE/oPZTVzl0ADEJvMszbGx/M29SMnXhxo3GSkY=; b=1JkmHmUmlRaVcx7G3/yX6URAOakAGfG6uDoQqU8DMiKZp5kKi4mMsOoNa5G2qnKsiaWdHk Z+nrLSH2cy8v8ADQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 55EE813476; Mon, 15 Nov 2021 14:18:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Ch6eE0BskmGNHwAAMHmgww (envelope-from ); Mon, 15 Nov 2021 14:18:40 +0000 From: Nicolai Stange To: =?utf-8?q?Stephan_M=C3=BCller?= , Herbert Xu , "David S. Miller" Cc: Torsten Duwe , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Nicolai Stange Subject: [PATCH v2 2/6] crypto: DRBG - track whether DRBG was seeded with !rng_is_initialized() Date: Mon, 15 Nov 2021 15:18:05 +0100 Message-Id: <20211115141809.11420-3-nstange@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20211115141809.11420-1-nstange@suse.de> References: <20211115141809.11420-1-nstange@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Currently, the DRBG implementation schedules asynchronous works from random_ready_callbacks for reseeding the DRBG instances with output from get_random_bytes() once the latter has sufficient entropy available. However, as the get_random_bytes() initialization state can get queried by means of rng_is_initialized() now, there is no real need for this asynchronous reseeding logic anymore and it's better to keep things simple by doing it synchronously when needed instead, i.e. from drbg_generate() once rng_is_initialized() has flipped to true. Of course, for this to work, drbg_generate() would need some means by which it can tell whether or not rng_is_initialized() has flipped to true since the last seeding from get_random_bytes(). Or equivalently, whether or not the last seed from get_random_bytes() has happened when rng_is_initialized() was still evaluating to false. As it currently stands, enum drbg_seed_state allows for the representation of two different DRBG seeding states: DRBG_SEED_STATE_UNSEEDED and DRBG_SEED_STATE_FULL. The former makes drbg_generate() to invoke a full reseeding operation involving both, the rather expensive jitterentropy as well as the get_random_bytes() randomness sources. The DRBG_SEED_STATE_FULL state on the other hand implies that no reseeding at all is required for a !->pr DRBG variant. Introduce the new DRBG_SEED_STATE_PARTIAL state to enum drbg_seed_state for representing the condition that a DRBG was being seeded when rng_is_initialized() had still been false. In particular, this new state implies that - the given DRBG instance has been fully seeded from the jitterentropy source (if enabled) - and drbg_generate() is supposed to reseed from get_random_bytes() *only* once rng_is_initialized() turns to true. Up to now, the __drbg_seed() helper used to set the given DRBG instance's ->seeded state to constant DRBG_SEED_STATE_FULL. Introduce a new argument allowing for the specification of the to be written ->seeded value instead. Make the first of its two callers, drbg_seed(), determine the appropriate value based on rng_is_initialized(). The remaining caller, drbg_async_seed(), is known to get invoked only once rng_is_initialized() is true, hence let it pass constant DRBG_SEED_STATE_FULL for the new argument to __drbg_seed(). There is no change in behaviour, except for that the pr_devel() in drbg_generate() would now report "unseeded" for ->pr DRBG instances which had last been seeded when rng_is_initialized() was still evaluating to false. Signed-off-by: Nicolai Stange Reviewed-by: Stephan Müller --- crypto/drbg.c | 12 ++++++++---- include/crypto/drbg.h | 1 + 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/crypto/drbg.c b/crypto/drbg.c index 6329c70e5bbb..d71c704d0cd2 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -1036,14 +1036,14 @@ static const struct drbg_state_ops drbg_hash_ops = { ******************************************************************/ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, - int reseed) + int reseed, enum drbg_seed_state new_seed_state) { int ret = drbg->d_ops->update(drbg, seed, reseed); if (ret) return ret; - drbg->seeded = DRBG_SEED_STATE_FULL; + drbg->seeded = new_seed_state; /* 10.1.1.2 / 10.1.1.3 step 5 */ drbg->reseed_ctr = 1; @@ -1093,7 +1093,7 @@ static void drbg_async_seed(struct work_struct *work) */ drbg->seeded = DRBG_SEED_STATE_UNSEEDED; - __drbg_seed(drbg, &seedlist, true); + __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL); if (drbg->seeded == DRBG_SEED_STATE_FULL) drbg->reseed_threshold = drbg_max_requests(drbg); @@ -1123,6 +1123,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, unsigned int entropylen = drbg_sec_strength(drbg->core->flags); struct drbg_string data1; LIST_HEAD(seedlist); + enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL; /* 9.1 / 9.2 / 9.3.1 step 3 */ if (pers && pers->len > (drbg_max_addtl(drbg))) { @@ -1150,6 +1151,9 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, BUG_ON((entropylen * 2) > sizeof(entropy)); /* Get seed from in-kernel /dev/urandom */ + if (!rng_is_initialized()) + new_seed_state = DRBG_SEED_STATE_PARTIAL; + ret = drbg_get_random_bytes(drbg, entropy, entropylen); if (ret) goto out; @@ -1206,7 +1210,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, memset(drbg->C, 0, drbg_statelen(drbg)); } - ret = __drbg_seed(drbg, &seedlist, reseed); + ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state); out: memzero_explicit(entropy, entropylen * 2); diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index 92a87b23ad2f..3ebdb1effe74 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -107,6 +107,7 @@ struct drbg_test_data { enum drbg_seed_state { DRBG_SEED_STATE_UNSEEDED, + DRBG_SEED_STATE_PARTIAL, /* Seeded with !rng_is_initialized() */ DRBG_SEED_STATE_FULL, };