From mboxrd@z Thu Jan 1 00:00:00 1970 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 13571C433EF for ; Fri, 3 Jun 2022 17:53:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345504AbiFCRxp (ORCPT ); Fri, 3 Jun 2022 13:53:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346579AbiFCRvS (ORCPT ); Fri, 3 Jun 2022 13:51:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2013157124; Fri, 3 Jun 2022 10:48:41 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9D54960F7F; Fri, 3 Jun 2022 17:48:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E306C385A9; Fri, 3 Jun 2022 17:48:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654278520; bh=bA32dH1FbReMD6dkPhjw3sLV/3rPluZTJVYOKOMlN8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GAitTYYF9rQVDpo/S80ToYmBR3CmU9IkzFJaORvKjNu2ZMzEitYmHN6cTq+ajVhsi 4liNF9P0PIiGBMX1gHmkRZSy3s/i/JnDt26H6H8Oeqpz+Vz+/QAeZd2aQxm64feOcW XYtitBy+lPTg+FbEWNu4V+bCPhyVhsaMr1NswyuE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicolai Stange , =?UTF-8?q?Stephan=20M=C3=BCller?= , Herbert Xu , "Jason A. Donenfeld" Subject: [PATCH 5.10 26/53] crypto: drbg - track whether DRBG was seeded with !rng_is_initialized() Date: Fri, 3 Jun 2022 19:43:11 +0200 Message-Id: <20220603173819.486438097@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220603173818.716010877@linuxfoundation.org> References: <20220603173818.716010877@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nicolai Stange commit 2bcd25443868aa8863779a6ebc6c9319633025d2 upstream. 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 Signed-off-by: Herbert Xu Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- crypto/drbg.c | 12 ++++++++---- include/crypto/drbg.h | 1 + 2 files changed, 9 insertions(+), 4 deletions(-) --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -1035,14 +1035,14 @@ static const struct drbg_state_ops drbg_ ******************************************************************/ 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; @@ -1092,7 +1092,7 @@ static void drbg_async_seed(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); @@ -1122,6 +1122,7 @@ static int drbg_seed(struct drbg_state * 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))) { @@ -1149,6 +1150,9 @@ static int drbg_seed(struct drbg_state * 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; @@ -1205,7 +1209,7 @@ static int drbg_seed(struct drbg_state * 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); --- 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, };