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 E3FD0C43217 for ; Mon, 21 Mar 2022 14:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348742AbiCUODu (ORCPT ); Mon, 21 Mar 2022 10:03:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349076AbiCUODS (ORCPT ); Mon, 21 Mar 2022 10:03:18 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B09BD173F4F; Mon, 21 Mar 2022 07:00:18 -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 ams.source.kernel.org (Postfix) with ESMTPS id 29D76B81598; Mon, 21 Mar 2022 14:00:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76117C36AE3; Mon, 21 Mar 2022 13:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1647871198; bh=AJsb5X7wBUotw3TxRY558vOtFqFD4GfaPxqom60XZWc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zYRuZpBAYBW4/2WRhxseoHR+fn7KbiV7FpLObLsxLyFQJfFx4M2YC29HE33MMqKGl /ipdXC+y240K0xn4w/9tAM1nQ1iCiooLHskqNUCnYVwpvnADrPpMdWmrzrb/jo/L+l eSCClv37QgM/aBIfTcQPs8j59/6PMEAJP5lSr4io= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brian Masney , Bjorn Andersson , Andrew Halaney , Herbert Xu Subject: [PATCH 5.15 01/32] crypto: qcom-rng - ensure buffer for generate is completely filled Date: Mon, 21 Mar 2022 14:52:37 +0100 Message-Id: <20220321133220.604619228@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220321133220.559554263@linuxfoundation.org> References: <20220321133220.559554263@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore 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: Brian Masney commit a680b1832ced3b5fa7c93484248fd221ea0d614b upstream. The generate function in struct rng_alg expects that the destination buffer is completely filled if the function returns 0. qcom_rng_read() can run into a situation where the buffer is partially filled with randomness and the remaining part of the buffer is zeroed since qcom_rng_generate() doesn't check the return value. This issue can be reproduced by running the following from libkcapi: kcapi-rng -b 9000000 > OUTFILE The generated OUTFILE will have three huge sections that contain all zeros, and this is caused by the code where the test 'val & PRNG_STATUS_DATA_AVAIL' fails. Let's fix this issue by ensuring that qcom_rng_read() always returns with a full buffer if the function returns success. Let's also have qcom_rng_generate() return the correct value. Here's some statistics from the ent project (https://www.fourmilab.ch/random/) that shows information about the quality of the generated numbers: $ ent -c qcom-random-before Value Char Occurrences Fraction 0 606748 0.067416 1 33104 0.003678 2 33001 0.003667 ... 253 � 32883 0.003654 254 � 33035 0.003671 255 � 33239 0.003693 Total: 9000000 1.000000 Entropy = 7.811590 bits per byte. Optimum compression would reduce the size of this 9000000 byte file by 2 percent. Chi square distribution for 9000000 samples is 9329962.81, and randomly would exceed this value less than 0.01 percent of the times. Arithmetic mean value of data bytes is 119.3731 (127.5 = random). Monte Carlo value for Pi is 3.197293333 (error 1.77 percent). Serial correlation coefficient is 0.159130 (totally uncorrelated = 0.0). Without this patch, the results of the chi-square test is 0.01%, and the numbers are certainly not random according to ent's project page. The results improve with this patch: $ ent -c qcom-random-after Value Char Occurrences Fraction 0 35432 0.003937 1 35127 0.003903 2 35424 0.003936 ... 253 � 35201 0.003911 254 � 34835 0.003871 255 � 35368 0.003930 Total: 9000000 1.000000 Entropy = 7.999979 bits per byte. Optimum compression would reduce the size of this 9000000 byte file by 0 percent. Chi square distribution for 9000000 samples is 258.77, and randomly would exceed this value 42.24 percent of the times. Arithmetic mean value of data bytes is 127.5006 (127.5 = random). Monte Carlo value for Pi is 3.141277333 (error 0.01 percent). Serial correlation coefficient is 0.000468 (totally uncorrelated = 0.0). This change was tested on a Nexus 5 phone (msm8974 SoC). Signed-off-by: Brian Masney Fixes: ceec5f5b5988 ("crypto: qcom-rng - Add Qcom prng driver") Cc: stable@vger.kernel.org # 4.19+ Reviewed-by: Bjorn Andersson Reviewed-by: Andrew Halaney Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- drivers/crypto/qcom-rng.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/drivers/crypto/qcom-rng.c +++ b/drivers/crypto/qcom-rng.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -43,16 +44,19 @@ static int qcom_rng_read(struct qcom_rng { unsigned int currsize = 0; u32 val; + int ret; /* read random data from hardware */ do { - val = readl_relaxed(rng->base + PRNG_STATUS); - if (!(val & PRNG_STATUS_DATA_AVAIL)) - break; + ret = readl_poll_timeout(rng->base + PRNG_STATUS, val, + val & PRNG_STATUS_DATA_AVAIL, + 200, 10000); + if (ret) + return ret; val = readl_relaxed(rng->base + PRNG_DATA_OUT); if (!val) - break; + return -EINVAL; if ((max - currsize) >= WORD_SZ) { memcpy(data, &val, WORD_SZ); @@ -61,11 +65,10 @@ static int qcom_rng_read(struct qcom_rng } else { /* copy only remaining bytes */ memcpy(data, &val, max - currsize); - break; } } while (currsize < max); - return currsize; + return 0; } static int qcom_rng_generate(struct crypto_rng *tfm, @@ -87,7 +90,7 @@ static int qcom_rng_generate(struct cryp mutex_unlock(&rng->lock); clk_disable_unprepare(rng->clk); - return 0; + return ret; } static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,