From patchwork Tue Jul 11 07:36:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Harald Freudenberger X-Patchwork-Id: 9834203 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A07F460363 for ; Tue, 11 Jul 2017 07:37:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9060A2623C for ; Tue, 11 Jul 2017 07:37:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8231D27FB7; Tue, 11 Jul 2017 07:37:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1FE422623C for ; Tue, 11 Jul 2017 07:37:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755386AbdGKHhR (ORCPT ); Tue, 11 Jul 2017 03:37:17 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34373 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755410AbdGKHhK (ORCPT ); Tue, 11 Jul 2017 03:37:10 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6B7YMqA060392 for ; Tue, 11 Jul 2017 03:37:09 -0400 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0b-001b2d01.pphosted.com with ESMTP id 2bmc7nbdhk-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 11 Jul 2017 03:37:09 -0400 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 11 Jul 2017 08:37:04 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v6B7b4oJ16515436; Tue, 11 Jul 2017 07:37:04 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E1E7752043; Tue, 11 Jul 2017 07:33:24 +0100 (BST) Received: from mymint.boeblingen.de.ibm.com (unknown [9.83.224.226]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 6C3AF5203F; Tue, 11 Jul 2017 07:33:24 +0100 (BST) From: Harald Freudenberger To: linux-crypto@vger.kernel.org Cc: herbert@gondor.apana.org.au, arnd@arndb.de, gregkh@linuxfoundation.org, prasannatsmkumar@gmail.com, schwidefsky@de.ibm.com, Harald Freudenberger Subject: [PATCH 1/2] crypto: hwrng use rng source with best quality Date: Tue, 11 Jul 2017 09:36:22 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1499758583-14626-1-git-send-email-freude@linux.vnet.ibm.com> References: <1499758583-14626-1-git-send-email-freude@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17071107-0040-0000-0000-000003E092D2 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071107-0041-0000-0000-0000207B7B6A Message-Id: <1499758583-14626-2-git-send-email-freude@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-07-11_03:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1707110116 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch rewoks the hwrng to always use the rng source with best entropy quality. On registation and unregistration the hwrng now tries to choose the best (= highest quality value) rng source. The handling of the internal list of registered rng sources is now always sorted by quality and the top most rng chosen. Signed-off-by: Harald Freudenberger Reviewed-by: PrasannaKumar Muralidharan --- drivers/char/hw_random/core.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 503a41d..e9dda16 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -29,6 +29,7 @@ static struct hwrng *current_rng; static struct task_struct *hwrng_fill; +/* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); /* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); @@ -417,6 +418,7 @@ int hwrng_register(struct hwrng *rng) { int err = -EINVAL; struct hwrng *old_rng, *tmp; + struct list_head *rng_list_ptr; if (!rng->name || (!rng->data_read && !rng->read)) goto out; @@ -432,14 +434,25 @@ int hwrng_register(struct hwrng *rng) init_completion(&rng->cleanup_done); complete(&rng->cleanup_done); + /* rng_list is sorted by decreasing quality */ + list_for_each(rng_list_ptr, &rng_list) { + tmp = list_entry(rng_list_ptr, struct hwrng, list); + if (tmp->quality < rng->quality) + break; + } + list_add_tail(&rng->list, rng_list_ptr); + old_rng = current_rng; err = 0; - if (!old_rng) { + if (!old_rng || (rng->quality > old_rng->quality)) { + /* + * Set new rng as current as the new rng source + * provides better entropy quality. + */ err = set_current_rng(rng); if (err) goto out_unlock; } - list_add_tail(&rng->list, &rng_list); if (old_rng && !rng->init) { /* @@ -466,12 +479,12 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); + /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { - struct hwrng *tail; - - tail = list_entry(rng_list.prev, struct hwrng, list); + struct hwrng *new_rng; - set_current_rng(tail); + new_rng = list_entry(rng_list.next, struct hwrng, list); + set_current_rng(new_rng); } }