From patchwork Fri Jul 7 10:22:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Harald Freudenberger X-Patchwork-Id: 9829903 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 E992F60317 for ; Fri, 7 Jul 2017 10:22:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C5E1D28526 for ; Fri, 7 Jul 2017 10:22:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BA6222865B; Fri, 7 Jul 2017 10:22:52 +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 99F282865E for ; Fri, 7 Jul 2017 10:22:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750977AbdGGKWu (ORCPT ); Fri, 7 Jul 2017 06:22:50 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:54881 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904AbdGGKWt (ORCPT ); Fri, 7 Jul 2017 06:22:49 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v67AIlfm015258 for ; Fri, 7 Jul 2017 06:22:49 -0400 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2bj443hkw9-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 07 Jul 2017 06:22:49 -0400 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 7 Jul 2017 11:22:43 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v67AMg0R37814404; Fri, 7 Jul 2017 10:22:42 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5FE7411C04C; Fri, 7 Jul 2017 11:20:16 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E565411C052; Fri, 7 Jul 2017 11:20:15 +0100 (BST) Received: from [10.0.2.15] (unknown [9.81.131.143]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 7 Jul 2017 11:20:15 +0100 (BST) Subject: Re: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng To: PrasannaKumar Muralidharan Cc: linux-crypto@vger.kernel.org, Herbert Xu , Arnd Bergmann , Greg KH , schwidefsky@de.ibm.com References: <1499076204-18547-1-git-send-email-freude@linux.vnet.ibm.com> <1499076204-18547-4-git-send-email-freude@linux.vnet.ibm.com> <0954fe1d-e0ff-6b35-6d2d-96901cad6503@linux.vnet.ibm.com> From: Harald Freudenberger Date: Fri, 7 Jul 2017 12:22:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 17070710-0008-0000-0000-0000047B2DEC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17070710-0009-0000-0000-00001E0599F6 Message-Id: <2cfcef13-2315-6bbe-4eda-ee019c870ce8@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-07-07_05:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1707070169 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 On 07/06/2017 06:51 AM, PrasannaKumar Muralidharan wrote: > Hi Harald, > >> Here is an updated version with just showing 0 or 1 in the new sysfs >> attribute file: >> ========== cut ========== >> From: Harald Freudenberger >> Date: Mon, 3 Jul 2017 10:19:22 +0200 >> Subject: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected >> rng >> >> This patch introduces a new sysfs attribute file 'rng_selected' >> which shows if the current rng has been chosen by userspace. ... > Nice to see quick turn around time. Why not just use the > cur_rng_set_by_user instead of selected_rng? This way patch 3 won't > change things that patch 2 introduced and patch 3 will become much > smaller. Also I feel folding patch 3 and 2 will make sense as both are > related to user selected rng. > > Regards, > PrasannaKumar > Hello PrasannaKumar here is now a version which combines patch 2 and patch 3 together according to your suggestions: ========== cut ========== From: Harald Freudenberger Date: Fri, 30 Jun 2017 17:06:40 +0200 Subject: [PATCH 2/2] crypto: hwrng remember rng chosen by user When a user chooses a rng source via sysfs attribute this rng should be sticky, even when other sources with better quality to register. This patch introduces a simple way to remember the user's choice. This is reflected by a new sysfs attribute file 'rng_selected' which shows if the current rng has been chosen by userspace. The new attribute file shows '1' for user selected rng and '0' otherwise. Signed-off-by: Harald Freudenberger --- drivers/char/hw_random/core.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index e9dda16..9701ac7 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -28,6 +28,8 @@ #define RNG_MODULE_NAME "hw_random" static struct hwrng *current_rng; +/* the current rng has been explicitly chosen by user via sysfs */ +static int cur_rng_set_by_user; static struct task_struct *hwrng_fill; /* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev, list_for_each_entry(rng, &rng_list, list) { if (sysfs_streq(rng->name, buf)) { err = 0; + cur_rng_set_by_user = 1; if (rng != current_rng) err = set_current_rng(rng); break; @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device *dev, return strlen(buf); } +static ssize_t hwrng_attr_selected_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user); +} + static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, hwrng_attr_current_show, hwrng_attr_current_store); static DEVICE_ATTR(rng_available, S_IRUGO, hwrng_attr_available_show, NULL); +static DEVICE_ATTR(rng_selected, S_IRUGO, + hwrng_attr_selected_show, + NULL); static struct attribute *rng_dev_attrs[] = { &dev_attr_rng_current.attr, &dev_attr_rng_available.attr, + &dev_attr_rng_selected.attr, NULL }; @@ -444,10 +458,12 @@ int hwrng_register(struct hwrng *rng) old_rng = current_rng; err = 0; - if (!old_rng || (rng->quality > old_rng->quality)) { + if (!old_rng || + (!cur_rng_set_by_user && rng->quality > old_rng->quality)) { /* * Set new rng as current as the new rng source - * provides better entropy quality. + * provides better entropy quality and was not + * chosen by userspace. */ err = set_current_rng(rng); if (err) @@ -479,6 +495,7 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); + cur_rng_set_by_user = 0; /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { struct hwrng *new_rng;