From: Harald Freudenberger Subject: [PATCH 3/3] crypto: hwrng add sysfs attribute to show user selected rng Date: Mon, 3 Jul 2017 12:03:24 +0200 Message-ID: <1499076204-18547-4-git-send-email-freude@linux.vnet.ibm.com> References: <1499076204-18547-1-git-send-email-freude@linux.vnet.ibm.com> Cc: herbert@gondor.apana.org.au, arnd@arndb.de, gregkh@linuxfoundation.org, schwidefsky@de.ibm.com, Harald Freudenberger To: linux-crypto@vger.kernel.org Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:60046 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753800AbdGCKD4 (ORCPT ); Mon, 3 Jul 2017 06:03:56 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v639wirP133876 for ; Mon, 3 Jul 2017 06:03:56 -0400 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2bf27ar54q-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 03 Jul 2017 06:03:53 -0400 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 3 Jul 2017 11:03:50 +0100 In-Reply-To: <1499076204-18547-1-git-send-email-freude@linux.vnet.ibm.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: This patch introduces a new sysfs attribute file 'rng_selected' which shows the the rng chosen by userspace. If a rng source is chosen by user via echo some valid string to rng_current there should be a way to signal this choice to userspace. The new attribute file 'rng_selected' shows either the name of the rng chosen or 'none'. Signed-off-by: Harald Freudenberger --- drivers/char/hw_random/core.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index ffd4e36..6a6276a 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -28,8 +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; +/* the rng explicitly selected by user via sysfs */ +static struct hwrng *selected_rng; static struct task_struct *hwrng_fill; /* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); @@ -306,7 +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; + selected_rng = rng; if (rng != current_rng) err = set_current_rng(rng); break; @@ -355,16 +355,28 @@ 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, "%s\n", + selected_rng ? selected_rng->name : "none"); +} + 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 }; @@ -448,7 +460,7 @@ int hwrng_register(struct hwrng *rng) old_rng = current_rng; err = 0; if (!old_rng || - (!cur_rng_set_by_user && rng->quality > old_rng->quality)) { + (!selected_rng && rng->quality > old_rng->quality)) { /* * Set new rng as current as the new rng source * provides better entropy quality and was not @@ -484,7 +496,7 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); - cur_rng_set_by_user = 0; + selected_rng = NULL; /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { struct hwrng *new_rng; -- 2.7.4