From patchwork Sun Feb 13 20:46:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dominik Brodowski X-Patchwork-Id: 542620 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 6F815C433FE for ; Sun, 13 Feb 2022 20:50:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238261AbiBMUuX (ORCPT ); Sun, 13 Feb 2022 15:50:23 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:55664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230399AbiBMUuX (ORCPT ); Sun, 13 Feb 2022 15:50:23 -0500 Received: from isilmar-4.linta.de (isilmar-4.linta.de [136.243.71.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCC1453707; Sun, 13 Feb 2022 12:50:16 -0800 (PST) X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from owl.dominikbrodowski.net (owl.brodo.linta [10.2.0.111]) by isilmar-4.linta.de (Postfix) with ESMTPSA id 3D420200C43; Sun, 13 Feb 2022 20:50:15 +0000 (UTC) Received: by owl.dominikbrodowski.net (Postfix, from userid 1000) id CBC488087D; Sun, 13 Feb 2022 21:48:08 +0100 (CET) From: Dominik Brodowski To: Herbert Xu Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, "Jason A . Donenfeld" Subject: [PATCH 1/4] hw_random: do not bother to order list of devices by quality Date: Sun, 13 Feb 2022 21:46:28 +0100 Message-Id: <20220213204631.354247-2-linux@dominikbrodowski.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220213204631.354247-1-linux@dominikbrodowski.net> References: <20220213204631.354247-1-linux@dominikbrodowski.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org There is no real reason why this list needs to be kept ordered by the driver-provided quality value -- a value which is set only by a handful of hw_random devices anyway. Cc: Herbert Xu Cc: Jason A. Donenfeld Signed-off-by: Dominik Brodowski --- drivers/char/hw_random/core.c | 36 ++++++++++++++++------------------- 1 file changed, 16 insertions(+), 20 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index f327f7493585..6f09f4e5af20 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -31,7 +31,7 @@ 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 */ +/* list of registered rngs */ static LIST_HEAD(rng_list); /* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); @@ -297,24 +297,28 @@ static struct miscdevice rng_miscdev = { static int enable_best_rng(void) { + struct hwrng *rng, *new_rng = NULL; int ret = -ENODEV; BUG_ON(!mutex_is_locked(&rng_mutex)); - /* rng_list is sorted by quality, use the best (=first) one */ - if (!list_empty(&rng_list)) { - struct hwrng *new_rng; - - new_rng = list_entry(rng_list.next, struct hwrng, list); - ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng)); - if (!ret) - cur_rng_set_by_user = 0; - } else { + /* no rng to use? */ + if (list_empty(&rng_list)) { drop_current_rng(); cur_rng_set_by_user = 0; - ret = 0; + return 0; } + /* use the rng which offers the best quality */ + list_for_each_entry(rng, &rng_list, list) { + if (!new_rng || rng->quality > new_rng->quality) + new_rng = rng; + } + + ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng)); + if (!ret) + cur_rng_set_by_user = 0; + return ret; } @@ -475,7 +479,6 @@ int hwrng_register(struct hwrng *rng) { int err = -EINVAL; struct hwrng *tmp; - struct list_head *rng_list_ptr; bool is_new_current = false; if (!rng->name || (!rng->data_read && !rng->read)) @@ -489,18 +492,11 @@ int hwrng_register(struct hwrng *rng) if (strcmp(tmp->name, rng->name) == 0) goto out_unlock; } + list_add_tail(&rng->list, &rng_list); 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); - if (!current_rng || (!cur_rng_set_by_user && rng->quality > current_rng->quality)) { /* From patchwork Sun Feb 13 20:46:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dominik Brodowski X-Patchwork-Id: 542619 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 8D9CAC433F5 for ; Sun, 13 Feb 2022 20:50:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238285AbiBMUuY (ORCPT ); Sun, 13 Feb 2022 15:50:24 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:55676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238214AbiBMUuX (ORCPT ); Sun, 13 Feb 2022 15:50:23 -0500 Received: from isilmar-4.linta.de (isilmar-4.linta.de [136.243.71.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BD0B53723; Sun, 13 Feb 2022 12:50:17 -0800 (PST) X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from owl.dominikbrodowski.net (owl.brodo.linta [10.2.0.111]) by isilmar-4.linta.de (Postfix) with ESMTPSA id 58EC220133D; Sun, 13 Feb 2022 20:50:15 +0000 (UTC) Received: by owl.dominikbrodowski.net (Postfix, from userid 1000) id 58AF3808C5; Sun, 13 Feb 2022 21:48:21 +0100 (CET) From: Dominik Brodowski To: Herbert Xu Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, "Jason A . Donenfeld" Subject: [PATCH 2/4] hw_random: start and stop in-kernel rngd in separate function Date: Sun, 13 Feb 2022 21:46:29 +0100 Message-Id: <20220213204631.354247-3-linux@dominikbrodowski.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220213204631.354247-1-linux@dominikbrodowski.net> References: <20220213204631.354247-1-linux@dominikbrodowski.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Extract the start/stop logic for the in-kernel rngd thread to a separate function. Cc: Herbert Xu Cc: Jason A. Donenfeld Signed-off-by: Dominik Brodowski --- drivers/char/hw_random/core.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 6f09f4e5af20..29febf55b0d4 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -51,7 +51,7 @@ MODULE_PARM_DESC(default_quality, static void drop_current_rng(void); static int hwrng_init(struct hwrng *rng); -static void start_khwrngd(void); +static void hwrng_manage_rngd(void); static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, int wait); @@ -164,10 +164,7 @@ static int hwrng_init(struct hwrng *rng) if (current_quality > 1024) current_quality = 1024; - if (current_quality == 0 && hwrng_fill) - kthread_stop(hwrng_fill); - if (current_quality > 0 && !hwrng_fill) - start_khwrngd(); + hwrng_manage_rngd(); return 0; } @@ -466,12 +463,19 @@ static int hwrng_fillfn(void *unused) return 0; } -static void start_khwrngd(void) +static void hwrng_manage_rngd(void) { - hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng"); - if (IS_ERR(hwrng_fill)) { - pr_err("hwrng_fill thread creation failed\n"); - hwrng_fill = NULL; + if (WARN_ON(!mutex_is_locked(&rng_mutex))) + return; + + if (current_quality == 0 && hwrng_fill) + kthread_stop(hwrng_fill); + if (current_quality > 0 && !hwrng_fill) { + hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng"); + if (IS_ERR(hwrng_fill)) { + pr_err("hwrng_fill thread creation failed\n"); + hwrng_fill = NULL; + } } } From patchwork Sun Feb 13 20:46:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dominik Brodowski X-Patchwork-Id: 542418 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 BAF3DC4321E for ; Sun, 13 Feb 2022 20:50:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238286AbiBMUuY (ORCPT ); Sun, 13 Feb 2022 15:50:24 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:55672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238209AbiBMUuX (ORCPT ); Sun, 13 Feb 2022 15:50:23 -0500 Received: from isilmar-4.linta.de (isilmar-4.linta.de [136.243.71.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1680353715; Sun, 13 Feb 2022 12:50:16 -0800 (PST) X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from owl.dominikbrodowski.net (owl.brodo.linta [10.2.0.111]) by isilmar-4.linta.de (Postfix) with ESMTPSA id 58AB9201335; Sun, 13 Feb 2022 20:50:15 +0000 (UTC) Received: by owl.dominikbrodowski.net (Postfix, from userid 1000) id E59A5809A1; Sun, 13 Feb 2022 21:48:33 +0100 (CET) From: Dominik Brodowski To: Herbert Xu Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, "Jason A . Donenfeld" Subject: [PATCH 3/4] hw_random: use per-rng quality value instead of global setting Date: Sun, 13 Feb 2022 21:46:30 +0100 Message-Id: <20220213204631.354247-4-linux@dominikbrodowski.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220213204631.354247-1-linux@dominikbrodowski.net> References: <20220213204631.354247-1-linux@dominikbrodowski.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The current_quality variable exposed as a module parameter is fundamentally broken: If it is set at boot time, it is overwritten once the first hw rng device is loaded; if it is set at runtime, it is without effect if the hw rng device had its quality value set to 0 (and no default_quality was set); and if a new rng is selected, it gets overwritten. Therefore, mark it as obsolete, and replace it by the per-rng quality setting. Cc: Herbert Xu Cc: Jason A. Donenfeld Signed-off-by: Dominik Brodowski --- drivers/char/hw_random/core.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 29febf55b0d4..8df102b39b35 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -44,14 +44,14 @@ static unsigned short default_quality; /* = 0; default to "off" */ module_param(current_quality, ushort, 0644); MODULE_PARM_DESC(current_quality, - "current hwrng entropy estimation per 1024 bits of input"); + "current hwrng entropy estimation per 1024 bits of input -- obsolete"); module_param(default_quality, ushort, 0644); MODULE_PARM_DESC(default_quality, "default entropy content of hwrng per 1024 bits of input"); static void drop_current_rng(void); static int hwrng_init(struct hwrng *rng); -static void hwrng_manage_rngd(void); +static void hwrng_manage_rngd(struct hwrng *rng); static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, int wait); @@ -160,11 +160,13 @@ static int hwrng_init(struct hwrng *rng) reinit_completion(&rng->cleanup_done); skip_init: - current_quality = rng->quality ? : default_quality; - if (current_quality > 1024) - current_quality = 1024; + if (!rng->quality) + rng->quality = default_quality; + if (rng->quality > 1024) + rng->quality = 1024; + current_quality = rng->quality; /* obsolete */ - hwrng_manage_rngd(); + hwrng_manage_rngd(rng); return 0; } @@ -429,19 +431,24 @@ static int hwrng_fillfn(void *unused) long rc; while (!kthread_should_stop()) { + unsigned short quality; struct hwrng *rng; - if (!current_quality) - break; - rng = get_current_rng(); if (IS_ERR(rng) || !rng) break; mutex_lock(&reading_mutex); rc = rng_get_data(rng, rng_fillbuf, rng_buffer_size(), 1); + if (current_quality != rng->quality) + rng->quality = current_quality; /* obsolete */ + quality = rng->quality; mutex_unlock(&reading_mutex); put_rng(rng); + + if (!quality) + break; + if (rc <= 0) { pr_warn("hwrng: no data available\n"); msleep_interruptible(10000); @@ -451,7 +458,7 @@ static int hwrng_fillfn(void *unused) /* If we cannot credit at least one bit of entropy, * keep track of the remainder for the next iteration */ - entropy = rc * current_quality * 8 + entropy_credit; + entropy = rc * quality * 8 + entropy_credit; if ((entropy >> 10) == 0) entropy_credit = entropy; @@ -463,14 +470,14 @@ static int hwrng_fillfn(void *unused) return 0; } -static void hwrng_manage_rngd(void) +static void hwrng_manage_rngd(struct hwrng *rng) { if (WARN_ON(!mutex_is_locked(&rng_mutex))) return; - if (current_quality == 0 && hwrng_fill) + if (rng->quality == 0 && hwrng_fill) kthread_stop(hwrng_fill); - if (current_quality > 0 && !hwrng_fill) { + if (rng->quality > 0 && !hwrng_fill) { hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng"); if (IS_ERR(hwrng_fill)) { pr_err("hwrng_fill thread creation failed\n"); From patchwork Sun Feb 13 20:46:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dominik Brodowski X-Patchwork-Id: 542419 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 ACB31C43217 for ; Sun, 13 Feb 2022 20:50:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238280AbiBMUuY (ORCPT ); Sun, 13 Feb 2022 15:50:24 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:55674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238251AbiBMUuX (ORCPT ); Sun, 13 Feb 2022 15:50:23 -0500 Received: from isilmar-4.linta.de (isilmar-4.linta.de [136.243.71.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5AC2453717; Sun, 13 Feb 2022 12:50:16 -0800 (PST) X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from owl.dominikbrodowski.net (owl.brodo.linta [10.2.0.111]) by isilmar-4.linta.de (Postfix) with ESMTPSA id 53E292012E6; Sun, 13 Feb 2022 20:50:15 +0000 (UTC) Received: by owl.dominikbrodowski.net (Postfix, from userid 1000) id 8B45C80A0E; Sun, 13 Feb 2022 21:48:34 +0100 (CET) From: Dominik Brodowski To: Herbert Xu Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, "Jason A . Donenfeld" Subject: [PATCH 4/4] hw_random: introduce rng_quality sysfs attribute Date: Sun, 13 Feb 2022 21:46:31 +0100 Message-Id: <20220213204631.354247-5-linux@dominikbrodowski.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220213204631.354247-1-linux@dominikbrodowski.net> References: <20220213204631.354247-1-linux@dominikbrodowski.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The rng_quality sysfs attribute returns the quality setting for the currently active hw_random device, in entropy bits per 1024 bits of input. Storing a value between 0 and 1024 to this file updates this estimate accordingly. Based on the updates to the quality setting, the rngd kernel thread may be stopped (if no hw_random device is trusted to return entropy), may be started (if the quality setting is increased from zero), or may use a different hw_random source (if that has higher quality output). Cc: Herbert Xu Cc: Jason A. Donenfeld Signed-off-by: Dominik Brodowski --- drivers/char/hw_random/core.c | 64 ++++++++++++++++++++++++++++++++++- 1 file changed, 63 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 8df102b39b35..71eafcc451e1 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -44,7 +44,7 @@ static unsigned short default_quality; /* = 0; default to "off" */ module_param(current_quality, ushort, 0644); MODULE_PARM_DESC(current_quality, - "current hwrng entropy estimation per 1024 bits of input -- obsolete"); + "current hwrng entropy estimation per 1024 bits of input -- obsolete, use rng_quality instead"); module_param(default_quality, ushort, 0644); MODULE_PARM_DESC(default_quality, "default entropy content of hwrng per 1024 bits of input"); @@ -402,14 +402,76 @@ static ssize_t rng_selected_show(struct device *dev, return sysfs_emit(buf, "%d\n", cur_rng_set_by_user); } +static ssize_t rng_quality_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + ssize_t ret; + struct hwrng *rng; + + rng = get_current_rng(); + if (IS_ERR(rng)) + return PTR_ERR(rng); + + if (!rng) /* no need to put_rng */ + return -ENODEV; + + ret = sysfs_emit(buf, "%hu\n", rng->quality); + put_rng(rng); + + return ret; +} + +static ssize_t rng_quality_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + u16 quality; + int ret = -EINVAL; + + if (len < 2) + return -EINVAL; + + ret = mutex_lock_interruptible(&rng_mutex); + if (ret) + return -ERESTARTSYS; + + ret = kstrtou16(buf, 0, &quality); + if (ret || quality > 1024) { + ret = -EINVAL; + goto out; + } + + if (!current_rng) { + ret = -ENODEV; + goto out; + } + + current_rng->quality = quality; + current_quality = quality; /* obsolete */ + + /* the best available RNG may have changed */ + ret = enable_best_rng(); + + /* start/stop rngd if necessary */ + if (current_rng) + hwrng_manage_rngd(current_rng); + +out: + mutex_unlock(&rng_mutex); + return ret ? ret : len; +} + static DEVICE_ATTR_RW(rng_current); static DEVICE_ATTR_RO(rng_available); static DEVICE_ATTR_RO(rng_selected); +static DEVICE_ATTR_RW(rng_quality); static struct attribute *rng_dev_attrs[] = { &dev_attr_rng_current.attr, &dev_attr_rng_available.attr, &dev_attr_rng_selected.attr, + &dev_attr_rng_quality.attr, NULL };