From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-path: Received: from mail-lf0-f68.google.com ([209.85.215.68]:42842 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752160AbeC0IKF (ORCPT ); Tue, 27 Mar 2018 04:10:05 -0400 Received: by mail-lf0-f68.google.com with SMTP id a22-v6so31960362lfg.9 for ; Tue, 27 Mar 2018 01:10:05 -0700 (PDT) From: Marcus Folkesson To: Wim Van Sebroeck , Guenter Roeck Cc: linux-watchdog@vger.kernel.org, Marcus Folkesson Subject: [PATCH] watchdog: core: add option to make timeouts read-only Date: Tue, 27 Mar 2018 10:09:41 +0200 Message-Id: <20180327080941.29235-2-marcus.folkesson@gmail.com> In-Reply-To: <20180327080941.29235-1-marcus.folkesson@gmail.com> References: <20180327080941.29235-1-marcus.folkesson@gmail.com> Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org Some systems may not allow applications to configure the watchdog timer at all. This restriction is not limited to stop the watchdog, but also change timeouts as well. This adds a kernel parameter to disable the ability to change the watchdog timouts from userspace. Signed-off-by: Marcus Folkesson --- drivers/watchdog/Kconfig | 9 +++++++++ drivers/watchdog/watchdog_dev.c | 12 ++++++++++-- 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index aff773bcebdb..bcba48b5c88b 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig @@ -46,6 +46,15 @@ config WATCHDOG_NOWAYOUT get killed. If you say Y here, the watchdog cannot be stopped once it has been started. +config WATCHDOG_TIMEOUT_READONLY + bool "Make timeouts read-only from userspace" + help + Say Y here if you want the watchdog timeout/pretimeout to be read-only + from userspace. This requires that the timeout is configured before + userspace takes over. + + Say N if you are unsure. + config WATCHDOG_HANDLE_BOOT_ENABLED bool "Update boot-enabled watchdog until userspace takes over" default y diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index ffbdc4642ea5..6064806a2a8d 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -87,6 +87,9 @@ static struct kthread_worker *watchdog_kworker; static bool handle_boot_enabled = IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); +static bool timeout_is_readonly = + IS_ENABLED(CONFIG_WATCHDOG_TIMEOUT_READONLY); + static inline bool watchdog_need_worker(struct watchdog_device *wdd) { /* All variables in milli-seconds */ @@ -359,7 +362,7 @@ static int watchdog_set_timeout(struct watchdog_device *wdd, { int err = 0; - if (!(wdd->info->options & WDIOF_SETTIMEOUT)) + if (!(wdd->info->options & WDIOF_SETTIMEOUT) || timeout_is_readonly) return -EOPNOTSUPP; if (watchdog_timeout_invalid(wdd, timeout)) @@ -390,7 +393,7 @@ static int watchdog_set_pretimeout(struct watchdog_device *wdd, { int err = 0; - if (!(wdd->info->options & WDIOF_PRETIMEOUT)) + if (!(wdd->info->options & WDIOF_PRETIMEOUT) || timeout_is_readonly) return -EOPNOTSUPP; if (watchdog_pretimeout_invalid(wdd, timeout)) @@ -1181,3 +1184,8 @@ module_param(handle_boot_enabled, bool, 0444); MODULE_PARM_DESC(handle_boot_enabled, "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); + +module_param(timeout_is_readonly, bool, 0444); +MODULE_PARM_DESC(timeout_is_readonly, + "Watchdog timeouts is readonly from userspace (default=" + __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_TIMEOUT_READONLY)) ")"); -- 2.16.2