From mboxrd@z Thu Jan 1 00:00:00 1970 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 C915FC47090 for ; Mon, 5 Dec 2022 21:00:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233701AbiLEVAh (ORCPT ); Mon, 5 Dec 2022 16:00:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233565AbiLEVA1 (ORCPT ); Mon, 5 Dec 2022 16:00:27 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0FE78286D5; Mon, 5 Dec 2022 13:00:26 -0800 (PST) Received: from W11-BEAU-MD.localdomain (unknown [76.135.50.127]) by linux.microsoft.com (Postfix) with ESMTPSA id 9192920B83FD; Mon, 5 Dec 2022 13:00:26 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 9192920B83FD DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1670274026; bh=ucj0phlrsCOCEABbc8SVcAnCMpVQNUXl97uuBXh5AeA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZpW5UiMShhFrc1MZzv+BVEtEbMbF09uVJiIJD+xgp6o799MPeXyg/21r7xHGYAqkA fVFvqkEPeO0bgRyAyJ3ObF0WjYJ/jT7fOWK3tJ0+JMkqOv79612p86F9LTguegWQ7t FN9OEDrfsv6ZPGoow58tSuQzaCwAObTLFgjVLa10= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com, brauner@kernel.org, akpm@linux-foundation.org Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 11/11] tracing/user_events: Limit global user_event count Date: Mon, 5 Dec 2022 13:00:17 -0800 Message-Id: <20221205210017.23440-12-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221205210017.23440-1-beaub@linux.microsoft.com> References: <20221205210017.23440-1-beaub@linux.microsoft.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Operators want to be able to ensure enough tracepoints exist on the system for kernel components as well as for user components. Since there are only up to 64K events, by default allow up to half to be used by user events. Add a boot parameter (user_events_max=%d) and a kernel sysctl parameter (kernel.user_events_max) to set a global limit that is honored among all groups on the system. This ensures hard limits can be setup to prevent user processes from consuming all event IDs on the system. Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 57 ++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 36def244a755..754942ba92a1 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include "trace.h" #include "trace_dynevent.h" @@ -61,6 +62,12 @@ struct user_event_group { /* Group for init_user_ns mapping, top-most group */ static struct user_event_group *init_group; +/* Max allowed events for the whole system */ +static unsigned int max_user_events = 32768; + +/* Current number of events on the whole system */ +static unsigned int current_user_events; + /* * Stores per-event properties, as users register events * within a file a user_event might be created if it does not @@ -1247,6 +1254,11 @@ static int destroy_user_event(struct user_event *user) kfree(EVENT_NAME(user)); kfree(user); + if (current_user_events > 0) + current_user_events--; + else + pr_alert("BUG: Bad current_user_events\n"); + return ret; } @@ -1732,6 +1744,11 @@ static int user_event_parse(struct user_event_group *group, char *name, mutex_lock(&event_mutex); + if (current_user_events >= max_user_events) { + ret = -EMFILE; + goto put_user_lock; + } + ret = user_event_trace_register(user); if (ret) @@ -1743,6 +1760,7 @@ static int user_event_parse(struct user_event_group *group, char *name, dyn_event_init(&user->devent, &user_event_dops); dyn_event_add(&user->devent, &user->call); hash_add(group->register_table, &user->node, key); + current_user_events++; mutex_unlock(&event_mutex); @@ -2369,6 +2387,43 @@ static int create_user_tracefs(void) return -ENODEV; } +static int __init set_max_user_events(char *str) +{ + if (!str) + return 0; + + if (kstrtouint(str, 0, &max_user_events)) + return 0; + + return 1; +} +__setup("user_events_max=", set_max_user_events); + +static int set_max_user_events_sysctl(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + int ret; + + mutex_lock(&event_mutex); + + ret = proc_douintvec(table, write, buffer, lenp, ppos); + + mutex_unlock(&event_mutex); + + return ret; +} + +static struct ctl_table user_event_sysctls[] = { + { + .procname = "user_events_max", + .data = &max_user_events, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = set_max_user_events_sysctl, + }, + {} +}; + static int __init trace_events_user_init(void) { int ret; @@ -2398,6 +2453,8 @@ static int __init trace_events_user_init(void) if (dyn_event_register(&user_event_dops)) pr_warn("user_events could not register with dyn_events\n"); + register_sysctl_init("kernel", user_event_sysctls); + return 0; } -- 2.25.1