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 X-Spam-Level: X-Spam-Status: No, score=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBAF9C6778F for ; Thu, 26 Jul 2018 05:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CEAD2089B for ; Thu, 26 Jul 2018 05:53:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="2KeijGWl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6CEAD2089B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728741AbeGZHJB (ORCPT ); Thu, 26 Jul 2018 03:09:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:41862 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726763AbeGZHJB (ORCPT ); Thu, 26 Jul 2018 03:09:01 -0400 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1E6012083F; Thu, 26 Jul 2018 05:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532584430; bh=wKtA8dVYIC2MKtiA5TkkeTwRU9qWGBDukujcBOvGk1M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2KeijGWlrf6CELQZw+r1Od764Un2nJYoFmvBhDfQ7JAbRGK20jYI8e165xEBGYwLY KdJRaFZfyaCJaueDEDQczR+kmlQ1nZyWb16m4B64lHOfvxmmg43w3tPEAJO3pM9NqV QcVIucdYK444Zl53g8ITuUPKz4LOy3biEOdAVTO8= From: Masami Hiramatsu To: rostedt@goodmis.org, Francis Deslauriers , peterz@infradead.org Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/3] tracing: kprobes: Prohibit probing on notrace function Date: Thu, 26 Jul 2018 14:53:27 +0900 Message-Id: <153258440707.11602.3706182300882155086.stgit@devbox> X-Mailer: git-send-email 2.13.6 In-Reply-To: <153258437722.11602.12405835083073480618.stgit@devbox> References: <153258437722.11602.12405835083073480618.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Prohibit kprobe-events probing on notrace function. Since probing on the notrace function can cause recursive event call. In most case those are just skipped, but in some case it falls into infinit recursive call. This protection can be disabled by the kconfig CONFIG_KPROBE_EVENTS_ON_NOTRACE=y, but it is highly recommended to keep it "n" for normal kernel. Signed-off-by: Masami Hiramatsu Tested-by: Francis Deslauriers --- Changes from v1 - Add CONFIG_KPROBE_EVENTS_ON_NOTRACE kconfig for knocking down the protection. --- kernel/trace/Kconfig | 18 ++++++++++++++++++ kernel/trace/trace_kprobe.c | 23 +++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index dcc0166d1997..24d5a58467a3 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -456,6 +456,24 @@ config KPROBE_EVENTS This option is also required by perf-probe subcommand of perf tools. If you want to use perf tools, this option is strongly recommended. +config KPROBE_EVENTS_ON_NOTRACE + bool "Do NOT protect notrace function from kprobe events" + depends on KPROBE_EVENTS + default n + help + This is only for the developers who want to debug ftrace itself + using kprobe events. + + Usually, ftrace related functions are protected from kprobe-events + to prevent an infinit recursion or any unexpected execution path + which leads to a kernel crash. + + This option disables such protection and allows you to put kprobe + events on ftrace functions for debugging ftrace by itself. + Note that this might let you shoot yourself in the foot. + + If unsure, say N. + config UPROBE_EVENTS bool "Enable uprobes-based dynamic events" depends on ARCH_SUPPORTS_UPROBES diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 27ace4513c43..1f1b4d712a7e 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -496,6 +496,23 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) return ret; } +#ifdef CONFIG_KPROBE_EVENTS_ON_NOTRACE +#define within_notrace_func(tk) (false) +#else +static bool within_notrace_func(struct trace_kprobe *tk) +{ + unsigned long offset, size, addr; + + addr = kallsyms_lookup_name(trace_kprobe_symbol(tk)); + addr += trace_kprobe_offset(tk); + + if (!kallsyms_lookup_size_offset(addr, &size, &offset)) + return true; /* Out of range. */ + + return !ftrace_location_range(addr - offset, addr - offset + size); +} +#endif + /* Internal register function - just handle k*probes and flags */ static int __register_trace_kprobe(struct trace_kprobe *tk) { @@ -504,6 +521,12 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) if (trace_probe_is_registered(&tk->tp)) return -EINVAL; + if (within_notrace_func(tk)) { + pr_warn("Could not probe notrace function %s\n", + trace_kprobe_symbol(tk)); + return -EINVAL; + } + for (i = 0; i < tk->tp.nr_args; i++) traceprobe_update_arg(&tk->tp.args[i]);