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=-7.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,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 D6247C43387 for ; Sat, 12 Jan 2019 02:26:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E3202177B for ; Sat, 12 Jan 2019 02:26:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547259994; bh=aXBhIe8CTbdSb328zSKd7/uJOwq0P+xumiV61OdipRI=; h=From:To:Cc:Subject:Date:List-ID:From; b=rzq7nNorRn8NCXSCxVI5BVhudrhHGlotHDqNGt9/84qr3tDe716ai+ediUejClj+N JBuNzfFmVvuBvsFFFzS0gAWECmP3kldUPuq6ADa0n4ab3uD1Z56x6RR/FIqL87Wtbw P55LAuINI4SbWxI7jfiVYfZpnS6YS65fxnFiits4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726480AbfALC0E (ORCPT ); Fri, 11 Jan 2019 21:26:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:47552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726227AbfALC0E (ORCPT ); Fri, 11 Jan 2019 21:26:04 -0500 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 7414420872; Sat, 12 Jan 2019 02:26:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547259963; bh=aXBhIe8CTbdSb328zSKd7/uJOwq0P+xumiV61OdipRI=; h=From:To:Cc:Subject:Date:From; b=KtbQvA2CEO1JNN2NPyOj34P5s6S8dPQ8zT6VBqGCJ0ULgth0jDOnio/OgZSfPqEVB GTU2+6fjRJ6Qd8HUVEE4CFdI4TUzWVkR0x3P2QUTk6VMLpMIxKOhq1A8qpRADU9bVD kETCCjM8eh4MhDN3I4QA6PsIc1Y/Xjhd5AAhN8wc= From: Masami Hiramatsu To: Ingo Molnar Cc: Masami Hiramatsu , peterz@infradead.org, Mathieu Desnoyers , linux-kernel , Andrea Righi , Steven Rostedt Subject: [PATCH v2 0/9] kprobes: Fix and improve blacklist symbols Date: Sat, 12 Jan 2019 11:25:40 +0900 Message-Id: <154725993986.18060.2759150647140353514.stgit@devbox> X-Mailer: git-send-email 2.13.6 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 Hi, Here is the v2 series of kprobes blacklist bugfix and improvements mainly on x86 (since I started testing on qemu-x86). >>From v1, I just removed stable-ml from Cc (but tagged [1/9]) and added Steve's Ack. This has been started from discussion about KPROBE_ENENTS_ON_NOTRACE configuration. I tried to find notrace functions which can cause kernel crash with kprobes using following script. ==== #!/bin/sh i=0; cat notrace_functions | while read f ; do if echo p:event$i $f >> /sys/kernel/debug/tracing/kprobe_events; then echo "Probing on $f" echo 1 > /sys/kernel/debug/tracing/events/kprobes/event$i/enable fi i=$((i+1)) done ==== And I found several functions which must be blacklisted. - optprobe template code, which is just a template code and never be executed. Moreover, since it can be copied and reused, if we probe it, it modifies the template code and can cause a crash. ([1/9][2/9]) - functions which is called before kprobe_int3_handler() handles kprobes. This can cause a breakpoint recursion. ([3/9]) - IRQ entry text, which should not be probed since register/pagetable status has not been stable at that point. ([4/9]) - Suffixed symbols, like .constprop, .part etc. Those suffixed symbols never be blacklisted even if the non-suffixed version has been blacklisted. ([5/9]) - hardirq tracer also works before int3 handling. ([6/9]) - preempt_check debug function also is involved in int3 handling. ([7/9]) - RCU debug routine is also called before kprobe_int3_handler(). ([8/9]) - Some lockdep functions are also involved in int3 handling. ([9/9]) Of course there still may be some functions which can be called by configuration change, I'll continue to test it. Thank you, --- Masami Hiramatsu (9): x86/kprobes: Prohibit probing on optprobe template code x86/kprobes: Move trampoline code into RODATA x86/kprobes: Prohibit probing on functions before kprobe_int3_handler() x86/kprobes: Prohibit probing on IRQ handlers directly kprobes: Search non-suffixed symbol in blacklist kprobes: Prohibit probing on hardirq tracers kprobes: Prohibit probing on preempt_check debug functions kprobes: Prohibit probing on RCU debug routine kprobes: Prohibit probing on lockdep functions arch/x86/kernel/alternative.c | 3 ++- arch/x86/kernel/ftrace.c | 3 ++- arch/x86/kernel/kprobes/core.c | 7 +++++++ arch/x86/kernel/kprobes/opt.c | 4 ++-- arch/x86/kernel/traps.c | 1 + kernel/kprobes.c | 21 ++++++++++++++++++++- kernel/locking/lockdep.c | 7 ++++++- kernel/rcu/tree.c | 2 ++ kernel/rcu/update.c | 2 ++ kernel/trace/trace_irqsoff.c | 9 +++++++-- kernel/trace/trace_preemptirq.c | 5 +++++ lib/smp_processor_id.c | 7 +++++-- 12 files changed, 61 insertions(+), 10 deletions(-) -- Masami Hiramatsu (Linaro)