From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755379AbdKJBBz (ORCPT ); Thu, 9 Nov 2017 20:01:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:37674 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755136AbdKJBBy (ORCPT ); Thu, 9 Nov 2017 20:01:54 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 56298218C5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org Date: Fri, 10 Nov 2017 10:01:50 +0900 From: Masami Hiramatsu To: David Howells Cc: ananth@linux.vnet.ibm.com, alexei.starovoitov@gmail.com, Anil S Keshavamurthy , "David S. Miller" , Masami Hiramatsu , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] Lock down kprobes Message-Id: <20171110100150.ae0062c1bdab4a2f18ddd68c@kernel.org> In-Reply-To: <11786.1510246325@warthog.procyon.org.uk> References: <11786.1510246325@warthog.procyon.org.uk> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, On Thu, 09 Nov 2017 16:52:05 +0000 David Howells wrote: > > Lock down kprobes > > Disallow the creation of kprobes when the kernel is locked down by > preventing their registration. This prevents kprobes from being used to > access kernel memory, either to make modifications or to steal crypto data. Is that locked-down flag changed while running the kernel, or only specified by boot parameter? If that can happen while running, we have to take care of enabling/disabling unregistering etc. too. Thank you, > > Reported-by: Alexei Starovoitov > Signed-off-by: David Howells > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index a1606a4224e1..f06023b0936c 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1530,6 +1530,9 @@ int register_kprobe(struct kprobe *p) > struct module *probed_mod; > kprobe_opcode_t *addr; > > + if (kernel_is_locked_down("Use of kprobes")) > + return -EPERM; > + > /* Adjust probe address from symbol */ > addr = kprobe_addr(p); > if (IS_ERR(addr)) -- Masami Hiramatsu