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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 98F54C6778F for ; Thu, 26 Jul 2018 22:16:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E5532088E for ; Thu, 26 Jul 2018 22:16:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E5532088E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.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 S1731853AbeGZXev (ORCPT ); Thu, 26 Jul 2018 19:34:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:56082 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730581AbeGZXev (ORCPT ); Thu, 26 Jul 2018 19:34:51 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 76006206B7; Thu, 26 Jul 2018 22:16:01 +0000 (UTC) Date: Thu, 26 Jul 2018 18:15:58 -0400 From: Steven Rostedt To: Nick Desaulniers Cc: greg@kroah.com, Kees Cook , salyzyn@android.com, LKML , mingo@redhat.com, kernel-team@android.com, stable@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [PATCH] tracing: do not leak kernel addresses Message-ID: <20180726181558.25a5c3b8@gandalf.local.home> In-Reply-To: References: <20180725202238.165314-1-salyzyn@android.com> <20180725210717.3b807191@vmware.local.home> <11437c3e-5131-7190-c496-7b51eb7fcc2a@android.com> <20180726153153.GA8327@kroah.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Jul 2018 09:52:11 -0700 Nick Desaulniers wrote: > See the section "Kernel addresses" in > Documentation/security/self-protection. IIRC, the issue is that a > process may have CAP_SYSLOG but not necessarily CAP_SYS_ADMIN (so it > can read dmesg, but not necessarily issue a sysctl to change > kptr_restrict), get compromised and used to leak kernel addresses, > which can then be used to defeat KASLR. But the code doesn't go to dmesg. It's only available via /sys/kernel/debug/tracing/printk_formats which is only available via root. Nobody else has access to that directory. -- Steve