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 B1C21C433F4 for ; Sat, 22 Sep 2018 10:21:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57BB421523 for ; Sat, 22 Sep 2018 10:21:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57BB421523 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de 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 S1727634AbeIVQOH (ORCPT ); Sat, 22 Sep 2018 12:14:07 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:41441 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726039AbeIVQOG (ORCPT ); Sat, 22 Sep 2018 12:14:06 -0400 Received: from tmo-109-175.customers.d1-online.com ([80.187.109.175] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1g3f1t-0007Qm-K5; Sat, 22 Sep 2018 12:20:49 +0200 Date: Sat, 22 Sep 2018 12:20:48 +0200 (CEST) From: Thomas Gleixner To: Peter Zijlstra cc: Jiri Kosina , "Schaufler, Casey" , Ingo Molnar , Josh Poimboeuf , Andrea Arcangeli , "Woodhouse, David" , Andi Kleen , Tim Chen , "linux-kernel@vger.kernel.org" , "x86@kernel.org" Subject: Re: [PATCH v6 0/3] Harden spectrev2 userspace-userspace protection In-Reply-To: <20180922101844.GF24124@hirez.programming.kicks-ass.net> Message-ID: References: <99FC4B6EFCEFD44486C35F4C281DC6732144EA58@ORSMSX107.amr.corp.intel.com> <20180919154828.GJ24124@hirez.programming.kicks-ass.net> <20180922101844.GF24124@hirez.programming.kicks-ass.net> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 22 Sep 2018, Peter Zijlstra wrote: > On Sat, Sep 22, 2018 at 11:53:14AM +0200, Thomas Gleixner wrote: > > +bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode) > > +{ > > + struct mm_struct *mm; > > + int res; > > + > > + res = __ptrace_may_access_basic(task, mode); > > + if (res <= 0) > > + return !res; > > + > > + rcu_read_lock(); > > + res = __ptrace_may_access_cred(__task_cred(task), mode); > > rcu_read_unlock(); > > + if (res) > > + return false; > > + > > + mm = task->mm; > > + if (mm && get_dumpable(mm) != SUID_DUMP_USER) > > + return false; > > + return true; > > +} > > + > > +/* Returns 0 on success, -errno on denial. */ > > +static int __ptrace_may_access(struct task_struct *task, unsigned int mode) > > +{ > > + const struct cred *tcred; > > + struct mm_struct *mm; > > + int res; > > + > > + res = __ptrace_may_access_basic(task, mode); > > + if (res <= 0) > > + return res; > > + > > + rcu_read_lock(); > > + tcred = __task_cred(task); > > + res = __ptrace_may_access_cred(tcred, mode); > > + if (res > 0) > > + res = ptrace_has_cap(tcred->user_ns, mode) ? 0 : -EPERM; > > rcu_read_unlock(); > > + if (res < 0) > > + return res; > > + > > mm = task->mm; > > + if (mm && (get_dumpable(mm) != SUID_DUMP_USER && > > + !ptrace_has_cap(mm->user_ns, mode))) > > + return -EPERM; > > > > return security_ptrace_access_check(task, mode); > > } > > This has some unfortunate duplication. > > Lets go with it for now, but I'll see if I can do something about that > later. Yes, I know. I tried to make the duplication smaller, but all attempts ended up being a convoluted mess. I'll try again after applying more coffee. Thanks, tglx