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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 9E3A7C43441 for ; Sun, 25 Nov 2018 19:47:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 633D32084E for ; Sun, 25 Nov 2018 19:47:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 633D32084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lwn.net 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 S1726550AbeKZGjW (ORCPT ); Mon, 26 Nov 2018 01:39:22 -0500 Received: from ms.lwn.net ([45.79.88.28]:57918 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725863AbeKZGjW (ORCPT ); Mon, 26 Nov 2018 01:39:22 -0500 Received: from lwn.net (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 7FD2497E; Sun, 25 Nov 2018 19:47:33 +0000 (UTC) Date: Sun, 25 Nov 2018 12:47:32 -0700 From: Jonathan Corbet To: Alexey Budankov Cc: Thomas Gleixner , Kees Cook , Jann Horn , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Andi Kleen , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Mark Rutland , Tvrtko Ursulin , linux-kernel , "kernel-hardening@lists.openwall.com" , "linux-doc@vger.kernel.org" Subject: Re: [PATCH v2 1/2] Documentation/admin-guide: introduce perf-security.rst file Message-ID: <20181125124732.6c1807de@lwn.net> In-Reply-To: <4d95341d-d1f4-fc48-f173-a6fedfc70d33@linux.intel.com> References: <259a9cd2-5c56-4f8d-57c4-cabaeaa774bc@linux.intel.com> <4d95341d-d1f4-fc48-f173-a6fedfc70d33@linux.intel.com> Organization: LWN.net MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 21 Nov 2018 12:14:14 +0300 Alexey Budankov wrote: > +For the purpose of performing security checks Linux implementation splits > +processes into two categories [6]_ : a) privileged processes (whose effective > +user ID is 0, referred to as superuser or root), and b) unprivileged processes > +(whose effective UID is nonzero). Is that really what's going on here? If I understand things correctly, it's looking for CAP_SYS_PTRACE rather than a specific UID; am I missing something here? (Also, you would want "*the* Linux implementation" in the first sentence above). One other thing: > +(whose effective UID is nonzero). Privileged processes bypass all kernel > +security permission checks so perf_events performance monitoring is fully > +available to privileged processes without *access*, *scope* and *resource* > +restrictions. Could I ask for a slight toning down of the markup here? There's a lot of *emphasis* here that isn't really needed and tends to get in the way. Thanks, jon