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 34CFCC43441 for ; Mon, 26 Nov 2018 08:57:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 054A620850 for ; Mon, 26 Nov 2018 08:57:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 054A620850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 S1726308AbeKZTux (ORCPT ); Mon, 26 Nov 2018 14:50:53 -0500 Received: from mga09.intel.com ([134.134.136.24]:20870 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726157AbeKZTuw (ORCPT ); Mon, 26 Nov 2018 14:50:52 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Nov 2018 00:57:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,281,1539673200"; d="scan'208";a="111517504" Received: from linux.intel.com ([10.54.29.200]) by orsmga002.jf.intel.com with ESMTP; 26 Nov 2018 00:57:25 -0800 Received: from [10.125.252.8] (abudanko-mobl.ccr.corp.intel.com [10.125.252.8]) by linux.intel.com (Postfix) with ESMTP id 46CC3580460; Mon, 26 Nov 2018 00:57:22 -0800 (PST) Subject: Re: [PATCH v2 1/2] Documentation/admin-guide: introduce perf-security.rst file To: Jonathan Corbet 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" References: <259a9cd2-5c56-4f8d-57c4-cabaeaa774bc@linux.intel.com> <4d95341d-d1f4-fc48-f173-a6fedfc70d33@linux.intel.com> <20181125124732.6c1807de@lwn.net> From: Alexey Budankov Organization: Intel Corp. Message-ID: <02dbd6dc-86b5-2307-4122-b716c51b9eaa@linux.intel.com> Date: Mon, 26 Nov 2018 11:57:21 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181125124732.6c1807de@lwn.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Jon, On 25.11.2018 22:47, Jonathan Corbet wrote: > 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? You are right regarding CAP_SYS_PTRACE but this capability is not the only one which is used by perf_events for security checks, so the capabilities clarification is kept aside of these patches, because patches initial intention is to clarify security specifics of sysctl_perf_even_paranoid settings. I agree that the document can be extended with details clarifying capabilities used by perf_events for security checks. > > (Also, you would want "*the* Linux implementation" in the first sentence > above). Accepted. > > 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. Accepted. Thanks, Alexey > > Thanks, > > jon >