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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 B59E9C43331 for ; Wed, 1 Apr 2020 20:50:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8553520737 for ; Wed, 1 Apr 2020 20:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733059AbgDAUu0 (ORCPT ); Wed, 1 Apr 2020 16:50:26 -0400 Received: from mga01.intel.com ([192.55.52.88]:15024 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732619AbgDAUu0 (ORCPT ); Wed, 1 Apr 2020 16:50:26 -0400 IronPort-SDR: y95uyv4RLx3QfdXs9mXjuKDz/96+agxYI7IETjYUXy1QxjEn8Js126tQMnx7t6PB5N26avpeHS 9A4DFNAwNRVA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2020 13:50:25 -0700 IronPort-SDR: SktnP5/rzv4X4X/BkvGlMO3MfTk1FyP5XSd4hL5/ap+KdeCvbha09J/+qeyFfqVK6j9mvTcv8Q 68bsfUbHTaqw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,332,1580803200"; d="scan'208";a="240626846" Received: from linux.intel.com ([10.54.29.200]) by fmsmga007.fm.intel.com with ESMTP; 01 Apr 2020 13:50:25 -0700 Received: from [10.213.137.102] (abudanko-MOBL.ccr.corp.intel.com [10.213.137.102]) by linux.intel.com (Postfix) with ESMTP id 537EB58077B; Wed, 1 Apr 2020 13:50:18 -0700 (PDT) Subject: Re: [PATCH v6 04/10] perf tool: extend Perf tool with CAP_PERFMON capability support From: Alexey Budankov To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , Ingo Molnar , Jiri Olsa , Andi Kleen , Igor Lubashev , Alexander Shishkin , Namhyung Kim , James Morris , linux-kernel References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> Organization: Intel Corp. Message-ID: <0c8daba0-bc3c-26bf-e463-b8629403beff@linux.intel.com> Date: Wed, 1 Apr 2020 23:50:16 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: 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 Hi Arnaldo, On 28.01.2020 9:09, Alexey Budankov wrote: > > Extend error messages to mention CAP_PERFMON capability as an option > to substitute CAP_SYS_ADMIN capability for secure system performance > monitoring and observability operations. Make perf_event_paranoid_check() > and __cmd_ftrace() to be aware of CAP_PERFMON capability. > > CAP_PERFMON implements the principal of least privilege for performance > monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39 principle > of least privilege: A security design principle that states that a process > or program be granted only those privileges (e.g., capabilities) necessary > to accomplish its legitimate function, and only for the time that such > privileges are actually required) > > For backward compatibility reasons access to perf_events subsystem remains > open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for > secure perf_events monitoring is discouraged with respect to CAP_PERFMON > capability. > > Signed-off-by: Alexey Budankov > --- > tools/perf/builtin-ftrace.c | 5 +++-- > tools/perf/design.txt | 3 ++- > tools/perf/util/cap.h | 4 ++++ > tools/perf/util/evsel.c | 10 +++++----- > tools/perf/util/util.c | 1 + > 5 files changed, 15 insertions(+), 8 deletions(-) Could this have you explicit Reviewed-by or Acked-by tag so the changes could be driven into the kernel? Latest v7 is here: https://lore.kernel.org/lkml/c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com/ Thanks, Alexey > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index d5adc417a4ca..55eda54240fb 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -284,10 +284,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > .events = POLLIN, > }; > > - if (!perf_cap__capable(CAP_SYS_ADMIN)) { > + if (!(perf_cap__capable(CAP_PERFMON) || > + perf_cap__capable(CAP_SYS_ADMIN))) { > pr_err("ftrace only works for %s!\n", > #ifdef HAVE_LIBCAP_SUPPORT > - "users with the SYS_ADMIN capability" > + "users with the CAP_PERFMON or CAP_SYS_ADMIN capability" > #else > "root" > #endif > diff --git a/tools/perf/design.txt b/tools/perf/design.txt > index 0453ba26cdbd..a42fab308ff6 100644 > --- a/tools/perf/design.txt > +++ b/tools/perf/design.txt > @@ -258,7 +258,8 @@ gets schedule to. Per task counters can be created by any user, for > their own tasks. > > A 'pid == -1' and 'cpu == x' counter is a per CPU counter that counts > -all events on CPU-x. Per CPU counters need CAP_SYS_ADMIN privilege. > +all events on CPU-x. Per CPU counters need CAP_PERFMON or CAP_SYS_ADMIN > +privilege. > > The 'flags' parameter is currently unused and must be zero. > > diff --git a/tools/perf/util/cap.h b/tools/perf/util/cap.h > index 051dc590ceee..ae52878c0b2e 100644 > --- a/tools/perf/util/cap.h > +++ b/tools/perf/util/cap.h > @@ -29,4 +29,8 @@ static inline bool perf_cap__capable(int cap __maybe_unused) > #define CAP_SYSLOG 34 > #endif > > +#ifndef CAP_PERFMON > +#define CAP_PERFMON 38 > +#endif > + > #endif /* __PERF_CAP_H */ > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index a69e64236120..a35f17723dd3 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -2491,14 +2491,14 @@ int perf_evsel__open_strerror(struct evsel *evsel, struct target *target, > "You may not have permission to collect %sstats.\n\n" > "Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n" > "which controls use of the performance events system by\n" > - "unprivileged users (without CAP_SYS_ADMIN).\n\n" > + "unprivileged users (without CAP_PERFMON or CAP_SYS_ADMIN).\n\n" > "The current value is %d:\n\n" > " -1: Allow use of (almost) all events by all users\n" > " Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK\n" > - ">= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN\n" > - " Disallow raw tracepoint access by users without CAP_SYS_ADMIN\n" > - ">= 1: Disallow CPU event access by users without CAP_SYS_ADMIN\n" > - ">= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN\n\n" > + ">= 0: Disallow ftrace function tracepoint by users without CAP_PERFMON or CAP_SYS_ADMIN\n" > + " Disallow raw tracepoint access by users without CAP_SYS_PERFMON or CAP_SYS_ADMIN\n" > + ">= 1: Disallow CPU event access by users without CAP_PERFMON or CAP_SYS_ADMIN\n" > + ">= 2: Disallow kernel profiling by users without CAP_PERFMON or CAP_SYS_ADMIN\n\n" > "To make this setting permanent, edit /etc/sysctl.conf too, e.g.:\n\n" > " kernel.perf_event_paranoid = -1\n" , > target->system_wide ? "system-wide " : "", > diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c > index 969ae560dad9..51cf3071db74 100644 > --- a/tools/perf/util/util.c > +++ b/tools/perf/util/util.c > @@ -272,6 +272,7 @@ int perf_event_paranoid(void) > bool perf_event_paranoid_check(int max_level) > { > return perf_cap__capable(CAP_SYS_ADMIN) || > + perf_cap__capable(CAP_PERFMON) || > perf_event_paranoid() <= max_level; > } > >