From patchwork Tue Jan 28 06:09:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Budankov X-Patchwork-Id: 11353593 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DA3DF1398 for ; Tue, 28 Jan 2020 06:10:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B84962173E for ; Tue, 28 Jan 2020 06:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725776AbgA1GKH (ORCPT ); Tue, 28 Jan 2020 01:10:07 -0500 Received: from mga09.intel.com ([134.134.136.24]:59767 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725774AbgA1GKH (ORCPT ); Tue, 28 Jan 2020 01:10:07 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Jan 2020 22:10:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,372,1574150400"; d="scan'208";a="401566867" Received: from linux.intel.com ([10.54.29.200]) by orsmga005.jf.intel.com with ESMTP; 27 Jan 2020 22:10:05 -0800 Received: from [10.252.25.124] (abudanko-mobl.ccr.corp.intel.com [10.252.25.124]) by linux.intel.com (Postfix) with ESMTP id 7A2B3580277; Mon, 27 Jan 2020 22:09:58 -0800 (PST) Subject: [PATCH v6 04/10] perf tool: extend Perf tool with CAP_PERFMON capability support From: Alexey Budankov To: Peter Zijlstra , Arnaldo Carvalho de Melo , Ingo Molnar , "benh@kernel.crashing.org" , Paul Mackerras , Michael Ellerman , "james.bottomley@hansenpartnership.com" , Serge Hallyn , Will Deacon , Robert Richter , Alexei Starovoitov Cc: "intel-gfx@lists.freedesktop.org" , Jiri Olsa , Andi Kleen , Stephane Eranian , Igor Lubashev , Alexander Shishkin , Namhyung Kim , Song Liu , Lionel Landwerlin , linux-kernel , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , linux-arm-kernel , "linuxppc-dev@lists.ozlabs.org" , "linux-parisc@vger.kernel.org" , "linux-perf-users@vger.kernel.org" , oprofile-list@lists.sf.net References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> Organization: Intel Corp. Message-ID: Date: Tue, 28 Jan 2020 09:09:57 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> Content-Language: en-US Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org 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(-) 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; }