From patchwork Mon Feb 17 08:08:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Budankov X-Patchwork-Id: 11385563 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 1E8141820 for ; Mon, 17 Feb 2020 08:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00D6C208C4 for ; Mon, 17 Feb 2020 08:08:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727815AbgBQIIW (ORCPT ); Mon, 17 Feb 2020 03:08:22 -0500 Received: from mga03.intel.com ([134.134.136.65]:29093 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726996AbgBQIIW (ORCPT ); Mon, 17 Feb 2020 03:08:22 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Feb 2020 00:08:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,451,1574150400"; d="scan'208";a="433715452" Received: from linux.intel.com ([10.54.29.200]) by fmsmga005.fm.intel.com with ESMTP; 17 Feb 2020 00:08:20 -0800 Received: from [10.125.252.180] (abudanko-mobl.ccr.corp.intel.com [10.125.252.180]) by linux.intel.com (Postfix) with ESMTP id B4F435804A2; Mon, 17 Feb 2020 00:08:13 -0800 (PST) Subject: [PATCH v7 04/12] perf tool: extend Perf tool with CAP_PERFMON capability support From: Alexey Budankov To: James Morris , Serge Hallyn , Stephen Smalley , Peter Zijlstra , Arnaldo Carvalho de Melo , Ingo Molnar , "joonas.lahtinen@linux.intel.com" , Alexei Starovoitov , Will Deacon , Paul Mackerras , Helge Deller , Thomas Gleixner Cc: Andi Kleen , Stephane Eranian , Igor Lubashev , Jiri Olsa , linux-kernel , "intel-gfx@lists.freedesktop.org" , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , linux-arm-kernel , "linuxppc-dev@lists.ozlabs.org" , "linux-parisc@vger.kernel.org" , oprofile-list@lists.sf.net, "linux-doc@vger.kernel.org" , linux-man@vger.kernel.org References: Organization: Intel Corp. Message-ID: <5f961a07-36d0-d8f4-1895-6cfc38bcb81e@linux.intel.com> Date: Mon, 17 Feb 2020 11:08:12 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@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. 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 Reviewed-by: James Morris --- 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 c8dc4450884c..da57d1d4c601 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -2493,14 +2493,14 @@ 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; }