From patchwork Wed Dec 18 09:16:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Budankov X-Patchwork-Id: 11300051 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 6D776921 for ; Wed, 18 Dec 2019 09:18:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B4D7227BF for ; Wed, 18 Dec 2019 09:18:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726846AbfLRJRK (ORCPT ); Wed, 18 Dec 2019 04:17:10 -0500 Received: from mga18.intel.com ([134.134.136.126]:60669 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725955AbfLRJRK (ORCPT ); Wed, 18 Dec 2019 04:17:10 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Dec 2019 01:17:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,328,1571727600"; d="scan'208";a="205782211" Received: from linux.intel.com ([10.54.29.200]) by orsmga007.jf.intel.com with ESMTP; 18 Dec 2019 01:17:08 -0800 Received: from [10.125.252.219] (abudanko-mobl.ccr.corp.intel.com [10.125.252.219]) by linux.intel.com (Postfix) with ESMTP id 0400D5802C9; Wed, 18 Dec 2019 01:16:59 -0800 (PST) From: Alexey Budankov Subject: [PATCH v4 0/7] Introduce CAP_SYS_PERFMON to secure system performance monitoring and observability To: Peter Zijlstra , Arnaldo Carvalho de Melo , Ingo Molnar , "jani.nikula@linux.intel.com" , "joonas.lahtinen@linux.intel.com" , "rodrigo.vivi@intel.com" , Alexei Starovoitov , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , "james.bottomley@hansenpartnership.com" , Serge Hallyn , James Morris , Will Deacon , Mark Rutland , Casey Schaufler , Robert Richter Cc: Jiri Olsa , Andi Kleen , Stephane Eranian , Igor Lubashev , Alexander Shishkin , Namhyung Kim , Kees Cook , Jann Horn , Thomas Gleixner , Tvrtko Ursulin , Lionel Landwerlin , Song Liu , linux-kernel , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , "intel-gfx@lists.freedesktop.org" , "bpf@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-perf-users@vger.kernel.org" , linux-arm-kernel@lists.infradead.org, oprofile-list@lists.sf.net Organization: Intel Corp. Message-ID: Date: Wed, 18 Dec 2019 12:16:58 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 Content-Language: en-US Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org Currently access to perf_events, i915_perf and other performance monitoring and observability subsystems of the kernel is open for a privileged process [1] with CAP_SYS_ADMIN capability enabled in the process effective set [2]. This patch set introduces CAP_SYS_PERFMON capability devoted to secure system performance monitoring and observability operations so that CAP_SYS_PERFMON would assist CAP_SYS_ADMIN capability in its governing role for perf_events, i915_perf and other performance monitoring and observability subsystems of the kernel. CAP_SYS_PERFMON intends to meet the demand to secure system performance monitoring and observability operations in security sensitive, restricted, production environments (e.g. HPC clusters, cloud and virtual compute environments) where root or CAP_SYS_ADMIN credentials are not available to mass users of a system because of security considerations. CAP_SYS_PERFMON intends to harden system security and integrity during system performance monitoring and observability operations by decreasing attack surface that is available to CAP_SYS_ADMIN privileged processes [2]. CAP_SYS_PERFMON intends to take over CAP_SYS_ADMIN credentials related to system performance monitoring and observability operations and balance amount of CAP_SYS_ADMIN credentials following the recommendations in the capabilities man page [2] for CAP_SYS_ADMIN: "Note: this capability is overloaded; see Notes to kernel developers, below." For backward compatibility reasons access to system performance monitoring and observability subsystems of the kernel remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN capability usage for secure system performance monitoring and observability operations is discouraged with respect to the introduced CAP_SYS_PERFMON capability. The patch set is for tip perf/core repository: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip perf/core sha1: ceb9e77324fa661b1001a0ae66f061b5fcb4e4e6 --- Changes in v4: - converted perfmon_capable() into an inline function - made perf_events kprobes, uprobes, hw breakpoints and namespaces data available to CAP_SYS_PERFMON privileged processes - applied perfmon_capable() to drivers/perf and drivers/oprofile - extended __cmd_ftrace() with support of CAP_SYS_PERFMON Changes in v3: - implemented perfmon_capable() macros aggregating required capabilities checks Changes in v2: - made perf_events trace points available to CAP_SYS_PERFMON privileged processes - made perf_event_paranoid_check() treat CAP_SYS_PERFMON equally to CAP_SYS_ADMIN - applied CAP_SYS_PERFMON to i915_perf, bpf_trace, powerpc and parisc system performance monitoring and observability related subsystems --- Alexey Budankov (9): capabilities: introduce CAP_SYS_PERFMON to kernel and user space perf/core: open access for CAP_SYS_PERFMON privileged process perf tool: extend Perf tool with CAP_SYS_PERFMON capability support drm/i915/perf: open access for CAP_SYS_PERFMON privileged process trace/bpf_trace: open access for CAP_SYS_PERFMON privileged process powerpc/perf: open access for CAP_SYS_PERFMON privileged process parisc/perf: open access for CAP_SYS_PERFMON privileged process drivers/perf: open access for CAP_SYS_PERFMON privileged process drivers/oprofile: open access for CAP_SYS_PERFMON privileged process arch/parisc/kernel/perf.c | 2 +- arch/powerpc/perf/imc-pmu.c | 4 ++-- drivers/gpu/drm/i915/i915_perf.c | 13 ++++++------- drivers/oprofile/event_buffer.c | 2 +- drivers/perf/arm_spe_pmu.c | 4 ++-- include/linux/capability.h | 4 ++++ include/linux/perf_event.h | 6 +++--- include/uapi/linux/capability.h | 8 +++++++- kernel/events/core.c | 6 +++--- kernel/trace/bpf_trace.c | 2 +- security/selinux/include/classmap.h | 4 ++-- 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 + 16 files changed, 47 insertions(+), 31 deletions(-) --- Testing and validation (Intel Skylake, 8 cores, Fedora 29, 5.4.0-rc8+, x86_64): libcap library [3], [4] and Perf tool can be used to apply CAP_SYS_PERFMON capability for secure system performance monitoring and observability beyond the scope permitted by the system wide perf_event_paranoid kernel setting [5] and below are the steps for evaluation: - patch, build and boot the kernel - patch, build Perf tool e.g. to /home/user/perf ... # git clone git://git.kernel.org/pub/scm/libs/libcap/libcap.git libcap # pushd libcap # patch libcap/include/uapi/linux/capabilities.h with [PATCH 1] # make # pushd progs # ./setcap "cap_sys_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf # ./setcap -v "cap_sys_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf /home/user/perf: OK # ./getcap /home/user/perf /home/user/perf = cap_sys_ptrace,cap_syslog,cap_sys_perfmon+ep # echo 2 > /proc/sys/kernel/perf_event_paranoid # cat /proc/sys/kernel/perf_event_paranoid 2 ... $ /home/user/perf top ... works as expected ... $ cat /proc/`pidof perf`/status Name: perf Umask: 0002 State: S (sleeping) Tgid: 2958 Ngid: 0 Pid: 2958 PPid: 9847 TracerPid: 0 Uid: 500 500 500 500 Gid: 500 500 500 500 FDSize: 256 ... CapInh: 0000000000000000 CapPrm: 0000004400080000 CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 cap_sys_perfmon,cap_sys_ptrace,cap_syslog CapBnd: 0000007fffffffff CapAmb: 0000000000000000 NoNewPrivs: 0 Seccomp: 0 Speculation_Store_Bypass: thread vulnerable Cpus_allowed: ff Cpus_allowed_list: 0-7 ... Usage of cap_sys_perfmon effectively avoids unused credentials excess: - with cap_sys_admin: CapEff: 0000007fffffffff => 01111111 11111111 11111111 11111111 11111111 - with cap_sys_perfmon: CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 38 34 19 sys_perfmon syslog sys_ptrace --- [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html [2] http://man7.org/linux/man-pages/man7/capabilities.7.html [3] http://man7.org/linux/man-pages/man8/setcap.8.html [4] https://git.kernel.org/pub/scm/libs/libcap/libcap.git [5] http://man7.org/linux/man-pages/man2/perf_event_open.2.html [6] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf