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, USER_AGENT_SANE_1 autolearn=unavailable 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 017C6C33CB3 for ; Tue, 28 Jan 2020 21:20:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D47AA24683 for ; Tue, 28 Jan 2020 21:20:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726446AbgA1VUr (ORCPT ); Tue, 28 Jan 2020 16:20:47 -0500 Received: from namei.org ([65.99.196.166]:60556 "EHLO namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726211AbgA1VUr (ORCPT ); Tue, 28 Jan 2020 16:20:47 -0500 Received: from localhost (localhost [127.0.0.1]) by namei.org (8.14.4/8.14.4) with ESMTP id 00SLI4pL004594; Tue, 28 Jan 2020 21:18:04 GMT Date: Wed, 29 Jan 2020 08:18:04 +1100 (AEDT) From: James Morris To: Alexey Budankov cc: 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 , "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 Subject: Re: [PATCH v6 09/10] drivers/perf: open access for CAP_PERFMON privileged process In-Reply-To: Message-ID: References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Tue, 28 Jan 2020, Alexey Budankov wrote: > > Open access to monitoring for CAP_PERFMON privileged process. > Providing the access under CAP_PERFMON capability singly, without the > rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the > credentials and makes operation more secure. > > 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 the monitoring remains open > for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for secure > monitoring is discouraged with respect to CAP_PERFMON capability. > > Signed-off-by: Alexey Budankov > --- > drivers/perf/arm_spe_pmu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > Acked-by: James Morris > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 4e4984a55cd1..5dff81bc3324 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -274,7 +274,7 @@ static u64 arm_spe_event_to_pmscr(struct perf_event *event) > if (!attr->exclude_kernel) > reg |= BIT(SYS_PMSCR_EL1_E1SPE_SHIFT); > > - if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && capable(CAP_SYS_ADMIN)) > + if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && perfmon_capable()) > reg |= BIT(SYS_PMSCR_EL1_CX_SHIFT); > > return reg; > @@ -700,7 +700,7 @@ static int arm_spe_pmu_event_init(struct perf_event *event) > return -EOPNOTSUPP; > > reg = arm_spe_event_to_pmscr(event); > - if (!capable(CAP_SYS_ADMIN) && > + if (!perfmon_capable() && > (reg & (BIT(SYS_PMSCR_EL1_PA_SHIFT) | > BIT(SYS_PMSCR_EL1_CX_SHIFT) | > BIT(SYS_PMSCR_EL1_PCT_SHIFT)))) > -- James Morris