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 3D927C2D0CE for ; Tue, 21 Jan 2020 17:32:59 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CB46A206A2 for ; Tue, 21 Jan 2020 17:32:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB46A206A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 482Fx431mWzDqY0 for ; Wed, 22 Jan 2020 04:32:56 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=134.134.136.100; helo=mga07.intel.com; envelope-from=alexey.budankov@linux.intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.intel.com Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 482Fv647CzzDq9C for ; Wed, 22 Jan 2020 04:31:13 +1100 (AEDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Jan 2020 09:31:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,346,1574150400"; d="scan'208";a="221768046" Received: from linux.intel.com ([10.54.29.200]) by fmsmga008.fm.intel.com with ESMTP; 21 Jan 2020 09:31:04 -0800 Received: from [10.252.13.111] (iganakov-mobl1.ger.corp.intel.com [10.252.13.111]) by linux.intel.com (Postfix) with ESMTP id 874B25803C5; Tue, 21 Jan 2020 09:30:55 -0800 (PST) Subject: Re: [PATCH v5 01/10] capabilities: introduce CAP_PERFMON to kernel and user space To: Stephen Smalley , Peter Zijlstra , Arnaldo Carvalho de Melo , Ingo Molnar , "jani.nikula@linux.intel.com" , "joonas.lahtinen@linux.intel.com" , "rodrigo.vivi@intel.com" , "benh@kernel.crashing.org" , Paul Mackerras , Michael Ellerman , "james.bottomley@hansenpartnership.com" , Serge Hallyn , James Morris , Will Deacon , Mark Rutland , Robert Richter , Alexei Starovoitov References: <0548c832-7f4b-dc4c-8883-3f2b6d351a08@linux.intel.com> <9b77124b-675d-5ac7-3741-edec575bd425@linux.intel.com> <64cab472-806e-38c4-fb26-0ffbee485367@tycho.nsa.gov> From: Alexey Budankov Organization: Intel Corp. Message-ID: <05297eff-8e14-ccdf-55a4-870c64516de8@linux.intel.com> Date: Tue, 21 Jan 2020 20:30:54 +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: <64cab472-806e-38c4-fb26-0ffbee485367@tycho.nsa.gov> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Song Liu , Andi Kleen , "linux-parisc@vger.kernel.org" , Alexander Shishkin , "linuxppc-dev@lists.ozlabs.org" , "intel-gfx@lists.freedesktop.org" , Igor Lubashev , linux-kernel , Stephane Eranian , "linux-perf-users@vger.kernel.org" , "selinux@vger.kernel.org" , "linux-security-module@vger.kernel.org" , oprofile-list@lists.sf.net, Lionel Landwerlin , Namhyung Kim , Thomas Gleixner , Jiri Olsa , linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 21.01.2020 17:43, Stephen Smalley wrote: > On 1/20/20 6:23 AM, Alexey Budankov wrote: >> >> Introduce CAP_PERFMON capability designed to secure system performance >> monitoring and observability operations so that CAP_PERFMON would assist >> CAP_SYS_ADMIN capability in its governing role for perf_events, i915_perf >> and other performance monitoring and observability subsystems. >> >> CAP_PERFMON intends to harden system security and integrity during system >> performance monitoring and observability operations by decreasing attack >> surface that is available to a CAP_SYS_ADMIN privileged process [1]. >> Providing access to system performance monitoring and observability >> operations 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 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 [1] for CAP_SYS_ADMIN: "Note: this capability is >> overloaded; see Notes to kernel developers, below." >> >> Although the software running under CAP_PERFMON can not ensure avoidance >> of related hardware issues, the software can still mitigate these issues >> following the official embargoed hardware issues mitigation procedure [2]. >> The bugs in the software itself could be fixed following the standard >> kernel development process [3] to maintain and harden security of system >> performance monitoring and observability operations. >> >> [1] http://man7.org/linux/man-pages/man7/capabilities.7.html >> [2] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html >> [3] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html >> >> Signed-off-by: Alexey Budankov >> --- >> include/linux/capability.h | 12 ++++++++++++ >> include/uapi/linux/capability.h | 8 +++++++- >> security/selinux/include/classmap.h | 4 ++-- >> 3 files changed, 21 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/capability.h b/include/linux/capability.h >> index ecce0f43c73a..8784969d91e1 100644 >> --- a/include/linux/capability.h >> +++ b/include/linux/capability.h >> @@ -251,6 +251,18 @@ extern bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct >> extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap); >> extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); >> extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns); >> +static inline bool perfmon_capable(void) >> +{ >> + struct user_namespace *ns = &init_user_ns; >> + >> + if (ns_capable_noaudit(ns, CAP_PERFMON)) >> + return ns_capable(ns, CAP_PERFMON); >> + >> + if (ns_capable_noaudit(ns, CAP_SYS_ADMIN)) >> + return ns_capable(ns, CAP_SYS_ADMIN); >> + >> + return false; >> +} > > Why _noaudit()? Normally only used when a permission failure is non-fatal to the operation. Otherwise, we want the audit message. Some of ideas from v4 review. Well, on the second sight, it defenitly should be logged for CAP_SYS_ADMIN. Probably it is not so fatal for CAP_PERFMON, but personally I would unconditionally log it for CAP_PERFMON as well. Good catch, thank you. ~Alexey