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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 22537C282DD for ; Fri, 10 Jan 2020 17:37:04 +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 98E5620678 for ; Fri, 10 Jan 2020 17:37:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98E5620678 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 47vVXr5jbSzDqhn for ; Sat, 11 Jan 2020 04:37:00 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=192.55.52.88; helo=mga01.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 mga01.intel.com (mga01.intel.com [192.55.52.88]) (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 47vVVJ4XgXzDqd2 for ; Sat, 11 Jan 2020 04:34:47 +1100 (AEDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Jan 2020 09:34:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,417,1571727600"; d="scan'208";a="216736137" Received: from linux.intel.com ([10.54.29.200]) by orsmga008.jf.intel.com with ESMTP; 10 Jan 2020 09:34:44 -0800 Received: from [10.252.24.8] (abudanko-mobl.ccr.corp.intel.com [10.252.24.8]) by linux.intel.com (Postfix) with ESMTP id A1D7F58045A; Fri, 10 Jan 2020 09:34:34 -0800 (PST) Subject: Re: [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process To: Peter Zijlstra References: <20200108160713.GI2844@hirez.programming.kicks-ass.net> <20200110140234.GO2844@hirez.programming.kicks-ass.net> From: Alexey Budankov Organization: Intel Corp. Message-ID: <603c4d4f-9021-a8bc-1be6-3654d5c557d4@linux.intel.com> Date: Fri, 10 Jan 2020 20:34:33 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200110140234.GO2844@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: Mark Rutland , Song Liu , Alexander Shishkin , "joonas.lahtinen@linux.intel.com" , Will Deacon , Alexei Starovoitov , Stephane Eranian , "james.bottomley@hansenpartnership.com" , Paul Mackerras , Jiri Olsa , Andi Kleen , Igor Lubashev , James Morris , Ingo Molnar , oprofile-list@lists.sf.net, Serge Hallyn , Robert Richter , Kees Cook , Jann Horn , "selinux@vger.kernel.org" , "intel-gfx@lists.freedesktop.org" , "jani.nikula@linux.intel.com" , Arnaldo Carvalho de Melo , "rodrigo.vivi@intel.com" , Namhyung Kim , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Tvrtko Ursulin , "linux-parisc@vger.kernel.org" , linux-kernel , Lionel Landwerlin , "linux-perf-users@vger.kernel.org" , "linux-security-module@vger.kernel.org" , mhiramat@kernel.org, Casey Schaufler , "bpf@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 10.01.2020 17:02, Peter Zijlstra wrote: > On Thu, Jan 09, 2020 at 02:36:50PM +0300, Alexey Budankov wrote: >> On 08.01.2020 19:07, Peter Zijlstra wrote: >>> On Wed, Dec 18, 2019 at 12:25:35PM +0300, Alexey Budankov wrote: > >>>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>>> index 059ee7116008..d9db414f2197 100644 >>>> --- a/kernel/events/core.c >>>> +++ b/kernel/events/core.c >>>> @@ -9056,7 +9056,7 @@ static int perf_kprobe_event_init(struct perf_event *event) >>>> if (event->attr.type != perf_kprobe.type) >>>> return -ENOENT; >>>> >>>> - if (!capable(CAP_SYS_ADMIN)) >>>> + if (!perfmon_capable()) >>>> return -EACCES; >>>> >>>> /* >>> >>> This one only allows attaching to already extant kprobes, right? It does >>> not allow creation of kprobes. >> >> This unblocks creation of local trace kprobes and uprobes by CAP_SYS_PERFMON >> privileged process, exactly the same as for CAP_SYS_ADMIN privileged process. > > I've no idea what you just said; it's just words. > > Again, this only allows attaching to previously created kprobes, it does > not allow creating kprobes, right? Not really, this allows creating a kprobe using perf_event_open syscall that associates file descriptor with the kprobe [1]. Lifetime of that kprobe is equal to the lifetime of the file descriptor and the kprobe is not visible in tracefs: /sys/kernel/debug/tracing/kprobe_events > > That is; I don't think CAP_SYS_PERFMON should be allowed to create > kprobes. > > As might be clear; I don't actually know what the user-ABI is for > creating kprobes. > ~Alexey [1] https://lore.kernel.org/lkml/20171206224518.3598254-1-songliubraving@fb.com/