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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 1B4D4C32771 for ; Sat, 18 Jan 2020 18:49:17 +0000 (UTC) Received: from bombadil.infradead.org (unknown [198.137.202.133]) (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 E333624686 for ; Sat, 18 Jan 2020 18:49:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PzqyVRy4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E333624686 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jdr1xgVjrJvZAibMhgZXlfkM9A5MkQfssRZb+pIAL8k=; b=PzqyVRy4Ph380Q j4VvOwA0b1D4PAEgYVmXVajGYUKAvX2FtillAxGOGKFCiMhglcuPxr9ptPp/27JRH5mc4vjQNiT1s 37Z9CaR+XgNaF+2HL5zBUCPVD9ngX773+7aGp3errfVt/Ulwnzf6y4feLvb+UrMU2gggZ+0f8sgMS N/5POPUG6fvlj0ZbBBP4QOHfVfpFKcOYnz7sCnNEsLiCMZuSQ/06PRQAJqT2WeI2bwqP3ISmf28gC IZN9UOn8pn3B1hon5K73jdeVUX21iAuLbyUMupp1GFeHPSEk99/KjHTFPJts3DrsgcDaCRzcQSUj0 K18ws/w/XNFwqN6Wn8+A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ist9C-0001Fg-Ex; Sat, 18 Jan 2020 18:48:38 +0000 Received: from mga11.intel.com ([192.55.52.93]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ist99-0001FN-6i for linux-arm-kernel@lists.infradead.org; Sat, 18 Jan 2020 18:48:36 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Jan 2020 10:48:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,335,1574150400"; d="scan'208";a="227730994" Received: from linux.intel.com ([10.54.29.200]) by orsmga006.jf.intel.com with ESMTP; 18 Jan 2020 10:48:34 -0800 Received: from [10.252.10.77] (abudanko-mobl.ccr.corp.intel.com [10.252.10.77]) by linux.intel.com (Postfix) with ESMTP id 348F35803DA; Sat, 18 Jan 2020 10:48:25 -0800 (PST) Subject: Re: [PATCH v4 8/9] drivers/perf: open access for CAP_SYS_PERFMON privileged process To: Will Deacon References: <20200117105153.GB6144@willie-the-truck> From: Alexey Budankov Organization: Intel Corp. Message-ID: <63e070c1-413c-efef-ccd6-97e70d8a90d0@linux.intel.com> Date: Sat, 18 Jan 2020 21:48:24 +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: <20200117105153.GB6144@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200118_104835_256489_507FDB4F X-CRM114-Status: GOOD ( 16.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Song Liu , Peter Zijlstra , Benjamin Herrenschmidt , "joonas.lahtinen@linux.intel.com" , Will Deacon , Alexei Starovoitov , Stephane Eranian , "james.bottomley@hansenpartnership.com" , Paul Mackerras , Jiri Olsa , Andi Kleen , Michael Ellerman , Igor Lubashev , James Morris , Alexander Shishkin , Ingo Molnar , Serge Hallyn , Robert Richter , Kees Cook , Jann Horn , "jani.nikula@linux.intel.com" , Arnaldo Carvalho de Melo , "rodrigo.vivi@intel.com" , Namhyung Kim , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, linux-kernel , Casey Schaufler Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 17.01.2020 13:51, Will Deacon wrote: > On Wed, Dec 18, 2019 at 12:30:29PM +0300, Alexey Budankov wrote: >> >> Open access to monitoring for CAP_SYS_PERFMON privileged processes. >> 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_SYS_PERFMON capability. >> >> Signed-off-by: Alexey Budankov >> --- >> drivers/perf/arm_spe_pmu.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> 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)))) > > Acked-by: Will Deacon > > Worth noting that this allows profiling of *physical* addresses used by > memory access instructions and so probably has some security implications > beyond the usual "but perf is buggy" line of reasoning. Good to know. Thank you! The data on physical addresses used by memory access instructions can already be provided under CAP_SYS_ADMIN privileges [1] thus, I suppose, any implications you have mentioned are already in place. I believe providing the data under CAP_PERFMON alone without the rest of CAP_SYS_ADMIN credentials decreases chances to misuse the data for harm and makes the monitoring more secure. ~Alexey [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html > > Will > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel