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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 AF936C433FF for ; Mon, 12 Aug 2019 20:16:04 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [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 74E3720679 for ; Mon, 12 Aug 2019 20:16:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="uZeWloEE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74E3720679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=myeRwS/zfSmtAGzrRMyk5ucsetf4ysglGDfC0CMcmg8=; b=uZeWloEErmTXWt KhMpNWxbrltazeWAidPd7OqXoLOGYGVfJp1MP/uH8ddSUidaTuOf2CYv626GF8Rg5i2VIkA9UE6eg AA2V3kqnEgHdEyA/sxNDTbjYdZl2QXydgbVJe6Qt+1pq1b0h7UeIsmlztSdciHPE4/3uQTG8ToWKo 9ht+kqWCAX+M0FiJtsxKqjfNRtPlELdP8qqhcE8lvVturgXUlnpVxBuUxPmap6MyIMqgzN5sR8M64 aYiGVMkJK/38qvkKDEybZ75NoxmMHLn+IcBtUtWmcuerOxa1/dC1buvCIM4TSdhcqFsDu71X+CEXk /RCJ1KbBTr9Udhlwe43Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hxGjb-0003Ni-91; Mon, 12 Aug 2019 20:16:03 +0000 Received: from 187-26-98-68.3g.claro.net.br ([187.26.98.68] helo=quaco.ghostprotocols.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hxGjY-0003Nb-57; Mon, 12 Aug 2019 20:16:01 +0000 Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 7243E40340; Mon, 12 Aug 2019 17:15:57 -0300 (-03) Date: Mon, 12 Aug 2019 17:15:57 -0300 From: Arnaldo Carvalho de Melo To: Igor Lubashev Subject: Re: [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks Message-ID: <20190812201557.GF9280@kernel.org> References: <20190812200134.GE9280@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190812200134.GE9280@kernel.org> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.12.0 (2019-05-25) 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: Mathieu Poirier , Suzuki K Poulose , Peter Zijlstra , Alexey Budankov , linux-kernel@vger.kernel.org, James Morris , Alexander Shishkin , Ingo Molnar , Namhyung Kim , Jiri Olsa , linux-arm-kernel@lists.infradead.org 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 Em Mon, Aug 12, 2019 at 05:01:34PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Wed, Aug 07, 2019 at 10:44:15AM -0400, Igor Lubashev escreveu: > > +++ b/tools/perf/util/evsel.c > > @@ -279,7 +279,7 @@ struct evsel *perf_evsel__new_idx(struct perf_event_attr *attr, int idx) > > > static bool perf_event_can_profile_kernel(void) > > { > > - return geteuid() == 0 || perf_event_paranoid() == -1; > > + return perf_event_paranoid_check(-1); > > } > > While looking at your changes I think the pre-existing code is wrong, > i.e. the check in sys_perf_event_open(), in the kernel is: > > if (!attr.exclude_kernel) { > if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) > return -EACCES; > } > > And: > > static inline bool perf_paranoid_kernel(void) > { > return sysctl_perf_event_paranoid > 1; > } > > So we have to change that perf_event_paranoit_check(-1) to pass 1 > instead? > > bool perf_event_paranoid_check(int max_level) > { > return perf_cap__capable(CAP_SYS_ADMIN) || > perf_event_paranoid() <= max_level; > } > > Also you defined perf_cap__capable(anything) as: > > #ifdef HAVE_LIBCAP_SUPPORT > > #include > > bool perf_cap__capable(cap_value_t cap); > > #else > > static inline bool perf_cap__capable(int cap __maybe_unused) > { > return false; > } > > #endif /* HAVE_LIBCAP_SUPPORT */ > > > I think we should have: > > #else > > static inline bool perf_cap__capable(int cap __maybe_unused) > { > return geteuid() == 0; > } > > #endif /* HAVE_LIBCAP_SUPPORT */ > > Right? > > So I am removing the introduction of perf_cap__capable() from the first > patch you sent, leaving it with _only_ the feature detection part, using > that feature detection to do anything is then moved to a separate patch, > after we finish this discussion about what we should fallback to when > libcap-devel isn't available, i.e. we should use the previous checks, > etc. So, please take a look at the tmp.perf/cap branch in my git repo: https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.perf/cap I split the patch and made perf_cap__capable() fallback to 'return geteuid() == 0;' when libcap-devel isn't available, i.e. keep the checks made prior to your patchset. Jiri, can I keep your Acked-by? - Arnaldo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel