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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 8A890C2BB85 for ; Tue, 7 Apr 2020 14:30:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 615112072A for ; Tue, 7 Apr 2020 14:30:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lditmRVv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729071AbgDGOaT (ORCPT ); Tue, 7 Apr 2020 10:30:19 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:40376 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728573AbgDGOaT (ORCPT ); Tue, 7 Apr 2020 10:30:19 -0400 Received: by mail-qt1-f193.google.com with SMTP id y25so2771046qtv.7; Tue, 07 Apr 2020 07:30:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=wAYrV6F6G+t5gtx1fZuHs6BGJWDWpkiLa+6bzhMBPMw=; b=lditmRVv/LcoROMCq/bKinCSCXK7kSIPrd2WRkQgfMAG5iVrBZ7uZka/PsnKohQP4j 5Ig6xbokfQxWbvrqqOP7Fe0/tljFqjZ80Gbua+AN6PMXq9s4R68pYsgeD7r1Fqj3pNs/ IsJOdPJ5t4WGOqRjC0s5L83yp/k8PHgJatpA0ED1TX7i2eDBvs0ELJvtm9oE+S+iWZcJ bcp4PUVjR/UGlyu0CDmP1DmVV6MGtCGjLpoDfAMr7gwkoH0eoRQKU/i8LwAwcoASeSjp Ylh8TlsWTOmutTIIZ3KXodzQRUC7kb6ikoJSb/vTaeiBtaot8jodWWYa5xiD4kkggAO8 O9Hg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=wAYrV6F6G+t5gtx1fZuHs6BGJWDWpkiLa+6bzhMBPMw=; b=klGKSMdb9pok0vM8+5rEtqTOiArlmHLU+Kve4ocDwdG09FbTaV7Mc27+IeZ9ThwIwX Nvqg6CBbr5FvWTQnJAJjfdq3BHO9i31dfUXKsODLOnWIARszw/rWqCW7xEVAC90C+/OV z5XC40CKpbJZDBKWGkOmSVGzIPIrQHNtpvtelFCtQLofvGzGdY27NEzNTEY2Uf26eJhD XjzFR7dv7MWH/MV/il/gUAU4ObyVS4RE6Ig5+fs3J6GQup3JobAkmZupi0FrZ+F3U1f4 99oX+pjSvCJOg8XuVxWJST7fUdtgObX/x1KPdHLEG8p6mElOM107gPlG/CQQ5F8mjWUC HLjQ== X-Gm-Message-State: AGi0PuZT3gcd9jkFlExgCvwNttPLoWgCnQuz3z/9ObHy1r1/G6rBhkMM 0LDYsa0DQ3YNpp443PnEL8M= X-Google-Smtp-Source: APiQypIGrLW0bPlJckdtYiMlXs17H02JiQkfUDEoX+VYMNZN6nQVg3T1qcLOBfWIiE8HKabTPloJSQ== X-Received: by 2002:aed:29e1:: with SMTP id o88mr2530139qtd.251.1586269817494; Tue, 07 Apr 2020 07:30:17 -0700 (PDT) Received: from quaco.ghostprotocols.net ([179.97.37.151]) by smtp.gmail.com with ESMTPSA id w30sm17976587qtw.21.2020.04.07.07.30.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2020 07:30:16 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 67DAA409A3; Tue, 7 Apr 2020 11:30:14 -0300 (-03) Date: Tue, 7 Apr 2020 11:30:14 -0300 To: Alexey Budankov Cc: Peter Zijlstra , Alexei Starovoitov , Ingo Molnar , James Morris , Namhyung Kim , Serge Hallyn , Jiri Olsa , Song Liu , Andi Kleen , Stephane Eranian , Igor Lubashev , Thomas Gleixner , linux-kernel , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , "intel-gfx@lists.freedesktop.org" , "linux-doc@vger.kernel.org" , linux-man@vger.kernel.org Subject: Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Message-ID: <20200407143014.GD11186@kernel.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Url: http://acmel.wordpress.com Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org Em Thu, Apr 02, 2020 at 11:42:05AM +0300, Alexey Budankov escreveu: > This patch set introduces 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 performance monitoring and observability subsystems of the kernel. So, what am I doing wrong? [perf@five ~]$ type perf perf is hashed (/home/perf/bin/perf) [perf@five ~]$ [perf@five ~]$ ls -lahF /home/perf/bin/perf -rwxr-x---. 1 root perf_users 24M Apr 7 10:34 /home/perf/bin/perf* [perf@five ~]$ [perf@five ~]$ getcap /home/perf/bin/perf [perf@five ~]$ perf top --stdio Error: You may not have permission to collect system-wide stats. Consider tweaking /proc/sys/kernel/perf_event_paranoid, which controls use of the performance events system by unprivileged users (without CAP_PERFMON or CAP_SYS_ADMIN). The current value is 2: -1: Allow use of (almost) all events by all users Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK >= 0: Disallow ftrace function tracepoint by users without CAP_PERFMON or CAP_SYS_ADMIN Disallow raw tracepoint access by users without CAP_SYS_PERFMON or CAP_SYS_ADMIN >= 1: Disallow CPU event access by users without CAP_PERFMON or CAP_SYS_ADMIN >= 2: Disallow kernel profiling by users without CAP_PERFMON or CAP_SYS_ADMIN To make this setting permanent, edit /etc/sysctl.conf too, e.g.: kernel.perf_event_paranoid = -1 [perf@five ~]$ Ok, the message says I need to have CAP_PERFMON, lets do it, using an unpatched libcap that doesn't know about it but we can use 38, CAP_PERFMON value instead, and I tested this with a patched libcap as well, same results: As root: [root@five bin]# setcap "38,cap_sys_ptrace,cap_syslog=ep" perf [root@five bin]# Back to the 'perf' user in the 'perf_users' group, ok, so now 'perf record -a' works for system wide sampling of cycles:u, i.e. only userspace samples, but 'perf top' is failing: [perf@five ~]$ type perf perf is hashed (/home/perf/bin/perf) [perf@five ~]$ getcap /home/perf/bin/perf /home/perf/bin/perf = cap_sys_ptrace,cap_syslog,38+ep [perf@five ~]$ groups perf perf_users [perf@five ~]$ id uid=1002(perf) gid=1002(perf) groups=1002(perf),1003(perf_users) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [perf@five ~]$ perf top --stdio Error: Failed to mmap with 1 (Operation not permitted) [perf@five ~]$ perf record -a ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.177 MB perf.data (1552 samples) ] [perf@five ~]$ perf evlist cycles:u [perf@five ~]$ - Arnaldo