From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753244AbaGHG7i (ORCPT ); Tue, 8 Jul 2014 02:59:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65281 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753172AbaGHG7g (ORCPT ); Tue, 8 Jul 2014 02:59:36 -0400 Date: Tue, 8 Jul 2014 08:59:01 +0200 From: Jiri Olsa To: Peter Zijlstra Cc: Alexander Yarygin , Arnaldo Carvalho de Melo , Paul Mackerras , Ingo Molnar , Christian Borntraeger , linux-kernel@vger.kernel.org Subject: Re: [BUG] perf stat: events inheritance can break task targets Message-ID: <20140708065901.GA12661@krava.redhat.com> References: <874myt86ju.wl%yarygin@linux.vnet.ibm.com> <20140707170040.GB2070@krava.redhat.com> <20140707194635.GZ6758@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140707194635.GZ6758@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 07, 2014 at 09:46:35PM +0200, Peter Zijlstra wrote: > On Mon, Jul 07, 2014 at 07:00:40PM +0200, Jiri Olsa wrote: > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c > > index 5d12bb4..b44184b 100644 > > --- a/kernel/trace/trace_event_perf.c > > +++ b/kernel/trace/trace_event_perf.c > > @@ -24,6 +24,9 @@ static int total_ref_count; > > static int perf_trace_event_perm(struct ftrace_event_call *tp_event, > > struct perf_event *p_event) > > { > > + struct task_struct owner = p_event->parent ? p_event->parent->owner : > > + p_event->owner; > > + > > if (tp_event->perf_perm) { > > int ret = tp_event->perf_perm(tp_event, p_event); > > if (ret) > > @@ -32,7 +35,7 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event, > > > > /* The ftrace function trace is allowed only for root. */ > > if (ftrace_event_is_function(tp_event)) { > > - if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) > > + if (perf_paranoid_tracepoint_raw() && !has_capability(owner, CAP_SYS_ADMIN)) > > return -EPERM; > > > > /* > > @@ -65,7 +68,7 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event, > > * ...otherwise raw tracepoint data can be a severe data leak, > > * only allow root to have these. > > */ > > - if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) > > + if (perf_paranoid_tracepoint_raw() && !has_capability(owner, CAP_SYS_ADMIN)) > > return -EPERM; > > > > return 0; > > You need to either hold rcu_read_lock() or otherwise ensure the owner is > still valid. ok, I'll resend thanks, jirka