From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758606AbcHDNq0 (ORCPT ); Thu, 4 Aug 2016 09:46:26 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:53524 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752141AbcHDNqY (ORCPT ); Thu, 4 Aug 2016 09:46:24 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: aravinda@linux.vnet.ibm.com Subject: Re: [RFC PATCH v2 2/3] tracefs: add instances support for uprobe events To: Steven Rostedt References: <146965470618.23765.7329786743211962695.stgit@hbathini.in.ibm.com> <146965485827.23765.14920656474693831799.stgit@hbathini.in.ibm.com> <20160801174546.0453ab85@gandalf.local.home> <17cdf475-e663-2ade-d69f-91440d654e98@linux.vnet.ibm.com> <20160802134935.2be2a06a@gandalf.local.home> <57A2466B.1080200@linux.vnet.ibm.com> <20160803161039.3180f0fd@gandalf.local.home> <57A25104.7040805@linux.vnet.ibm.com> <20160803210455.0473467d@grimm.local.home> Cc: Hari Bathini , daniel@iogearbox.net, peterz@infradead.org, linux-kernel@vger.kernel.org, acme@kernel.org, alexander.shishkin@linux.intel.com, mingo@redhat.com, paulus@samba.org, ebiederm@xmission.com, kernel@kyup.com, viro@zeniv.linux.org.uk, ananth@in.ibm.com From: Aravinda Prasad Date: Thu, 4 Aug 2016 19:16:03 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <20160803210455.0473467d@grimm.local.home> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16080413-0008-0000-0000-000005397E1B X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00005547; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000178; SDB=6.00739899; UDB=6.00347931; IPR=6.00512496; BA=6.00004644; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00012152; XFM=3.00000011; UTC=2016-08-04 13:46:22 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16080413-0009-0000-0000-000039F238F6 Message-Id: <57A3471B.4080100@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-04_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1608040153 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 04 August 2016 06:34 AM, Steven Rostedt wrote: > On Thu, 4 Aug 2016 01:46:04 +0530 > Aravinda Prasad wrote: > >> On Thursday 04 August 2016 01:40 AM, Steven Rostedt wrote: >>> On Thu, 4 Aug 2016 01:00:51 +0530 >>> Aravinda Prasad wrote: >>> >>>> >>>>> Can a container have its own function tracing? >>>> >>>> Sorry, I didn't understand that. Do you mean to have a separate >>>> per-container trace files? >>> >>> Actually, it's more my ignorance of containers, as I haven't had the >>> need to play with them. Although, I think it may be time to do so. >>> >>> When a container enters kernel mode, I'm assuming that it's part of the >>> host at that moment, and the host needs to take care of separating >>> everything? That is, there's not a "second kernel" like VMs have, right? >> >> Yes. The host needs to take care of separating everything. There is no >> "second kernel". > > That's what I figured. Thus, my worry is that something like the > function tracer can cause information leak to a container. Yes and thus function tracer is currently disabled inside container unless it is a privileged container. > How would > you separate functions for the container from functions for the host? Separation is based on the context in which the function is called. Hence, containers can see only those kernel functions that are triggered/invoked by the processes running inside that container and should not see other kernel functions, for example, called by RCU grace period kthread or any other kthread. Regards, Aravinda > > -- Steve > -- Regards, Aravinda