From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZrp2Vm3PMJqz4C9My5SZTZDo4xmO7hbEE0CxurFjBdLD1gYSAnvq5c83eIX4tiGOk7jTrJX ARC-Seal: i=1; a=rsa-sha256; t=1525981491; cv=none; d=google.com; s=arc-20160816; b=mc+TOb4F0/4Kc0t5z5AuYNJ+mXYDEjvw06zMdmvu4WtJcZCyo/BH+eN8+UdYzkj2fE voDZHNCExuRsPTAyMIloTZk8CAesJJoxwYttAo+o240dylsMOw2/XW07KZqultbXOqbQ CpkVK5ZzSmr8sCgACwPO0rvgsrjwF2oSSk8D5Wldyh2ybEjcpsgJkF7x+rORNtZKSlzT 16cSn7fboZLif68fjDCvynGmnG4VQ2yi9WqPkW7Fk3b017hWN2YF0RYeN2PR6FwvyLxc pxrBQoabKGbqeST0Ao++Oz4hOgv0bBrpPdzuf6omRq8dWKoJKnECfQ1wgq38rtqxrI9c cOUw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:user-agent:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=AGl+2Ras8V2s0pKHtlF6LM/9tZk4b0vPr/MfRyErHf8=; b=C8tStQVyqDMSDR2TfygBp/fsNPgSSEwX0Br9/f7Y2f8oePIj9AGvuJR2v8Il9Ta9kg WEGEETvSq9neWt7PXrq8fbndcDrE3hIlHB0/iCI3lcFo3ooMA2dQByJ11qC7UTAfmUyg CMgXxbnLbsdqgZTV5SBkzMm8WQsv8IvbCaxPAalYMaWOOQUtzbkjUhCfdV3c9caad3ry /NsaHI3Oc+m4/HcuOIZdqV9U1YXRVHxF7GrqoxsfZ3tdZUg3CZOsbX8JLnms6cglK0as rfI+jQFyZQt91Ovd+rPd240JZ9n1OzNwqJBpal9D+5awGi1uVjeRi+M+3pndvKHFzzvO NRNA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@armlinux.org.uk header.s=pandora-2014 header.b=MeUiilBM; spf=pass (google.com: best guess record for domain of linux+gregkh=linuxfoundation.org@armlinux.org.uk designates 2001:4d48:ad52:3201:214:fdff:fe10:1be6 as permitted sender) smtp.mailfrom=linux+gregkh=linuxfoundation.org@armlinux.org.uk; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=armlinux.org.uk Authentication-Results: mx.google.com; dkim=pass header.i=@armlinux.org.uk header.s=pandora-2014 header.b=MeUiilBM; spf=pass (google.com: best guess record for domain of linux+gregkh=linuxfoundation.org@armlinux.org.uk designates 2001:4d48:ad52:3201:214:fdff:fe10:1be6 as permitted sender) smtp.mailfrom=linux+gregkh=linuxfoundation.org@armlinux.org.uk; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=armlinux.org.uk Date: Thu, 10 May 2018 20:44:22 +0100 From: Russell King - ARM Linux To: Mathieu Poirier Cc: "Eric W. Biederman" , Kim Phillips , Alexander Shishkin , Alex Williamson , Andrew Morton , David Howells , Eric Auger , Gargi Sharma , Geert Uytterhoeven , Greg Kroah-Hartman , Kefeng Wang , Kirill Tkhai , Mike Rapoport , Oleg Nesterov , Pavel Tatashin , Rik van Riel , Robin Murphy , Thierry Reding , Todd Kjos , linux-arm-kernel , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] pid: Export find_task_by_vpid for use in external modules Message-ID: <20180510194422.GX16141@n2100.armlinux.org.uk> References: <20180508140640.0e312dba025df75cbf205cdb@arm.com> <87d0y5toed.fsf@xmission.com> <20180509152505.GA25559@xps15> <87k1scs0f8.fsf@xmission.com> <20180510084057.GT16141@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: Russell King - ARM Linux X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599923977519130436?= X-GMAIL-MSGID: =?utf-8?q?1600107568651331733?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, May 10, 2018 at 01:39:18PM -0600, Mathieu Poirier wrote: > Hi Russell, > > On 10 May 2018 at 02:40, Russell King - ARM Linux wrote: > > This does not leak information from other namespaces because of the > > uniqueness of the global PID. However, what it does leak is the value > > of the global PID which is meaningless in the namespace. So, before > > the event stream is delivered to userspace, this value needs to be > > re-written to the namespace's PID value. > > Unfortunately that can't be done. The trace stream is compressed and > needs to be decompressed using an external library. I think the only > option is to return an error if a user is trying to use this feature > from a namespace. That sounds like a sensible approach, and that should get rid of the vpid stuff too. Eric, would this solve all your concerns? -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up