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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D05D5C76190 for ; Thu, 25 Jul 2019 19:11:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A74C9229F9 for ; Thu, 25 Jul 2019 19:11:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="k6oy9kzv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726444AbfGYTLb (ORCPT ); Thu, 25 Jul 2019 15:11:31 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33104 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726065AbfGYTLa (ORCPT ); Thu, 25 Jul 2019 15:11:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=NZgArJ4A0rpRQ2joOKkTtaW1dVOFPQo4qCltbvtRjM0=; b=k6oy9kzv+K54qnV0e8oy+G/G+ 1D2KwDE/vwlTF/3p+8yfyLo5EYeB5rWN7JTp/UCF5yw8ni5L76UvzuQp7ukje5XUPRDiX+Odgz5sf PN9Rjw8eL0qYyLSCy/nX6alOZy3oFHlWDt3MTE2kyU86O0PL6nuQkDXJS0CJoC0ffOVm0pkVe5687 LXpoSDmF4mHpFgp8FtWIewV7cTVpNEFVJLLm9Ivg00/D4nuJSBcsX1vgCAkyGoiSPyFFFO1tqGYIN 9g9HwW+d/0J0Zy7HB6HtHV+biDDu/DX7tsSA1TbElJ0S/I3CaP/9v477akFFDlHppKjEsbuOq2Wsg DmLS72UuQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hqj9B-0005NS-Ma; Thu, 25 Jul 2019 19:11:25 +0000 Date: Thu, 25 Jul 2019 12:11:25 -0700 From: Matthew Wilcox To: Sagi Grimberg Cc: Greg Kroah-Hartman , Jens Axboe , Chaitanya Kulkarni , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, Keith Busch , Alexander Viro , linux-fsdevel@vger.kernel.org, Max Gurtovoy , Logan Gunthorpe , Christoph Hellwig Subject: Re: [PATCH v6 02/16] chardev: introduce cdev_get_by_path() Message-ID: <20190725191124.GE30641@bombadil.infradead.org> References: <20190725172335.6825-1-logang@deltatee.com> <20190725172335.6825-3-logang@deltatee.com> <20190725174032.GA27818@kroah.com> <682ff89f-04e0-7a94-5aeb-895ac65ee7c9@deltatee.com> <20190725180816.GA32305@kroah.com> <20190725182701.GA11547@kroah.com> <20190725190024.GD30641@bombadil.infradead.org> <27943e06-a503-162e-356b-abb9e106ab2e@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27943e06-a503-162e-356b-abb9e106ab2e@grimberg.me> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jul 25, 2019 at 12:05:29PM -0700, Sagi Grimberg wrote: > > > > > NVMe-OF is configured using configfs. The target is specified by the > > > > user writing a path to a configfs attribute. This is the way it works > > > > today but with blkdev_get_by_path()[1]. For the passthru code, we need > > > > to get a nvme_ctrl instead of a block_device, but the principal is the same. > > > > > > Why isn't a fd being passed in there instead of a random string? > > > > I suppose we could echo a string of the file descriptor number there, > > and look up the fd in the process' file descriptor table ... > > Assuming that there is a open handle somewhere out there... Well, that's how we'd know that the application echoing /dev/nvme3 into configfs actually has permission to access /dev/nvme3. Think about containers, for example. It's not exactly safe to mount configfs in a non-root container since it can access any NVMe device in the system, not just ones which it's been given permission to access. Right?