From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933704Ab3HGViu (ORCPT ); Wed, 7 Aug 2013 17:38:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40162 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933374Ab3HGVit (ORCPT ); Wed, 7 Aug 2013 17:38:49 -0400 Date: Wed, 7 Aug 2013 14:40:10 -0700 From: Greg Kroah-Hartman To: Bob Smith Cc: Arnd Bergmann , linux-kernel@vger.kernel.org Subject: Re: [PATCH 001/001] CHAR DRIVERS: a simple device to give daemons a /sys-like interface Message-ID: <20130807214010.GA5902@kroah.com> References: <20130803223828.GA14611@kroah.com> <51FECDA6.5070001@linuxtoys.org> <20130804231958.GA25418@kroah.com> <52003958.7080103@linuxtoys.org> <20130806094604.GE27889@kroah.com> <520299AB.1020607@linuxtoys.org> <20130807192714.GC2708@kroah.com> <5202A284.7010106@linuxtoys.org> <20130807195427.GB4121@kroah.com> <5202BC11.6040605@linuxtoys.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5202BC11.6040605@linuxtoys.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 07, 2013 at 02:28:49PM -0700, Bob Smith wrote: > Greg Kroah-Hartman wrote: > > You ignored my mknod comment. > Yes, proxy is a type of IPC. It's closest counterpart in the > kernel now is a named pipe. The kernel does not try to create > named pipes automatically. Named pipes are created deliberately > by users with the mkfifo command or system call. Same with proxy. > The proxy device nodes are application specific and need to be > created as needed by applications. But applications do not have the permissions in a system to create device nodes. Nor should they need that permission. > Allocation of minor numbers is an issue but that is an issue that > is separate from the proxy module itself. How is it separate, it seems tied directly to it as something that must be handled properly. > > Also, no, setting the permissions like this is not ok for a real system, > > what is going to be in charge of setting the permissions on these random > > device nodes? > Again, compare proxy to a named pipe. It is up the application > writer to decide who gets read and write access to its proxy > nodes. Ok, but to do so, you have to have root permissions to start with, which is generally not going to happen on sane systems. Only allowing root access to this seems like a huge limitation. thanks, greg k-h