From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH resend] mmc: Added ioctl to let userspace apps send ACMDs Date: Fri, 18 Mar 2011 20:26:48 +0100 Message-ID: <201103182026.48939.arnd@arndb.de> References: <203F41F6E33F954E8E8B02559FDC906F7431FC48EA@modex01> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-2 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from moutng.kundenserver.de ([212.227.126.186]:52874 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756898Ab1CRT0x (ORCPT ); Fri, 18 Mar 2011 15:26:53 -0400 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: =?iso-8859-2?q?Micha=B3_Miros=B3aw?= Cc: John Calixto , linux-mmc@vger.kernel.org, cjb@laptop.org On Friday 18 March 2011 18:56:53 Micha=B3 Miros=B3aw wrote: > If that's going to be used by possibly unprivileged userspace process= , > then this passthrough should filter and validate all commands it > passes to hardware. If there is a possibility of some command sequenc= e > to generate undefined or otherwise unwanted results, then you need > state tracker that will disallow that sequence to be generated by > unprivileged process. We have precedence for direct host commands in a few other block drivers. In general, any user who can open the block device can issue all commands unless they can directly destroy the hardware. On normal systems, the only user that has write access to block devices is root. Arnd