Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754116AbZAFGcl (ORCPT ); Tue, 6 Jan 2009 01:32:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751137AbZAFGcb (ORCPT ); Tue, 6 Jan 2009 01:32:31 -0500 Received: from rv-out-0506.google.com ([209.85.198.234]:4048 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbZAFGcb (ORCPT ); Tue, 6 Jan 2009 01:32:31 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=L+QhsGmpVKKSkD/1v46KZ2UH8rDf1cLWvQQOzy9ySx1ujsmtpExN7W6yweSe4GITXU dWXrDpcRKipq46KLGtnrGELyyDeKSnTjRH0Y2sqzCXYN1BFRDNCE4e6dG4cvVmRYrRVx lSs59G6kmYg7Cx/Py3nEfC+lUr99kQhBvl8BU= Message-ID: <8bd0f97a0901052232l22b60386pbcd9438cc752638f@mail.gmail.com> Date: Tue, 6 Jan 2009 01:32:30 -0500 From: "Mike Frysinger" To: "Greg KH" Subject: Re: debugfs & vfs file permission issue? Cc: "Robin Getz" , viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org In-Reply-To: <20090106061946.GA10026@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200901052157.07306.rgetz@blackfin.uclinux.org> <20090106054858.GA9040@suse.de> <8bd0f97a0901052154w213f9a03oafdd07645b1b7dc7@mail.gmail.com> <20090106061946.GA10026@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1911 Lines: 47 On Tue, Jan 6, 2009 at 01:19, Greg KH wrote: > On Tue, Jan 06, 2009 at 12:54:58AM -0500, Mike Frysinger wrote: >> On Tue, Jan 6, 2009 at 00:48, Greg KH wrote: >> > On Mon, Jan 05, 2009 at 09:57:07PM -0500, Robin Getz wrote: >> >> On 2.6.28-rc2, If I create a debugfs file with >> >> >> >> debugfs_create_x16("SPORT1_TX", 0200 , parent, 0xFFC00910); >> > >> > Um, are you are passing in a pointer to a known memory location >> > properly? Why would it be ok for the kernel to directly read that >> > location? >> >> it's a nommu system and the 0xffc00000+ addresses are always available > > Writable but not readable? Isn't hardware fun :) yeah and we have some readable but not writable addresses too :/ >> >> Although the file shows up as write only (no read): >> >> >> >> root:/> ls -l /sys/kernel/debug/blackfin/SPORT/SPORT1_TX >> >> --w------- 1 root root 0 Jan 1 >> >> 2007 /sys/kernel/debug/blackfin/SPORT/SPORT1_TX >> >> >> >> root:/> cat /sys/kernel/debug/blackfin/SPORT/SPORT1_TX >> >> >> >> Still works - and causes the read to occur, which crashes :( >> > >> > You're root, you can do anything :) >> >> any thoughts on how to declare debugfs files that are read or write >> only ? we'll have to add new helper functions or have it be a >> parameter or declare our own debugfs file ? > > Just use debugfs_create_file() and use your own read/write functions to > prevent a read or write from happening no matter what. No new debugfs > infrastructure should be needed. would it be useful for this to be a common function ? probably not so much considering (i'm assuming) no one else has asked so far for such a beast ... -mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/