From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Landley Subject: Re: [PATCH v2 2/3] fpga manager: framework core Date: Mon, 08 Dec 2014 14:53:39 -0600 Message-ID: <54860FD3.6020502@landley.net> References: <1414007405-32186-1-git-send-email-atull@opensource.altera.com> <1414007405-32186-3-git-send-email-atull@opensource.altera.com> <20141024105200.GA20775@amd> <20141206135533.GA19672@amd> <20141208175050.92EDAC40D73@trevor.secretlab.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141208175050.92EDAC40D73@trevor.secretlab.ca> Sender: linux-doc-owner@vger.kernel.org To: Grant Likely , Pavel Machek Cc: atull , Pantelis Antoniou , Greg Kroah-Hartman , Jason Gunthorpe , "H. Peter Anvin" , Michal Simek , Michal Simek , Randy Dunlap , linux-kernel , "devicetree@vger.kernel.org" , Rob Herring , Ira Snyder , "linux-doc@vger.kernel.org" , Mark Brown , philip@balister.org, rubini , Steffen Trumtrar , Jason , kyle.teske@ni.com, Nicolas Pitre , Felipe Balbi , Mauro Carvalho Chehab , David Brown List-Id: devicetree@vger.kernel.org On 12/08/2014 11:50 AM, Grant Likely wrote: > On Sat, 6 Dec 2014 14:55:33 +0100 > , Pavel Machek > wrote: >> Hi! >> >>>> I am accustomed to doing 'echo -n' for most of sysfs anyway. Once in a >>>> while I am a bonehead and forget the '-n' and spend a few minutes >>>> wondering why this thing that worked last week suddenly rejects all >>>> commands. I'm just trying to make my user interface a bit user-friendly. >>>> >>>> I will take out the '\n' stripping and update the documentation. I didn't >>>> realize this would be controversial. >>> >>> Don't. You're doing the right thing by scrubbing your input. Requiring >>> 'echo -n' is just stupid when it is so easy to make work easily. >> >> 'foo\nbar\n' is unusual but valid filename in linux. It is bad idea to >> echo filenames into files in the first place... and arbitrarily >> disallowing certain filenames is not helping. > > Meh. Just because it is a valid linux filename doesn't mean this > interface is forced to accept it. There should be tighter rules about > how the filename can be constructed. Allowing any arbitrary path for any > arbitrary valid linux filename makes for a large attack surface. "echo /bin/mdev > /proc/sys/kernel/hotplug" has worked fine, without the -n, for most of a decade now. Requiring -n on echo would be weird. I note that the filenames in /proc/mounts have an escape syntax for arbitrary embedded weirdness. (To see it in action, mount a path with a space in it.) If you really want to support that, there's presumably code that can be genericized and reappropriated so you can escape a newline you want to keep. But if your input has a normal unescaped trailing newline, it _should_ be ignored. Rob