Re: [RFC PATCH v1 4/4] firmware loader: don't allow to requestfirmware via relative path

From: Ming Lei
Date: Fri Jun 07 2013 - 10:54:54 EST

On Fri, Jun 7, 2013 at 2:04 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> At Fri, 7 Jun 2013 09:30:09 +0800,
> Ming Lei wrote:
>> On Fri, Jun 7, 2013 at 3:48 AM, Greg Kroah-Hartman
>> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>> > On Thu, Jun 06, 2013 at 08:01:50PM +0800, Ming Lei wrote:
>> >> It isn't a good pratice to request firmware via relative path, also
>> >> might have security issue, so don't do it.
>> >
>> > What would the security issue be? You are letting the person who build
>> > the kernel specify this, so they can put whatever they want in here, a
>> > '..' isn't going to keep them from being able to do "bad" things if they
>> > really want to.
>> In VM case, guest kernel might access host filesystem files via this trick,
>> but not sure if it is possible.
>> Takashi, could you explain the security issue of relative path?
> Well, I don't know, too. My original question was what happens if you
> pass a relative path to firmware_class.fw_path_para module option
> (or the new kconfig)...

OK, so please ignore the patch.

Ming Lei
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