linux-kernel - Re: [RFC PATCH v1 4/4] firmware loader: don't allow to request firmware via relative path

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Message-ID: <CACVXFVPMLqXr-9OFQqSBi9rKhN2475fw_LND1Tt+fx4cTrqBfA@mail.gmail.com>
Date:	Fri, 7 Jun 2013 22:54:47 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v1 4/4] firmware loader: don't allow to request
 firmware via relative path

On Fri, Jun 7, 2013 at 2:04 PM, Takashi Iwai <tiwai@...e.de> 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@...uxfoundation.org> 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.

Thanks
--
Ming Lei
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