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: <CACVXFVPtLHCNhuybkgUiHEYEcaB6BdCZs6M7QLHHsNdMfCtzug@mail.gmail.com>
Date:	Fri, 7 Jun 2013 09:30:09 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>
Subject: Re: [RFC PATCH v1 4/4] firmware loader: don't allow to request
 firmware via relative path

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?


Thanks,
--
Ming Lei
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