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Re: Guidance on conflicts between GNU GRUB and proprietary software


From: Brendan Trotter
Subject: Re: Guidance on conflicts between GNU GRUB and proprietary software
Date: Fri, 24 Sep 2010 20:27:49 +0930

Hi,

Just thought I'd throw my 2 cents in..

Any software (except the software that "owns" the MBR) that uses any
sectors that are in the first track with the MBR and outside of any
partition (e.g. before the first partition) is broken. Not only will
this broken software (potentially) conflict with the software that
"owns" the MBR (not just GRUB), but it will also (potentially)
conflict with any other pieces of broken software.

It does not matter if the broken software is proprietory of not, or if
broken software restrict users' freedom or not, or if broken software
is popular or well known or not, or if the broken software is
extremely useful and/or has an "excuse". All of these considerations
are irrelevant. The software touches something it shouldn't, therefore
it is broken.

I doubt that Windows is *directly* at fault. However, allowing broken
software access to these sectors is a security flaw. If Windows allows
software to tamper with these sectors, then what else does Windows
allow software to tamper with? Does Windows allow software to install
a virus in the MBR? Does Windows allow software to install a virus in
one or more sectors that are loaded (and executed) by the MBR? At a
minimum Windows should have a UAC warning (a dialog box requiring
admin privileges that alerts the user to the attempted access, and
gives them the option to deny permission), but I wouldn't be surprised
if there's none. If there is no such warning, then the issue should be
reported to Microsoft as a security vulnerability, because that's
exactly what it is.

While the situation is unfortunate, Vladimir's suggested use of
error-correcting code is a very good idea. However, I think it should
go one step further. If the user has several OSs, and each OS happens
to have several pieces of broken software that trash different
sectors, then simply avoiding those trashed sectors won't stop the
system from becoming unbootable. GRUB has to restore the rightful
contents of trashed sectors during boot to minimise the total number
of sectors that are trashed at any point in time. In addition to
increasing GRUB's ability to tolerate trashed sectors, this would also
help to discourage broken software (and possibly, make it easier for
users to identify which piece/s of software is broken).

As a service to end-users; it would also be very nice if GRUB
displayed a "high visibility" warning that something is tampering with
the system's security and attempted to identify which pieces of
software may be tampering with the system's security (so the user can
more easily identify the cause). This warning could/should include a
URL for a web page that explains the issue in more detail, and maybe a
hex dump from each trashed sector so that signatures can be obtained
more easily.

Also, as a service to end-users; if/when broken software is correctly
identified the publisher of that software should be informed of their
mistake - something like a formal email that (politely) explains to
them why their software is broken and (even more politely) requests
them to fix their broken software.


Cheers,

Brendan



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