[OLPC Security] OFW system copier key -- security review for immediate signing

Mitch Bradley wmb at laptop.org
Fri Sep 5 04:54:47 EDT 2008

The attached "saver.fth" is an improved version of the earlier script.  
This one has an expiration date built in.  If the system time is bad, or 
if it is after Sept 12, the script won't run (it will display a message 
and suspend, powering off when you bring it out of suspend).

The expiration date is on line 35; if the one-week expiration is too 
short or too long, please change it.

I do not wish to participate in discussions of how long the interval 
should be.

I have tested the script on a system with q2e15, with today's date and 
with the system clock artificially set to a date after the expiration.  
It works correctly in both cases.  There are also a few error checks for 
firmware that is so down-rev that a few key security functions are 
missing.  If those checks fail, the script tells you to update the 
firmware.  I don't know how old the UY firmware is.

Erik Garrison wrote:
> Techteam and Security,
> Attached is a 32-line OFW Forth script which, when run from OFW on a XO,
> saves the NAND FLASH of the XO to a file on the usb flash drive from
> which it is run, then shuts down the machine.  For convenience the
> filename corresponds to the equipment's serial number.  Users are
> notified if an error occurs during the process.
> The script is necessary because it allows the acquisition of such images
> in cases where the laptop is locked, unbootable, or it is otherwise
> inconvenient or impossible to acquire a developer key so that the NAND
> FLASH can be copied from OFW.  It will allow us to speed the acquisition
> of system images from the field and improve available feedback about the
> usage of our systems in the wild.
> I wrote the script with the guidance of Mitch Bradley, and have tested
> it from the OFW prompt of an unlocked machine.
> Please approve and sign this image ASAP so that it can be used to copy
> the disk images of unsecured laptops here in Uruguay.  There is some
> time sensitivitiy to this issue, as I only have one more day at LATU to
> acquire NAND images to start testing our upgrade systems.
> Erik

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