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Author Topic: How to protect plug from (unauthenticated) U-Boot access?  (Read 2514 times)
sdem
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« on: January 08, 2010, 04:32:17 PM »

Hello.

I'm a bit concerned that it's possible to use U-Boot to access the plug without any credentials, bypassing any security that is normally associated with Linux systems. I know that it is also true of "regular" systems, where you can boot off a floppy or so and change the root password (if you have physical access). But I was under the impression that such a compact system could be configured to behave 'atomically' -- so that tampering with it would result at best in a complete reset without access to prior data. This is required for an application where possibly sensitive data would be kept in a semi-publically accessible plug. Any idea on how to do that? Maybe through U-Boot options? Or by installing an alternate boot loader? Or do I have to cripple it physically (by removing the console hardware), and if so, how?
NB: I'm aware that I might not be able to reinstall the OS in case of loss of the password -- but it is OK.

Thanks!
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pingtoo
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« Reply #1 on: January 08, 2010, 04:39:55 PM »

Correct me if I am wrong, but my sense you are talking about production system. this Sheeva plug computer is a development kit. So it is made easy to access. You are correct to disable to console will give you what your described security but then you better off to ask Glbalscale to make something to your specification then to buy a development kit and try to alter it after market.

Just my two cents,  Grin
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dattaway
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« Reply #2 on: January 08, 2010, 08:51:34 PM »

Anyone with physical access to just about any device can use JTAG to install a new bootloader or manipulate the chips at will.
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sdem
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« Reply #3 on: January 09, 2010, 08:55:47 AM »

If thousands of units were to be deployed, then yes, making custom hardware would be the path. But we are talking about just a few ones. So the solution you prescribe is orders of magnitude more expensive than what I was thinking about.
Is there any way to disable access to the serial console and the JTAG altogether (by butchering the HW)?

Another way that I can think of dealing with this is to put the sensitive data in a TrueCrypt volume so it's not accessible anymore if restarted. But then the device needs to be powered at all times.
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pingtoo
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« Reply #4 on: January 09, 2010, 09:38:51 AM »

You can try pogoplug, it is more closed setup. a bit more expensive. a bit less memory.
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sdem
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« Reply #5 on: January 11, 2010, 09:44:48 AM »

Thanks. I've just looked at pogoplug. They don't provide much information on their site. But from pictures I've found on the net, it seems it is actually the same board as the sheevaplug -- so probably same security issue.
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pingtoo
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« Reply #6 on: January 11, 2010, 06:15:23 PM »

Then check the new ionics product, http://www.ionicsplug.com/compare.html. I think it is not shipping yet. but one of them should meet you need.
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sdem
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« Reply #7 on: January 21, 2010, 09:08:14 AM »

The Nimbus 200 is very lean indeed. Thanks for the pointer.
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MarkF
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« Reply #8 on: January 21, 2010, 11:59:11 AM »

Would changing the bootdelay environment variable to 0 be "good enough"?
Code:
setenv bootdelay 0
saveenv

I haven't tried this; but, in theory, it should make U-Boot not pause waiting for input. Smiley

EDIT: I just saw this thread where it says this version of U-Boot doesn't support this environment variable (yet).  My bad.  Sorry. Sad
« Last Edit: January 21, 2010, 12:02:49 PM by MarkF » Logged

Mark

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