netdev - RE: [PATCH] e1000e: write protect ICHx NVM to prevent malicious write/erase

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Date:	Thu, 2 Oct 2008 08:37:40 -0700
From:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
To:	"Jiri Kosina" <jkosina@...e.cz>
Cc:	<torvalds@...ux-foundation.org>, <jeff@...zik.org>,
	<davem@...emloft.net>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <arjan@...ux.intel.com>,
	"Allan, Bruce W" <bruce.w.allan@...el.com>, <arjan@...ux.intel.com>
Subject: RE: [PATCH] e1000e: write protect ICHx NVM to prevent malicious write/erase

Jiri Kosina wrote:
>> Set the hardware to ignore all write/erase cycles to the GbE region
>> in the ICHx NVM.  This feature can be disabled by the
>> WriteProtectNVM module parameter (enabled by default) only after a
>> hardware reset, but 
>> the machine must be power cycled before trying to enable writes.

> Does this impose any user-visible behavior change? (such as not being
> able to set up wake-on-lan, change MAC address, whatever).

no, because none of that is stored permanently in the eeprom unless you
do writes with ethtool -E.  Our policy for the driver is generally don't
ever write to the eeprom.  So all the normal paths (except for initial
start on preproduction hardware and ethtool -E writes) do not write to
the eeprom.

Currently the driver will let you try to commit a change but with this
patch it will never get written to NVM unless you reboot, load driver
(the first time!) with WriteProtectNVM=0 and *then* do ethtool -E.
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