Re: [PATCH 2/2 v2] tg3: Don't use IRQF_SAMPLE_RANDOM

[Ben Hutchings <bhutchings@solarflare.com>]

On Mon, 2011-03-28 at 17:46 +0200, Javier Martinez Canillas wrote:
> On Mon, Mar 28, 2011 at 2:25 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >
> > 1) We dont believe its Janitor material ;)
> >
> > http://thread.gmane.org/gmane.linux.kernel/680723
> >
> > http://kerneltrap.org/mailarchive/linux-netdev/2009/4/6/5417754
> >
> 
> I wasn't aware of this discussion. In one hand network drivers are not
> a good source of entropy because they can be controlled externally,
> but in embedded systems with only network cards (no video, audio,
> keyboard, etc) the only source of entropy they have is their network
> cards (at the kernel level i.e: not using EGD to feed /dev/random).

It may be the only source of entropy, but given how poor a source it is
these drivers are basically telling sweet little lies to the kernel and
the applications that demand real random numbers.

This also applies to many servers just as much as embedded systems.

As you acknowledge, these systems can still get entropy using the EGD
protocol over a secure channel.  (Or an entropy sampling device such as
the Entropy Key.)

> Yes this definitely is not janitor material :)
> 
> I just sent the patch because I saw IRQF_SAMPLE_RANDOM in
> Documentation/feature-removal-schedule.txt. I can resend a patch
> removing the macro in the remaining network cards if the decision is
> to remove IRQF_SAMPLE_RANDOM.

It's not my call, but I would support it.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.