Ted Ts'o wrote:
On Wed, Sep 07, 2011 at 02:26:35PM -0400, Jarod Wilson wrote:
We're looking for a generic solution here that doesn't require
re-educating every single piece of userspace. And anything done in
userspace is going to be full of possible holes -- there needs to be
something in place that actually *enforces* the policy, and
centralized accounting/tracking, lest you wind up with multiple
processes racing to grab the entropy.
Yeah, but there are userspace programs that depend on urandom not
blocking... so your proposed change would break them.
But only if you've set the sysctl to a non-zero value, and even then,
only if someone is actively draining entropy from /dev/random.
Otherwise, in practice, it behaves the same as always. Granted, I
haven't tested with all possible userspace to see how it might fall
down, but suggestions for progs to try would be welcomed.
But again, I want to stress that out of the box, there's absolutely no
change to the way urandom behaves, no blocking, this *only* kicks in if
you twiddle the sysctl because you have some sort of security
requirement that mandates it.
--
Jarod Wilson
jarod@xxxxxxxxxx
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