Messages in this thread | | | Date | Fri, 15 Aug 2003 23:57:11 -0500 | From | Matt Mackall <> | Subject | Re: [RFC][PATCH] Make cryptoapi non-optional? |
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On Sat, Aug 16, 2003 at 01:58:07AM +0100, Jamie Lokier wrote: > Andrew Morton wrote: > > Matt Mackall <mpm@selenic.com> wrote: > > > I'm pretty sure there was never a time when entropy > > > accounting wasn't racy let alone wrong, SMP or no (fixed in -mm, thank > > > you). > > > > Well is has been argued that the lack of locking in the random driver is a > > "feature", adding a little more unpredictability. > > Dodgy. Does lack of locking mean users can trick /dev/random into > thinking it has more entropy than it does? Or let them detect the > time when /dev/random gains entropy, without reading it?
Yes to the first, detailed at great length in a separate message. You can do timing attacks on the inputs either way. I'll repost my fix for it eventually, it's low on the list.
> > Now I don't know if that makes sense or not, but the locking certainly has > > a cost. If it doesn't actually fix anything then that cost becomes a > > waste. > > Per-cpu random pools, perhaps :)
I really doubt contention here is significant, but will take about ten lines to address if these locks ever show up on someone's Specweb benchmark.
-- Matt Mackall : http://www.selenic.com : of or relating to the moon - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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