Re: [kernel-hardening] Re: [PATCH v4 13/13] random: warn when kernel uses unseeded randomness
From: Stephan Müller
Date: Sun Jun 18 2017 - 13:55:18 EST
Am Sonntag, 18. Juni 2017, 17:46:25 CEST schrieb Theodore Ts'o:
> > IMHO, users using the get_random_u64 or get_random_u32 are use cases that
> > do not require a fully seeded DRNG thus do not need a cryptographically
> > strong random number. Hence, I would think that the logging should be
> > removed from get_random_u32/u64.
> You are effectively proposing that there ought to be a middle range of
> security between prandom_32, get_random_u32/get_random_u64 and
> get_random_bytes(). I think that's going to lead to all sorts of
> complexity and bugs from people not understanding when they should use
> get_random_u32 vs get_random_bytes versus prandom_u32. And then we'll
> end up needing to audit all of the callsites for get_random_u32() so
> they don't violate this new usage rule that you are proposing.
I only proposed to get rid of the log messages indicating a non-seeded DRNG.
But you bring up an interesting point: if it is true you say that it is hard
for people to use differnent types of APIs regarding entropy and random
numbers right (which I would concur with), and considering that you imply that
get_random_bytes, get_random_u32 and get_random_u64 have the same security
strength, why do we have these three APIs to begin with? The get_random_bytes
API would then be more than enough.