]> git.proxmox.com Git - mirror_ubuntu-hirsute-kernel.git/commit - drivers/char/random.c
random: make 'add_interrupt_randomness()' do something sane
authorTheodore Ts'o <tytso@mit.edu>
Mon, 2 Jul 2012 11:52:16 +0000 (07:52 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Sun, 15 Jul 2012 00:17:28 +0000 (20:17 -0400)
commit775f4b297b780601e61787b766f306ed3e1d23eb
treee97e21669f0719636ccac0219f617bad6a0e8b54
parent74feec5dd83d879368c1081aec5b6a1cb6dd7ce2
random: make 'add_interrupt_randomness()' do something sane

We've been moving away from add_interrupt_randomness() for various
reasons: it's too expensive to do on every interrupt, and flooding the
CPU with interrupts could theoretically cause bogus floods of entropy
from a somewhat externally controllable source.

This solves both problems by limiting the actual randomness addition
to just once a second or after 64 interrupts, whicever comes first.
During that time, the interrupt cycle data is buffered up in a per-cpu
pool.  Also, we make sure the the nonblocking pool used by urandom is
initialized before we start feeding the normal input pool.  This
assures that /dev/urandom is returning unpredictable data as soon as
possible.

(Based on an original patch by Linus, but significantly modified by
tytso.)

Tested-by: Eric Wustrow <ewust@umich.edu>
Reported-by: Eric Wustrow <ewust@umich.edu>
Reported-by: Nadia Heninger <nadiah@cs.ucsd.edu>
Reported-by: Zakir Durumeric <zakir@umich.edu>
Reported-by: J. Alex Halderman <jhalderm@umich.edu>.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
drivers/char/random.c
drivers/mfd/ab3100-core.c
include/linux/random.h
kernel/irq/handle.c