diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2012-07-02 07:52:16 -0400 |
|---|---|---|
| committer | Paul Gortmaker <paul.gortmaker@windriver.com> | 2012-08-17 15:36:05 -0400 |
| commit | 17ef73f8c0be242d38efe9b28d9caaca9c3ef442 (patch) | |
| tree | 1a74e6fc35adb0a3ee19a21593eb5e2ce859d635 /kernel | |
| parent | a5c606bc8eef5c3153477f1eb0c6fbf54972e40a (diff) | |
random: make 'add_interrupt_randomness()' do something sane
commit 775f4b297b780601e61787b766f306ed3e1d23eb upstream.
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>
[PG: minor adjustment required since .34 doesn't have f9e4989eb8
which renames "status" to "random" in kernel/irq/handle.c ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/irq/handle.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index 76d5a671bfe1..86bcf104bdd5 100644 --- a/kernel/irq/handle.c +++ b/kernel/irq/handle.c @@ -368,7 +368,7 @@ static void warn_no_thread(unsigned int irq, struct irqaction *action) irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action) { irqreturn_t ret, retval = IRQ_NONE; - unsigned int status = 0; + unsigned int flags = 0; if (!(action->flags & IRQF_DISABLED)) local_irq_enable_in_hardirq(); @@ -411,7 +411,7 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action) /* Fall through to add to randomness */ case IRQ_HANDLED: - status |= action->flags; + flags |= action->flags; break; default: @@ -422,8 +422,7 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action) action = action->next; } while (action); - if (status & IRQF_SAMPLE_RANDOM) - add_interrupt_randomness(irq); + add_interrupt_randomness(irq, flags); local_irq_disable(); return retval; |