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[PATCH -v2 0/4] random: replace urandom pool with a CRNG

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  [PATCH -v2 0/4] random: replace urandom pool with a CRNG Theodore Ts'o <tytso@mit.edu> - 2016-05-04 21:30 +0200
    [PATCH 3/4] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o <tytso@mit.edu> - 2016-05-04 21:30 +0200

#1394663 — [PATCH -v2 0/4] random: replace urandom pool with a CRNG

By using a CRNG to replace the urandom pool, we address a number of
complaints which Stephan Mueller has been concerned about.  We now use
a much more aggressive interrupt sampling system to quickly initialize
a CRNG which gets used in place of the original non-blocking pool.
This tends to get initialized *very* quickly (before the devices are
finished being proved.)  Like Stephan's proposal, this assumes that we
can get a bit of entropy per interrupt, which may be problematic on
some architectures.  So after we do this quick-and-dirty
initialization, we then fall back to the slower, more conservative
interrupt sampling system to fill the input pool, and we will do a
catastrophic reseeding once we get 128 bits using the slower but more
conservative system, and every five minutes afterwards, if possible.

In addition, on NUMA systems we make the CRNG state per-NUMA socket,
to address the NUMA locking contention problem which Andi Kleen has
been complaining about.  I'm not entirely sure this will work on the
crazy big SGI systems, but they are rare.  Whether they are rarer than
abusive userspace programs that are continuously pounding /dev/urandom
is unclear.  If necessary we can make a config option to turn off the
per-NUMA socket hack if it proves to be problematic.

Stephan Mueller (1):
  random: add interrupt callback to VMBus IRQ handler

Theodore Ts'o (3):
  random: replace non-blocking pool with a Chacha20-based CRNG
  random: make /dev/urandom scalable for silly userspace programs
  random: add backtracking protection to the CRNG

 crypto/chacha20_generic.c |  61 --------
 drivers/char/random.c     | 372 +++++++++++++++++++++++++++++++++++++---------
 drivers/hv/vmbus_drv.c    |   3 +
 include/crypto/chacha20.h |   1 +
 lib/Makefile              |   2 +-
 lib/chacha20.c            |  79 ++++++++++
 6 files changed, 387 insertions(+), 131 deletions(-)
 create mode 100644 lib/chacha20.c

-- 
2.5.0

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#1394665 — [PATCH 3/4] random: add interrupt callback to VMBus IRQ handler

From: Stephan Mueller <smueller@chronox.de>

The Hyper-V Linux Integration Services use the VMBus implementation for
communication with the Hypervisor. VMBus registers its own interrupt
handler that completely bypasses the common Linux interrupt handling.
This implies that the interrupt entropy collector is not triggered.

This patch adds the interrupt entropy collection callback into the VMBus
interrupt handler function.

Signed-off-by: Stephan Mueller <stephan.mueller@atsec.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 drivers/char/random.c  | 1 +
 drivers/hv/vmbus_drv.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index b970db6..897c75e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1134,6 +1134,7 @@ void add_interrupt_randomness(int irq, int irq_flags)
 	/* award one bit for the contents of the fast pool */
 	credit_entropy_bits(r, credit + 1);
 }
+EXPORT_SYMBOL_GPL(add_interrupt_randomness);
 
 #ifdef CONFIG_BLOCK
 void add_disk_randomness(struct gendisk *disk)
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 64713ff..9af61bb 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -41,6 +41,7 @@
 #include <linux/ptrace.h>
 #include <linux/screen_info.h>
 #include <linux/kdebug.h>
+#include <linux/random.h>
 #include "hyperv_vmbus.h"
 
 static struct acpi_device  *hv_acpi_dev;
@@ -801,6 +802,8 @@ static void vmbus_isr(void)
 		else
 			tasklet_schedule(hv_context.msg_dpc[cpu]);
 	}
+
+	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
 }
 
 
-- 
2.5.0

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