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Koen Kooi
df83a59b6b
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net> Signed-off-by: Denys Dmytriyenko <denys@ti.com>
94 lines
3.6 KiB
Diff
94 lines
3.6 KiB
Diff
From 683cefe6594a919e89ca7d7d076ca753ced67679 Mon Sep 17 00:00:00 2001
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From: Linus Torvalds <torvalds@linux-foundation.org>
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Date: Wed, 4 Jul 2012 11:16:01 -0400
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Subject: [PATCH 16/70] random: create add_device_randomness() interface
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commit a2080a67abe9e314f9e9c2cc3a4a176e8a8f8793 upstream.
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Add a new interface, add_device_randomness() for adding data to the
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random pool that is likely to differ between two devices (or possibly
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even per boot). This would be things like MAC addresses or serial
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numbers, or the read-out of the RTC. This does *not* add any actual
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entropy to the pool, but it initializes the pool to different values
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for devices that might otherwise be identical and have very little
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entropy available to them (particularly common in the embedded world).
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[ Modified by tytso to mix in a timestamp, since there may be some
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variability caused by the time needed to detect/configure the hardware
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in question. ]
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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drivers/char/random.c | 28 ++++++++++++++++++++++++++++
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include/linux/random.h | 1 +
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2 files changed, 29 insertions(+), 0 deletions(-)
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diff --git a/drivers/char/random.c b/drivers/char/random.c
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index 8ac7e05..4446a27 100644
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--- a/drivers/char/random.c
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+++ b/drivers/char/random.c
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@@ -125,11 +125,20 @@
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* The current exported interfaces for gathering environmental noise
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* from the devices are:
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*
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+ * void add_device_randomness(const void *buf, unsigned int size);
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* void add_input_randomness(unsigned int type, unsigned int code,
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* unsigned int value);
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* void add_interrupt_randomness(int irq, int irq_flags);
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* void add_disk_randomness(struct gendisk *disk);
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*
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+ * add_device_randomness() is for adding data to the random pool that
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+ * is likely to differ between two devices (or possibly even per boot).
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+ * This would be things like MAC addresses or serial numbers, or the
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+ * read-out of the RTC. This does *not* add any actual entropy to the
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+ * pool, but it initializes the pool to different values for devices
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+ * that might otherwise be identical and have very little entropy
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+ * available to them (particularly common in the embedded world).
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+ *
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* add_input_randomness() uses the input layer interrupt timing, as well as
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* the event type information from the hardware.
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*
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@@ -646,6 +655,25 @@ static void set_timer_rand_state(unsigned int irq,
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}
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#endif
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+/*
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+ * Add device- or boot-specific data to the input and nonblocking
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+ * pools to help initialize them to unique values.
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+ *
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+ * None of this adds any entropy, it is meant to avoid the
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+ * problem of the nonblocking pool having similar initial state
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+ * across largely identical devices.
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+ */
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+void add_device_randomness(const void *buf, unsigned int size)
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+{
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+ unsigned long time = get_cycles() ^ jiffies;
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+
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+ mix_pool_bytes(&input_pool, buf, size, NULL);
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+ mix_pool_bytes(&input_pool, &time, sizeof(time), NULL);
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+ mix_pool_bytes(&nonblocking_pool, buf, size, NULL);
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+ mix_pool_bytes(&nonblocking_pool, &time, sizeof(time), NULL);
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+}
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+EXPORT_SYMBOL(add_device_randomness);
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+
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static struct timer_rand_state input_timer_state;
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/*
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diff --git a/include/linux/random.h b/include/linux/random.h
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index 6ef39d7..e14b438 100644
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--- a/include/linux/random.h
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+++ b/include/linux/random.h
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@@ -50,6 +50,7 @@ struct rnd_state {
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extern void rand_initialize_irq(int irq);
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+extern void add_device_randomness(const void *, unsigned int);
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extern void add_input_randomness(unsigned int type, unsigned int code,
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unsigned int value);
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extern void add_interrupt_randomness(int irq, int irq_flags);
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--
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1.7.7.6
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