Messages in this thread Patch in this message | | | Date | Thu, 12 Sep 2013 11:38:56 +0200 (CEST) | From | Torsten Duwe <> | Subject | [Resend PATCH 1/2] add direct interface for true hardware RNGs |
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This patch adds an interface to the random pool for feeding entropy in-kernel. It might be dangerous when some driver writers think they have "good" randomness when really they haven't.
Signed-off-by: Torsten Duwe <duwe@lst.de>
--- include/linux/hw_random.h | 2 ++ drivers/char/random.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+) --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -47,5 +47,7 @@ struct hwrng { extern int hwrng_register(struct hwrng *rng); /** Unregister a Hardware Random Number Generator driver. */ extern void hwrng_unregister(struct hwrng *rng); +/** Feed random bits into the pool. */ +extern void add_hwgenerator_randomness(const char *buffer, size_t count); #endif /* LINUX_HWRANDOM_H_ */ --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -250,6 +250,7 @@ #include <linux/interrupt.h> #include <linux/mm.h> #include <linux/spinlock.h> +#include <linux/kthread.h> #include <linux/percpu.h> #include <linux/cryptohash.h> #include <linux/fips.h> @@ -796,6 +797,25 @@ add_disk_randomness( } #endif +/* Interface for in-kernel drivers of true hardware RNGs. + * Those devices may produce endless random bits and will be throttled + * when our pool is full. + */ +void add_hwgenerator_randomness(const char *buffer, size_t count) +{ + struct entropy_store *poolp = &input_pool; + + /* Suspend writing if we're above the trickle threshold. + * We'll be woken up again once below random_write_wakeup_thresh, + * or when the calling thread is about to terminate. + */ + wait_event_interruptible(random_write_wait, kthread_should_stop() || + input_pool.entropy_count <= trickle_thresh); + mix_pool_bytes(poolp, buffer, count, NULL); + credit_entropy_bits(poolp, count*8); +} +EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); + /********************************************************************* * * Entropy extraction routines
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