Commit c84dbf61 authored by Torsten Duwe's avatar Torsten Duwe Committed by Theodore Ts'o
Browse files

random: add_hwgenerator_randomness() for feeding entropy from devices 



This patch adds an interface to the random pool for feeding entropy
in-kernel.

Signed-off-by: default avatarTorsten Duwe <duwe@suse.de>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 43759d4f

drivers/char/random.c

+21 −0
Original line number Diff line number Diff line
@@ -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>
@@ -1750,3 +1751,23 @@ randomize_range(unsigned long start, unsigned long end, unsigned long len) 
		return 0;

	return PAGE_ALIGN(get_random_int() % range + start);

}



/* 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,

				size_t entropy)

{

	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() ||

			ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);

	mix_pool_bytes(poolp, buffer, count);

	credit_entropy_bits(poolp, entropy);

}

EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);

include/linux/hw_random.h

+2 −0
Original line number Diff line number Diff line
@@ -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, size_t entropy);



#endif /* LINUX_HWRANDOM_H_ */