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Date: Mon, 17 Mar 2014 17:50:12 +0100 From: Torsten Duwe <duwe@....de> To: "H. Peter Anvin" <hpa@...or.com>, Theodore Ts'o <tytso@....edu>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Matt Mackall <mpm@...enic.com>, Herbert Xu <herbert@...dor.apana.org.au>, Arnd Bergmann <arnd@...db.de>, Rusty Russell <rusty@...tcorp.com.au>, Satoru Takeuchi <satoru.takeuchi@...il.com> Cc: ingo.tuchscherer@...ibm.com, linux-kernel@...r.kernel.org, Hans-Georg Markgraf <MGRF@...ibm.com>, Gerald Schaefer <gerald.schaefer@...ibm.com>, Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, Joe Perches <joe@...ches.com> Subject: [Patch 01/03]: provide an injection point for pure hardware randomness This patch adds an interface to the random pool for feeding entropy in-kernel. It may serve as a destination for dedicated HWRNGs. It resembles -- and could be merged with -- the ioctl(RNDADDENTROPY) code, plus a sleep condition for eager writers. Signed-off-by: Torsten Duwe <duwe@...e.de> --- include/linux/hw_random.h | 2 ++ drivers/char/random.c | 23 +++++++++++++++++++++++ 2 files changed, 25 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, size_t entropy); #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> @@ -1347,3 +1347,25 @@ randomize_range(unsigned long start, uns 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() || + input_pool.entropy_count + <= random_write_wakeup_thresh); + mix_pool_bytes(poolp, buffer, count, NULL); + credit_entropy_bits(poolp, entropy); +} +EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); + -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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