From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756792AbaCQQuQ (ORCPT ); Mon, 17 Mar 2014 12:50:16 -0400 Received: from verein.lst.de ([213.95.11.211]:57440 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752777AbaCQQuO (ORCPT ); Mon, 17 Mar 2014 12:50:14 -0400 Date: Mon, 17 Mar 2014 17:50:12 +0100 From: Torsten Duwe To: "H. Peter Anvin" , "Theodore Ts'o" , Greg Kroah-Hartman , Matt Mackall , Herbert Xu , Arnd Bergmann , Rusty Russell , Satoru Takeuchi Cc: ingo.tuchscherer@de.ibm.com, linux-kernel@vger.kernel.org, Hans-Georg Markgraf , Gerald Schaefer , Martin Schwidefsky , Heiko Carstens , Joe Perches Subject: [Patch 01/03]: provide an injection point for pure hardware randomness Message-ID: <20140317165012.GC1763@lst.de> References: <52322621.3040908@zytor.com> <33dd164b-00a7-4cbd-9d62-66000ed4abbf@email.android.com> <20140317164842.GB1763@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140317164842.GB1763@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 #include #include +#include #include #include #include @@ -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); +