linux-kernel - [PATCH v3 01/03]: hwrng: provide an injection point for pure hardware randomness

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140414160438.GA29351@lst.de>
Date:	Mon, 14 Apr 2014 18:04:38 +0200
From:	Torsten Duwe <duwe@....de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Theodore Ts'o <tytso@....edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.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>,
	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 v3 01/03]: hwrng: 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/