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[PATCH v11 0/5] /dev/random - a new approach

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  [PATCH v11 0/5] /dev/random - a new approach Stephan Müller <smueller@chronox.de> - 2017-05-14 16:40 +0200
    [PATCH v11 2/5] random: conditionally compile code depending on LRNG Stephan Müller <smueller@chronox.de> - 2017-05-14 16:40 +0200
    [PATCH v11 1/5] crypto: DRBG - externalize DRBG functions for LRNG Stephan Müller <smueller@chronox.de> - 2017-05-14 16:40 +0200
    [PATCH v11 4/5] LRNG - enable compile Stephan Müller <smueller@chronox.de> - 2017-05-14 16:40 +0200

#1641096 — [PATCH v11 0/5] /dev/random - a new approach

Hi,

The following patch set provides a different approach to /dev/random which
I call Linux Random Number Generator (LRNG) to collect entropy within the Linux
kernel. The main improvements compared to the legacy /dev/random is to provide
sufficient entropy during boot time as well as in virtual environments and when
using SSDs. A secondary design goal is to limit the impact of the entropy
collection on massive parallel systems and also allow the use accelerated
cryptographic primitives. Also, all steps of the entropic data processing are
testable. Finally massive performance improvements are visible at /dev/urandom
and get_random_bytes.

The design and implementation is driven by a set of goals described in [1]
that the LRNG completely implements. Furthermore, [1] includes a
comparison with RNG design suggestions such as SP800-90B, SP800-90C, and
AIS20/31.

The LRNG has a flexible design by allowing an easy replacement of the
deterministic random number generator component. Currently implemented DRNGs
are an SP800-90A DRBG and a ChaCha20 DRNG.

[1] http://www.chronox.de/lrng.html

Changes v11 (compared to v9):
* port to 4.12-rc1
* contintionally compile JitterRNG code depending on CONFIG_CRYPTO_JITTERENTROPY
* update error code path when lrng_hash_buffer fails to report the successfully
  read entropy
* remove LRNG_DRBG_BLOCKLEN_BYTES in favor of LRNG_DRBG_BLOCKSIZE
* add get_random_u64 and get_random_u32 from legacy /dev/random to prevent
  any modifications of random.c
* move LRNG to drivers/char/
* wakeup user space writers only when entropy in pool is low (not when primary
  DRBG entropy is low)
* LFSR alteration to space the processed words 67 words apart to counter
  polynomial taps that are close together which may be affected by dependencies
* Always mix in an interrupt time stamp even when considered stuck, just do not
  increment number of collected interrupts used to determine the entropy content

Stephan Mueller (5):
  crypto: DRBG - externalize DRBG functions for LRNG
  random: conditionally compile code depending on LRNG
  Linux Random Number Generator
  LRNG - enable compile
  LRNG - add ChaCha20 support

 crypto/drbg.c                  |   11 +-
 drivers/char/Kconfig           |    9 +
 drivers/char/Makefile          |   15 +-
 drivers/char/lrng_base.c       | 2283 ++++++++++++++++++++++++++++++++++++++++
 drivers/char/lrng_kcapi.c      |  173 +++
 drivers/char/lrng_standalone.c |  325 ++++++
 include/crypto/drbg.h          |    7 +
 include/linux/genhd.h          |    5 +
 8 files changed, 2821 insertions(+), 7 deletions(-)
 create mode 100644 drivers/char/lrng_base.c
 create mode 100644 drivers/char/lrng_kcapi.c
 create mode 100644 drivers/char/lrng_standalone.c

-- 
2.9.3

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#1641097 — [PATCH v11 2/5] random: conditionally compile code depending on LRNG

When selecting the LRNG for compilation, disable the legacy /dev/random
implementation.

The LRNG is a drop-in replacement for the legacy /dev/random which
implements the same in-kernel and user space API. Only the hooks of
/dev/random into other parts of the kernel need to be disabled.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 include/linux/genhd.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index acff943..2a8d748 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -428,8 +428,13 @@ extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
 extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);
 
 /* drivers/char/random.c */
+#ifdef CONFIG_LRNG
+#define add_disk_randomness(disk) do {} while (0)
+#define rand_initialize_disk(disk) do {} while (0)
+#else
 extern void add_disk_randomness(struct gendisk *disk) __latent_entropy;
 extern void rand_initialize_disk(struct gendisk *disk);
+#endif
 
 static inline sector_t get_start_sect(struct block_device *bdev)
 {
-- 
2.9.3

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#1641099 — [PATCH v11 1/5] crypto: DRBG - externalize DRBG functions for LRNG

This patch allows several DRBG functions to be called by the LRNG kernel
code paths outside the drbg.c file.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/drbg.c         | 11 +++++------
 include/crypto/drbg.h |  7 +++++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index fa749f4..2ab8721 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -113,7 +113,7 @@
  * the SHA256 / AES 256 over other ciphers. Thus, the favored
  * DRBGs are the latest entries in this array.
  */
-static const struct drbg_core drbg_cores[] = {
+const struct drbg_core drbg_cores[] = {
 #ifdef CONFIG_CRYPTO_DRBG_CTR
 	{
 		.flags = DRBG_CTR | DRBG_STRENGTH128,
@@ -205,7 +205,7 @@ static int drbg_uninstantiate(struct drbg_state *drbg);
  * Return: normalized strength in *bytes* value or 32 as default
  *	   to counter programming errors
  */
-static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
+unsigned short drbg_sec_strength(drbg_flag_t flags)
 {
 	switch (flags & DRBG_STRENGTH_MASK) {
 	case DRBG_STRENGTH128:
@@ -1129,7 +1129,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 }
 
 /* Free all substructures in a DRBG state without the DRBG state structure */
-static inline void drbg_dealloc_state(struct drbg_state *drbg)
+void drbg_dealloc_state(struct drbg_state *drbg)
 {
 	if (!drbg)
 		return;
@@ -1148,7 +1148,7 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg)
  * Allocate all sub-structures for a DRBG state.
  * The DRBG state structure must already be allocated.
  */
-static inline int drbg_alloc_state(struct drbg_state *drbg)
+int drbg_alloc_state(struct drbg_state *drbg)
 {
 	int ret = -ENOMEM;
 	unsigned int sb_size = 0;
@@ -1806,8 +1806,7 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
  *
  * return: flags
  */
-static inline void drbg_convert_tfm_core(const char *cra_driver_name,
-					 int *coreref, bool *pr)
+void drbg_convert_tfm_core(const char *cra_driver_name, int *coreref, bool *pr)
 {
 	int i = 0;
 	size_t start = 0;
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index 22f884c..eaedeb78 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -282,4 +282,11 @@ enum drbg_prefixes {
 	DRBG_PREFIX3
 };
 
+extern int drbg_alloc_state(struct drbg_state *drbg);
+extern void drbg_dealloc_state(struct drbg_state *drbg);
+extern void drbg_convert_tfm_core(const char *cra_driver_name, int *coreref,
+				  bool *pr);
+extern const struct drbg_core drbg_cores[];
+extern unsigned short drbg_sec_strength(drbg_flag_t flags);
+
 #endif /* _DRBG_H */
-- 
2.9.3

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#1641100 — [PATCH v11 4/5] LRNG - enable compile

Add LRNG compilation support.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 drivers/char/Kconfig  | 10 ++++++++++
 drivers/char/Makefile | 10 +++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 31adbeb..ee26190 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -594,5 +594,15 @@ config TILE_SROM
 
 source "drivers/char/xillybus/Kconfig"
 
+config LRNG
+	bool "Linux Random Number Generator"
+	select CRYPTO_DRBG_MENU
+	select CRYPTO_CMAC if CRYPTO_DRBG_CTR
+	help
+	  The Linux Random Number Generator (LRNG) is the replacement
+	  of the legacy /dev/random provided with drivers/char/random.c.
+	  It generates entropy from different noise sources and
+	  delivers significant entropy during boot.
+
 endmenu
 
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 6e6c244..618bebb 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -2,7 +2,15 @@
 # Makefile for the kernel character device drivers.
 #
 
-obj-y				+= mem.o random.o
+obj-y				+= mem.o
+
+ifeq ($(CONFIG_LRNG),y)
+  obj-$(CONFIG_LRNG)		+= lrng.o
+  lrng-y			+= lrng_base.o lrng_kcapi.o
+else
+  obj-y				+= random.o
+endif
+
 obj-$(CONFIG_TTY_PRINTK)	+= ttyprintk.o
 obj-y				+= misc.o
 obj-$(CONFIG_ATARI_DSP56K)	+= dsp56k.o
-- 
2.9.3

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