From b14959dacc796b287f2b8fc1da0bf975797ecf6f Mon Sep 17 00:00:00 2001 From: Justin Hibbits Date: Fri, 17 Aug 2018 03:49:07 +0000 Subject: [PATCH] random: Add PowerPC 'darn' instruction entropy source Summary: PowerISA 3.0 adds a 'darn' instruction to "deliver a random number". This driver was modeled after (rather, copied and gutted of) the Ivy Bridge rdrand driver. This uses the "Conditional Random Number" behavior to remove input bias. From the ISA reference the 'darn' instruction, and the random number generator backing it, conforms to the NIST SP800-90B and SP800-90C standards, compliant to the extent possible at the time the hardware was designed, and guarantees a minimum 0.5 bits of entropy per bit returned. Reviewed By: markm, secteam (delphij) Approved by: secteam (delphij) Differential Revision: https://reviews.freebsd.org/D16552 --- sys/conf/files.powerpc | 1 + sys/dev/random/darn.c | 142 +++++++++++++++++++++++++++++++ sys/dev/random/random_harvestq.c | 1 + sys/sys/random.h | 1 + 4 files changed, 145 insertions(+) create mode 100644 sys/dev/random/darn.c diff --git a/sys/conf/files.powerpc b/sys/conf/files.powerpc index 183796dc4cfc..d6df0c878641 100644 --- a/sys/conf/files.powerpc +++ b/sys/conf/files.powerpc @@ -63,6 +63,7 @@ dev/ofw/ofw_standard.c optional aim powerpc dev/ofw/ofw_subr.c standard dev/powermac_nvram/powermac_nvram.c optional powermac_nvram powermac dev/quicc/quicc_bfe_fdt.c optional quicc mpc85xx +dev/random/darn.c optional powerpc64 random dev/scc/scc_bfe_macio.c optional scc powermac dev/sdhci/fsl_sdhci.c optional mpc85xx sdhci dev/sec/sec.c optional sec mpc85xx diff --git a/sys/dev/random/darn.c b/sys/dev/random/darn.c new file mode 100644 index 000000000000..e42a4287a532 --- /dev/null +++ b/sys/dev/random/darn.c @@ -0,0 +1,142 @@ +/*- + * Copyright (c) 2018 Justin Hibbits + * Copyright (c) 2013 The FreeBSD Foundation + * Copyright (c) 2013 David E. O'Brien + * Copyright (c) 2012 Konstantin Belousov + * All rights reserved. + * + * Portions of this software were developed by Konstantin Belousov + * under sponsorship from the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer + * in this position and unchanged. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +#include +__FBSDID("$FreeBSD$"); + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include + +/* + * Power ISA 3.0 adds a "darn" instruction (Deliver A Random Number). The RNG + * backing this instruction conforms to NIST SP800-90B and SP800-90C at the + * point of hardware design, and provides a minimum of 0.5 bits of entropy per + * bit. + */ + +#define RETRY_COUNT 10 + +static u_int random_darn_read(void *, u_int); + +static struct random_source random_darn = { + .rs_ident = "PowerISA DARN random number generator", + .rs_source = RANDOM_PURE_DARN, + .rs_read = random_darn_read +}; + +static inline int +darn_rng_store(u_long *buf) +{ + u_long rndval; + int retry; + + for (retry = RETRY_COUNT; retry > 0; --retry) { + /* "DARN %rN, 1" instruction */ + /* + * Arguments for DARN: rN and "L", where "L" can be one of: + * 0 - 32-bit conditional random number + * 1 - Conditional random number (conditioned to remove bias) + * 2 - Raw random number (unprocessed, may include bias) + * 3 - Reserved + */ + __asm __volatile(".long 0x7c0105e6 | (%0 << 21)" : + "+r"(rndval)); + if (rndval != ~0) + break; + } + + *buf = rndval; + return (retry); +} + +/* It is required that buf length is a multiple of sizeof(u_long). */ +static u_int +random_darn_read(void *buf, u_int c) +{ + u_long *b, rndval; + u_int count; + + KASSERT(c % sizeof(*b) == 0, ("partial read %d", c)); + b = buf; + for (count = c; count > 0; count -= sizeof(*b)) { + if (darn_rng_store(&rndval) == 0) + break; + *b++ = rndval; + } + return (c - count); +} + +static int +darn_modevent(module_t mod, int type, void *unused) +{ + int error = 0; + + switch (type) { + case MOD_LOAD: + if (cpu_features2 & PPC_FEATURE2_DARN) { + random_source_register(&random_darn); + printf("random: fast provider: \"%s\"\n", random_darn.rs_ident); + } + break; + + case MOD_UNLOAD: + if (cpu_features2 & PPC_FEATURE2_DARN) + random_source_deregister(&random_darn); + break; + + case MOD_SHUTDOWN: + break; + + default: + error = EOPNOTSUPP; + break; + + } + + return (error); +} + +DEV_MODULE(darn, darn_modevent, NULL); +MODULE_VERSION(darn, 1); +MODULE_DEPEND(darn, random_device, 1, 1, 1); diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c index f064ab02b358..4f1494f96273 100644 --- a/sys/dev/random/random_harvestq.c +++ b/sys/dev/random/random_harvestq.c @@ -307,6 +307,7 @@ static const char *random_source_descr[ENTROPYSOURCE] = { [RANDOM_PURE_VIRTIO] = "PURE_VIRTIO", [RANDOM_PURE_BROADCOM] = "PURE_BROADCOM", [RANDOM_PURE_CCP] = "PURE_CCP", + [RANDOM_PURE_DARN] = "PURE_DARN", /* "ENTROPYSOURCE" */ }; diff --git a/sys/sys/random.h b/sys/sys/random.h index 74f3814ac5c5..59a3281c6641 100644 --- a/sys/sys/random.h +++ b/sys/sys/random.h @@ -95,6 +95,7 @@ enum random_entropy_source { RANDOM_PURE_VIRTIO, RANDOM_PURE_BROADCOM, RANDOM_PURE_CCP, + RANDOM_PURE_DARN, ENTROPYSOURCE };