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/*-
* Copyright (c) 2013, 2025, David E. O'Brien <deo@NUXI.org>
* Copyright (c) 2013 The FreeBSD Foundation
* Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
* 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 <sys/param.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/random.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <machine/md_var.h>
#include <machine/specialreg.h>
#include <x86/ifunc.h>
#include <dev/random/randomdev.h>
#define RETRY_COUNT 10
static u_int random_rdseed_read(void *, u_int);
static struct random_source random_rdseed = {
.rs_ident = "Intel Secure Key Seed",
.rs_source = RANDOM_PURE_RDSEED,
.rs_read = random_rdseed_read
};
SYSCTL_NODE(_kern_random, OID_AUTO, rdseed, CTLFLAG_RW, 0,
"rdseed (x86) entropy source");
/* XXX: kern.random.rdseed.enabled=0 also disables RDRAND */
static bool enabled = true;
SYSCTL_BOOL(_kern_random_rdseed, OID_AUTO, enabled, CTLFLAG_RDTUN, &enabled, 0,
"If zero, disable the use of RDSEED.");
static bool
x86_rdseed_store(u_long *buf)
{
u_long rndval;
int retry;
retry = RETRY_COUNT;
__asm __volatile(
"1:\n\t"
"rdseed %1\n\t" /* read randomness into rndval */
"jc 2f\n\t" /* CF is set on success, exit retry loop */
"dec %0\n\t" /* otherwise, retry-- */
"jne 1b\n\t" /* and loop if retries are not exhausted */
"2:"
: "+r" (retry), "=r" (rndval) : : "cc");
*buf = rndval;
return (retry != 0);
}
/* It is required that buf length is a multiple of sizeof(u_long). */
static u_int
random_rdseed_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 (!x86_rdseed_store(&rndval))
break;
*b++ = rndval;
}
return (c - count);
}
static int
rdseed_modevent(module_t mod, int type, void *unused)
{
bool has_rdseed;
int error = 0;
has_rdseed = (cpu_stdext_feature & CPUID_STDEXT_RDSEED);
switch (type) {
case MOD_LOAD:
if (has_rdseed && enabled) {
random_source_register(&random_rdseed);
printf("random: fast provider: \"%s\"\n", random_rdseed.rs_ident);
}
break;
case MOD_UNLOAD:
if (has_rdseed)
random_source_deregister(&random_rdseed);
break;
case MOD_SHUTDOWN:
break;
default:
error = EOPNOTSUPP;
break;
}
return (error);
}
static moduledata_t rdseed_mod = {
"rdseed",
rdseed_modevent,
0
};
DECLARE_MODULE(rdseed, rdseed_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
MODULE_VERSION(rdseed, 1);
MODULE_DEPEND(rdseed, random_harvestq, 1, 1, 1);
/*
* Intel's RDSEED Entropy Assessment Report min-entropy claim is 0.6 Shannons
* per bit of data output. Rrefer to the following Entropy Source Validation
* (ESV) certificates:
*
* E#87: Junos OS Physical Entropy Source - Broadwell EP 10-Core Die
* Broadwell-EP-10 FCLGA2011 Intel(R) Xeon(R) E5-2620 V4 Processor
* https://csrc.nist.gov/projects/cryptographic-module-validation-program/entropy-validations/certificate/87
* (URLs below omitted for brevity but follow same format.)
*
* E#121: Junos OS Physical Entropy Source - Intel Atom C3000 Series
* (Denverton) 16 Core Die with FCBGA1310 Package
*
* E#122: Junos OS Physical Entropy Source - Intel Xeon D-1500 Family
* (Broadwell) 8 Core Die with FCBGA1667 Package
*
* E#123: Junos OS Physical Entropy Source - Intel Xeon D-2100 Series
* (Skylake) 18 Core Die with FCBGA2518 Package
*
* E#141: Junos OS Physical Entropy Source - Intel Xeon D-10 Series
* (Ice Lake-D-10) Die with FCBGA2227 Package
*
* E#169: Junos OS Physical Entropy Source - Intel Xeon AWS-1000 v4 and
* E5 v4 (Broadwell EP) 15 Core Die with FCLGA2011 Package
*/
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