/*-
* Copyright (c) 2017 Oliver Pinter
* Copyright (c) 2017 W. Dean Freeman
* Copyright (c) 2000-2015 Mark R V Murray
* Copyright (c) 2013 Arthur Mesh
* Copyright (c) 2004 Robert N. M. Watson
* All rights reserved.
*
* 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/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ck.h>
#include <sys/conf.h>
#include <sys/epoch.h>
#include <sys/eventhandler.h>
#include <sys/hash.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/random.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/unistd.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha256.h>
#include <dev/random/hash.h>
#include <dev/random/randomdev.h>
#include <dev/random/random_harvestq.h>
#if defined(RANDOM_ENABLE_ETHER)
#define _RANDOM_HARVEST_ETHER_OFF 0
#else
#define _RANDOM_HARVEST_ETHER_OFF (1u << RANDOM_NET_ETHER)
#endif
#if defined(RANDOM_ENABLE_UMA)
#define _RANDOM_HARVEST_UMA_OFF 0
#else
#define _RANDOM_HARVEST_UMA_OFF (1u << RANDOM_UMA)
#endif
static void random_kthread(void);
static void random_sources_feed(void);
static u_int read_rate;
/*
* Random must initialize much earlier than epoch, but we can initialize the
* epoch code before SMP starts. Prior to SMP, we can safely bypass
* concurrency primitives.
*/
static __read_mostly bool epoch_inited;
static __read_mostly epoch_t rs_epoch;
/*
* How many events to queue up. We create this many items in
* an 'empty' queue, then transfer them to the 'harvest' queue with
* supplied junk. When used, they are transferred back to the
* 'empty' queue.
*/
#define RANDOM_RING_MAX 1024
#define RANDOM_ACCUM_MAX 8
/* 1 to let the kernel thread run, 0 to terminate, -1 to mark completion */
volatile int random_kthread_control;
/* Allow the sysadmin to select the broad category of
* entropy types to harvest.
*/
__read_frequently u_int hc_source_mask;
struct random_sources {
CK_LIST_ENTRY(random_sources) rrs_entries;
struct random_source *rrs_source;
};
static CK_LIST_HEAD(sources_head, random_sources) source_list =
CK_LIST_HEAD_INITIALIZER(source_list);
SYSCTL_NODE(_kern_random, OID_AUTO, harvest, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"Entropy Device Parameters");
/*
* Put all the harvest queue context stuff in one place.
* this make is a bit easier to lock and protect.
*/
static struct harvest_context {
/* The harvest mutex protects all of harvest_context and
* the related data.
*/
struct mtx hc_mtx;
/* Round-robin destination cache. */
u_int hc_destination[ENTROPYSOURCE];
/* The context of the kernel thread processing harvested entropy */
struct proc *hc_kthread_proc;
/*
* Lockless ring buffer holding entropy events
* If ring.in == ring.out,
* the buffer is empty.
* If ring.in != ring.out,
* the buffer contains harvested entropy.
* If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX),
* the buffer is full.
*
* NOTE: ring.in points to the last added element,
* and ring.out points to the last consumed element.
*
* The ring.in variable needs locking as there are multiple
* sources to the ring. Only the sources may change ring.in,
* but the consumer may examine it.
*
* The ring.out variable does not need locking as there is
* only one consumer. Only the consumer may change ring.out,
* but the sources may examine it.
*/
struct entropy_ring {
struct harvest_event ring[RANDOM_RING_MAX];
volatile u_int in;
volatile u_int out;
} hc_entropy_ring;
struct fast_entropy_accumulator {
volatile u_int pos;
uint32_t buf[RANDOM_ACCUM_MAX];
} hc_entropy_fast_accumulator;
} harvest_context;
static struct kproc_desc random_proc_kp = {
"rand_harvestq",
random_kthread,
&harvest_context.hc_kthread_proc,
};
/* Pass the given event straight through to Fortuna/Whatever. */
static __inline void
random_harvestq_fast_process_event(struct harvest_event *event)
{
p_random_alg_context->ra_event_processor(event);
explicit_bzero(event, sizeof(*event));
}
static void
random_kthread(void)
{
u_int maxloop, ring_out, i;
/*
* Locking is not needed as this is the only place we modify ring.out, and
* we only examine ring.in without changing it. Both of these are volatile,
* and this is a unique thread.
*/
for (random_kthread_control = 1; random_kthread_control;) {
/* Deal with events, if any. Restrict the number we do in one go. */
maxloop = RANDOM_RING_MAX;
while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) {
ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX;
random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out);
harvest_context.hc_entropy_ring.out = ring_out;
if (!--maxloop)
break;
}
random_sources_feed();
/* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */
for (i = 0; i < RANDOM_ACCUM_MAX; i++) {
if (harvest_context.hc_entropy_fast_accumulator.buf[i]) {
random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), RANDOM_UMA);
harvest_context.hc_entropy_fast_accumulator.buf[i] = 0;
}
}
/* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */
tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1));
}
random_kthread_control = -1;
wakeup(&harvest_context.hc_kthread_proc);
kproc_exit(0);
/* NOTREACHED */
}
/* This happens well after SI_SUB_RANDOM */
SYSINIT(random_device_h_proc, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, kproc_start,
&random_proc_kp);
static void
rs_epoch_init(void *dummy __unused)
{
rs_epoch = epoch_alloc("Random Sources", EPOCH_PREEMPT);
epoch_inited = true;
}
SYSINIT(rs_epoch_init, SI_SUB_EPOCH, SI_ORDER_ANY, rs_epoch_init, NULL);
/*
* Run through all fast sources reading entropy for the given
* number of rounds, which should be a multiple of the number
* of entropy accumulation pools in use; it is 32 for Fortuna.
*/
static void
random_sources_feed(void)
{
uint32_t entropy[HARVESTSIZE];
struct epoch_tracker et;
struct random_sources *rrs;
u_int i, n, local_read_rate;
bool rse_warm;
rse_warm = epoch_inited;
/*
* Step over all of live entropy sources, and feed their output
* to the system-wide RNG.
*/
local_read_rate = atomic_readandclear_32(&read_rate);
/* Perform at least one read per round */
local_read_rate = MAX(local_read_rate, 1);
/* But not exceeding RANDOM_KEYSIZE_WORDS */
local_read_rate = MIN(local_read_rate, RANDOM_KEYSIZE_WORDS);
if (rse_warm)
epoch_enter_preempt(rs_epoch, &et);
CK_LIST_FOREACH(rrs, &source_list, rrs_entries) {
for (i = 0; i < p_random_alg_context->ra_poolcount*local_read_rate; i++) {
n = rrs->rrs_source->rs_read(entropy, sizeof(entropy));
KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned too much data (%u > %zu)", __func__, n, sizeof(entropy)));
/*
* Sometimes the HW entropy source doesn't have anything
* ready for us. This isn't necessarily untrustworthy.
* We don't perform any other verification of an entropy
* source (i.e., length is allowed to be anywhere from 1
* to sizeof(entropy), quality is unchecked, etc), so
* don't balk verbosely at slow random sources either.
* There are reports that RDSEED on x86 metal falls
* behind the rate at which we query it, for example.
* But it's still a better entropy source than RDRAND.
*/
if (n == 0)
continue;
random_harvest_direct(entropy, n, rrs->rrs_source->rs_source);
}
}
if (rse_warm)
epoch_exit_preempt(rs_epoch, &et);
explicit_bzero(entropy, sizeof(entropy));
}
void
read_rate_increment(u_int chunk)
{
atomic_add_32(&read_rate, chunk);
}
/* ARGSUSED */
static int
random_check_uint_harvestmask(SYSCTL_HANDLER_ARGS)
{
static const u_int user_immutable_mask =
(((1 << ENTROPYSOURCE) - 1) & (-1UL << RANDOM_PURE_START)) |
_RANDOM_HARVEST_ETHER_OFF | _RANDOM_HARVEST_UMA_OFF;
int error;
u_int value, orig_value;
orig_value = value = hc_source_mask;
error = sysctl_handle_int(oidp, &value, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (flsl(value) > ENTROPYSOURCE)
return (EINVAL);
/*
* Disallow userspace modification of pure entropy sources.
*/
hc_source_mask = (value & ~user_immutable_mask) |
(orig_value & user_immutable_mask);
return (0);
}
SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask,
CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
random_check_uint_harvestmask, "IU",
"Entropy harvesting mask");
/* ARGSUSED */
static int
random_print_harvestmask(SYSCTL_HANDLER_ARGS)
{
struct sbuf sbuf;
int error, i;
error = sysctl_wire_old_buffer(req, 0);
if (error == 0) {
sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
for (i = ENTROPYSOURCE - 1; i >= 0; i--)
sbuf_cat(&sbuf, (hc_source_mask & (1 << i)) ? "1" : "0");
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
}
return (error);
}
SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask_bin,
CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
random_print_harvestmask, "A",
"Entropy harvesting mask (printable)");
static const char *random_source_descr[ENTROPYSOURCE] = {
[RANDOM_CACHED] = "CACHED",
[RANDOM_ATTACH] = "ATTACH",
[RANDOM_KEYBOARD] = "KEYBOARD",
[RANDOM_MOUSE] = "MOUSE",
[RANDOM_NET_TUN] = "NET_TUN",
[RANDOM_NET_ETHER] = "NET_ETHER",
[RANDOM_NET_NG] = "NET_NG",
[RANDOM_INTERRUPT] = "INTERRUPT",
[RANDOM_SWI] = "SWI",
[RANDOM_FS_ATIME] = "FS_ATIME",
[RANDOM_UMA] = "UMA", /* ENVIRONMENTAL_END */
[RANDOM_PURE_OCTEON] = "PURE_OCTEON", /* PURE_START */
[RANDOM_PURE_SAFE] = "PURE_SAFE",
[RANDOM_PURE_GLXSB] = "PURE_GLXSB",
[RANDOM_PURE_HIFN] = "PURE_HIFN",
[RANDOM_PURE_RDRAND] = "PURE_RDRAND",
[RANDOM_PURE_NEHEMIAH] = "PURE_NEHEMIAH",
[RANDOM_PURE_RNDTEST] = "PURE_RNDTEST",
[RANDOM_PURE_VIRTIO] = "PURE_VIRTIO",
[RANDOM_PURE_BROADCOM] = "PURE_BROADCOM",
[RANDOM_PURE_CCP] = "PURE_CCP",
[RANDOM_PURE_DARN] = "PURE_DARN",
[RANDOM_PURE_TPM] = "PURE_TPM",
[RANDOM_PURE_VMGENID] = "VMGENID",
/* "ENTROPYSOURCE" */
};
/* ARGSUSED */
static int
random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS)
{
struct sbuf sbuf;
int error, i;
bool first;
first = true;
error = sysctl_wire_old_buffer(req, 0);
if (error == 0) {
sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
for (i = ENTROPYSOURCE - 1; i >= 0; i--) {
if (i >= RANDOM_PURE_START &&
(hc_source_mask & (1 << i)) == 0)
continue;
if (!first)
sbuf_cat(&sbuf, ",");
sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "[" : "");
sbuf_cat(&sbuf, random_source_descr[i]);
sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "]" : "");
first = false;
}
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
}
return (error);
}
SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask_symbolic,
CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
random_print_harvestmask_symbolic, "A",
"Entropy harvesting mask (symbolic)");
/* ARGSUSED */
static void
random_harvestq_init(void *unused __unused)
{
static const u_int almost_everything_mask =
(((1 << (RANDOM_ENVIRONMENTAL_END + 1)) - 1) &
~_RANDOM_HARVEST_ETHER_OFF & ~_RANDOM_HARVEST_UMA_OFF);
hc_source_mask = almost_everything_mask;
RANDOM_HARVEST_INIT_LOCK();
harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0;
}
SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_THIRD, random_harvestq_init, NULL);
/*
* Subroutine to slice up a contiguous chunk of 'entropy' and feed it into the
* underlying algorithm. Returns number of bytes actually fed into underlying
* algorithm.
*/
static size_t
random_early_prime(char *entropy, size_t len)
{
struct harvest_event event;
size_t i;
len = rounddown(len, sizeof(event.he_entropy));
if (len == 0)
return (0);
for (i = 0; i < len; i += sizeof(event.he_entropy)) {
event.he_somecounter = (uint32_t)get_cyclecount();
event.he_size = sizeof(event.he_entropy);
event.he_source = RANDOM_CACHED;
event.he_destination =
harvest_context.hc_destination[RANDOM_CACHED]++;
memcpy(event.he_entropy, entropy + i, sizeof(event.he_entropy));
random_harvestq_fast_process_event(&event);
}
explicit_bzero(entropy, len);
return (len);
}
/*
* Subroutine to search for known loader-loaded files in memory and feed them
* into the underlying algorithm early in boot. Returns the number of bytes
* loaded (zero if none were loaded).
*/
static size_t
random_prime_loader_file(const char *type)
{
uint8_t *keyfile, *data;
size_t size;
keyfile = preload_search_by_type(type);
if (keyfile == NULL)
return (0);
data = preload_fetch_addr(keyfile);
size = preload_fetch_size(keyfile);
if (data == NULL)
return (0);
return (random_early_prime(data, size));
}
/*
* This is used to prime the RNG by grabbing any early random stuff
* known to the kernel, and inserting it directly into the hashing
* module, currently Fortuna.
*/
/* ARGSUSED */
static void
random_harvestq_prime(void *unused __unused)
{
size_t size;
/*
* Get entropy that may have been preloaded by loader(8)
* and use it to pre-charge the entropy harvest queue.
*/
size = random_prime_loader_file(RANDOM_CACHED_BOOT_ENTROPY_MODULE);
if (bootverbose) {
if (size > 0)
printf("random: read %zu bytes from preloaded cache\n",
size);
else
printf("random: no preloaded entropy cache\n");
}
}
SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_MIDDLE, random_harvestq_prime, NULL);
/* ARGSUSED */
static void
random_harvestq_deinit(void *unused __unused)
{
/* Command the hash/reseed thread to end and wait for it to finish */
random_kthread_control = 0;
while (random_kthread_control >= 0)
tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", hz/5);
}
SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_THIRD, random_harvestq_deinit, NULL);
/*-
* Entropy harvesting queue routine.
*
* This is supposed to be fast; do not do anything slow in here!
* It is also illegal (and morally reprehensible) to insert any
* high-rate data here. "High-rate" is defined as a data source
* that will usually cause lots of failures of the "Lockless read"
* check a few lines below. This includes the "always-on" sources
* like the Intel "rdrand" or the VIA Nehamiah "xstore" sources.
*/
/* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle
* counters are built in, but on older hardware it will do a real time clock
* read which can be quite expensive.
*/
void
random_harvest_queue_(const void *entropy, u_int size, enum random_entropy_source origin)
{
struct harvest_event *event;
u_int ring_in;
KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
RANDOM_HARVEST_LOCK();
ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX;
if (ring_in != harvest_context.hc_entropy_ring.out) {
/* The ring is not full */
event = harvest_context.hc_entropy_ring.ring + ring_in;
event->he_somecounter = (uint32_t)get_cyclecount();
event->he_source = origin;
event->he_destination = harvest_context.hc_destination[origin]++;
if (size <= sizeof(event->he_entropy)) {
event->he_size = size;
memcpy(event->he_entropy, entropy, size);
}
else {
/* Big event, so squash it */
event->he_size = sizeof(event->he_entropy[0]);
event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event);
}
harvest_context.hc_entropy_ring.in = ring_in;
}
RANDOM_HARVEST_UNLOCK();
}
/*-
* Entropy harvesting fast routine.
*
* This is supposed to be very fast; do not do anything slow in here!
* This is the right place for high-rate harvested data.
*/
void
random_harvest_fast_(const void *entropy, u_int size)
{
u_int pos;
pos = harvest_context.hc_entropy_fast_accumulator.pos;
harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount());
harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX;
}
/*-
* Entropy harvesting direct routine.
*
* This is not supposed to be fast, but will only be used during
* (e.g.) booting when initial entropy is being gathered.
*/
void
random_harvest_direct_(const void *entropy, u_int size, enum random_entropy_source origin)
{
struct harvest_event event;
KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
size = MIN(size, sizeof(event.he_entropy));
event.he_somecounter = (uint32_t)get_cyclecount();
event.he_size = size;
event.he_source = origin;
event.he_destination = harvest_context.hc_destination[origin]++;
memcpy(event.he_entropy, entropy, size);
random_harvestq_fast_process_event(&event);
}
void
random_harvest_register_source(enum random_entropy_source source)
{
hc_source_mask |= (1 << source);
}
void
random_harvest_deregister_source(enum random_entropy_source source)
{
hc_source_mask &= ~(1 << source);
}
void
random_source_register(struct random_source *rsource)
{
struct random_sources *rrs;
KASSERT(rsource != NULL, ("invalid input to %s", __func__));
rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK);
rrs->rrs_source = rsource;
random_harvest_register_source(rsource->rs_source);
printf("random: registering fast source %s\n", rsource->rs_ident);
RANDOM_HARVEST_LOCK();
CK_LIST_INSERT_HEAD(&source_list, rrs, rrs_entries);
RANDOM_HARVEST_UNLOCK();
}
void
random_source_deregister(struct random_source *rsource)
{
struct random_sources *rrs = NULL;
KASSERT(rsource != NULL, ("invalid input to %s", __func__));
random_harvest_deregister_source(rsource->rs_source);
RANDOM_HARVEST_LOCK();
CK_LIST_FOREACH(rrs, &source_list, rrs_entries)
if (rrs->rrs_source == rsource) {
CK_LIST_REMOVE(rrs, rrs_entries);
break;
}
RANDOM_HARVEST_UNLOCK();
if (rrs != NULL && epoch_inited)
epoch_wait_preempt(rs_epoch);
free(rrs, M_ENTROPY);
}
static int
random_source_handler(SYSCTL_HANDLER_ARGS)
{
struct epoch_tracker et;
struct random_sources *rrs;
struct sbuf sbuf;
int error, count;
error = sysctl_wire_old_buffer(req, 0);
if (error != 0)
return (error);
sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
count = 0;
epoch_enter_preempt(rs_epoch, &et);
CK_LIST_FOREACH(rrs, &source_list, rrs_entries) {
sbuf_cat(&sbuf, (count++ ? ",'" : "'"));
sbuf_cat(&sbuf, rrs->rrs_source->rs_ident);
sbuf_cat(&sbuf, "'");
}
epoch_exit_preempt(rs_epoch, &et);
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
return (error);
}
SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
NULL, 0, random_source_handler, "A",
"List of active fast entropy sources.");
MODULE_VERSION(random_harvestq, 1);
