freebsd-skq/sys/dev/random/random_harvestq.c
jhb f8c8714465 Don't start the random harvester process until timers are working.
This is a no-op currently, but in kernels with earlier AP startup, the
random kthread was trying to use timeouts with sleeps before timers are
working.  Wait until SI_SUB_KICK_SCHEDULER to start the random kproc.

Reviewed by:	delphij, imp, markm
Approved by:	so
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D5712
2016-03-28 21:51:56 +00:00

488 lines
16 KiB
C

/*-
* 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/conf.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>
#if defined(RANDOM_LOADABLE)
#include <sys/lock.h>
#include <sys/sx.h>
#endif
#include <machine/atomic.h>
#include <machine/cpu.h>
#include <dev/random/randomdev.h>
#include <dev/random/random_harvestq.h>
static void random_kthread(void);
static void random_sources_feed(void);
static u_int read_rate;
/* List for the dynamic sysctls */
static struct sysctl_ctx_list random_clist;
/*
* 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;
/*
* 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;
/* Allow the sysadmin to select the broad category of
* entropy types to harvest.
*/
u_int hc_source_mask;
/*
* 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/Yarrow/Whatever. */
static __inline void
random_harvestq_fast_process_event(struct harvest_event *event)
{
#if defined(RANDOM_LOADABLE)
RANDOM_CONFIG_S_LOCK();
if (p_random_alg_context)
#endif
p_random_alg_context->ra_event_processor(event);
#if defined(RANDOM_LOADABLE)
RANDOM_CONFIG_S_UNLOCK();
#endif
}
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]), 4, 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);
/*
* 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; 2 for Yarrow and 32
* for Fortuna.
*/
static void
random_sources_feed(void)
{
uint32_t entropy[HARVESTSIZE];
struct random_sources *rrs;
u_int i, n, local_read_rate;
/*
* Step over all of live entropy sources, and feed their output
* to the system-wide RNG.
*/
#if defined(RANDOM_LOADABLE)
RANDOM_CONFIG_S_LOCK();
if (p_random_alg_context) {
/* It's an indenting error. Yeah, Yeah. */
#endif
local_read_rate = atomic_readandclear_32(&read_rate);
LIST_FOREACH(rrs, &source_list, rrs_entries) {
for (i = 0; i < p_random_alg_context->ra_poolcount*(local_read_rate + 1); 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)));
/* It would appear that in some circumstances (e.g. virtualisation),
* the underlying hardware entropy source might not always return
* random numbers. Accept this but make a noise. If too much happens,
* can that source be trusted?
*/
if (n == 0) {
printf("%s: rs_read for hardware device '%s' returned no entropy.\n", __func__, rrs->rrs_source->rs_ident);
continue;
}
random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source);
}
}
explicit_bzero(entropy, sizeof(entropy));
#if defined(RANDOM_LOADABLE)
}
RANDOM_CONFIG_S_UNLOCK();
#endif
}
void
read_rate_increment(u_int chunk)
{
atomic_add_32(&read_rate, chunk);
}
/* ARGSUSED */
RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_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 = RANDOM_ENVIRONMENTAL_END; i >= 0; i--)
sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0");
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
}
return (error);
}
static const char *(random_source_descr[]) = {
"CACHED",
"ATTACH",
"KEYBOARD",
"MOUSE",
"NET_TUN",
"NET_ETHER",
"NET_NG",
"INTERRUPT",
"SWI",
"FS_ATIME",
"UMA", /* ENVIRONMENTAL_END */
"PURE_OCTEON",
"PURE_SAFE",
"PURE_GLXSB",
"PURE_UBSEC",
"PURE_HIFN",
"PURE_RDRAND",
"PURE_NEHEMIAH",
"PURE_RNDTEST",
/* "ENTROPYSOURCE" */
};
/* ARGSUSED */
static int
random_print_harvestmask_symbolic(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 = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) {
sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ",");
sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : "");
sbuf_cat(&sbuf, random_source_descr[i]);
sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : "");
}
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
}
return (error);
}
/* ARGSUSED */
static void
random_harvestq_init(void *unused __unused)
{
struct sysctl_oid *random_sys_o;
random_sys_o = SYSCTL_ADD_NODE(&random_clist,
SYSCTL_STATIC_CHILDREN(_kern_random),
OID_AUTO, "harvest", CTLFLAG_RW, 0,
"Entropy Device Parameters");
harvest_context.hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK;
SYSCTL_ADD_PROC(&random_clist,
SYSCTL_CHILDREN(random_sys_o),
OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW,
&harvest_context.hc_source_mask, 0,
random_check_uint_harvestmask, "IU",
"Entropy harvesting mask");
SYSCTL_ADD_PROC(&random_clist,
SYSCTL_CHILDREN(random_sys_o),
OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD,
NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)");
SYSCTL_ADD_PROC(&random_clist,
SYSCTL_CHILDREN(random_sys_o),
OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD,
NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)");
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_SECOND, random_harvestq_init, NULL);
/*
* 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, e.g. Fortuna or Yarrow.
*/
/* ARGSUSED */
static void
random_harvestq_prime(void *unused __unused)
{
struct harvest_event event;
size_t count, size, i;
uint8_t *keyfile, *data;
/*
* Get entropy that may have been preloaded by loader(8)
* and use it to pre-charge the entropy harvest queue.
*/
keyfile = preload_search_by_type(RANDOM_HARVESTQ_BOOT_ENTROPY_FILE);
if (keyfile != NULL) {
data = preload_fetch_addr(keyfile);
size = preload_fetch_size(keyfile);
/* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */
size -= (size % sizeof(event.he_entropy));
if (data != NULL && size != 0) {
for (i = 0; i < size; i += sizeof(event.he_entropy)) {
count = sizeof(event.he_entropy);
event.he_somecounter = (uint32_t)get_cyclecount();
event.he_size = count;
event.he_bits = count/4; /* Underestimate the size for Yarrow */
event.he_source = RANDOM_CACHED;
event.he_destination = harvest_context.hc_destination[0]++;
memcpy(event.he_entropy, data + i, sizeof(event.he_entropy));
random_harvestq_fast_process_event(&event);
explicit_bzero(&event, sizeof(event));
}
explicit_bzero(data, size);
if (bootverbose)
printf("random: read %zu bytes from preloaded cache\n", size);
} else
if (bootverbose)
printf("random: no preloaded entropy cache\n");
}
}
SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, 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);
sysctl_ctx_free(&random_clist);
}
SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, 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, u_int bits, 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));
if (!(harvest_context.hc_source_mask & (1 << origin)))
return;
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]++;
event->he_bits = bits;
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 bits, enum random_entropy_source origin)
{
u_int pos;
KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
/* XXX: FIX!! The above KASSERT is BS. Right now we ignore most structure and just accumulate the supplied data */
if (!(harvest_context.hc_source_mask & (1 << origin)))
return;
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, u_int bits, enum random_entropy_source origin)
{
struct harvest_event event;
KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
if (!(harvest_context.hc_source_mask & (1 << origin)))
return;
size = MIN(size, sizeof(event.he_entropy));
event.he_somecounter = (uint32_t)get_cyclecount();
event.he_size = size;
event.he_bits = bits;
event.he_source = origin;
event.he_destination = harvest_context.hc_destination[origin]++;
memcpy(event.he_entropy, entropy, size);
random_harvestq_fast_process_event(&event);
explicit_bzero(&event, sizeof(event));
}
MODULE_VERSION(random_harvestq, 1);