2 * Copyright (c) 2017 Oliver Pinter
3 * Copyright (c) 2017 W. Dean Freeman
4 * Copyright (c) 2000-2015 Mark R V Murray
5 * Copyright (c) 2013 Arthur Mesh
6 * Copyright (c) 2004 Robert N. M. Watson
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer
14 * in this position and unchanged.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/systm.h>
38 #include <sys/eventhandler.h>
40 #include <sys/kernel.h>
41 #include <sys/kthread.h>
42 #include <sys/linker.h>
44 #include <sys/malloc.h>
45 #include <sys/module.h>
46 #include <sys/mutex.h>
47 #include <sys/random.h>
49 #include <sys/sysctl.h>
50 #include <sys/unistd.h>
52 #if defined(RANDOM_LOADABLE)
57 #include <machine/atomic.h>
58 #include <machine/cpu.h>
60 #include <dev/random/randomdev.h>
61 #include <dev/random/random_harvestq.h>
63 static void random_kthread(void);
64 static void random_sources_feed(void);
66 static u_int read_rate;
68 /* List for the dynamic sysctls */
69 static struct sysctl_ctx_list random_clist;
72 * How many events to queue up. We create this many items in
73 * an 'empty' queue, then transfer them to the 'harvest' queue with
74 * supplied junk. When used, they are transferred back to the
77 #define RANDOM_RING_MAX 1024
78 #define RANDOM_ACCUM_MAX 8
80 /* 1 to let the kernel thread run, 0 to terminate, -1 to mark completion */
81 volatile int random_kthread_control;
84 /* Allow the sysadmin to select the broad category of
85 * entropy types to harvest.
87 __read_frequently u_int hc_source_mask;
90 * Put all the harvest queue context stuff in one place.
91 * this make is a bit easier to lock and protect.
93 static struct harvest_context {
94 /* The harvest mutex protects all of harvest_context and
98 /* Round-robin destination cache. */
99 u_int hc_destination[ENTROPYSOURCE];
100 /* The context of the kernel thread processing harvested entropy */
101 struct proc *hc_kthread_proc;
103 * Lockless ring buffer holding entropy events
104 * If ring.in == ring.out,
105 * the buffer is empty.
106 * If ring.in != ring.out,
107 * the buffer contains harvested entropy.
108 * If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX),
109 * the buffer is full.
111 * NOTE: ring.in points to the last added element,
112 * and ring.out points to the last consumed element.
114 * The ring.in variable needs locking as there are multiple
115 * sources to the ring. Only the sources may change ring.in,
116 * but the consumer may examine it.
118 * The ring.out variable does not need locking as there is
119 * only one consumer. Only the consumer may change ring.out,
120 * but the sources may examine it.
122 struct entropy_ring {
123 struct harvest_event ring[RANDOM_RING_MAX];
127 struct fast_entropy_accumulator {
129 uint32_t buf[RANDOM_ACCUM_MAX];
130 } hc_entropy_fast_accumulator;
133 static struct kproc_desc random_proc_kp = {
136 &harvest_context.hc_kthread_proc,
139 /* Pass the given event straight through to Fortuna/Yarrow/Whatever. */
141 random_harvestq_fast_process_event(struct harvest_event *event)
143 #if defined(RANDOM_LOADABLE)
144 RANDOM_CONFIG_S_LOCK();
145 if (p_random_alg_context)
147 p_random_alg_context->ra_event_processor(event);
148 #if defined(RANDOM_LOADABLE)
149 RANDOM_CONFIG_S_UNLOCK();
156 u_int maxloop, ring_out, i;
159 * Locking is not needed as this is the only place we modify ring.out, and
160 * we only examine ring.in without changing it. Both of these are volatile,
161 * and this is a unique thread.
163 for (random_kthread_control = 1; random_kthread_control;) {
164 /* Deal with events, if any. Restrict the number we do in one go. */
165 maxloop = RANDOM_RING_MAX;
166 while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) {
167 ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX;
168 random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out);
169 harvest_context.hc_entropy_ring.out = ring_out;
173 random_sources_feed();
174 /* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */
175 for (i = 0; i < RANDOM_ACCUM_MAX; i++) {
176 if (harvest_context.hc_entropy_fast_accumulator.buf[i]) {
177 random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), 4, RANDOM_UMA);
178 harvest_context.hc_entropy_fast_accumulator.buf[i] = 0;
181 /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */
182 tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1));
184 random_kthread_control = -1;
185 wakeup(&harvest_context.hc_kthread_proc);
189 /* This happens well after SI_SUB_RANDOM */
190 SYSINIT(random_device_h_proc, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, kproc_start,
194 * Run through all fast sources reading entropy for the given
195 * number of rounds, which should be a multiple of the number
196 * of entropy accumulation pools in use; 2 for Yarrow and 32
200 random_sources_feed(void)
202 uint32_t entropy[HARVESTSIZE];
203 struct random_sources *rrs;
204 u_int i, n, local_read_rate;
207 * Step over all of live entropy sources, and feed their output
208 * to the system-wide RNG.
210 #if defined(RANDOM_LOADABLE)
211 RANDOM_CONFIG_S_LOCK();
212 if (p_random_alg_context) {
213 /* It's an indenting error. Yeah, Yeah. */
215 local_read_rate = atomic_readandclear_32(&read_rate);
216 LIST_FOREACH(rrs, &source_list, rrs_entries) {
217 for (i = 0; i < p_random_alg_context->ra_poolcount*(local_read_rate + 1); i++) {
218 n = rrs->rrs_source->rs_read(entropy, sizeof(entropy));
219 KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned too much data (%u > %zu)", __func__, n, sizeof(entropy)));
220 /* It would appear that in some circumstances (e.g. virtualisation),
221 * the underlying hardware entropy source might not always return
222 * random numbers. Accept this but make a noise. If too much happens,
223 * can that source be trusted?
226 printf("%s: rs_read for hardware device '%s' returned no entropy.\n", __func__, rrs->rrs_source->rs_ident);
229 random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source);
232 explicit_bzero(entropy, sizeof(entropy));
233 #if defined(RANDOM_LOADABLE)
235 RANDOM_CONFIG_S_UNLOCK();
240 read_rate_increment(u_int chunk)
243 atomic_add_32(&read_rate, chunk);
248 random_check_uint_harvestmask(SYSCTL_HANDLER_ARGS)
251 u_int value, orig_value;
253 orig_value = value = hc_source_mask;
254 error = sysctl_handle_int(oidp, &value, 0, req);
255 if (error != 0 || req->newptr == NULL)
258 if (flsl(value) > ENTROPYSOURCE)
262 * Disallow userspace modification of pure entropy sources.
264 hc_source_mask = (value & ~RANDOM_HARVEST_PURE_MASK) |
265 (orig_value & RANDOM_HARVEST_PURE_MASK);
271 random_print_harvestmask(SYSCTL_HANDLER_ARGS)
276 error = sysctl_wire_old_buffer(req, 0);
278 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
279 for (i = ENTROPYSOURCE - 1; i >= 0; i--)
280 sbuf_cat(&sbuf, (hc_source_mask & (1 << i)) ? "1" : "0");
281 error = sbuf_finish(&sbuf);
287 static const char *random_source_descr[ENTROPYSOURCE] = {
288 [RANDOM_CACHED] = "CACHED",
289 [RANDOM_ATTACH] = "ATTACH",
290 [RANDOM_KEYBOARD] = "KEYBOARD",
291 [RANDOM_MOUSE] = "MOUSE",
292 [RANDOM_NET_TUN] = "NET_TUN",
293 [RANDOM_NET_ETHER] = "NET_ETHER",
294 [RANDOM_NET_NG] = "NET_NG",
295 [RANDOM_INTERRUPT] = "INTERRUPT",
296 [RANDOM_SWI] = "SWI",
297 [RANDOM_FS_ATIME] = "FS_ATIME",
298 [RANDOM_UMA] = "UMA", /* ENVIRONMENTAL_END */
299 [RANDOM_PURE_OCTEON] = "PURE_OCTEON", /* PURE_START */
300 [RANDOM_PURE_SAFE] = "PURE_SAFE",
301 [RANDOM_PURE_GLXSB] = "PURE_GLXSB",
302 [RANDOM_PURE_UBSEC] = "PURE_UBSEC",
303 [RANDOM_PURE_HIFN] = "PURE_HIFN",
304 [RANDOM_PURE_RDRAND] = "PURE_RDRAND",
305 [RANDOM_PURE_NEHEMIAH] = "PURE_NEHEMIAH",
306 [RANDOM_PURE_RNDTEST] = "PURE_RNDTEST",
307 [RANDOM_PURE_VIRTIO] = "PURE_VIRTIO",
308 [RANDOM_PURE_BROADCOM] = "PURE_BROADCOM",
309 [RANDOM_PURE_CCP] = "PURE_CCP",
310 /* "ENTROPYSOURCE" */
315 random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS)
322 error = sysctl_wire_old_buffer(req, 0);
324 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
325 for (i = ENTROPYSOURCE - 1; i >= 0; i--) {
326 if (i >= RANDOM_PURE_START &&
327 (hc_source_mask & (1 << i)) == 0)
330 sbuf_cat(&sbuf, ",");
331 sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "[" : "");
332 sbuf_cat(&sbuf, random_source_descr[i]);
333 sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "]" : "");
336 error = sbuf_finish(&sbuf);
344 random_harvestq_init(void *unused __unused)
346 struct sysctl_oid *random_sys_o;
348 random_sys_o = SYSCTL_ADD_NODE(&random_clist,
349 SYSCTL_STATIC_CHILDREN(_kern_random),
350 OID_AUTO, "harvest", CTLFLAG_RW, 0,
351 "Entropy Device Parameters");
352 hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK;
353 SYSCTL_ADD_PROC(&random_clist,
354 SYSCTL_CHILDREN(random_sys_o),
355 OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW,
356 NULL, 0, random_check_uint_harvestmask, "IU",
357 "Entropy harvesting mask");
358 SYSCTL_ADD_PROC(&random_clist,
359 SYSCTL_CHILDREN(random_sys_o),
360 OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD,
361 NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)");
362 SYSCTL_ADD_PROC(&random_clist,
363 SYSCTL_CHILDREN(random_sys_o),
364 OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD,
365 NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)");
366 RANDOM_HARVEST_INIT_LOCK();
367 harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0;
369 SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL);
372 * This is used to prime the RNG by grabbing any early random stuff
373 * known to the kernel, and inserting it directly into the hashing
374 * module, e.g. Fortuna or Yarrow.
378 random_harvestq_prime(void *unused __unused)
380 struct harvest_event event;
381 size_t count, size, i;
382 uint8_t *keyfile, *data;
385 * Get entropy that may have been preloaded by loader(8)
386 * and use it to pre-charge the entropy harvest queue.
388 keyfile = preload_search_by_type(RANDOM_CACHED_BOOT_ENTROPY_MODULE);
389 #ifndef NO_BACKWARD_COMPATIBILITY
391 keyfile = preload_search_by_type(RANDOM_LEGACY_BOOT_ENTROPY_MODULE);
393 if (keyfile != NULL) {
394 data = preload_fetch_addr(keyfile);
395 size = preload_fetch_size(keyfile);
396 /* skip the first bit of the stash so others like arc4 can also have some. */
397 if (size > RANDOM_CACHED_SKIP_START) {
398 data += RANDOM_CACHED_SKIP_START;
399 size -= RANDOM_CACHED_SKIP_START;
401 /* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */
402 size -= (size % sizeof(event.he_entropy));
403 if (data != NULL && size != 0) {
404 for (i = 0; i < size; i += sizeof(event.he_entropy)) {
405 count = sizeof(event.he_entropy);
406 event.he_somecounter = (uint32_t)get_cyclecount();
407 event.he_size = count;
408 event.he_bits = count/4; /* Underestimate the size for Yarrow */
409 event.he_source = RANDOM_CACHED;
410 event.he_destination = harvest_context.hc_destination[0]++;
411 memcpy(event.he_entropy, data + i, sizeof(event.he_entropy));
412 random_harvestq_fast_process_event(&event);
413 explicit_bzero(&event, sizeof(event));
415 explicit_bzero(data, size);
417 printf("random: read %zu bytes from preloaded cache\n", size);
420 printf("random: no preloaded entropy cache\n");
423 SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, random_harvestq_prime, NULL);
427 random_harvestq_deinit(void *unused __unused)
430 /* Command the hash/reseed thread to end and wait for it to finish */
431 random_kthread_control = 0;
432 while (random_kthread_control >= 0)
433 tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", hz/5);
434 sysctl_ctx_free(&random_clist);
436 SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_deinit, NULL);
439 * Entropy harvesting queue routine.
441 * This is supposed to be fast; do not do anything slow in here!
442 * It is also illegal (and morally reprehensible) to insert any
443 * high-rate data here. "High-rate" is defined as a data source
444 * that will usually cause lots of failures of the "Lockless read"
445 * check a few lines below. This includes the "always-on" sources
446 * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources.
448 /* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle
449 * counters are built in, but on older hardware it will do a real time clock
450 * read which can be quite expensive.
453 random_harvest_queue_(const void *entropy, u_int size, u_int bits,
454 enum random_entropy_source origin)
456 struct harvest_event *event;
459 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
460 RANDOM_HARVEST_LOCK();
461 ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX;
462 if (ring_in != harvest_context.hc_entropy_ring.out) {
463 /* The ring is not full */
464 event = harvest_context.hc_entropy_ring.ring + ring_in;
465 event->he_somecounter = (uint32_t)get_cyclecount();
466 event->he_source = origin;
467 event->he_destination = harvest_context.hc_destination[origin]++;
468 event->he_bits = bits;
469 if (size <= sizeof(event->he_entropy)) {
470 event->he_size = size;
471 memcpy(event->he_entropy, entropy, size);
474 /* Big event, so squash it */
475 event->he_size = sizeof(event->he_entropy[0]);
476 event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event);
478 harvest_context.hc_entropy_ring.in = ring_in;
480 RANDOM_HARVEST_UNLOCK();
484 * Entropy harvesting fast routine.
486 * This is supposed to be very fast; do not do anything slow in here!
487 * This is the right place for high-rate harvested data.
490 random_harvest_fast_(const void *entropy, u_int size, u_int bits)
494 pos = harvest_context.hc_entropy_fast_accumulator.pos;
495 harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount());
496 harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX;
500 * Entropy harvesting direct routine.
502 * This is not supposed to be fast, but will only be used during
503 * (e.g.) booting when initial entropy is being gathered.
506 random_harvest_direct_(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin)
508 struct harvest_event event;
510 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
511 size = MIN(size, sizeof(event.he_entropy));
512 event.he_somecounter = (uint32_t)get_cyclecount();
513 event.he_size = size;
514 event.he_bits = bits;
515 event.he_source = origin;
516 event.he_destination = harvest_context.hc_destination[origin]++;
517 memcpy(event.he_entropy, entropy, size);
518 random_harvestq_fast_process_event(&event);
519 explicit_bzero(&event, sizeof(event));
523 random_harvest_register_source(enum random_entropy_source source)
526 hc_source_mask |= (1 << source);
530 random_harvest_deregister_source(enum random_entropy_source source)
533 hc_source_mask &= ~(1 << source);
536 MODULE_VERSION(random_harvestq, 1);