2 * Copyright (c) 2000-2015 Mark R V Murray
3 * Copyright (c) 2013 Arthur Mesh
4 * Copyright (c) 2004 Robert N. M. Watson
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer
12 * in this position and unchanged.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #include <sys/param.h>
34 #include <sys/systm.h>
36 #include <sys/eventhandler.h>
38 #include <sys/kernel.h>
39 #include <sys/kthread.h>
40 #include <sys/linker.h>
42 #include <sys/malloc.h>
43 #include <sys/module.h>
44 #include <sys/mutex.h>
45 #include <sys/random.h>
47 #include <sys/sysctl.h>
48 #include <sys/unistd.h>
50 #if defined(RANDOM_LOADABLE)
55 #include <machine/atomic.h>
56 #include <machine/cpu.h>
58 #include <dev/random/randomdev.h>
59 #include <dev/random/random_harvestq.h>
61 static void random_kthread(void);
62 static void random_sources_feed(void);
64 static u_int read_rate;
66 /* List for the dynamic sysctls */
67 static struct sysctl_ctx_list random_clist;
70 * How many events to queue up. We create this many items in
71 * an 'empty' queue, then transfer them to the 'harvest' queue with
72 * supplied junk. When used, they are transferred back to the
75 #define RANDOM_RING_MAX 1024
76 #define RANDOM_ACCUM_MAX 8
78 /* 1 to let the kernel thread run, 0 to terminate, -1 to mark completion */
79 volatile int random_kthread_control;
82 * Put all the harvest queue context stuff in one place.
83 * this make is a bit easier to lock and protect.
85 static struct harvest_context {
86 /* The harvest mutex protects all of harvest_context and
90 /* Round-robin destination cache. */
91 u_int hc_destination[ENTROPYSOURCE];
92 /* The context of the kernel thread processing harvested entropy */
93 struct proc *hc_kthread_proc;
94 /* Allow the sysadmin to select the broad category of
95 * entropy types to harvest.
99 * Lockless ring buffer holding entropy events
100 * If ring.in == ring.out,
101 * the buffer is empty.
102 * If ring.in != ring.out,
103 * the buffer contains harvested entropy.
104 * If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX),
105 * the buffer is full.
107 * NOTE: ring.in points to the last added element,
108 * and ring.out points to the last consumed element.
110 * The ring.in variable needs locking as there are multiple
111 * sources to the ring. Only the sources may change ring.in,
112 * but the consumer may examine it.
114 * The ring.out variable does not need locking as there is
115 * only one consumer. Only the consumer may change ring.out,
116 * but the sources may examine it.
118 struct entropy_ring {
119 struct harvest_event ring[RANDOM_RING_MAX];
123 struct fast_entropy_accumulator {
125 uint32_t buf[RANDOM_ACCUM_MAX];
126 } hc_entropy_fast_accumulator;
129 static struct kproc_desc random_proc_kp = {
132 &harvest_context.hc_kthread_proc,
135 /* Pass the given event straight through to Fortuna/Yarrow/Whatever. */
137 random_harvestq_fast_process_event(struct harvest_event *event)
139 #if defined(RANDOM_LOADABLE)
140 RANDOM_CONFIG_S_LOCK();
141 if (p_random_alg_context)
143 p_random_alg_context->ra_event_processor(event);
144 #if defined(RANDOM_LOADABLE)
145 RANDOM_CONFIG_S_UNLOCK();
152 u_int maxloop, ring_out, i;
155 * Locking is not needed as this is the only place we modify ring.out, and
156 * we only examine ring.in without changing it. Both of these are volatile,
157 * and this is a unique thread.
159 for (random_kthread_control = 1; random_kthread_control;) {
160 /* Deal with events, if any. Restrict the number we do in one go. */
161 maxloop = RANDOM_RING_MAX;
162 while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) {
163 ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX;
164 random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out);
165 harvest_context.hc_entropy_ring.out = ring_out;
169 random_sources_feed();
170 /* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */
171 for (i = 0; i < RANDOM_ACCUM_MAX; i++) {
172 if (harvest_context.hc_entropy_fast_accumulator.buf[i]) {
173 random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), 4, RANDOM_UMA);
174 harvest_context.hc_entropy_fast_accumulator.buf[i] = 0;
177 /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */
178 tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1));
180 random_kthread_control = -1;
181 wakeup(&harvest_context.hc_kthread_proc);
185 /* This happens well after SI_SUB_RANDOM */
186 SYSINIT(random_device_h_proc, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, kproc_start,
190 * Run through all fast sources reading entropy for the given
191 * number of rounds, which should be a multiple of the number
192 * of entropy accumulation pools in use; 2 for Yarrow and 32
196 random_sources_feed(void)
198 uint32_t entropy[HARVESTSIZE];
199 struct random_sources *rrs;
200 u_int i, n, local_read_rate;
203 * Step over all of live entropy sources, and feed their output
204 * to the system-wide RNG.
206 #if defined(RANDOM_LOADABLE)
207 RANDOM_CONFIG_S_LOCK();
208 if (p_random_alg_context) {
209 /* It's an indenting error. Yeah, Yeah. */
211 local_read_rate = atomic_readandclear_32(&read_rate);
212 LIST_FOREACH(rrs, &source_list, rrs_entries) {
213 for (i = 0; i < p_random_alg_context->ra_poolcount*(local_read_rate + 1); i++) {
214 n = rrs->rrs_source->rs_read(entropy, sizeof(entropy));
215 KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned too much data (%u > %zu)", __func__, n, sizeof(entropy)));
216 /* It would appear that in some circumstances (e.g. virtualisation),
217 * the underlying hardware entropy source might not always return
218 * random numbers. Accept this but make a noise. If too much happens,
219 * can that source be trusted?
222 printf("%s: rs_read for hardware device '%s' returned no entropy.\n", __func__, rrs->rrs_source->rs_ident);
225 random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source);
228 explicit_bzero(entropy, sizeof(entropy));
229 #if defined(RANDOM_LOADABLE)
231 RANDOM_CONFIG_S_UNLOCK();
236 read_rate_increment(u_int chunk)
239 atomic_add_32(&read_rate, chunk);
243 RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_MASK);
247 random_print_harvestmask(SYSCTL_HANDLER_ARGS)
252 error = sysctl_wire_old_buffer(req, 0);
254 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
255 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--)
256 sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0");
257 error = sbuf_finish(&sbuf);
263 static const char *(random_source_descr[]) = {
274 "UMA", /* ENVIRONMENTAL_END */
283 /* "ENTROPYSOURCE" */
288 random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS)
293 error = sysctl_wire_old_buffer(req, 0);
295 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
296 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) {
297 sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ",");
298 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : "");
299 sbuf_cat(&sbuf, random_source_descr[i]);
300 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : "");
302 error = sbuf_finish(&sbuf);
310 random_harvestq_init(void *unused __unused)
312 struct sysctl_oid *random_sys_o;
314 random_sys_o = SYSCTL_ADD_NODE(&random_clist,
315 SYSCTL_STATIC_CHILDREN(_kern_random),
316 OID_AUTO, "harvest", CTLFLAG_RW, 0,
317 "Entropy Device Parameters");
318 harvest_context.hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK;
319 SYSCTL_ADD_PROC(&random_clist,
320 SYSCTL_CHILDREN(random_sys_o),
321 OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW,
322 &harvest_context.hc_source_mask, 0,
323 random_check_uint_harvestmask, "IU",
324 "Entropy harvesting mask");
325 SYSCTL_ADD_PROC(&random_clist,
326 SYSCTL_CHILDREN(random_sys_o),
327 OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD,
328 NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)");
329 SYSCTL_ADD_PROC(&random_clist,
330 SYSCTL_CHILDREN(random_sys_o),
331 OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD,
332 NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)");
333 RANDOM_HARVEST_INIT_LOCK();
334 harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0;
336 SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL);
339 * This is used to prime the RNG by grabbing any early random stuff
340 * known to the kernel, and inserting it directly into the hashing
341 * module, e.g. Fortuna or Yarrow.
345 random_harvestq_prime(void *unused __unused)
347 struct harvest_event event;
348 size_t count, size, i;
349 uint8_t *keyfile, *data;
352 * Get entropy that may have been preloaded by loader(8)
353 * and use it to pre-charge the entropy harvest queue.
355 keyfile = preload_search_by_type(RANDOM_CACHED_BOOT_ENTROPY_MODULE);
356 #ifndef NO_BACKWARD_COMPATIBILITY
358 keyfile = preload_search_by_type(RANDOM_LEGACY_BOOT_ENTROPY_MODULE);
360 if (keyfile != NULL) {
361 data = preload_fetch_addr(keyfile);
362 size = preload_fetch_size(keyfile);
363 /* skip the first bit of the stash so others like arc4 can also have some. */
364 if (size > RANDOM_CACHED_SKIP_START) {
365 data += RANDOM_CACHED_SKIP_START;
366 size -= RANDOM_CACHED_SKIP_START;
368 /* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */
369 size -= (size % sizeof(event.he_entropy));
370 if (data != NULL && size != 0) {
371 for (i = 0; i < size; i += sizeof(event.he_entropy)) {
372 count = sizeof(event.he_entropy);
373 event.he_somecounter = (uint32_t)get_cyclecount();
374 event.he_size = count;
375 event.he_bits = count/4; /* Underestimate the size for Yarrow */
376 event.he_source = RANDOM_CACHED;
377 event.he_destination = harvest_context.hc_destination[0]++;
378 memcpy(event.he_entropy, data + i, sizeof(event.he_entropy));
379 random_harvestq_fast_process_event(&event);
380 explicit_bzero(&event, sizeof(event));
382 explicit_bzero(data, size);
384 printf("random: read %zu bytes from preloaded cache\n", size);
387 printf("random: no preloaded entropy cache\n");
390 SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, random_harvestq_prime, NULL);
394 random_harvestq_deinit(void *unused __unused)
397 /* Command the hash/reseed thread to end and wait for it to finish */
398 random_kthread_control = 0;
399 while (random_kthread_control >= 0)
400 tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", hz/5);
401 sysctl_ctx_free(&random_clist);
403 SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_deinit, NULL);
406 * Entropy harvesting queue routine.
408 * This is supposed to be fast; do not do anything slow in here!
409 * It is also illegal (and morally reprehensible) to insert any
410 * high-rate data here. "High-rate" is defined as a data source
411 * that will usually cause lots of failures of the "Lockless read"
412 * check a few lines below. This includes the "always-on" sources
413 * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources.
415 /* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle
416 * counters are built in, but on older hardware it will do a real time clock
417 * read which can be quite expensive.
420 random_harvest_queue(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin)
422 struct harvest_event *event;
425 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
426 if (!(harvest_context.hc_source_mask & (1 << origin)))
428 RANDOM_HARVEST_LOCK();
429 ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX;
430 if (ring_in != harvest_context.hc_entropy_ring.out) {
431 /* The ring is not full */
432 event = harvest_context.hc_entropy_ring.ring + ring_in;
433 event->he_somecounter = (uint32_t)get_cyclecount();
434 event->he_source = origin;
435 event->he_destination = harvest_context.hc_destination[origin]++;
436 event->he_bits = bits;
437 if (size <= sizeof(event->he_entropy)) {
438 event->he_size = size;
439 memcpy(event->he_entropy, entropy, size);
442 /* Big event, so squash it */
443 event->he_size = sizeof(event->he_entropy[0]);
444 event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event);
446 harvest_context.hc_entropy_ring.in = ring_in;
448 RANDOM_HARVEST_UNLOCK();
452 * Entropy harvesting fast routine.
454 * This is supposed to be very fast; do not do anything slow in here!
455 * This is the right place for high-rate harvested data.
458 random_harvest_fast(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin)
462 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
463 /* XXX: FIX!! The above KASSERT is BS. Right now we ignore most structure and just accumulate the supplied data */
464 if (!(harvest_context.hc_source_mask & (1 << origin)))
466 pos = harvest_context.hc_entropy_fast_accumulator.pos;
467 harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount());
468 harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX;
472 * Entropy harvesting direct routine.
474 * This is not supposed to be fast, but will only be used during
475 * (e.g.) booting when initial entropy is being gathered.
478 random_harvest_direct(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin)
480 struct harvest_event event;
482 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
483 if (!(harvest_context.hc_source_mask & (1 << origin)))
485 size = MIN(size, sizeof(event.he_entropy));
486 event.he_somecounter = (uint32_t)get_cyclecount();
487 event.he_size = size;
488 event.he_bits = bits;
489 event.he_source = origin;
490 event.he_destination = harvest_context.hc_destination[origin]++;
491 memcpy(event.he_entropy, entropy, size);
492 random_harvestq_fast_process_event(&event);
493 explicit_bzero(&event, sizeof(event));
496 MODULE_VERSION(random_harvestq, 1);