2 * Copyright (c) 2017 Oliver Pinter
3 * Copyright (c) 2000-2015 Mark R V Murray
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
36 #include <sys/fcntl.h>
37 #include <sys/filio.h>
38 #include <sys/kernel.h>
39 #include <sys/kthread.h>
41 #include <sys/module.h>
42 #include <sys/malloc.h>
45 #include <sys/random.h>
47 #include <sys/selinfo.h>
48 #include <sys/sysctl.h>
49 #include <sys/systm.h>
51 #include <sys/unistd.h>
53 #include <crypto/rijndael/rijndael-api-fst.h>
54 #include <crypto/sha2/sha256.h>
56 #include <dev/random/hash.h>
57 #include <dev/random/randomdev.h>
58 #include <dev/random/random_harvestq.h>
63 * In loadable random, the core randomdev.c / random(9) routines have static
64 * visibility and an alternative name to avoid conflicting with the function
65 * pointers of the real names in the core kernel. random_alg_context_init
66 * installs pointers to the loadable static names into the core kernel's
67 * function pointers at SI_SUB_RANDOM:SI_ORDER_SECOND.
69 #if defined(RANDOM_LOADABLE)
70 static int (read_random_uio)(struct uio *, bool);
71 static void (read_random)(void *, u_int);
72 static bool (is_random_seeded)(void);
75 static d_read_t randomdev_read;
76 static d_write_t randomdev_write;
77 static d_poll_t randomdev_poll;
78 static d_ioctl_t randomdev_ioctl;
80 static struct cdevsw random_cdevsw = {
82 .d_version = D_VERSION,
83 .d_read = randomdev_read,
84 .d_write = randomdev_write,
85 .d_poll = randomdev_poll,
86 .d_ioctl = randomdev_ioctl,
89 /* For use with make_dev(9)/destroy_dev(9). */
90 static struct cdev *random_dev;
92 #if defined(RANDOM_LOADABLE)
94 random_alg_context_init(void *dummy __unused)
96 _read_random_uio = (read_random_uio);
97 _read_random = (read_random);
98 _is_random_seeded = (is_random_seeded);
100 SYSINIT(random_device, SI_SUB_RANDOM, SI_ORDER_SECOND, random_alg_context_init,
104 static struct selinfo rsel;
107 * This is the read uio(9) interface for random(4).
111 randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags)
114 return ((read_random_uio)(uio, (flags & O_NONBLOCK) != 0));
118 * If the random device is not seeded, blocks until it is seeded.
120 * Returns zero when the random device is seeded.
122 * If the 'interruptible' parameter is true, and the device is unseeded, this
123 * routine may be interrupted. If interrupted, it will return either ERESTART
126 #define SEEDWAIT_INTERRUPTIBLE true
127 #define SEEDWAIT_UNINTERRUPTIBLE false
129 randomdev_wait_until_seeded(bool interruptible)
131 int error, spamcount, slpflags;
133 slpflags = interruptible ? PCATCH : 0;
137 while (!p_random_alg_context->ra_seeded()) {
138 /* keep tapping away at the pre-read until we seed/unblock. */
139 p_random_alg_context->ra_pre_read();
140 /* Only bother the console every 10 seconds or so */
142 printf("random: %s unblock wait\n", __func__);
143 spamcount = (spamcount + 1) % 100;
144 error = tsleep(p_random_alg_context, slpflags, "randseed",
146 if (error == ERESTART || error == EINTR) {
147 KASSERT(interruptible,
148 ("unexpected wake of non-interruptible sleep"));
151 /* Squash tsleep timeout condition */
152 if (error == EWOULDBLOCK)
154 KASSERT(error == 0, ("unexpected tsleep error %d", error));
160 (read_random_uio)(struct uio *uio, bool nonblock)
162 /* 16 MiB takes about 0.08 s CPU time on my 2017 AMD Zen CPU */
163 #define SIGCHK_PERIOD (16 * 1024 * 1024)
164 const size_t sigchk_period = SIGCHK_PERIOD;
165 CTASSERT(SIGCHK_PERIOD % PAGE_SIZE == 0);
169 size_t total_read, read_len;
174 KASSERT(uio->uio_rw == UIO_READ, ("%s: bogus write", __func__));
175 KASSERT(uio->uio_resid >= 0, ("%s: bogus negative resid", __func__));
177 p_random_alg_context->ra_pre_read();
179 /* (Un)Blocking logic */
180 if (!p_random_alg_context->ra_seeded()) {
184 error = randomdev_wait_until_seeded(
185 SEEDWAIT_INTERRUPTIBLE);
190 read_rate_increment(howmany(uio->uio_resid + 1, sizeof(uint32_t)));
193 /* Easy to deal with the trivial 0 byte case. */
194 if (__predict_false(uio->uio_resid == 0))
198 * If memory is plentiful, use maximally sized requests to avoid
199 * per-call algorithm overhead. But fall back to a single page
200 * allocation if the full request isn't immediately available.
202 bufsize = MIN(sigchk_period, (size_t)uio->uio_resid);
203 random_buf = malloc(bufsize, M_ENTROPY, M_NOWAIT);
204 if (random_buf == NULL) {
206 random_buf = malloc(bufsize, M_ENTROPY, M_WAITOK);
210 while (uio->uio_resid > 0 && error == 0) {
211 read_len = MIN((size_t)uio->uio_resid, bufsize);
213 p_random_alg_context->ra_read(random_buf, read_len);
216 * uiomove() may yield the CPU before each 'read_len' bytes (up
217 * to bufsize) are copied out.
219 error = uiomove(random_buf, read_len, uio);
220 total_read += read_len;
223 * Poll for signals every few MBs to avoid very long
224 * uninterruptible syscalls.
226 if (error == 0 && uio->uio_resid != 0 &&
227 total_read % sigchk_period == 0) {
228 error = tsleep_sbt(p_random_alg_context, PCATCH,
229 "randrd", SBT_1NS, 0, C_HARDCLOCK);
230 /* Squash tsleep timeout condition */
231 if (error == EWOULDBLOCK)
237 * Short reads due to signal interrupt should not indicate error.
238 * Instead, the uio will reflect that the read was shorter than
241 if (error == ERESTART || error == EINTR)
244 zfree(random_buf, M_ENTROPY);
249 * Kernel API version of read_random(). This is similar to read_random_uio(),
250 * except it doesn't interface with uio(9). It cannot assumed that random_buf
251 * is a multiple of RANDOM_BLOCKSIZE bytes.
253 * If the tunable 'kern.random.initial_seeding.bypass_before_seeding' is set
254 * non-zero, silently fail to emit random data (matching the pre-r346250
255 * behavior). If read_random is called prior to seeding and bypassed because
256 * of this tunable, the condition is reported in the read-only sysctl
257 * 'kern.random.initial_seeding.read_random_bypassed_before_seeding'.
260 (read_random)(void *random_buf, u_int len)
263 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__));
264 p_random_alg_context->ra_pre_read();
269 /* (Un)Blocking logic */
270 if (__predict_false(!p_random_alg_context->ra_seeded())) {
271 if (random_bypass_before_seeding) {
272 if (!read_random_bypassed_before_seeding) {
273 if (!random_bypass_disable_warnings)
274 printf("read_random: WARNING: bypassing"
275 " request for random data because "
276 "the random device is not yet "
277 "seeded and the knob "
278 "'bypass_before_seeding' was "
280 read_random_bypassed_before_seeding = true;
282 /* Avoid potentially leaking stack garbage */
283 memset(random_buf, 0, len);
287 (void)randomdev_wait_until_seeded(SEEDWAIT_UNINTERRUPTIBLE);
289 read_rate_increment(roundup2(len, sizeof(uint32_t)));
290 p_random_alg_context->ra_read(random_buf, len);
294 (is_random_seeded)(void)
296 return (p_random_alg_context->ra_seeded());
300 randomdev_accumulate(uint8_t *buf, u_int count)
302 static u_int destination = 0;
303 static struct harvest_event event;
304 static struct randomdev_hash hash;
305 static uint32_t entropy_data[RANDOM_KEYSIZE_WORDS];
309 /* Extra timing here is helpful to scrape scheduler jitter entropy */
310 randomdev_hash_init(&hash);
311 timestamp = (uint32_t)get_cyclecount();
312 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp));
313 randomdev_hash_iterate(&hash, buf, count);
314 timestamp = (uint32_t)get_cyclecount();
315 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp));
316 randomdev_hash_finish(&hash, entropy_data);
317 for (i = 0; i < RANDOM_KEYSIZE_WORDS; i += sizeof(event.he_entropy)/sizeof(event.he_entropy[0])) {
318 event.he_somecounter = (uint32_t)get_cyclecount();
319 event.he_size = sizeof(event.he_entropy);
320 event.he_source = RANDOM_CACHED;
321 event.he_destination = destination++; /* Harmless cheating */
322 memcpy(event.he_entropy, entropy_data + i, sizeof(event.he_entropy));
323 p_random_alg_context->ra_event_processor(&event);
325 explicit_bzero(&event, sizeof(event));
326 explicit_bzero(entropy_data, sizeof(entropy_data));
331 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
337 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
338 nbytes = uio->uio_resid;
339 while (uio->uio_resid > 0 && error == 0) {
340 c = MIN(uio->uio_resid, PAGE_SIZE);
341 error = uiomove(random_buf, c, uio);
344 randomdev_accumulate(random_buf, c);
345 tsleep(p_random_alg_context, 0, "randwr", hz/10);
347 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR))
348 /* Partial write, not error. */
350 free(random_buf, M_ENTROPY);
356 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused)
359 if (events & (POLLIN | POLLRDNORM)) {
360 if (p_random_alg_context->ra_seeded())
361 events &= (POLLIN | POLLRDNORM);
363 selrecord(td, &rsel);
368 /* This will be called by the entropy processor when it seeds itself and becomes secure */
370 randomdev_unblock(void)
373 selwakeuppri(&rsel, PUSER);
374 wakeup(p_random_alg_context);
375 printf("random: unblocking device.\n");
376 #ifndef RANDOM_FENESTRASX
377 /* Do random(9) a favour while we are about it. */
378 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE);
384 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
385 int flags __unused, struct thread *td __unused)
390 /* Really handled in upper layer */
403 randomdev_modevent(module_t mod __unused, int type, void *data __unused)
409 printf("random: entropy device external interface\n");
410 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
411 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random");
412 make_dev_alias(random_dev, "urandom"); /* compatibility */
426 static moduledata_t randomdev_mod = {
432 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
433 MODULE_VERSION(random_device, 1);
434 MODULE_DEPEND(random_device, crypto, 1, 1, 1);
435 MODULE_DEPEND(random_device, random_harvestq, 1, 1, 1);