1 /*-
2 * Copyright (c) 2000-2015 Mark R V Murray
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer
10 * in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/bus.h>
34 #include <sys/conf.h>
35 #include <sys/fcntl.h>
36 #include <sys/filio.h>
37 #include <sys/kernel.h>
38 #include <sys/kthread.h>
39 #include <sys/lock.h>
40 #include <sys/module.h>
41 #include <sys/malloc.h>
42 #include <sys/poll.h>
43 #include <sys/proc.h>
44 #include <sys/random.h>
45 #include <sys/sbuf.h>
46 #include <sys/selinfo.h>
47 #include <sys/sysctl.h>
48 #include <sys/systm.h>
49 #include <sys/uio.h>
50 #include <sys/unistd.h>
51
52 #include <crypto/rijndael/rijndael-api-fst.h>
53 #include <crypto/sha2/sha256.h>
54
55 #include <dev/random/hash.h>
56 #include <dev/random/randomdev.h>
57 #include <dev/random/random_harvestq.h>
58
59 #define RANDOM_UNIT 0
60
61 #if defined(RANDOM_LOADABLE)
62 #define READ_RANDOM_UIO _read_random_uio
63 #define READ_RANDOM _read_random
64 static int READ_RANDOM_UIO(struct uio *, bool);
65 static u_int READ_RANDOM(void *, u_int);
66 #else
67 #define READ_RANDOM_UIO read_random_uio
68 #define READ_RANDOM read_random
69 #endif
70
71 static d_read_t randomdev_read;
72 static d_write_t randomdev_write;
73 static d_poll_t randomdev_poll;
74 static d_ioctl_t randomdev_ioctl;
75
76 static struct cdevsw random_cdevsw = {
77 .d_name = "random",
78 .d_version = D_VERSION,
79 .d_read = randomdev_read,
80 .d_write = randomdev_write,
81 .d_poll = randomdev_poll,
82 .d_ioctl = randomdev_ioctl,
83 };
84
85 /* For use with make_dev(9)/destroy_dev(9). */
86 static struct cdev *random_dev;
87
88 static void
random_alg_context_ra_init_alg(void * data)89 random_alg_context_ra_init_alg(void *data)
90 {
91
92 p_random_alg_context = &random_alg_context;
93 p_random_alg_context->ra_init_alg(data);
94 #if defined(RANDOM_LOADABLE)
95 random_infra_init(READ_RANDOM_UIO, READ_RANDOM);
96 #endif
97 }
98
99 static void
random_alg_context_ra_deinit_alg(void * data)100 random_alg_context_ra_deinit_alg(void *data)
101 {
102
103 #if defined(RANDOM_LOADABLE)
104 random_infra_uninit();
105 #endif
106 p_random_alg_context->ra_deinit_alg(data);
107 p_random_alg_context = NULL;
108 }
109
110 SYSINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_init_alg, NULL);
111 SYSUNINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_deinit_alg, NULL);
112
113 static struct selinfo rsel;
114
115 /*
116 * This is the read uio(9) interface for random(4).
117 */
118 /* ARGSUSED */
119 static int
randomdev_read(struct cdev * dev __unused,struct uio * uio,int flags)120 randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags)
121 {
122
123 return (READ_RANDOM_UIO(uio, (flags & O_NONBLOCK) != 0));
124 }
125
126 int
READ_RANDOM_UIO(struct uio * uio,bool nonblock)127 READ_RANDOM_UIO(struct uio *uio, bool nonblock)
128 {
129 uint8_t *random_buf;
130 int error, spamcount;
131 ssize_t read_len, total_read, c;
132
133 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
134 p_random_alg_context->ra_pre_read();
135 error = 0;
136 spamcount = 0;
137 /* (Un)Blocking logic */
138 while (!p_random_alg_context->ra_seeded()) {
139 if (nonblock) {
140 error = EWOULDBLOCK;
141 break;
142 }
143 /* keep tapping away at the pre-read until we seed/unblock. */
144 p_random_alg_context->ra_pre_read();
145 /* Only bother the console every 10 seconds or so */
146 if (spamcount == 0)
147 printf("random: %s unblock wait\n", __func__);
148 spamcount = (spamcount + 1)%100;
149 error = tsleep(&random_alg_context, PCATCH, "randseed", hz/10);
150 if (error == ERESTART || error == EINTR)
151 break;
152 /* Squash tsleep timeout condition */
153 if (error == EWOULDBLOCK)
154 error = 0;
155 KASSERT(error == 0, ("unexpected tsleep error %d", error));
156 }
157 if (error == 0) {
158 read_rate_increment((uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t));
159 total_read = 0;
160 while (uio->uio_resid && !error) {
161 read_len = uio->uio_resid;
162 /*
163 * Belt-and-braces.
164 * Round up the read length to a crypto block size multiple,
165 * which is what the underlying generator is expecting.
166 * See the random_buf size requirements in the Yarrow/Fortuna code.
167 */
168 read_len = roundup(read_len, RANDOM_BLOCKSIZE);
169 /* Work in chunks page-sized or less */
170 read_len = MIN(read_len, PAGE_SIZE);
171 p_random_alg_context->ra_read(random_buf, read_len);
172 c = MIN(uio->uio_resid, read_len);
173 error = uiomove(random_buf, c, uio);
174 total_read += c;
175 }
176 if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR))
177 /* Return partial read, not error. */
178 error = 0;
179 }
180 free(random_buf, M_ENTROPY);
181 return (error);
182 }
183
184 /*-
185 * Kernel API version of read_random().
186 * This is similar to random_alg_read(),
187 * except it doesn't interface with uio(9).
188 * It cannot assumed that random_buf is a multiple of
189 * RANDOM_BLOCKSIZE bytes.
190 */
191 u_int
READ_RANDOM(void * random_buf,u_int len)192 READ_RANDOM(void *random_buf, u_int len)
193 {
194 u_int read_len;
195 uint8_t local_buf[len + RANDOM_BLOCKSIZE];
196
197 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__));
198 p_random_alg_context->ra_pre_read();
199 /* (Un)Blocking logic; if not seeded, return nothing. */
200 if (p_random_alg_context->ra_seeded()) {
201 read_rate_increment((len + sizeof(uint32_t))/sizeof(uint32_t));
202 if (len > 0) {
203 /*
204 * Belt-and-braces.
205 * Round up the read length to a crypto block size multiple,
206 * which is what the underlying generator is expecting.
207 */
208 read_len = roundup(len, RANDOM_BLOCKSIZE);
209 p_random_alg_context->ra_read(local_buf, read_len);
210 memcpy(random_buf, local_buf, len);
211 }
212 } else
213 len = 0;
214 return (len);
215 }
216
217 static __inline void
randomdev_accumulate(uint8_t * buf,u_int count)218 randomdev_accumulate(uint8_t *buf, u_int count)
219 {
220 static u_int destination = 0;
221 static struct harvest_event event;
222 static struct randomdev_hash hash;
223 static uint32_t entropy_data[RANDOM_KEYSIZE_WORDS];
224 uint32_t timestamp;
225 int i;
226
227 /* Extra timing here is helpful to scrape scheduler jitter entropy */
228 randomdev_hash_init(&hash);
229 timestamp = (uint32_t)get_cyclecount();
230 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp));
231 randomdev_hash_iterate(&hash, buf, count);
232 timestamp = (uint32_t)get_cyclecount();
233 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp));
234 randomdev_hash_finish(&hash, entropy_data);
235 explicit_bzero(&hash, sizeof(hash));
236 for (i = 0; i < RANDOM_KEYSIZE_WORDS; i += sizeof(event.he_entropy)/sizeof(event.he_entropy[0])) {
237 event.he_somecounter = (uint32_t)get_cyclecount();
238 event.he_size = sizeof(event.he_entropy);
239 event.he_bits = event.he_size/8;
240 event.he_source = RANDOM_CACHED;
241 event.he_destination = destination++; /* Harmless cheating */
242 memcpy(event.he_entropy, entropy_data + i, sizeof(event.he_entropy));
243 p_random_alg_context->ra_event_processor(&event);
244 }
245 explicit_bzero(entropy_data, sizeof(entropy_data));
246 }
247
248 /* ARGSUSED */
249 static int
randomdev_write(struct cdev * dev __unused,struct uio * uio,int flags __unused)250 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
251 {
252 uint8_t *random_buf;
253 int c, error = 0;
254 ssize_t nbytes;
255
256 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
257 nbytes = uio->uio_resid;
258 while (uio->uio_resid > 0 && error == 0) {
259 c = MIN(uio->uio_resid, PAGE_SIZE);
260 error = uiomove(random_buf, c, uio);
261 if (error)
262 break;
263 randomdev_accumulate(random_buf, c);
264 tsleep(&random_alg_context, 0, "randwr", hz/10);
265 }
266 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR))
267 /* Partial write, not error. */
268 error = 0;
269 free(random_buf, M_ENTROPY);
270 return (error);
271 }
272
273 /* ARGSUSED */
274 static int
randomdev_poll(struct cdev * dev __unused,int events,struct thread * td __unused)275 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused)
276 {
277
278 if (events & (POLLIN | POLLRDNORM)) {
279 if (p_random_alg_context->ra_seeded())
280 events &= (POLLIN | POLLRDNORM);
281 else
282 selrecord(td, &rsel);
283 }
284 return (events);
285 }
286
287 /* This will be called by the entropy processor when it seeds itself and becomes secure */
288 void
randomdev_unblock(void)289 randomdev_unblock(void)
290 {
291
292 selwakeuppri(&rsel, PUSER);
293 wakeup(&random_alg_context);
294 printf("random: unblocking device.\n");
295 /* Do random(9) a favour while we are about it. */
296 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE);
297 }
298
299 /* ARGSUSED */
300 static int
randomdev_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t addr __unused,int flags __unused,struct thread * td __unused)301 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
302 int flags __unused, struct thread *td __unused)
303 {
304 int error = 0;
305
306 switch (cmd) {
307 /* Really handled in upper layer */
308 case FIOASYNC:
309 case FIONBIO:
310 break;
311 default:
312 error = ENOTTY;
313 }
314
315 return (error);
316 }
317
318 void
random_source_register(struct random_source * rsource)319 random_source_register(struct random_source *rsource)
320 {
321 struct random_sources *rrs;
322
323 KASSERT(rsource != NULL, ("invalid input to %s", __func__));
324
325 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK);
326 rrs->rrs_source = rsource;
327
328 printf("random: registering fast source %s\n", rsource->rs_ident);
329 LIST_INSERT_HEAD(&source_list, rrs, rrs_entries);
330 }
331
332 void
random_source_deregister(struct random_source * rsource)333 random_source_deregister(struct random_source *rsource)
334 {
335 struct random_sources *rrs = NULL;
336
337 KASSERT(rsource != NULL, ("invalid input to %s", __func__));
338 LIST_FOREACH(rrs, &source_list, rrs_entries)
339 if (rrs->rrs_source == rsource) {
340 LIST_REMOVE(rrs, rrs_entries);
341 break;
342 }
343 if (rrs != NULL)
344 free(rrs, M_ENTROPY);
345 }
346
347 static int
random_source_handler(SYSCTL_HANDLER_ARGS)348 random_source_handler(SYSCTL_HANDLER_ARGS)
349 {
350 struct random_sources *rrs;
351 struct sbuf sbuf;
352 int error, count;
353
354 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
355 count = 0;
356 LIST_FOREACH(rrs, &source_list, rrs_entries) {
357 sbuf_cat(&sbuf, (count++ ? ",'" : "'"));
358 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident);
359 sbuf_cat(&sbuf, "'");
360 }
361 error = sbuf_finish(&sbuf);
362 sbuf_delete(&sbuf);
363 return (error);
364 }
365 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
366 NULL, 0, random_source_handler, "A",
367 "List of active fast entropy sources.");
368
369 /* ARGSUSED */
370 static int
randomdev_modevent(module_t mod __unused,int type,void * data __unused)371 randomdev_modevent(module_t mod __unused, int type, void *data __unused)
372 {
373 int error = 0;
374
375 switch (type) {
376 case MOD_LOAD:
377 printf("random: entropy device external interface\n");
378 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
379 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random");
380 make_dev_alias(random_dev, "urandom"); /* compatibility */
381 break;
382 case MOD_UNLOAD:
383 destroy_dev(random_dev);
384 break;
385 case MOD_SHUTDOWN:
386 break;
387 default:
388 error = EOPNOTSUPP;
389 break;
390 }
391 return (error);
392 }
393
394 static moduledata_t randomdev_mod = {
395 "random_device",
396 randomdev_modevent,
397 0
398 };
399
400 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
401 MODULE_VERSION(random_device, 1);
402 MODULE_DEPEND(random_device, crypto, 1, 1, 1);
403 MODULE_DEPEND(random_device, random_harvestq, 1, 1, 1);
404