1 /*- 2 * Copyright (c) 2000, 2001, 2002, 2003 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/malloc.h> 41 #include <sys/mutex.h> 42 #include <sys/poll.h> 43 #include <sys/proc.h> 44 #include <sys/random.h> 45 #include <sys/selinfo.h> 46 #include <sys/sysctl.h> 47 #include <sys/uio.h> 48 #include <sys/unistd.h> 49 #include <sys/vnode.h> 50 51 #include <machine/bus.h> 52 #include <machine/cpu.h> 53 54 #include <dev/random/randomdev.h> 55 56 static d_close_t random_close; 57 static d_read_t random_read; 58 static d_write_t random_write; 59 static d_ioctl_t random_ioctl; 60 static d_poll_t random_poll; 61 62 #define RANDOM_MINOR 0 63 64 #define RANDOM_FIFO_MAX 256 /* How many events to queue up */ 65 66 static struct cdevsw random_cdevsw = { 67 .d_close = random_close, 68 .d_read = random_read, 69 .d_write = random_write, 70 .d_ioctl = random_ioctl, 71 .d_poll = random_poll, 72 .d_name = "random", 73 }; 74 75 static void random_kthread(void *); 76 static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource); 77 static void random_write_internal(void *, int); 78 79 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers"); 80 81 /* Lockable FIFO queue holding entropy buffers */ 82 struct entropyfifo { 83 struct mtx lock; 84 int count; 85 STAILQ_HEAD(harvestlist, harvest) head; 86 }; 87 88 /* Empty entropy buffers */ 89 static struct entropyfifo emptyfifo; 90 #define EMPTYBUFFERS 1024 91 92 /* Harvested entropy */ 93 static struct entropyfifo harvestfifo[ENTROPYSOURCE]; 94 95 static struct random_systat { 96 u_int seeded; /* 0 causes blocking 1 allows normal output */ 97 struct selinfo rsel; /* For poll(2) */ 98 } random_systat; 99 100 /* <0 to end the kthread, 0 to let it run */ 101 static int random_kthread_control = 0; 102 103 static struct proc *random_kthread_proc; 104 105 /* For use with make_dev(9)/destroy_dev(9). */ 106 static dev_t random_dev; 107 static dev_t urandom_dev; 108 109 /* ARGSUSED */ 110 static int 111 random_check_boolean(SYSCTL_HANDLER_ARGS) 112 { 113 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 114 *(u_int *)(oidp->oid_arg1) = 1; 115 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 116 } 117 118 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 119 0, "Random Number Generator"); 120 SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW, 121 0, "Entropy Device Parameters"); 122 SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded, 123 CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1, 124 random_check_boolean, "I", "Seeded State"); 125 SYSCTL_NODE(_kern_random_sys, OID_AUTO, harvest, CTLFLAG_RW, 126 0, "Entropy Sources"); 127 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, ethernet, 128 CTLTYPE_INT|CTLFLAG_RW, &harvest.ethernet, 0, 129 random_check_boolean, "I", "Harvest NIC entropy"); 130 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, point_to_point, 131 CTLTYPE_INT|CTLFLAG_RW, &harvest.point_to_point, 0, 132 random_check_boolean, "I", "Harvest serial net entropy"); 133 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, interrupt, 134 CTLTYPE_INT|CTLFLAG_RW, &harvest.interrupt, 0, 135 random_check_boolean, "I", "Harvest IRQ entropy"); 136 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, swi, 137 CTLTYPE_INT|CTLFLAG_RW, &harvest.swi, 0, 138 random_check_boolean, "I", "Harvest SWI entropy"); 139 140 /* ARGSUSED */ 141 static int 142 random_close(dev_t dev __unused, int flags, int fmt __unused, struct thread *td) 143 { 144 if (flags & FWRITE) { 145 if (suser(td) == 0 && securelevel_gt(td->td_ucred, 0) == 0) 146 random_reseed(); 147 } 148 return 0; 149 } 150 151 /* ARGSUSED */ 152 static int 153 random_read(dev_t dev __unused, struct uio *uio, int flag) 154 { 155 int c, ret; 156 int error = 0; 157 void *random_buf; 158 159 while (!random_systat.seeded) { 160 if (flag & IO_NDELAY) 161 error = EWOULDBLOCK; 162 else 163 error = tsleep(&random_systat, PUSER|PCATCH, 164 "block", 0); 165 if (error != 0) 166 return error; 167 } 168 c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE; 169 random_buf = (void *)malloc((u_long)c, M_TEMP, M_WAITOK); 170 while (uio->uio_resid > 0 && error == 0) { 171 ret = read_random_real(random_buf, c); 172 error = uiomove(random_buf, ret, uio); 173 } 174 free(random_buf, M_TEMP); 175 return error; 176 } 177 178 /* ARGSUSED */ 179 static int 180 random_write(dev_t dev __unused, struct uio *uio, int flag __unused) 181 { 182 int c; 183 int error; 184 void *random_buf; 185 186 error = 0; 187 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 188 while (uio->uio_resid > 0) { 189 c = (int)(uio->uio_resid < PAGE_SIZE 190 ? uio->uio_resid 191 : PAGE_SIZE); 192 error = uiomove(random_buf, c, uio); 193 if (error) 194 break; 195 random_write_internal(random_buf, c); 196 } 197 free(random_buf, M_TEMP); 198 return error; 199 } 200 201 /* ARGSUSED */ 202 static int 203 random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused, 204 int flags __unused, struct thread *td __unused) 205 { 206 switch (cmd) { 207 /* Really handled in upper layer */ 208 case FIOASYNC: 209 case FIONBIO: 210 return 0; 211 default: 212 return ENOTTY; 213 } 214 } 215 216 /* ARGSUSED */ 217 static int 218 random_poll(dev_t dev __unused, int events, struct thread *td) 219 { 220 int revents; 221 222 revents = 0; 223 if (events & (POLLIN | POLLRDNORM)) { 224 if (random_systat.seeded) 225 revents = events & (POLLIN | POLLRDNORM); 226 else 227 selrecord(td, &random_systat.rsel); 228 } 229 return revents; 230 } 231 232 /* ARGSUSED */ 233 static int 234 random_modevent(module_t mod __unused, int type, void *data __unused) 235 { 236 int error, i; 237 struct harvest *np; 238 239 switch(type) { 240 case MOD_LOAD: 241 random_init(); 242 243 /* This can be turned off by the very paranoid 244 * a reseed will turn it back on. 245 */ 246 random_systat.seeded = 1; 247 248 /* Initialise the harvest fifos */ 249 STAILQ_INIT(&emptyfifo.head); 250 emptyfifo.count = 0; 251 mtx_init(&emptyfifo.lock, "entropy harvest buffers", NULL, 252 MTX_SPIN); 253 for (i = 0; i < EMPTYBUFFERS; i++) { 254 np = malloc(sizeof(struct harvest), M_ENTROPY, 255 M_WAITOK); 256 STAILQ_INSERT_TAIL(&emptyfifo.head, np, next); 257 } 258 for (i = 0; i < ENTROPYSOURCE; i++) { 259 STAILQ_INIT(&harvestfifo[i].head); 260 harvestfifo[i].count = 0; 261 mtx_init(&harvestfifo[i].lock, "entropy harvest", NULL, 262 MTX_SPIN); 263 } 264 265 if (bootverbose) 266 printf("random: <entropy source>\n"); 267 random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT, 268 GID_WHEEL, 0666, "random"); 269 urandom_dev = make_dev_alias(random_dev, "urandom"); 270 271 /* Start the hash/reseed thread */ 272 error = kthread_create(random_kthread, NULL, 273 &random_kthread_proc, RFHIGHPID, 0, "random"); 274 if (error != 0) 275 return error; 276 277 /* Register the randomness harvesting routine */ 278 random_init_harvester(random_harvest_internal, 279 read_random_real); 280 281 return 0; 282 283 case MOD_UNLOAD: 284 /* Deregister the randomness harvesting routine */ 285 random_deinit_harvester(); 286 287 /* Command the hash/reseed thread to end and 288 * wait for it to finish 289 */ 290 random_kthread_control = -1; 291 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 292 293 /* Destroy the harvest fifos */ 294 while (!STAILQ_EMPTY(&emptyfifo.head)) { 295 np = STAILQ_FIRST(&emptyfifo.head); 296 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 297 free(np, M_ENTROPY); 298 } 299 mtx_destroy(&emptyfifo.lock); 300 for (i = 0; i < ENTROPYSOURCE; i++) { 301 while (!STAILQ_EMPTY(&harvestfifo[i].head)) { 302 np = STAILQ_FIRST(&harvestfifo[i].head); 303 STAILQ_REMOVE_HEAD(&harvestfifo[i].head, next); 304 free(np, M_ENTROPY); 305 } 306 mtx_destroy(&harvestfifo[i].lock); 307 } 308 309 random_deinit(); 310 311 destroy_dev(random_dev); 312 destroy_dev(urandom_dev); 313 return 0; 314 315 case MOD_SHUTDOWN: 316 return 0; 317 318 default: 319 return EOPNOTSUPP; 320 } 321 } 322 323 DEV_MODULE(random, random_modevent, NULL); 324 325 /* ARGSUSED */ 326 static void 327 random_kthread(void *arg __unused) 328 { 329 struct harvest *event = NULL; 330 int found, active; 331 enum esource source; 332 333 /* Process until told to stop */ 334 for (; random_kthread_control == 0;) { 335 336 active = 0; 337 338 /* Cycle through all the entropy sources */ 339 for (source = 0; source < ENTROPYSOURCE; source++) { 340 341 found = 0; 342 343 /* Lock up queue draining */ 344 mtx_lock_spin(&harvestfifo[source].lock); 345 346 if (!STAILQ_EMPTY(&harvestfifo[source].head)) { 347 348 /* Get a harvested entropy event */ 349 harvestfifo[source].count--; 350 event = STAILQ_FIRST(&harvestfifo[source].head); 351 STAILQ_REMOVE_HEAD(&harvestfifo[source].head, 352 next); 353 354 active = found = 1; 355 356 } 357 358 /* Unlock the queue */ 359 mtx_unlock_spin(&harvestfifo[source].lock); 360 361 /* Deal with the event and dispose of it */ 362 if (found) { 363 364 random_process_event(event); 365 366 /* Lock the empty event buffer fifo */ 367 mtx_lock_spin(&emptyfifo.lock); 368 369 STAILQ_INSERT_TAIL(&emptyfifo.head, event, next); 370 371 mtx_unlock_spin(&emptyfifo.lock); 372 373 } 374 375 } 376 377 /* Found nothing, so don't belabour the issue */ 378 if (!active) 379 tsleep(&harvestfifo, PUSER, "-", hz/10); 380 381 } 382 383 random_set_wakeup_exit(&random_kthread_control); 384 /* NOTREACHED */ 385 } 386 387 /* Entropy harvesting routine. This is supposed to be fast; do 388 * not do anything slow in here! 389 */ 390 static void 391 random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count, 392 u_int bits, u_int frac, enum esource origin) 393 { 394 struct harvest *event; 395 396 /* Lock the particular fifo */ 397 mtx_lock_spin(&harvestfifo[origin].lock); 398 399 /* Don't make the harvest queues too big - help to prevent 400 * low-grade entropy swamping 401 */ 402 if (harvestfifo[origin].count < RANDOM_FIFO_MAX) { 403 404 /* Lock the empty event buffer fifo */ 405 mtx_lock_spin(&emptyfifo.lock); 406 407 if (!STAILQ_EMPTY(&emptyfifo.head)) { 408 event = STAILQ_FIRST(&emptyfifo.head); 409 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 410 } 411 else 412 event = NULL; 413 414 mtx_unlock_spin(&emptyfifo.lock); 415 416 /* If we didn't obtain a buffer, tough */ 417 if (event) { 418 419 /* Add the harvested data to the fifo */ 420 harvestfifo[origin].count++; 421 event->somecounter = somecounter; 422 event->size = count; 423 event->bits = bits; 424 event->frac = frac; 425 event->source = origin; 426 427 /* XXXX Come back and make this dynamic! */ 428 count = count > HARVESTSIZE ? HARVESTSIZE : count; 429 memcpy(event->entropy, entropy, count); 430 431 STAILQ_INSERT_TAIL(&harvestfifo[origin].head, event, next); 432 } 433 434 } 435 436 mtx_unlock_spin(&harvestfifo[origin].lock); 437 438 } 439 440 static void 441 random_write_internal(void *buf, int count) 442 { 443 int i; 444 u_int chunk; 445 446 /* Break the input up into HARVESTSIZE chunks. 447 * The writer has too much control here, so "estimate" the 448 * the entropy as zero. 449 */ 450 for (i = 0; i < count; i += HARVESTSIZE) { 451 chunk = HARVESTSIZE; 452 if (i + chunk >= count) 453 chunk = (u_int)(count - i); 454 random_harvest_internal(get_cyclecount(), (char *)buf + i, 455 chunk, 0, 0, RANDOM_WRITE); 456 } 457 } 458 459 void 460 random_unblock(void) 461 { 462 if (!random_systat.seeded) { 463 random_systat.seeded = 1; 464 selwakeuppri(&random_systat.rsel, PUSER); 465 wakeup(&random_systat); 466 } 467 } 468