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_version = D_VERSION, 68 .d_flags = D_NEEDGIANT, 69 .d_close = random_close, 70 .d_read = random_read, 71 .d_write = random_write, 72 .d_ioctl = random_ioctl, 73 .d_poll = random_poll, 74 .d_name = "random", 75 }; 76 77 static void random_kthread(void *); 78 static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource); 79 static void random_write_internal(void *, int); 80 81 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers"); 82 83 /* Lockable FIFO queue holding entropy buffers */ 84 struct entropyfifo { 85 struct mtx lock; 86 int count; 87 STAILQ_HEAD(harvestlist, harvest) head; 88 }; 89 90 /* Empty entropy buffers */ 91 static struct entropyfifo emptyfifo; 92 #define EMPTYBUFFERS 1024 93 94 /* Harvested entropy */ 95 static struct entropyfifo harvestfifo[ENTROPYSOURCE]; 96 97 static struct random_systat { 98 u_int seeded; /* 0 causes blocking 1 allows normal output */ 99 struct selinfo rsel; /* For poll(2) */ 100 } random_systat; 101 102 /* <0 to end the kthread, 0 to let it run */ 103 static int random_kthread_control = 0; 104 105 static struct proc *random_kthread_proc; 106 107 /* For use with make_dev(9)/destroy_dev(9). */ 108 static dev_t random_dev; 109 110 /* ARGSUSED */ 111 static int 112 random_check_boolean(SYSCTL_HANDLER_ARGS) 113 { 114 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 115 *(u_int *)(oidp->oid_arg1) = 1; 116 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 117 } 118 119 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 120 0, "Random Number Generator"); 121 SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW, 122 0, "Entropy Device Parameters"); 123 SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded, 124 CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1, 125 random_check_boolean, "I", "Seeded State"); 126 SYSCTL_NODE(_kern_random_sys, OID_AUTO, harvest, CTLFLAG_RW, 127 0, "Entropy Sources"); 128 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, ethernet, 129 CTLTYPE_INT|CTLFLAG_RW, &harvest.ethernet, 0, 130 random_check_boolean, "I", "Harvest NIC entropy"); 131 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, point_to_point, 132 CTLTYPE_INT|CTLFLAG_RW, &harvest.point_to_point, 0, 133 random_check_boolean, "I", "Harvest serial net entropy"); 134 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, interrupt, 135 CTLTYPE_INT|CTLFLAG_RW, &harvest.interrupt, 0, 136 random_check_boolean, "I", "Harvest IRQ entropy"); 137 SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, swi, 138 CTLTYPE_INT|CTLFLAG_RW, &harvest.swi, 0, 139 random_check_boolean, "I", "Harvest SWI entropy"); 140 141 /* ARGSUSED */ 142 static int 143 random_close(dev_t dev __unused, int flags, int fmt __unused, struct thread *td) 144 { 145 if (flags & FWRITE) { 146 if (suser(td) == 0 && securelevel_gt(td->td_ucred, 0) == 0) 147 random_reseed(); 148 } 149 return 0; 150 } 151 152 /* ARGSUSED */ 153 static int 154 random_read(dev_t dev __unused, struct uio *uio, int flag) 155 { 156 int c, ret; 157 int error = 0; 158 void *random_buf; 159 160 while (!random_systat.seeded) { 161 if (flag & IO_NDELAY) 162 error = EWOULDBLOCK; 163 else 164 error = tsleep(&random_systat, PUSER|PCATCH, 165 "block", 0); 166 if (error != 0) 167 return error; 168 } 169 c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE; 170 random_buf = (void *)malloc((u_long)c, M_TEMP, M_WAITOK); 171 while (uio->uio_resid > 0 && error == 0) { 172 ret = read_random_real(random_buf, c); 173 error = uiomove(random_buf, ret, uio); 174 } 175 free(random_buf, M_TEMP); 176 return error; 177 } 178 179 /* ARGSUSED */ 180 static int 181 random_write(dev_t dev __unused, struct uio *uio, int flag __unused) 182 { 183 int c; 184 int error; 185 void *random_buf; 186 187 error = 0; 188 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 189 while (uio->uio_resid > 0) { 190 c = (int)(uio->uio_resid < PAGE_SIZE 191 ? uio->uio_resid 192 : PAGE_SIZE); 193 error = uiomove(random_buf, c, uio); 194 if (error) 195 break; 196 random_write_internal(random_buf, c); 197 } 198 free(random_buf, M_TEMP); 199 return error; 200 } 201 202 /* ARGSUSED */ 203 static int 204 random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused, 205 int flags __unused, struct thread *td __unused) 206 { 207 switch (cmd) { 208 /* Really handled in upper layer */ 209 case FIOASYNC: 210 case FIONBIO: 211 return 0; 212 default: 213 return ENOTTY; 214 } 215 } 216 217 /* ARGSUSED */ 218 static int 219 random_poll(dev_t dev __unused, int events, struct thread *td) 220 { 221 int revents; 222 223 revents = 0; 224 if (events & (POLLIN | POLLRDNORM)) { 225 if (random_systat.seeded) 226 revents = events & (POLLIN | POLLRDNORM); 227 else 228 selrecord(td, &random_systat.rsel); 229 } 230 return revents; 231 } 232 233 /* ARGSUSED */ 234 static int 235 random_modevent(module_t mod __unused, int type, void *data __unused) 236 { 237 int error, i; 238 struct harvest *np; 239 240 switch(type) { 241 case MOD_LOAD: 242 random_init(); 243 244 /* This can be turned off by the very paranoid 245 * a reseed will turn it back on. 246 */ 247 random_systat.seeded = 1; 248 249 /* Initialise the harvest fifos */ 250 STAILQ_INIT(&emptyfifo.head); 251 emptyfifo.count = 0; 252 mtx_init(&emptyfifo.lock, "entropy harvest buffers", NULL, 253 MTX_SPIN); 254 for (i = 0; i < EMPTYBUFFERS; i++) { 255 np = malloc(sizeof(struct harvest), M_ENTROPY, 256 M_WAITOK); 257 STAILQ_INSERT_TAIL(&emptyfifo.head, np, next); 258 } 259 for (i = 0; i < ENTROPYSOURCE; i++) { 260 STAILQ_INIT(&harvestfifo[i].head); 261 harvestfifo[i].count = 0; 262 mtx_init(&harvestfifo[i].lock, "entropy harvest", NULL, 263 MTX_SPIN); 264 } 265 266 if (bootverbose) 267 printf("random: <entropy source>\n"); 268 random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT, 269 GID_WHEEL, 0666, "random"); 270 make_dev_alias(random_dev, "urandom"); 271 272 /* Start the hash/reseed thread */ 273 error = kthread_create(random_kthread, NULL, 274 &random_kthread_proc, RFHIGHPID, 0, "random"); 275 if (error != 0) 276 return error; 277 278 /* Register the randomness harvesting routine */ 279 random_init_harvester(random_harvest_internal, 280 read_random_real); 281 282 return 0; 283 284 case MOD_UNLOAD: 285 /* Deregister the randomness harvesting routine */ 286 random_deinit_harvester(); 287 288 /* Command the hash/reseed thread to end and 289 * wait for it to finish 290 */ 291 random_kthread_control = -1; 292 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 293 294 /* Destroy the harvest fifos */ 295 while (!STAILQ_EMPTY(&emptyfifo.head)) { 296 np = STAILQ_FIRST(&emptyfifo.head); 297 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 298 free(np, M_ENTROPY); 299 } 300 mtx_destroy(&emptyfifo.lock); 301 for (i = 0; i < ENTROPYSOURCE; i++) { 302 while (!STAILQ_EMPTY(&harvestfifo[i].head)) { 303 np = STAILQ_FIRST(&harvestfifo[i].head); 304 STAILQ_REMOVE_HEAD(&harvestfifo[i].head, next); 305 free(np, M_ENTROPY); 306 } 307 mtx_destroy(&harvestfifo[i].lock); 308 } 309 310 random_deinit(); 311 312 destroy_dev(random_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