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