randomdev.c revision 83366
1/*- 2 * Copyright (c) 2000 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 * $FreeBSD: head/sys/dev/random/randomdev.c 83366 2001-09-12 08:38:13Z julian $ 27 */ 28 29#include <sys/param.h> 30#include <sys/systm.h> 31#include <sys/bus.h> 32#include <sys/conf.h> 33#include <sys/fcntl.h> 34#include <sys/filio.h> 35#include <sys/kernel.h> 36#include <sys/kthread.h> 37#include <sys/lock.h> 38#include <sys/malloc.h> 39#include <sys/module.h> 40#include <sys/mutex.h> 41#include <sys/poll.h> 42#include <sys/proc.h> 43#include <sys/queue.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#include <machine/resource.h> 54 55#include <dev/random/randomdev.h> 56 57static d_open_t random_open; 58static d_close_t random_close; 59static d_read_t random_read; 60static d_write_t random_write; 61static d_ioctl_t random_ioctl; 62static d_poll_t random_poll; 63 64#define CDEV_MAJOR 2 65#define RANDOM_MINOR 3 66 67static struct cdevsw random_cdevsw = { 68 /* open */ random_open, 69 /* close */ random_close, 70 /* read */ random_read, 71 /* write */ random_write, 72 /* ioctl */ random_ioctl, 73 /* poll */ random_poll, 74 /* mmap */ nommap, 75 /* strategy */ nostrategy, 76 /* name */ "random", 77 /* maj */ CDEV_MAJOR, 78 /* dump */ nodump, 79 /* psize */ nopsize, 80 /* flags */ 0, 81}; 82 83static void random_kthread(void *); 84static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource); 85static void random_write_internal(void *, u_int); 86 87/* Ring buffer holding harvested entropy */ 88static struct harvestring { 89 volatile u_int head; 90 volatile u_int tail; 91 struct harvest data[HARVEST_RING_SIZE]; 92} harvestring; 93 94static struct random_systat { 95 u_int seeded; /* 0 causes blocking 1 allows normal output */ 96 u_int burst; /* number of events to do before sleeping */ 97 struct selinfo rsel; /* For poll(2) */ 98} random_systat; 99 100/* <0 to end the kthread, 0 to let it run */ 101static int random_kthread_control = 0; 102 103static struct proc *random_kthread_proc; 104 105/* For use with make_dev(9)/destroy_dev(9). */ 106static dev_t random_dev; 107static dev_t urandom_dev; 108 109static int 110random_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 117RANDOM_CHECK_UINT(burst, 0, 20); 118 119SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 120 0, "Random Number Generator"); 121SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW, 122 0, "Entropy Device Parameters"); 123SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded, 124 CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1, 125 random_check_boolean, "I", "Seeded State"); 126SYSCTL_PROC(_kern_random_sys, OID_AUTO, burst, 127 CTLTYPE_INT|CTLFLAG_RW, &random_systat.burst, 20, 128 random_check_uint_burst, "I", "Harvest Burst Size"); 129SYSCTL_NODE(_kern_random_sys, OID_AUTO, harvest, CTLFLAG_RW, 130 0, "Entropy Sources"); 131SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, ethernet, 132 CTLTYPE_INT|CTLFLAG_RW, &harvest.ethernet, 0, 133 random_check_boolean, "I", "Harvest NIC entropy"); 134SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, point_to_point, 135 CTLTYPE_INT|CTLFLAG_RW, &harvest.point_to_point, 0, 136 random_check_boolean, "I", "Harvest serial net entropy"); 137SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, interrupt, 138 CTLTYPE_INT|CTLFLAG_RW, &harvest.interrupt, 0, 139 random_check_boolean, "I", "Harvest IRQ entropy"); 140 141static int 142random_open(dev_t dev, int flags, int fmt, struct thread *td) 143{ 144 if ((flags & FWRITE) && (securelevel > 0 || suser(td->td_proc))) 145 return EPERM; 146 else 147 return 0; 148} 149 150static int 151random_close(dev_t dev, int flags, int fmt, struct thread *td) 152{ 153 if ((flags & FWRITE) && !(securelevel > 0 || suser(td->td_proc))) 154 random_reseed(); 155 return 0; 156} 157 158static int 159random_read(dev_t dev, struct uio *uio, int flag) 160{ 161 u_int c, ret; 162 int error = 0; 163 void *random_buf; 164 165 while (!random_systat.seeded) { 166 if (flag & IO_NDELAY) 167 error = EWOULDBLOCK; 168 else 169 error = tsleep(&random_systat, PUSER|PCATCH, 170 "block", 0); 171 if (error != 0) 172 return error; 173 } 174 c = min(uio->uio_resid, PAGE_SIZE); 175 random_buf = (void *)malloc(c, M_TEMP, M_WAITOK); 176 while (uio->uio_resid > 0 && error == 0) { 177 ret = read_random_real(random_buf, c); 178 error = uiomove(random_buf, ret, uio); 179 } 180 free(random_buf, M_TEMP); 181 return error; 182} 183 184static int 185random_write(dev_t dev, struct uio *uio, int flag) 186{ 187 u_int c; 188 int error; 189 void *random_buf; 190 191 error = 0; 192 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 193 while (uio->uio_resid > 0) { 194 c = min(uio->uio_resid, PAGE_SIZE); 195 error = uiomove(random_buf, c, uio); 196 if (error) 197 break; 198 random_write_internal(random_buf, c); 199 } 200 free(random_buf, M_TEMP); 201 return error; 202} 203 204static int 205random_ioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct thread *td) 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 217static int 218random_poll(dev_t dev, 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(curthread, &random_systat.rsel); 228 } 229 return revents; 230} 231 232static int 233random_modevent(module_t mod, int type, void *data) 234{ 235 int error; 236 237 switch(type) { 238 case MOD_LOAD: 239 random_init(); 240 241 /* This can be turned off by the very paranoid 242 * a reseed will turn it back on. 243 */ 244 random_systat.seeded = 1; 245 246 /* Number of envents to process off the harvest 247 * queue before giving it a break and sleeping 248 */ 249 random_systat.burst = 20; 250 251 /* Initialise the harvest ringbuffer */ 252 harvestring.head = 0; 253 harvestring.tail = 0; 254 255 if (bootverbose) 256 printf("random: <entropy source>\n"); 257 random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT, 258 GID_WHEEL, 0666, "random"); 259 urandom_dev = make_dev_alias(random_dev, "urandom"); 260 261 /* Start the hash/reseed thread */ 262 error = kthread_create(random_kthread, NULL, 263 &random_kthread_proc, RFHIGHPID, "random"); 264 if (error != 0) 265 return error; 266 267 /* Register the randomness harvesting routine */ 268 random_init_harvester(random_harvest_internal, 269 read_random_real); 270 271 return 0; 272 273 case MOD_UNLOAD: 274 /* Deregister the randomness harvesting routine */ 275 random_deinit_harvester(); 276 277 /* Command the hash/reseed thread to end and 278 * wait for it to finish 279 */ 280 random_kthread_control = -1; 281 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 282 283 random_deinit(); 284 285 destroy_dev(random_dev); 286 destroy_dev(urandom_dev); 287 return 0; 288 289 case MOD_SHUTDOWN: 290 return 0; 291 292 default: 293 return EOPNOTSUPP; 294 } 295} 296 297DEV_MODULE(random, random_modevent, NULL); 298 299static void 300random_kthread(void *arg /* NOTUSED */) 301{ 302 struct harvest *event; 303 int newtail, burst; 304 305 /* Drain the harvest queue (in 'burst' size chunks, 306 * if 'burst' > 0. If 'burst' == 0, then completely 307 * drain the queue. 308 */ 309 for (burst = 0; ; burst++) { 310 311 if ((harvestring.tail == harvestring.head) || 312 (random_systat.burst && burst == random_systat.burst)) { 313 tsleep(&harvestring, PUSER, "sleep", hz/10); 314 burst = 0; 315 316 } 317 else { 318 319 /* Suck a harvested entropy event out of the queue and 320 * hand it to the event processor 321 */ 322 323 newtail = (harvestring.tail + 1) & HARVEST_RING_MASK; 324 event = &harvestring.data[harvestring.tail]; 325 326 /* Bump the ring counter. This action is assumed 327 * to be atomic. 328 */ 329 harvestring.tail = newtail; 330 331 random_process_event(event); 332 333 } 334 335 /* Is the thread scheduled for a shutdown? */ 336 if (random_kthread_control != 0) { 337#ifdef DEBUG 338 mtx_lock(&Giant); 339 printf("Random kthread setting terminate\n"); 340 mtx_unlock(&Giant); 341#endif 342 random_set_wakeup_exit(&random_kthread_control); 343 /* NOTREACHED */ 344 break; 345 } 346 347 } 348 349} 350 351/* Entropy harvesting routine. This is supposed to be fast; do 352 * not do anything slow in here! 353 */ 354static void 355random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count, 356 u_int bits, u_int frac, enum esource origin) 357{ 358 struct harvest *harvest; 359 int newhead; 360 361 newhead = (harvestring.head + 1) & HARVEST_RING_MASK; 362 363 if (newhead != harvestring.tail) { 364 365 /* Add the harvested data to the ring buffer */ 366 367 harvest = &harvestring.data[harvestring.head]; 368 369 /* Stuff the harvested data into the ring */ 370 harvest->somecounter = somecounter; 371 count = count > HARVESTSIZE ? HARVESTSIZE : count; 372 memcpy(harvest->entropy, entropy, count); 373 harvest->size = count; 374 harvest->bits = bits; 375 harvest->frac = frac; 376 harvest->source = origin < ENTROPYSOURCE ? origin : 0; 377 378 /* Bump the ring counter. This action is assumed 379 * to be atomic. 380 */ 381 harvestring.head = newhead; 382 383 } 384 385} 386 387static void 388random_write_internal(void *buf, u_int count) 389{ 390 u_int i; 391 392 /* Break the input up into HARVESTSIZE chunks. 393 * The writer has too much control here, so "estimate" the 394 * the entropy as zero. 395 */ 396 for (i = 0; i < count; i += HARVESTSIZE) { 397 random_harvest_internal(get_cyclecount(), (char *)buf + i, 398 HARVESTSIZE, 0, 0, RANDOM_WRITE); 399 } 400 401 /* Maybe the loop iterated at least once */ 402 if (i > count) 403 i -= HARVESTSIZE; 404 405 /* Get the last bytes even if the input length is not 406 * a multiple of HARVESTSIZE. 407 */ 408 count %= HARVESTSIZE; 409 if (count) { 410 random_harvest_internal(get_cyclecount(), (char *)buf + i, 411 count, 0, 0, RANDOM_WRITE); 412 } 413} 414 415void 416random_unblock(void) 417{ 418 if (!random_systat.seeded) { 419 random_systat.seeded = 1; 420 selwakeup(&random_systat.rsel); 421 wakeup(&random_systat); 422 } 423} 424