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 */ 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_open_t random_open; 57 static d_close_t random_close; 58 static d_read_t random_read; 59 static d_write_t random_write; 60 static d_ioctl_t random_ioctl; 61 static d_poll_t random_poll; 62 63 #define CDEV_MAJOR 2 64 #define RANDOM_MINOR 3 65 66 static struct cdevsw random_cdevsw = { 67 .d_open = random_open, 68 .d_close = random_close, 69 .d_read = random_read, 70 .d_write = random_write, 71 .d_ioctl = random_ioctl, 72 .d_poll = random_poll, 73 .d_name = "random", 74 .d_maj = CDEV_MAJOR, 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 /* Ring buffer holding harvested entropy */ 82 static struct harvestring { 83 volatile u_int head; 84 volatile u_int tail; 85 struct harvest data[HARVEST_RING_SIZE]; 86 } harvestring; 87 88 static struct random_systat { 89 u_int seeded; /* 0 causes blocking 1 allows normal output */ 90 u_int burst; /* number of events to do before sleeping */ 91 struct selinfo rsel; /* For poll(2) */ 92 } random_systat; 93 94 /* <0 to end the kthread, 0 to let it run */ 95 static int random_kthread_control = 0; 96 97 static struct proc *random_kthread_proc; 98 99 /* For use with make_dev(9)/destroy_dev(9). */ 100 static dev_t random_dev; 101 static dev_t urandom_dev; 102 103 /* ARGSUSED */ 104 static int 105 random_check_boolean(SYSCTL_HANDLER_ARGS) 106 { 107 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 108 *(u_int *)(oidp->oid_arg1) = 1; 109 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 110 } 111 112 RANDOM_CHECK_UINT(burst, 0, 20); 113 114 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 115 0, "Random Number Generator"); 116 SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW, 117 0, "Entropy Device Parameters"); 118 SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded, 119 CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1, 120 random_check_boolean, "I", "Seeded State"); 121 SYSCTL_PROC(_kern_random_sys, OID_AUTO, burst, 122 CTLTYPE_INT|CTLFLAG_RW, &random_systat.burst, 20, 123 random_check_uint_burst, "I", "Harvest Burst Size"); 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_open(dev_t dev __unused, int flags, int fmt __unused, struct thread *td) 142 { 143 int error; 144 145 if (flags & FWRITE) { 146 error = suser(td); 147 if (error) 148 return (error); 149 error = securelevel_gt(td->td_ucred, 0); 150 if (error) 151 return (error); 152 } 153 return 0; 154 } 155 156 /* ARGSUSED */ 157 static int 158 random_close(dev_t dev __unused, int flags, int fmt __unused, struct thread *td) 159 { 160 if (flags & FWRITE) { 161 if (!(suser(td) || 162 securelevel_gt(td->td_ucred, 0))) 163 random_reseed(); 164 } 165 return 0; 166 } 167 168 /* ARGSUSED */ 169 static int 170 random_read(dev_t dev __unused, struct uio *uio, int flag) 171 { 172 int c, ret; 173 int error = 0; 174 void *random_buf; 175 176 while (!random_systat.seeded) { 177 if (flag & IO_NDELAY) 178 error = EWOULDBLOCK; 179 else 180 error = tsleep(&random_systat, PUSER|PCATCH, 181 "block", 0); 182 if (error != 0) 183 return error; 184 } 185 c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE; 186 random_buf = (void *)malloc((u_long)c, M_TEMP, M_WAITOK); 187 while (uio->uio_resid > 0 && error == 0) { 188 ret = read_random_real(random_buf, c); 189 error = uiomove(random_buf, ret, uio); 190 } 191 free(random_buf, M_TEMP); 192 return error; 193 } 194 195 /* ARGSUSED */ 196 static int 197 random_write(dev_t dev __unused, struct uio *uio, int flag __unused) 198 { 199 int c; 200 int error; 201 void *random_buf; 202 203 error = 0; 204 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 205 while (uio->uio_resid > 0) { 206 c = (int)(uio->uio_resid < PAGE_SIZE 207 ? uio->uio_resid 208 : PAGE_SIZE); 209 error = uiomove(random_buf, c, uio); 210 if (error) 211 break; 212 random_write_internal(random_buf, c); 213 } 214 free(random_buf, M_TEMP); 215 return error; 216 } 217 218 /* ARGSUSED */ 219 static int 220 random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused, 221 int flags __unused, struct thread *td __unused) 222 { 223 switch (cmd) { 224 /* Really handled in upper layer */ 225 case FIOASYNC: 226 case FIONBIO: 227 return 0; 228 default: 229 return ENOTTY; 230 } 231 } 232 233 /* ARGSUSED */ 234 static int 235 random_poll(dev_t dev __unused, int events, struct thread *td) 236 { 237 int revents; 238 239 revents = 0; 240 if (events & (POLLIN | POLLRDNORM)) { 241 if (random_systat.seeded) 242 revents = events & (POLLIN | POLLRDNORM); 243 else 244 selrecord(td, &random_systat.rsel); 245 } 246 return revents; 247 } 248 249 /* ARGSUSED */ 250 static int 251 random_modevent(module_t mod __unused, int type, void *data __unused) 252 { 253 int error; 254 255 switch(type) { 256 case MOD_LOAD: 257 random_init(); 258 259 /* This can be turned off by the very paranoid 260 * a reseed will turn it back on. 261 */ 262 random_systat.seeded = 1; 263 264 /* Number of envents to process off the harvest 265 * queue before giving it a break and sleeping 266 */ 267 random_systat.burst = 20; 268 269 /* Initialise the harvest ringbuffer */ 270 harvestring.head = 0; 271 harvestring.tail = 0; 272 273 if (bootverbose) 274 printf("random: <entropy source>\n"); 275 random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT, 276 GID_WHEEL, 0666, "random"); 277 urandom_dev = make_dev_alias(random_dev, "urandom"); 278 279 /* Start the hash/reseed thread */ 280 error = kthread_create(random_kthread, NULL, 281 &random_kthread_proc, RFHIGHPID, 0, "random"); 282 if (error != 0) 283 return error; 284 285 /* Register the randomness harvesting routine */ 286 random_init_harvester(random_harvest_internal, 287 read_random_real); 288 289 return 0; 290 291 case MOD_UNLOAD: 292 /* Deregister the randomness harvesting routine */ 293 random_deinit_harvester(); 294 295 /* Command the hash/reseed thread to end and 296 * wait for it to finish 297 */ 298 random_kthread_control = -1; 299 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 300 301 random_deinit(); 302 303 destroy_dev(random_dev); 304 destroy_dev(urandom_dev); 305 return 0; 306 307 case MOD_SHUTDOWN: 308 return 0; 309 310 default: 311 return EOPNOTSUPP; 312 } 313 } 314 315 DEV_MODULE(random, random_modevent, NULL); 316 317 /* ARGSUSED */ 318 static void 319 random_kthread(void *arg __unused) 320 { 321 struct harvest *event; 322 u_int newtail, burst; 323 324 /* Drain the harvest queue (in 'burst' size chunks, 325 * if 'burst' > 0. If 'burst' == 0, then completely 326 * drain the queue. 327 */ 328 for (burst = 0; ; burst++) { 329 330 if ((harvestring.tail == harvestring.head) || 331 (random_systat.burst && burst == random_systat.burst)) { 332 tsleep(&harvestring, PUSER, "-", hz/10); 333 burst = 0; 334 335 } 336 else { 337 338 /* Suck a harvested entropy event out of the queue and 339 * hand it to the event processor 340 */ 341 342 newtail = (harvestring.tail + 1) & HARVEST_RING_MASK; 343 event = &harvestring.data[harvestring.tail]; 344 345 /* Bump the ring counter. This action is assumed 346 * to be atomic. 347 */ 348 harvestring.tail = newtail; 349 350 random_process_event(event); 351 352 } 353 354 /* Is the thread scheduled for a shutdown? */ 355 if (random_kthread_control != 0) { 356 #ifdef DEBUG 357 printf("Random kthread setting terminate\n"); 358 #endif 359 random_set_wakeup_exit(&random_kthread_control); 360 /* NOTREACHED */ 361 break; 362 } 363 364 } 365 366 } 367 368 /* Entropy harvesting routine. This is supposed to be fast; do 369 * not do anything slow in here! 370 */ 371 static void 372 random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count, 373 u_int bits, u_int frac, enum esource origin) 374 { 375 struct harvest *pharvest; 376 u_int newhead; 377 378 newhead = (harvestring.head + 1) & HARVEST_RING_MASK; 379 380 if (newhead != harvestring.tail) { 381 382 /* Add the harvested data to the ring buffer */ 383 384 pharvest = &harvestring.data[harvestring.head]; 385 386 /* Stuff the harvested data into the ring */ 387 pharvest->somecounter = somecounter; 388 count = count > HARVESTSIZE ? HARVESTSIZE : count; 389 memcpy(pharvest->entropy, entropy, count); 390 pharvest->size = count; 391 pharvest->bits = bits; 392 pharvest->frac = frac; 393 pharvest->source = 394 origin < ENTROPYSOURCE ? origin : RANDOM_START; 395 396 /* Bump the ring counter. This action is assumed 397 * to be atomic. 398 */ 399 harvestring.head = newhead; 400 401 } 402 403 } 404 405 static void 406 random_write_internal(void *buf, int count) 407 { 408 int i; 409 410 /* Break the input up into HARVESTSIZE chunks. 411 * The writer has too much control here, so "estimate" the 412 * the entropy as zero. 413 */ 414 for (i = 0; i < count; i += HARVESTSIZE) { 415 random_harvest_internal(get_cyclecount(), (char *)buf + i, 416 HARVESTSIZE, 0, 0, RANDOM_WRITE); 417 } 418 419 /* Maybe the loop iterated at least once */ 420 if (i > count) 421 i -= HARVESTSIZE; 422 423 /* Get the last bytes even if the input length is not 424 * a multiple of HARVESTSIZE. 425 */ 426 count %= HARVESTSIZE; 427 if (count) { 428 random_harvest_internal(get_cyclecount(), (char *)buf + i, 429 (u_int)count, 0, 0, RANDOM_WRITE); 430 } 431 } 432 433 void 434 random_unblock(void) 435 { 436 if (!random_systat.seeded) { 437 random_systat.seeded = 1; 438 selwakeup(&random_systat.rsel); 439 wakeup(&random_systat); 440 } 441 } 442