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 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/queue.h> 31 #include <sys/systm.h> 32 #include <sys/conf.h> 33 #include <sys/fcntl.h> 34 #include <sys/uio.h> 35 #include <sys/kernel.h> 36 #include <sys/kthread.h> 37 #include <sys/malloc.h> 38 #include <sys/module.h> 39 #include <sys/bus.h> 40 #include <sys/poll.h> 41 #include <sys/selinfo.h> 42 #include <sys/random.h> 43 #include <sys/sysctl.h> 44 #include <sys/vnode.h> 45 #include <sys/unistd.h> 46 47 #include <machine/bus.h> 48 #include <machine/cpu.h> 49 #include <machine/resource.h> 50 51 #include <dev/random/randomdev.h> 52 53 static d_open_t random_open; 54 static d_close_t random_close; 55 static d_read_t random_read; 56 static d_write_t random_write; 57 static d_ioctl_t random_ioctl; 58 static d_poll_t random_poll; 59 60 #define CDEV_MAJOR 2 61 #define RANDOM_MINOR 3 62 63 static struct cdevsw random_cdevsw = { 64 /* open */ random_open, 65 /* close */ random_close, 66 /* read */ random_read, 67 /* write */ random_write, 68 /* ioctl */ random_ioctl, 69 /* poll */ random_poll, 70 /* mmap */ nommap, 71 /* strategy */ nostrategy, 72 /* name */ "random", 73 /* maj */ CDEV_MAJOR, 74 /* dump */ nodump, 75 /* psize */ nopsize, 76 /* flags */ 0, 77 /* bmaj */ -1 78 }; 79 80 static void random_kthread(void *); 81 static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource); 82 static void random_write_internal(void *, u_int); 83 84 /* Ring buffer holding harvested entropy */ 85 static struct harvestring { 86 volatile u_int head; 87 volatile u_int tail; 88 struct harvest data[HARVEST_RING_SIZE]; 89 } harvestring; 90 91 static struct random_systat { 92 u_int seeded; /* 0 causes blocking 1 allows normal output */ 93 u_int burst; /* number of events to do before sleeping */ 94 struct selinfo rsel; /* For poll(2) */ 95 } random_systat; 96 97 /* <0 to end the kthread, 0 to let it run */ 98 static int random_kthread_control = 0; 99 100 static struct proc *random_kthread_proc; 101 102 /* For use with make_dev(9)/destroy_dev(9). */ 103 static dev_t random_dev; 104 static dev_t urandom_dev; 105 106 static int 107 random_check_boolean(SYSCTL_HANDLER_ARGS) 108 { 109 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 110 *(u_int *)(oidp->oid_arg1) = 1; 111 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 112 } 113 114 RANDOM_CHECK_UINT(burst, 0, 20); 115 116 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 117 0, "Random Number Generator"); 118 SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW, 119 0, "Entropy Device Parameters"); 120 SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded, 121 CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1, 122 random_check_boolean, "I", "Seeded State"); 123 SYSCTL_PROC(_kern_random_sys, OID_AUTO, burst, 124 CTLTYPE_INT|CTLFLAG_RW, &random_systat.burst, 20, 125 random_check_uint_burst, "I", "Harvest Burst Size"); 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"); 137 138 static int 139 random_open(dev_t dev, int flags, int fmt, struct proc *p) 140 { 141 if ((flags & FWRITE) && (securelevel > 0 || suser(p))) 142 return EPERM; 143 else 144 return 0; 145 } 146 147 static int 148 random_close(dev_t dev, int flags, int fmt, struct proc *p) 149 { 150 if ((flags & FWRITE) && !(securelevel > 0 || suser(p))) 151 random_reseed(); 152 return 0; 153 } 154 155 static int 156 random_read(dev_t dev, struct uio *uio, int flag) 157 { 158 u_int c, ret; 159 int error = 0; 160 void *random_buf; 161 162 while (!random_systat.seeded) { 163 if (flag & IO_NDELAY) 164 error = EWOULDBLOCK; 165 else 166 error = tsleep(&random_systat, PUSER|PCATCH, 167 "block", 0); 168 if (error != 0) 169 return error; 170 } 171 c = min(uio->uio_resid, PAGE_SIZE); 172 random_buf = (void *)malloc(c, M_TEMP, M_WAITOK); 173 while (uio->uio_resid > 0 && error == 0) { 174 ret = read_random_real(random_buf, c); 175 error = uiomove(random_buf, ret, uio); 176 } 177 free(random_buf, M_TEMP); 178 return error; 179 } 180 181 static int 182 random_write(dev_t dev, struct uio *uio, int flag) 183 { 184 u_int c; 185 int error; 186 void *random_buf; 187 188 error = 0; 189 random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 190 while (uio->uio_resid > 0) { 191 c = min(uio->uio_resid, 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 static int 202 random_ioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p) 203 { 204 return ENOTTY; 205 } 206 207 static int 208 random_poll(dev_t dev, int events, struct proc *p) 209 { 210 int revents; 211 212 revents = 0; 213 if (events & (POLLIN | POLLRDNORM)) { 214 if (random_systat.seeded) 215 revents = events & (POLLIN | POLLRDNORM); 216 else 217 selrecord(p, &random_systat.rsel); 218 } 219 return revents; 220 } 221 222 static int 223 random_modevent(module_t mod, int type, void *data) 224 { 225 int error; 226 227 switch(type) { 228 case MOD_LOAD: 229 random_init(); 230 231 /* This can be turned off by the very paranoid 232 * a reseed will turn it back on. 233 */ 234 random_systat.seeded = 1; 235 236 /* Number of envents to process off the harvest 237 * queue before giving it a break and sleeping 238 */ 239 random_systat.burst = 20; 240 241 /* Initialise the harvest ringbuffer */ 242 harvestring.head = 0; 243 harvestring.tail = 0; 244 245 if (bootverbose) 246 printf("random: <entropy source>\n"); 247 random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT, 248 GID_WHEEL, 0666, "random"); 249 urandom_dev = make_dev_alias(random_dev, "urandom"); 250 251 /* Start the hash/reseed thread */ 252 error = kthread_create(random_kthread, NULL, 253 &random_kthread_proc, RFHIGHPID, "random"); 254 if (error != 0) 255 return error; 256 257 /* Register the randomness harvesting routine */ 258 random_init_harvester(random_harvest_internal, 259 read_random_real); 260 261 return 0; 262 263 case MOD_UNLOAD: 264 /* Deregister the randomness harvesting routine */ 265 random_deinit_harvester(); 266 267 /* Command the hash/reseed thread to end and 268 * wait for it to finish 269 */ 270 random_kthread_control = -1; 271 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 272 273 random_deinit(); 274 275 destroy_dev(random_dev); 276 destroy_dev(urandom_dev); 277 return 0; 278 279 case MOD_SHUTDOWN: 280 return 0; 281 282 default: 283 return EOPNOTSUPP; 284 } 285 } 286 287 DEV_MODULE(random, random_modevent, NULL); 288 289 static void 290 random_kthread(void *arg /* NOTUSED */) 291 { 292 struct harvest *event; 293 int newtail, burst; 294 295 /* Drain the harvest queue (in 'burst' size chunks, 296 * if 'burst' > 0. If 'burst' == 0, then completely 297 * drain the queue. 298 */ 299 for (burst = 0; ; burst++) { 300 301 if ((harvestring.tail == harvestring.head) || 302 (random_systat.burst && burst == random_systat.burst)) { 303 tsleep(&harvestring, PUSER, "sleep", hz/10); 304 burst = 0; 305 306 } 307 else { 308 309 /* Suck a harvested entropy event out of the queue and 310 * hand it to the event processor 311 */ 312 313 newtail = (harvestring.tail + 1) & HARVEST_RING_MASK; 314 event = &harvestring.data[harvestring.tail]; 315 316 /* Bump the ring counter. This action is assumed 317 * to be atomic. 318 */ 319 harvestring.tail = newtail; 320 321 random_process_event(event); 322 323 } 324 325 /* Is the thread scheduled for a shutdown? */ 326 if (random_kthread_control != 0) { 327 #ifdef DEBUG 328 mtx_lock(&Giant); 329 printf("Random kthread setting terminate\n"); 330 mtx_unlock(&Giant); 331 #endif 332 random_set_wakeup_exit(&random_kthread_control); 333 /* NOTREACHED */ 334 break; 335 } 336 337 } 338 339 } 340 341 /* Entropy harvesting routine. This is supposed to be fast; do 342 * not do anything slow in here! 343 */ 344 static void 345 random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count, 346 u_int bits, u_int frac, enum esource origin) 347 { 348 struct harvest *harvest; 349 int newhead; 350 351 newhead = (harvestring.head + 1) & HARVEST_RING_MASK; 352 353 if (newhead != harvestring.tail) { 354 355 /* Add the harvested data to the ring buffer */ 356 357 harvest = &harvestring.data[harvestring.head]; 358 359 /* Stuff the harvested data into the ring */ 360 harvest->somecounter = somecounter; 361 count = count > HARVESTSIZE ? HARVESTSIZE : count; 362 memcpy(harvest->entropy, entropy, count); 363 harvest->size = count; 364 harvest->bits = bits; 365 harvest->frac = frac; 366 harvest->source = origin < ENTROPYSOURCE ? origin : 0; 367 368 /* Bump the ring counter. This action is assumed 369 * to be atomic. 370 */ 371 harvestring.head = newhead; 372 373 } 374 375 } 376 377 static void 378 random_write_internal(void *buf, u_int count) 379 { 380 u_int i; 381 382 /* Break the input up into HARVESTSIZE chunks. 383 * The writer has too much control here, so "estimate" the 384 * the entropy as zero. 385 */ 386 for (i = 0; i < count; i += HARVESTSIZE) { 387 random_harvest_internal(get_cyclecount(), (char *)buf + i, 388 HARVESTSIZE, 0, 0, RANDOM_WRITE); 389 } 390 391 /* Maybe the loop iterated at least once */ 392 if (i > count) 393 i -= HARVESTSIZE; 394 395 /* Get the last bytes even if the input length is not 396 * a multiple of HARVESTSIZE. 397 */ 398 count %= HARVESTSIZE; 399 if (count) { 400 random_harvest_internal(get_cyclecount(), (char *)buf + i, 401 count, 0, 0, RANDOM_WRITE); 402 } 403 } 404 405 void 406 random_unblock(void) 407 { 408 if (!random_systat.seeded) { 409 random_systat.seeded = 1; 410 selwakeup(&random_systat.rsel); 411 wakeup(&random_systat); 412 } 413 } 414