1 /*- 2 * Copyright (c) 2000-2015 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/module.h> 41 #include <sys/malloc.h> 42 #include <sys/poll.h> 43 #include <sys/proc.h> 44 #include <sys/random.h> 45 #include <sys/sbuf.h> 46 #include <sys/selinfo.h> 47 #include <sys/sysctl.h> 48 #include <sys/systm.h> 49 #include <sys/uio.h> 50 #include <sys/unistd.h> 51 52 #include <crypto/rijndael/rijndael-api-fst.h> 53 #include <crypto/sha2/sha2.h> 54 55 #include <dev/random/hash.h> 56 #include <dev/random/randomdev.h> 57 #include <dev/random/random_harvestq.h> 58 59 #include "opt_random.h" 60 61 #if defined(RANDOM_DUMMY) && defined(RANDOM_YARROW) 62 #error "Cannot define both RANDOM_DUMMY and RANDOM_YARROW" 63 #endif 64 65 #define RANDOM_UNIT 0 66 67 static d_read_t randomdev_read; 68 static d_write_t randomdev_write; 69 static d_poll_t randomdev_poll; 70 static d_ioctl_t randomdev_ioctl; 71 72 static struct cdevsw random_cdevsw = { 73 .d_name = "random", 74 .d_version = D_VERSION, 75 .d_read = randomdev_read, 76 .d_write = randomdev_write, 77 .d_poll = randomdev_poll, 78 .d_ioctl = randomdev_ioctl, 79 }; 80 81 /* For use with make_dev(9)/destroy_dev(9). */ 82 static struct cdev *random_dev; 83 84 /* Set up the sysctl root node for the entropy device */ 85 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 0, "Cryptographically Secure Random Number Generator"); 86 87 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers and data structures"); 88 89 #if defined(RANDOM_DUMMY) 90 91 /*- 92 * Dummy "always block" pseudo algorithm, used when there is no real 93 * random(4) driver to provide a CSPRNG. 94 */ 95 96 static u_int 97 dummy_random_zero(void) 98 { 99 100 return (0); 101 } 102 103 static void 104 dummy_random(void) 105 { 106 } 107 108 struct random_algorithm random_alg_context = { 109 .ra_ident = "Dummy", 110 .ra_init_alg = NULL, 111 .ra_deinit_alg = NULL, 112 .ra_pre_read = dummy_random, 113 .ra_read = (random_alg_read_t *)dummy_random_zero, 114 .ra_write = (random_alg_write_t *)dummy_random_zero, 115 .ra_reseed = dummy_random, 116 .ra_seeded = (random_alg_seeded_t *)dummy_random_zero, 117 .ra_event_processor = NULL, 118 .ra_poolcount = 0, 119 }; 120 121 #else /* !defined(RANDOM_DUMMY) */ 122 123 LIST_HEAD(sources_head, random_sources); 124 static struct sources_head source_list = LIST_HEAD_INITIALIZER(source_list); 125 static u_int read_rate; 126 127 static void 128 random_alg_context_ra_init_alg(void *data) 129 { 130 131 random_alg_context.ra_init_alg(data); 132 } 133 134 static void 135 random_alg_context_ra_deinit_alg(void *data) 136 { 137 138 random_alg_context.ra_deinit_alg(data); 139 } 140 141 SYSINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_init_alg, NULL); 142 SYSUNINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_deinit_alg, NULL); 143 144 #endif /* defined(RANDOM_DUMMY) */ 145 146 static struct selinfo rsel; 147 148 /* 149 * This is the read uio(9) interface for random(4). 150 */ 151 /* ARGSUSED */ 152 static int 153 randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags) 154 { 155 156 return (read_random_uio(uio, (flags & O_NONBLOCK) != 0)); 157 } 158 159 int 160 read_random_uio(struct uio *uio, bool nonblock) 161 { 162 uint8_t *random_buf; 163 int error; 164 ssize_t read_len, total_read, c; 165 166 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 167 random_alg_context.ra_pre_read(); 168 /* (Un)Blocking logic */ 169 error = 0; 170 while (!random_alg_context.ra_seeded()) { 171 if (flags & O_NONBLOCK) { 172 error = EWOULDBLOCK; 173 break; 174 } 175 tsleep(&random_alg_context, 0, "randseed", hz/10); 176 /* keep tapping away at the pre-read until we seed/unblock. */ 177 random_alg_context.ra_pre_read(); 178 printf("random: %s unblock wait\n", __func__); 179 } 180 if (error == 0) { 181 #if !defined(RANDOM_DUMMY) 182 /* XXX: FIX!! Next line as an atomic operation? */ 183 read_rate += (uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t); 184 #endif 185 total_read = 0; 186 while (uio->uio_resid && !error) { 187 read_len = uio->uio_resid; 188 /* 189 * Belt-and-braces. 190 * Round up the read length to a crypto block size multiple, 191 * which is what the underlying generator is expecting. 192 * See the random_buf size requirements in the Yarrow/Fortuna code. 193 */ 194 read_len += RANDOM_BLOCKSIZE; 195 read_len -= read_len % RANDOM_BLOCKSIZE; 196 read_len = MIN(read_len, PAGE_SIZE); 197 random_alg_context.ra_read(random_buf, read_len); 198 c = MIN(uio->uio_resid, read_len); 199 error = uiomove(random_buf, c, uio); 200 total_read += c; 201 } 202 if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR) ) 203 /* Return partial read, not error. */ 204 error = 0; 205 } 206 free(random_buf, M_ENTROPY); 207 return (error); 208 } 209 210 /*- 211 * Kernel API version of read_random(). 212 * This is similar to random_alg_read(), 213 * except it doesn't interface with uio(9). 214 * It cannot assumed that random_buf is a multiple of 215 * RANDOM_BLOCKSIZE bytes. 216 */ 217 u_int 218 read_random(void *random_buf, u_int len) 219 { 220 u_int read_len, total_read, c; 221 uint8_t local_buf[len + RANDOM_BLOCKSIZE]; 222 223 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); 224 random_alg_context.ra_pre_read(); 225 /* (Un)Blocking logic; if not seeded, return nothing. */ 226 if (random_alg_context.ra_seeded()) { 227 #if !defined(RANDOM_DUMMY) 228 /* XXX: FIX!! Next line as an atomic operation? */ 229 read_rate += (len + sizeof(uint32_t))/sizeof(uint32_t); 230 #endif 231 read_len = len; 232 /* 233 * Belt-and-braces. 234 * Round up the read length to a crypto block size multiple, 235 * which is what the underlying generator is expecting. 236 */ 237 read_len += RANDOM_BLOCKSIZE; 238 read_len -= read_len % RANDOM_BLOCKSIZE; 239 total_read = 0; 240 while (read_len) { 241 c = MIN(read_len, PAGE_SIZE); 242 random_alg_context.ra_read(&local_buf[total_read], c); 243 read_len -= c; 244 total_read += c; 245 } 246 memcpy(random_buf, local_buf, len); 247 } else 248 len = 0; 249 return (len); 250 } 251 252 /* ARGSUSED */ 253 static int 254 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 255 { 256 uint8_t *random_buf; 257 int c, error = 0; 258 ssize_t nbytes; 259 260 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 261 nbytes = uio->uio_resid; 262 while (uio->uio_resid > 0 && error == 0) { 263 c = MIN(uio->uio_resid, PAGE_SIZE); 264 error = uiomove(random_buf, c, uio); 265 if (error) 266 break; 267 random_alg_context.ra_write(random_buf, c); 268 tsleep(&random_alg_context, 0, "randwr", hz/10); 269 } 270 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR)) 271 /* Partial write, not error. */ 272 error = 0; 273 free(random_buf, M_ENTROPY); 274 return (error); 275 } 276 277 /* ARGSUSED */ 278 static int 279 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused) 280 { 281 282 if (events & (POLLIN | POLLRDNORM)) { 283 if (random_alg_context.ra_seeded()) 284 events &= (POLLIN | POLLRDNORM); 285 else 286 selrecord(td, &rsel); 287 } 288 return (events); 289 } 290 291 /* This will be called by the entropy processor when it seeds itself and becomes secure */ 292 void 293 randomdev_unblock(void) 294 { 295 296 selwakeuppri(&rsel, PUSER); 297 wakeup(&random_alg_context); 298 printf("random: unblocking device.\n"); 299 /* Do random(9) a favour while we are about it. */ 300 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE); 301 } 302 303 /* ARGSUSED */ 304 static int 305 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 306 int flags __unused, struct thread *td __unused) 307 { 308 int error = 0; 309 310 switch (cmd) { 311 /* Really handled in upper layer */ 312 case FIOASYNC: 313 case FIONBIO: 314 break; 315 default: 316 error = ENOTTY; 317 } 318 319 return (error); 320 } 321 322 void 323 random_source_register(struct random_source *rsource) 324 { 325 #if defined(RANDOM_DUMMY) 326 (void)rsource; 327 #else /* !defined(RANDOM_DUMMY) */ 328 struct random_sources *rrs; 329 330 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 331 332 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); 333 rrs->rrs_source = rsource; 334 335 printf("random: registering fast source %s\n", rsource->rs_ident); 336 LIST_INSERT_HEAD(&source_list, rrs, rrs_entries); 337 #endif /* defined(RANDOM_DUMMY) */ 338 } 339 340 void 341 random_source_deregister(struct random_source *rsource) 342 { 343 #if defined(RANDOM_DUMMY) 344 (void)rsource; 345 #else /* !defined(RANDOM_DUMMY) */ 346 struct random_sources *rrs = NULL; 347 348 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 349 LIST_FOREACH(rrs, &source_list, rrs_entries) 350 if (rrs->rrs_source == rsource) { 351 LIST_REMOVE(rrs, rrs_entries); 352 break; 353 } 354 if (rrs != NULL) 355 free(rrs, M_ENTROPY); 356 #endif /* defined(RANDOM_DUMMY) */ 357 } 358 359 #if !defined(RANDOM_DUMMY) 360 /* 361 * Run through all fast sources reading entropy for the given 362 * number of rounds, which should be a multiple of the number 363 * of entropy accumulation pools in use; 2 for Yarrow and 32 364 * for Fortuna. 365 * 366 * BEWARE!!! 367 * This function runs inside the RNG thread! Don't do anything silly! 368 */ 369 void 370 random_sources_feed(void) 371 { 372 uint32_t entropy[HARVESTSIZE]; 373 struct random_sources *rrs; 374 u_int i, n, local_read_rate; 375 376 /* 377 * Step over all of live entropy sources, and feed their output 378 * to the system-wide RNG. 379 */ 380 /* XXX: FIX!! Next lines as an atomic operation? */ 381 local_read_rate = read_rate; 382 read_rate = RANDOM_ALG_READ_RATE_MINIMUM; 383 LIST_FOREACH(rrs, &source_list, rrs_entries) { 384 for (i = 0; i < random_alg_context.ra_poolcount*local_read_rate; i++) { 385 n = rrs->rrs_source->rs_read(entropy, sizeof(entropy)); 386 KASSERT((n > 0 && n <= sizeof(entropy)), ("very bad return from rs_read (= %d) in %s", n, __func__)); 387 random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source); 388 } 389 } 390 explicit_bzero(entropy, sizeof(entropy)); 391 } 392 393 static int 394 random_source_handler(SYSCTL_HANDLER_ARGS) 395 { 396 struct random_sources *rrs; 397 struct sbuf sbuf; 398 int error, count; 399 400 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 401 count = 0; 402 LIST_FOREACH(rrs, &source_list, rrs_entries) { 403 sbuf_cat(&sbuf, (count++ ? ",'" : "'")); 404 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); 405 sbuf_cat(&sbuf, "'"); 406 } 407 error = sbuf_finish(&sbuf); 408 sbuf_delete(&sbuf); 409 return (error); 410 } 411 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 412 NULL, 0, random_source_handler, "A", 413 "List of active fast entropy sources."); 414 #endif /* !defined(RANDOM_DUMMY) */ 415 416 /* ARGSUSED */ 417 static int 418 randomdev_modevent(module_t mod __unused, int type, void *data __unused) 419 { 420 int error = 0; 421 422 switch (type) { 423 case MOD_LOAD: 424 printf("random: entropy device external interface\n"); 425 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 426 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random"); 427 make_dev_alias(random_dev, "urandom"); /* compatibility */ 428 break; 429 case MOD_UNLOAD: 430 destroy_dev(random_dev); 431 break; 432 case MOD_SHUTDOWN: 433 break; 434 default: 435 error = EOPNOTSUPP; 436 break; 437 } 438 return (error); 439 } 440 441 static moduledata_t randomdev_mod = { 442 "random_device", 443 randomdev_modevent, 444 0 445 }; 446 447 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); 448 MODULE_VERSION(random_device, 1); 449