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 uint8_t *random_buf; 156 int c, error; 157 ssize_t nbytes; 158 159 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 160 random_alg_context.ra_pre_read(); 161 /* (Un)Blocking logic */ 162 error = 0; 163 while (!random_alg_context.ra_seeded()) { 164 if (flags & O_NONBLOCK) { 165 error = EWOULDBLOCK; 166 break; 167 } 168 tsleep(&random_alg_context, 0, "randseed", hz/10); 169 /* keep tapping away at the pre-read until we seed/unblock. */ 170 random_alg_context.ra_pre_read(); 171 printf("random: %s unblock wait\n", __func__); 172 } 173 if (error == 0) { 174 #if !defined(RANDOM_DUMMY) 175 /* XXX: FIX!! Next line as an atomic operation? */ 176 read_rate += (uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t); 177 #endif 178 nbytes = uio->uio_resid; 179 while (uio->uio_resid && !error) { 180 c = MIN(uio->uio_resid, PAGE_SIZE); 181 /* See the random_buf size requirements in the Yarrow/Fortuna code */ 182 random_alg_context.ra_read(random_buf, c); 183 error = uiomove(random_buf, c, uio); 184 } 185 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR) ) 186 /* Return partial read, not error. */ 187 error = 0; 188 } 189 free(random_buf, M_ENTROPY); 190 return (error); 191 } 192 193 /*- 194 * Kernel API version of read_random(). 195 * This is similar to random_alg_read(), 196 * except it doesn't interface with uio(9). 197 * It cannot assumed that random_buf is a multiple of 198 * RANDOM_BLOCKSIZE bytes. 199 */ 200 u_int 201 read_random(void *random_buf, u_int len) 202 { 203 u_int read_len, total_read, c; 204 uint8_t local_buf[len + RANDOM_BLOCKSIZE]; 205 206 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); 207 random_alg_context.ra_pre_read(); 208 /* (Un)Blocking logic; if not seeded, return nothing. */ 209 if (random_alg_context.ra_seeded()) { 210 #if !defined(RANDOM_DUMMY) 211 /* XXX: FIX!! Next line as an atomic operation? */ 212 read_rate += (len + sizeof(uint32_t))/sizeof(uint32_t); 213 #endif 214 read_len = len; 215 total_read = 0; 216 while (read_len) { 217 c = MIN(read_len, PAGE_SIZE); 218 random_alg_context.ra_read(&local_buf[total_read], c); 219 read_len -= c; 220 total_read += c; 221 } 222 memcpy(random_buf, local_buf, len); 223 } else 224 len = 0; 225 return (len); 226 } 227 228 /* ARGSUSED */ 229 static int 230 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 231 { 232 uint8_t *random_buf; 233 int c, error = 0; 234 ssize_t nbytes; 235 236 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 237 nbytes = uio->uio_resid; 238 while (uio->uio_resid > 0 && error == 0) { 239 c = MIN(uio->uio_resid, PAGE_SIZE); 240 error = uiomove(random_buf, c, uio); 241 if (error) 242 break; 243 random_alg_context.ra_write(random_buf, c); 244 tsleep(&random_alg_context, 0, "randwr", hz/10); 245 } 246 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR)) 247 /* Partial write, not error. */ 248 error = 0; 249 free(random_buf, M_ENTROPY); 250 return (error); 251 } 252 253 /* ARGSUSED */ 254 static int 255 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused) 256 { 257 258 if (events & (POLLIN | POLLRDNORM)) { 259 if (random_alg_context.ra_seeded()) 260 events &= (POLLIN | POLLRDNORM); 261 else 262 selrecord(td, &rsel); 263 } 264 return (events); 265 } 266 267 /* This will be called by the entropy processor when it seeds itself and becomes secure */ 268 void 269 randomdev_unblock(void) 270 { 271 272 selwakeuppri(&rsel, PUSER); 273 wakeup(&random_alg_context); 274 printf("random: unblocking device.\n"); 275 /* Do random(9) a favour while we are about it. */ 276 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE); 277 } 278 279 /* ARGSUSED */ 280 static int 281 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 282 int flags __unused, struct thread *td __unused) 283 { 284 int error = 0; 285 286 switch (cmd) { 287 /* Really handled in upper layer */ 288 case FIOASYNC: 289 case FIONBIO: 290 break; 291 default: 292 error = ENOTTY; 293 } 294 295 return (error); 296 } 297 298 void 299 random_source_register(struct random_source *rsource) 300 { 301 #if defined(RANDOM_DUMMY) 302 (void)rsource; 303 #else /* !defined(RANDOM_DUMMY) */ 304 struct random_sources *rrs; 305 306 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 307 308 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); 309 rrs->rrs_source = rsource; 310 311 printf("random: registering fast source %s\n", rsource->rs_ident); 312 LIST_INSERT_HEAD(&source_list, rrs, rrs_entries); 313 #endif /* defined(RANDOM_DUMMY) */ 314 } 315 316 void 317 random_source_deregister(struct random_source *rsource) 318 { 319 #if defined(RANDOM_DUMMY) 320 (void)rsource; 321 #else /* !defined(RANDOM_DUMMY) */ 322 struct random_sources *rrs = NULL; 323 324 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 325 LIST_FOREACH(rrs, &source_list, rrs_entries) 326 if (rrs->rrs_source == rsource) { 327 LIST_REMOVE(rrs, rrs_entries); 328 break; 329 } 330 if (rrs != NULL) 331 free(rrs, M_ENTROPY); 332 #endif /* defined(RANDOM_DUMMY) */ 333 } 334 335 #if !defined(RANDOM_DUMMY) 336 /* 337 * Run through all fast sources reading entropy for the given 338 * number of rounds, which should be a multiple of the number 339 * of entropy accumulation pools in use; 2 for Yarrow and 32 340 * for Fortuna. 341 * 342 * BEWARE!!! 343 * This function runs inside the RNG thread! Don't do anything silly! 344 */ 345 void 346 random_sources_feed(void) 347 { 348 uint32_t entropy[HARVESTSIZE]; 349 struct random_sources *rrs; 350 u_int i, n, local_read_rate; 351 352 /* 353 * Step over all of live entropy sources, and feed their output 354 * to the system-wide RNG. 355 */ 356 /* XXX: FIX!! Next lines as an atomic operation? */ 357 local_read_rate = read_rate; 358 read_rate = RANDOM_ALG_READ_RATE_MINIMUM; 359 LIST_FOREACH(rrs, &source_list, rrs_entries) { 360 for (i = 0; i < random_alg_context.ra_poolcount*local_read_rate; i++) { 361 n = rrs->rrs_source->rs_read(entropy, sizeof(entropy)); 362 KASSERT((n > 0 && n <= sizeof(entropy)), ("very bad return from rs_read (= %d) in %s", n, __func__)); 363 random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source); 364 } 365 } 366 explicit_bzero(entropy, sizeof(entropy)); 367 } 368 369 static int 370 random_source_handler(SYSCTL_HANDLER_ARGS) 371 { 372 struct random_sources *rrs; 373 struct sbuf sbuf; 374 int error, count; 375 376 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 377 count = 0; 378 LIST_FOREACH(rrs, &source_list, rrs_entries) { 379 sbuf_cat(&sbuf, (count++ ? ",'" : "'")); 380 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); 381 sbuf_cat(&sbuf, "'"); 382 } 383 error = sbuf_finish(&sbuf); 384 sbuf_delete(&sbuf); 385 return (error); 386 } 387 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 388 NULL, 0, random_source_handler, "A", 389 "List of active fast entropy sources."); 390 #endif /* !defined(RANDOM_DUMMY) */ 391 392 /* ARGSUSED */ 393 static int 394 randomdev_modevent(module_t mod __unused, int type, void *data __unused) 395 { 396 int error = 0; 397 398 switch (type) { 399 case MOD_LOAD: 400 printf("random: entropy device external interface\n"); 401 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 402 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random"); 403 make_dev_alias(random_dev, "urandom"); /* compatibility */ 404 break; 405 case MOD_UNLOAD: 406 destroy_dev(random_dev); 407 break; 408 case MOD_SHUTDOWN: 409 break; 410 default: 411 error = EOPNOTSUPP; 412 break; 413 } 414 return (error); 415 } 416 417 static moduledata_t randomdev_mod = { 418 "random_device", 419 randomdev_modevent, 420 0 421 }; 422 423 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); 424 MODULE_VERSION(random_device, 1); 425