1 /*- 2 * Copyright (c) 2017 Oliver Pinter 3 * Copyright (c) 2000-2015 Mark R V Murray 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/bus.h> 35 #include <sys/conf.h> 36 #include <sys/fcntl.h> 37 #include <sys/filio.h> 38 #include <sys/kernel.h> 39 #include <sys/kthread.h> 40 #include <sys/lock.h> 41 #include <sys/module.h> 42 #include <sys/malloc.h> 43 #include <sys/poll.h> 44 #include <sys/proc.h> 45 #include <sys/random.h> 46 #include <sys/sbuf.h> 47 #include <sys/selinfo.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 #include <sys/uio.h> 51 #include <sys/unistd.h> 52 53 #include <crypto/rijndael/rijndael-api-fst.h> 54 #include <crypto/sha2/sha256.h> 55 56 #include <dev/random/hash.h> 57 #include <dev/random/randomdev.h> 58 #include <dev/random/random_harvestq.h> 59 60 #define RANDOM_UNIT 0 61 62 #if defined(RANDOM_LOADABLE) 63 #define READ_RANDOM_UIO _read_random_uio 64 #define READ_RANDOM _read_random 65 static int READ_RANDOM_UIO(struct uio *, bool); 66 static u_int READ_RANDOM(void *, u_int); 67 #else 68 #define READ_RANDOM_UIO read_random_uio 69 #define READ_RANDOM read_random 70 #endif 71 72 static d_read_t randomdev_read; 73 static d_write_t randomdev_write; 74 static d_poll_t randomdev_poll; 75 static d_ioctl_t randomdev_ioctl; 76 77 static struct cdevsw random_cdevsw = { 78 .d_name = "random", 79 .d_version = D_VERSION, 80 .d_read = randomdev_read, 81 .d_write = randomdev_write, 82 .d_poll = randomdev_poll, 83 .d_ioctl = randomdev_ioctl, 84 }; 85 86 /* For use with make_dev(9)/destroy_dev(9). */ 87 static struct cdev *random_dev; 88 89 static void 90 random_alg_context_ra_init_alg(void *data) 91 { 92 93 p_random_alg_context = &random_alg_context; 94 p_random_alg_context->ra_init_alg(data); 95 #if defined(RANDOM_LOADABLE) 96 random_infra_init(READ_RANDOM_UIO, READ_RANDOM); 97 #endif 98 } 99 100 static void 101 random_alg_context_ra_deinit_alg(void *data) 102 { 103 104 #if defined(RANDOM_LOADABLE) 105 random_infra_uninit(); 106 #endif 107 p_random_alg_context->ra_deinit_alg(data); 108 p_random_alg_context = NULL; 109 } 110 111 SYSINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_init_alg, NULL); 112 SYSUNINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_deinit_alg, NULL); 113 114 static struct selinfo rsel; 115 116 /* 117 * This is the read uio(9) interface for random(4). 118 */ 119 /* ARGSUSED */ 120 static int 121 randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags) 122 { 123 124 return (READ_RANDOM_UIO(uio, (flags & O_NONBLOCK) != 0)); 125 } 126 127 int 128 READ_RANDOM_UIO(struct uio *uio, bool nonblock) 129 { 130 uint8_t *random_buf; 131 int error, spamcount; 132 ssize_t read_len, total_read, c; 133 /* 16 MiB takes about 0.08 s CPU time on my 2017 AMD Zen CPU */ 134 #define SIGCHK_PERIOD (16 * 1024 * 1024) 135 const size_t sigchk_period = SIGCHK_PERIOD; 136 137 CTASSERT(SIGCHK_PERIOD % PAGE_SIZE == 0); 138 #undef SIGCHK_PERIOD 139 140 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 141 p_random_alg_context->ra_pre_read(); 142 error = 0; 143 spamcount = 0; 144 /* (Un)Blocking logic */ 145 while (!p_random_alg_context->ra_seeded()) { 146 if (nonblock) { 147 error = EWOULDBLOCK; 148 break; 149 } 150 /* keep tapping away at the pre-read until we seed/unblock. */ 151 p_random_alg_context->ra_pre_read(); 152 /* Only bother the console every 10 seconds or so */ 153 if (spamcount == 0) 154 printf("random: %s unblock wait\n", __func__); 155 spamcount = (spamcount + 1)%100; 156 error = tsleep(&random_alg_context, PCATCH, "randseed", hz/10); 157 if (error == ERESTART || error == EINTR) 158 break; 159 } 160 if (error == 0) { 161 read_rate_increment((uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t)); 162 total_read = 0; 163 while (uio->uio_resid && !error) { 164 read_len = uio->uio_resid; 165 /* 166 * Belt-and-braces. 167 * Round up the read length to a crypto block size multiple, 168 * which is what the underlying generator is expecting. 169 * See the random_buf size requirements in the Fortuna code. 170 */ 171 read_len = roundup(read_len, RANDOM_BLOCKSIZE); 172 /* Work in chunks page-sized or less */ 173 read_len = MIN(read_len, PAGE_SIZE); 174 p_random_alg_context->ra_read(random_buf, read_len); 175 c = MIN(uio->uio_resid, read_len); 176 /* 177 * uiomove() may yield the CPU before each 'c' bytes 178 * (up to PAGE_SIZE) are copied out. 179 */ 180 error = uiomove(random_buf, c, uio); 181 total_read += c; 182 /* 183 * Poll for signals every few MBs to avoid very long 184 * uninterruptible syscalls. 185 */ 186 if (error == 0 && uio->uio_resid != 0 && 187 total_read % sigchk_period == 0) 188 error = tsleep_sbt(&random_alg_context, PCATCH, 189 "randrd", SBT_1NS, 0, C_HARDCLOCK); 190 } 191 if (error == ERESTART || error == EINTR) 192 error = 0; 193 } 194 free(random_buf, M_ENTROPY); 195 return (error); 196 } 197 198 /*- 199 * Kernel API version of read_random(). 200 * This is similar to random_alg_read(), 201 * except it doesn't interface with uio(9). 202 * It cannot assumed that random_buf is a multiple of 203 * RANDOM_BLOCKSIZE bytes. 204 */ 205 u_int 206 READ_RANDOM(void *random_buf, u_int len) 207 { 208 u_int read_len; 209 uint8_t local_buf[len + RANDOM_BLOCKSIZE]; 210 211 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); 212 p_random_alg_context->ra_pre_read(); 213 /* (Un)Blocking logic; if not seeded, return nothing. */ 214 if (p_random_alg_context->ra_seeded()) { 215 read_rate_increment((len + sizeof(uint32_t))/sizeof(uint32_t)); 216 if (len > 0) { 217 /* 218 * Belt-and-braces. 219 * Round up the read length to a crypto block size multiple, 220 * which is what the underlying generator is expecting. 221 */ 222 read_len = roundup(len, RANDOM_BLOCKSIZE); 223 p_random_alg_context->ra_read(local_buf, read_len); 224 memcpy(random_buf, local_buf, len); 225 } 226 } else 227 len = 0; 228 return (len); 229 } 230 231 static __inline void 232 randomdev_accumulate(uint8_t *buf, u_int count) 233 { 234 static u_int destination = 0; 235 static struct harvest_event event; 236 static struct randomdev_hash hash; 237 static uint32_t entropy_data[RANDOM_KEYSIZE_WORDS]; 238 uint32_t timestamp; 239 int i; 240 241 /* Extra timing here is helpful to scrape scheduler jitter entropy */ 242 randomdev_hash_init(&hash); 243 timestamp = (uint32_t)get_cyclecount(); 244 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 245 randomdev_hash_iterate(&hash, buf, count); 246 timestamp = (uint32_t)get_cyclecount(); 247 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 248 randomdev_hash_finish(&hash, entropy_data); 249 explicit_bzero(&hash, sizeof(hash)); 250 for (i = 0; i < RANDOM_KEYSIZE_WORDS; i += sizeof(event.he_entropy)/sizeof(event.he_entropy[0])) { 251 event.he_somecounter = (uint32_t)get_cyclecount(); 252 event.he_size = sizeof(event.he_entropy); 253 event.he_source = RANDOM_CACHED; 254 event.he_destination = destination++; /* Harmless cheating */ 255 memcpy(event.he_entropy, entropy_data + i, sizeof(event.he_entropy)); 256 p_random_alg_context->ra_event_processor(&event); 257 } 258 explicit_bzero(entropy_data, sizeof(entropy_data)); 259 } 260 261 /* ARGSUSED */ 262 static int 263 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 264 { 265 uint8_t *random_buf; 266 int c, error = 0; 267 ssize_t nbytes; 268 269 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 270 nbytes = uio->uio_resid; 271 while (uio->uio_resid > 0 && error == 0) { 272 c = MIN(uio->uio_resid, PAGE_SIZE); 273 error = uiomove(random_buf, c, uio); 274 if (error) 275 break; 276 randomdev_accumulate(random_buf, c); 277 tsleep(&random_alg_context, 0, "randwr", hz/10); 278 } 279 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR)) 280 /* Partial write, not error. */ 281 error = 0; 282 free(random_buf, M_ENTROPY); 283 return (error); 284 } 285 286 /* ARGSUSED */ 287 static int 288 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused) 289 { 290 291 if (events & (POLLIN | POLLRDNORM)) { 292 if (p_random_alg_context->ra_seeded()) 293 events &= (POLLIN | POLLRDNORM); 294 else 295 selrecord(td, &rsel); 296 } 297 return (events); 298 } 299 300 /* This will be called by the entropy processor when it seeds itself and becomes secure */ 301 void 302 randomdev_unblock(void) 303 { 304 305 selwakeuppri(&rsel, PUSER); 306 wakeup(&random_alg_context); 307 printf("random: unblocking device.\n"); 308 /* Do random(9) a favour while we are about it. */ 309 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE); 310 } 311 312 /* ARGSUSED */ 313 static int 314 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 315 int flags __unused, struct thread *td __unused) 316 { 317 int error = 0; 318 319 switch (cmd) { 320 /* Really handled in upper layer */ 321 case FIOASYNC: 322 case FIONBIO: 323 break; 324 default: 325 error = ENOTTY; 326 } 327 328 return (error); 329 } 330 331 void 332 random_source_register(struct random_source *rsource) 333 { 334 struct random_sources *rrs; 335 336 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 337 338 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); 339 rrs->rrs_source = rsource; 340 341 random_harvest_register_source(rsource->rs_source); 342 343 printf("random: registering fast source %s\n", rsource->rs_ident); 344 LIST_INSERT_HEAD(&source_list, rrs, rrs_entries); 345 } 346 347 void 348 random_source_deregister(struct random_source *rsource) 349 { 350 struct random_sources *rrs = NULL; 351 352 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 353 354 random_harvest_deregister_source(rsource->rs_source); 355 356 LIST_FOREACH(rrs, &source_list, rrs_entries) 357 if (rrs->rrs_source == rsource) { 358 LIST_REMOVE(rrs, rrs_entries); 359 break; 360 } 361 if (rrs != NULL) 362 free(rrs, M_ENTROPY); 363 } 364 365 static int 366 random_source_handler(SYSCTL_HANDLER_ARGS) 367 { 368 struct random_sources *rrs; 369 struct sbuf sbuf; 370 int error, count; 371 372 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 373 count = 0; 374 LIST_FOREACH(rrs, &source_list, rrs_entries) { 375 sbuf_cat(&sbuf, (count++ ? ",'" : "'")); 376 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); 377 sbuf_cat(&sbuf, "'"); 378 } 379 error = sbuf_finish(&sbuf); 380 sbuf_delete(&sbuf); 381 return (error); 382 } 383 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 384 NULL, 0, random_source_handler, "A", 385 "List of active fast entropy sources."); 386 387 /* ARGSUSED */ 388 static int 389 randomdev_modevent(module_t mod __unused, int type, void *data __unused) 390 { 391 int error = 0; 392 393 switch (type) { 394 case MOD_LOAD: 395 printf("random: entropy device external interface\n"); 396 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 397 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random"); 398 make_dev_alias(random_dev, "urandom"); /* compatibility */ 399 break; 400 case MOD_UNLOAD: 401 destroy_dev(random_dev); 402 break; 403 case MOD_SHUTDOWN: 404 break; 405 default: 406 error = EOPNOTSUPP; 407 break; 408 } 409 return (error); 410 } 411 412 static moduledata_t randomdev_mod = { 413 "random_device", 414 randomdev_modevent, 415 0 416 }; 417 418 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); 419 MODULE_VERSION(random_device, 1); 420 MODULE_DEPEND(random_device, crypto, 1, 1, 1); 421 MODULE_DEPEND(random_device, random_harvestq, 1, 1, 1); 422