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/sha256.h> 54 55 #include <dev/random/hash.h> 56 #include <dev/random/randomdev.h> 57 #include <dev/random/random_harvestq.h> 58 59 #define RANDOM_UNIT 0 60 61 #if defined(RANDOM_LOADABLE) 62 #define READ_RANDOM_UIO _read_random_uio 63 #define READ_RANDOM _read_random 64 static int READ_RANDOM_UIO(struct uio *, bool); 65 static u_int READ_RANDOM(void *, u_int); 66 #else 67 #define READ_RANDOM_UIO read_random_uio 68 #define READ_RANDOM read_random 69 #endif 70 71 /* Return the largest number >= x that is a multiple of m */ 72 #define CEIL_TO_MULTIPLE(x, m) ((((x) + (m) - 1)/(m))*(m)) 73 74 static d_read_t randomdev_read; 75 static d_write_t randomdev_write; 76 static d_poll_t randomdev_poll; 77 static d_ioctl_t randomdev_ioctl; 78 79 static struct cdevsw random_cdevsw = { 80 .d_name = "random", 81 .d_version = D_VERSION, 82 .d_read = randomdev_read, 83 .d_write = randomdev_write, 84 .d_poll = randomdev_poll, 85 .d_ioctl = randomdev_ioctl, 86 }; 87 88 /* For use with make_dev(9)/destroy_dev(9). */ 89 static struct cdev *random_dev; 90 91 static void 92 random_alg_context_ra_init_alg(void *data) 93 { 94 95 p_random_alg_context = &random_alg_context; 96 p_random_alg_context->ra_init_alg(data); 97 #if defined(RANDOM_LOADABLE) 98 random_infra_init(READ_RANDOM_UIO, READ_RANDOM); 99 #endif 100 } 101 102 static void 103 random_alg_context_ra_deinit_alg(void *data) 104 { 105 106 #if defined(RANDOM_LOADABLE) 107 random_infra_uninit(); 108 #endif 109 p_random_alg_context->ra_deinit_alg(data); 110 p_random_alg_context = NULL; 111 } 112 113 SYSINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_init_alg, NULL); 114 SYSUNINIT(random_device, SI_SUB_RANDOM, SI_ORDER_THIRD, random_alg_context_ra_deinit_alg, NULL); 115 116 static struct selinfo rsel; 117 118 /* 119 * This is the read uio(9) interface for random(4). 120 */ 121 /* ARGSUSED */ 122 static int 123 randomdev_read(struct cdev *dev __unused, struct uio *uio, int flags) 124 { 125 126 return (READ_RANDOM_UIO(uio, (flags & O_NONBLOCK) != 0)); 127 } 128 129 int 130 READ_RANDOM_UIO(struct uio *uio, bool nonblock) 131 { 132 uint8_t *random_buf; 133 int error, spamcount; 134 ssize_t read_len, total_read, c; 135 136 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 137 p_random_alg_context->ra_pre_read(); 138 error = 0; 139 spamcount = 0; 140 /* (Un)Blocking logic */ 141 while (!p_random_alg_context->ra_seeded()) { 142 if (nonblock) { 143 error = EWOULDBLOCK; 144 break; 145 } 146 /* keep tapping away at the pre-read until we seed/unblock. */ 147 p_random_alg_context->ra_pre_read(); 148 /* Only bother the console every 10 seconds or so */ 149 if (spamcount == 0) 150 printf("random: %s unblock wait\n", __func__); 151 spamcount = (spamcount + 1)%100; 152 error = tsleep(&random_alg_context, PCATCH, "randseed", hz/10); 153 if (error == ERESTART || error == EINTR) 154 break; 155 } 156 if (error == 0) { 157 read_rate_increment((uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t)); 158 total_read = 0; 159 while (uio->uio_resid && !error) { 160 read_len = uio->uio_resid; 161 /* 162 * Belt-and-braces. 163 * Round up the read length to a crypto block size multiple, 164 * which is what the underlying generator is expecting. 165 * See the random_buf size requirements in the Yarrow/Fortuna code. 166 */ 167 read_len = CEIL_TO_MULTIPLE(read_len, RANDOM_BLOCKSIZE); 168 /* Work in chunks page-sized or less */ 169 read_len = MIN(read_len, PAGE_SIZE); 170 p_random_alg_context->ra_read(random_buf, read_len); 171 c = MIN(uio->uio_resid, read_len); 172 error = uiomove(random_buf, c, uio); 173 total_read += c; 174 } 175 if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR)) 176 /* Return partial read, not error. */ 177 error = 0; 178 } 179 free(random_buf, M_ENTROPY); 180 return (error); 181 } 182 183 /*- 184 * Kernel API version of read_random(). 185 * This is similar to random_alg_read(), 186 * except it doesn't interface with uio(9). 187 * It cannot assumed that random_buf is a multiple of 188 * RANDOM_BLOCKSIZE bytes. 189 */ 190 u_int 191 READ_RANDOM(void *random_buf, u_int len) 192 { 193 u_int read_len; 194 uint8_t local_buf[len + RANDOM_BLOCKSIZE]; 195 196 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); 197 p_random_alg_context->ra_pre_read(); 198 /* (Un)Blocking logic; if not seeded, return nothing. */ 199 if (p_random_alg_context->ra_seeded()) { 200 read_rate_increment((len + sizeof(uint32_t))/sizeof(uint32_t)); 201 if (len > 0) { 202 /* 203 * Belt-and-braces. 204 * Round up the read length to a crypto block size multiple, 205 * which is what the underlying generator is expecting. 206 */ 207 read_len = CEIL_TO_MULTIPLE(len, RANDOM_BLOCKSIZE); 208 p_random_alg_context->ra_read(local_buf, read_len); 209 memcpy(random_buf, local_buf, len); 210 } 211 } else 212 len = 0; 213 return (len); 214 } 215 216 static __inline void 217 randomdev_accumulate(uint8_t *buf, u_int count) 218 { 219 static u_int destination = 0; 220 static struct harvest_event event; 221 static struct randomdev_hash hash; 222 static uint32_t entropy_data[RANDOM_KEYSIZE_WORDS]; 223 uint32_t timestamp; 224 int i; 225 226 /* Extra timing here is helpful to scrape scheduler jitter entropy */ 227 randomdev_hash_init(&hash); 228 timestamp = (uint32_t)get_cyclecount(); 229 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 230 randomdev_hash_iterate(&hash, buf, count); 231 timestamp = (uint32_t)get_cyclecount(); 232 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 233 randomdev_hash_finish(&hash, entropy_data); 234 explicit_bzero(&hash, sizeof(hash)); 235 for (i = 0; i < RANDOM_KEYSIZE_WORDS; i += sizeof(event.he_entropy)/sizeof(event.he_entropy[0])) { 236 event.he_somecounter = (uint32_t)get_cyclecount(); 237 event.he_size = sizeof(event.he_entropy); 238 event.he_bits = event.he_size/8; 239 event.he_source = RANDOM_CACHED; 240 event.he_destination = destination++; /* Harmless cheating */ 241 memcpy(event.he_entropy, entropy_data + i, sizeof(event.he_entropy)); 242 p_random_alg_context->ra_event_processor(&event); 243 } 244 explicit_bzero(entropy_data, sizeof(entropy_data)); 245 } 246 247 /* ARGSUSED */ 248 static int 249 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 250 { 251 uint8_t *random_buf; 252 int c, error = 0; 253 ssize_t nbytes; 254 255 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 256 nbytes = uio->uio_resid; 257 while (uio->uio_resid > 0 && error == 0) { 258 c = MIN(uio->uio_resid, PAGE_SIZE); 259 error = uiomove(random_buf, c, uio); 260 if (error) 261 break; 262 randomdev_accumulate(random_buf, c); 263 tsleep(&random_alg_context, 0, "randwr", hz/10); 264 } 265 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR)) 266 /* Partial write, not error. */ 267 error = 0; 268 free(random_buf, M_ENTROPY); 269 return (error); 270 } 271 272 /* ARGSUSED */ 273 static int 274 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused) 275 { 276 277 if (events & (POLLIN | POLLRDNORM)) { 278 if (p_random_alg_context->ra_seeded()) 279 events &= (POLLIN | POLLRDNORM); 280 else 281 selrecord(td, &rsel); 282 } 283 return (events); 284 } 285 286 /* This will be called by the entropy processor when it seeds itself and becomes secure */ 287 void 288 randomdev_unblock(void) 289 { 290 291 selwakeuppri(&rsel, PUSER); 292 wakeup(&random_alg_context); 293 printf("random: unblocking device.\n"); 294 /* Do random(9) a favour while we are about it. */ 295 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE); 296 } 297 298 /* ARGSUSED */ 299 static int 300 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 301 int flags __unused, struct thread *td __unused) 302 { 303 int error = 0; 304 305 switch (cmd) { 306 /* Really handled in upper layer */ 307 case FIOASYNC: 308 case FIONBIO: 309 break; 310 default: 311 error = ENOTTY; 312 } 313 314 return (error); 315 } 316 317 void 318 random_source_register(struct random_source *rsource) 319 { 320 struct random_sources *rrs; 321 322 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 323 324 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); 325 rrs->rrs_source = rsource; 326 327 printf("random: registering fast source %s\n", rsource->rs_ident); 328 LIST_INSERT_HEAD(&source_list, rrs, rrs_entries); 329 } 330 331 void 332 random_source_deregister(struct random_source *rsource) 333 { 334 struct random_sources *rrs = NULL; 335 336 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 337 LIST_FOREACH(rrs, &source_list, rrs_entries) 338 if (rrs->rrs_source == rsource) { 339 LIST_REMOVE(rrs, rrs_entries); 340 break; 341 } 342 if (rrs != NULL) 343 free(rrs, M_ENTROPY); 344 } 345 346 static int 347 random_source_handler(SYSCTL_HANDLER_ARGS) 348 { 349 struct random_sources *rrs; 350 struct sbuf sbuf; 351 int error, count; 352 353 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 354 count = 0; 355 LIST_FOREACH(rrs, &source_list, rrs_entries) { 356 sbuf_cat(&sbuf, (count++ ? ",'" : "'")); 357 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); 358 sbuf_cat(&sbuf, "'"); 359 } 360 error = sbuf_finish(&sbuf); 361 sbuf_delete(&sbuf); 362 return (error); 363 } 364 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 365 NULL, 0, random_source_handler, "A", 366 "List of active fast entropy sources."); 367 368 /* ARGSUSED */ 369 static int 370 randomdev_modevent(module_t mod __unused, int type, void *data __unused) 371 { 372 int error = 0; 373 374 switch (type) { 375 case MOD_LOAD: 376 printf("random: entropy device external interface\n"); 377 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 378 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random"); 379 make_dev_alias(random_dev, "urandom"); /* compatibility */ 380 break; 381 case MOD_UNLOAD: 382 destroy_dev(random_dev); 383 break; 384 case MOD_SHUTDOWN: 385 break; 386 default: 387 error = EOPNOTSUPP; 388 break; 389 } 390 return (error); 391 } 392 393 static moduledata_t randomdev_mod = { 394 "random_device", 395 randomdev_modevent, 396 0 397 }; 398 399 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); 400 MODULE_VERSION(random_device, 1); 401 MODULE_DEPEND(random_device, crypto, 1, 1, 1); 402 MODULE_DEPEND(random_device, random_harvestq, 1, 1, 1); 403