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