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; 133 134 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 135 p_random_alg_context->ra_pre_read(); 136 error = 0; 137 spamcount = 0; 138 /* (Un)Blocking logic */ 139 while (!p_random_alg_context->ra_seeded()) { 140 if (nonblock) { 141 error = EWOULDBLOCK; 142 break; 143 } 144 /* keep tapping away at the pre-read until we seed/unblock. */ 145 p_random_alg_context->ra_pre_read(); 146 /* Only bother the console every 10 seconds or so */ 147 if (spamcount == 0) 148 printf("random: %s unblock wait\n", __func__); 149 spamcount = (spamcount + 1)%100; 150 error = tsleep(&random_alg_context, PCATCH, "randseed", hz/10); 151 if (error == ERESTART || error == EINTR) 152 break; 153 } 154 if (error == 0) { 155 read_rate_increment((uio->uio_resid + sizeof(uint32_t))/sizeof(uint32_t)); 156 total_read = 0; 157 while (uio->uio_resid && !error) { 158 read_len = uio->uio_resid; 159 /* 160 * Belt-and-braces. 161 * Round up the read length to a crypto block size multiple, 162 * which is what the underlying generator is expecting. 163 * See the random_buf size requirements in the Yarrow/Fortuna code. 164 */ 165 read_len = roundup(read_len, RANDOM_BLOCKSIZE); 166 /* Work in chunks page-sized or less */ 167 read_len = MIN(read_len, PAGE_SIZE); 168 p_random_alg_context->ra_read(random_buf, read_len); 169 c = MIN(uio->uio_resid, read_len); 170 error = uiomove(random_buf, c, uio); 171 total_read += c; 172 } 173 if (total_read != uio->uio_resid && (error == ERESTART || error == EINTR)) 174 /* Return partial read, not error. */ 175 error = 0; 176 } 177 free(random_buf, M_ENTROPY); 178 return (error); 179 } 180 181 /*- 182 * Kernel API version of read_random(). 183 * This is similar to random_alg_read(), 184 * except it doesn't interface with uio(9). 185 * It cannot assumed that random_buf is a multiple of 186 * RANDOM_BLOCKSIZE bytes. 187 */ 188 u_int 189 READ_RANDOM(void *random_buf, u_int len) 190 { 191 u_int read_len; 192 uint8_t local_buf[len + RANDOM_BLOCKSIZE]; 193 194 KASSERT(random_buf != NULL, ("No suitable random buffer in %s", __func__)); 195 p_random_alg_context->ra_pre_read(); 196 /* (Un)Blocking logic; if not seeded, return nothing. */ 197 if (p_random_alg_context->ra_seeded()) { 198 read_rate_increment((len + sizeof(uint32_t))/sizeof(uint32_t)); 199 if (len > 0) { 200 /* 201 * Belt-and-braces. 202 * Round up the read length to a crypto block size multiple, 203 * which is what the underlying generator is expecting. 204 */ 205 read_len = roundup(len, RANDOM_BLOCKSIZE); 206 p_random_alg_context->ra_read(local_buf, read_len); 207 memcpy(random_buf, local_buf, len); 208 } 209 } else 210 len = 0; 211 return (len); 212 } 213 214 static __inline void 215 randomdev_accumulate(uint8_t *buf, u_int count) 216 { 217 static u_int destination = 0; 218 static struct harvest_event event; 219 static struct randomdev_hash hash; 220 static uint32_t entropy_data[RANDOM_KEYSIZE_WORDS]; 221 uint32_t timestamp; 222 int i; 223 224 /* Extra timing here is helpful to scrape scheduler jitter entropy */ 225 randomdev_hash_init(&hash); 226 timestamp = (uint32_t)get_cyclecount(); 227 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 228 randomdev_hash_iterate(&hash, buf, count); 229 timestamp = (uint32_t)get_cyclecount(); 230 randomdev_hash_iterate(&hash, ×tamp, sizeof(timestamp)); 231 randomdev_hash_finish(&hash, entropy_data); 232 explicit_bzero(&hash, sizeof(hash)); 233 for (i = 0; i < RANDOM_KEYSIZE_WORDS; i += sizeof(event.he_entropy)/sizeof(event.he_entropy[0])) { 234 event.he_somecounter = (uint32_t)get_cyclecount(); 235 event.he_size = sizeof(event.he_entropy); 236 event.he_bits = event.he_size/8; 237 event.he_source = RANDOM_CACHED; 238 event.he_destination = destination++; /* Harmless cheating */ 239 memcpy(event.he_entropy, entropy_data + i, sizeof(event.he_entropy)); 240 p_random_alg_context->ra_event_processor(&event); 241 } 242 explicit_bzero(entropy_data, sizeof(entropy_data)); 243 } 244 245 /* ARGSUSED */ 246 static int 247 randomdev_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 248 { 249 uint8_t *random_buf; 250 int c, error = 0; 251 ssize_t nbytes; 252 253 random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK); 254 nbytes = uio->uio_resid; 255 while (uio->uio_resid > 0 && error == 0) { 256 c = MIN(uio->uio_resid, PAGE_SIZE); 257 error = uiomove(random_buf, c, uio); 258 if (error) 259 break; 260 randomdev_accumulate(random_buf, c); 261 tsleep(&random_alg_context, 0, "randwr", hz/10); 262 } 263 if (nbytes != uio->uio_resid && (error == ERESTART || error == EINTR)) 264 /* Partial write, not error. */ 265 error = 0; 266 free(random_buf, M_ENTROPY); 267 return (error); 268 } 269 270 /* ARGSUSED */ 271 static int 272 randomdev_poll(struct cdev *dev __unused, int events, struct thread *td __unused) 273 { 274 275 if (events & (POLLIN | POLLRDNORM)) { 276 if (p_random_alg_context->ra_seeded()) 277 events &= (POLLIN | POLLRDNORM); 278 else 279 selrecord(td, &rsel); 280 } 281 return (events); 282 } 283 284 /* This will be called by the entropy processor when it seeds itself and becomes secure */ 285 void 286 randomdev_unblock(void) 287 { 288 289 selwakeuppri(&rsel, PUSER); 290 wakeup(&random_alg_context); 291 printf("random: unblocking device.\n"); 292 /* Do random(9) a favour while we are about it. */ 293 (void)atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_NONE, ARC4_ENTR_HAVE); 294 } 295 296 /* ARGSUSED */ 297 static int 298 randomdev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused, 299 int flags __unused, struct thread *td __unused) 300 { 301 int error = 0; 302 303 switch (cmd) { 304 /* Really handled in upper layer */ 305 case FIOASYNC: 306 case FIONBIO: 307 break; 308 default: 309 error = ENOTTY; 310 } 311 312 return (error); 313 } 314 315 void 316 random_source_register(struct random_source *rsource) 317 { 318 struct random_sources *rrs; 319 320 KASSERT(rsource != NULL, ("invalid input to %s", __func__)); 321 322 rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); 323 rrs->rrs_source = rsource; 324 325 random_harvest_register_source(rsource->rs_source); 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__)); 337 338 random_harvest_deregister_source(rsource->rs_source); 339 340 LIST_FOREACH(rrs, &source_list, rrs_entries) 341 if (rrs->rrs_source == rsource) { 342 LIST_REMOVE(rrs, rrs_entries); 343 break; 344 } 345 if (rrs != NULL) 346 free(rrs, M_ENTROPY); 347 } 348 349 static int 350 random_source_handler(SYSCTL_HANDLER_ARGS) 351 { 352 struct random_sources *rrs; 353 struct sbuf sbuf; 354 int error, count; 355 356 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 357 count = 0; 358 LIST_FOREACH(rrs, &source_list, rrs_entries) { 359 sbuf_cat(&sbuf, (count++ ? ",'" : "'")); 360 sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); 361 sbuf_cat(&sbuf, "'"); 362 } 363 error = sbuf_finish(&sbuf); 364 sbuf_delete(&sbuf); 365 return (error); 366 } 367 SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 368 NULL, 0, random_source_handler, "A", 369 "List of active fast entropy sources."); 370 371 /* ARGSUSED */ 372 static int 373 randomdev_modevent(module_t mod __unused, int type, void *data __unused) 374 { 375 int error = 0; 376 377 switch (type) { 378 case MOD_LOAD: 379 printf("random: entropy device external interface\n"); 380 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw, 381 RANDOM_UNIT, NULL, UID_ROOT, GID_WHEEL, 0644, "random"); 382 make_dev_alias(random_dev, "urandom"); /* compatibility */ 383 break; 384 case MOD_UNLOAD: 385 destroy_dev(random_dev); 386 break; 387 case MOD_SHUTDOWN: 388 break; 389 default: 390 error = EOPNOTSUPP; 391 break; 392 } 393 return (error); 394 } 395 396 static moduledata_t randomdev_mod = { 397 "random_device", 398 randomdev_modevent, 399 0 400 }; 401 402 DECLARE_MODULE(random_device, randomdev_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); 403 MODULE_VERSION(random_device, 1); 404 MODULE_DEPEND(random_device, crypto, 1, 1, 1); 405 MODULE_DEPEND(random_device, random_harvestq, 1, 1, 1); 406