1/*- 2 * Copyright (c) 2000-2015 Mark R V Murray 3 * Copyright (c) 2013 Arthur Mesh 4 * Copyright (c) 2004 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer 12 * in this position and unchanged. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 */ 29 30#include <sys/cdefs.h> 31__FBSDID("$FreeBSD: stable/11/sys/dev/random/random_harvestq.c 346725 2019-04-26 01:58:36Z mw $"); 32 33#include <sys/param.h> 34#include <sys/systm.h> 35#include <sys/conf.h> 36#include <sys/eventhandler.h> 37#include <sys/hash.h> 38#include <sys/kernel.h> 39#include <sys/kthread.h> 40#include <sys/linker.h> 41#include <sys/lock.h> 42#include <sys/malloc.h> 43#include <sys/module.h> 44#include <sys/mutex.h> 45#include <sys/random.h> 46#include <sys/sbuf.h> 47#include <sys/sysctl.h> 48#include <sys/unistd.h> 49 50#if defined(RANDOM_LOADABLE) 51#include <sys/lock.h> 52#include <sys/sx.h> 53#endif 54 55#include <machine/atomic.h> 56#include <machine/cpu.h> 57 58#include <crypto/rijndael/rijndael-api-fst.h> 59#include <crypto/sha2/sha256.h> 60 61#include <dev/random/hash.h> 62#include <dev/random/randomdev.h> 63#include <dev/random/random_harvestq.h> 64 65static void random_kthread(void); 66static void random_sources_feed(void); 67 68static u_int read_rate; 69 70/* List for the dynamic sysctls */ 71static struct sysctl_ctx_list random_clist; 72 73/* 74 * How many events to queue up. We create this many items in 75 * an 'empty' queue, then transfer them to the 'harvest' queue with 76 * supplied junk. When used, they are transferred back to the 77 * 'empty' queue. 78 */ 79#define RANDOM_RING_MAX 1024 80#define RANDOM_ACCUM_MAX 8 81 82/* 1 to let the kernel thread run, 0 to terminate, -1 to mark completion */ 83volatile int random_kthread_control; 84 85/* 86 * Put all the harvest queue context stuff in one place. 87 * this make is a bit easier to lock and protect. 88 */ 89static struct harvest_context { 90 /* The harvest mutex protects all of harvest_context and 91 * the related data. 92 */ 93 struct mtx hc_mtx; 94 /* Round-robin destination cache. */ 95 u_int hc_destination[ENTROPYSOURCE]; 96 /* The context of the kernel thread processing harvested entropy */ 97 struct proc *hc_kthread_proc; 98 /* Allow the sysadmin to select the broad category of 99 * entropy types to harvest. 100 */ 101 u_int hc_source_mask; 102 /* 103 * Lockless ring buffer holding entropy events 104 * If ring.in == ring.out, 105 * the buffer is empty. 106 * If ring.in != ring.out, 107 * the buffer contains harvested entropy. 108 * If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX), 109 * the buffer is full. 110 * 111 * NOTE: ring.in points to the last added element, 112 * and ring.out points to the last consumed element. 113 * 114 * The ring.in variable needs locking as there are multiple 115 * sources to the ring. Only the sources may change ring.in, 116 * but the consumer may examine it. 117 * 118 * The ring.out variable does not need locking as there is 119 * only one consumer. Only the consumer may change ring.out, 120 * but the sources may examine it. 121 */ 122 struct entropy_ring { 123 struct harvest_event ring[RANDOM_RING_MAX]; 124 volatile u_int in; 125 volatile u_int out; 126 } hc_entropy_ring; 127 struct fast_entropy_accumulator { 128 volatile u_int pos; 129 uint32_t buf[RANDOM_ACCUM_MAX]; 130 } hc_entropy_fast_accumulator; 131} harvest_context; 132 133static struct kproc_desc random_proc_kp = { 134 "rand_harvestq", 135 random_kthread, 136 &harvest_context.hc_kthread_proc, 137}; 138 139/* Pass the given event straight through to Fortuna/Yarrow/Whatever. */ 140static __inline void 141random_harvestq_fast_process_event(struct harvest_event *event) 142{ 143#if defined(RANDOM_LOADABLE) 144 RANDOM_CONFIG_S_LOCK(); 145 if (p_random_alg_context) 146#endif 147 p_random_alg_context->ra_event_processor(event); 148#if defined(RANDOM_LOADABLE) 149 RANDOM_CONFIG_S_UNLOCK(); 150#endif 151} 152 153static void 154random_kthread(void) 155{ 156 u_int maxloop, ring_out, i; 157 158 /* 159 * Locking is not needed as this is the only place we modify ring.out, and 160 * we only examine ring.in without changing it. Both of these are volatile, 161 * and this is a unique thread. 162 */ 163 for (random_kthread_control = 1; random_kthread_control;) { 164 /* Deal with events, if any. Restrict the number we do in one go. */ 165 maxloop = RANDOM_RING_MAX; 166 while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) { 167 ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX; 168 random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out); 169 harvest_context.hc_entropy_ring.out = ring_out; 170 if (!--maxloop) 171 break; 172 } 173 random_sources_feed(); 174 /* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */ 175 for (i = 0; i < RANDOM_ACCUM_MAX; i++) { 176 if (harvest_context.hc_entropy_fast_accumulator.buf[i]) { 177 random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), 4, RANDOM_UMA); 178 harvest_context.hc_entropy_fast_accumulator.buf[i] = 0; 179 } 180 } 181 /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */ 182 tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1)); 183 } 184 random_kthread_control = -1; 185 wakeup(&harvest_context.hc_kthread_proc); 186 kproc_exit(0); 187 /* NOTREACHED */ 188} 189/* This happens well after SI_SUB_RANDOM */ 190SYSINIT(random_device_h_proc, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, kproc_start, 191 &random_proc_kp); 192 193/* 194 * Run through all fast sources reading entropy for the given 195 * number of rounds, which should be a multiple of the number 196 * of entropy accumulation pools in use; 2 for Yarrow and 32 197 * for Fortuna. 198 */ 199static void 200random_sources_feed(void) 201{ 202 uint32_t entropy[HARVESTSIZE]; 203 struct random_sources *rrs; 204 u_int i, n, local_read_rate; 205 206 /* 207 * Step over all of live entropy sources, and feed their output 208 * to the system-wide RNG. 209 */ 210#if defined(RANDOM_LOADABLE) 211 RANDOM_CONFIG_S_LOCK(); 212 if (p_random_alg_context) { 213 /* It's an indenting error. Yeah, Yeah. */ 214#endif 215 local_read_rate = atomic_readandclear_32(&read_rate); 216 /* Perform at least one read per round */ 217 local_read_rate = MAX(local_read_rate, 1); 218 /* But not exceeding RANDOM_KEYSIZE_WORDS */ 219 local_read_rate = MIN(local_read_rate, RANDOM_KEYSIZE_WORDS); 220 LIST_FOREACH(rrs, &source_list, rrs_entries) { 221 for (i = 0; i < p_random_alg_context->ra_poolcount*local_read_rate; i++) { 222 n = rrs->rrs_source->rs_read(entropy, sizeof(entropy)); 223 KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned too much data (%u > %zu)", __func__, n, sizeof(entropy))); 224 /* It would appear that in some circumstances (e.g. virtualisation), 225 * the underlying hardware entropy source might not always return 226 * random numbers. Accept this but make a noise. If too much happens, 227 * can that source be trusted? 228 */ 229 if (n == 0) { 230 printf("%s: rs_read for hardware device '%s' returned no entropy.\n", __func__, rrs->rrs_source->rs_ident); 231 continue; 232 } 233 random_harvest_direct(entropy, n, (n*8)/2, rrs->rrs_source->rs_source); 234 } 235 } 236 explicit_bzero(entropy, sizeof(entropy)); 237#if defined(RANDOM_LOADABLE) 238 } 239 RANDOM_CONFIG_S_UNLOCK(); 240#endif 241} 242 243void 244read_rate_increment(u_int chunk) 245{ 246 247 atomic_add_32(&read_rate, chunk); 248} 249 250/* ARGSUSED */ 251RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_MASK); 252 253/* ARGSUSED */ 254static int 255random_print_harvestmask(SYSCTL_HANDLER_ARGS) 256{ 257 struct sbuf sbuf; 258 int error, i; 259 260 error = sysctl_wire_old_buffer(req, 0); 261 if (error == 0) { 262 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 263 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) 264 sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0"); 265 error = sbuf_finish(&sbuf); 266 sbuf_delete(&sbuf); 267 } 268 return (error); 269} 270 271static const char *(random_source_descr[]) = { 272 "CACHED", 273 "ATTACH", 274 "KEYBOARD", 275 "MOUSE", 276 "NET_TUN", 277 "NET_ETHER", 278 "NET_NG", 279 "INTERRUPT", 280 "SWI", 281 "FS_ATIME", 282 "UMA", /* ENVIRONMENTAL_END */ 283 "PURE_OCTEON", 284 "PURE_SAFE", 285 "PURE_GLXSB", 286 "PURE_UBSEC", 287 "PURE_HIFN", 288 "PURE_RDRAND", 289 "PURE_NEHEMIAH", 290 "PURE_RNDTEST", 291 [RANDOM_PURE_TPM] = "PURE_TPM", 292 /* "ENTROPYSOURCE" */ 293}; 294 295/* ARGSUSED */ 296static int 297random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS) 298{ 299 struct sbuf sbuf; 300 int error, i; 301 302 error = sysctl_wire_old_buffer(req, 0); 303 if (error == 0) { 304 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 305 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) { 306 sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ","); 307 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : ""); 308 sbuf_cat(&sbuf, random_source_descr[i]); 309 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : ""); 310 } 311 error = sbuf_finish(&sbuf); 312 sbuf_delete(&sbuf); 313 } 314 return (error); 315} 316 317/* ARGSUSED */ 318static void 319random_harvestq_init(void *unused __unused) 320{ 321 struct sysctl_oid *random_sys_o; 322 323 random_sys_o = SYSCTL_ADD_NODE(&random_clist, 324 SYSCTL_STATIC_CHILDREN(_kern_random), 325 OID_AUTO, "harvest", CTLFLAG_RW, 0, 326 "Entropy Device Parameters"); 327 harvest_context.hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK; 328 SYSCTL_ADD_PROC(&random_clist, 329 SYSCTL_CHILDREN(random_sys_o), 330 OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW, 331 &harvest_context.hc_source_mask, 0, 332 random_check_uint_harvestmask, "IU", 333 "Entropy harvesting mask"); 334 SYSCTL_ADD_PROC(&random_clist, 335 SYSCTL_CHILDREN(random_sys_o), 336 OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD, 337 NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)"); 338 SYSCTL_ADD_PROC(&random_clist, 339 SYSCTL_CHILDREN(random_sys_o), 340 OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD, 341 NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)"); 342 RANDOM_HARVEST_INIT_LOCK(); 343 harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0; 344} 345SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL); 346 347/* 348 * This is used to prime the RNG by grabbing any early random stuff 349 * known to the kernel, and inserting it directly into the hashing 350 * module, e.g. Fortuna or Yarrow. 351 */ 352/* ARGSUSED */ 353static void 354random_harvestq_prime(void *unused __unused) 355{ 356 struct harvest_event event; 357 size_t count, size, i; 358 uint8_t *keyfile, *data; 359 360 /* 361 * Get entropy that may have been preloaded by loader(8) 362 * and use it to pre-charge the entropy harvest queue. 363 */ 364 keyfile = preload_search_by_type(RANDOM_HARVESTQ_BOOT_ENTROPY_FILE); 365 if (keyfile != NULL) { 366 data = preload_fetch_addr(keyfile); 367 size = preload_fetch_size(keyfile); 368 /* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */ 369 size -= (size % sizeof(event.he_entropy)); 370 if (data != NULL && size != 0) { 371 for (i = 0; i < size; i += sizeof(event.he_entropy)) { 372 count = sizeof(event.he_entropy); 373 event.he_somecounter = (uint32_t)get_cyclecount(); 374 event.he_size = count; 375 event.he_bits = count/4; /* Underestimate the size for Yarrow */ 376 event.he_source = RANDOM_CACHED; 377 event.he_destination = harvest_context.hc_destination[0]++; 378 memcpy(event.he_entropy, data + i, sizeof(event.he_entropy)); 379 random_harvestq_fast_process_event(&event); 380 explicit_bzero(&event, sizeof(event)); 381 } 382 explicit_bzero(data, size); 383 if (bootverbose) 384 printf("random: read %zu bytes from preloaded cache\n", size); 385 } else 386 if (bootverbose) 387 printf("random: no preloaded entropy cache\n"); 388 } 389} 390SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, random_harvestq_prime, NULL); 391 392/* ARGSUSED */ 393static void 394random_harvestq_deinit(void *unused __unused) 395{ 396 397 /* Command the hash/reseed thread to end and wait for it to finish */ 398 random_kthread_control = 0; 399 while (random_kthread_control >= 0) 400 tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", hz/5); 401 sysctl_ctx_free(&random_clist); 402} 403SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_deinit, NULL); 404 405/*- 406 * Entropy harvesting queue routine. 407 * 408 * This is supposed to be fast; do not do anything slow in here! 409 * It is also illegal (and morally reprehensible) to insert any 410 * high-rate data here. "High-rate" is defined as a data source 411 * that will usually cause lots of failures of the "Lockless read" 412 * check a few lines below. This includes the "always-on" sources 413 * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources. 414 */ 415/* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle 416 * counters are built in, but on older hardware it will do a real time clock 417 * read which can be quite expensive. 418 */ 419void 420random_harvest_queue(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 421{ 422 struct harvest_event *event; 423 u_int ring_in; 424 425 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 426 if (!(harvest_context.hc_source_mask & (1 << origin))) 427 return; 428 RANDOM_HARVEST_LOCK(); 429 ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX; 430 if (ring_in != harvest_context.hc_entropy_ring.out) { 431 /* The ring is not full */ 432 event = harvest_context.hc_entropy_ring.ring + ring_in; 433 event->he_somecounter = (uint32_t)get_cyclecount(); 434 event->he_source = origin; 435 event->he_destination = harvest_context.hc_destination[origin]++; 436 event->he_bits = bits; 437 if (size <= sizeof(event->he_entropy)) { 438 event->he_size = size; 439 memcpy(event->he_entropy, entropy, size); 440 } 441 else { 442 /* Big event, so squash it */ 443 event->he_size = sizeof(event->he_entropy[0]); 444 event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event); 445 } 446 harvest_context.hc_entropy_ring.in = ring_in; 447 } 448 RANDOM_HARVEST_UNLOCK(); 449} 450 451/*- 452 * Entropy harvesting fast routine. 453 * 454 * This is supposed to be very fast; do not do anything slow in here! 455 * This is the right place for high-rate harvested data. 456 */ 457void 458random_harvest_fast(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 459{ 460 u_int pos; 461 462 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 463 /* XXX: FIX!! The above KASSERT is BS. Right now we ignore most structure and just accumulate the supplied data */ 464 if (!(harvest_context.hc_source_mask & (1 << origin))) 465 return; 466 pos = harvest_context.hc_entropy_fast_accumulator.pos; 467 harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount()); 468 harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX; 469} 470 471/*- 472 * Entropy harvesting direct routine. 473 * 474 * This is not supposed to be fast, but will only be used during 475 * (e.g.) booting when initial entropy is being gathered. 476 */ 477void 478random_harvest_direct(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 479{ 480 struct harvest_event event; 481 482 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 483 if (!(harvest_context.hc_source_mask & (1 << origin))) 484 return; 485 size = MIN(size, sizeof(event.he_entropy)); 486 event.he_somecounter = (uint32_t)get_cyclecount(); 487 event.he_size = size; 488 event.he_bits = bits; 489 event.he_source = origin; 490 event.he_destination = harvest_context.hc_destination[origin]++; 491 memcpy(event.he_entropy, entropy, size); 492 random_harvestq_fast_process_event(&event); 493 explicit_bzero(&event, sizeof(event)); 494} 495 496MODULE_VERSION(random_harvestq, 1); 497