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("$FreeBSD$"); 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 #include <machine/cpu.h> 51 52 #include <dev/random/randomdev.h> 53 #include <dev/random/random_harvestq.h> 54 55 static void random_kthread(void); 56 57 /* List for the dynamic sysctls */ 58 static struct sysctl_ctx_list random_clist; 59 60 /* 61 * How many events to queue up. We create this many items in 62 * an 'empty' queue, then transfer them to the 'harvest' queue with 63 * supplied junk. When used, they are transferred back to the 64 * 'empty' queue. 65 */ 66 #define RANDOM_RING_MAX 1024 67 #define RANDOM_ACCUM_MAX 8 68 69 /* 1 to let the kernel thread run, 0 to terminate */ 70 volatile int random_kthread_control; 71 72 /* 73 * Put all the harvest queue context stuff in one place. 74 * this make is a bit easier to lock and protect. 75 */ 76 static struct harvest_context { 77 /* The harvest mutex protects all of harvest_context and 78 * the related data. 79 */ 80 struct mtx hc_mtx; 81 /* Round-robin destination cache. */ 82 u_int hc_destination[ENTROPYSOURCE]; 83 /* The context of the kernel thread processing harvested entropy */ 84 struct proc *hc_kthread_proc; 85 /* Allow the sysadmin to select the broad category of 86 * entropy types to harvest. 87 */ 88 u_int hc_source_mask; 89 /* 90 * Lockless ring buffer holding entropy events 91 * If ring.in == ring.out, 92 * the buffer is empty. 93 * If ring.in != ring.out, 94 * the buffer contains harvested entropy. 95 * If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX), 96 * the buffer is full. 97 * 98 * NOTE: ring.in points to the last added element, 99 * and ring.out points to the last consumed element. 100 * 101 * The ring.in variable needs locking as there are multiple 102 * sources to the ring. Only the sources may change ring.in, 103 * but the consumer may examine it. 104 * 105 * The ring.out variable does not need locking as there is 106 * only one consumer. Only the consumer may change ring.out, 107 * but the sources may examine it. 108 */ 109 struct entropy_ring { 110 struct harvest_event ring[RANDOM_RING_MAX]; 111 volatile u_int in; 112 volatile u_int out; 113 } hc_entropy_ring; 114 struct fast_entropy_accumulator { 115 volatile u_int pos; 116 uint32_t buf[RANDOM_ACCUM_MAX]; 117 } hc_entropy_fast_accumulator; 118 } harvest_context; 119 120 static struct kproc_desc random_proc_kp = { 121 "rand_harvestq", 122 random_kthread, 123 &harvest_context.hc_kthread_proc, 124 }; 125 126 127 /* Pass the given event straight through to Fortuna/Yarrow/Whatever. */ 128 static __inline void 129 random_harvestq_fast_process_event(struct harvest_event *event) 130 { 131 if (random_alg_context.ra_event_processor) 132 random_alg_context.ra_event_processor(event); 133 } 134 135 static void 136 random_kthread(void) 137 { 138 u_int maxloop, ring_out, i; 139 140 /* 141 * Locking is not needed as this is the only place we modify ring.out, and 142 * we only examine ring.in without changing it. Both of these are volatile, 143 * and this is a unique thread. 144 */ 145 for (random_kthread_control = 1; random_kthread_control;) { 146 /* Deal with events, if any. Restrict the number we do in one go. */ 147 maxloop = RANDOM_RING_MAX; 148 while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) { 149 ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX; 150 random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out); 151 harvest_context.hc_entropy_ring.out = ring_out; 152 if (!--maxloop) 153 break; 154 } 155 random_sources_feed(); 156 /* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */ 157 for (i = 0; i < RANDOM_ACCUM_MAX; i++) { 158 if (harvest_context.hc_entropy_fast_accumulator.buf[i]) { 159 random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), 4, RANDOM_FAST); 160 harvest_context.hc_entropy_fast_accumulator.buf[i] = 0; 161 } 162 } 163 /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */ 164 tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1)); 165 } 166 wakeup(&harvest_context.hc_kthread_proc); 167 kproc_exit(0); 168 /* NOTREACHED */ 169 } 170 SYSINIT(random_device_h_proc, SI_SUB_CREATE_INIT, SI_ORDER_ANY, kproc_start, &random_proc_kp); 171 172 /* ARGSUSED */ 173 RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_MASK); 174 175 /* ARGSUSED */ 176 static int 177 random_print_harvestmask(SYSCTL_HANDLER_ARGS) 178 { 179 struct sbuf sbuf; 180 int error, i; 181 182 error = sysctl_wire_old_buffer(req, 0); 183 if (error == 0) { 184 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 185 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) 186 sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0"); 187 error = sbuf_finish(&sbuf); 188 sbuf_delete(&sbuf); 189 } 190 return (error); 191 } 192 193 static const char *(random_source_descr[]) = { 194 "CACHED", 195 "ATTACH", 196 "KEYBOARD", 197 "MOUSE", 198 "NET_TUN", 199 "NET_ETHER", 200 "NET_NG", 201 "INTERRUPT", 202 "SWI", 203 "FS_ATIME", 204 "HIGH_PERFORMANCE", /* ENVIRONMENTAL_END */ 205 "PURE_OCTEON", 206 "PURE_SAFE", 207 "PURE_GLXSB", 208 "PURE_UBSEC", 209 "PURE_HIFN", 210 "PURE_RDRAND", 211 "PURE_NEHEMIAH", 212 "PURE_RNDTEST", 213 /* "ENTROPYSOURCE" */ 214 }; 215 216 /* ARGSUSED */ 217 static int 218 random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS) 219 { 220 struct sbuf sbuf; 221 int error, i; 222 223 error = sysctl_wire_old_buffer(req, 0); 224 if (error == 0) { 225 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 226 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) { 227 sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ","); 228 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : ""); 229 sbuf_cat(&sbuf, random_source_descr[i]); 230 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : ""); 231 } 232 error = sbuf_finish(&sbuf); 233 sbuf_delete(&sbuf); 234 } 235 return (error); 236 } 237 238 /* ARGSUSED */ 239 static void 240 random_harvestq_init(void *unused __unused) 241 { 242 struct sysctl_oid *random_sys_o; 243 244 random_sys_o = SYSCTL_ADD_NODE(&random_clist, 245 SYSCTL_STATIC_CHILDREN(_kern_random), 246 OID_AUTO, "harvest", CTLFLAG_RW, 0, 247 "Entropy Device Parameters"); 248 harvest_context.hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK; 249 SYSCTL_ADD_PROC(&random_clist, 250 SYSCTL_CHILDREN(random_sys_o), 251 OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW, 252 &harvest_context.hc_source_mask, 0, 253 random_check_uint_harvestmask, "IU", 254 "Entropy harvesting mask"); 255 SYSCTL_ADD_PROC(&random_clist, 256 SYSCTL_CHILDREN(random_sys_o), 257 OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD, 258 NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)"); 259 SYSCTL_ADD_PROC(&random_clist, 260 SYSCTL_CHILDREN(random_sys_o), 261 OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD, 262 NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)"); 263 RANDOM_HARVEST_INIT_LOCK(); 264 harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0; 265 } 266 SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL); 267 268 /* 269 * This is used to prime the RNG by grabbing any early random stuff 270 * known to the kernel, and inserting it directly into the hashing 271 * module, e.g. Fortuna or Yarrow. 272 */ 273 /* ARGSUSED */ 274 static void 275 random_harvestq_prime(void *unused __unused) 276 { 277 struct harvest_event event; 278 size_t count, size, i; 279 uint8_t *keyfile, *data; 280 281 /* 282 * Get entropy that may have been preloaded by loader(8) 283 * and use it to pre-charge the entropy harvest queue. 284 */ 285 keyfile = preload_search_by_type(RANDOM_HARVESTQ_BOOT_ENTROPY_FILE); 286 if (keyfile != NULL) { 287 data = preload_fetch_addr(keyfile); 288 size = preload_fetch_size(keyfile); 289 /* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */ 290 size -= (size % sizeof(event.he_entropy)); 291 if (data != NULL && size != 0) { 292 for (i = 0; i < size; i += sizeof(event.he_entropy)) { 293 count = sizeof(event.he_entropy); 294 event.he_somecounter = (uint32_t)get_cyclecount(); 295 event.he_size = count; 296 event.he_bits = count/4; /* Underestimate the size for Yarrow */ 297 event.he_source = RANDOM_CACHED; 298 event.he_destination = harvest_context.hc_destination[0]++; 299 memcpy(event.he_entropy, data + i, sizeof(event.he_entropy)); 300 random_harvestq_fast_process_event(&event); 301 explicit_bzero(&event, sizeof(event)); 302 } 303 explicit_bzero(data, size); 304 if (bootverbose) 305 printf("random: read %zu bytes from preloaded cache\n", size); 306 } else 307 if (bootverbose) 308 printf("random: no preloaded entropy cache\n"); 309 } 310 } 311 SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, random_harvestq_prime, NULL); 312 313 /* ARGSUSED */ 314 static void 315 random_harvestq_deinit(void *unused __unused) 316 { 317 318 /* Command the hash/reseed thread to end and wait for it to finish */ 319 random_kthread_control = 0; 320 tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", 0); 321 sysctl_ctx_free(&random_clist); 322 } 323 SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_deinit, NULL); 324 325 /*- 326 * Entropy harvesting queue routine. 327 * 328 * This is supposed to be fast; do not do anything slow in here! 329 * It is also illegal (and morally reprehensible) to insert any 330 * high-rate data here. "High-rate" is defined as a data source 331 * that will usually cause lots of failures of the "Lockless read" 332 * check a few lines below. This includes the "always-on" sources 333 * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources. 334 */ 335 /* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle 336 * counters are built in, but on older hardware it will do a real time clock 337 * read which can be quite expensive. 338 */ 339 void 340 random_harvest_queue(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 341 { 342 struct harvest_event *event; 343 u_int ring_in; 344 345 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 346 if (!(harvest_context.hc_source_mask & (1 << origin))) 347 return; 348 RANDOM_HARVEST_LOCK(); 349 ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX; 350 if (ring_in != harvest_context.hc_entropy_ring.out) { 351 /* The ring is not full */ 352 event = harvest_context.hc_entropy_ring.ring + ring_in; 353 event->he_somecounter = (uint32_t)get_cyclecount(); 354 event->he_source = origin; 355 event->he_destination = harvest_context.hc_destination[origin]++; 356 event->he_bits = bits; 357 if (size <= sizeof(event->he_entropy)) { 358 event->he_size = size; 359 memcpy(event->he_entropy, entropy, size); 360 } 361 else { 362 /* Big event, so squash it */ 363 event->he_size = sizeof(event->he_entropy[0]); 364 event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event); 365 } 366 harvest_context.hc_entropy_ring.in = ring_in; 367 } 368 RANDOM_HARVEST_UNLOCK(); 369 } 370 371 /*- 372 * Entropy harvesting fast routine. 373 * 374 * This is supposed to be very fast; do not do anything slow in here! 375 * This is the right place for high-rate harvested data. 376 */ 377 void 378 random_harvest_fast(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 379 { 380 u_int pos; 381 382 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 383 /* XXX: FIX!! The above KASSERT is BS. Right now we ignore most structure and just accumulate the supplied data */ 384 if (!(harvest_context.hc_source_mask & (1 << origin))) 385 return; 386 pos = harvest_context.hc_entropy_fast_accumulator.pos; 387 harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount()); 388 harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX; 389 } 390 391 /*- 392 * Entropy harvesting direct routine. 393 * 394 * This is not supposed to be fast, but will only be used during 395 * (e.g.) booting when initial entropy is being gathered. 396 */ 397 void 398 random_harvest_direct(const void *entropy, u_int size, u_int bits, enum random_entropy_source origin) 399 { 400 struct harvest_event event; 401 402 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 403 if (!(harvest_context.hc_source_mask & (1 << origin))) 404 return; 405 size = MIN(size, sizeof(event.he_entropy)); 406 event.he_somecounter = (uint32_t)get_cyclecount(); 407 event.he_size = size; 408 event.he_bits = bits; 409 event.he_source = origin; 410 event.he_destination = harvest_context.hc_destination[origin]++; 411 memcpy(event.he_entropy, entropy, size); 412 random_harvestq_fast_process_event(&event); 413 explicit_bzero(&event, sizeof(event)); 414 } 415