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 the consistency of the entropy Fifos and 78 * empty fifo and other associated structures. 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 * The ring.in variable needs locking as there are multiple 99 * sources to the ring. Only the sources may change ring.in, 100 * but the consumer may examine it. 101 * 102 * The ring.out variable does not need locking as there is 103 * only one consumer. Only the consumer may change ring.out, 104 * but the sources may examine it. 105 */ 106 struct entropy_ring { 107 struct harvest_event ring[RANDOM_RING_MAX]; 108 volatile u_int in; 109 volatile u_int out; 110 } hc_entropy_ring; 111 struct fast_entropy_accumulator { 112 volatile u_int pos; 113 uint32_t buf[8]; 114 } hc_entropy_fast_accumulator; 115 } harvest_context; 116 117 static struct kproc_desc random_proc_kp = { 118 "rand_harvestq", 119 random_kthread, 120 &harvest_context.hc_kthread_proc, 121 }; 122 123 124 /* Pass the given event straight through to Fortuna/Yarrow/Whatever. */ 125 static __inline void 126 random_harvestq_fast_process_event(struct harvest_event *event) 127 { 128 if (random_alg_context.ra_event_processor) 129 random_alg_context.ra_event_processor(event); 130 } 131 132 static void 133 random_kthread(void) 134 { 135 u_int maxloop, ring_out, i; 136 137 /* 138 * Locking is not needed as this is the only place we modify ring.out, and 139 * we only examine ring.in without changing it. Both of these are volatile, 140 * and this is a unique thread. 141 */ 142 for (random_kthread_control = 1; random_kthread_control;) { 143 /* Deal with events, if any. Restrict the number we do in one go. */ 144 maxloop = RANDOM_RING_MAX; 145 while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) { 146 ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX; 147 random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out); 148 harvest_context.hc_entropy_ring.out = ring_out; 149 if (!--maxloop) 150 break; 151 } 152 random_sources_feed(); 153 /* XXX: FIX!! This This seems a little slow; 8 items every 0.1s from UMA? */ 154 for (i = 0; i < RANDOM_ACCUM_MAX; i++) { 155 if (harvest_context.hc_entropy_fast_accumulator.buf[i]) { 156 random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), 4, RANDOM_FAST); 157 harvest_context.hc_entropy_fast_accumulator.buf[i] = 0; 158 } 159 } 160 /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */ 161 tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10, 0, C_PREL(1)); 162 } 163 wakeup(&harvest_context.hc_kthread_proc); 164 kproc_exit(0); 165 /* NOTREACHED */ 166 } 167 SYSINIT(random_device_h_proc, SI_SUB_CREATE_INIT, SI_ORDER_ANY, kproc_start, &random_proc_kp); 168 169 /* ARGSUSED */ 170 RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_MASK); 171 172 /* ARGSUSED */ 173 static int 174 random_print_harvestmask(SYSCTL_HANDLER_ARGS) 175 { 176 struct sbuf sbuf; 177 int error, i; 178 179 error = sysctl_wire_old_buffer(req, 0); 180 if (error == 0) { 181 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 182 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) 183 sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0"); 184 error = sbuf_finish(&sbuf); 185 sbuf_delete(&sbuf); 186 } 187 return (error); 188 } 189 190 static const char *(random_source_descr[]) = { 191 "CACHED", 192 "ATTACH", 193 "KEYBOARD", 194 "MOUSE", 195 "NET_TUN", 196 "NET_ETHER", 197 "NET_NG", 198 "INTERRUPT", 199 "SWI", 200 "FS_ATIME", 201 "HIGH_PERFORMANCE", /* ENVIRONMENTAL_END */ 202 "PURE_OCTEON", 203 "PURE_SAFE", 204 "PURE_GLXSB", 205 "PURE_UBSEC", 206 "PURE_HIFN", 207 "PURE_RDRAND", 208 "PURE_NEHEMIAH", 209 "PURE_RNDTEST", 210 /* "ENTROPYSOURCE" */ 211 }; 212 213 /* ARGSUSED */ 214 static int 215 random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS) 216 { 217 struct sbuf sbuf; 218 int error, i; 219 220 error = sysctl_wire_old_buffer(req, 0); 221 if (error == 0) { 222 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 223 for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) { 224 sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ","); 225 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : ""); 226 sbuf_cat(&sbuf, random_source_descr[i]); 227 sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : ""); 228 } 229 error = sbuf_finish(&sbuf); 230 sbuf_delete(&sbuf); 231 } 232 return (error); 233 } 234 235 /* ARGSUSED */ 236 static void 237 random_harvestq_init(void *unused __unused) 238 { 239 struct sysctl_oid *random_sys_o; 240 241 if (bootverbose) 242 printf("random: %s\n", __func__); 243 random_sys_o = SYSCTL_ADD_NODE(&random_clist, 244 SYSCTL_STATIC_CHILDREN(_kern_random), 245 OID_AUTO, "harvest", CTLFLAG_RW, 0, 246 "Entropy Device Parameters"); 247 harvest_context.hc_source_mask = RANDOM_HARVEST_EVERYTHING_MASK; 248 SYSCTL_ADD_PROC(&random_clist, 249 SYSCTL_CHILDREN(random_sys_o), 250 OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW, 251 &harvest_context.hc_source_mask, 0, 252 random_check_uint_harvestmask, "IU", 253 "Entropy harvesting mask"); 254 SYSCTL_ADD_PROC(&random_clist, 255 SYSCTL_CHILDREN(random_sys_o), 256 OID_AUTO, "mask_bin", CTLTYPE_STRING | CTLFLAG_RD, 257 NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)"); 258 SYSCTL_ADD_PROC(&random_clist, 259 SYSCTL_CHILDREN(random_sys_o), 260 OID_AUTO, "mask_symbolic", CTLTYPE_STRING | CTLFLAG_RD, 261 NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)"); 262 RANDOM_HARVEST_INIT_LOCK(); 263 harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0; 264 } 265 SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL); 266 267 /* 268 * This is used to prime the RNG by grabbing any early random stuff 269 * known to the kernel, and inserting it directly into the hashing 270 * module, e.g. Fortuna or Yarrow. 271 */ 272 /* ARGSUSED */ 273 static void 274 random_harvestq_prime(void *unused __unused) 275 { 276 struct harvest_event event; 277 size_t count, size, i; 278 uint8_t *keyfile, *data; 279 280 /* 281 * Get entropy that may have been preloaded by loader(8) 282 * and use it to pre-charge the entropy harvest queue. 283 */ 284 keyfile = preload_search_by_type(RANDOM_HARVESTQ_BOOT_ENTROPY_FILE); 285 if (keyfile != NULL) { 286 data = preload_fetch_addr(keyfile); 287 size = preload_fetch_size(keyfile); 288 if (data != NULL && size != 0) { 289 for (i = 0; i < size; i += sizeof(event.he_entropy)) { 290 count = sizeof(event.he_entropy); 291 event.he_somecounter = (uint32_t)get_cyclecount(); 292 event.he_size = count; 293 event.he_bits = count/4; /* Underestimate the size for Yarrow */ 294 event.he_source = RANDOM_CACHED; 295 event.he_destination = harvest_context.hc_destination[0]++; 296 memcpy(event.he_entropy, data + i, sizeof(event.he_entropy)); 297 random_harvestq_fast_process_event(&event); 298 explicit_bzero(&event, sizeof(event)); 299 } 300 explicit_bzero(data, size); 301 if (bootverbose) 302 printf("random: read %zu bytes from preloaded cache\n", size); 303 } else 304 if (bootverbose) 305 printf("random: no preloaded entropy cache\n"); 306 } 307 } 308 SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_FOURTH, random_harvestq_prime, NULL); 309 310 /* ARGSUSED */ 311 static void 312 random_harvestq_deinit(void *unused __unused) 313 { 314 315 /* Command the hash/reseed thread to end and wait for it to finish */ 316 random_kthread_control = 0; 317 tsleep(&harvest_context.hc_kthread_proc, 0, "term", 0); 318 sysctl_ctx_free(&random_clist); 319 } 320 SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_deinit, NULL); 321 322 /*- 323 * Entropy harvesting queue routine. 324 * 325 * This is supposed to be fast; do not do anything slow in here! 326 * It is also illegal (and morally reprehensible) to insert any 327 * high-rate data here. "High-rate" is defined as a data source 328 * that will usually cause lots of failures of the "Lockless read" 329 * check a few lines below. This includes the "always-on" sources 330 * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources. 331 */ 332 /* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle 333 * counters are built in, but on older hardware it will do a real time clock 334 * read which can be quite expensive. 335 */ 336 void 337 random_harvest_queue(const void *entropy, u_int count, u_int bits, enum random_entropy_source origin) 338 { 339 struct harvest_event *event; 340 u_int ring_in; 341 342 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 343 if (!(harvest_context.hc_source_mask & (1 << origin))) 344 return; 345 RANDOM_HARVEST_LOCK(); 346 ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX; 347 if (ring_in != harvest_context.hc_entropy_ring.out) { 348 /* The ring is not full */ 349 event = harvest_context.hc_entropy_ring.ring + ring_in; 350 event->he_somecounter = (uint32_t)get_cyclecount(); 351 event->he_source = origin; 352 event->he_destination = harvest_context.hc_destination[origin]++; 353 event->he_bits = bits; 354 if (count <= sizeof(event->he_entropy)) { 355 event->he_size = count; 356 memcpy(event->he_entropy, entropy, count); 357 } 358 else { 359 /* Big event, so squash it */ 360 event->he_size = sizeof(event->he_entropy[0]); 361 event->he_entropy[0] = jenkins_hash(entropy, count, (uint32_t)(uintptr_t)event); 362 } 363 harvest_context.hc_entropy_ring.in = ring_in; 364 } 365 RANDOM_HARVEST_UNLOCK(); 366 } 367 368 /*- 369 * Entropy harvesting fast routine. 370 * 371 * This is supposed to be very fast; do not do anything slow in here! 372 * This is the right place for high-rate harvested data. 373 */ 374 void 375 random_harvest_fast(const void *entropy, u_int count, u_int bits, enum random_entropy_source origin) 376 { 377 u_int pos; 378 379 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 380 /* XXX: FIX!! The above KASSERT is BS. Right now we ignore most structure and just accumulate the supplied data */ 381 if (!(harvest_context.hc_source_mask & (1 << origin))) 382 return; 383 pos = harvest_context.hc_entropy_fast_accumulator.pos; 384 harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, count, (uint32_t)get_cyclecount()); 385 harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX; 386 } 387 388 /*- 389 * Entropy harvesting direct routine. 390 * 391 * This is not supposed to be fast, but will only be used during 392 * (e.g.) booting when initial entropy is being gathered. 393 */ 394 void 395 random_harvest_direct(const void *entropy, u_int count, u_int bits, enum random_entropy_source origin) 396 { 397 struct harvest_event event; 398 399 KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); 400 if (!(harvest_context.hc_source_mask & (1 << origin))) 401 return; 402 count = MIN(count, sizeof(event.he_entropy)); 403 event.he_somecounter = (uint32_t)get_cyclecount(); 404 event.he_size = count; 405 event.he_bits = bits; 406 event.he_source = origin; 407 event.he_destination = harvest_context.hc_destination[origin]++; 408 memcpy(event.he_entropy, entropy, count); 409 random_harvestq_fast_process_event(&event); 410 explicit_bzero(&event, sizeof(event)); 411 } 412