randomdev_soft.c revision 137276
1/*- 2 * Copyright (c) 2000-2004 Mark R V Murray 3 * Copyright (c) 2004 Robert N. M. Watson 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: head/sys/dev/random/randomdev_soft.c 137276 2004-11-05 20:15:06Z jhb $"); 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/kernel.h> 38#include <sys/kthread.h> 39#include <sys/lock.h> 40#include <sys/malloc.h> 41#include <sys/mutex.h> 42#include <sys/poll.h> 43#include <sys/proc.h> 44#include <sys/random.h> 45#include <sys/selinfo.h> 46#include <sys/sysctl.h> 47#include <sys/uio.h> 48#include <sys/unistd.h> 49#include <sys/vnode.h> 50 51#include <machine/bus.h> 52#include <machine/cpu.h> 53 54#include <dev/random/randomdev.h> 55#include <dev/random/randomdev_soft.h> 56 57#define RANDOM_FIFO_MAX 256 /* How many events to queue up */ 58 59static void random_kthread(void *); 60static void 61random_harvest_internal(u_int64_t, const void *, u_int, 62 u_int, u_int, enum esource); 63 64struct random_systat random_yarrow = { 65 .ident = "Software, Yarrow", 66 .init = random_yarrow_init, 67 .deinit = random_yarrow_deinit, 68 .read = random_yarrow_read, 69 .write = random_yarrow_write, 70 .reseed = random_yarrow_reseed, 71 .seeded = 1, 72}; 73 74MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers"); 75 76/* 77 * The harvest mutex protects the consistency of the entropy fifos and 78 * empty fifo. 79 */ 80struct mtx harvest_mtx; 81 82/* Lockable FIFO queue holding entropy buffers */ 83struct entropyfifo { 84 int count; 85 STAILQ_HEAD(harvestlist, harvest) head; 86}; 87 88/* Empty entropy buffers */ 89static struct entropyfifo emptyfifo; 90 91#define EMPTYBUFFERS 1024 92 93/* Harvested entropy */ 94static struct entropyfifo harvestfifo[ENTROPYSOURCE]; 95 96/* <0 to end the kthread, 0 to let it run */ 97static int random_kthread_control = 0; 98 99static struct proc *random_kthread_proc; 100 101/* List for the dynamic sysctls */ 102struct sysctl_ctx_list random_clist; 103 104/* ARGSUSED */ 105static int 106random_check_boolean(SYSCTL_HANDLER_ARGS) 107{ 108 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 109 *(u_int *)(oidp->oid_arg1) = 1; 110 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 111} 112 113/* ARGSUSED */ 114void 115random_yarrow_init(void) 116{ 117 int error, i; 118 struct harvest *np; 119 struct sysctl_oid *o, *random_o, *random_sys_o, *random_sys_harvest_o; 120 enum esource e; 121 122 o = SYSCTL_ADD_NODE(&random_clist, 123 SYSCTL_STATIC_CHILDREN(_kern), 124 OID_AUTO, "random", CTLFLAG_RW, 0, 125 "Software Random Number Generator"); 126 127 random_o = o; 128 129 random_yarrow_init_alg(&random_clist, random_o); 130 131 o = SYSCTL_ADD_NODE(&random_clist, 132 SYSCTL_CHILDREN(random_o), 133 OID_AUTO, "sys", CTLFLAG_RW, 0, 134 "Entropy Device Parameters"); 135 136 random_sys_o = o; 137 138 o = SYSCTL_ADD_PROC(&random_clist, 139 SYSCTL_CHILDREN(random_sys_o), 140 OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW, 141 &random_systat.seeded, 1, random_check_boolean, "I", 142 "Seeded State"); 143 144 o = SYSCTL_ADD_NODE(&random_clist, 145 SYSCTL_CHILDREN(random_sys_o), 146 OID_AUTO, "harvest", CTLFLAG_RW, 0, 147 "Entropy Sources"); 148 149 random_sys_harvest_o = o; 150 151 o = SYSCTL_ADD_PROC(&random_clist, 152 SYSCTL_CHILDREN(random_sys_harvest_o), 153 OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW, 154 &harvest.ethernet, 1, random_check_boolean, "I", 155 "Harvest NIC entropy"); 156 o = SYSCTL_ADD_PROC(&random_clist, 157 SYSCTL_CHILDREN(random_sys_harvest_o), 158 OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW, 159 &harvest.point_to_point, 1, random_check_boolean, "I", 160 "Harvest serial net entropy"); 161 o = SYSCTL_ADD_PROC(&random_clist, 162 SYSCTL_CHILDREN(random_sys_harvest_o), 163 OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW, 164 &harvest.interrupt, 1, random_check_boolean, "I", 165 "Harvest IRQ entropy"); 166 o = SYSCTL_ADD_PROC(&random_clist, 167 SYSCTL_CHILDREN(random_sys_harvest_o), 168 OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW, 169 &harvest.swi, 0, random_check_boolean, "I", 170 "Harvest SWI entropy"); 171 172 /* Initialise the harvest fifos */ 173 STAILQ_INIT(&emptyfifo.head); 174 emptyfifo.count = 0; 175 for (i = 0; i < EMPTYBUFFERS; i++) { 176 np = malloc(sizeof(struct harvest), M_ENTROPY, M_WAITOK); 177 STAILQ_INSERT_TAIL(&emptyfifo.head, np, next); 178 } 179 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 180 STAILQ_INIT(&harvestfifo[e].head); 181 harvestfifo[e].count = 0; 182 } 183 184 mtx_init(&harvest_mtx, "entropy harvest mutex", NULL, MTX_SPIN); 185 186 /* Start the hash/reseed thread */ 187 error = kthread_create(random_kthread, NULL, 188 &random_kthread_proc, RFHIGHPID, 0, "yarrow"); 189 if (error != 0) 190 panic("Cannot create entropy maintenance thread."); 191 192 /* Register the randomness harvesting routine */ 193 random_yarrow_init_harvester(random_harvest_internal, 194 random_yarrow_read); 195} 196 197/* ARGSUSED */ 198void 199random_yarrow_deinit(void) 200{ 201 struct harvest *np; 202 enum esource e; 203 204 /* Deregister the randomness harvesting routine */ 205 random_yarrow_deinit_harvester(); 206 207 /* 208 * Command the hash/reseed thread to end and wait for it to finish 209 */ 210 random_kthread_control = -1; 211 tsleep((void *)&random_kthread_control, curthread->td_priority, "term", 212 0); 213 214 /* Destroy the harvest fifos */ 215 while (!STAILQ_EMPTY(&emptyfifo.head)) { 216 np = STAILQ_FIRST(&emptyfifo.head); 217 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 218 free(np, M_ENTROPY); 219 } 220 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 221 while (!STAILQ_EMPTY(&harvestfifo[e].head)) { 222 np = STAILQ_FIRST(&harvestfifo[e].head); 223 STAILQ_REMOVE_HEAD(&harvestfifo[e].head, next); 224 free(np, M_ENTROPY); 225 } 226 } 227 228 random_yarrow_deinit_alg(); 229 230 mtx_destroy(&harvest_mtx); 231 232 sysctl_ctx_free(&random_clist); 233} 234 235/* ARGSUSED */ 236static void 237random_kthread(void *arg __unused) 238{ 239 STAILQ_HEAD(, harvest) local_queue; 240 struct harvest *event = NULL; 241 int active, local_count; 242 enum esource source; 243 244 STAILQ_INIT(&local_queue); 245 local_count = 0; 246 247 /* Process until told to stop */ 248 for (; random_kthread_control == 0;) { 249 250 active = 0; 251 252 /* Cycle through all the entropy sources */ 253 mtx_lock_spin(&harvest_mtx); 254 for (source = RANDOM_START; source < ENTROPYSOURCE; source++) { 255 /* 256 * Drain entropy source records into a thread-local 257 * queue for processing while not holding the mutex. 258 */ 259 STAILQ_CONCAT(&local_queue, &harvestfifo[source].head); 260 local_count += harvestfifo[source].count; 261 harvestfifo[source].count = 0; 262 } 263 264 /* 265 * Deal with events, if any, dropping the mutex as we process 266 * each event. Then push the events back into the empty 267 * fifo. 268 */ 269 if (!STAILQ_EMPTY(&local_queue)) { 270 mtx_unlock_spin(&harvest_mtx); 271 STAILQ_FOREACH(event, &local_queue, next) 272 random_process_event(event); 273 mtx_lock_spin(&harvest_mtx); 274 STAILQ_CONCAT(&emptyfifo.head, &local_queue); 275 emptyfifo.count += local_count; 276 local_count = 0; 277 } 278 mtx_unlock_spin(&harvest_mtx); 279 280 KASSERT(local_count == 0, ("random_kthread: local_count %d", 281 local_count)); 282 283 /* Found nothing, so don't belabour the issue */ 284 if (!active) 285 tsleep(&harvestfifo, curthread->td_priority, "-", 286 hz / 10); 287 288 } 289 290 random_set_wakeup_exit(&random_kthread_control); 291 /* NOTREACHED */ 292} 293 294/* Entropy harvesting routine. This is supposed to be fast; do 295 * not do anything slow in here! 296 */ 297static void 298random_harvest_internal(u_int64_t somecounter, const void *entropy, 299 u_int count, u_int bits, u_int frac, enum esource origin) 300{ 301 struct harvest *event; 302 303 KASSERT(origin == RANDOM_START || origin == RANDOM_WRITE || 304 origin == RANDOM_KEYBOARD || origin == RANDOM_MOUSE || 305 origin == RANDOM_NET || origin == RANDOM_INTERRUPT || 306 origin == RANDOM_PURE || origin == ENTROPYSOURCE, 307 ("random_harvest_internal: origin %d invalid\n", origin)); 308 309 /* Lockless read to avoid lock operations if fifo is full. */ 310 if (harvestfifo[origin].count >= RANDOM_FIFO_MAX) 311 return; 312 313 mtx_lock_spin(&harvest_mtx); 314 315 /* 316 * Don't make the harvest queues too big - help to prevent low-grade 317 * entropy swamping 318 */ 319 if (harvestfifo[origin].count < RANDOM_FIFO_MAX) { 320 event = STAILQ_FIRST(&emptyfifo.head); 321 if (event != NULL) { 322 /* Add the harvested data to the fifo */ 323 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 324 harvestfifo[origin].count++; 325 event->somecounter = somecounter; 326 event->size = count; 327 event->bits = bits; 328 event->frac = frac; 329 event->source = origin; 330 331 /* XXXX Come back and make this dynamic! */ 332 count = MIN(count, HARVESTSIZE); 333 memcpy(event->entropy, entropy, count); 334 335 STAILQ_INSERT_TAIL(&harvestfifo[origin].head, 336 event, next); 337 } 338 } 339 mtx_unlock_spin(&harvest_mtx); 340} 341 342void 343random_yarrow_write(void *buf, int count) 344{ 345 int i; 346 u_int chunk; 347 348 /* 349 * Break the input up into HARVESTSIZE chunks. The writer has too 350 * much control here, so "estimate" the the entropy as zero. 351 */ 352 for (i = 0; i < count; i += HARVESTSIZE) { 353 chunk = HARVESTSIZE; 354 if (i + chunk >= count) 355 chunk = (u_int)(count - i); 356 random_harvest_internal(get_cyclecount(), (char *)buf + i, 357 chunk, 0, 0, RANDOM_WRITE); 358 } 359} 360 361void 362random_yarrow_unblock(void) 363{ 364 if (!random_systat.seeded) { 365 random_systat.seeded = 1; 366 selwakeuppri(&random_systat.rsel, PUSER); 367 wakeup(&random_systat); 368 } 369} 370