randomdev_soft.c revision 133465
1/*- 2 * Copyright (c) 2000-2004 Mark R V Murray 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD: head/sys/dev/random/randomdev_soft.c 133465 2004-08-11 03:33:32Z rwatson $"); 30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/bus.h> 34#include <sys/conf.h> 35#include <sys/fcntl.h> 36#include <sys/kernel.h> 37#include <sys/kthread.h> 38#include <sys/lock.h> 39#include <sys/malloc.h> 40#include <sys/mutex.h> 41#include <sys/poll.h> 42#include <sys/proc.h> 43#include <sys/random.h> 44#include <sys/selinfo.h> 45#include <sys/sysctl.h> 46#include <sys/uio.h> 47#include <sys/unistd.h> 48#include <sys/vnode.h> 49 50#include <machine/bus.h> 51#include <machine/cpu.h> 52 53#include <dev/random/randomdev.h> 54#include <dev/random/randomdev_soft.h> 55 56#define RANDOM_FIFO_MAX 256 /* How many events to queue up */ 57 58static void random_kthread(void *); 59static void 60random_harvest_internal(u_int64_t, const void *, u_int, 61 u_int, u_int, enum esource); 62 63struct random_systat random_yarrow = { 64 .ident = "Software, Yarrow", 65 .init = random_yarrow_init, 66 .deinit = random_yarrow_deinit, 67 .read = random_yarrow_read, 68 .write = random_yarrow_write, 69 .reseed = random_yarrow_reseed, 70 .seeded = 1, 71}; 72 73MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers"); 74 75/* Lockable FIFO queue holding entropy buffers */ 76struct entropyfifo { 77 struct mtx lock; 78 int count; 79 STAILQ_HEAD(harvestlist, harvest) head; 80}; 81 82/* Empty entropy buffers */ 83static struct entropyfifo emptyfifo; 84 85#define EMPTYBUFFERS 1024 86 87/* Harvested entropy */ 88static struct entropyfifo harvestfifo[ENTROPYSOURCE]; 89 90/* <0 to end the kthread, 0 to let it run */ 91static int random_kthread_control = 0; 92 93static struct proc *random_kthread_proc; 94 95/* List for the dynamic sysctls */ 96struct sysctl_ctx_list random_clist; 97 98/* ARGSUSED */ 99static int 100random_check_boolean(SYSCTL_HANDLER_ARGS) 101{ 102 if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0) 103 *(u_int *)(oidp->oid_arg1) = 1; 104 return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 105} 106 107/* ARGSUSED */ 108void 109random_yarrow_init(void) 110{ 111 int error, i; 112 struct harvest *np; 113 struct sysctl_oid *o, *random_o, *random_sys_o, *random_sys_harvest_o; 114 enum esource e; 115 116 o = SYSCTL_ADD_NODE(&random_clist, 117 SYSCTL_STATIC_CHILDREN(_kern), 118 OID_AUTO, "random", CTLFLAG_RW, 0, 119 "Software Random Number Generator"); 120 121 random_o = o; 122 123 random_yarrow_init_alg(&random_clist, random_o); 124 125 o = SYSCTL_ADD_NODE(&random_clist, 126 SYSCTL_CHILDREN(random_o), 127 OID_AUTO, "sys", CTLFLAG_RW, 0, 128 "Entropy Device Parameters"); 129 130 random_sys_o = o; 131 132 o = SYSCTL_ADD_PROC(&random_clist, 133 SYSCTL_CHILDREN(random_sys_o), 134 OID_AUTO, "seeded", CTLTYPE_INT | CTLFLAG_RW, 135 &random_systat.seeded, 1, random_check_boolean, "I", 136 "Seeded State"); 137 138 o = SYSCTL_ADD_NODE(&random_clist, 139 SYSCTL_CHILDREN(random_sys_o), 140 OID_AUTO, "harvest", CTLFLAG_RW, 0, 141 "Entropy Sources"); 142 143 random_sys_harvest_o = o; 144 145 o = SYSCTL_ADD_PROC(&random_clist, 146 SYSCTL_CHILDREN(random_sys_harvest_o), 147 OID_AUTO, "ethernet", CTLTYPE_INT | CTLFLAG_RW, 148 &harvest.ethernet, 1, random_check_boolean, "I", 149 "Harvest NIC entropy"); 150 o = SYSCTL_ADD_PROC(&random_clist, 151 SYSCTL_CHILDREN(random_sys_harvest_o), 152 OID_AUTO, "point_to_point", CTLTYPE_INT | CTLFLAG_RW, 153 &harvest.point_to_point, 1, random_check_boolean, "I", 154 "Harvest serial net entropy"); 155 o = SYSCTL_ADD_PROC(&random_clist, 156 SYSCTL_CHILDREN(random_sys_harvest_o), 157 OID_AUTO, "interrupt", CTLTYPE_INT | CTLFLAG_RW, 158 &harvest.interrupt, 1, random_check_boolean, "I", 159 "Harvest IRQ entropy"); 160 o = SYSCTL_ADD_PROC(&random_clist, 161 SYSCTL_CHILDREN(random_sys_harvest_o), 162 OID_AUTO, "swi", CTLTYPE_INT | CTLFLAG_RW, 163 &harvest.swi, 0, random_check_boolean, "I", 164 "Harvest SWI entropy"); 165 166 /* Initialise the harvest fifos */ 167 STAILQ_INIT(&emptyfifo.head); 168 emptyfifo.count = 0; 169 mtx_init(&emptyfifo.lock, "entropy harvest buffers", NULL, MTX_SPIN); 170 for (i = 0; i < EMPTYBUFFERS; i++) { 171 np = malloc(sizeof(struct harvest), M_ENTROPY, M_WAITOK); 172 STAILQ_INSERT_TAIL(&emptyfifo.head, np, next); 173 } 174 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 175 STAILQ_INIT(&harvestfifo[e].head); 176 harvestfifo[e].count = 0; 177 mtx_init(&harvestfifo[e].lock, "entropy harvest", NULL, 178 MTX_SPIN); 179 } 180 181 /* Start the hash/reseed thread */ 182 error = kthread_create(random_kthread, NULL, 183 &random_kthread_proc, RFHIGHPID, 0, "yarrow"); 184 if (error != 0) 185 panic("Cannot create entropy maintenance thread."); 186 187 /* Register the randomness harvesting routine */ 188 random_yarrow_init_harvester(random_harvest_internal, 189 random_yarrow_read); 190} 191 192/* ARGSUSED */ 193void 194random_yarrow_deinit(void) 195{ 196 struct harvest *np; 197 enum esource e; 198 199 /* Deregister the randomness harvesting routine */ 200 random_yarrow_deinit_harvester(); 201 202 /* 203 * Command the hash/reseed thread to end and wait for it to finish 204 */ 205 random_kthread_control = -1; 206 tsleep((void *)&random_kthread_control, PUSER, "term", 0); 207 208 /* Destroy the harvest fifos */ 209 while (!STAILQ_EMPTY(&emptyfifo.head)) { 210 np = STAILQ_FIRST(&emptyfifo.head); 211 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 212 free(np, M_ENTROPY); 213 } 214 mtx_destroy(&emptyfifo.lock); 215 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 216 while (!STAILQ_EMPTY(&harvestfifo[e].head)) { 217 np = STAILQ_FIRST(&harvestfifo[e].head); 218 STAILQ_REMOVE_HEAD(&harvestfifo[e].head, next); 219 free(np, M_ENTROPY); 220 } 221 mtx_destroy(&harvestfifo[e].lock); 222 } 223 224 random_yarrow_deinit_alg(); 225 226 sysctl_ctx_free(&random_clist); 227} 228 229/* ARGSUSED */ 230static void 231random_kthread(void *arg __unused) 232{ 233 struct harvest *event = NULL; 234 int found, active; 235 enum esource source; 236 237 /* Process until told to stop */ 238 for (; random_kthread_control == 0;) { 239 240 active = 0; 241 242 /* Cycle through all the entropy sources */ 243 for (source = RANDOM_START; source < ENTROPYSOURCE; source++) { 244 245 found = 0; 246 247 /* Lock up queue draining */ 248 mtx_lock_spin(&harvestfifo[source].lock); 249 250 if (!STAILQ_EMPTY(&harvestfifo[source].head)) { 251 252 /* Get a harvested entropy event */ 253 harvestfifo[source].count--; 254 event = STAILQ_FIRST(&harvestfifo[source].head); 255 STAILQ_REMOVE_HEAD(&harvestfifo[source].head, 256 next); 257 258 active = found = 1; 259 260 } 261 /* Unlock the queue */ 262 mtx_unlock_spin(&harvestfifo[source].lock); 263 264 /* Deal with the event and dispose of it */ 265 if (found) { 266 267 random_process_event(event); 268 269 /* Lock the empty event buffer fifo */ 270 mtx_lock_spin(&emptyfifo.lock); 271 272 STAILQ_INSERT_TAIL(&emptyfifo.head, event, 273 next); 274 275 mtx_unlock_spin(&emptyfifo.lock); 276 277 } 278 } 279 280 /* Found nothing, so don't belabour the issue */ 281 if (!active) 282 tsleep(&harvestfifo, PUSER, "-", hz / 10); 283 284 } 285 286 random_set_wakeup_exit(&random_kthread_control); 287 /* NOTREACHED */ 288} 289 290/* Entropy harvesting routine. This is supposed to be fast; do 291 * not do anything slow in here! 292 */ 293static void 294random_harvest_internal(u_int64_t somecounter, const void *entropy, 295 u_int count, u_int bits, u_int frac, enum esource origin) 296{ 297 struct harvest *event; 298 299 /* Lockless read to avoid lock operations if fifo is full. */ 300 if (harvestfifo[origin].count >= RANDOM_FIFO_MAX) 301 return; 302 303 /* Lock the particular fifo */ 304 mtx_lock_spin(&harvestfifo[origin].lock); 305 306 /* 307 * Don't make the harvest queues too big - help to prevent low-grade 308 * entropy swamping 309 */ 310 if (harvestfifo[origin].count < RANDOM_FIFO_MAX) { 311 312 /* Lock the empty event buffer fifo */ 313 mtx_lock_spin(&emptyfifo.lock); 314 315 if (!STAILQ_EMPTY(&emptyfifo.head)) { 316 event = STAILQ_FIRST(&emptyfifo.head); 317 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 318 } else 319 event = NULL; 320 321 mtx_unlock_spin(&emptyfifo.lock); 322 323 /* If we didn't obtain a buffer, tough */ 324 if (event) { 325 326 /* Add the harvested data to the fifo */ 327 harvestfifo[origin].count++; 328 event->somecounter = somecounter; 329 event->size = count; 330 event->bits = bits; 331 event->frac = frac; 332 event->source = origin; 333 334 /* XXXX Come back and make this dynamic! */ 335 count = MIN(count, HARVESTSIZE); 336 memcpy(event->entropy, entropy, count); 337 338 STAILQ_INSERT_TAIL(&harvestfifo[origin].head, 339 event, next); 340 } 341 } 342 mtx_unlock_spin(&harvestfifo[origin].lock); 343 344} 345 346void 347random_yarrow_write(void *buf, int count) 348{ 349 int i; 350 u_int chunk; 351 352 /* 353 * Break the input up into HARVESTSIZE chunks. The writer has too 354 * much control here, so "estimate" the the entropy as zero. 355 */ 356 for (i = 0; i < count; i += HARVESTSIZE) { 357 chunk = HARVESTSIZE; 358 if (i + chunk >= count) 359 chunk = (u_int)(count - i); 360 random_harvest_internal(get_cyclecount(), (char *)buf + i, 361 chunk, 0, 0, RANDOM_WRITE); 362 } 363} 364 365void 366random_yarrow_unblock(void) 367{ 368 if (!random_systat.seeded) { 369 random_systat.seeded = 1; 370 selwakeuppri(&random_systat.rsel, PUSER); 371 wakeup(&random_systat); 372 } 373} 374