1 /*- 2 * Copyright (c) 2013 Arthur Mesh 3 * Copyright (c) 2000-2009 Mark R V Murray 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 * $FreeBSD$ 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/param.h> 35 #include <sys/systm.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/random.h> 42 #include <sys/sysctl.h> 43 #include <sys/unistd.h> 44 45 #include <dev/random/randomdev_soft.h> 46 47 #include "random_harvestq.h" 48 49 #define RANDOM_FIFO_MAX 256 /* How many events to queue up */ 50 51 MALLOC_DEFINE(M_ENTROPY, "entropy", "Entropy harvesting buffers"); 52 53 /* 54 * The harvest mutex protects the consistency of the entropy fifos and 55 * empty fifo. 56 */ 57 struct mtx harvest_mtx; 58 59 /* Lockable FIFO queue holding entropy buffers */ 60 struct entropyfifo { 61 int count; 62 STAILQ_HEAD(harvestlist, harvest) head; 63 }; 64 65 /* Empty entropy buffers */ 66 static struct entropyfifo emptyfifo; 67 68 #define EMPTYBUFFERS 1024 69 70 /* Harvested entropy */ 71 static struct entropyfifo harvestfifo[ENTROPYSOURCE]; 72 73 /* <0 to end the kthread, 0 to let it run, 1 to flush the harvest queues */ 74 int random_kthread_control = 0; 75 76 static struct proc *random_kthread_proc; 77 78 static void 79 random_kthread(void *arg) 80 { 81 STAILQ_HEAD(, harvest) local_queue; 82 struct harvest *event = NULL; 83 int local_count; 84 enum esource source; 85 event_proc_f func = arg; 86 87 STAILQ_INIT(&local_queue); 88 local_count = 0; 89 90 /* Process until told to stop */ 91 mtx_lock_spin(&harvest_mtx); 92 for (; random_kthread_control >= 0;) { 93 94 /* Cycle through all the entropy sources */ 95 for (source = RANDOM_START; source < ENTROPYSOURCE; source++) { 96 /* 97 * Drain entropy source records into a thread-local 98 * queue for processing while not holding the mutex. 99 */ 100 STAILQ_CONCAT(&local_queue, &harvestfifo[source].head); 101 local_count += harvestfifo[source].count; 102 harvestfifo[source].count = 0; 103 } 104 105 /* 106 * Deal with events, if any, dropping the mutex as we process 107 * each event. Then push the events back into the empty 108 * fifo. 109 */ 110 if (!STAILQ_EMPTY(&local_queue)) { 111 mtx_unlock_spin(&harvest_mtx); 112 STAILQ_FOREACH(event, &local_queue, next) 113 func(event); 114 mtx_lock_spin(&harvest_mtx); 115 STAILQ_CONCAT(&emptyfifo.head, &local_queue); 116 emptyfifo.count += local_count; 117 local_count = 0; 118 } 119 120 KASSERT(local_count == 0, ("random_kthread: local_count %d", 121 local_count)); 122 123 /* 124 * If a queue flush was commanded, it has now happened, 125 * and we can mark this by resetting the command. 126 */ 127 if (random_kthread_control == 1) 128 random_kthread_control = 0; 129 130 /* Work done, so don't belabour the issue */ 131 msleep_spin_sbt(&random_kthread_control, &harvest_mtx, 132 "-", SBT_1S / 10, 0, C_PREL(1)); 133 134 } 135 mtx_unlock_spin(&harvest_mtx); 136 137 random_set_wakeup_exit(&random_kthread_control); 138 /* NOTREACHED */ 139 } 140 141 void 142 random_harvestq_init(event_proc_f cb) 143 { 144 int error, i; 145 struct harvest *np; 146 enum esource e; 147 148 /* Initialise the harvest fifos */ 149 STAILQ_INIT(&emptyfifo.head); 150 emptyfifo.count = 0; 151 for (i = 0; i < EMPTYBUFFERS; i++) { 152 np = malloc(sizeof(struct harvest), M_ENTROPY, M_WAITOK); 153 STAILQ_INSERT_TAIL(&emptyfifo.head, np, next); 154 } 155 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 156 STAILQ_INIT(&harvestfifo[e].head); 157 harvestfifo[e].count = 0; 158 } 159 160 mtx_init(&harvest_mtx, "entropy harvest mutex", NULL, MTX_SPIN); 161 162 163 /* Start the hash/reseed thread */ 164 error = kproc_create(random_kthread, cb, 165 &random_kthread_proc, RFHIGHPID, 0, "rand_harvestq"); /* RANDOM_CSPRNG_NAME */ 166 167 if (error != 0) 168 panic("Cannot create entropy maintenance thread."); 169 } 170 171 void 172 random_harvestq_deinit(void) 173 { 174 struct harvest *np; 175 enum esource e; 176 177 /* Destroy the harvest fifos */ 178 while (!STAILQ_EMPTY(&emptyfifo.head)) { 179 np = STAILQ_FIRST(&emptyfifo.head); 180 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 181 free(np, M_ENTROPY); 182 } 183 for (e = RANDOM_START; e < ENTROPYSOURCE; e++) { 184 while (!STAILQ_EMPTY(&harvestfifo[e].head)) { 185 np = STAILQ_FIRST(&harvestfifo[e].head); 186 STAILQ_REMOVE_HEAD(&harvestfifo[e].head, next); 187 free(np, M_ENTROPY); 188 } 189 } 190 191 mtx_destroy(&harvest_mtx); 192 } 193 194 /* 195 * Entropy harvesting routine. This is supposed to be fast; do 196 * not do anything slow in here! 197 */ 198 void 199 random_harvestq_internal(u_int64_t somecounter, const void *entropy, 200 u_int count, u_int bits, u_int frac, enum esource origin) 201 { 202 struct harvest *event; 203 204 KASSERT(origin >= RANDOM_START && origin <= RANDOM_PURE, 205 ("random_harvest_internal: origin %d invalid\n", origin)); 206 207 /* Lockless read to avoid lock operations if fifo is full. */ 208 if (harvestfifo[origin].count >= RANDOM_FIFO_MAX) 209 return; 210 211 mtx_lock_spin(&harvest_mtx); 212 213 /* 214 * Don't make the harvest queues too big - help to prevent low-grade 215 * entropy swamping 216 */ 217 if (harvestfifo[origin].count < RANDOM_FIFO_MAX) { 218 event = STAILQ_FIRST(&emptyfifo.head); 219 if (event != NULL) { 220 /* Add the harvested data to the fifo */ 221 STAILQ_REMOVE_HEAD(&emptyfifo.head, next); 222 harvestfifo[origin].count++; 223 event->somecounter = somecounter; 224 event->size = count; 225 event->bits = bits; 226 event->frac = frac; 227 event->source = origin; 228 229 /* XXXX Come back and make this dynamic! */ 230 count = MIN(count, HARVESTSIZE); 231 memcpy(event->entropy, entropy, count); 232 233 #if 0 234 { 235 int i; 236 printf("Harvest:%16jX ", event->somecounter); 237 for (i = 0; i < event->size; i++) 238 printf("%02X", event->entropy[i]); 239 for (; i < 16; i++) 240 printf(" "); 241 printf(" %2d 0x%2X.%03X %02X\n", event->size, event->bits, event->frac, event->source); 242 } 243 #endif 244 245 STAILQ_INSERT_TAIL(&harvestfifo[origin].head, 246 event, next); 247 } 248 } 249 mtx_unlock_spin(&harvest_mtx); 250 } 251 252