sys/dev/random/yarrow.c

   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("$FreeBSD$");
  30
  31 #include <sys/param.h>
  32 #include <sys/kernel.h>
  33 #include <sys/lock.h>
  34 #include <sys/malloc.h>
  35 #include <sys/mutex.h>
  36 #include <sys/random.h>
  37 #include <sys/sysctl.h>
  38 #include <sys/systm.h>
  39
  40 #include <crypto/rijndael/rijndael-api-fst.h>
  41 #include <crypto/sha2/sha2.h>
  42
  43 #include <dev/random/hash.h>
  44 #include <dev/random/randomdev_soft.h>
  45 #include <dev/random/yarrow.h>
  46
  47 RANDOM_CHECK_UINT(gengateinterval, 4, 64);
  48 RANDOM_CHECK_UINT(bins, 2, 16);
  49 RANDOM_CHECK_UINT(fastthresh, BLOCKSIZE/4, BLOCKSIZE);
  50 RANDOM_CHECK_UINT(slowthresh, BLOCKSIZE/4, BLOCKSIZE);
  51 RANDOM_CHECK_UINT(slowoverthresh, 1, 5);
  52
  53 /* Structure holding the entropy state */
  54 static struct random_state random_state;
  55
  56 static void generator_gate(void);
  57 static void reseed(u_int);
  58
  59 /* The reseed thread mutex */
  60 struct mtx random_reseed_mtx;
  61
  62 /* Process a single stochastic event off the harvest queue */
  63 void
  64 random_process_event(struct harvest *event)
  65 {
  66         u_int pl, overthreshhold[2];
  67         struct source *source;
  68         enum esource src;
  69
  70         /* Unpack the event into the appropriate source accumulator */
  71         pl = random_state.which;
  72         source = &random_state.pool[pl].source[event->source];
  73         yarrow_hash_iterate(&random_state.pool[pl].hash, event->entropy,
  74                 sizeof(event->entropy));
  75         yarrow_hash_iterate(&random_state.pool[pl].hash, &event->somecounter,
  76                 sizeof(event->somecounter));
  77         source->frac += event->frac;
  78         source->bits += event->bits + source->frac/1024;
  79         source->frac %= 1024;
  80
  81         /* Count the over-threshold sources in each pool */
  82         for (pl = 0; pl < 2; pl++) {
  83                 overthreshhold[pl] = 0;
  84                 for (src = RANDOM_START; src < ENTROPYSOURCE; src++) {
  85                         if (random_state.pool[pl].source[src].bits
  86                                 > random_state.pool[pl].thresh)
  87                                 overthreshhold[pl]++;
  88                 }
  89         }
  90
  91         /* if any fast source over threshhold, reseed */
  92         if (overthreshhold[FAST])
  93                 reseed(FAST);
  94
  95         /* if enough slow sources are over threshhold, reseed */
  96         if (overthreshhold[SLOW] >= random_state.slowoverthresh)
  97                 reseed(SLOW);
  98
  99         /* Invert the fast/slow pool selector bit */
 100         random_state.which = !random_state.which;
 101 }
 102
 103 void
 104 random_yarrow_init_alg(struct sysctl_ctx_list *clist, struct sysctl_oid *in_o)
 105 {
 106         int i;
 107         struct sysctl_oid *random_yarrow_o;
 108
 109         /* Yarrow parameters. Do not adjust these unless you have
 110          * have a very good clue about what they do!
 111          */
 112         random_yarrow_o = SYSCTL_ADD_NODE(clist,
 113                 SYSCTL_CHILDREN(in_o),
 114                 OID_AUTO, "yarrow", CTLFLAG_RW, 0,
 115                 "Yarrow Parameters");
 116
 117         SYSCTL_ADD_PROC(clist,
 118                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 119                 "gengateinterval", CTLTYPE_INT|CTLFLAG_RW,
 120                 &random_state.gengateinterval, 10,
 121                 random_check_uint_gengateinterval, "I",
 122                 "Generation gate interval");
 123
 124         SYSCTL_ADD_PROC(clist,
 125                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 126                 "bins", CTLTYPE_INT|CTLFLAG_RW,
 127                 &random_state.bins, 10,
 128                 random_check_uint_bins, "I",
 129                 "Execution time tuner");
 130
 131         SYSCTL_ADD_PROC(clist,
 132                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 133                 "fastthresh", CTLTYPE_INT|CTLFLAG_RW,
 134                 &random_state.pool[0].thresh, (3*BLOCKSIZE)/4,
 135                 random_check_uint_fastthresh, "I",
 136                 "Fast reseed threshold");
 137
 138         SYSCTL_ADD_PROC(clist,
 139                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 140                 "slowthresh", CTLTYPE_INT|CTLFLAG_RW,
 141                 &random_state.pool[1].thresh, BLOCKSIZE,
 142                 random_check_uint_slowthresh, "I",
 143                 "Slow reseed threshold");
 144
 145         SYSCTL_ADD_PROC(clist,
 146                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 147                 "slowoverthresh", CTLTYPE_INT|CTLFLAG_RW,
 148                 &random_state.slowoverthresh, 2,
 149                 random_check_uint_slowoverthresh, "I",
 150                 "Slow over-threshold reseed");
 151
 152         random_state.gengateinterval = 10;
 153         random_state.bins = 10;
 154         random_state.pool[0].thresh = (3*BLOCKSIZE)/4;
 155         random_state.pool[1].thresh = BLOCKSIZE;
 156         random_state.slowoverthresh = 2;
 157         random_state.which = FAST;
 158
 159         /* Initialise the fast and slow entropy pools */
 160         for (i = 0; i < 2; i++)
 161                 yarrow_hash_init(&random_state.pool[i].hash);
 162
 163         /* Clear the counter */
 164         for (i = 0; i < 4; i++)
 165                 random_state.counter[i] = 0;
 166
 167         /* Set up a lock for the reseed process */
 168         mtx_init(&random_reseed_mtx, "random reseed", NULL, MTX_DEF);
 169 }
 170
 171 void
 172 random_yarrow_deinit_alg(void)
 173 {
 174         mtx_destroy(&random_reseed_mtx);
 175 }
 176
 177 static void
 178 reseed(u_int fastslow)
 179 {
 180         /* Interrupt-context stack is a limited resource; make large
 181          * structures static.
 182          */
 183         static u_char v[TIMEBIN][KEYSIZE];      /* v[i] */
 184         static struct yarrowhash context;
 185         u_char hash[KEYSIZE];                   /* h' */
 186         u_char temp[KEYSIZE];
 187         u_int i;
 188         enum esource j;
 189
 190         /* The reseed task must not be jumped on */
 191         mtx_lock(&random_reseed_mtx);
 192
 193         /* 1. Hash the accumulated entropy into v[0] */
 194
 195         yarrow_hash_init(&context);
 196         /* Feed the slow pool hash in if slow */
 197         if (fastslow == SLOW)
 198                 yarrow_hash_iterate(&context,
 199                         &random_state.pool[SLOW].hash,
 200                         sizeof(struct yarrowhash));
 201         yarrow_hash_iterate(&context,
 202                 &random_state.pool[FAST].hash, sizeof(struct yarrowhash));
 203         yarrow_hash_finish(&context, v[0]);
 204
 205         /* 2. Compute hash values for all v. _Supposed_ to be computationally
 206          *    intensive.
 207          */
 208
 209         if (random_state.bins > TIMEBIN)
 210                 random_state.bins = TIMEBIN;
 211         for (i = 1; i < random_state.bins; i++) {
 212                 yarrow_hash_init(&context);
 213                 /* v[i] #= h(v[i - 1]) */
 214                 yarrow_hash_iterate(&context, v[i - 1], KEYSIZE);
 215                 /* v[i] #= h(v[0]) */
 216                 yarrow_hash_iterate(&context, v[0], KEYSIZE);
 217                 /* v[i] #= h(i) */
 218                 yarrow_hash_iterate(&context, &i, sizeof(u_int));
 219                 /* Return the hashval */
 220                 yarrow_hash_finish(&context, v[i]);
 221         }
 222
 223         /* 3. Compute a new key; h' is the identity function here;
 224          *    it is not being ignored!
 225          */
 226
 227         yarrow_hash_init(&context);
 228         yarrow_hash_iterate(&context, &random_state.key, KEYSIZE);
 229         for (i = 1; i < random_state.bins; i++)
 230                 yarrow_hash_iterate(&context, &v[i], KEYSIZE);
 231         yarrow_hash_finish(&context, temp);
 232         yarrow_encrypt_init(&random_state.key, temp);
 233
 234         /* 4. Recompute the counter */
 235
 236         for (i = 0; i < 4; i++)
 237                 random_state.counter[i] = 0;
 238         yarrow_encrypt(&random_state.key, random_state.counter, temp);
 239         memcpy(random_state.counter, temp, sizeof(random_state.counter));
 240
 241         /* 5. Reset entropy estimate accumulators to zero */
 242
 243         for (i = 0; i <= fastslow; i++) {
 244                 for (j = RANDOM_START; j < ENTROPYSOURCE; j++) {
 245                         random_state.pool[i].source[j].bits = 0;
 246                         random_state.pool[i].source[j].frac = 0;
 247                 }
 248         }
 249
 250         /* 6. Wipe memory of intermediate values */
 251
 252         memset((void *)v, 0, sizeof(v));
 253         memset((void *)temp, 0, sizeof(temp));
 254         memset((void *)hash, 0, sizeof(hash));
 255
 256         /* 7. Dump to seed file */
 257         /* XXX Not done here yet */
 258
 259         /* Unblock the device if it was blocked due to being unseeded */
 260         random_yarrow_unblock();
 261
 262         /* Release the reseed mutex */
 263         mtx_unlock(&random_reseed_mtx);
 264 }
 265
 266 /* Internal function to return processed entropy from the PRNG */
 267 int
 268 random_yarrow_read(void *buf, int count)
 269 {
 270         static int cur = 0;
 271         static int gate = 1;
 272         static u_char genval[KEYSIZE];
 273         size_t tomove;
 274         int i;
 275         int retval;
 276
 277         /* The reseed task must not be jumped on */
 278         mtx_lock(&random_reseed_mtx);
 279
 280         if (gate) {
 281                 generator_gate();
 282                 random_state.outputblocks = 0;
 283                 gate = 0;
 284         }
 285         if (count > 0 && (size_t)count >= sizeof(random_state.counter)) {
 286                 retval = 0;
 287                 for (i = 0; i < count; i += (int)sizeof(random_state.counter)) {
 288                         random_state.counter[0]++;
 289                         yarrow_encrypt(&random_state.key, random_state.counter,
 290                                 genval);
 291                         tomove = min(count - i, sizeof(random_state.counter));
 292                         memcpy((char *)buf + i, genval, tomove);
 293                         if (++random_state.outputblocks >=
 294                                 random_state.gengateinterval) {
 295                                 generator_gate();
 296                                 random_state.outputblocks = 0;
 297                         }
 298                         retval += (int)tomove;
 299                         cur = 0;
 300                 }
 301         }
 302         else {
 303                 if (!cur) {
 304                         random_state.counter[0]++;
 305                         yarrow_encrypt(&random_state.key, random_state.counter,
 306                                 genval);
 307                         memcpy(buf, genval, (size_t)count);
 308                         cur = (int)sizeof(random_state.counter) - count;
 309                         if (++random_state.outputblocks >=
 310                                 random_state.gengateinterval) {
 311                                 generator_gate();
 312                                 random_state.outputblocks = 0;
 313                         }
 314                         retval = count;
 315                 }
 316                 else {
 317                         retval = MIN(cur, count);
 318                         memcpy(buf,
 319                             &genval[(int)sizeof(random_state.counter) - cur],
 320                             (size_t)retval);
 321                         cur -= retval;
 322                 }
 323         }
 324         mtx_unlock(&random_reseed_mtx);
 325         return retval;
 326 }
 327
 328 static void
 329 generator_gate(void)
 330 {
 331         u_int i;
 332         u_char temp[KEYSIZE];
 333
 334         for (i = 0; i < KEYSIZE; i += sizeof(random_state.counter)) {
 335                 random_state.counter[0]++;
 336                 yarrow_encrypt(&random_state.key, random_state.counter,
 337                         &(temp[i]));
 338         }
 339
 340         yarrow_encrypt_init(&random_state.key, temp);
 341         memset((void *)temp, 0, KEYSIZE);
 342
 343 }
 344
 345 /* Helper routine to perform explicit reseeds */
 346 void
 347 random_yarrow_reseed(void)
 348 {
 349         reseed(SLOW);
 350 }