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/random_adaptors.h>
  45 #include <dev/random/randomdev_soft.h>
  46 #include <dev/random/yarrow.h>
  47
  48 RANDOM_CHECK_UINT(gengateinterval, 4, 64);
  49 RANDOM_CHECK_UINT(bins, 2, 16);
  50 RANDOM_CHECK_UINT(fastthresh, BLOCKSIZE/4, BLOCKSIZE);
  51 RANDOM_CHECK_UINT(slowthresh, BLOCKSIZE/4, BLOCKSIZE);
  52 RANDOM_CHECK_UINT(slowoverthresh, 1, 5);
  53
  54 /* Structure holding the entropy state */
  55 static struct random_state random_state;
  56
  57 static void generator_gate(void);
  58 static void reseed(u_int);
  59
  60 /* The reseed thread mutex */
  61 struct mtx random_reseed_mtx;
  62
  63 /* Process a single stochastic event off the harvest queue */
  64 void
  65 random_process_event(struct harvest *event)
  66 {
  67         u_int pl, overthreshhold[2];
  68         struct source *source;
  69         enum esource src;
  70
  71         /* Unpack the event into the appropriate source accumulator */
  72         pl = random_state.which;
  73         source = &random_state.pool[pl].source[event->source];
  74         yarrow_hash_iterate(&random_state.pool[pl].hash, event->entropy,
  75                 sizeof(event->entropy));
  76         yarrow_hash_iterate(&random_state.pool[pl].hash, &event->somecounter,
  77                 sizeof(event->somecounter));
  78         source->frac += event->frac;
  79         source->bits += event->bits + source->frac/1024;
  80         source->frac %= 1024;
  81
  82         /* Count the over-threshold sources in each pool */
  83         for (pl = 0; pl < 2; pl++) {
  84                 overthreshhold[pl] = 0;
  85                 for (src = RANDOM_START; src < ENTROPYSOURCE; src++) {
  86                         if (random_state.pool[pl].source[src].bits
  87                                 > random_state.pool[pl].thresh)
  88                                 overthreshhold[pl]++;
  89                 }
  90         }
  91
  92         /* if any fast source over threshhold, reseed */
  93         if (overthreshhold[FAST])
  94                 reseed(FAST);
  95
  96         /* if enough slow sources are over threshhold, reseed */
  97         if (overthreshhold[SLOW] >= random_state.slowoverthresh)
  98                 reseed(SLOW);
  99
 100         /* Invert the fast/slow pool selector bit */
 101         random_state.which = !random_state.which;
 102 }
 103
 104 void
 105 random_yarrow_init_alg(struct sysctl_ctx_list *clist)
 106 {
 107         int i;
 108         struct sysctl_oid *random_yarrow_o;
 109
 110         /* Yarrow parameters. Do not adjust these unless you have
 111          * have a very good clue about what they do!
 112          */
 113         random_yarrow_o = SYSCTL_ADD_NODE(clist,
 114                 SYSCTL_STATIC_CHILDREN(_kern_random),
 115                 OID_AUTO, "yarrow", CTLFLAG_RW, 0,
 116                 "Yarrow Parameters");
 117
 118         SYSCTL_ADD_PROC(clist,
 119                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 120                 "gengateinterval", CTLTYPE_INT|CTLFLAG_RW,
 121                 &random_state.gengateinterval, 10,
 122                 random_check_uint_gengateinterval, "I",
 123                 "Generation gate interval");
 124
 125         SYSCTL_ADD_PROC(clist,
 126                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 127                 "bins", CTLTYPE_INT|CTLFLAG_RW,
 128                 &random_state.bins, 10,
 129                 random_check_uint_bins, "I",
 130                 "Execution time tuner");
 131
 132         SYSCTL_ADD_PROC(clist,
 133                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 134                 "fastthresh", CTLTYPE_INT|CTLFLAG_RW,
 135                 &random_state.pool[0].thresh, (3*BLOCKSIZE)/4,
 136                 random_check_uint_fastthresh, "I",
 137                 "Fast reseed threshold");
 138
 139         SYSCTL_ADD_PROC(clist,
 140                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 141                 "slowthresh", CTLTYPE_INT|CTLFLAG_RW,
 142                 &random_state.pool[1].thresh, BLOCKSIZE,
 143                 random_check_uint_slowthresh, "I",
 144                 "Slow reseed threshold");
 145
 146         SYSCTL_ADD_PROC(clist,
 147                 SYSCTL_CHILDREN(random_yarrow_o), OID_AUTO,
 148                 "slowoverthresh", CTLTYPE_INT|CTLFLAG_RW,
 149                 &random_state.slowoverthresh, 2,
 150                 random_check_uint_slowoverthresh, "I",
 151                 "Slow over-threshold reseed");
 152
 153         random_state.gengateinterval = 10;
 154         random_state.bins = 10;
 155         random_state.pool[0].thresh = (3*BLOCKSIZE)/4;
 156         random_state.pool[1].thresh = BLOCKSIZE;
 157         random_state.slowoverthresh = 2;
 158         random_state.which = FAST;
 159
 160         /* Initialise the fast and slow entropy pools */
 161         for (i = 0; i < 2; i++)
 162                 yarrow_hash_init(&random_state.pool[i].hash);
 163
 164         /* Clear the counter */
 165         for (i = 0; i < 4; i++)
 166                 random_state.counter[i] = 0;
 167
 168         /* Set up a lock for the reseed process */
 169         mtx_init(&random_reseed_mtx, "random reseed", NULL, MTX_DEF);
 170 }
 171
 172 void
 173 random_yarrow_deinit_alg(void)
 174 {
 175         mtx_destroy(&random_reseed_mtx);
 176 }
 177
 178 static void
 179 reseed(u_int fastslow)
 180 {
 181         /* Interrupt-context stack is a limited resource; make large
 182          * structures static.
 183          */
 184         static u_char v[TIMEBIN][KEYSIZE];      /* v[i] */
 185         static struct yarrowhash context;
 186         u_char hash[KEYSIZE];                   /* h' */
 187         u_char temp[KEYSIZE];
 188         u_int i;
 189         enum esource j;
 190
 191         /* The reseed task must not be jumped on */
 192         mtx_lock(&random_reseed_mtx);
 193
 194         /* 1. Hash the accumulated entropy into v[0] */
 195
 196         yarrow_hash_init(&context);
 197         /* Feed the slow pool hash in if slow */
 198         if (fastslow == SLOW)
 199                 yarrow_hash_iterate(&context,
 200                         &random_state.pool[SLOW].hash,
 201                         sizeof(struct yarrowhash));
 202         yarrow_hash_iterate(&context,
 203                 &random_state.pool[FAST].hash, sizeof(struct yarrowhash));
 204         yarrow_hash_finish(&context, v[0]);
 205
 206         /* 2. Compute hash values for all v. _Supposed_ to be computationally
 207          *    intensive.
 208          */
 209
 210         if (random_state.bins > TIMEBIN)
 211                 random_state.bins = TIMEBIN;
 212         for (i = 1; i < random_state.bins; i++) {
 213                 yarrow_hash_init(&context);
 214                 /* v[i] #= h(v[i - 1]) */
 215                 yarrow_hash_iterate(&context, v[i - 1], KEYSIZE);
 216                 /* v[i] #= h(v[0]) */
 217                 yarrow_hash_iterate(&context, v[0], KEYSIZE);
 218                 /* v[i] #= h(i) */
 219                 yarrow_hash_iterate(&context, &i, sizeof(u_int));
 220                 /* Return the hashval */
 221                 yarrow_hash_finish(&context, v[i]);
 222         }
 223
 224         /* 3. Compute a new key; h' is the identity function here;
 225          *    it is not being ignored!
 226          */
 227
 228         yarrow_hash_init(&context);
 229         yarrow_hash_iterate(&context, &random_state.key, KEYSIZE);
 230         for (i = 1; i < random_state.bins; i++)
 231                 yarrow_hash_iterate(&context, &v[i], KEYSIZE);
 232         yarrow_hash_finish(&context, temp);
 233         yarrow_encrypt_init(&random_state.key, temp);
 234
 235         /* 4. Recompute the counter */
 236
 237         for (i = 0; i < 4; i++)
 238                 random_state.counter[i] = 0;
 239         yarrow_encrypt(&random_state.key, random_state.counter, temp);
 240         memcpy(random_state.counter, temp, sizeof(random_state.counter));
 241
 242         /* 5. Reset entropy estimate accumulators to zero */
 243
 244         for (i = 0; i <= fastslow; i++) {
 245                 for (j = RANDOM_START; j < ENTROPYSOURCE; j++) {
 246                         random_state.pool[i].source[j].bits = 0;
 247                         random_state.pool[i].source[j].frac = 0;
 248                 }
 249         }
 250
 251         /* 6. Wipe memory of intermediate values */
 252
 253         memset((void *)v, 0, sizeof(v));
 254         memset((void *)temp, 0, sizeof(temp));
 255         memset((void *)hash, 0, sizeof(hash));
 256
 257         /* 7. Dump to seed file */
 258         /* XXX Not done here yet */
 259
 260         /* Unblock the device if it was blocked due to being unseeded */
 261         random_yarrow_unblock();
 262
 263         /* Release the reseed mutex */
 264         mtx_unlock(&random_reseed_mtx);
 265 }
 266
 267 /* Internal function to return processed entropy from the PRNG */
 268 int
 269 random_yarrow_read(void *buf, int count)
 270 {
 271         static int cur = 0;
 272         static int gate = 1;
 273         static u_char genval[KEYSIZE];
 274         size_t tomove;
 275         int i;
 276         int retval;
 277
 278         /* The reseed task must not be jumped on */
 279         mtx_lock(&random_reseed_mtx);
 280
 281         if (gate) {
 282                 generator_gate();
 283                 random_state.outputblocks = 0;
 284                 gate = 0;
 285         }
 286         if (count > 0 && (size_t)count >= sizeof(random_state.counter)) {
 287                 retval = 0;
 288                 for (i = 0; i < count; i += (int)sizeof(random_state.counter)) {
 289                         random_state.counter[0]++;
 290                         yarrow_encrypt(&random_state.key, random_state.counter,
 291                                 genval);
 292                         tomove = min(count - i, sizeof(random_state.counter));
 293                         memcpy((char *)buf + i, genval, tomove);
 294                         if (++random_state.outputblocks >=
 295                                 random_state.gengateinterval) {
 296                                 generator_gate();
 297                                 random_state.outputblocks = 0;
 298                         }
 299                         retval += (int)tomove;
 300                         cur = 0;
 301                 }
 302         }
 303         else {
 304                 if (!cur) {
 305                         random_state.counter[0]++;
 306                         yarrow_encrypt(&random_state.key, random_state.counter,
 307                                 genval);
 308                         memcpy(buf, genval, (size_t)count);
 309                         cur = (int)sizeof(random_state.counter) - count;
 310                         if (++random_state.outputblocks >=
 311                                 random_state.gengateinterval) {
 312                                 generator_gate();
 313                                 random_state.outputblocks = 0;
 314                         }
 315                         retval = count;
 316                 }
 317                 else {
 318                         retval = MIN(cur, count);
 319                         memcpy(buf,
 320                             &genval[(int)sizeof(random_state.counter) - cur],
 321                             (size_t)retval);
 322                         cur -= retval;
 323                 }
 324         }
 325         mtx_unlock(&random_reseed_mtx);
 326         return retval;
 327 }
 328
 329 static void
 330 generator_gate(void)
 331 {
 332         u_int i;
 333         u_char temp[KEYSIZE];
 334
 335         for (i = 0; i < KEYSIZE; i += sizeof(random_state.counter)) {
 336                 random_state.counter[0]++;
 337                 yarrow_encrypt(&random_state.key, random_state.counter,
 338                         &(temp[i]));
 339         }
 340
 341         yarrow_encrypt_init(&random_state.key, temp);
 342         memset((void *)temp, 0, KEYSIZE);
 343
 344 }
 345
 346 /* Helper routine to perform explicit reseeds */
 347 void
 348 random_yarrow_reseed(void)
 349 {
 350         reseed(SLOW);
 351 }